https://wiki.richmondmakerlabs.uk/api.php?action=feedcontributions&user=IanM&feedformat=atomrichmondmakerlabs.uk - User contributions [en]2024-03-29T15:40:30ZUser contributionsMediaWiki 1.41.0https://wiki.richmondmakerlabs.uk/index.php?title=Talk:Ian_M%27s_Lathe_Notes&diff=17691Talk:Ian M's Lathe Notes2024-03-27T00:45:48Z<p>IanM: /* Speed control */</p>
<hr />
<div>[[User:IanM|IanM]] ([[User talk:IanM|talk]]) 07:59, 1 June 2023 (UTC) Comments, corrections and feedback from other RML lathe users and/or experienced machinists are welcome.<br />
<br />
== Speed control ==<br />
<br />
The negative side of the SCR controlled bridge uses MUR1660 dual common cathode diodes, which are currently blown due to swarf ingress. No other damage occurred.<br />
Need 2+ new diodes, fresh TO220 sil-pads and some 1 1.4" 8A fuses.<br />
<br />
https://services.ts.com.tw/storage/resources/datasheet/MUR1620CT%20SERIES_I2104.pdf<br />
<br />
== Notes for spindle roller bearing upgrade ==<br />
<br />
* http://mikesworkshop.weebly.com/headstock-upgrade.html - blog of this upgrade on a very similar lathe<br />
* https://youtu.be/HYOgmhpBUJs - Video of upgrade on minilathe without Hi/Lo gear with discussion of setting the taper roller preload<br />
* https://www.arceurotrade.co.uk/projects/C3_BC/C3-bearing-change.html - Step by step guide on a Sieg C3<br />
* https://groups.io/g/7x12MiniLathe/topic/mini_lathe_spindle_tapered/82278520 - discussion of lubrication issues post-upgrade<br />
* https://www.mini-lathe.com/Mini_lathe/Tuning/headstock/headstock.htm - disassembly *without* a puller. Note the use of a rawhide mallet. Our spindle is already marred by someone beating on it with a hammer :(<br />
<br />
''When we get around to this, it would be worth replacing the two rear socket headed cap screws holding the headstock to the bed with hex headed machine screws, so future headstock maintenance can be performed without removing the motor.''<br />
<br />
[[User:IanM|IanM]] ([[User talk:IanM|talk]]) 09:10, 17 October 2023 (UTC)<br />
<br />
== Concept for a boring bar holder ==<br />
<br />
We need the capability to use small boring bars <10mm shank. The main problem at small sizes is rigidity, so it is probably desirable to avoid the QC toolholder. The 4 way toolpost can clamp 16mm but the slot base is 10.4 mm below center height, leaving only 5.6mm above, not enough for a 10mm toolholder.<br />
<br />
Raising the whole toolpost 2.5mm (ideally 2.4mm) would be a game-changer, giving 7.9mm below and 8.1mm above center height allowing a block clamped directly in the toolpost to be bored for up to 1/2" (12.5mm) shank tooling. After boring, slit one side of the block for clamping, so it flexes when the toolpost clamping screws are tightened, clamping the round tool shank. Littlemachineshop.com (USA) sell a 1/2" boring bar holder of this style but it would be uneconomic to import. <br />
<br />
To bore it, first drill slightly under diameter with the drill bit in the 3 jaw chuck, then use the 4 jaw chuck to hold a boring bar with the desired offset.<br />
<br />
2.5mm Aluminium sheet is probably the best choice to raise the toolpost - cut 50mm square ?? and drilled for the center stud. The boring bar holder is probably best made of 16mm aluminium square bar.<br />
<br />
Update: Bought a set of 9 3/8" shank boring bars.<br />
The shanks are 9.45mm and tip heights are around 2.4mm above center with some outliers +/- 0.2 mm. Therefore after boring the holder block 9.5mm (test drill an ally offcut 9.5mm and see how close to shank size it is, but I bet it will need boring), with the 2.5mm shim under the toolpost, remove the shim, and touch up the tips to correct relief and rake with the bar rotate to bring the point to a thou or so above center. Worst case I may need to file the top of the holder block to allow it to be shimmed up a few thou.<br />
<br />
[[User:IanM|IanM]] ([[User talk:IanM|talk]]) 16:11, 29 July 2023 (UTC)<br />
<br />
== Lathe dog and drive pin ==<br />
<br />
Needed for turning between centers. See https://littlemachineshop.com/products/product_view.php?ProductID=4464 for the general style I propose.<br />
<br />
Scaling from the photos, the M8 drive pin is 60mm long, threaded for half its length. The quick & dirty option here is cut down a M8 x70mm or x80mm hex headed bolt and round its end.<br />
<br />
The smallest (10mm capacity) dog has a 41.5 mm x 7 mm tail, and a M5 screw.<br />
The 20mm capacity dog has a 32.5 mm x 11 mm tail and a M8 screw.<br />
30mm is similar but with a 35mm tail.<br />
I have an offcut of 25mm bore heavy pipe, that should be suitable for stock in the range 15mm to 25mm.<br />
<br />
A Counterbalance weight is commonly fitted to the spindle nose hole opposite the drive pin. <br />
ToDo: calculate balance weight<br />
<br />
[[User:IanM|IanM]] ([[User talk:IanM|talk]]) 03:59, 31 July 2023 (UTC)<br />
<br />
== Fine Feed ==<br />
A 3D printed set of cojoined 80/15 tooth (for the BC shaft) and 90 tooth gears can increase the reduction ration from the standard 16:1 to 24:1 giving a 0.0625 mm fine feed. Although they can be bought from LittleMachineShop: https://littlemachineshop.com/products/product_view.php?ProductID=1137 I think we can print them ourselves in ABS and am working on OpenSCAD models for them. The C-D reduction can possibly be improved with a 14T pinion driving a 91T gear on D, which gives 26:1 and 0.0577 mm feed.<br />
[[User:IanM|IanM]] ([[User talk:IanM|talk]]) 12:19, 17 October 2023 (UTC)<br />
<br />
== Other desirable mods ==<br />
* https://gadgetbuilder.com/ThreadingTools.html#AutoStop - Auto-disengage for the half-nuts.<br />
<br />
: Can we do this better? Possibly a V groove in an actuator pin through a block to lift a ball bearing in a cross hole in the block to push a strong spring round the half-nut lever base off a catch pin. Engaging the half-nuts cocks the spring, which is then held with no force on the lever till it trips.<br />
<br />
: N.B. GadgetBuilder had a crash due to the half-nuts failing to disengage under load. It may need a backup electrical trip via a heavy duty relay to interrupt power to the ZVR stop/start switch, or maybe retrofit a 5 pin ZVR switch so the electrical trip only has to interrupt the coil current. It may also be possible to use the motor controller's low current inhibit circuit, though for safety, it would need to latch till the speed knob inhibit switch closes or power is cycled.<br />
<br />
: On further consideration, an electromechanical trip may be preferable to the mechanical one, triggering a 'brute force' solenoid to disengage the half nuts, as continued over-travel if the trip fails could then stop the motor. [[User:IanM|IanM]] ([[User talk:IanM|talk]]) 12:09, 17 October 2023 (UTC)<br />
<br />
* https://www.youtube.com/watch?v=_PuSl_PyMNI - Copper soft jaws from water pipe<br />
: Set for the 3 jaw chuck completed 10/10/2023.<br />
: ToDo: Make a set for the 4 jaw chuck.<br />
<br />
== Spares/Accessories for consideration ==<br />
Arceurotrade<br />
https://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C2-Mini-Lathe-Spares/C2-180A-Potentiometer-with-Switch - Right value and switch type, but has splined 6mm shaft. £10.64<br />
https://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C3-Mini-Lathe-Spares/C3-256-Leadscrew-Grommet-Dustproof-Cover - Leadscrew shaped grommet to exclude swarf, £3.35<br />
<br />
The drive belt is a modulus timing belt, '''1.5x70''' That's 1.5*PI (~4.712 mm) pitch, 70 tooth, so approx 329.8 mm long. According to Amadeal its nom. 9.8 mm wide, but the motor pully endcap has been shimmed to allow a slightly wider belt and a standard 10 mm one will fit.<br />
<br />
== Old: Grinding spindle nose to fix 3 jaw chuck seating ==<br />
I made a proposal to resolve the chuck seating issue (Telegram message to Ian B):<blockquote><i>On further thinking about the misfitting three jaw chuck, neither the four jaw chuck nor the faceplate require that precise alignment, as one always adjusts the work held by/on them to run true, so a tiny increase in their runout when mounted will be insignificant.<br><br>As a replacement spindle is only £52 but a replacement 4" three jaw chuck is £120, the lowest risk cure for our excessively tight fitting chuck would be to turn down the register (outer) diameter of the lip (inner ring) of the spindle nose till the three jaw chuck just fits cleanly.<br><br>As there's very little to be taken off, setting up a Dremel in a 3D printed adapter for toolpost grinding is probably the best approach.</i></blockquote><i>Ian B concurred:</i><blockquote><i>I'm in full agreement with your suggestion, to grind the lip of the spindle.<br><br>Changing chucks should be easily done and having to whack the three jaw chuck to remove it can't be good for a lightweight lathe like ours.<br><br>And you're saying the grinding bit of a Dremel will be adequate for the spindle? Perfect.</i></blockquote><br />
TLDR: We have fixed it!</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Talk:Ian_M%27s_Lathe_Notes&diff=17690Talk:Ian M's Lathe Notes2024-03-27T00:45:04Z<p>IanM: /* Notes for spindle roller bearing upgrade */</p>
<hr />
<div>[[User:IanM|IanM]] ([[User talk:IanM|talk]]) 07:59, 1 June 2023 (UTC) Comments, corrections and feedback from other RML lathe users and/or experienced machinists are welcome.<br />
<br />
== Speed control ==<br />
<br />
The negative side of the SCR controlled bridge uses MUR1660 dual common cathode diodes, which are currently blown due to swarf ingress. No other damage occurred.<br />
Need 2+ new diodes + fresh TO220 sil-pads.<br />
<br />
https://services.ts.com.tw/storage/resources/datasheet/MUR1620CT%20SERIES_I2104.pdf<br />
<br />
== Notes for spindle roller bearing upgrade ==<br />
<br />
* http://mikesworkshop.weebly.com/headstock-upgrade.html - blog of this upgrade on a very similar lathe<br />
* https://youtu.be/HYOgmhpBUJs - Video of upgrade on minilathe without Hi/Lo gear with discussion of setting the taper roller preload<br />
* https://www.arceurotrade.co.uk/projects/C3_BC/C3-bearing-change.html - Step by step guide on a Sieg C3<br />
* https://groups.io/g/7x12MiniLathe/topic/mini_lathe_spindle_tapered/82278520 - discussion of lubrication issues post-upgrade<br />
* https://www.mini-lathe.com/Mini_lathe/Tuning/headstock/headstock.htm - disassembly *without* a puller. Note the use of a rawhide mallet. Our spindle is already marred by someone beating on it with a hammer :(<br />
<br />
''When we get around to this, it would be worth replacing the two rear socket headed cap screws holding the headstock to the bed with hex headed machine screws, so future headstock maintenance can be performed without removing the motor.''<br />
<br />
[[User:IanM|IanM]] ([[User talk:IanM|talk]]) 09:10, 17 October 2023 (UTC)<br />
<br />
== Concept for a boring bar holder ==<br />
<br />
We need the capability to use small boring bars <10mm shank. The main problem at small sizes is rigidity, so it is probably desirable to avoid the QC toolholder. The 4 way toolpost can clamp 16mm but the slot base is 10.4 mm below center height, leaving only 5.6mm above, not enough for a 10mm toolholder.<br />
<br />
Raising the whole toolpost 2.5mm (ideally 2.4mm) would be a game-changer, giving 7.9mm below and 8.1mm above center height allowing a block clamped directly in the toolpost to be bored for up to 1/2" (12.5mm) shank tooling. After boring, slit one side of the block for clamping, so it flexes when the toolpost clamping screws are tightened, clamping the round tool shank. Littlemachineshop.com (USA) sell a 1/2" boring bar holder of this style but it would be uneconomic to import. <br />
<br />
To bore it, first drill slightly under diameter with the drill bit in the 3 jaw chuck, then use the 4 jaw chuck to hold a boring bar with the desired offset.<br />
<br />
2.5mm Aluminium sheet is probably the best choice to raise the toolpost - cut 50mm square ?? and drilled for the center stud. The boring bar holder is probably best made of 16mm aluminium square bar.<br />
<br />
Update: Bought a set of 9 3/8" shank boring bars.<br />
The shanks are 9.45mm and tip heights are around 2.4mm above center with some outliers +/- 0.2 mm. Therefore after boring the holder block 9.5mm (test drill an ally offcut 9.5mm and see how close to shank size it is, but I bet it will need boring), with the 2.5mm shim under the toolpost, remove the shim, and touch up the tips to correct relief and rake with the bar rotate to bring the point to a thou or so above center. Worst case I may need to file the top of the holder block to allow it to be shimmed up a few thou.<br />
<br />
[[User:IanM|IanM]] ([[User talk:IanM|talk]]) 16:11, 29 July 2023 (UTC)<br />
<br />
== Lathe dog and drive pin ==<br />
<br />
Needed for turning between centers. See https://littlemachineshop.com/products/product_view.php?ProductID=4464 for the general style I propose.<br />
<br />
Scaling from the photos, the M8 drive pin is 60mm long, threaded for half its length. The quick & dirty option here is cut down a M8 x70mm or x80mm hex headed bolt and round its end.<br />
<br />
The smallest (10mm capacity) dog has a 41.5 mm x 7 mm tail, and a M5 screw.<br />
The 20mm capacity dog has a 32.5 mm x 11 mm tail and a M8 screw.<br />
30mm is similar but with a 35mm tail.<br />
I have an offcut of 25mm bore heavy pipe, that should be suitable for stock in the range 15mm to 25mm.<br />
<br />
A Counterbalance weight is commonly fitted to the spindle nose hole opposite the drive pin. <br />
ToDo: calculate balance weight<br />
<br />
[[User:IanM|IanM]] ([[User talk:IanM|talk]]) 03:59, 31 July 2023 (UTC)<br />
<br />
== Fine Feed ==<br />
A 3D printed set of cojoined 80/15 tooth (for the BC shaft) and 90 tooth gears can increase the reduction ration from the standard 16:1 to 24:1 giving a 0.0625 mm fine feed. Although they can be bought from LittleMachineShop: https://littlemachineshop.com/products/product_view.php?ProductID=1137 I think we can print them ourselves in ABS and am working on OpenSCAD models for them. The C-D reduction can possibly be improved with a 14T pinion driving a 91T gear on D, which gives 26:1 and 0.0577 mm feed.<br />
[[User:IanM|IanM]] ([[User talk:IanM|talk]]) 12:19, 17 October 2023 (UTC)<br />
<br />
== Other desirable mods ==<br />
* https://gadgetbuilder.com/ThreadingTools.html#AutoStop - Auto-disengage for the half-nuts.<br />
<br />
: Can we do this better? Possibly a V groove in an actuator pin through a block to lift a ball bearing in a cross hole in the block to push a strong spring round the half-nut lever base off a catch pin. Engaging the half-nuts cocks the spring, which is then held with no force on the lever till it trips.<br />
<br />
: N.B. GadgetBuilder had a crash due to the half-nuts failing to disengage under load. It may need a backup electrical trip via a heavy duty relay to interrupt power to the ZVR stop/start switch, or maybe retrofit a 5 pin ZVR switch so the electrical trip only has to interrupt the coil current. It may also be possible to use the motor controller's low current inhibit circuit, though for safety, it would need to latch till the speed knob inhibit switch closes or power is cycled.<br />
<br />
: On further consideration, an electromechanical trip may be preferable to the mechanical one, triggering a 'brute force' solenoid to disengage the half nuts, as continued over-travel if the trip fails could then stop the motor. [[User:IanM|IanM]] ([[User talk:IanM|talk]]) 12:09, 17 October 2023 (UTC)<br />
<br />
* https://www.youtube.com/watch?v=_PuSl_PyMNI - Copper soft jaws from water pipe<br />
: Set for the 3 jaw chuck completed 10/10/2023.<br />
: ToDo: Make a set for the 4 jaw chuck.<br />
<br />
== Spares/Accessories for consideration ==<br />
Arceurotrade<br />
https://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C2-Mini-Lathe-Spares/C2-180A-Potentiometer-with-Switch - Right value and switch type, but has splined 6mm shaft. £10.64<br />
https://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C3-Mini-Lathe-Spares/C3-256-Leadscrew-Grommet-Dustproof-Cover - Leadscrew shaped grommet to exclude swarf, £3.35<br />
<br />
The drive belt is a modulus timing belt, '''1.5x70''' That's 1.5*PI (~4.712 mm) pitch, 70 tooth, so approx 329.8 mm long. According to Amadeal its nom. 9.8 mm wide, but the motor pully endcap has been shimmed to allow a slightly wider belt and a standard 10 mm one will fit.<br />
<br />
== Old: Grinding spindle nose to fix 3 jaw chuck seating ==<br />
I made a proposal to resolve the chuck seating issue (Telegram message to Ian B):<blockquote><i>On further thinking about the misfitting three jaw chuck, neither the four jaw chuck nor the faceplate require that precise alignment, as one always adjusts the work held by/on them to run true, so a tiny increase in their runout when mounted will be insignificant.<br><br>As a replacement spindle is only £52 but a replacement 4" three jaw chuck is £120, the lowest risk cure for our excessively tight fitting chuck would be to turn down the register (outer) diameter of the lip (inner ring) of the spindle nose till the three jaw chuck just fits cleanly.<br><br>As there's very little to be taken off, setting up a Dremel in a 3D printed adapter for toolpost grinding is probably the best approach.</i></blockquote><i>Ian B concurred:</i><blockquote><i>I'm in full agreement with your suggestion, to grind the lip of the spindle.<br><br>Changing chucks should be easily done and having to whack the three jaw chuck to remove it can't be good for a lightweight lathe like ours.<br><br>And you're saying the grinding bit of a Dremel will be adequate for the spindle? Perfect.</i></blockquote><br />
TLDR: We have fixed it!</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Facilities&diff=17689Facilities2024-03-27T00:39:28Z<p>IanM: /* Lathe */</p>
<hr />
<div><!--<br />
New facilites page by Andy (beardedfool)<br />
Problem:<br />
I found RML through the wiki (only discovering the www page after I had visited) and couldn't find what I was looking for easily - what toys you had there. <br />
<br />
e.g. There's an inventory page and a facilities page which seem to duplicate information - but neither link to useful other pages e.g. the laser cutter page.<br />
<br />
Solution<br />
I've had a go at clearing them up. I'd like to 'give back' by creating some instructions for equipment as people are kind enough to show me them (e.g. lathe, laser cutter, CNC, 3D printing)<br />
Tidying these pages is the first step - then I can use this page as a jump off for these instructions.<br />
<br />
As it's a bit presumptious - I've largely kept the content the same at the moment, apart from minor edits for clarity. I suspect it's still not wholly accurate in terms of assets you have, other pages that should be linked or out of date content but hopefully a start<br />
<br />
Testing<br />
As I don't have editing rights to the wiki I put it into https://www.mediawiki.org/wiki/Project:Sandbox by edit source' button and looks largely right but problems with images likely - kept most the <br clear=all> tags in but may be a better way https://en.wikipedia.org/wiki/Template_talk:Clear <br />
<br />
Questions/ next steps<br />
Create repository on your github for this? May be an unwanted layer of abstraction, but as it's code. <br />
<br />
Contact people about Asset database (Dan), Laser Cutter materials (Kim) and other 3D printers (Paul B)<br />
<br />
Add to wiki LHS navigation menu as Facilities; redirect inventory page to this - #REDIRECT [[Facilities]]<br />
<br />
Create other instructions over time<br />
<br />
<br />
Code starts... --><br />
<br />
=Audio Visual=<br />
===Bluetooth-enabled Stereo===<br />
How to use<br />
# Turn on the power switch connected to the stereo to the right of the double-doors. <br />
# Press "VIDEO/AUX" on the stereo input dial (in the middle) to connect it to the Bluetooth receiver. <br />
# On your Bluetooth-enabled smartphone or laptop device, go into your Bluetooth preferences and search for devices. You will see "Belkin HD" as one of the available devices. Pair it with your device and start playing music/podcasts/Internet streams. <br />
# If you do not see "Belkin HD" then power cycle the Belkin device and search again.<br />
<!--<br />
===Plasma screen===<br />
[[File: PlasmaScreen.jpg |200px|right | Plasma Screen]]<br />
Huge screen. Can't miss it. HDMI, DVI, ... sound is the only thing that does not work. <br />
More information [[Panasonic_TH-65PF12EK|here]]<br />
--><br />
<br clear=all><br />
<br />
=CAD - Computer aided design=<br />
===Laser cutter===<br />
[[File: LaserCutter.jpg |200px|right | Laser Cutter]]<br />
<br />
Privately owned Laser cutter (60W) can be used periodically for prototyping. <br />
<br />
[[Laser_cutter|Has it's own page here]]<br />
<br />
''Please do not use the laser cutter until you have received induction''<br />
===3D printing===<br />
We have several 3D printers that can be used to print downloaded models or rapidly prototype your designs.<br />
<br />
Some basics on 3D printing [[3dprinting-basics|here]]<br />
<br />
Our Printers:<br />
<br />
====Flashforge adventurer 3====<br />
[https://www.flashforge.com/product-detail/flashforge-adventurer-3-3d-printer Flashforge's page ]<br />
<br />
====Geeetech I3 pro B====<br />
[[Geetech_I3_Pro_B| here]]<br />
<br />
====Zombie Printer====<br />
A machine so modified it got a new name<br />
* Dedicated page [[The_Zombie_Printer|here]]<br />
<br />
[[File: 3DPrinter.jpg |200px|right | 3D printer]]<br />
<br />
<!--<br />
NB this is all commented out but I want to keep the text as we still have some of the machines<br />
<br />
====BIQU Magician====<br />
* A good machine as an introduction to 3D printers for new-comers. Works well with minimal changes of settings. More here<br />
====[http://www.deltamaker.com/ DeltaMaker] 3D printer====<br />
it is connected to the network via [https://octoprint.org/ octoprint]. <br />
* When you are at little house point your web browser to http://deltamaker.rml<br />
* Login to octoprint with <br />
**user:rml <br />
**password: rml<br />
* ssh <br />
** pi<br />
** deltamaker<br />
<br />
====Geetech Dual Extruder====<br />
Currently only one extruder working<br />
* GT2560 board<br />
====Formlabs 1+ resin printer====<br />
[[https://wiki.richmondmakerlabs.uk/index.php/Formlabs_3d_printer here]]<br />
====Phrozen resin printer====<br />
Web GUI, IP is shown when machine is started. Has a slicer built in<br />
--><br />
<br />
===CNC Machines===<br />
====CNC Mill====<br />
N.B. This is currently not operational<br />
<br />
[[File: CNCRouter.jpg |200px|right | CNC machine]]<br />
CNC Mill - OpenBuilds [https://openbuilds.com/builds/c-beam%C2%AE-machine-plate-maker.2020/ C-Beam CNC Router] <br />
In the cloakroom<br />
<br />
''Please do not use the CNC Mill until you have received induction''<br />
* Instructions on use from Leo [[CncMill|here]] and Nick [https://web.archive.org/web/20210928032955/https://ndevenish.com/2017/01/26/cnc-update.html here (Internet Archive)]<br />
<br clear=all><br />
<br />
====CNC Metal Mill====<br />
N.B. This is not yet operational<br />
<br />
Denford MicroMill<br />
<br />
====CNC Lathe====<br />
Denford MicroMill<br />
N.B. This is not yet operational<br />
<br />
Denford Microturn<br />
<br />
=Crafts=<br />
===Sewing machine===<br />
There is a mini sewing machine from John Lewis on loan from Andres. Feel free to use when ever. It is kept in its box on the gray shelves next to the kitchen. <br />
Follow this video for [https://www.youtube.com/watch?v=eFABAbK4Beo threading] and first steps! <br clear=all><br />
<br />
=Electronics workbench=<br />
[[File:Electronics Bench 2022.jpeg |200px|right |Electronics Bench]]<br />
[[File:20221206 Electronics.jpg|200px|right |Electronics Bench in use]]<br />
See our [[Electronics]] page for notes, tutorial links, etc.<br />
===General===<br />
* Various hand tools, test equipment, wiring, connectors, resistors, capacitors, LEDs and other assorted components<br />
* UV exposure box<br />
* Magnifying lamp<br />
* 'Helping Hands'<br />
** Two positionable clips to hold wires, components and small assemblies<br />
** Magnifier<br />
* Tiltable plastic jawed vice<br />
** for holding small to medium PCBs and small assemblies<br />
** ''Do *NOT* use for assembling IDC cables or forcing a fit - grab a drill press vice from the engineering bench for that!''<br />
<br />
===Soldering/Desoldering===<br />
* Weller WS80 temperature controlled soldering station<br />
** with WSP80 iron (24V, 80W)<br />
** takes [https://docs.rs-online.com/9b2b/0900766b803f878a.pdf LT series tips]<br />
** [https://www.pkelektronik.com/media/downloads/w/e/weller%20loetstation%20ws%2080.pdf Operating Instructions] - Controls/Connections layout on pages 2 & 3, English instructions start at page 23<br />
* <s>Maplin (Precision Gold) temperature controlled soldering station</s> - ''U/S as of 5/10/2022''<br />
** with 24V, 48W iron - ''element failed''<br />
** Chinese OEM: [http://www.china-zhongdi.com/?keyword=ZD-937 Zongdi ZD-937] <br />
** UK source for spares: [https://uk.farnell.com/duratool/d00675/soldering-station-48w-230v-uk/dp/1498364 Duratool D00675 @Farnell]<br />
* Power+ 8000 series SMD Rework Station<br />
** A 'knockoff' of a [http://yihua-soldering.com/product-1-1-1-2in1-hot-air-rework-station-en/147633/ Yihua 852D+] - [https://www.manualslib.com/manual/2488638/Yihua-706-Series.html#product-852%20Series 852D+ Manual]<br />
** Variable temperature and flow hot air tool - ''Missing its hot air nozzles apart from the 6 mm one fitted.''<br />
** 50W temperature controlled soldering iron - Takes HAKKO 900 series tips. <br />
*** The iron is a Yihua 907A clone, five pin GX16 connector, male on the station, female on the iron, [[:File:Yihua GX16.png|Yihua pinout]]. The iron has an A1322 clone element nom. 24V 50W. Tips should be 6 - 6.5 mm OD, and nom. 4 mm ID.<br />
<br />
:: ''N.B. Tips must be a good close fit on the ceramic element, but not excessively tight. Many clone tips are too loose and will need a sleeve to function. If the tip is too tight there is a high risk of breaking the element.'' <br />
<br />
:: ''Yihua knockoffs are not known for their electrical safety. A test sticker indicates it passed in 2018 (probably PAT testing) and the hot air nozzle is grounded, but we should check if there is a reliable ground at the soldering iron socket. See [https://www.eevblog.com/forum/reviews/w-e-p-yihua-852d-combined-hot-air-station-and-soldering-iron/ 852D topic @EEVblog]''<br />
<br />
* BGA re-balling station - [https://www.youtube.com/watch?v=fNxXn32L74o YouTube demo]<br />
** Uses same Yihua 907A type iron as the SMD rework station. <br />
* Solder sucker station - see: [http://www.ameritronics.com/digital_desolddering_de-soldering_stations_tools.htm HOW TO DESOLDER THROUGH HOLE COMPONENTS, CONNECTORS & CHIPS?]<br />
<br />
===Bench Power Supply===<br />
* Thurlby PL320 Bench Power Supply<br />
** dual channel 0-30V, 2A<br />
**[http://www.av.it.pt/medidas/Data/Manuais%20&%20Tutoriais/05%20-%20Programable%20Power%20Supplay%20PL330DP/PL%20Series%20Instruction%20Manual%20-%20Iss%2012.pdf PL series instruction Manual]<br />
<br />
===Pulse Generator===<br />
* AIM & THURLBY THANDAR INSTRUMENTS TGP110 10Mhz Pulse Generator<br />
** [http://www.farnell.com/datasheets/1734341.pdf?_ga=2.28719740.1736682119.1560968692-1735494415.1560968692 datasheet]<br />
<br />
===Oscilloscope===<br />
*Rigol DS1104Z<br />
**4 channel 50MHz Digital Oscilloscope<br />
**[https://www.batronix.com/pdf/Rigol/UserGuide/DS1000Z_UserGuide_EN.pdf Manual]<br />
<br />
===Multimeters===<br />
* [https://dam-assets.fluke.com/s3fs-public/75_77___omeng0900.pdf Fluke 77] DMM (grey, in brown rubber bumper)<br />
** ''N.B. Rotary mode switch detent is very weak, so carefully align pointer with desired mode indication before use.''<br />
* [https://dam-assets.fluke.com/s3fs-public/7x2x____iseng0200.pdf Fluke 77 III] DMM (grey/yellow)<br />
* Various cheap small DMMs - See Big Clive's [https://youtu.be/-QDW0LRQVrY video review/tutorial] <br />
** ''CAUTION: Do *NOT* use the cheap DMMs on live mains circuits''<br />
<br />
''Please carefully check the red test lead is *NOT* plugged in the 300mA or 10A (current) sockets before making voltage measurements, as the Fluke current range fuses are expensive to replace!''<br />
<br />
=== PC/Mac hosted tools ===<br />
* [https://en.wikipedia.org/wiki/LTspice LTspice XVII] circuit simulator is installed on the all-in-one Mac next to the electronics bench. ''<s>(PC version running under WineBottler)</s>''<br />
* Arduino IDE (v1.8.19) is installed on the same Mac.<br />
* An eight channel USB logic analyser ''(Salae Logic 8 clone)'' is available ''(bin on the electronics shelves at the end over the wood store)'', and the [https://sigrok.org/wiki/Main_Page Sigrok] software to support it is installed on the Mac.<br />
<br />
=Makers Equipment=<br />
* Arduino Starter kit<br />
* Funduino kit with loads of sensors<br />
* Raspberry Pi (with Pi Camera)<br />
<br clear=all><br />
<br />
=Engineering/ Woodwork=<br />
<br />
===Bench drill press===<br />
*Silverline 262212 Drill press<br />
**Chuck Capacity 13mm<br />
** 350W<br />
See our [[Drill press]] page for general instructions and its [https://www.silverlinetools.com/en-GB/Product/ProductDetail?ModelName=262212 Manual] for specifics.<br />
<br />
<br clear=all><br />
<br />
===Lathe===<br />
[[File: Lathe2.jpg |200px|right | Lathe]]<br />
In the kitchen. Unfortunately, currently out of order. <br />
<br />
Marked as a CJ18A Mini-Lathe from [[https://www.amadeal.co.uk/acatalog/CJ18A-Mini-Lathe-7x14-Machine-100mm-3jaw-Metric-With-Metal-Gears-AMA_LA_CJ18_M_3_MGRB.html Amadeal]]<br />
[[https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Manual]]<br />
<br />
[[Media:Lathe InductionNotes.pdf| Induction Document]]<br />
<br />
Possible upgrades:<br />
*https://www.youtube.com/watch?v=GwT-JQLbNPA<br />
<br />
''Please do not use the lathe until you have received induction'' <br />
<br />
[[User:IanM|IanM]] has written some more detailed [[Ian M's Lathe Notes|notes on using the RML Lathe]].<br />
<br />
===Bandsaw===<br />
N B This is out of action and in need of replacement<br />
<br />
*Nutool HBS230 230mm Two Wheel Bandsaw <br />
**230W <br />
**Similar [https://www.workshopping.co.uk/files/09681ins.pdf Manual]<br />
*Replacement parts:<br />
**Got some tyres from [www.Solenttools.co.uk solent tools]<br />
**Ian got a new blade from ???<br />
<br />
===Jigsaw===<br />
Bosch PST 700E 500W Jigsaw<br />
[https://www.bosch-diy.com/gb/en/p/pst-700-e-06033a0000-v100024162 Manual]<br />
<br />
===Mitresaw===<br />
Erbauer ERB255GS 2000W 10" Sliding compound mitre saw with laser<br />
<br />
===Router (handheld)===<br />
Black & Decker KW850E 1100W </br><br />
[http://2helpu.com/PDMSDocuments/EU/Docs//docpdf/kw850e_uk.pdf here Manual]<br />
<br />
===Planer (handheld)===<br />
Ryobi EPN-6082 600W </br><br />
[http://www.free-instruction-manuals.com/pdf/p41861.pdf Manual]</br><br />
<br />
===Bench Grinder===<br />
Clarke Metalworker CBG 6RZ </br><br />
[https://www.clarkeservice.co.uk/product_manuals/metalworking_bench_grinders.shtml Manual]<br />
<br />
===Belt Sander===<br />
N.B. We no longer have this as the motor broke. Kept as a reminder we need one and for safety warning<br />
*KOBE KBE2714140K<br />
*[https://www.manualslib.com/manual/1229237/Kobe-Sbd370.html Manual] and [https://cromindo.com/uploads/product_info/KBE/271/KBE2714140K_5.pdf here]<br />
**Safety: Please don't use the dust extraction when sanding metal - hot sparks, wood chippings and lots of air equals fire<br />
<br />
===Compressor===<br />
[[File: Compressor.jpg |200px|right | Compressor]]<br />
Mains-powered air compressor with a long air pipe and a few tools, including paint sprayer. <br />
<br clear=all><br />
* Ratchet tap handles<br />
* 0 - 10 BA tap & die set (imperial)<br />
* Broken bolt extractor set (Easy Outs)<br />
<br clear=all><br />
<br />
=General purpose=<br />
* Ultrasonic cleaner (6.5L) - Tank internal dimension: 300 (L) x 150 (D) x 150 (H) mm<br />
* Small screw driver set with prying tool for mobile phone disassembly<br />
* Spanner set 6mm to 26mm - ''In cloakroom, on bathroom door''<br />
* Hot glue gun<br />
* Dremel 200 rotary Multi-Tool (two speed - 15K/35K RPM no load) - [https://www.dremel.com/storage/en-gb/dremel-200-series-774-original-pdf-19921-en-gb.pdf Instructions]<br />
** Flexible shaft<br />
** 3rd party sets of bits and accessories <br />
::''The green box bits & accessories set is the most complete. The other one is overspill + half worn-out bits. The flexible shaft is now kept off the tool as its rarely used. Please try not to loose the little shaft coupling nut from the tool end of the flexible shaft! The Dremel and its attachments and accessories live in the large translucent plastic crate on the grey shelves next to the cloakroom door.''<br />
* [https://uk.rs-online.com/web/p/multitools/4722782 RS Pro Mini Drill] - 12V drill (max. 17K RPM no load) & Variable speed PSU<br />
** with 3.2 mm (1/8") capacity 3 jaw chuck<br />
** uses Dremel bits, but not fixed accessories<br />
::''Lives with the Dremel in the large translucent plastic crate on the grey shelves next to the cloakroom door. Chuck key is taped to its 12V power cord. A better choice than the Dremel for precision drilling.''<br />
* Set of files (round, square, triangular, flat, half round) - ''On side wall next to Woodworking bench''<br />
* TORX screwdriver set - ''behind Electronics bench, opposite Woodworking''<br />
* Hex key set - Metric & Imperial/US, boxed - ''behind Electronics bench, opposite Woodworking''<br />
* Hacksaws: Junior (6") and full size (12") - ''Hanging up behind the Woodworking bench''<br />
: A full size hacksaw is an effective means to cut metal from 3 mm to over 50 mm thickness. Also useful for hard plastics.<br />
: Our Amtech 12" hacksaw needs four full turns after taking up the slack to tension the blade. Spare 12" 18 TPI and 24 TPI blades are hanging with the hacksaws. The spare 6" blades are in the spare drills box on the power-tool shelves the other side of the window.<br />
: ''There's more to using a hacksaw than you might think - incorrect blade tension or wrong choice of blade for work thickness, can ruin a blade in minutes and make your job much harder and slower. See [https://www.youtube.com/playlist?list=PLZgJvC8P7mk3g9v3mnW1MfpgUWiOkIfwr How to use a Hacksaw] - a 26 m video series covering basics, cutting straight, and how to cut thin metal without damaging the blade - by 'Course You Can' (Jim Garratty).''<br />
<br clear=all><br />
<br />
= Equipment and Tool Defect List =<br />
Stuff that's usually available, but is currently broken, (or recently fixed) should be on our [[Equipment and Tool Defect List]].<br />
<br />
''This is not a 'live' defect list, and tools/equipment may fail unexpectedly between its update and your intended visit.''<br />
<br />
=Computers=<br />
<br />
===Printers and Scanners===<br />
[[Printers_and_scanners]]<br />
<br />
===Desktop computers===<br />
* Windows PC in the office/Laser Cutter room. See [[Laserpc]]<br />
* 2 Linux PCs under 3D Printing bench<br />
* All-in-one Apple Mac next to Electronics bench,<br />
;Other<br />
: Hard drive duplication station [[http://cpc.farnell.com/integral/inssdhddsatacopy/drive-dock-sata-copy-station/dp/CS20331]]<br />
* SIM card cutter (micro and nano)<br />
* Assorted old laptops and old workstations<br />
* Laser printer (mono)<br />
<br clear=all><br />
<br />
=Other facilities=<br />
===The Round Table===<br />
Possible our most important area; a place where people have a cup of tea, chat or do some work<br />
<br />
===Bathroom===<br />
Yes we have one of those. Wheel chair accessible.<br />
<br clear=all><br />
===Kitchen===<br />
[[File: Kitchen2.jpg |200px|right | Kitchen ]]<br />
Kettle, sink, cups a plenty, ... <br />
<br clear=all></div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Blog_2024&diff=17688Blog 20242024-03-27T00:38:35Z<p>IanM: /* 2024-03-26 Tuesday */</p>
<hr />
<div>== 2024-03-26 Tuesday ==<br />
* David came to visit us for the first time and printed a case for his LORA device<br />
* Andrew was looking at 3D printers, helped David and looked at his Pi Camera<br />
* Steve was fixing an alarm clock/radio successfully <br />
* Ian was ably helping Steve and later, diagnosing the blown lathe speed control board<br />
* Paul was coding <br />
* Andy popped in after shooting but went home to get dry<br />
<br />
== 2024-03-19 Tuesday ==<br />
* Phillip came the first time and was shown how to use the Laser<br />
* David returned for his second visit to finish his branch lopper<br />
* Alfia and Raff come alongs to look at engraving some metal with mixed results<br />
* Ananth was looking at a CO2 sensor ably aided by<br />
* Paul who was sharing electronics knowledge as always<br />
* Mark popped by to say hello and be frustrated by his fiddly electonics<br />
* Ian decided to blow up our lathe for fun, but has a plan to fix it as always<br />
* Andrew was working on the 3d Printers <br />
* Andy did an induction and wrote this, all errors mine<br />
* Kevin came to trying lathing but was sadly out of luck<br />
* Vic was using the drill press to create a frame for his home CNC <br />
<br />
== 2024-03-12 Tuesday ==<br />
* Andy came to see us after a long time away to say hello<br />
* Steve was playing with batteries again and also with an alenco set.<br />
* Pierre was seeing if he can get his PTZ camera to move<br />
* Paul was getting frustrated at LED strips online <br />
* Andrew was playing with an LED Matrix on Pi Pico<br />
* Mark came to display hardware that wasn't needed and is currently flummoxed over.<br />
* Ananth trying to get a C02 sensor working and trying understand what Mark is talking about<br />
* Ian was teaching the lathe to...<br />
* Kevin who showed his machining chops on our little lathe<br />
* Andy came to say hello after shooting<br />
<br />
== 2024-03-05 Tuesday ==<br />
This may be a lost week but we had some regulars and some new people coming after an article in a Ham magazine.<br />
<br />
== 2024-02-27 Tuesday ==<br />
*Steve was rescuing batteries from discarded vapes to use in projects and helping...<br />
*Andy working out the hand plane and welcoming people<br />
*Ben was doing some trying to remove some components from an electronics board<br />
*Elliot was designing and lasercutting some pieces for gaming<br />
<gallery>20240227 220255.jpg</gallery><br />
*David came to visit us for the first time with a branch lopper that was in need of repair ably helped by...<br />
*IanM who also helped with general advice and looked at the wood CNC, conclusion is shielding the mains to the spindle is a good first step<br />
*Janet is visiting the UK for a few months and came to visit us, looking at programming a FGPA board with a pico<br />
*Rich was attempting to get Rust onto some lora boards<br />
*Andrew was making more progress with the geetech 3D printer.<br />
*Pierre continued to make his PTZ camera<br />
<br />
== 2024-02-20 Tuesday ==<br />
* Pierre continued with his PTZ mount build, with a laser cut frame on top of a 'Lasy Susan' for rotation and an axle turned down at the ends to fit the bearings which eventually carry the tilting part<br />
<gallery><br />
PierrePTZ.jpg<br />
PierrePTZ2.jpg<br />
</gallery><br />
* IanM was helping people again and introduced Pierre to turning steel on the lathe<br />
* Steve was working on some faulty DC-DC converter modules<br />
*Ananth was examining his previous soldering and making some improvements<br />
*Andrew was helping people with 3d printers including<br />
*Mark came to print a mount for his diving project<br />
*Mat came to 3d print a clasp and do some more designing for the next thing<br />
*AndyH was helping<br />
<br />
== 2024-02-13 Tuesday ==<br />
* Pierre is designing a PTZ camera mount<br />
* Mark has joined the throngs of the laser cutters<br />
* MarkQ came to do some laser cutting<br />
* Andrew journey to fix all the 3d printers continues<br />
* IanM was helping people and doing some lathe work<br />
* Steve continues fixing his light<br />
* Andy opened and did some marquetry<br />
<br />
== 2024-02-06 Tuesday ==<br />
* BenF was laser cutting some signs<br />
* Steve is repairing a shed light powered by a solar panel<br />
* Andrew was fixing 3d printer<br />
* AndyH opened and ran before the road was closed<br />
* ChrisN was 3d printing some more train pillars<br />
* Ian.M was <br />
* PaulE was coding<br />
<br />
== 2024-01-30 Tuesday ==<br />
* Andrew was learning how to setup a raspberry pi, assisted by Andrew<br />
* Chris was continuing some 3d printing and working with Fusion 360<br />
* Mat came to see us and started learning Fusion 360<br />
* Pierre came to learn the lasercutter<br />
* Steve was mending a light and looking at fixing a battery, also helping...<br />
* Kev with some soldering <br />
* Andy did some inductions on the laser for 3 people and gave some limited hints on Fusion<br />
* Andrew was looking at 3d printing and helping setup the Pi<br />
* Paul was coding<br />
<br />
== 2024-01-23 Tuesday ==<br />
Regulars: Paul E, Andy, Andrew, IanM<br />
* Garret came along and was good to see him, looked at fixing a calculator<br />
* Andrew and his son came along for the <br />
* Chris came for the first time and we showed him some 3d printing<br />
<br />
== 2024-01-16 Tuesday ==<br />
Regulars: Paul E, Martin, Andrew<br />
* Anand - CO2 sensor<br />
* Mark - intro to laser cutter<br />
* David - laser engraving, kartcher cleaner that doesn't run<br />
* Cath M - dehumidifier that needs fixing<br />
<br />
== 2024-01-09 Tuesday ==<br />
* Andy opened<br />
* Regulars: Ian M, Andrew, Martin, Paul E<br />
* Steve - assisted a soldering task<br />
* Peter - came for inspiration on a project<br />
* David - laser cutting plywood for a box<br />
* Wendy and Deborah - had a steam cleaner that needed fixing<br />
* Anand - soldering headers on more boards<br />
* Lucas and Zac - introduction to 3D printing<br />
* Catherine - introduction to 3D printing<br />
<br />
== What we have been doing at Little House ==<br />
<br />
Previous years blogs are available from the [[Main_Page| Main Page]]</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Facilities&diff=17685Facilities2024-03-23T13:09:50Z<p>IanM: /* Soldering/Desoldering */</p>
<hr />
<div><!--<br />
New facilites page by Andy (beardedfool)<br />
Problem:<br />
I found RML through the wiki (only discovering the www page after I had visited) and couldn't find what I was looking for easily - what toys you had there. <br />
<br />
e.g. There's an inventory page and a facilities page which seem to duplicate information - but neither link to useful other pages e.g. the laser cutter page.<br />
<br />
Solution<br />
I've had a go at clearing them up. I'd like to 'give back' by creating some instructions for equipment as people are kind enough to show me them (e.g. lathe, laser cutter, CNC, 3D printing)<br />
Tidying these pages is the first step - then I can use this page as a jump off for these instructions.<br />
<br />
As it's a bit presumptious - I've largely kept the content the same at the moment, apart from minor edits for clarity. I suspect it's still not wholly accurate in terms of assets you have, other pages that should be linked or out of date content but hopefully a start<br />
<br />
Testing<br />
As I don't have editing rights to the wiki I put it into https://www.mediawiki.org/wiki/Project:Sandbox by edit source' button and looks largely right but problems with images likely - kept most the <br clear=all> tags in but may be a better way https://en.wikipedia.org/wiki/Template_talk:Clear <br />
<br />
Questions/ next steps<br />
Create repository on your github for this? May be an unwanted layer of abstraction, but as it's code. <br />
<br />
Contact people about Asset database (Dan), Laser Cutter materials (Kim) and other 3D printers (Paul B)<br />
<br />
Add to wiki LHS navigation menu as Facilities; redirect inventory page to this - #REDIRECT [[Facilities]]<br />
<br />
Create other instructions over time<br />
<br />
<br />
Code starts... --><br />
<br />
=Audio Visual=<br />
===Bluetooth-enabled Stereo===<br />
How to use<br />
# Turn on the power switch connected to the stereo to the right of the double-doors. <br />
# Press "VIDEO/AUX" on the stereo input dial (in the middle) to connect it to the Bluetooth receiver. <br />
# On your Bluetooth-enabled smartphone or laptop device, go into your Bluetooth preferences and search for devices. You will see "Belkin HD" as one of the available devices. Pair it with your device and start playing music/podcasts/Internet streams. <br />
# If you do not see "Belkin HD" then power cycle the Belkin device and search again.<br />
<!--<br />
===Plasma screen===<br />
[[File: PlasmaScreen.jpg |200px|right | Plasma Screen]]<br />
Huge screen. Can't miss it. HDMI, DVI, ... sound is the only thing that does not work. <br />
More information [[Panasonic_TH-65PF12EK|here]]<br />
--><br />
<br clear=all><br />
<br />
=CAD - Computer aided design=<br />
===Laser cutter===<br />
[[File: LaserCutter.jpg |200px|right | Laser Cutter]]<br />
<br />
Privately owned Laser cutter (60W) can be used periodically for prototyping. <br />
<br />
[[Laser_cutter|Has it's own page here]]<br />
<br />
''Please do not use the laser cutter until you have received induction''<br />
===3D printing===<br />
We have several 3D printers that can be used to print downloaded models or rapidly prototype your designs.<br />
<br />
Some basics on 3D printing [[3dprinting-basics|here]]<br />
<br />
Our Printers:<br />
<br />
====Flashforge adventurer 3====<br />
[https://www.flashforge.com/product-detail/flashforge-adventurer-3-3d-printer Flashforge's page ]<br />
<br />
====Geeetech I3 pro B====<br />
[[Geetech_I3_Pro_B| here]]<br />
<br />
====Zombie Printer====<br />
A machine so modified it got a new name<br />
* Dedicated page [[The_Zombie_Printer|here]]<br />
<br />
[[File: 3DPrinter.jpg |200px|right | 3D printer]]<br />
<br />
<!--<br />
NB this is all commented out but I want to keep the text as we still have some of the machines<br />
<br />
====BIQU Magician====<br />
* A good machine as an introduction to 3D printers for new-comers. Works well with minimal changes of settings. More here<br />
====[http://www.deltamaker.com/ DeltaMaker] 3D printer====<br />
it is connected to the network via [https://octoprint.org/ octoprint]. <br />
* When you are at little house point your web browser to http://deltamaker.rml<br />
* Login to octoprint with <br />
**user:rml <br />
**password: rml<br />
* ssh <br />
** pi<br />
** deltamaker<br />
<br />
====Geetech Dual Extruder====<br />
Currently only one extruder working<br />
* GT2560 board<br />
====Formlabs 1+ resin printer====<br />
[[https://wiki.richmondmakerlabs.uk/index.php/Formlabs_3d_printer here]]<br />
====Phrozen resin printer====<br />
Web GUI, IP is shown when machine is started. Has a slicer built in<br />
--><br />
<br />
===CNC Machines===<br />
====CNC Mill====<br />
N.B. This is currently not operational<br />
<br />
[[File: CNCRouter.jpg |200px|right | CNC machine]]<br />
CNC Mill - OpenBuilds [https://openbuilds.com/builds/c-beam%C2%AE-machine-plate-maker.2020/ C-Beam CNC Router] <br />
In the cloakroom<br />
<br />
''Please do not use the CNC Mill until you have received induction''<br />
* Instructions on use from Leo [[CncMill|here]] and Nick [https://web.archive.org/web/20210928032955/https://ndevenish.com/2017/01/26/cnc-update.html here (Internet Archive)]<br />
<br clear=all><br />
<br />
====CNC Metal Mill====<br />
N.B. This is not yet operational<br />
<br />
Denford MicroMill<br />
<br />
====CNC Lathe====<br />
Denford MicroMill<br />
N.B. This is not yet operational<br />
<br />
Denford Microturn<br />
<br />
=Crafts=<br />
===Sewing machine===<br />
There is a mini sewing machine from John Lewis on loan from Andres. Feel free to use when ever. It is kept in its box on the gray shelves next to the kitchen. <br />
Follow this video for [https://www.youtube.com/watch?v=eFABAbK4Beo threading] and first steps! <br clear=all><br />
<br />
=Electronics workbench=<br />
[[File:Electronics Bench 2022.jpeg |200px|right |Electronics Bench]]<br />
[[File:20221206 Electronics.jpg|200px|right |Electronics Bench in use]]<br />
See our [[Electronics]] page for notes, tutorial links, etc.<br />
===General===<br />
* Various hand tools, test equipment, wiring, connectors, resistors, capacitors, LEDs and other assorted components<br />
* UV exposure box<br />
* Magnifying lamp<br />
* 'Helping Hands'<br />
** Two positionable clips to hold wires, components and small assemblies<br />
** Magnifier<br />
* Tiltable plastic jawed vice<br />
** for holding small to medium PCBs and small assemblies<br />
** ''Do *NOT* use for assembling IDC cables or forcing a fit - grab a drill press vice from the engineering bench for that!''<br />
<br />
===Soldering/Desoldering===<br />
* Weller WS80 temperature controlled soldering station<br />
** with WSP80 iron (24V, 80W)<br />
** takes [https://docs.rs-online.com/9b2b/0900766b803f878a.pdf LT series tips]<br />
** [https://www.pkelektronik.com/media/downloads/w/e/weller%20loetstation%20ws%2080.pdf Operating Instructions] - Controls/Connections layout on pages 2 & 3, English instructions start at page 23<br />
* <s>Maplin (Precision Gold) temperature controlled soldering station</s> - ''U/S as of 5/10/2022''<br />
** with 24V, 48W iron - ''element failed''<br />
** Chinese OEM: [http://www.china-zhongdi.com/?keyword=ZD-937 Zongdi ZD-937] <br />
** UK source for spares: [https://uk.farnell.com/duratool/d00675/soldering-station-48w-230v-uk/dp/1498364 Duratool D00675 @Farnell]<br />
* Power+ 8000 series SMD Rework Station<br />
** A 'knockoff' of a [http://yihua-soldering.com/product-1-1-1-2in1-hot-air-rework-station-en/147633/ Yihua 852D+] - [https://www.manualslib.com/manual/2488638/Yihua-706-Series.html#product-852%20Series 852D+ Manual]<br />
** Variable temperature and flow hot air tool - ''Missing its hot air nozzles apart from the 6 mm one fitted.''<br />
** 50W temperature controlled soldering iron - Takes HAKKO 900 series tips. <br />
*** The iron is a Yihua 907A clone, five pin GX16 connector, male on the station, female on the iron, [[:File:Yihua GX16.png|Yihua pinout]]. The iron has an A1322 clone element nom. 24V 50W. Tips should be 6 - 6.5 mm OD, and nom. 4 mm ID.<br />
<br />
:: ''N.B. Tips must be a good close fit on the ceramic element, but not excessively tight. Many clone tips are too loose and will need a sleeve to function. If the tip is too tight there is a high risk of breaking the element.'' <br />
<br />
:: ''Yihua knockoffs are not known for their electrical safety. A test sticker indicates it passed in 2018 (probably PAT testing) and the hot air nozzle is grounded, but we should check if there is a reliable ground at the soldering iron socket. See [https://www.eevblog.com/forum/reviews/w-e-p-yihua-852d-combined-hot-air-station-and-soldering-iron/ 852D topic @EEVblog]''<br />
<br />
* BGA re-balling station - [https://www.youtube.com/watch?v=fNxXn32L74o YouTube demo]<br />
** Uses same Yihua 907A type iron as the SMD rework station. <br />
* Solder sucker station - see: [http://www.ameritronics.com/digital_desolddering_de-soldering_stations_tools.htm HOW TO DESOLDER THROUGH HOLE COMPONENTS, CONNECTORS & CHIPS?]<br />
<br />
===Bench Power Supply===<br />
* Thurlby PL320 Bench Power Supply<br />
** dual channel 0-30V, 2A<br />
**[http://www.av.it.pt/medidas/Data/Manuais%20&%20Tutoriais/05%20-%20Programable%20Power%20Supplay%20PL330DP/PL%20Series%20Instruction%20Manual%20-%20Iss%2012.pdf PL series instruction Manual]<br />
<br />
===Pulse Generator===<br />
* AIM & THURLBY THANDAR INSTRUMENTS TGP110 10Mhz Pulse Generator<br />
** [http://www.farnell.com/datasheets/1734341.pdf?_ga=2.28719740.1736682119.1560968692-1735494415.1560968692 datasheet]<br />
<br />
===Oscilloscope===<br />
*Rigol DS1104Z<br />
**4 channel 50MHz Digital Oscilloscope<br />
**[https://www.batronix.com/pdf/Rigol/UserGuide/DS1000Z_UserGuide_EN.pdf Manual]<br />
<br />
===Multimeters===<br />
* [https://dam-assets.fluke.com/s3fs-public/75_77___omeng0900.pdf Fluke 77] DMM (grey, in brown rubber bumper)<br />
** ''N.B. Rotary mode switch detent is very weak, so carefully align pointer with desired mode indication before use.''<br />
* [https://dam-assets.fluke.com/s3fs-public/7x2x____iseng0200.pdf Fluke 77 III] DMM (grey/yellow)<br />
* Various cheap small DMMs - See Big Clive's [https://youtu.be/-QDW0LRQVrY video review/tutorial] <br />
** ''CAUTION: Do *NOT* use the cheap DMMs on live mains circuits''<br />
<br />
''Please carefully check the red test lead is *NOT* plugged in the 300mA or 10A (current) sockets before making voltage measurements, as the Fluke current range fuses are expensive to replace!''<br />
<br />
=== PC/Mac hosted tools ===<br />
* [https://en.wikipedia.org/wiki/LTspice LTspice XVII] circuit simulator is installed on the all-in-one Mac next to the electronics bench. ''<s>(PC version running under WineBottler)</s>''<br />
* Arduino IDE (v1.8.19) is installed on the same Mac.<br />
* An eight channel USB logic analyser ''(Salae Logic 8 clone)'' is available ''(bin on the electronics shelves at the end over the wood store)'', and the [https://sigrok.org/wiki/Main_Page Sigrok] software to support it is installed on the Mac.<br />
<br />
=Makers Equipment=<br />
* Arduino Starter kit<br />
* Funduino kit with loads of sensors<br />
* Raspberry Pi (with Pi Camera)<br />
<br clear=all><br />
<br />
=Engineering/ Woodwork=<br />
<br />
===Bench drill press===<br />
*Silverline 262212 Drill press<br />
**Chuck Capacity 13mm<br />
** 350W<br />
See our [[Drill press]] page for general instructions and its [https://www.silverlinetools.com/en-GB/Product/ProductDetail?ModelName=262212 Manual] for specifics.<br />
<br />
<br clear=all><br />
<br />
===Lathe===<br />
[[File: Lathe2.jpg |200px|right | Lathe]]<br />
In the kitchen. <br />
<br />
Marked as a CJ18A Mini-Lathe from [[https://www.amadeal.co.uk/acatalog/CJ18A-Mini-Lathe-7x14-Machine-100mm-3jaw-Metric-With-Metal-Gears-AMA_LA_CJ18_M_3_MGRB.html Amadeal]]<br />
[[https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Manual]]<br />
<br />
[[Media:Lathe InductionNotes.pdf| Induction Document]]<br />
<br />
Possible upgrades:<br />
*https://www.youtube.com/watch?v=GwT-JQLbNPA<br />
<br />
''Please do not use the lathe until you have received induction'' <br />
<br />
[[User:IanM|IanM]] has written some more detailed [[Ian M's Lathe Notes|notes on using the RML Lathe]].<br />
<br />
===Bandsaw===<br />
N B This is out of action and in need of replacement<br />
<br />
*Nutool HBS230 230mm Two Wheel Bandsaw <br />
**230W <br />
**Similar [https://www.workshopping.co.uk/files/09681ins.pdf Manual]<br />
*Replacement parts:<br />
**Got some tyres from [www.Solenttools.co.uk solent tools]<br />
**Ian got a new blade from ???<br />
<br />
===Jigsaw===<br />
Bosch PST 700E 500W Jigsaw<br />
[https://www.bosch-diy.com/gb/en/p/pst-700-e-06033a0000-v100024162 Manual]<br />
<br />
===Mitresaw===<br />
Erbauer ERB255GS 2000W 10" Sliding compound mitre saw with laser<br />
<br />
===Router (handheld)===<br />
Black & Decker KW850E 1100W </br><br />
[http://2helpu.com/PDMSDocuments/EU/Docs//docpdf/kw850e_uk.pdf here Manual]<br />
<br />
===Planer (handheld)===<br />
Ryobi EPN-6082 600W </br><br />
[http://www.free-instruction-manuals.com/pdf/p41861.pdf Manual]</br><br />
<br />
===Bench Grinder===<br />
Clarke Metalworker CBG 6RZ </br><br />
[https://www.clarkeservice.co.uk/product_manuals/metalworking_bench_grinders.shtml Manual]<br />
<br />
===Belt Sander===<br />
N.B. We no longer have this as the motor broke. Kept as a reminder we need one and for safety warning<br />
*KOBE KBE2714140K<br />
*[https://www.manualslib.com/manual/1229237/Kobe-Sbd370.html Manual] and [https://cromindo.com/uploads/product_info/KBE/271/KBE2714140K_5.pdf here]<br />
**Safety: Please don't use the dust extraction when sanding metal - hot sparks, wood chippings and lots of air equals fire<br />
<br />
===Compressor===<br />
[[File: Compressor.jpg |200px|right | Compressor]]<br />
Mains-powered air compressor with a long air pipe and a few tools, including paint sprayer. <br />
<br clear=all><br />
* Ratchet tap handles<br />
* 0 - 10 BA tap & die set (imperial)<br />
* Broken bolt extractor set (Easy Outs)<br />
<br clear=all><br />
<br />
=General purpose=<br />
* Ultrasonic cleaner (6.5L) - Tank internal dimension: 300 (L) x 150 (D) x 150 (H) mm<br />
* Small screw driver set with prying tool for mobile phone disassembly<br />
* Spanner set 6mm to 26mm - ''In cloakroom, on bathroom door''<br />
* Hot glue gun<br />
* Dremel 200 rotary Multi-Tool (two speed - 15K/35K RPM no load) - [https://www.dremel.com/storage/en-gb/dremel-200-series-774-original-pdf-19921-en-gb.pdf Instructions]<br />
** Flexible shaft<br />
** 3rd party sets of bits and accessories <br />
::''The green box bits & accessories set is the most complete. The other one is overspill + half worn-out bits. The flexible shaft is now kept off the tool as its rarely used. Please try not to loose the little shaft coupling nut from the tool end of the flexible shaft! The Dremel and its attachments and accessories live in the large translucent plastic crate on the grey shelves next to the cloakroom door.''<br />
* [https://uk.rs-online.com/web/p/multitools/4722782 RS Pro Mini Drill] - 12V drill (max. 17K RPM no load) & Variable speed PSU<br />
** with 3.2 mm (1/8") capacity 3 jaw chuck<br />
** uses Dremel bits, but not fixed accessories<br />
::''Lives with the Dremel in the large translucent plastic crate on the grey shelves next to the cloakroom door. Chuck key is taped to its 12V power cord. A better choice than the Dremel for precision drilling.''<br />
* Set of files (round, square, triangular, flat, half round) - ''On side wall next to Woodworking bench''<br />
* TORX screwdriver set - ''behind Electronics bench, opposite Woodworking''<br />
* Hex key set - Metric & Imperial/US, boxed - ''behind Electronics bench, opposite Woodworking''<br />
* Hacksaws: Junior (6") and full size (12") - ''Hanging up behind the Woodworking bench''<br />
: A full size hacksaw is an effective means to cut metal from 3 mm to over 50 mm thickness. Also useful for hard plastics.<br />
: Our Amtech 12" hacksaw needs four full turns after taking up the slack to tension the blade. Spare 12" 18 TPI and 24 TPI blades are hanging with the hacksaws. The spare 6" blades are in the spare drills box on the power-tool shelves the other side of the window.<br />
: ''There's more to using a hacksaw than you might think - incorrect blade tension or wrong choice of blade for work thickness, can ruin a blade in minutes and make your job much harder and slower. See [https://www.youtube.com/playlist?list=PLZgJvC8P7mk3g9v3mnW1MfpgUWiOkIfwr How to use a Hacksaw] - a 26 m video series covering basics, cutting straight, and how to cut thin metal without damaging the blade - by 'Course You Can' (Jim Garratty).''<br />
<br clear=all><br />
<br />
= Equipment and Tool Defect List =<br />
Stuff that's usually available, but is currently broken, (or recently fixed) should be on our [[Equipment and Tool Defect List]].<br />
<br />
''This is not a 'live' defect list, and tools/equipment may fail unexpectedly between its update and your intended visit.''<br />
<br />
=Computers=<br />
<br />
===Printers and Scanners===<br />
[[Printers_and_scanners]]<br />
<br />
===Desktop computers===<br />
* Windows PC in the office/Laser Cutter room. See [[Laserpc]]<br />
* 2 Linux PCs under 3D Printing bench<br />
* All-in-one Apple Mac next to Electronics bench,<br />
;Other<br />
: Hard drive duplication station [[http://cpc.farnell.com/integral/inssdhddsatacopy/drive-dock-sata-copy-station/dp/CS20331]]<br />
* SIM card cutter (micro and nano)<br />
* Assorted old laptops and old workstations<br />
* Laser printer (mono)<br />
<br clear=all><br />
<br />
=Other facilities=<br />
===The Round Table===<br />
Possible our most important area; a place where people have a cup of tea, chat or do some work<br />
<br />
===Bathroom===<br />
Yes we have one of those. Wheel chair accessible.<br />
<br clear=all><br />
===Kitchen===<br />
[[File: Kitchen2.jpg |200px|right | Kitchen ]]<br />
Kettle, sink, cups a plenty, ... <br />
<br clear=all></div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_Lathe_Notes&diff=17682Ian M's Lathe Notes2024-03-14T15:33:19Z<p>IanM: /* Thread Cutting */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br />
<br />
''Currently these notes are semi-organized and non-authoritative. As I become more experienced with the RML CJ18A mini-lathe, I'm cleaning up, extending and reorganising them. Some lathe operating experience is assumed. If in doubt, '''*ASK*''' me, Andy H<sup>*</sup> , Jonathan H or another experienced minilathe operator!<br />
<br />
''* Andy H should be asked (for an authoritative answer) any questions involving RML usage policies or acquiring tooling or materials through RML.''<br />
<br />
== The Lathe ==<br />
Our Facilities page [[Facilities#Lathe|has]]:<br />
<blockquote><br />
'''Lathe'''<br />
[[File: Lathe2.jpg |200px|right | Lathe]]<br />
In the kitchen. <br />
<br />
Marked as a CJ18A Mini-Lathe from [[https://www.amadeal.co.uk/acatalog/CJ18A-Mini-Lathe-7x14-Machine-100mm-3jaw-Metric-With-Metal-Gears-AMA_LA_CJ18_M_3_MGRB.html Amadeal]]<br />
[[https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Manual]] <br />
<br />
[[Media:Lathe InductionNotes.pdf| Induction Document]]<br />
<br />
Possible upgrades:<br />
*https://www.youtube.com/watch?v=GwT-JQLbNPA<br />
<br />
''Please do not use the lathe until you have received induction'' <br />
<br clear=all><br />
</blockquote><br />
Its a Chinese import 7x14 mini-lathe. The 7x14 refers to the maximum diameter and length of work, in inches and is only a theoretical measure of the working envelope as you loose length to the chuck + any tailstock tooling, and the diameter is over the bed, not the cross-slide. See actual specifications below. <br />
<br />
Most if not all Chinese 7x10 to 7x16 mini-lathes seem to be remarkably similar (not uncommon with Chinese products due to [https://www.bunniestudios.com/blog/?p=284 Shanzhai (山寨)] )<br />
and the OEM of our Amadeal CJ18A Mini-Lathe was probably [https://www.made-in-china.com/showroom/cheap-lathe Yangzhou Realbull Machinery Co. Ltd]. Very similar lathes are also made by [https://www.siegind.com/lathe-machine.html Sieg], but their lathes tend to be slightly less sophisticated than the equivalent Realbull models.<br />
<br />
''N.B. Many Sieg parts are known to have slight but critical differences from Realbull parts, so '''DON'T''' order Sieg spares for a Realbull lathe!<br />
<br />
== Key Specifications ==<br />
Amadeal says the CJ18A Mini-Lathe is a 7x14 model with:<br />
<blockquote><br />
* Power 550 W<br />
* Distance between centres : 350 mm<br />
* Swing Over Bed: 180 mm<br />
* Swing Over Cross Slide: 110 mm<br />
* Taper: MT3<br />
* Tailstock Taper: MT2<br />
* Chuck diameter: 100 mm<br />
* Spindle Speed: 50 - 2500 rpm ''(with digital readout)''<br />
* Spindle Bore: 20 mm<br />
* Cross slide Travel: 65 mm<br />
* Range of Metric Threads: 0.5 - 2.5mm.<br />
</blockquote><br />
* The lead screw is metric, pitch 1.5 mm.<br />
* The spindle center is 90.6 mm above the flat of the bed (measured).<br />
<br />
Even though the compound and cross slide handwheels appear to be calibrated in thousandths of an inch, as ours is a metric machine, they only approximate that. One turn of a slide handwheel is 1mm advance, and they have 40 divisions, so each division is 0.025 mm, (approx. 0.984 [https://en.wikipedia.org/wiki/Thousandth_of_an_inch thou]). Similarly, the tailstock quill advances 1.25 mm per handwheel turn, which has 50 division dial, giving the same 0.025 mm divisions, but only 4 turns per 5 mm. The carriage handwheel is awkward - it moves approx. 19.2 mm per turn, and doesn't have a dial scale.<br />
<br />
== Notable Accessories ==<br />
We have:<br />
* [https://www.amadeal.co.uk/acatalog/160mm-Face-Plate-for-the-4-Mini-lathe-AMA_AC_CJ18A_FP160RB.html#SID=129 160 mm (6 1/4") Faceplate]<br />
* 100 mm (4") three jaw self-centering chuck (OEM standard) 22.5mm bore, with inside and outside jaw sets<br />
* 100 mm (4") four jaw (independent) chuck with reversible jaws (8 TPI screws)<br />
* Tailstock drill chuck (max. 13 mm dia.)<br />
* Live center for tailstock (+ OEM fixed center) <br />
* Four way Tool Post (OEM Standard)<br />
* [https://www.amadeal.co.uk/acatalog/Quick_Change_Tool_Post_for_the_mini-lathe.html Quick Change Tool Post] + 3 tool holders<br />
* [https://www.amadeal.co.uk/acatalog/Fixed-Steady-for-Mini-Lathes-AMA_AC_CJ18A_FSRB.html#SID=145 Fixed Steady Rest]<br />
* [https://www.amadeal.co.uk/acatalog/Travelling-Rest-for-Mini-Lathes-AMA_AC_CJ18_TSRB.html#SID=144 Travelling Steady Rest]<br />
<br />
''You'll find all of the above on the shelf above the lathe, with the accessories in the wooden box, apart from the steadies, which live next to it. Change gears, spare parts, and most cutting tool tips/blanks are in labelled white rectangular tins behind the lathe.''<br />
=== Measuring Tools ===<br />
We have:<br />
* Various dial indicators - the one with the adjustable magnetic base stand is the most convenient for most lathe setup work.<br />
* 25mm micrometer (in little grey case)<br />
* Grey case containing set of measurement tools including dial calipers, micrometer, steel rule (metric & inch), engineers square, and a fish-tail gauge<br />
<br />
''We currently lack''<br />
* ''A tool height setting gauge''<br />
<br />
=== Hand Tools ===<br />
Some common tools needed for normal use are kept with the lathe, in or attached to the wooden accessories box:<br />
* 2 mm Allen key - adjusting cross-slide and compound gibs<br />
* 4 mm Allen key - quick change toolholder tool clamping screws + height adjust, tightening dials<br />
* 5 mm Allen key - four way toolpost tool clamping screws, engaging/disengaging threading indicator<br />
* 6 mm Allen key - locking/unlocking quick change toolholder<br />
* 8 mm spanner - locking carriage when 8 mm socket can't be used, locking gib adjuster nuts <br />
* 13 mm spanner - changing chucks, locking steady rest jaws<br />
* Very long needle nose pliers - for grabbing swarf safely, holding one end of emery cloth safely so you can keep your fingers away from the jaws, and extricating small objects from awkward places.<br />
<br />
== Change Gears ==<br />
[[File:BC puller 1.jpg|thumb|Custom puller for B-C stub shaft]] [[File:BC puller 2.jpg|thumb|Pulling the B-C stub shaft]]<br />
See "Conquest Super Lathe" manual ([[#Manuals|below]]), section '''4.7 Change Gears''', PDF pages 28-29, but see below for mesh adjustment. The LittleMachineShop.com "Mini Lathe User’s Guide" (also below) section '''Threading''' gives a far better explanation, with pictures and diagrams, but its for a lathe with a US 1/16 inch pitch leadscrew, not a metric 1.5 mm pitch one like ours, so you *MUST* ignore all the tables in that section, replacing them with metric mini-lathe (with 1.5 mm pitch leadscrew) equivalents. <br />
<br />
We have the following tooth count gears: 20,20, 30, 35, 40,40, 45, 50,50, 60,60, 80,80<br />
which consist of the OEM power feed gears + the metric change gear set. Apart from the metal 20 tooth pinions, they are all plastic, probably Delrin if the molded in 'POM' marking can be trusted, but possibly plain Nylon 6, and are metric Module 1.<br />
<br />
If we wanted to add the capability to cut US/Imperial threads we'd need to buy additional 55, 57 and 65 tooth gears, and possibly a 21 tooth metal pinion.<br />
<br />
CGTK's [https://www.cgtk.co.uk/metalwork/calculators/changegears/minilathe?gears1=20,20,30,35,40,40,45&gears2=50,50,60,60,80,80&gears3= Change Gear Calculator] ''(link preloaded with our gear list)'' is useful if you don't want to calculate the ratios from first principles. Not all suggested combos will physically fit.<br />
<br />
* Take care *NOT* to loose the keys in the A and D shaft keyways - turn each shaft till the keyway is up before removing the gear. <br />
* The B and C gears are coupled by a hollow stub shaft (with an integral key), which is so tight in the gears it has to be pressed or driven out - I've made a puller just for this task, kept in the change gears tin.<br />
* The center of the B-C stub shaft *MUST* be lubricated where it runs on its pin on the change gear banjo bracket, with grease or heavy oil. ''Seizure of the stub shaft due to running dry is a frequent cause of catastrophic mini-lathe geartrain failures!''<br />
* Don't get oil on the change gears as it can cause plastic gears to crack. Only PTFE drylube or plastic compatible white grease should be used on their teeth. <br />
* Adjust the B-C pin position in the straight slot first to set the C to D gear mesh, tighten its nut, then swing the whole banjo about the D shaft boss to set the A to B mesh, and finally tighten the banjo clamping nut.<br />
* Check both gear meshes have running clearance by turning the chuck by hand enough to complete one full turn of the leadscrew, and by attempting to turn the intermediate gear(s) to assess backlash, If excessive resistance is felt or if there's significant backlash, readjust the gears. If you have difficulty judging the mesh, a strip of 80 gsm copier paper (approx. 0.1 mm thick) wound into the meshing teeth before tightening the stud or banjo will give appropriate clearance once removed. Once setup, check the gears run quietly under power.<br />
* If the sum of the tooth counts C+D is the same as for the ones you just removed and they were correctly meshed, you don't need to move the stub shaft pin. If A+B is <u>also</u> the same, you don't need to move the banjo. e.g. If it was set up for 16:1 reduction power feed, 1 mm (40:60 - 50:50) for M6 and 1.5 mm (e.g. 40:60:40) for M10 pitches can thus be achieved by only swapping gears. <br />
<br />
''The change gears, puller, etc. and a box spanner for the banjo nut are kept in a white rectangular tin behind the lathe.''<br />
<br />
=== Power Feed ===<br />
When used for turning with power feed, the change gears should be set for a 16:1 reduction (A:20 : B:80 - C:20 : D:80) using the pair of small metal 20 tooth pinions and the 80 tooth plastic gears (largest in set), for a feed of 0.09375 mm per turn (1.5 mm/16). Unless continuing your threading project the next session, please re-fit the 16:1 power feed set after threading so the power feed is ready for use. <br />
<br />
* *ALWAYS* leave the feed direction selector lever in its neutral (no feed) position, and the half-nuts open after use.<br />
* *ALWAYS* check the carriage lock is disengaged before engaging power feed. Unlock the carriage after use. <br />
<br />
=== Threading Dial ===<br />
The threading dial is an aid to re-engaging the half-nuts at the right moment so the tool will retrace its previous path cutting deeper, rather than offsetting axially some fraction of the thread pitch and ruining your work. Its based on the concept of the lowest integer multiples of the leadscrew and thread ''(being cut)'' pitches that exactly match, but for mechanical simplicity it only covers certain selected multiples of the leadscrew pitch.<br />
<br />
We have a choice of three pinion gears:<br />
{| class=wikitable<br />
|+ Threading dial Pinion Gears<br />
|-<br />
! Teeth !! Colour Dot !! Usable lines !! OD gear !! Dist. per turn<br />
|-<br />
| 14 || Red || 1,7 || 7.51 mm || 21 mm<br />
|-<br />
| 15 || Orange || 1,5,9 || 8.05 mm || 22.5 mm<br />
|-<br />
| 16 || Green || 1,4,7,10 || 8.37 mm || 24 mm (2 mm/div)<br />
|}<br />
They are now colour coded, with a paint dot on the gear end face ''(the only non-wear surface)''. The 16 tooth one is normally left on the lathe, but disengaged when not threading to minimise wear on the lead screw. The others are kept in the Change Gear tin.<br />
<br />
There's a threading dial 'pickup' calculator here: https://www.cgtk.co.uk/metalwork/calculators/threaddialindicator <br />
<br />
Initially select ''Lathe:'' '''Custom''', and enter the following below:<br />
* ''Units:'' '''Metric'''<br />
* ''Lead Screw Pitch (mm):'' '''1.5'''<br />
* ''Thread Dial Indicator Gear Teeth:'' '''16,15,14''' <br />
* ''Lines on Thread Dial Indicator:'' '''12''' <br />
* ''Line Marking:'' '''Every Line Numbered'''<br />
Note the teeth list is entered in reverse order so the resulting table highlights any required pinion changes.<br />
<br />
N.B. The dial is only friction clamped to the pinion by its center screw. If you have any reason to suspect it may not be properly aligned: <br />
# With the power off and the carriage unlocked, engage the feed direction lever upwards. You'll probably need to turn the chuck by hand to get it to engage.<br />
# If the threading indicator isn't already engaged, loosen the threading dial support block bolt, pivot the block to engage the pinion with the leadscrew and retighten the bolt.<br />
# Engage the half nuts, again turning the chuck by hand till they drop in. <br />
# Turn the chuck a couple of turns, top towards you to take up any backlash, then lock the carriage, taking care not to push it left while locking it.<br />
# Loosen the screw securing the dial to the pinion.<br />
# Align the '1' line of the dial with the index line, by rotating the dial clockwise, then retighten the screw.<br />
# Don't forget to disengage half-nuts and unlock the carriage!<br />
<br />
The above instructions should result in the half-nuts engaging cleanly when exactly on any valid line when threading towards the headstock. If it is required to thread away from the headstock, there will be a slight offset from the line due to backlash between the spindle gear and leadscrew, so engage slightly early.<br />
<br />
Changing the pinion:<br />
# Loosen the threading dial support block bolt and disengage from the leadscrew.<br />
# Undo dial center screw, and remove it and the dial, dropping the old pinion out the bottom.<br />
# Oil the shaft of the new pinion with a drop of light oil and insert it from below, gear end down.<br />
# Refit dial and screw.<br />
# Check the dial and pinion turn freely with minimal resistance.<br />
# Align as above.<br />
<br />
== Tailstock and Steadies ==<br />
These are mostly used to support long work ''(long with respect to its diameter)'' to improve rigidity, increasing accuracy and reducing chatter. The Tailstock quill is also used with a drill chuck for drilling.<br />
=== Tailstock ===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock base]]<br />
The tailstock can be offset to turn shallow tapers between centers. We don't currently have the accessories to turn between centers, namely <s>a MT3 dead center for the spindle, or</s> any drive dogs for the work. Also realigning the tailstock after turning a taper can be a PITA. The photo shows the tailstock adjusting screw locations ''(C - Lateral, and D - Skew)'' and the block on the baseplate they engage with. Adjustments can only take effect when the tailstock locking lever is eased to take the pressure off the baseplate. As we don't have a MT3 center, one has to turn a fresh point on a test workpiece for a rough tailstock alignment reference. Fine alignment, to avoid inadvertent taper turning, can be done by mounting a long precision ground bar between the chuck (or preferably a center in the spindle), and a dead center in the tailstock and sweeping it with a dial indicator on the carriage. Finally a test cut should be taken at either end of a bar between centers, and the diameters checked with a micrometer. Assuming the bed has previously been properly levelled and shimmed to take out twist ''(not the case at RML as we don't have it bolted down)'', any remaining difference in diameter will be double the tailstock offset, smaller at the tailstock being offset towards the front. Fine adjustment cant be achieved by jacking with the screws, its best to ease the adjusting screws, bump the tailstock into alignment then take up the screws again, checking the alignment is maintained when the tailstock is unlocked and relocked. There is no vertical adjustment, though shims can be added between the tailstock and its base.<br />
<br />
==== Tailstock Quill ====<br />
There is a metric/imperial scale on the top of the quill, read against the end of the tailstock, for depth measurement when drilling. The tailstock quill has a 1.25 mm pitch thread and a 50 division dial. Each division is therefore 0.025 mm, and it only takes 4 full turns of the handwheel to move the quill 5 mm. <br />
<br />
To eject MT2 taper tooling and centers from the tailstock, wind the quill all the way in.<br />
<br />
N.B. The quill anti-rotation pin (dog-tip setscrew + locking nut in top of tailstock near to the quill lock) is only M5. It will sheer if a large diameter drill jams in the work. Please back it out clear of its keyway if using large drills, and use alternative methods of preventing chuck rotation. To re-engage it, crank the quill out till you can see the keyway, align it with the screw and screw in the screw till it gently bottoms out, then back it off a quarter turn. Try twisting the quill to check its properly engaged, then tighten the locking nut gently to hold the screw in position clear of the bottom of the keyway.<br />
<br />
=== Steady Rests ===<br />
We have two, both with brass tips that must be kept lubricated during use.<br />
<br />
The fixed steady mounts on the ways, and is most useful when turning longer work that wont fit through the spindle bore. Adjustment is critical, and the surface the tips run on must be smooth and concentric, as any misalignment that forces the work off center will result in the work wobbling in the chuck, marring it, with a high risk of it becoming un-chucked, which can be dangerous at speed.<br />
<br />
The travelling steady mounts to the headstock side of the carriage to locally resist the deflection of thin long work, due to the cutting forces. It only has two tips, to resist climb, and deflection away from the tool, and requires readjustment after every cutting pass.<br />
<br />
== Tooling and Tool Holders ==<br />
'''Key dimensional data:'''<br />
* The quick change holders accept up to 10 mm shank tools. <br />
* The four way toolpost has 50 mm long sides, a seat width of 15 mm and can clamp tools of up to 5/8" (15.875 mm) shank ''(check this)'', but the slot base is only 10.4 mm below the spindle center so cannot be used with >10 mm shank tooling unless it has a dropped tip. Large tooling with a centered tip is also problematic as you run out of height above the shank when trying to shim to match the spindle center height. <br />
<br />
===Quick Change Toolpost===<br />
I've got the quick change toolpost and toolholders setup for mostly easy use. The three toolholders came with cantilever height setting arms which historically haven't been installed as the supplied fixing screws were too short. That's all now sorted out and a HSS RH turning tool and a HSS hand-ground grooving/parting-off tool are now mounted in two of the holders and set to height. The third is kept free for other tools. <br />
<br />
The quick change toolpost has been modified with a spring to press the dovetail clamp outwards and help stop it twisting or flopping about to ease toolholder fitting and removal. The dovetail clamp (socket headed screw on toolpost side opposite dovetail) feels a bit stiffer than before, but will take less than half a turn to go from open (with the toolholder lifting out or dropping in easily) to fully clamped. As there is so much less clearance in the open position you should no longer need to wiggle the toolholder while clamping it to get a consistent height. If the dovetail clamp ever gets misaligned, twist it straight by eye, slacken off a bit further than usual to get a toolholder on, clamp it to align the dovetail then release, reseat the toolholder and re-clamp to ensure its at its preset height. You cant adjust the height by 'jacking' with the height screw due to its offset leverage. Instead, back off the height screw and hold the toolholder at the desired height while locking the dovetail clamp, then adjust the height screw (and locking nut) to hold it there, then check it doesnt change height significantly when you unclamp and reclamp the dovetail. <br />
<br />
Unfortunately the OEM height setting screws foul the toolpost locking nut handle. Currently, if you need to swap toolposts you will have to first remove the quick-change tool holder from the post. There is enough nut handle swing to allow the quick change toolpost to be unclamped and rotated to fine set the tool angle without removing the toolholder. It also seems the mating surfaces may be slightly out of square, as if you rotate the toolpost 90° or 180°, the nut swing may be insufficient to re-clamp it without removing the toolholder to do so. Add a M10 washer under the locking nut if the handle ends up pointing in an undesirable direction! A thin M10 washer is kept with the toolpost collar for this purpose, and will shift the handle position by about a third of a turn. <br />
<br />
''ToDo: Make a taller nut of a similar pattern, to clear the height setting screws.''<br />
<br />
===Four Way Toolpost===<br />
The OEM four way toolpost is significantly more rigid than the quick change toolpost + holders because it has fewer and thicker parts and less overhang. Therefore the four way toolpost should be used when using carbide tooling. It requires shimming under the tool to set the tip height to the spindle center height - see below. The tool shanks are mostly significantly less than 15 mm wide, so need to be centered under its clamping screws, tempting as it is push the shank in for full side contact with the toolpost. If possible clamp the shank with all three screws not just two.<br />
<br />
==== Shimming ====<br />
We typically only mount up to two tools, and want maximum rigidity, so use 50 mm x 15 mm shims, (the full seat area), preferably with deburred edges and radiused corners so they aren't a hazard to the operator.<br />
<br />
We have pre-cut and marked shims of the following thicknesses: <br />
* 1x 3.23 mm, 2.42 mm, 1.56 mm, 0.32 mm, and 0.25 mm<br />
* 2x 1.00 mm, 0.77 mm, 0.12 mm, 0.11 mm, 0.10 mm and 0.05 mm<br />
* 4x 0.53 mm<br />
<br />
Our shims are mostly found materials (hence the awkward thicknesses) and are mostly a mixture of aluminium and steel, with a couple of GRP ones. The toolpost seat '''<u>must be absolutely clean</u>''' to avoid embedding debris in the aluminium or GRP shims, to get a consistent height and avoid tilting the tool - wipe it every time you change a tool! Put the thin shims at the bottom of the stack to avoid the tool shank edges creasing them. Shims are kept in a little yellow plastic box with a clear lid, near the carbide tools case.<br />
<br />
I made a tool height setting gauge (T shaped black acrylic with steps in its sides) which can be used to check the tool tip height matches the spindle center height using either the flat of the ways or the saddle as a reference. The tool tip should just fit under the lip of the appropriate step, with the T arms across the ways flats or on the saddle. It is kept in the box with the carbide insert tools.<br />
<br />
''ToDo:'' <br />
<br />
* ''Cut more shims neatly, mark them with their thickness.''<br />
* <s>''Do test cuts and start noting shim stack-ups for various tools.''</s><br />
* ''Organise shim storage!''<br />
<br />
=== HSS Tools ===<br />
[[File:Tool Bit Geometry.jpeg|thumb|Single point cutting tool geometry]]<br />
Our HSS tools are made from 8 mm square bar stock, hand-ground to tip profile in-house. See LittleMachineShop's [https://littlemachineshop.com/images/gallery/instructions/grindingtoolbits.pdf Grinding Tool Bits] notes. <br />
<br />
I've installed our usual HSS LH turning and parting off tools in two of the quick change holders and set the heights correctly. There are a couple of other HSS tools or tool blanks knocking about. Taking heavy cuts turning steel (even with good cutting oil) blunts HSS tools fairly quickly, which are time-consuming to re-sharpen nicely without a dedicated tool & cutter grinder with appropriate jigs. Its worth noting that the usual 'speeds & feeds' tables are commonly based on surface speeds expected to give a half hour (active cutting) tool life before resharpening.<br />
<br />
I touched up the LH turning tool by lapping on wet & dry (silicon carbide) paper on glass (Aka: [https://en.wikipedia.org/wiki/Scary_sharp 'Scary Sharp']) working upwards through the grits 200, 400, 600 and finally 1000, initially 'bluing' the surfaces to be lapped with a marker pen to see which areas needed taking down more. The end of the tool was significantly uneven so I touched that up freehand on the bench grinder to flatten it when it became apparent that 200 grit lapping wasn't cutting where it needed to. There was an existing micro-bevel on the leading side, which I kept. Finally I 'dubbed' the leading corner vertical edge on the 1000 grit to give it a very slight nose radius. A test cut on brass gave a very nice finish when turning.<br />
<br />
''Ian B has purchased some spare 8mm HSS tool blanks - talk to a lathe trainer if your proposed lathe work needs custom ground HSS tooling.'''<br />
<br />
=== Brazed Tungsten Carbide Tools ===<br />
Somewhat of a half-way house between hand ground HSS tooling and insert tooling with the disadvantages of both and some more besides - e.g. they are much harder to sharpen. So why do we bother? Some tool geometries would be awkward and tedious to hand grind, and Chinese import brazed carbide tooling is about half the price of similar HSS tooling, and far more readily available. Also, for space constrained tooling like boring bars, if you want carbide, for insert tooling, the size of the insert and its clamping seriously limits the minimum hole diameter you can work in. I have purchased a set of 3/8" shank brazed carbide tipped boring bars, but we currently cant sharpen them, due to lack of a diamond grinding wheel. <br />
<br />
=== Tungsten Carbide Insert Tools===<br />
Decoding ISO insert tooling part numbers: https://www.cutwel.co.uk/blog/learn-the-turning-tool-iso-code-system<br />
[[File:Carbide set.jpg|800px|thumb|left|Our set of Tungsten carbide insert lathe tools (before the new inserts were fitted)]]<br />
<br />
{| class=wikitable<br />
|+ Tools, left to right, (+ last across top):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| SSKCR0610H06 || 75° through boring || SCMT06204 || Long || 6 || 6.34 || ''4.33''<br />
|-<br />
| SSSCR0610H06 || 45° deep facing, internal chamfering || SCMT06204 || Long || 6 || 6.13 || ''4.58''<br />
|-<br />
| SWUCR0610H05 || 93° boring, deep facing || WCMT050308 || Long || 6 || 6.22 || ''4.48''<br />
|-<br />
| SWGCR0810E05 || 90° RH turning & facing || WCMT050308 || Short || 8 || 8.25 || '''2.45'''<br />
|-<br />
| SSSCR0610E06 || 45° turning, chamfering || SCMT06204 || Short || 8 || 8.75 || ''1.93''<br />
|-<br />
| SSBCR0610E06 || 75° RH turning, chamfering || SCMT06204 || Short || 8 || 8.72 || ''1.98''<br />
|-<br />
| LW0810R-04 || 60° external threading || JCL15-120 || Short || 8 || 7.44 * || ''3.28''<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || 8.23 || ''2.5 ?''<br />
|-<br />
| LN0813R-04 || 60° internal threading || JCL15-120 || Long || 7.95 || 7.44 * || ''3.28''<br />
|}<br />
<br />
{| class=wikitable<br />
|+ More Tools, (loose in tin):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || ~8.5 (not in use) ||<br />
|-<br />
| [https://www.glanze.co.uk/product/glanze-12-mm-60-degree-metric-internal-threading-tool/ Glanse SIR0012K11] || 60° internal threading bar || 11IRA60 || Long || 12 dia || ??? || ???<br />
|}<br />
''Shim stack heights in bold are tested, in italic are only calculated.'' ''Tip heights marked * are with new JCL15-120I inserts. The single remaining plain JCL15-120 insert has a slightly higher tip height.''<br />
<br />
Carbide tooling typically requires two to three times more speed than HSS and at least a couple of 'thou' depth of cut for best results.<br />
<br />
Chatter can rapidly kill carbide tooling by chipping the cutting edge. To improve rigidity and reduce the risk of chatter, the cross-slide and compound gib screws need to be well adjusted so there is minimal play in the slides, tool stick-out should be minimised, the four way toolpost should be kept over the cross-slide, and the work should be kept close to the chuck (or otherwise supported by tailstock or steady rest) to avoid excessive deflection.<br />
<br />
Thermal shock is almost instant death to carbide, and when dry cutting the insert tip can run very hot, so do not add extra cutting fluid manually during the cut. Pre-apply what you need, evenly, before starting the cut.<br />
<br />
Parting off or facing to center is high risk - if the tool tip is even slightly below center or if tool or work deflection takes it below center, the work will tend to climb over the tool tip as the cut approaches center, breaking the insert. To avoid this, the tool should be shimmed slightly above center, sufficient to allow for work and tool deflection, and unless very close to the chuck, a steady should be used. Its often preferable to part to a couple of mm dia. remaining then stop and saw through the remainder, then clean up by facing. Parting off hollow parts is much lower risk.<br />
<br />
Further investigation of the Tungsten carbide insert tool height situation is not encouraging - the so-called 'set' in question does not have a consistent tip height ''(see above table)''! In a real set, the insert seats *should* be machined allowing for the insert thickness to bring all the cutting edges to the same height with respect to the shank underside. However if you place them tip to tip on a table its easy to see there is considerable height variation, so they need to be individually shimmed (or at best, one machined shim will only be right for two or three tools). At this time we don't have dedicated shim stacks for each tool.<br />
<br />
A 2.42 mm thick shim brings the SWGCR0810E05 90° RH turning & facing tool almost exactly to center height, and good results were obtained turning 1" steel pipe. However facing 50mm steel bar stock to center found it to be slightly low, leaving a fractionally under 0.05 mm 'pip' so it needs another 0.03 mm to bring it fractionally above center. Fractionally too high is generally preferable to fractionally too low, due to tool deflection, so adding an 0.05 mm shim to the stack should produce optimum results.<br />
<br />
==== Inserts ====<br />
Ian B has purchased the spare inserts we needed in sets of five. He even was able to get the CK3 parting-off inserts which had been difficult to source!<br />
<br />
Inserts used in above tool set:<br />
* 3x SCMT06204 (square, indexable) https://www.rdgtools.co.uk/acatalog/SCMT-06-Carbide-Insert.html<br />
* 2x WCMT050308 (triangular, indexable) https://www.rdgtools.co.uk/acatalog/WCMT-05-T3-08-5XTIP-8813.html<br />
* 2x JCL15-120 (60 deg threading point) https://www.rdgtools.co.uk/acatalog/X5-JCL-15-120L-THREADING-TIPS-60-DEGREE--X5-TIP---23455.html<br />
* CK3 (parting off) https://www.rdgtools.co.uk/acatalog/CK3-CARBIDE-TIPS---PARTING--BOX-OF-5PCS--9437.html<br />
<br />
Inserts used in other tools:<br />
* 1x CK3 (as above) also missing from spare parting off tool<br />
* 1x 11IRA60 in Glanse threading bar + 1x spare<br />
<br />
=== Drills ===<br />
Various sizes of center drills are kept in a plastic bag next to the wooden accessories tray. There's also a small box of 2.5 mm center drills.<br />
<br />
We have a set of 11 TiN coated HSS drill bits from 1.5 to 8 mm, (in a cylindrical plastic index box) for tailstock drilling of brass, aluminium and non-abrasive plastics. To keep them sharp enough for the precision work we expect from the lathe, please don't use them for steel or reinforced plastics, and don't borrow them for non-lathe use. Metric and US [https://littlemachineshop.com/reference/numberdrillsize.php numbered]/[https://littlemachineshop.com/reference/letterdrillsize.php lettered] general use HSS drill bits are kept in two red metal index boxes next to the drill press.<br />
<br />
== Using the Lathe ==<br />
=== General ===<br />
Making dimensioned parts is primarily done by touching off the tool tip on a reference surface (with the lathe stopped, turning the chuck by hand), zeroing the handwheel dial, then manually counting turns and divisions. When backing off the tool its best to do so by exactly one whole turn so you don't forget the previous dial position. Stopping and measuring the work before taking the final cuts is essential if high accuracy is required. ''I've changed out the dial setscrews for flat tip ones with a tiny slug of solder under them so the dials are now friction fit on their shafts. i.e. if you hold the handle firmly taking up the backlash in the direction of cut, you can zero the dial just by grabbing and twisting it.''<br />
<br />
Carriage movement is less easy to measure as the handwheel is uncalibrated and advances an awkward bit over 19.2 mm per turn. Your options here when shoulders or other features must be exactly positioned are, in order of increasing accuracy: <br />
* Use measuring instruments, scribe the work at the desired length then work to the scribed line. Its often convenient to black the work with a permanent marker, then scribe with the tool tip, turning the chuck by hand.<br />
* for short distances, lock the carriage and use the compound, set parallel to the work<br />
* Set up a long travel dial indicator to measure carriage motion. <br />
N.B. with the leadscrew stopped, and the threading dial engaged, with its default 16 tooth gear, it will make one turn for every 24 mm of carriage movement (2 mm/div). This isn't accurate enough for positioning but is sufficient to check you aren't out by a whole mm or more.<br />
<br />
Do not allow any solvents to contact the chuck guard clear plastic as it will make the plastic brittle, or even craze it, and try to avoid melting it with the work light!<br />
<br />
===Speeds & Feeds===<br />
The surface speed of the tool relative to the work (or visa versa) is important, and best results will be achieved when it is in a tool type and material specific range. Because the surface speed is proportional to the diameter and the spindle RPM, it is usual to vary the spindle speed in inverse proportion to the diameter to get the surface speed in the desired range, and keep it there as the tool tip moves closer to the spindle axis. <br />
<br />
A cutting speed chart for HSS tooling, published by Model Engineer magazine can be found [https://www.model-engineer.co.uk/sites/7/documents/cutting%20speed%20chart.pdf [here<nowiki>]</nowiki>]. The second row is the target feed rate and the rest of the chart, apart from the diameter column is RPM.<br />
<br />
For carbide tooling cutting iron and steels, recommended speeds are generally three times higher than for HSS, but the CJ18A 2500 RPM max. spindle speed (in high gear) means you can only reach the optimum speed range for over 15 mm dia work. For small diameter work, HSS tooling may well be a better choice.<br />
<br />
An online metric speeds calculator is here: https://www.cgtk.co.uk/metalwork/calculators/cuttingspeeds <br />
<br />
How to do the maths to calculate speeds and feeds: https://www.cutwel.co.uk/blog/speeds-feeds-made-easy<br />
<br />
If you can hear the lathe 'sing' as it cuts, you are getting chatter, which invariably results in poor surface finish. Try decreasing (or possibly increasing) the spindle speed till the resonance stops. <br />
<br />
Once you have a wavy surface due to chatter, a light cut wont clean it up as the tool 'twangs' from peak to peak. You have to take a deep enough cut to get under it. For precision parts, its therefore desirable to take a trial finish cut while still 0.5 mm or so oversize, to give an opportunity to tweak the cut to get a good finish, check for taper, and that the part wont be undersize (on your test finish cut nominal diameter).<br />
<br />
=== Slide Locks ===<br />
* The carriage can be locked to the ways using the M5 hex screw through the top of the saddle to the left of the cross-slide. Double check the leadscrew is disengaged and the half-nuts open before locking it. Lock it when facing.<br />
* The cross slide can be locked by a M4 socket headed cap screw just in front of its middle gib screw. Locking the cross slide is helpful when turning very shallow conical features where the cross slide handle is in the way of the compound.<br />
* The compound slide can be locked by a M4 socket headed cap screw in line with the edge of the toolpost mount on the side with the gib adjustment screws. In normal use it should be kept backed off half a turn but it is desirable to tighten it for parting off operations to keep the resulting end faces flat.<br />
<br />
=== Compound ===<br />
The compound consists of a locking swivel and a top slide allowing cuts to be made at an angle to the axis e.g to produce bevelled or tapered features. There is a difference between US and UK usage, in the US a compound angle of 0° means the compound slide is parallel to the cross slide, but in the UK, 0° is parallel to the ways. The compound angle indicator on the CJ18A follows UK practice, 0° parallel to the ways, but it is not to be trusted, its out by a few degrees!<br />
<br />
One of the deficiencies of the CJ18A lathe is the difficulty of setting the compound angle. It is held and locked by two screws hidden under the top half of the compound slide, which must be wound back till its toolpost end is clear of the pivot point to access them. This may have to be repeated several times to snug them up enough to tap it to the desired angle, then finally tighten them. <br />
<br />
We generally keep the compound slide set approximately parallel to the ways so it can be used for short-distance longitudinal positioning without measuring. However it is unlikely to be closely parallel unless a test bar has been swept with a dial indicator on the slide, or test cuts made on a large OD workpiece and checked for taper.<br />
<br />
=== Chucks and Chuck Jaws ===<br />
==== Terminology ====<br />
* Inside jaws have steps on the outside to grip the ID of hollow work, but can also be used as outside jaws on small diameter parts (i.e. that fit through the spindle). <br />
* Outside jaws have steps on the inside to grip the OD of the work.<br />
* Universal chucks have a scroll plate with a spiral screw thread that moves all the jaws.<br />
* Independent chucks have individual adjusting screws for each jaw.<br />
<br />
==== The Chucks ====<br />
* The three jaw universal chuck can only grip near round or hexagonal work, which it centers, but its concentricity is not perfect so e.g. if you reverse the work and continue turning at the same diameter from the other end, you will see a line where the turned surfaces meet. It has separate sets of inside and outside jaws, and we normally keep the inside set installed to use as outside jaws for small diameter work.<br />
<br />
** Our jaws are individually numbered, stamped in the groove. They must be fitted in the correct sequence. The jaw slots are not clearly marked. Lowest runout for small dia. parts is achieved if you fit the jaws with #1 anticlockwise of the makers mark, then continue anticlockwise for #2 and #3.<br />
** A large strong rubber band is a great help getting all the jaws started on the scroll together - with slots #1 and #3 above the centerline and the scroll thread outer tip between #1 and #3, insert jaws #1 and #2 and put the rubber band round them to keep them in their slots. Insert jaw #3 and stretch the rubber band over it to hold it up into its slot. If the scroll was positioned correctly, all jaws should be at the same initial radius. The jaws can now be cranked in with the chuck key and they should all engage in step so they meet in the middle.<br />
:: ''Mini-lathe.com have the best instructions for [https://www.mini-lathe.com/mini_lathe/chucks/chucks.htm#Installing_Chuck_Jaws changing the jaws].'' <br />
<br />
* The four independent jaw chuck can grip most roundish or squarish work, which can either be carefully centered by the user, or deliberately gripped off-center. <br />
** Its jaws are reversible so can be swapped from inside to outside by simply cranking each jaw out and reinserting it the other way round, one at a time. DON'T move the jaws to different slots as they are likely to bind.<br />
** When setting up to face the sides of rectangular objects held crossways, it may be helpful to use both inside and outside jaw orientations, in symmetrical opposing pairs.<br />
** Its screws move their jaw 1/8" (3.125 mm) per turn<br />
<br />
* The jaws must '''never''' protrude from the chuck OD by more than one step, and for safety, its preferable they don't protrude at all, as they make the gap between the front of the bed and the chuck body an even more unforgiving meat grinder, and as the number of teeth engaged with the scroll or screw decreases, they loose strength, just when you need it the most to grip larger/heavier work. <br />
<br />
''Neither chuck is well suited to gripping tapered work safely. When seating work that doesn't quite fit through the chuck bore (which is larger than the 20mm spindle bore limit), be careful that it isn't seating on the chamfered edge of the chuck bore as it is far to easy to get the work slightly cocked so it doesn't run true.''<br />
<br />
==== Changing Chucks ====<br />
* When changing chucks, use the small grey plastic mat to protect the ways under the jaws in case you drop the chuck.<br />
* The spindle nose has two patterns of holes - the three hole pattern is for the three jaw chuck and the faceplate, and the four hole pattern is for the four jaw chuck. One hole is shared between the patterns, and is marked on the spindle nose.<br />
* To fit a chuck:<br />
** First check that the spindle nose and chuck back and recess are free of swarf, grit or other debris. Any foreign objects will tilt the chuck causing excessive runout and may mar the surfaces.<br />
** Remove the nuts and split lock washers from its studs, line its studs up with the hole pattern (preferably with the stud nearest anticlockwise to the makers mark through the marked spindle hole), fit and hold it in place with your right hand, and with your left, get the lock washer and nut on the top stud, and take up the slack.<br />
** One one nut is on, you no longer have to worry about dropping it, and can work round fitting the remaining washers and nuts, taking up the slack on each as you fit it. <br />
** Next, work round again getting them all finger tight, then tighten them gently, and finally work round fully tightening them. <br />
* Removal is the reverse of refitting. Put the washers and nuts back on the chuck's studs so they don't get lost.<br />
<br />
==== Gripping Threaded Work ====<br />
It is generally undesirable to chuck work gripped on a screw thread, as it is difficult to hold the work securely and get good concentricity while avoiding crushing the thread crests. However, if one must, one of the better ways of doing so is to wind a wire helix to fit the thread then clamp on the outside of the wire so it seats on the flanks of the thread. The wire should be mild steel or soft iron for steel parts and copper for aluminium and brass parts, single strand, round and of uniform diameter a little less than the thread pitch. It can be wound on the lathe, in reverse, by chucking a sacrificial mandrel of the same diameter and thread pitch, hooking the end of the wire round or under the jaw, against the direction of rotation, then holding the other end of the wire under tension with pliers and starting the lathe dead slow. Once wound and removed from the mandrel, the ends must be trimmed then it should be screwed on to the threaded work to provide a surface to chuck on.<br />
<br />
=== Faceplate Work ===<br />
Faceplate work is probably the most dangerous operation you can (or rather should) perform on a lathe. The working area is a large diameter spinning surface with protruding clamps to fixture the part that it is impractical to guard. Protruding clamps, studs, nuts etc. are very difficult to see at speed.<br />
<br />
'''Treat the faceplate with great respect and caution if you wish to continue to be able to count to ten on your fingers!''' <br />
<br />
The 65 mm cross-slide travel vs the 80 mm faceplate radius is a serious limitation that may require creative compound, toolpost and tool setups for larger parts, and doing full face cuts in two sections.<br />
<br />
''It is common practice to skim the faceplate to ensure it runs true. We have not (yet) done this, and wont till the spindle is in better bearings and the nose reground to minimise runout.''<br />
<br />
==== Clamping ====<br />
Open ended/sided clamps should be oriented so that cutting forces drive the work towards the clamping bolt/stud, not out from under the clamp. Minimize the protruding length of thread past the clamping nut, if necessary using sacrificial bolts or studs you can cut to length, or even using a long M8 stud for one of the faceplate mountings, so you can get a clamp nearer to the faceplate center. Double-check all clamps are secure, manually turn the faceplate to check the work and clamps clear the ways, top-slide and toolpost, and stand out of the 'line of fire' (a disc extending from the faceplate) when spinning up the work for the first time. <br />
<br />
If you need to machine close to a clamp, consider marking a safe limit circle on the faceplate and work with a marker pen to make it easier to see how close the cutting tool is to crash disaster. <br />
<br />
I strongly advise reading chapter two of Tubal Cain's book "Workholding in the Lathe" several times before your first faceplate setup, and if possible get another experienced lathe user to check your first few setups before spinning them up.<br />
<br />
==== Chuck Guard Removal ====<br />
The faceplate is too large diameter to fit under the chuck guard, but the guard has an interlock switch wqhich must be closed for the lathe to run. The guard is now fitted with wing nuts so it can be removed allowing the the interlock switch to close when using the faceplate. It *SHOULD* *ALWAYS* be refitted if a chuck is fitted, except when turning work too large to clear the guard. <br />
<br />
''The chuck guard is primarily there to make it very difficult to start the lathe without removing the chuck key and to reduce the area of large diameter spinning surface exposed. It may slow down the projectile if a chuck sheds a jaw but is unlikely to stop it. Also it serves to contain coolant spray spun off the chuck. As we don't use flood coolant this usually isn't an issue for us. As setting up for faceplate work doesn't use a chuck key, and the most hazardous zone is the face of the faceplate, with its spinning projecting clamps, with full access required for machining operations, which a guard would not cover, the consensus is that removing the guard is an acceptable risk.''<br />
<br />
=== Turning and Facing ===<br />
We are getting good results in aluminium, brass, and even steel using HSS cutting tools in quick-change tool holders, and the ~ 94 um/turn power feed. Unfortunately due to lack of rigidity in both the machine and smaller diameter parts, if you don't want the outer end to be over diameter, a light final cut and multiple 'spring' passes will probably be required.<br />
<br />
For aluminium, a sharp HSS tool and 0.5 mm (20 div) depth of cut gives good results with power feed for rapid stock removal. Its also easy maths as each cut takes ~ 1 mm off the diameter. Finish cuts should be much finer, 0.1 mm (4 div) is 'in the ballpark'.<br />
<br />
For steel, using carbide insert tooling, a 0.25 mm (10 div) depth of cut is more appropriate, and with pre-applied cutting oil, gives reasonable results with power feed if you use enough speed. The maths is not quite so easy as you are only taking 0.5 mm off the diameter per pass. Again, use finer finish cuts but try to plan your cuts so the final cut is still cutting, not smearing the surface!<br />
<br />
When facing or parting off, some skill is required to turn the cross-slide handwheel steadily to get a decent finish and to avoid shock-loading the tool tip. Increasing the spindle speed in one or more steps to keep up with the reducing diameter is advisable, but avoid speeds that cause resonances (resulting in chatter). When parting off, small through-hole parts may be caught on a thin rod chucked in the tailstock, and pre-positioned inside the work with its tip right up to the parting off position.<br />
<br />
==== Using the Steady Rests ====<br />
For the fixed steady rest, see Blondihacks' Lathe Skills #26 - How To Use a Steady Rest! [[#Youtube_Playlists_&_Videos|{below}]]<br />
<br />
Ours doesn't have ball bearing fingers, so a smooth surface on the work and adequate lubrication are essential. The thumbscrews can only tighten the fingers, so for small adjustments outwards you need to either slack off the clamping nuts or ease them slightly and use a drift against the back of the finger's slot. Once set, check the chuck still turns freely.<br />
<br />
The traveling steady rest needs to run on a machined surface, so at least for the first pass, must follow the tool, so its difficult to avoid using more compound slide overhang than is desirable. An initial surface should be cut next to the chuck or tailstock center before fitting the steady rest.<br />
<br />
Both are a PITA to fit - the fixed one has to have its clamping post inserted up through the bed, and the supplied spanner is useless near the headstock, and the travelling one's mounting holes on the saddle almost invariably need swarf picked out of them.<br />
<br />
==== Turning Between Centers ====<br />
<s>Using a MT3 to MT2 reducing sleeve, the MT2 dead center can be fitted in the spindle.</s> ''Currently the MT3 spindle taper is compromised.'' Alternatively, a soft center can be turned immediately before use in the three jaw chuck, but that must have its 60° point re-cut to concentric if the chuck is disturbed, and needs to be either large enough to bear on the chuck body, or must have a lip to bear on the end face of the jaws to take the axial thrust. Recutting the center is a PITA, as the compound angle must be set to 30° anticlockwise, then reset to a true 0° afterwards. Maybe a right-hand 30° end angle zero rake form tool is the answer, or use the carbide insert tool SSKCR0610H06 as a form tool with the toolpost rotated 15° anticlockwise.<br />
<br />
With the MT2 live center in the tailstock quill, this gives us a center either end of the work to hold it.<br />
<br />
We also need a drive dog similar to [https://littlemachineshop.com/products/product_view.php?ProductID=4473&category=1 this], and the corresponding drive post to bolt to the spindle nose. I have some 25mm bore thick wall iron pipe, which should do nicely. Lengths of the dog's straight tail and of the post TBD after I check how much the center protrudes. N.B. its recommended to tie the tail to the post to keep them in contact so they don't slam. ''Currently we will need to drive from the chuck jaws. Possibly use the exterior jaws with a short soft center gripped on the inside end and drive from the highest step.''<br />
<br />
=== Drilling ===<br />
Always start with a center drill so deflection of longer bits doesn't start the hole off-center. For larger bits (> 5 mm), first drill to the web size, then to final diameter. For a precision hole, drill slightly undersize and ream to final diameter. ''Supply your own reamers!''<br />
<br />
Caution: See note about the quill anti-rotation pin in section [[#Tailstock Quill|Tailstock Quill]] above.<br />
<br />
=== Boring ===<br />
Caution: As the spindle doesn't extend right through the headstock housing, if boring in a through hole, chips tend to fall out the back and tumble in the spindle bore till they fall into the change gears. To avoid this, one should plug the spindle bore with a wad of paper towel or rag and when cleaning up afterwards, use a rod to push it through towards the tailstock, with the chuck jaws (if fitted) wound clear of the spindle bore.<br />
<br />
A swivel bladed hole deburring tool (pale blue handle) can be found in the main room on the windowsill behind the drill press.<br />
<br />
A couple of boring jobs have been bodged with an awkwardly angled turning tool and achieving acceptable effective rake with enough clearance to reach deep enough into the hole has been problematic. I reviewed the tools we had and found none suitable for starting out in a 13mm bore, the max diameter we can (easily) drill. I therefore decided to buy a set of boring bars and make a holder for them. I had difficulty finding anything affordable under 10mm shank - the best low cost option was a [https://www.amazon.co.uk/dp/B07P5LGVBX set of nine 3/8" (9.525 mm) shank brazed carbide tipped boring bars], which would be close to the max capacity of the quick change boring bar holder - if we had one! Unfortunately this holder for our specific toolpost is difficult to find except in a toolpost bundle. Another annoyance is the variable tip height of the set, varying from 1.8 mm to 2.8 mm above the center of the shank.<br />
<br />
I therefore decided to make a boring bar holder of the [https://littlemachineshop.com/products/product_view.php?ProductID=1700 Littlemachineshop.com (USA) style] for use in the four way toolpost, as the additional rigidity will certainly help. Starting with a slightly over 50 mm length of 16 mm aluminium square bar and using the four jaw chuck , both ends were faced and an attempt was made to find its center and center drill it. It was then drilled out to ~9.8 mm after much drama due to blunt drills and drills that cut ~1mm oversize. Too big, but beggars cant be choosers as we didn't have a boring bar holder or a 3/8" reamer. Unfortunately the final hole ended up significantly off center. It was then chucked crossways and ~1 mm skimmed off its thickest side to gain clearance to allow it to be shimmed to height, then one side was slit lengthwise manually with a hacksaw.<br />
<br />
It was fitted to the for way toolpost and loaded with a booring bar, which clamped firmly. A 0.86 mm shim stack brought the tip of the largest boring bar almost spot on center height, with the difference easily accommodated by twisting the tool slightly. The three jaw chuck was then remounted, and a piece of iron pipe chucked for a test. It cuts well and leaves a decent surface finish.<br />
<br />
''The boring bar setup is a work in progress - talk to me before attempting to use them if you have a project that would benefit from boring..''<br />
<br />
ToDo: get something that can sharpen tools tipped with this grade of carbide - it needs some sort of diamond (or possibly CBN) wheel as green grit silicon carbide does little more than polish it. ''N.B. diamond wheels are rapidly eroded by grinding steel, so the supporting steel seat must be undercut with a regular grinding wheel before the diamond wheel can contact it.'' <br />
<br />
We'll also need 50 mm square sheet shims to fit under the toolpost to gain clearance in the toolpost above the tool or toolholder. A 2.4 mm shim would give us about the same above and below spindle center height, and we probably need a small selection of thinner ones.<br />
<br />
=== Thread Cutting ===<br />
The objective is to cut a thread that complies with the ISO metric thread profile. Our lathe is not currently equipped to cut non-metric threads, (with the exception of BA which have pitches based on metric threads of that era).<br />
<br />
[[File:ISO and UTS Thread Dimensions.svg|frame|center|Metric Thread Profile - from the geometry, H is ~86.6% of P]]<br />
<br />
Metric thread data - See 'Preferred Sizes' at: https://en.wikipedia.org/wiki/ISO_metric_screw_thread<br />
<br />
See "Mini Lathe User’s Guide" section '''Threading''' for general techniques *ONLY*, and above for change gears and threading dial setup.<br />
<br />
Amadeal specify the max. thread pitch as 2.5 mm. Any thread pitch greater than 1.5 nn requires the change gears to gear up. When gearing up it is desirable to distribute the ratio as evenly as possible over the two pairs of gears in the geartrain to avoid excessive tooth loading, with the larger driven gear (if different) on the D shaft.<br />
<br />
==== External Threading ====<br />
Initially turn work to required Major Diameter, set up change gears and threading tool, touch off on the work, zero the top and cross slide dials, and do a 'scratch' pass to check the pitch. Back off the tool using the cross slide, return the carriage, and re-engage the half nuts on a valid dial line clear of the end of the thread then immediately stop the lathe, and hand turn the chuck till the tool tip is (hopefully) over the scratch to check the thread pickup. If all is good, return the carriage again, restart the lathe, bring the tool back in and start cutting your thread. <br />
<br />
Methods of doing so vary depending on the size of the thread and toughness of the metal, but straight-in plunge cutting is generally to be avoided as has the highest cutting forces, and does not reliably keep the carriage (and top-slide if set parallel to the work) loaded to avoid pitch errors due to backlash. It is common practice to set the compound angle so the cross slide is nearly parallel to the trailing flank of the threading tool tip, so all the cutting action is at the tip and leading edge. The angle should be fractionally steeper so the trailing flank rubs slightly to avoid deflection. Use a side notch on the fishtail gauge, held against the work, to set the tip exactly straight in to the work. <br />
<br />
After each pass, back the tool out using the cross slide, return the carriage to the start and bring the tool back in to exactly the same cross slide position, before advancing the compound by the depth of the next cut. The depth of cut must decrease as the thread depth increases as the width of the cut increases proportionately to the total depth, which would otherwise result in excessive cutting forces.<br />
<br />
If leaving the half-nuts engaged and reversing the lathe to return to the start of the thread for the next pass, its absolutely essential to back the tool out of the thread for the return pass as it will not follow the path of the cutting pass due to backlash in the geartrain, leadscrew mounts and half-nuts.<br />
<br />
==== Internal Threading ====<br />
''<nothing here yet>''<br />
<br />
== Cutting fluids ==<br />
=== Why bother? ===<br />
[https://youtu.be/mRuSYQ5Npek Watch this video] and contemplate what's actually happening to that thin ribbon of metal being removed. Most of the lathe's motor power is being turned into heat by internal friction in the chip being removed in the zone around the cutting edge, and surface friction at, and immediately behind the cutting edge, near-instantly heating the chip by up to several hundred degrees. Reducing the surface friction using a suitable cutting oil reduces the strain on the machine as a whole, and reduces workpiece and tool heating (and thus expansion) with consequent improvements in maximum usable feed and depth of cut, surface finish and accuracy. It also drastically increases the life of the cutting edge.<br />
<br />
=== Practicalities === <br />
We don't have a coolant system for the lathe and *really* don't want the maintenance hassles of using soluble cutting oil/coolant as if used infrequently its a PITA to keep recirculated high water content cutting fluids from going rancid and stinky, and they can also rust the ways, so even a total loss gravity feed system is problematic. Therefore if dry machining doesn't give a good enough finish, we tend to use oil applied topically, by hand to the work. <br />
<br />
* Hard brass is typically free-turning without oil, however some light oil for the final cut can improve surface finish, but with the disadvantage that it will increase loose chip buildup on the tool as hard brass typically forms short spalls or splinters rather than curly chips.<br />
<br />
* Many Aluminium alloys tend to be gummy, and Paraffin or other mineral spirits mixed with a little oil can help prevent the aluminum welding to the tool edge. WD40 will do at a pinch, but its messy to apply from a spray can.<br />
<br />
* Steel really needs *GOOD* cutting oil. Lard oil is the traditional choice for steel. If there are any objections to lard oil, we should bite the bullet and get some commercial dark high Sulphur cutting oil, but beware, many such oils use an additive package that includes lard oil.<br />
* Cast iron (except ductile) should be cut dry, as the carbon micro-inclusions self-lubricate it, and the carbide in the dust (primarily Cementite) are very abrasive, so tend to form a grinding compound if mixed with oil. <br />
<br />
I've sorted out an oil pot lid with a 1/2" brass collar soldered in to give a nice smooth sided hole, for ease of use and to minimize the risk of spills when using a brush to apply cutting oils, and got some dirt-cheap brushes. It fits Shippam's paste (and similar own-brand spread) jars and I've found several jars and ordinary lids to seal them for storage. Unfortunately it isn't the easiest to get this type of jars' lids back on square so they seal properly, and if you over-tighten them and there's a temperature change, they can be a total <expletive> to reopen. Using the rubberised handles of a large pair of pliers to grip the jar lid just above its rim is the best option, and avoids damaging the lids.<br />
<br />
''N.B. For the smaller brushes, the glue holding the bristles in is attacked by paraffin. To prevent loss of bristles, crimp the aluminium ferrule of each new brush of this type before use.''<br />
<br />
We have, in labelled jars:<br />
<br />
* Sulphurised Lard oil thinned with paraffin. Best choice for heavy cuts and threading in steel but stinky.<br />
* Lard oil thinned with paraffin. Good for steel and acceptable for softer copper alloys<br />
* Paraffin with a trace of light oil. Good for aluminium, and can help prevent squealing chatter on finish cuts in brass.<br />
<br />
I've also got some paraffin wax (in the form of a stubby candle), which can be applied lightly (under power) to brass and aluminium stock especially on the finish pass. It makes less mess than oil but unfortunately tends to build up on the tool tip, making it difficult to 'work by eye' without frequent pauses to clean the tool tip.<br />
<br />
We've also got a tin of [https://www.rocol.com/products/rtd-compound Rocol RTD cutting compound], which is a thick paste. Its highly recommended for drilling and tapping steel (in the drill press or by hand), but as a paste, is less useful for general lathe work unless thinned to a fluid consistency, e.g. with paraffin or white spirits. OTOH its certainly worth trying for high speed facing steel as it is less likely to get flung off.<br />
<br />
== Cleaning and Maintenance ==<br />
Swarf is a significant cut hazard to the operator, especially stringy swarf from cutting steel. Never touch it bare-handed - always use a tool e.g. a brush, or a hook, or needle nose pliers for grabbing long swarf.<br />
<br />
* After use, brush all swarf off the toolholder, compound and cross slide etc. ways and leadscrew, brushing towards the rear to avoid sweeping chips under the carriage. Ian B has blocked off the opening at the headstock end of the rear splashguard (to try to keep swarf out of the motor), so one must sweep the swarf towards the open tailstock end and catch it in the metal dustpan. Preferably, also thoroughly clean out the chip tray under the lathe, but at least sweep out visible swarf.<br />
* Wipe up any cutting fluid residue and re-lubricate affected sliding surfaces with way oil.<br />
* Do not solvent clean the chuck guard, as it will make the plastic brittle, or even craze it. Water with a little detergent is permissible for cleaning it, with the guard totally removed from the lathe.<br />
<br />
Before engaging the half-nuts for power feed/threading, check the leadscrew is clean! ''Best cleaned under power, with a toothbrush.'' <br />
<br />
'''Caution:''' The traverse gears behind the carriage handwheel are in an open-backed housing and tend to become packed with swarf! Swarf buildup here will result in jerky carriage movement. Clean out as much as you can with a toothbrush ...<br />
<br />
===Lack of lubrication and/or swarf or dirt build-up can be disastrous===<br />
* If using the change gears/power feed, lack of lubrication of the B-C stub shaft center pin or either leadscrew end bearing can result in seizure and immediate destruction of one or more gears in the gear train or worse. <br />
* Small pieces of swarf can get between the saddle and ways, or into the slides degrading accuracy, possibly permanently if hard swarf scores them, or jamming them. The carriage handwheel gears behind the apron are notorious for accumulating swarf, and swarf buildup on the leadscrew can prevent the half-nuts engaging properly, resulting in scrapped work, and possibly stripped half-nuts. <br />
* Metal swarf can get into the motor (''though Ian B has modified the rear chip catcher to reduce the risk)'' or into the control box via the leadscrew, and short-circuit stuff. At best it will blow the fuse and need a strip-down to clean it out, at worst it may require a replacement [https://www.amadeal.co.uk/acatalog/Speed-Control-Circuit-Board--12amp-AMA_SP_CJ18_SCB12.html#SID=12 speed controller] ''(currently £96)'' and/or [https://www.amadeal.co.uk/acatalog/550W-motor-for-CJ18A-Mini-Lathe-467.html#SID=240 motor] ''(currently £105)'' and possibly other electrical parts. We should probably fit a [https://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C3-Mini-Lathe-Spares/C3-256-Leadscrew-Grommet-Dustproof-Cover C3-256 Leadscrew Grommet] to keep swarf out of the control box, as it tends to drop onto the 'Filter' board which is mounted horizontally, below the leadscrew.<br />
* Grit from grinding, sanding etc. forms a grinding paste with the way oil, and will rapidly wear out the ways, saddle and slides. Keep grit off at all costs e.g. by covering the ways and slides during grinding/sanding operations, and if there's any chance grit has gotten where it shouldn't, clean and re-lubricate *BEFORE* moving the carriage or slides, then move the carriage and slides, wipe down where they were with a clean paper towel and check there's no remaining traces of dirt other than clean way oil on the paper towel. If it doesn't come clean when you re-lubricate and move it again, a full strip down may be required to solvent clean and relubricate the precision sliding surfaces.<br />
* Although a metalworking lathe *can* be used to turn hardwood, wood dust and small chips are extremely pernicious, as they get everywhere, even clinging to clean surfaces, are abrasive due to their silica content, and are hygroscopic, promoting rust. An even more thorough clean-up than after using abrasives is needed, immediately afterwards. Oily wood dust and fine wood chips in significant quantities are a fire hazard, even in the trash bin.<br />
<br />
===Lubrication===<br />
See section: "Lubrication" in LittleMachineShop.com "Mini Lathe User’s Guide" [[Ian_M's_Lathe_Notes#Manuals|(below)]]. As we usually only open two nights a week, in the table on page 16, Daily lubrication becomes Weekly and Weekly becomes Monthly.<br />
<br />
===General Maintenance===<br />
* The grubscrews holding the cross-slide and compound slide dials tend to loosen due to vibration and use of the dials. Keep them snugged up, but not so tight the dials cant be set without an Allen key.<br />
<br />
* The screws holding the cross-slide nut tend to work loose due to vibration. Crank the handle to and fro through the backlash and visually check there is no movement of the screw heads in their holes. If there is, see the [[#Excessive_cross-slide_backlash|notes below]].<br />
<br />
===Removing the Carriage===<br />
Its possible to remove the carriage from the bed for cleaning etc. without dismantling it. The only stop to its motion is the righthand leadscrew bearing.<br />
<br />
Start by removing the tailstock. Crank the carriage to the tailstock end then remove the leadscrew bearing (two screws and a nyloc nut on the leadscrew end). With the half-nuts open, hold the leadscrew centered in them and crank the carriage off the end of its rack, then slide it off the end of the bed.<br />
<br />
Refitting is the reverse of removal, except (if its gibs are correctly adjusted) the carriage will be very tight on the end of the bed ways so may be difficult to work onto the ways without a stack of blocks of wood or similar to support it at exactly the right height. The righthand leadscrew bearing must be refitted with the carriage as close as possible to it and the half-nuts firmly closed to support the leadscrew at the correct height to hold it in alignment while the screws are being tightened. The nyloc nut controls leadscrew end-play. Fully tighten it then back it off slightly till the leadscrew turns freely with its change gear removed.<br />
<br />
If the Apron has been off, refit it with the screws no more than lightly finger tight and only finally tighten them after checking lead screw engagement at both ends of the carriage travel and that the rack and pinion operates smoothly over the full travel.<br />
<br />
== Issues and Annoyances ==<br />
As of September 2023 - mostly resolved, apart from the spindle bearings and runout, the lathe is in better condition than it has been for a number of years.<br />
<br />
===Four Jaw Chuck has two jaws too tight===<br />
Fixed 27/10/2023: Two of the chuck jaws were tight in their slots, making precise adjustment difficult due to lack of 'feel'. Moving the jaws round the slots showed the problem mostly followed the jaw not the slot. The grooves in the opposite sides of the affected jaws that run in the chuck slots were slightly out of true, and the rails either side of the slots were slightly too thick towards the center. Due to the difficulty of seeing the high spots, after cleaning up and deburring the jaws didn't do enough to ease them, I decided to grind the top of the rails where they were binding. Several repetitions of spotting with Engineer's blue, grinding, then diamond filing the high spots has eased them enough. I cleaned everything, greased the jaw slides and screws, and refitted the studs so the chuck is now fit for service.<br />
<br />
''N.B. Don't move the jaws to a different slot - the formerly tight jaws *must* stay in the slots furthest from the makers mark.''<br />
<br />
===Excessive Runout===<br />
Mostly fixed 24/10/2022: I ground the chuck seating surface of the spindle nose (outside lip) to under half a thou runout. This also cleaned up several burrs. It would be possible to do better, but that would need good spindle bearings, and a more rigid toolpost grinder mount.<br />
<br />
Our spindle nose was damaged years ago by a person with little mechanical aptitude (who shall remain nameless) beating it up with a hammer mushrooming the spindle nose. We are getting several thousandths runout at the end of the MT3 bore, a MT3 to MT2 reducer sleeve in it runs visibly out of true, as does the spindle nose flange. When you put a chuck on it, the runout is magnified by the distance from the spindle nose. Ideally we would replace the spindle when we change the bearings but its £52 [https://www.amadeal.co.uk/acatalog/4-Spindle-Upgrade-Real-Bull-Mini-lathe-CJ18-series-AMA_SP_CJ18_003RB.html#SID=9 from Amadeal] and money is tight. It may well require more work after the bearing upgrade. Once good bearings are in, if we can borrow a decent MT3 arbour as a reference, we should consider skimming the bore.<br />
<br />
===Spindle bearings===<br />
* The spindle bearings appear to be close to worn out. They are notably noisy when running, and there appears to be more slop in the spindle than is desirable. There is notable resonance around 600 RPM, and surface finish of end faces is often poor. We have some ideas for possible replacement/upgrade, but it requires a major teardown.<br />
<br />
: The original bearings are allegedly 6206-2RS or 6206-ZZ deep groove ball bearings - 2RS codes rubber seals both sides and ZZ codes metal shields. Although the deep groove gives reasonable ability to withstand axial loads, the bearing balls point contact means they are vulnerable to [https://en.wikipedia.org/wiki/Brinelling brinelling] due to shock loading. The jammed on three jaw chuck didn't help this, as before we skimmed the spindle nose lip, it had to be driven off using a bar through the spindle bore, shock loading the bearings every time. Also even a minor 'crash' could have brinelled them due to eccentric shock loading, and the lathe has previously been crashed badly enough to need drive gear replacement. There are also issues with the 'approved' method of spindle and bearing removal from the headstock brinelling them, even if you don't abuse the spindle nose with a hammer!<br />
<br />
: A possible replacement is 30206 tapered roller bearings. The new bearings are slightly thicker so the plastic spindle spacer (15) needs to be machined to length to get the 45 tooth spur gear that drives the change gears laterally aligned with the tumbler gears. If a temporary replacement (3D printed?) is fitted, the lathe can be run (without power feed capability) so this can be done on the lathe after fitting the new bearings. As tapered roller bearings have line contact, they are significantly more resistant to brinelling.<br />
<br />
: ''See [[Talk:Ian_M%27s_Lathe_Notes]] for notes, links etc. for this upgrade.''<br />
<br />
===Motor stuttering===<br />
* Fixed 21/09/2023: The motor was running very erratically and it was very difficult to set a speed. Several loose connections were found in the control box, mostly loose female spades to the motor controller board, but also a dry jointed braking resistor on the 'Filter' board, and an inhibit wire completely off its terminal on the forward/reverse switch, making intermittent contact. After tightening and/or remaking all affected connections, it was much improved but still not right below 300 RPM. The remaining issues were due to poor wiper contact in the speed control pot, and stripping it, cleaning the track and contact ring and re-tensioning the contacts resulted in the motor now running smoothly over the full speed range. The speed is slow to settle, and while part of that is probably the lag in the digital tach, I suspect that the KBIC motor speed controller isn't properly tuned as it was (allegedly) previously replaced.<br />
<br />
===Drive belt slipping===<br />
* Fixed 28/9/2022: During testing the motor after the above issue, it was noted that the chuck could be stalled, slipping the drive belt, with not much torque. The drive belt was determined to be loose and a bit worn, but still in acceptable condition. <br />
<br />
: Access for servicing the belt requires removing the control box ''(2 spades to ZVR switch disconnect the supply, speed sensor and motor simply unplug from the 'filter board')'', the motor cover, chuck guard switch assembly + wiring cover, the change gear 'A' (drive) shaft carrier assembly, and the tumbler gear assembly. See https://youtu.be/EkxlIz01BdA for disassembly/reassembly, though on our lathe, the speed encoder ring on the spindle prevents the belt cover from being fully removed without disturbing the spindle nuts. There is enough room to work with it loose, but still trapped by the encoder ring. Also, unlike the video, if the 'jack' screws under the headstock are correctly adjusted, and the studs aren't excessively bent, there is no need to make custom studs. <br />
<br />
: It turns out that our lathe was missing the M6 hex headed jack screws that press the motor down to resist the belt tension, and the motor had cocked out of position at a severe angle. I know Ian B had had considerable trouble adjusting it after the motor fault back in October 2022, and I believe it had been getting slowly worse ever since. The jack screws were probably mistaken for headstock fixing bolts during disassembly after the crash that resulted in the metal Hi/Lo gears being fitted, then lost. The penny washers on the studs had dished, so I turned them over and backed them up with smaller washers and switched to Nyloc nuts so they cant back off due to vibration. N.B. There is a packing washer on the motor side on one of the studs, presumably so the shaft is true to the ways. Adjusting the motor is awkward to say the least. One has to slack the stud nuts off a lot, pry under its rear end to lift it enough to be parallel to the ways, snug the stud nuts, check alignment, then set the jack screws and their lock nuts to hold it there, and finally tighten the stud nuts. <br />
<br />
: Tension: According to Sieg, it should be possible to twist the belt 90° mid span with a light finger grip. Other sources say 1/32" - 3/32" deflection mid span with light finger pressure.<br />
<br />
===Speed display blanking===<br />
* The speed display has been intermittent, blanking and flashing 8888 and 0 at certain speeds for as long as I have been using the lathe. Finally on 18/07/2022 it failed completely, with no display. I removed the display module and bench tested it - the pins are labelled 5V GND PL PE, PE is frame ground and PL is a TTL level pulse from the speed sensor - confirming that it was in good working order. My suspicions then turned to its power supply on the 'Filter' board. With both the sensor and display unplugged, the 5V rail was found to have a only a couple of volts, but the unreg DC was 17V and stable. Replacing the 78L05 5V regulator restored the 5V rail and normal operation.<br />
<br />
: ''I conclude its been failing for a while with high load current due to speeds with more lit segments causing it to drop out, resetting the speed display, causing it to blank, lowering the current enough for the regulator to recover, then the display MCU lamp tests (8888) then re-acquires the speed, repeating ad-nauseum till the speed is changed. I don't like the design as the high input voltage results in excessive dissipation.'' <br />
<br />
: ''ToDo: If it fails again, bench test display to measure its worst case current consumption, then fit an appropriate dropper resistor to reduce the 78L05 dissipation.''<br />
<br />
===Quill spinning when drilling===<br />
* The quill was tending to spin while drilling because its anti-rotation pin (a M5 dog tip setscrew) was sheered. I've removed the debris, aligned the scale with the top of the tailstock and fitted a longer M5 dog-tip setscrew to replace it, with a nut to lock it at the correct height. N.B. the pin isn't that 'meaty' so if using big drills in tough metals, to prevent shearing it, it should be backed out so the quill can be turned by hand and unwanted rotation controlled by being quick with the quill lock if it starts to spin, or even using a close fitting rod in one of the chuck key holes with plastic tube over it to protect the ways. <br />
: ''If the screw sheers again, the quill will need to be removed and the tailstock taken off the lathe so the sheered tip can be shaken out, and if the setscrew is difficult to remove it probably means the threads are mangled where it sheered. Try driving it right through with the quill out.''<br />
<br />
===Sloppy quick change toolpost locking mechanism===<br />
* Once the dovetail clamp screw was slackened, there was nothing preventing the dovetail twisting or cocking significantly, and friction with the toolholder made it tend to do so, making toolholder insertion and removal more difficult unless the clamping screw was backed off excessively. I added a compression spring around the clamp screw inside the toolpost to push the dovetail outwards so it mostly retains alignment when open, allowing toolholders to slide on or off cleanly with far less screw slackening.<br />
<br />
===Leadscrew rubbing===<br />
* The leadscrew shaft is rubbing on the insulating separator inside the control box. Unfortunately the corner of the relay on the Filter Control Board (#160) doesn't allow enough clearance. Although the friction isn't much of a problem at high reduction ratios, e.g. 16:1 power feed, it increases the stress on the change gear train, and may be problematic when threading at feeds above 1:1. ''Possibly pack out the control box mountings by a couple of mm.'' <br />
<br />
===High/Low lever backwards!===<br />
* The high-low drive gear selector behind the headstock is incorrectly labelled and differs from the manual: low gear (which we normally use) is with the lever towards the tailstock. ''I suspect that the gears in the headstock were refitted the wrong way round when it was upgraded to metal gears.''<br />
<br />
: ''ToDo: Get it reassembled the right way round during the spindle bearing upgrade!''<br />
<br />
===Carriage lock fouls top slide===<br />
* The T handscrew has been replaced with a M5 hex headed bolt, to permit access when the top slide is over it. An 1/4" drive 8mm socket is usually left on it, but needs to be removed when the full cross slide travel is needed. The small (4 jaw) chuck key is near enough 1/4" to use for it. If you need to (un)lock it while the compound is over it, you'll need an 8mm spanner. ''The [https://www.amadeal.co.uk/acatalog/Mini-Lathe-Carriage-Lock-463.html Amadeal lock screw] is in the spares tin as it was too high and fouled the compound slide.''<br />
<br />
===Tailstock locking lever loose===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock - See full image for key to screws]]<br />
* Diagnosed and fixed 10/1/2023 - In the base of the upper section of the tailstock, there are two dog tip set screws that engage with locating grooves in the counter-rotating shafts carrying the eccentric locking cams. They'd backed off, probably due to vibration. They need to be tightened till they bottom out in the groove, making sure they are '''in''' the groove, backed off half a turn so the shafts can turn easily, and locked in place. There's no facility to do so, so reassemble with weak threadlocker. Unfortunately to get to them you have to remove the tailstock base slide, which is held on by the pressure of four adjusting grub screws, which all need backing off, and one socket headed bolt from underneath so full tailstock realignment is required after reassembly, which even for a rough alignment is tedious.<br />
: <s>The tailstock locking lever is loose and can be pulled out on its axis. It works OK when fully pushed home but needs investigating. ''I tightened the grub screw as the lever was coming off its shaft, but the whole shaft pushes/pulls in and out. It works OK fully pushed in, but it seems something that is meant to retain it has failed inside the tailstock base.</s><br />
<br />
===Gear alignment issues===<br />
* Change gear alignment is poor. I've currently got a gapped washer (to clear the key) packing out the A shaft so the gears line up, but this reduces the key's engagement so is problematic due to the high loading if the gears are set up for coarser threads. <s>Also I need to turn down some penny washers to slightly less than the root diameter of the metal 20T pinions, as gear retaining washers.</s> ''The gear retaining washers for A gear and B-C stub shaft are now done, turned down to slightly under 16 mm dia. Spares in the change gear tin. ToDo: The D (leadscrew) washer requires a larger center hole, so make two more with that hole.'' <br />
<br />
===Saddle gibs loose===<br />
* Fixed 11/04/2023: I took the apron off for access (and to clean the carriage handwheel gears), and found the front sheer plate screws were completely loose. I've snugged them up some and set the opposing grub screws and got a lot of the slop out. I've re-checked the front ones, and taken up the slop in the rear ones - Unfortunately it wasn't possible to get carriage movement to have an even 'feel' over its whole travel, and its noticeably tighter near the tailstock. If light hand pressure on the side of the unlocked carriage can cause movement (with the half-nuts open), its time to readjust them again, though it should be possible to move the carriage with a firm push. <s>The saddle gibs (actually the sheer plates) were too loose, to the point that engaging a slightly stiff threading dial could cause it to self-feed, an obvious crash hazard if working near the chuck or a step in the work.</s><br />
<br />
''N.B. the lefthand front opposing grubscrew is short, (fully recessed) and unlike the others does *NOT* have a locking nut as it must clear the traverse pinion. A wrap of PTFE tape provides enough friction to keep it in place, though possibly a bit of nylon fishing line down its hole would be better.''<br />
<br />
===Excessive cross-slide backlash===<br />
* ''Fixed 21/11/2023.'' Originally, back in October 2023, The cross-slide screw had excessive backlash (nearly three turns), which increases the risk of loosing track of the cut depth when cutting steps, and during threading operations. If you ended up off by a turn too far in, a crash would be the most likely outcome.<br />
: The original excessive backlash was traced to loose cross-slide screw nut mountings. The nut has two socket headed cap screws pulling up, one either end, accessible from the top of the cross-slide, which control the tilt of the nut to take up backlash in the nut, and an opposing grub screw pressing down on the center of the nut to make it longitudinally rigid. Snugging up the grub screw reduced the backlash to 10 divisions or so, or 0.25 mm. A year later, the backlash had increased to one turn due to the cross-slide nut mounting screws working loose again.<br />
<br />
: 07/11/2023: I investigated further: It is difficult to get the cross-slide nut aligned correctly as it must be at the same height as the screw which is constrained by the bearing surfaces in the bracket. With the cross-slide almost at the front limit of its travel, I removed the screw and set the nut as level as possible and visually centered in the bore, then re-fitted the bracket and screw, then adjusted the tilt till it turned freely through the backlash. I then tilted it up at the front till some drag was felt to minimise the backlash and tightened the screws to lock it in place balancing them to maintain the same feel as I tightened them. The result was 7 divisions of backlash, acceptable but not great. During normal turning operations, the load on the nut is tension on the front screw and pressure on the grubscrew, so if it slackens again due to vibration from chatter, odds are it will be the rear screw that's loosened.<br />
<br />
: 16/11/2023 - 21/11/2023: The backlash had crept back up to 11 divisions (0.275 mm). We don't have any >14 mm brass stock (or even near that) so I tried making the shim washer out of aluminium. I was shooting for 0.24 mm but due to poor technique got 0.28 mm. No good - locked solid. I lapped it down and tried it till I got it down to 0.20 mm which gave about 3 divisions backlash - good enough, but the screw was too tight due to the shim washer not being bevelled at its outer edge resulting in it cupping in its seat. Filing a bevel round the OD and re-lapping it resulted in a 3 - 4 divisions of backlash. Its a little mushy due to the washer having been kinked removing it, so ideally a new (brass) washer should be made. <br />
<br />
* Further reduction of backlash: https://youtu.be/Wu_tI29JL2Y?t=163 <br />
: Brass tinned with Pb-free solder to form a white metal bearing surface should work at least as well as the bronze used in the video. The shim washer needs to be 10.2mm ID, with a full thickness bevel on a 14 mm OD. It isn't necessary to remove the lead screw from the cross slide, as the washer can be fitted in-situ with only the bracket removed.<br />
<br />
===3 Jaw chuck didn't mount properly===<br />
* Fixed 7/4/2023 by grinding the spindle nose lip. The three jaw chuck can now be installed and removed by hand with no hammering. A test bar in it now has only 2 thou runout (TIR) at the chuck.<br />
: <s>The three jaw chuck and the faceplate aren't seating properly on the spindle nose. Its too tight on the register diameter of the lip. This results in grossly excessive runout, and also makes this chuck and the faceplate a PITA to fit or remove.</s><br />
: ''The spindle nose had been abused with a hammer (before my time) which mushroomed it and may have brinelled its bearings. See '''Excessive Runout''' and '''Spindle bearings''' above.''<br />
<br />
== Manuals, Books and other resources ==<br />
=== Manuals ===<br />
The [https://wiki.richmondmakerlabs.uk/images/a/a3/Lathe_InductionNotes.pdf RML CJ18A Mini-Lathe Induction Notes]. Your mandatory Lathe Induction will cover most of this but its good to be able to refer back to it. Also see [[:File:Lathe Induction Bushing.pdf|Lathe Induction Bushing]], which you will make during your induction, to introduce the four key lathe skills: facing, turning, drilling, and parting off. <br />
<br />
Official [https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Amadeal CJ18A Manual], or paper copy (less complete) kept on shelf above lathe.<br />
<br />
The [https://www.chesterhobbystore.com/wp-content/uploads/2022/11/Conquest-Super-Lathe.pdf Conquest Super Lathe manual] is considerably better than the Amadeal manual and is for a near-identical machine.<br />
<br />
The [https://littlemachineshop.com/images/gallery/info/minilatheusersguide.pdf Mini Lathe User’s Guide] from LittleMachineShop.com is even more comprehensive, going into its usage in some detail, with a proper TOC, and covers both US and Metric versions of Realbull Mini-lathes. ''The only fly in the ointment is the threading section assumes a US lead screw so change gear selections and threading dial divisions will not be correct for our lathe.''<br />
<br />
[https://www.arceurotrade.co.uk/machineguides/C3-Mini-Lathe-Dismantling-and-Reassembly-Guide.pdf Sieg C3 Mini-lathe Dismantling and Reassembly Guide] "A picture story book to help you dismantle and reassemble your Sieg C3 Mini-Lathe" ''It is similar enough to ours to serve as a maintenance guide, except for the electronics, spindle drive and other headstock innards.<br />
<br />
The motor controller is a clone of a [https://acim.nidec.com/drives/kbelectronics/-/media/kbelectronics/documents/dc-drives/manuals/kbic_manual.ashx?la=en KBIC® SCR DC Motor Speed Control]<br />
<br />
=== Books ===<br />
'''Metal Turning on the Lathe''', by David A Clark, Crowood Metalworking Guides, ISBN-13: 978-1847975232 [https://www.amazon.co.uk/gp/product/B00E78RKIG Kindle Edition (£8.99)]. ''A 'free' epub can be googled for, *NOT* linked here due to dubious legality.''<br />
<br />
'''[https://archive.org/details/03screwcuttinginthelathe Screwcutting In The Lathe]''', by Martin Cleeve (a pen-name of Kenneth C Hart), Workshop Practice series #3, ISBN-13: 9780852428382<br />
<br />
'''[https://archive.org/details/15workholdinginthelathe Workholding in the Lathe]''', by 'Tubal Cain' (a pen-name of Tom Walsh), Workshop Practice series #15, Argus Books, ISBN-10: 0852429088<br />
<br />
'''[https://archive.org/details/20metalworkandmachininghintsandtips Metalwork and Machining Hints and Tips]''', by Ian Bradley, Workshop Practice series #20, ISBN-13: 9780852429471<br />
<br />
'''[https://archive.org/details/38toolandcuttersharpening Tool and Cutter Sharpening]''', by Harold Hall, Workshop Practice series #38, ISBN-13: 9781854862419<br />
<br />
'''[https://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpaperT204.pdf Cutting Fluids]''', by EC Bingham, NIST Tech. Paper No. 204, 1921<br />
<br />
=== WWW resources ===<br />
==== Mini-lathe Specific ====<br />
There's a *LOT* of mini-lathe info online. Notable sites include:<br />
* http://www.mini-lathe.com/ - A major Realbull/Sieg mini-lathe resource.<br />
* http://mikesworkshop.weebly.com/lathe-modifications.html - many mods including carriage DRO autostop, and variable speed leadscrew motor drive, cross-slide motor drive, etc. He also has a page with a bunch of accessories, toolholders etc. - http://mikesworkshop.weebly.com/lathe-accessories-and-tooling.html<br />
* http://andysmachines.weebly.com/variable-speed-controls.html - Scroll down to the 'UPDATE' section for the schematic of a very similar SCR speed control board. It also has the schematic for an earlier version of the Auxiliary Control Board (aka: 'Filter' board).<br />
* https://www.youtube.com/watch?v=WbJM9ooveo8 - A video tour of a very very similar mini-lathe. Significant differences: ours has a 4" longer bed, a quick change toolpost, a different tailstock, no DRO (apart from basic spindle speed, so skip 16:12 to 28:50 in the video), larger chucks and a carriage lock.<br />
<br />
==== Forums ====<br />
''with publicly accessible archives''<br />
* https://groups.io/g/7x12MiniLathe - Mini-lathe specific, active<br />
* https://www.hobby-machinist.com/forums/mini-lathe-mini-mill-information.220/ - active<br />
==== Youtube Playlists & Videos ====<br />
* Blondihacks: [https://www.youtube.com/playlist?list=PLY67-4BrEae9Ad91LPRIhcLJM9fO-HJyN Lathe Skills] (playlist) - "This is an educational series to help you learn to use your metal lathe. Watch them in order for best results! Satisfaction not guaranteed, especially if you're a cranky sort of person."<br />
* Frank Hoose (Minilathe.com) has a couple of relevant Youtube playlists:<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn7ON0jGM5UbM-KZDT56MOIp Mini Lathe Operations]<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn4nGRZaVq3wTOlvZNOmdAZ2 Mini Lathe Overview]<br />
<br />
==== General Machining ====<br />
* https://www.machiningdoctor.com/ - "THE #1 MACHINING TECHNICAL HUB"<br />
<br />
==Projects==<br />
[[File:VESA mount.jpg|thumb|Machined VESA mounting plate (left) and plate from Dell monitor stand it must match (right). The translucent washer shows the size of the original center hole.]]<br />
* My first faceplate project was boring out the center hole in a VESA mounting plate to adapt it to fit onto a surplus Dell 1708FP monitor stand. The part was centered using the tailstock dead center engaging with its original center hole. I clamped the part with studs and penny washers on the driving side of two opposite corners, with cap screws in the next slot round to trap the corners under the clamping washers, then withdrew the tailstock and dead center. After machining out the bore, I used the tip of the tool, rotating the chuck by hand, to scribe a circle for laying out the bolt holes. I finished off laying out and drilling the bolt and locating holes by hand at home, fitted it to the stand, and mounted the 2nd hand LG 24" widescreen monitor.<br />
<br />
* Another ultimately unsuccessful project was fly cutting aluminum flat bar to thickness to make custom shims for the set of carbide insert tools, for the four way toolpost. The 8 mm shank tools need ~2.5 mm shim stacks, and the 6 mm shank tools need ~4.5 mm shim stacks. Ideally I'd machine single shims, but the only stock I've got handy cleans up to only 3.2mm, and some fine shimming may be needed to fine-tune the tool height.<br />
<br />
: After sorting out the clamps so they were no longer twisting the aluminum flat bar stock, and switching to the short 45° turning SCMT06204 insert tool in the four way toolpost, to improve rigidity and get a well controlled tip radius, the finish was much improved. I'm still having problems getting an even thickness and am getting approx. 0.05mm variation, I suspect due to the aluminium bar stock distorting due to internal stresses as its surface is cut away. ''ToDo: try supergluing the stock to the faceplate before clamping to further reduce chatter and stop the warping.''<br />
: Looking back on this project a year later, its fairly obvious that the thickness variation was probably due to faceplate surface runout due to the damaged spindle nose.<br />
<br />
* Raphael has been working on a steel rocket nozzle with some assistance from myself. We have set up the rough cut chunk of ~ 50mm steel bar, faced both ends (to 50mm length) and turned the OD to 49mm to clean it up. Its going to need through drilling, probably some boring, and quite a bit of detail work on the OD. It will then need to be transferred to a jig in the drill press vice to allow a pattern of angled traverse holes to be drilled with acceptable accuracy.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_Lathe_Notes&diff=17681Ian M's Lathe Notes2024-03-14T15:21:49Z<p>IanM: /* Cleaning and Maintenance */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br />
<br />
''Currently these notes are semi-organized and non-authoritative. As I become more experienced with the RML CJ18A mini-lathe, I'm cleaning up, extending and reorganising them. Some lathe operating experience is assumed. If in doubt, '''*ASK*''' me, Andy H<sup>*</sup> , Jonathan H or another experienced minilathe operator!<br />
<br />
''* Andy H should be asked (for an authoritative answer) any questions involving RML usage policies or acquiring tooling or materials through RML.''<br />
<br />
== The Lathe ==<br />
Our Facilities page [[Facilities#Lathe|has]]:<br />
<blockquote><br />
'''Lathe'''<br />
[[File: Lathe2.jpg |200px|right | Lathe]]<br />
In the kitchen. <br />
<br />
Marked as a CJ18A Mini-Lathe from [[https://www.amadeal.co.uk/acatalog/CJ18A-Mini-Lathe-7x14-Machine-100mm-3jaw-Metric-With-Metal-Gears-AMA_LA_CJ18_M_3_MGRB.html Amadeal]]<br />
[[https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Manual]] <br />
<br />
[[Media:Lathe InductionNotes.pdf| Induction Document]]<br />
<br />
Possible upgrades:<br />
*https://www.youtube.com/watch?v=GwT-JQLbNPA<br />
<br />
''Please do not use the lathe until you have received induction'' <br />
<br clear=all><br />
</blockquote><br />
Its a Chinese import 7x14 mini-lathe. The 7x14 refers to the maximum diameter and length of work, in inches and is only a theoretical measure of the working envelope as you loose length to the chuck + any tailstock tooling, and the diameter is over the bed, not the cross-slide. See actual specifications below. <br />
<br />
Most if not all Chinese 7x10 to 7x16 mini-lathes seem to be remarkably similar (not uncommon with Chinese products due to [https://www.bunniestudios.com/blog/?p=284 Shanzhai (山寨)] )<br />
and the OEM of our Amadeal CJ18A Mini-Lathe was probably [https://www.made-in-china.com/showroom/cheap-lathe Yangzhou Realbull Machinery Co. Ltd]. Very similar lathes are also made by [https://www.siegind.com/lathe-machine.html Sieg], but their lathes tend to be slightly less sophisticated than the equivalent Realbull models.<br />
<br />
''N.B. Many Sieg parts are known to have slight but critical differences from Realbull parts, so '''DON'T''' order Sieg spares for a Realbull lathe!<br />
<br />
== Key Specifications ==<br />
Amadeal says the CJ18A Mini-Lathe is a 7x14 model with:<br />
<blockquote><br />
* Power 550 W<br />
* Distance between centres : 350 mm<br />
* Swing Over Bed: 180 mm<br />
* Swing Over Cross Slide: 110 mm<br />
* Taper: MT3<br />
* Tailstock Taper: MT2<br />
* Chuck diameter: 100 mm<br />
* Spindle Speed: 50 - 2500 rpm ''(with digital readout)''<br />
* Spindle Bore: 20 mm<br />
* Cross slide Travel: 65 mm<br />
* Range of Metric Threads: 0.5 - 2.5mm.<br />
</blockquote><br />
* The lead screw is metric, pitch 1.5 mm.<br />
* The spindle center is 90.6 mm above the flat of the bed (measured).<br />
<br />
Even though the compound and cross slide handwheels appear to be calibrated in thousandths of an inch, as ours is a metric machine, they only approximate that. One turn of a slide handwheel is 1mm advance, and they have 40 divisions, so each division is 0.025 mm, (approx. 0.984 [https://en.wikipedia.org/wiki/Thousandth_of_an_inch thou]). Similarly, the tailstock quill advances 1.25 mm per handwheel turn, which has 50 division dial, giving the same 0.025 mm divisions, but only 4 turns per 5 mm. The carriage handwheel is awkward - it moves approx. 19.2 mm per turn, and doesn't have a dial scale.<br />
<br />
== Notable Accessories ==<br />
We have:<br />
* [https://www.amadeal.co.uk/acatalog/160mm-Face-Plate-for-the-4-Mini-lathe-AMA_AC_CJ18A_FP160RB.html#SID=129 160 mm (6 1/4") Faceplate]<br />
* 100 mm (4") three jaw self-centering chuck (OEM standard) 22.5mm bore, with inside and outside jaw sets<br />
* 100 mm (4") four jaw (independent) chuck with reversible jaws (8 TPI screws)<br />
* Tailstock drill chuck (max. 13 mm dia.)<br />
* Live center for tailstock (+ OEM fixed center) <br />
* Four way Tool Post (OEM Standard)<br />
* [https://www.amadeal.co.uk/acatalog/Quick_Change_Tool_Post_for_the_mini-lathe.html Quick Change Tool Post] + 3 tool holders<br />
* [https://www.amadeal.co.uk/acatalog/Fixed-Steady-for-Mini-Lathes-AMA_AC_CJ18A_FSRB.html#SID=145 Fixed Steady Rest]<br />
* [https://www.amadeal.co.uk/acatalog/Travelling-Rest-for-Mini-Lathes-AMA_AC_CJ18_TSRB.html#SID=144 Travelling Steady Rest]<br />
<br />
''You'll find all of the above on the shelf above the lathe, with the accessories in the wooden box, apart from the steadies, which live next to it. Change gears, spare parts, and most cutting tool tips/blanks are in labelled white rectangular tins behind the lathe.''<br />
=== Measuring Tools ===<br />
We have:<br />
* Various dial indicators - the one with the adjustable magnetic base stand is the most convenient for most lathe setup work.<br />
* 25mm micrometer (in little grey case)<br />
* Grey case containing set of measurement tools including dial calipers, micrometer, steel rule (metric & inch), engineers square, and a fish-tail gauge<br />
<br />
''We currently lack''<br />
* ''A tool height setting gauge''<br />
<br />
=== Hand Tools ===<br />
Some common tools needed for normal use are kept with the lathe, in or attached to the wooden accessories box:<br />
* 2 mm Allen key - adjusting cross-slide and compound gibs<br />
* 4 mm Allen key - quick change toolholder tool clamping screws + height adjust, tightening dials<br />
* 5 mm Allen key - four way toolpost tool clamping screws, engaging/disengaging threading indicator<br />
* 6 mm Allen key - locking/unlocking quick change toolholder<br />
* 8 mm spanner - locking carriage when 8 mm socket can't be used, locking gib adjuster nuts <br />
* 13 mm spanner - changing chucks, locking steady rest jaws<br />
* Very long needle nose pliers - for grabbing swarf safely, holding one end of emery cloth safely so you can keep your fingers away from the jaws, and extricating small objects from awkward places.<br />
<br />
== Change Gears ==<br />
[[File:BC puller 1.jpg|thumb|Custom puller for B-C stub shaft]] [[File:BC puller 2.jpg|thumb|Pulling the B-C stub shaft]]<br />
See "Conquest Super Lathe" manual ([[#Manuals|below]]), section '''4.7 Change Gears''', PDF pages 28-29, but see below for mesh adjustment. The LittleMachineShop.com "Mini Lathe User’s Guide" (also below) section '''Threading''' gives a far better explanation, with pictures and diagrams, but its for a lathe with a US 1/16 inch pitch leadscrew, not a metric 1.5 mm pitch one like ours, so you *MUST* ignore all the tables in that section, replacing them with metric mini-lathe (with 1.5 mm pitch leadscrew) equivalents. <br />
<br />
We have the following tooth count gears: 20,20, 30, 35, 40,40, 45, 50,50, 60,60, 80,80<br />
which consist of the OEM power feed gears + the metric change gear set. Apart from the metal 20 tooth pinions, they are all plastic, probably Delrin if the molded in 'POM' marking can be trusted, but possibly plain Nylon 6, and are metric Module 1.<br />
<br />
If we wanted to add the capability to cut US/Imperial threads we'd need to buy additional 55, 57 and 65 tooth gears, and possibly a 21 tooth metal pinion.<br />
<br />
CGTK's [https://www.cgtk.co.uk/metalwork/calculators/changegears/minilathe?gears1=20,20,30,35,40,40,45&gears2=50,50,60,60,80,80&gears3= Change Gear Calculator] ''(link preloaded with our gear list)'' is useful if you don't want to calculate the ratios from first principles. Not all suggested combos will physically fit.<br />
<br />
* Take care *NOT* to loose the keys in the A and D shaft keyways - turn each shaft till the keyway is up before removing the gear. <br />
* The B and C gears are coupled by a hollow stub shaft (with an integral key), which is so tight in the gears it has to be pressed or driven out - I've made a puller just for this task, kept in the change gears tin.<br />
* The center of the B-C stub shaft *MUST* be lubricated where it runs on its pin on the change gear banjo bracket, with grease or heavy oil. ''Seizure of the stub shaft due to running dry is a frequent cause of catastrophic mini-lathe geartrain failures!''<br />
* Don't get oil on the change gears as it can cause plastic gears to crack. Only PTFE drylube or plastic compatible white grease should be used on their teeth. <br />
* Adjust the B-C pin position in the straight slot first to set the C to D gear mesh, tighten its nut, then swing the whole banjo about the D shaft boss to set the A to B mesh, and finally tighten the banjo clamping nut.<br />
* Check both gear meshes have running clearance by turning the chuck by hand enough to complete one full turn of the leadscrew, and by attempting to turn the intermediate gear(s) to assess backlash, If excessive resistance is felt or if there's significant backlash, readjust the gears. If you have difficulty judging the mesh, a strip of 80 gsm copier paper (approx. 0.1 mm thick) wound into the meshing teeth before tightening the stud or banjo will give appropriate clearance once removed. Once setup, check the gears run quietly under power.<br />
* If the sum of the tooth counts C+D is the same as for the ones you just removed and they were correctly meshed, you don't need to move the stub shaft pin. If A+B is <u>also</u> the same, you don't need to move the banjo. e.g. If it was set up for 16:1 reduction power feed, 1 mm (40:60 - 50:50) for M6 and 1.5 mm (e.g. 40:60:40) for M10 pitches can thus be achieved by only swapping gears. <br />
<br />
''The change gears, puller, etc. and a box spanner for the banjo nut are kept in a white rectangular tin behind the lathe.''<br />
<br />
=== Power Feed ===<br />
When used for turning with power feed, the change gears should be set for a 16:1 reduction (A:20 : B:80 - C:20 : D:80) using the pair of small metal 20 tooth pinions and the 80 tooth plastic gears (largest in set), for a feed of 0.09375 mm per turn (1.5 mm/16). Unless continuing your threading project the next session, please re-fit the 16:1 power feed set after threading so the power feed is ready for use. <br />
<br />
* *ALWAYS* leave the feed direction selector lever in its neutral (no feed) position, and the half-nuts open after use.<br />
* *ALWAYS* check the carriage lock is disengaged before engaging power feed. Unlock the carriage after use. <br />
<br />
=== Threading Dial ===<br />
The threading dial is an aid to re-engaging the half-nuts at the right moment so the tool will retrace its previous path cutting deeper, rather than offsetting axially some fraction of the thread pitch and ruining your work. Its based on the concept of the lowest integer multiples of the leadscrew and thread ''(being cut)'' pitches that exactly match, but for mechanical simplicity it only covers certain selected multiples of the leadscrew pitch.<br />
<br />
We have a choice of three pinion gears:<br />
{| class=wikitable<br />
|+ Threading dial Pinion Gears<br />
|-<br />
! Teeth !! Colour Dot !! Usable lines !! OD gear !! Dist. per turn<br />
|-<br />
| 14 || Red || 1,7 || 7.51 mm || 21 mm<br />
|-<br />
| 15 || Orange || 1,5,9 || 8.05 mm || 22.5 mm<br />
|-<br />
| 16 || Green || 1,4,7,10 || 8.37 mm || 24 mm (2 mm/div)<br />
|}<br />
They are now colour coded, with a paint dot on the gear end face ''(the only non-wear surface)''. The 16 tooth one is normally left on the lathe, but disengaged when not threading to minimise wear on the lead screw. The others are kept in the Change Gear tin.<br />
<br />
There's a threading dial 'pickup' calculator here: https://www.cgtk.co.uk/metalwork/calculators/threaddialindicator <br />
<br />
Initially select ''Lathe:'' '''Custom''', and enter the following below:<br />
* ''Units:'' '''Metric'''<br />
* ''Lead Screw Pitch (mm):'' '''1.5'''<br />
* ''Thread Dial Indicator Gear Teeth:'' '''16,15,14''' <br />
* ''Lines on Thread Dial Indicator:'' '''12''' <br />
* ''Line Marking:'' '''Every Line Numbered'''<br />
Note the teeth list is entered in reverse order so the resulting table highlights any required pinion changes.<br />
<br />
N.B. The dial is only friction clamped to the pinion by its center screw. If you have any reason to suspect it may not be properly aligned: <br />
# With the power off and the carriage unlocked, engage the feed direction lever upwards. You'll probably need to turn the chuck by hand to get it to engage.<br />
# If the threading indicator isn't already engaged, loosen the threading dial support block bolt, pivot the block to engage the pinion with the leadscrew and retighten the bolt.<br />
# Engage the half nuts, again turning the chuck by hand till they drop in. <br />
# Turn the chuck a couple of turns, top towards you to take up any backlash, then lock the carriage, taking care not to push it left while locking it.<br />
# Loosen the screw securing the dial to the pinion.<br />
# Align the '1' line of the dial with the index line, by rotating the dial clockwise, then retighten the screw.<br />
# Don't forget to disengage half-nuts and unlock the carriage!<br />
<br />
The above instructions should result in the half-nuts engaging cleanly when exactly on any valid line when threading towards the headstock. If it is required to thread away from the headstock, there will be a slight offset from the line due to backlash between the spindle gear and leadscrew, so engage slightly early.<br />
<br />
Changing the pinion:<br />
# Loosen the threading dial support block bolt and disengage from the leadscrew.<br />
# Undo dial center screw, and remove it and the dial, dropping the old pinion out the bottom.<br />
# Oil the shaft of the new pinion with a drop of light oil and insert it from below, gear end down.<br />
# Refit dial and screw.<br />
# Check the dial and pinion turn freely with minimal resistance.<br />
# Align as above.<br />
<br />
== Tailstock and Steadies ==<br />
These are mostly used to support long work ''(long with respect to its diameter)'' to improve rigidity, increasing accuracy and reducing chatter. The Tailstock quill is also used with a drill chuck for drilling.<br />
=== Tailstock ===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock base]]<br />
The tailstock can be offset to turn shallow tapers between centers. We don't currently have the accessories to turn between centers, namely <s>a MT3 dead center for the spindle, or</s> any drive dogs for the work. Also realigning the tailstock after turning a taper can be a PITA. The photo shows the tailstock adjusting screw locations ''(C - Lateral, and D - Skew)'' and the block on the baseplate they engage with. Adjustments can only take effect when the tailstock locking lever is eased to take the pressure off the baseplate. As we don't have a MT3 center, one has to turn a fresh point on a test workpiece for a rough tailstock alignment reference. Fine alignment, to avoid inadvertent taper turning, can be done by mounting a long precision ground bar between the chuck (or preferably a center in the spindle), and a dead center in the tailstock and sweeping it with a dial indicator on the carriage. Finally a test cut should be taken at either end of a bar between centers, and the diameters checked with a micrometer. Assuming the bed has previously been properly levelled and shimmed to take out twist ''(not the case at RML as we don't have it bolted down)'', any remaining difference in diameter will be double the tailstock offset, smaller at the tailstock being offset towards the front. Fine adjustment cant be achieved by jacking with the screws, its best to ease the adjusting screws, bump the tailstock into alignment then take up the screws again, checking the alignment is maintained when the tailstock is unlocked and relocked. There is no vertical adjustment, though shims can be added between the tailstock and its base.<br />
<br />
==== Tailstock Quill ====<br />
There is a metric/imperial scale on the top of the quill, read against the end of the tailstock, for depth measurement when drilling. The tailstock quill has a 1.25 mm pitch thread and a 50 division dial. Each division is therefore 0.025 mm, and it only takes 4 full turns of the handwheel to move the quill 5 mm. <br />
<br />
To eject MT2 taper tooling and centers from the tailstock, wind the quill all the way in.<br />
<br />
N.B. The quill anti-rotation pin (dog-tip setscrew + locking nut in top of tailstock near to the quill lock) is only M5. It will sheer if a large diameter drill jams in the work. Please back it out clear of its keyway if using large drills, and use alternative methods of preventing chuck rotation. To re-engage it, crank the quill out till you can see the keyway, align it with the screw and screw in the screw till it gently bottoms out, then back it off a quarter turn. Try twisting the quill to check its properly engaged, then tighten the locking nut gently to hold the screw in position clear of the bottom of the keyway.<br />
<br />
=== Steady Rests ===<br />
We have two, both with brass tips that must be kept lubricated during use.<br />
<br />
The fixed steady mounts on the ways, and is most useful when turning longer work that wont fit through the spindle bore. Adjustment is critical, and the surface the tips run on must be smooth and concentric, as any misalignment that forces the work off center will result in the work wobbling in the chuck, marring it, with a high risk of it becoming un-chucked, which can be dangerous at speed.<br />
<br />
The travelling steady mounts to the headstock side of the carriage to locally resist the deflection of thin long work, due to the cutting forces. It only has two tips, to resist climb, and deflection away from the tool, and requires readjustment after every cutting pass.<br />
<br />
== Tooling and Tool Holders ==<br />
'''Key dimensional data:'''<br />
* The quick change holders accept up to 10 mm shank tools. <br />
* The four way toolpost has 50 mm long sides, a seat width of 15 mm and can clamp tools of up to 5/8" (15.875 mm) shank ''(check this)'', but the slot base is only 10.4 mm below the spindle center so cannot be used with >10 mm shank tooling unless it has a dropped tip. Large tooling with a centered tip is also problematic as you run out of height above the shank when trying to shim to match the spindle center height. <br />
<br />
===Quick Change Toolpost===<br />
I've got the quick change toolpost and toolholders setup for mostly easy use. The three toolholders came with cantilever height setting arms which historically haven't been installed as the supplied fixing screws were too short. That's all now sorted out and a HSS RH turning tool and a HSS hand-ground grooving/parting-off tool are now mounted in two of the holders and set to height. The third is kept free for other tools. <br />
<br />
The quick change toolpost has been modified with a spring to press the dovetail clamp outwards and help stop it twisting or flopping about to ease toolholder fitting and removal. The dovetail clamp (socket headed screw on toolpost side opposite dovetail) feels a bit stiffer than before, but will take less than half a turn to go from open (with the toolholder lifting out or dropping in easily) to fully clamped. As there is so much less clearance in the open position you should no longer need to wiggle the toolholder while clamping it to get a consistent height. If the dovetail clamp ever gets misaligned, twist it straight by eye, slacken off a bit further than usual to get a toolholder on, clamp it to align the dovetail then release, reseat the toolholder and re-clamp to ensure its at its preset height. You cant adjust the height by 'jacking' with the height screw due to its offset leverage. Instead, back off the height screw and hold the toolholder at the desired height while locking the dovetail clamp, then adjust the height screw (and locking nut) to hold it there, then check it doesnt change height significantly when you unclamp and reclamp the dovetail. <br />
<br />
Unfortunately the OEM height setting screws foul the toolpost locking nut handle. Currently, if you need to swap toolposts you will have to first remove the quick-change tool holder from the post. There is enough nut handle swing to allow the quick change toolpost to be unclamped and rotated to fine set the tool angle without removing the toolholder. It also seems the mating surfaces may be slightly out of square, as if you rotate the toolpost 90° or 180°, the nut swing may be insufficient to re-clamp it without removing the toolholder to do so. Add a M10 washer under the locking nut if the handle ends up pointing in an undesirable direction! A thin M10 washer is kept with the toolpost collar for this purpose, and will shift the handle position by about a third of a turn. <br />
<br />
''ToDo: Make a taller nut of a similar pattern, to clear the height setting screws.''<br />
<br />
===Four Way Toolpost===<br />
The OEM four way toolpost is significantly more rigid than the quick change toolpost + holders because it has fewer and thicker parts and less overhang. Therefore the four way toolpost should be used when using carbide tooling. It requires shimming under the tool to set the tip height to the spindle center height - see below. The tool shanks are mostly significantly less than 15 mm wide, so need to be centered under its clamping screws, tempting as it is push the shank in for full side contact with the toolpost. If possible clamp the shank with all three screws not just two.<br />
<br />
==== Shimming ====<br />
We typically only mount up to two tools, and want maximum rigidity, so use 50 mm x 15 mm shims, (the full seat area), preferably with deburred edges and radiused corners so they aren't a hazard to the operator.<br />
<br />
We have pre-cut and marked shims of the following thicknesses: <br />
* 1x 3.23 mm, 2.42 mm, 1.56 mm, 0.32 mm, and 0.25 mm<br />
* 2x 1.00 mm, 0.77 mm, 0.12 mm, 0.11 mm, 0.10 mm and 0.05 mm<br />
* 4x 0.53 mm<br />
<br />
Our shims are mostly found materials (hence the awkward thicknesses) and are mostly a mixture of aluminium and steel, with a couple of GRP ones. The toolpost seat '''<u>must be absolutely clean</u>''' to avoid embedding debris in the aluminium or GRP shims, to get a consistent height and avoid tilting the tool - wipe it every time you change a tool! Put the thin shims at the bottom of the stack to avoid the tool shank edges creasing them. Shims are kept in a little yellow plastic box with a clear lid, near the carbide tools case.<br />
<br />
I made a tool height setting gauge (T shaped black acrylic with steps in its sides) which can be used to check the tool tip height matches the spindle center height using either the flat of the ways or the saddle as a reference. The tool tip should just fit under the lip of the appropriate step, with the T arms across the ways flats or on the saddle. It is kept in the box with the carbide insert tools.<br />
<br />
''ToDo:'' <br />
<br />
* ''Cut more shims neatly, mark them with their thickness.''<br />
* <s>''Do test cuts and start noting shim stack-ups for various tools.''</s><br />
* ''Organise shim storage!''<br />
<br />
=== HSS Tools ===<br />
[[File:Tool Bit Geometry.jpeg|thumb|Single point cutting tool geometry]]<br />
Our HSS tools are made from 8 mm square bar stock, hand-ground to tip profile in-house. See LittleMachineShop's [https://littlemachineshop.com/images/gallery/instructions/grindingtoolbits.pdf Grinding Tool Bits] notes. <br />
<br />
I've installed our usual HSS LH turning and parting off tools in two of the quick change holders and set the heights correctly. There are a couple of other HSS tools or tool blanks knocking about. Taking heavy cuts turning steel (even with good cutting oil) blunts HSS tools fairly quickly, which are time-consuming to re-sharpen nicely without a dedicated tool & cutter grinder with appropriate jigs. Its worth noting that the usual 'speeds & feeds' tables are commonly based on surface speeds expected to give a half hour (active cutting) tool life before resharpening.<br />
<br />
I touched up the LH turning tool by lapping on wet & dry (silicon carbide) paper on glass (Aka: [https://en.wikipedia.org/wiki/Scary_sharp 'Scary Sharp']) working upwards through the grits 200, 400, 600 and finally 1000, initially 'bluing' the surfaces to be lapped with a marker pen to see which areas needed taking down more. The end of the tool was significantly uneven so I touched that up freehand on the bench grinder to flatten it when it became apparent that 200 grit lapping wasn't cutting where it needed to. There was an existing micro-bevel on the leading side, which I kept. Finally I 'dubbed' the leading corner vertical edge on the 1000 grit to give it a very slight nose radius. A test cut on brass gave a very nice finish when turning.<br />
<br />
''Ian B has purchased some spare 8mm HSS tool blanks - talk to a lathe trainer if your proposed lathe work needs custom ground HSS tooling.'''<br />
<br />
=== Brazed Tungsten Carbide Tools ===<br />
Somewhat of a half-way house between hand ground HSS tooling and insert tooling with the disadvantages of both and some more besides - e.g. they are much harder to sharpen. So why do we bother? Some tool geometries would be awkward and tedious to hand grind, and Chinese import brazed carbide tooling is about half the price of similar HSS tooling, and far more readily available. Also, for space constrained tooling like boring bars, if you want carbide, for insert tooling, the size of the insert and its clamping seriously limits the minimum hole diameter you can work in. I have purchased a set of 3/8" shank brazed carbide tipped boring bars, but we currently cant sharpen them, due to lack of a diamond grinding wheel. <br />
<br />
=== Tungsten Carbide Insert Tools===<br />
Decoding ISO insert tooling part numbers: https://www.cutwel.co.uk/blog/learn-the-turning-tool-iso-code-system<br />
[[File:Carbide set.jpg|800px|thumb|left|Our set of Tungsten carbide insert lathe tools (before the new inserts were fitted)]]<br />
<br />
{| class=wikitable<br />
|+ Tools, left to right, (+ last across top):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| SSKCR0610H06 || 75° through boring || SCMT06204 || Long || 6 || 6.34 || ''4.33''<br />
|-<br />
| SSSCR0610H06 || 45° deep facing, internal chamfering || SCMT06204 || Long || 6 || 6.13 || ''4.58''<br />
|-<br />
| SWUCR0610H05 || 93° boring, deep facing || WCMT050308 || Long || 6 || 6.22 || ''4.48''<br />
|-<br />
| SWGCR0810E05 || 90° RH turning & facing || WCMT050308 || Short || 8 || 8.25 || '''2.45'''<br />
|-<br />
| SSSCR0610E06 || 45° turning, chamfering || SCMT06204 || Short || 8 || 8.75 || ''1.93''<br />
|-<br />
| SSBCR0610E06 || 75° RH turning, chamfering || SCMT06204 || Short || 8 || 8.72 || ''1.98''<br />
|-<br />
| LW0810R-04 || 60° external threading || JCL15-120 || Short || 8 || 7.44 * || ''3.28''<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || 8.23 || ''2.5 ?''<br />
|-<br />
| LN0813R-04 || 60° internal threading || JCL15-120 || Long || 7.95 || 7.44 * || ''3.28''<br />
|}<br />
<br />
{| class=wikitable<br />
|+ More Tools, (loose in tin):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || ~8.5 (not in use) ||<br />
|-<br />
| [https://www.glanze.co.uk/product/glanze-12-mm-60-degree-metric-internal-threading-tool/ Glanse SIR0012K11] || 60° internal threading bar || 11IRA60 || Long || 12 dia || ??? || ???<br />
|}<br />
''Shim stack heights in bold are tested, in italic are only calculated.'' ''Tip heights marked * are with new JCL15-120I inserts. The single remaining plain JCL15-120 insert has a slightly higher tip height.''<br />
<br />
Carbide tooling typically requires two to three times more speed than HSS and at least a couple of 'thou' depth of cut for best results.<br />
<br />
Chatter can rapidly kill carbide tooling by chipping the cutting edge. To improve rigidity and reduce the risk of chatter, the cross-slide and compound gib screws need to be well adjusted so there is minimal play in the slides, tool stick-out should be minimised, the four way toolpost should be kept over the cross-slide, and the work should be kept close to the chuck (or otherwise supported by tailstock or steady rest) to avoid excessive deflection.<br />
<br />
Thermal shock is almost instant death to carbide, and when dry cutting the insert tip can run very hot, so do not add extra cutting fluid manually during the cut. Pre-apply what you need, evenly, before starting the cut.<br />
<br />
Parting off or facing to center is high risk - if the tool tip is even slightly below center or if tool or work deflection takes it below center, the work will tend to climb over the tool tip as the cut approaches center, breaking the insert. To avoid this, the tool should be shimmed slightly above center, sufficient to allow for work and tool deflection, and unless very close to the chuck, a steady should be used. Its often preferable to part to a couple of mm dia. remaining then stop and saw through the remainder, then clean up by facing. Parting off hollow parts is much lower risk.<br />
<br />
Further investigation of the Tungsten carbide insert tool height situation is not encouraging - the so-called 'set' in question does not have a consistent tip height ''(see above table)''! In a real set, the insert seats *should* be machined allowing for the insert thickness to bring all the cutting edges to the same height with respect to the shank underside. However if you place them tip to tip on a table its easy to see there is considerable height variation, so they need to be individually shimmed (or at best, one machined shim will only be right for two or three tools). At this time we don't have dedicated shim stacks for each tool.<br />
<br />
A 2.42 mm thick shim brings the SWGCR0810E05 90° RH turning & facing tool almost exactly to center height, and good results were obtained turning 1" steel pipe. However facing 50mm steel bar stock to center found it to be slightly low, leaving a fractionally under 0.05 mm 'pip' so it needs another 0.03 mm to bring it fractionally above center. Fractionally too high is generally preferable to fractionally too low, due to tool deflection, so adding an 0.05 mm shim to the stack should produce optimum results.<br />
<br />
==== Inserts ====<br />
Ian B has purchased the spare inserts we needed in sets of five. He even was able to get the CK3 parting-off inserts which had been difficult to source!<br />
<br />
Inserts used in above tool set:<br />
* 3x SCMT06204 (square, indexable) https://www.rdgtools.co.uk/acatalog/SCMT-06-Carbide-Insert.html<br />
* 2x WCMT050308 (triangular, indexable) https://www.rdgtools.co.uk/acatalog/WCMT-05-T3-08-5XTIP-8813.html<br />
* 2x JCL15-120 (60 deg threading point) https://www.rdgtools.co.uk/acatalog/X5-JCL-15-120L-THREADING-TIPS-60-DEGREE--X5-TIP---23455.html<br />
* CK3 (parting off) https://www.rdgtools.co.uk/acatalog/CK3-CARBIDE-TIPS---PARTING--BOX-OF-5PCS--9437.html<br />
<br />
Inserts used in other tools:<br />
* 1x CK3 (as above) also missing from spare parting off tool<br />
* 1x 11IRA60 in Glanse threading bar + 1x spare<br />
<br />
=== Drills ===<br />
Various sizes of center drills are kept in a plastic bag next to the wooden accessories tray. There's also a small box of 2.5 mm center drills.<br />
<br />
We have a set of 11 TiN coated HSS drill bits from 1.5 to 8 mm, (in a cylindrical plastic index box) for tailstock drilling of brass, aluminium and non-abrasive plastics. To keep them sharp enough for the precision work we expect from the lathe, please don't use them for steel or reinforced plastics, and don't borrow them for non-lathe use. Metric and US [https://littlemachineshop.com/reference/numberdrillsize.php numbered]/[https://littlemachineshop.com/reference/letterdrillsize.php lettered] general use HSS drill bits are kept in two red metal index boxes next to the drill press.<br />
<br />
== Using the Lathe ==<br />
=== General ===<br />
Making dimensioned parts is primarily done by touching off the tool tip on a reference surface (with the lathe stopped, turning the chuck by hand), zeroing the handwheel dial, then manually counting turns and divisions. When backing off the tool its best to do so by exactly one whole turn so you don't forget the previous dial position. Stopping and measuring the work before taking the final cuts is essential if high accuracy is required. ''I've changed out the dial setscrews for flat tip ones with a tiny slug of solder under them so the dials are now friction fit on their shafts. i.e. if you hold the handle firmly taking up the backlash in the direction of cut, you can zero the dial just by grabbing and twisting it.''<br />
<br />
Carriage movement is less easy to measure as the handwheel is uncalibrated and advances an awkward bit over 19.2 mm per turn. Your options here when shoulders or other features must be exactly positioned are, in order of increasing accuracy: <br />
* Use measuring instruments, scribe the work at the desired length then work to the scribed line. Its often convenient to black the work with a permanent marker, then scribe with the tool tip, turning the chuck by hand.<br />
* for short distances, lock the carriage and use the compound, set parallel to the work<br />
* Set up a long travel dial indicator to measure carriage motion. <br />
N.B. with the leadscrew stopped, and the threading dial engaged, with its default 16 tooth gear, it will make one turn for every 24 mm of carriage movement (2 mm/div). This isn't accurate enough for positioning but is sufficient to check you aren't out by a whole mm or more.<br />
<br />
Do not allow any solvents to contact the chuck guard clear plastic as it will make the plastic brittle, or even craze it, and try to avoid melting it with the work light!<br />
<br />
===Speeds & Feeds===<br />
The surface speed of the tool relative to the work (or visa versa) is important, and best results will be achieved when it is in a tool type and material specific range. Because the surface speed is proportional to the diameter and the spindle RPM, it is usual to vary the spindle speed in inverse proportion to the diameter to get the surface speed in the desired range, and keep it there as the tool tip moves closer to the spindle axis. <br />
<br />
A cutting speed chart for HSS tooling, published by Model Engineer magazine can be found [https://www.model-engineer.co.uk/sites/7/documents/cutting%20speed%20chart.pdf [here<nowiki>]</nowiki>]. The second row is the target feed rate and the rest of the chart, apart from the diameter column is RPM.<br />
<br />
For carbide tooling cutting iron and steels, recommended speeds are generally three times higher than for HSS, but the CJ18A 2500 RPM max. spindle speed (in high gear) means you can only reach the optimum speed range for over 15 mm dia work. For small diameter work, HSS tooling may well be a better choice.<br />
<br />
An online metric speeds calculator is here: https://www.cgtk.co.uk/metalwork/calculators/cuttingspeeds <br />
<br />
How to do the maths to calculate speeds and feeds: https://www.cutwel.co.uk/blog/speeds-feeds-made-easy<br />
<br />
If you can hear the lathe 'sing' as it cuts, you are getting chatter, which invariably results in poor surface finish. Try decreasing (or possibly increasing) the spindle speed till the resonance stops. <br />
<br />
Once you have a wavy surface due to chatter, a light cut wont clean it up as the tool 'twangs' from peak to peak. You have to take a deep enough cut to get under it. For precision parts, its therefore desirable to take a trial finish cut while still 0.5 mm or so oversize, to give an opportunity to tweak the cut to get a good finish, check for taper, and that the part wont be undersize (on your test finish cut nominal diameter).<br />
<br />
=== Slide Locks ===<br />
* The carriage can be locked to the ways using the M5 hex screw through the top of the saddle to the left of the cross-slide. Double check the leadscrew is disengaged and the half-nuts open before locking it. Lock it when facing.<br />
* The cross slide can be locked by a M4 socket headed cap screw just in front of its middle gib screw. Locking the cross slide is helpful when turning very shallow conical features where the cross slide handle is in the way of the compound.<br />
* The compound slide can be locked by a M4 socket headed cap screw in line with the edge of the toolpost mount on the side with the gib adjustment screws. In normal use it should be kept backed off half a turn but it is desirable to tighten it for parting off operations to keep the resulting end faces flat.<br />
<br />
=== Compound ===<br />
The compound consists of a locking swivel and a top slide allowing cuts to be made at an angle to the axis e.g to produce bevelled or tapered features. There is a difference between US and UK usage, in the US a compound angle of 0° means the compound slide is parallel to the cross slide, but in the UK, 0° is parallel to the ways. The compound angle indicator on the CJ18A follows UK practice, 0° parallel to the ways, but it is not to be trusted, its out by a few degrees!<br />
<br />
One of the deficiencies of the CJ18A lathe is the difficulty of setting the compound angle. It is held and locked by two screws hidden under the top half of the compound slide, which must be wound back till its toolpost end is clear of the pivot point to access them. This may have to be repeated several times to snug them up enough to tap it to the desired angle, then finally tighten them. <br />
<br />
We generally keep the compound slide set approximately parallel to the ways so it can be used for short-distance longitudinal positioning without measuring. However it is unlikely to be closely parallel unless a test bar has been swept with a dial indicator on the slide, or test cuts made on a large OD workpiece and checked for taper.<br />
<br />
=== Chucks and Chuck Jaws ===<br />
==== Terminology ====<br />
* Inside jaws have steps on the outside to grip the ID of hollow work, but can also be used as outside jaws on small diameter parts (i.e. that fit through the spindle). <br />
* Outside jaws have steps on the inside to grip the OD of the work.<br />
* Universal chucks have a scroll plate with a spiral screw thread that moves all the jaws.<br />
* Independent chucks have individual adjusting screws for each jaw.<br />
<br />
==== The Chucks ====<br />
* The three jaw universal chuck can only grip near round or hexagonal work, which it centers, but its concentricity is not perfect so e.g. if you reverse the work and continue turning at the same diameter from the other end, you will see a line where the turned surfaces meet. It has separate sets of inside and outside jaws, and we normally keep the inside set installed to use as outside jaws for small diameter work.<br />
<br />
** Our jaws are individually numbered, stamped in the groove. They must be fitted in the correct sequence. The jaw slots are not clearly marked. Lowest runout for small dia. parts is achieved if you fit the jaws with #1 anticlockwise of the makers mark, then continue anticlockwise for #2 and #3.<br />
** A large strong rubber band is a great help getting all the jaws started on the scroll together - with slots #1 and #3 above the centerline and the scroll thread outer tip between #1 and #3, insert jaws #1 and #2 and put the rubber band round them to keep them in their slots. Insert jaw #3 and stretch the rubber band over it to hold it up into its slot. If the scroll was positioned correctly, all jaws should be at the same initial radius. The jaws can now be cranked in with the chuck key and they should all engage in step so they meet in the middle.<br />
:: ''Mini-lathe.com have the best instructions for [https://www.mini-lathe.com/mini_lathe/chucks/chucks.htm#Installing_Chuck_Jaws changing the jaws].'' <br />
<br />
* The four independent jaw chuck can grip most roundish or squarish work, which can either be carefully centered by the user, or deliberately gripped off-center. <br />
** Its jaws are reversible so can be swapped from inside to outside by simply cranking each jaw out and reinserting it the other way round, one at a time. DON'T move the jaws to different slots as they are likely to bind.<br />
** When setting up to face the sides of rectangular objects held crossways, it may be helpful to use both inside and outside jaw orientations, in symmetrical opposing pairs.<br />
** Its screws move their jaw 1/8" (3.125 mm) per turn<br />
<br />
* The jaws must '''never''' protrude from the chuck OD by more than one step, and for safety, its preferable they don't protrude at all, as they make the gap between the front of the bed and the chuck body an even more unforgiving meat grinder, and as the number of teeth engaged with the scroll or screw decreases, they loose strength, just when you need it the most to grip larger/heavier work. <br />
<br />
''Neither chuck is well suited to gripping tapered work safely. When seating work that doesn't quite fit through the chuck bore (which is larger than the 20mm spindle bore limit), be careful that it isn't seating on the chamfered edge of the chuck bore as it is far to easy to get the work slightly cocked so it doesn't run true.''<br />
<br />
==== Changing Chucks ====<br />
* When changing chucks, use the small grey plastic mat to protect the ways under the jaws in case you drop the chuck.<br />
* The spindle nose has two patterns of holes - the three hole pattern is for the three jaw chuck and the faceplate, and the four hole pattern is for the four jaw chuck. One hole is shared between the patterns, and is marked on the spindle nose.<br />
* To fit a chuck:<br />
** First check that the spindle nose and chuck back and recess are free of swarf, grit or other debris. Any foreign objects will tilt the chuck causing excessive runout and may mar the surfaces.<br />
** Remove the nuts and split lock washers from its studs, line its studs up with the hole pattern (preferably with the stud nearest anticlockwise to the makers mark through the marked spindle hole), fit and hold it in place with your right hand, and with your left, get the lock washer and nut on the top stud, and take up the slack.<br />
** One one nut is on, you no longer have to worry about dropping it, and can work round fitting the remaining washers and nuts, taking up the slack on each as you fit it. <br />
** Next, work round again getting them all finger tight, then tighten them gently, and finally work round fully tightening them. <br />
* Removal is the reverse of refitting. Put the washers and nuts back on the chuck's studs so they don't get lost.<br />
<br />
==== Gripping Threaded Work ====<br />
It is generally undesirable to chuck work gripped on a screw thread, as it is difficult to hold the work securely and get good concentricity while avoiding crushing the thread crests. However, if one must, one of the better ways of doing so is to wind a wire helix to fit the thread then clamp on the outside of the wire so it seats on the flanks of the thread. The wire should be mild steel or soft iron for steel parts and copper for aluminium and brass parts, single strand, round and of uniform diameter a little less than the thread pitch. It can be wound on the lathe, in reverse, by chucking a sacrificial mandrel of the same diameter and thread pitch, hooking the end of the wire round or under the jaw, against the direction of rotation, then holding the other end of the wire under tension with pliers and starting the lathe dead slow. Once wound and removed from the mandrel, the ends must be trimmed then it should be screwed on to the threaded work to provide a surface to chuck on.<br />
<br />
=== Faceplate Work ===<br />
Faceplate work is probably the most dangerous operation you can (or rather should) perform on a lathe. The working area is a large diameter spinning surface with protruding clamps to fixture the part that it is impractical to guard. Protruding clamps, studs, nuts etc. are very difficult to see at speed.<br />
<br />
'''Treat the faceplate with great respect and caution if you wish to continue to be able to count to ten on your fingers!''' <br />
<br />
The 65 mm cross-slide travel vs the 80 mm faceplate radius is a serious limitation that may require creative compound, toolpost and tool setups for larger parts, and doing full face cuts in two sections.<br />
<br />
''It is common practice to skim the faceplate to ensure it runs true. We have not (yet) done this, and wont till the spindle is in better bearings and the nose reground to minimise runout.''<br />
<br />
==== Clamping ====<br />
Open ended/sided clamps should be oriented so that cutting forces drive the work towards the clamping bolt/stud, not out from under the clamp. Minimize the protruding length of thread past the clamping nut, if necessary using sacrificial bolts or studs you can cut to length, or even using a long M8 stud for one of the faceplate mountings, so you can get a clamp nearer to the faceplate center. Double-check all clamps are secure, manually turn the faceplate to check the work and clamps clear the ways, top-slide and toolpost, and stand out of the 'line of fire' (a disc extending from the faceplate) when spinning up the work for the first time. <br />
<br />
If you need to machine close to a clamp, consider marking a safe limit circle on the faceplate and work with a marker pen to make it easier to see how close the cutting tool is to crash disaster. <br />
<br />
I strongly advise reading chapter two of Tubal Cain's book "Workholding in the Lathe" several times before your first faceplate setup, and if possible get another experienced lathe user to check your first few setups before spinning them up.<br />
<br />
==== Chuck Guard Removal ====<br />
The faceplate is too large diameter to fit under the chuck guard, but the guard has an interlock switch wqhich must be closed for the lathe to run. The guard is now fitted with wing nuts so it can be removed allowing the the interlock switch to close when using the faceplate. It *SHOULD* *ALWAYS* be refitted if a chuck is fitted, except when turning work too large to clear the guard. <br />
<br />
''The chuck guard is primarily there to make it very difficult to start the lathe without removing the chuck key and to reduce the area of large diameter spinning surface exposed. It may slow down the projectile if a chuck sheds a jaw but is unlikely to stop it. Also it serves to contain coolant spray spun off the chuck. As we don't use flood coolant this usually isn't an issue for us. As setting up for faceplate work doesn't use a chuck key, and the most hazardous zone is the face of the faceplate, with its spinning projecting clamps, with full access required for machining operations, which a guard would not cover, the consensus is that removing the guard is an acceptable risk.''<br />
<br />
=== Turning and Facing ===<br />
We are getting good results in aluminium, brass, and even steel using HSS cutting tools in quick-change tool holders, and the ~ 94 um/turn power feed. Unfortunately due to lack of rigidity in both the machine and smaller diameter parts, if you don't want the outer end to be over diameter, a light final cut and multiple 'spring' passes will probably be required.<br />
<br />
For aluminium, a sharp HSS tool and 0.5 mm (20 div) depth of cut gives good results with power feed for rapid stock removal. Its also easy maths as each cut takes ~ 1 mm off the diameter. Finish cuts should be much finer, 0.1 mm (4 div) is 'in the ballpark'.<br />
<br />
For steel, using carbide insert tooling, a 0.25 mm (10 div) depth of cut is more appropriate, and with pre-applied cutting oil, gives reasonable results with power feed if you use enough speed. The maths is not quite so easy as you are only taking 0.5 mm off the diameter per pass. Again, use finer finish cuts but try to plan your cuts so the final cut is still cutting, not smearing the surface!<br />
<br />
When facing or parting off, some skill is required to turn the cross-slide handwheel steadily to get a decent finish and to avoid shock-loading the tool tip. Increasing the spindle speed in one or more steps to keep up with the reducing diameter is advisable, but avoid speeds that cause resonances (resulting in chatter). When parting off, small through-hole parts may be caught on a thin rod chucked in the tailstock, and pre-positioned inside the work with its tip right up to the parting off position.<br />
<br />
==== Using the Steady Rests ====<br />
For the fixed steady rest, see Blondihacks' Lathe Skills #26 - How To Use a Steady Rest! [[#Youtube_Playlists_&_Videos|{below}]]<br />
<br />
Ours doesn't have ball bearing fingers, so a smooth surface on the work and adequate lubrication are essential. The thumbscrews can only tighten the fingers, so for small adjustments outwards you need to either slack off the clamping nuts or ease them slightly and use a drift against the back of the finger's slot. Once set, check the chuck still turns freely.<br />
<br />
The traveling steady rest needs to run on a machined surface, so at least for the first pass, must follow the tool, so its difficult to avoid using more compound slide overhang than is desirable. An initial surface should be cut next to the chuck or tailstock center before fitting the steady rest.<br />
<br />
Both are a PITA to fit - the fixed one has to have its clamping post inserted up through the bed, and the supplied spanner is useless near the headstock, and the travelling one's mounting holes on the saddle almost invariably need swarf picked out of them.<br />
<br />
==== Turning Between Centers ====<br />
<s>Using a MT3 to MT2 reducing sleeve, the MT2 dead center can be fitted in the spindle.</s> ''Currently the MT3 spindle taper is compromised.'' Alternatively, a soft center can be turned immediately before use in the three jaw chuck, but that must have its 60° point re-cut to concentric if the chuck is disturbed, and needs to be either large enough to bear on the chuck body, or must have a lip to bear on the end face of the jaws to take the axial thrust. Recutting the center is a PITA, as the compound angle must be set to 30° anticlockwise, then reset to a true 0° afterwards. Maybe a right-hand 30° end angle zero rake form tool is the answer, or use the carbide insert tool SSKCR0610H06 as a form tool with the toolpost rotated 15° anticlockwise.<br />
<br />
With the MT2 live center in the tailstock quill, this gives us a center either end of the work to hold it.<br />
<br />
We also need a drive dog similar to [https://littlemachineshop.com/products/product_view.php?ProductID=4473&category=1 this], and the corresponding drive post to bolt to the spindle nose. I have some 25mm bore thick wall iron pipe, which should do nicely. Lengths of the dog's straight tail and of the post TBD after I check how much the center protrudes. N.B. its recommended to tie the tail to the post to keep them in contact so they don't slam. ''Currently we will need to drive from the chuck jaws. Possibly use the exterior jaws with a short soft center gripped on the inside end and drive from the highest step.''<br />
<br />
=== Drilling ===<br />
Always start with a center drill so deflection of longer bits doesn't start the hole off-center. For larger bits (> 5 mm), first drill to the web size, then to final diameter. For a precision hole, drill slightly undersize and ream to final diameter. ''Supply your own reamers!''<br />
<br />
Caution: See note about the quill anti-rotation pin in section [[#Tailstock Quill|Tailstock Quill]] above.<br />
<br />
=== Boring ===<br />
Caution: As the spindle doesn't extend right through the headstock housing, if boring in a through hole, chips tend to fall out the back and tumble in the spindle bore till they fall into the change gears. To avoid this, one should plug the spindle bore with a wad of paper towel or rag and when cleaning up afterwards, use a rod to push it through towards the tailstock, with the chuck jaws (if fitted) wound clear of the spindle bore.<br />
<br />
A swivel bladed hole deburring tool (pale blue handle) can be found in the main room on the windowsill behind the drill press.<br />
<br />
A couple of boring jobs have been bodged with an awkwardly angled turning tool and achieving acceptable effective rake with enough clearance to reach deep enough into the hole has been problematic. I reviewed the tools we had and found none suitable for starting out in a 13mm bore, the max diameter we can (easily) drill. I therefore decided to buy a set of boring bars and make a holder for them. I had difficulty finding anything affordable under 10mm shank - the best low cost option was a [https://www.amazon.co.uk/dp/B07P5LGVBX set of nine 3/8" (9.525 mm) shank brazed carbide tipped boring bars], which would be close to the max capacity of the quick change boring bar holder - if we had one! Unfortunately this holder for our specific toolpost is difficult to find except in a toolpost bundle. Another annoyance is the variable tip height of the set, varying from 1.8 mm to 2.8 mm above the center of the shank.<br />
<br />
I therefore decided to make a boring bar holder of the [https://littlemachineshop.com/products/product_view.php?ProductID=1700 Littlemachineshop.com (USA) style] for use in the four way toolpost, as the additional rigidity will certainly help. Starting with a slightly over 50 mm length of 16 mm aluminium square bar and using the four jaw chuck , both ends were faced and an attempt was made to find its center and center drill it. It was then drilled out to ~9.8 mm after much drama due to blunt drills and drills that cut ~1mm oversize. Too big, but beggars cant be choosers as we didn't have a boring bar holder or a 3/8" reamer. Unfortunately the final hole ended up significantly off center. It was then chucked crossways and ~1 mm skimmed off its thickest side to gain clearance to allow it to be shimmed to height, then one side was slit lengthwise manually with a hacksaw.<br />
<br />
It was fitted to the for way toolpost and loaded with a booring bar, which clamped firmly. A 0.86 mm shim stack brought the tip of the largest boring bar almost spot on center height, with the difference easily accommodated by twisting the tool slightly. The three jaw chuck was then remounted, and a piece of iron pipe chucked for a test. It cuts well and leaves a decent surface finish.<br />
<br />
''The boring bar setup is a work in progress - talk to me before attempting to use them if you have a project that would benefit from boring..''<br />
<br />
ToDo: get something that can sharpen tools tipped with this grade of carbide - it needs some sort of diamond (or possibly CBN) wheel as green grit silicon carbide does little more than polish it. ''N.B. diamond wheels are rapidly eroded by grinding steel, so the supporting steel seat must be undercut with a regular grinding wheel before the diamond wheel can contact it.'' <br />
<br />
We'll also need 50 mm square sheet shims to fit under the toolpost to gain clearance in the toolpost above the tool or toolholder. A 2.4 mm shim would give us about the same above and below spindle center height, and we probably need a small selection of thinner ones.<br />
<br />
=== Thread Cutting ===<br />
The objective is to cut a thread that complies with the ISO metric thread profile. Our lathe is not currently equipped to cut non-metric threads, (with the exception of BA which have pitches based on metric threads of that era).<br />
<br />
[[File:ISO and UTS Thread Dimensions.svg|frame|center|Metric Thread Profile - from the geometry, H is ~86.6% of P]]<br />
<br />
Metric thread data - See 'Preferred Sizes' at: https://en.wikipedia.org/wiki/ISO_metric_screw_thread<br />
<br />
See "Mini Lathe User’s Guide" section '''Threading''' for general techniques *ONLY*, and above for change gears and threading dial setup.<br />
<br />
Amadeal specify the max. thread pitch as 2.5 mm. Any thread pitch greater than 1.5 nn requires the change gears to gear up. When gearing up it is desirable to distribute the ratio as evenly as possible over the two pairs of gears in the geartrain to avoid excessive tooth loading.<br />
<br />
==== External Threading ====<br />
Initially turn work to required Major Diameter, set up change gears and threading tool, touch off on the work, zero the top and cross slide dials, and do a 'scratch' pass to check the pitch. Back off the tool using the cross slide, return the carriage, and re-engage the half nuts on a valid dial line clear of the end of the thread then immediately stop the lathe, and hand turn the chuck till the tool tip is (hopefully) over the scratch to check the thread pickup. If all is good, return the carriage again, restart the lathe, bring the tool back in and start cutting your thread. <br />
<br />
Methods of doing so vary depending on the size of the thread and toughness of the metal, but straight-in plunge cutting is generally to be avoided as has the highest cutting forces, and does not reliably keep the carriage (and top-slide if set parallel to the work) loaded to avoid pitch errors due to backlash. It is common practice to set the compound angle so the cross slide is nearly parallel to the trailing flank of the threading tool tip, so all the cutting action is at the tip and leading edge. The angle should be fractionally steeper so the trailing flank rubs slightly to avoid deflection. Use a side notch on the fishtail gauge, held against the work, to set the tip exactly straight in to the work. <br />
<br />
After each pass, back the tool out using the cross slide, return the carriage to the start and bring the tool back in to exactly the same cross slide position, before advancing the compound by the depth of the next cut. The depth of cut must decrease as the thread depth increases as the width of the cut increases proportionately to the total depth, which would otherwise result in excessive cutting forces.<br />
<br />
If leaving the half-nuts engaged and reversing the lathe to return to the start of the thread for the next pass, its absolutely essential to back the tool out of the thread for the return pass as it will not follow the path of the cutting pass due to backlash in the geartrain, leadscrew mounts and half-nuts.<br />
<br />
==== Internal Threading ====<br />
''<nothing here yet>''<br />
<br />
== Cutting fluids ==<br />
=== Why bother? ===<br />
[https://youtu.be/mRuSYQ5Npek Watch this video] and contemplate what's actually happening to that thin ribbon of metal being removed. Most of the lathe's motor power is being turned into heat by internal friction in the chip being removed in the zone around the cutting edge, and surface friction at, and immediately behind the cutting edge, near-instantly heating the chip by up to several hundred degrees. Reducing the surface friction using a suitable cutting oil reduces the strain on the machine as a whole, and reduces workpiece and tool heating (and thus expansion) with consequent improvements in maximum usable feed and depth of cut, surface finish and accuracy. It also drastically increases the life of the cutting edge.<br />
<br />
=== Practicalities === <br />
We don't have a coolant system for the lathe and *really* don't want the maintenance hassles of using soluble cutting oil/coolant as if used infrequently its a PITA to keep recirculated high water content cutting fluids from going rancid and stinky, and they can also rust the ways, so even a total loss gravity feed system is problematic. Therefore if dry machining doesn't give a good enough finish, we tend to use oil applied topically, by hand to the work. <br />
<br />
* Hard brass is typically free-turning without oil, however some light oil for the final cut can improve surface finish, but with the disadvantage that it will increase loose chip buildup on the tool as hard brass typically forms short spalls or splinters rather than curly chips.<br />
<br />
* Many Aluminium alloys tend to be gummy, and Paraffin or other mineral spirits mixed with a little oil can help prevent the aluminum welding to the tool edge. WD40 will do at a pinch, but its messy to apply from a spray can.<br />
<br />
* Steel really needs *GOOD* cutting oil. Lard oil is the traditional choice for steel. If there are any objections to lard oil, we should bite the bullet and get some commercial dark high Sulphur cutting oil, but beware, many such oils use an additive package that includes lard oil.<br />
* Cast iron (except ductile) should be cut dry, as the carbon micro-inclusions self-lubricate it, and the carbide in the dust (primarily Cementite) are very abrasive, so tend to form a grinding compound if mixed with oil. <br />
<br />
I've sorted out an oil pot lid with a 1/2" brass collar soldered in to give a nice smooth sided hole, for ease of use and to minimize the risk of spills when using a brush to apply cutting oils, and got some dirt-cheap brushes. It fits Shippam's paste (and similar own-brand spread) jars and I've found several jars and ordinary lids to seal them for storage. Unfortunately it isn't the easiest to get this type of jars' lids back on square so they seal properly, and if you over-tighten them and there's a temperature change, they can be a total <expletive> to reopen. Using the rubberised handles of a large pair of pliers to grip the jar lid just above its rim is the best option, and avoids damaging the lids.<br />
<br />
''N.B. For the smaller brushes, the glue holding the bristles in is attacked by paraffin. To prevent loss of bristles, crimp the aluminium ferrule of each new brush of this type before use.''<br />
<br />
We have, in labelled jars:<br />
<br />
* Sulphurised Lard oil thinned with paraffin. Best choice for heavy cuts and threading in steel but stinky.<br />
* Lard oil thinned with paraffin. Good for steel and acceptable for softer copper alloys<br />
* Paraffin with a trace of light oil. Good for aluminium, and can help prevent squealing chatter on finish cuts in brass.<br />
<br />
I've also got some paraffin wax (in the form of a stubby candle), which can be applied lightly (under power) to brass and aluminium stock especially on the finish pass. It makes less mess than oil but unfortunately tends to build up on the tool tip, making it difficult to 'work by eye' without frequent pauses to clean the tool tip.<br />
<br />
We've also got a tin of [https://www.rocol.com/products/rtd-compound Rocol RTD cutting compound], which is a thick paste. Its highly recommended for drilling and tapping steel (in the drill press or by hand), but as a paste, is less useful for general lathe work unless thinned to a fluid consistency, e.g. with paraffin or white spirits. OTOH its certainly worth trying for high speed facing steel as it is less likely to get flung off.<br />
<br />
== Cleaning and Maintenance ==<br />
Swarf is a significant cut hazard to the operator, especially stringy swarf from cutting steel. Never touch it bare-handed - always use a tool e.g. a brush, or a hook, or needle nose pliers for grabbing long swarf.<br />
<br />
* After use, brush all swarf off the toolholder, compound and cross slide etc. ways and leadscrew, brushing towards the rear to avoid sweeping chips under the carriage. Ian B has blocked off the opening at the headstock end of the rear splashguard (to try to keep swarf out of the motor), so one must sweep the swarf towards the open tailstock end and catch it in the metal dustpan. Preferably, also thoroughly clean out the chip tray under the lathe, but at least sweep out visible swarf.<br />
* Wipe up any cutting fluid residue and re-lubricate affected sliding surfaces with way oil.<br />
* Do not solvent clean the chuck guard, as it will make the plastic brittle, or even craze it. Water with a little detergent is permissible for cleaning it, with the guard totally removed from the lathe.<br />
<br />
Before engaging the half-nuts for power feed/threading, check the leadscrew is clean! ''Best cleaned under power, with a toothbrush.'' <br />
<br />
'''Caution:''' The traverse gears behind the carriage handwheel are in an open-backed housing and tend to become packed with swarf! Swarf buildup here will result in jerky carriage movement. Clean out as much as you can with a toothbrush ...<br />
<br />
===Lack of lubrication and/or swarf or dirt build-up can be disastrous===<br />
* If using the change gears/power feed, lack of lubrication of the B-C stub shaft center pin or either leadscrew end bearing can result in seizure and immediate destruction of one or more gears in the gear train or worse. <br />
* Small pieces of swarf can get between the saddle and ways, or into the slides degrading accuracy, possibly permanently if hard swarf scores them, or jamming them. The carriage handwheel gears behind the apron are notorious for accumulating swarf, and swarf buildup on the leadscrew can prevent the half-nuts engaging properly, resulting in scrapped work, and possibly stripped half-nuts. <br />
* Metal swarf can get into the motor (''though Ian B has modified the rear chip catcher to reduce the risk)'' or into the control box via the leadscrew, and short-circuit stuff. At best it will blow the fuse and need a strip-down to clean it out, at worst it may require a replacement [https://www.amadeal.co.uk/acatalog/Speed-Control-Circuit-Board--12amp-AMA_SP_CJ18_SCB12.html#SID=12 speed controller] ''(currently £96)'' and/or [https://www.amadeal.co.uk/acatalog/550W-motor-for-CJ18A-Mini-Lathe-467.html#SID=240 motor] ''(currently £105)'' and possibly other electrical parts. We should probably fit a [https://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C3-Mini-Lathe-Spares/C3-256-Leadscrew-Grommet-Dustproof-Cover C3-256 Leadscrew Grommet] to keep swarf out of the control box, as it tends to drop onto the 'Filter' board which is mounted horizontally, below the leadscrew.<br />
* Grit from grinding, sanding etc. forms a grinding paste with the way oil, and will rapidly wear out the ways, saddle and slides. Keep grit off at all costs e.g. by covering the ways and slides during grinding/sanding operations, and if there's any chance grit has gotten where it shouldn't, clean and re-lubricate *BEFORE* moving the carriage or slides, then move the carriage and slides, wipe down where they were with a clean paper towel and check there's no remaining traces of dirt other than clean way oil on the paper towel. If it doesn't come clean when you re-lubricate and move it again, a full strip down may be required to solvent clean and relubricate the precision sliding surfaces.<br />
* Although a metalworking lathe *can* be used to turn hardwood, wood dust and small chips are extremely pernicious, as they get everywhere, even clinging to clean surfaces, are abrasive due to their silica content, and are hygroscopic, promoting rust. An even more thorough clean-up than after using abrasives is needed, immediately afterwards. Oily wood dust and fine wood chips in significant quantities are a fire hazard, even in the trash bin.<br />
<br />
===Lubrication===<br />
See section: "Lubrication" in LittleMachineShop.com "Mini Lathe User’s Guide" [[Ian_M's_Lathe_Notes#Manuals|(below)]]. As we usually only open two nights a week, in the table on page 16, Daily lubrication becomes Weekly and Weekly becomes Monthly.<br />
<br />
===General Maintenance===<br />
* The grubscrews holding the cross-slide and compound slide dials tend to loosen due to vibration and use of the dials. Keep them snugged up, but not so tight the dials cant be set without an Allen key.<br />
<br />
* The screws holding the cross-slide nut tend to work loose due to vibration. Crank the handle to and fro through the backlash and visually check there is no movement of the screw heads in their holes. If there is, see the [[#Excessive_cross-slide_backlash|notes below]].<br />
<br />
===Removing the Carriage===<br />
Its possible to remove the carriage from the bed for cleaning etc. without dismantling it. The only stop to its motion is the righthand leadscrew bearing.<br />
<br />
Start by removing the tailstock. Crank the carriage to the tailstock end then remove the leadscrew bearing (two screws and a nyloc nut on the leadscrew end). With the half-nuts open, hold the leadscrew centered in them and crank the carriage off the end of its rack, then slide it off the end of the bed.<br />
<br />
Refitting is the reverse of removal, except (if its gibs are correctly adjusted) the carriage will be very tight on the end of the bed ways so may be difficult to work onto the ways without a stack of blocks of wood or similar to support it at exactly the right height. The righthand leadscrew bearing must be refitted with the carriage as close as possible to it and the half-nuts firmly closed to support the leadscrew at the correct height to hold it in alignment while the screws are being tightened. The nyloc nut controls leadscrew end-play. Fully tighten it then back it off slightly till the leadscrew turns freely with its change gear removed.<br />
<br />
If the Apron has been off, refit it with the screws no more than lightly finger tight and only finally tighten them after checking lead screw engagement at both ends of the carriage travel and that the rack and pinion operates smoothly over the full travel.<br />
<br />
== Issues and Annoyances ==<br />
As of September 2023 - mostly resolved, apart from the spindle bearings and runout, the lathe is in better condition than it has been for a number of years.<br />
<br />
===Four Jaw Chuck has two jaws too tight===<br />
Fixed 27/10/2023: Two of the chuck jaws were tight in their slots, making precise adjustment difficult due to lack of 'feel'. Moving the jaws round the slots showed the problem mostly followed the jaw not the slot. The grooves in the opposite sides of the affected jaws that run in the chuck slots were slightly out of true, and the rails either side of the slots were slightly too thick towards the center. Due to the difficulty of seeing the high spots, after cleaning up and deburring the jaws didn't do enough to ease them, I decided to grind the top of the rails where they were binding. Several repetitions of spotting with Engineer's blue, grinding, then diamond filing the high spots has eased them enough. I cleaned everything, greased the jaw slides and screws, and refitted the studs so the chuck is now fit for service.<br />
<br />
''N.B. Don't move the jaws to a different slot - the formerly tight jaws *must* stay in the slots furthest from the makers mark.''<br />
<br />
===Excessive Runout===<br />
Mostly fixed 24/10/2022: I ground the chuck seating surface of the spindle nose (outside lip) to under half a thou runout. This also cleaned up several burrs. It would be possible to do better, but that would need good spindle bearings, and a more rigid toolpost grinder mount.<br />
<br />
Our spindle nose was damaged years ago by a person with little mechanical aptitude (who shall remain nameless) beating it up with a hammer mushrooming the spindle nose. We are getting several thousandths runout at the end of the MT3 bore, a MT3 to MT2 reducer sleeve in it runs visibly out of true, as does the spindle nose flange. When you put a chuck on it, the runout is magnified by the distance from the spindle nose. Ideally we would replace the spindle when we change the bearings but its £52 [https://www.amadeal.co.uk/acatalog/4-Spindle-Upgrade-Real-Bull-Mini-lathe-CJ18-series-AMA_SP_CJ18_003RB.html#SID=9 from Amadeal] and money is tight. It may well require more work after the bearing upgrade. Once good bearings are in, if we can borrow a decent MT3 arbour as a reference, we should consider skimming the bore.<br />
<br />
===Spindle bearings===<br />
* The spindle bearings appear to be close to worn out. They are notably noisy when running, and there appears to be more slop in the spindle than is desirable. There is notable resonance around 600 RPM, and surface finish of end faces is often poor. We have some ideas for possible replacement/upgrade, but it requires a major teardown.<br />
<br />
: The original bearings are allegedly 6206-2RS or 6206-ZZ deep groove ball bearings - 2RS codes rubber seals both sides and ZZ codes metal shields. Although the deep groove gives reasonable ability to withstand axial loads, the bearing balls point contact means they are vulnerable to [https://en.wikipedia.org/wiki/Brinelling brinelling] due to shock loading. The jammed on three jaw chuck didn't help this, as before we skimmed the spindle nose lip, it had to be driven off using a bar through the spindle bore, shock loading the bearings every time. Also even a minor 'crash' could have brinelled them due to eccentric shock loading, and the lathe has previously been crashed badly enough to need drive gear replacement. There are also issues with the 'approved' method of spindle and bearing removal from the headstock brinelling them, even if you don't abuse the spindle nose with a hammer!<br />
<br />
: A possible replacement is 30206 tapered roller bearings. The new bearings are slightly thicker so the plastic spindle spacer (15) needs to be machined to length to get the 45 tooth spur gear that drives the change gears laterally aligned with the tumbler gears. If a temporary replacement (3D printed?) is fitted, the lathe can be run (without power feed capability) so this can be done on the lathe after fitting the new bearings. As tapered roller bearings have line contact, they are significantly more resistant to brinelling.<br />
<br />
: ''See [[Talk:Ian_M%27s_Lathe_Notes]] for notes, links etc. for this upgrade.''<br />
<br />
===Motor stuttering===<br />
* Fixed 21/09/2023: The motor was running very erratically and it was very difficult to set a speed. Several loose connections were found in the control box, mostly loose female spades to the motor controller board, but also a dry jointed braking resistor on the 'Filter' board, and an inhibit wire completely off its terminal on the forward/reverse switch, making intermittent contact. After tightening and/or remaking all affected connections, it was much improved but still not right below 300 RPM. The remaining issues were due to poor wiper contact in the speed control pot, and stripping it, cleaning the track and contact ring and re-tensioning the contacts resulted in the motor now running smoothly over the full speed range. The speed is slow to settle, and while part of that is probably the lag in the digital tach, I suspect that the KBIC motor speed controller isn't properly tuned as it was (allegedly) previously replaced.<br />
<br />
===Drive belt slipping===<br />
* Fixed 28/9/2022: During testing the motor after the above issue, it was noted that the chuck could be stalled, slipping the drive belt, with not much torque. The drive belt was determined to be loose and a bit worn, but still in acceptable condition. <br />
<br />
: Access for servicing the belt requires removing the control box ''(2 spades to ZVR switch disconnect the supply, speed sensor and motor simply unplug from the 'filter board')'', the motor cover, chuck guard switch assembly + wiring cover, the change gear 'A' (drive) shaft carrier assembly, and the tumbler gear assembly. See https://youtu.be/EkxlIz01BdA for disassembly/reassembly, though on our lathe, the speed encoder ring on the spindle prevents the belt cover from being fully removed without disturbing the spindle nuts. There is enough room to work with it loose, but still trapped by the encoder ring. Also, unlike the video, if the 'jack' screws under the headstock are correctly adjusted, and the studs aren't excessively bent, there is no need to make custom studs. <br />
<br />
: It turns out that our lathe was missing the M6 hex headed jack screws that press the motor down to resist the belt tension, and the motor had cocked out of position at a severe angle. I know Ian B had had considerable trouble adjusting it after the motor fault back in October 2022, and I believe it had been getting slowly worse ever since. The jack screws were probably mistaken for headstock fixing bolts during disassembly after the crash that resulted in the metal Hi/Lo gears being fitted, then lost. The penny washers on the studs had dished, so I turned them over and backed them up with smaller washers and switched to Nyloc nuts so they cant back off due to vibration. N.B. There is a packing washer on the motor side on one of the studs, presumably so the shaft is true to the ways. Adjusting the motor is awkward to say the least. One has to slack the stud nuts off a lot, pry under its rear end to lift it enough to be parallel to the ways, snug the stud nuts, check alignment, then set the jack screws and their lock nuts to hold it there, and finally tighten the stud nuts. <br />
<br />
: Tension: According to Sieg, it should be possible to twist the belt 90° mid span with a light finger grip. Other sources say 1/32" - 3/32" deflection mid span with light finger pressure.<br />
<br />
===Speed display blanking===<br />
* The speed display has been intermittent, blanking and flashing 8888 and 0 at certain speeds for as long as I have been using the lathe. Finally on 18/07/2022 it failed completely, with no display. I removed the display module and bench tested it - the pins are labelled 5V GND PL PE, PE is frame ground and PL is a TTL level pulse from the speed sensor - confirming that it was in good working order. My suspicions then turned to its power supply on the 'Filter' board. With both the sensor and display unplugged, the 5V rail was found to have a only a couple of volts, but the unreg DC was 17V and stable. Replacing the 78L05 5V regulator restored the 5V rail and normal operation.<br />
<br />
: ''I conclude its been failing for a while with high load current due to speeds with more lit segments causing it to drop out, resetting the speed display, causing it to blank, lowering the current enough for the regulator to recover, then the display MCU lamp tests (8888) then re-acquires the speed, repeating ad-nauseum till the speed is changed. I don't like the design as the high input voltage results in excessive dissipation.'' <br />
<br />
: ''ToDo: If it fails again, bench test display to measure its worst case current consumption, then fit an appropriate dropper resistor to reduce the 78L05 dissipation.''<br />
<br />
===Quill spinning when drilling===<br />
* The quill was tending to spin while drilling because its anti-rotation pin (a M5 dog tip setscrew) was sheered. I've removed the debris, aligned the scale with the top of the tailstock and fitted a longer M5 dog-tip setscrew to replace it, with a nut to lock it at the correct height. N.B. the pin isn't that 'meaty' so if using big drills in tough metals, to prevent shearing it, it should be backed out so the quill can be turned by hand and unwanted rotation controlled by being quick with the quill lock if it starts to spin, or even using a close fitting rod in one of the chuck key holes with plastic tube over it to protect the ways. <br />
: ''If the screw sheers again, the quill will need to be removed and the tailstock taken off the lathe so the sheered tip can be shaken out, and if the setscrew is difficult to remove it probably means the threads are mangled where it sheered. Try driving it right through with the quill out.''<br />
<br />
===Sloppy quick change toolpost locking mechanism===<br />
* Once the dovetail clamp screw was slackened, there was nothing preventing the dovetail twisting or cocking significantly, and friction with the toolholder made it tend to do so, making toolholder insertion and removal more difficult unless the clamping screw was backed off excessively. I added a compression spring around the clamp screw inside the toolpost to push the dovetail outwards so it mostly retains alignment when open, allowing toolholders to slide on or off cleanly with far less screw slackening.<br />
<br />
===Leadscrew rubbing===<br />
* The leadscrew shaft is rubbing on the insulating separator inside the control box. Unfortunately the corner of the relay on the Filter Control Board (#160) doesn't allow enough clearance. Although the friction isn't much of a problem at high reduction ratios, e.g. 16:1 power feed, it increases the stress on the change gear train, and may be problematic when threading at feeds above 1:1. ''Possibly pack out the control box mountings by a couple of mm.'' <br />
<br />
===High/Low lever backwards!===<br />
* The high-low drive gear selector behind the headstock is incorrectly labelled and differs from the manual: low gear (which we normally use) is with the lever towards the tailstock. ''I suspect that the gears in the headstock were refitted the wrong way round when it was upgraded to metal gears.''<br />
<br />
: ''ToDo: Get it reassembled the right way round during the spindle bearing upgrade!''<br />
<br />
===Carriage lock fouls top slide===<br />
* The T handscrew has been replaced with a M5 hex headed bolt, to permit access when the top slide is over it. An 1/4" drive 8mm socket is usually left on it, but needs to be removed when the full cross slide travel is needed. The small (4 jaw) chuck key is near enough 1/4" to use for it. If you need to (un)lock it while the compound is over it, you'll need an 8mm spanner. ''The [https://www.amadeal.co.uk/acatalog/Mini-Lathe-Carriage-Lock-463.html Amadeal lock screw] is in the spares tin as it was too high and fouled the compound slide.''<br />
<br />
===Tailstock locking lever loose===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock - See full image for key to screws]]<br />
* Diagnosed and fixed 10/1/2023 - In the base of the upper section of the tailstock, there are two dog tip set screws that engage with locating grooves in the counter-rotating shafts carrying the eccentric locking cams. They'd backed off, probably due to vibration. They need to be tightened till they bottom out in the groove, making sure they are '''in''' the groove, backed off half a turn so the shafts can turn easily, and locked in place. There's no facility to do so, so reassemble with weak threadlocker. Unfortunately to get to them you have to remove the tailstock base slide, which is held on by the pressure of four adjusting grub screws, which all need backing off, and one socket headed bolt from underneath so full tailstock realignment is required after reassembly, which even for a rough alignment is tedious.<br />
: <s>The tailstock locking lever is loose and can be pulled out on its axis. It works OK when fully pushed home but needs investigating. ''I tightened the grub screw as the lever was coming off its shaft, but the whole shaft pushes/pulls in and out. It works OK fully pushed in, but it seems something that is meant to retain it has failed inside the tailstock base.</s><br />
<br />
===Gear alignment issues===<br />
* Change gear alignment is poor. I've currently got a gapped washer (to clear the key) packing out the A shaft so the gears line up, but this reduces the key's engagement so is problematic due to the high loading if the gears are set up for coarser threads. <s>Also I need to turn down some penny washers to slightly less than the root diameter of the metal 20T pinions, as gear retaining washers.</s> ''The gear retaining washers for A gear and B-C stub shaft are now done, turned down to slightly under 16 mm dia. Spares in the change gear tin. ToDo: The D (leadscrew) washer requires a larger center hole, so make two more with that hole.'' <br />
<br />
===Saddle gibs loose===<br />
* Fixed 11/04/2023: I took the apron off for access (and to clean the carriage handwheel gears), and found the front sheer plate screws were completely loose. I've snugged them up some and set the opposing grub screws and got a lot of the slop out. I've re-checked the front ones, and taken up the slop in the rear ones - Unfortunately it wasn't possible to get carriage movement to have an even 'feel' over its whole travel, and its noticeably tighter near the tailstock. If light hand pressure on the side of the unlocked carriage can cause movement (with the half-nuts open), its time to readjust them again, though it should be possible to move the carriage with a firm push. <s>The saddle gibs (actually the sheer plates) were too loose, to the point that engaging a slightly stiff threading dial could cause it to self-feed, an obvious crash hazard if working near the chuck or a step in the work.</s><br />
<br />
''N.B. the lefthand front opposing grubscrew is short, (fully recessed) and unlike the others does *NOT* have a locking nut as it must clear the traverse pinion. A wrap of PTFE tape provides enough friction to keep it in place, though possibly a bit of nylon fishing line down its hole would be better.''<br />
<br />
===Excessive cross-slide backlash===<br />
* ''Fixed 21/11/2023.'' Originally, back in October 2023, The cross-slide screw had excessive backlash (nearly three turns), which increases the risk of loosing track of the cut depth when cutting steps, and during threading operations. If you ended up off by a turn too far in, a crash would be the most likely outcome.<br />
: The original excessive backlash was traced to loose cross-slide screw nut mountings. The nut has two socket headed cap screws pulling up, one either end, accessible from the top of the cross-slide, which control the tilt of the nut to take up backlash in the nut, and an opposing grub screw pressing down on the center of the nut to make it longitudinally rigid. Snugging up the grub screw reduced the backlash to 10 divisions or so, or 0.25 mm. A year later, the backlash had increased to one turn due to the cross-slide nut mounting screws working loose again.<br />
<br />
: 07/11/2023: I investigated further: It is difficult to get the cross-slide nut aligned correctly as it must be at the same height as the screw which is constrained by the bearing surfaces in the bracket. With the cross-slide almost at the front limit of its travel, I removed the screw and set the nut as level as possible and visually centered in the bore, then re-fitted the bracket and screw, then adjusted the tilt till it turned freely through the backlash. I then tilted it up at the front till some drag was felt to minimise the backlash and tightened the screws to lock it in place balancing them to maintain the same feel as I tightened them. The result was 7 divisions of backlash, acceptable but not great. During normal turning operations, the load on the nut is tension on the front screw and pressure on the grubscrew, so if it slackens again due to vibration from chatter, odds are it will be the rear screw that's loosened.<br />
<br />
: 16/11/2023 - 21/11/2023: The backlash had crept back up to 11 divisions (0.275 mm). We don't have any >14 mm brass stock (or even near that) so I tried making the shim washer out of aluminium. I was shooting for 0.24 mm but due to poor technique got 0.28 mm. No good - locked solid. I lapped it down and tried it till I got it down to 0.20 mm which gave about 3 divisions backlash - good enough, but the screw was too tight due to the shim washer not being bevelled at its outer edge resulting in it cupping in its seat. Filing a bevel round the OD and re-lapping it resulted in a 3 - 4 divisions of backlash. Its a little mushy due to the washer having been kinked removing it, so ideally a new (brass) washer should be made. <br />
<br />
* Further reduction of backlash: https://youtu.be/Wu_tI29JL2Y?t=163 <br />
: Brass tinned with Pb-free solder to form a white metal bearing surface should work at least as well as the bronze used in the video. The shim washer needs to be 10.2mm ID, with a full thickness bevel on a 14 mm OD. It isn't necessary to remove the lead screw from the cross slide, as the washer can be fitted in-situ with only the bracket removed.<br />
<br />
===3 Jaw chuck didn't mount properly===<br />
* Fixed 7/4/2023 by grinding the spindle nose lip. The three jaw chuck can now be installed and removed by hand with no hammering. A test bar in it now has only 2 thou runout (TIR) at the chuck.<br />
: <s>The three jaw chuck and the faceplate aren't seating properly on the spindle nose. Its too tight on the register diameter of the lip. This results in grossly excessive runout, and also makes this chuck and the faceplate a PITA to fit or remove.</s><br />
: ''The spindle nose had been abused with a hammer (before my time) which mushroomed it and may have brinelled its bearings. See '''Excessive Runout''' and '''Spindle bearings''' above.''<br />
<br />
== Manuals, Books and other resources ==<br />
=== Manuals ===<br />
The [https://wiki.richmondmakerlabs.uk/images/a/a3/Lathe_InductionNotes.pdf RML CJ18A Mini-Lathe Induction Notes]. Your mandatory Lathe Induction will cover most of this but its good to be able to refer back to it. Also see [[:File:Lathe Induction Bushing.pdf|Lathe Induction Bushing]], which you will make during your induction, to introduce the four key lathe skills: facing, turning, drilling, and parting off. <br />
<br />
Official [https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Amadeal CJ18A Manual], or paper copy (less complete) kept on shelf above lathe.<br />
<br />
The [https://www.chesterhobbystore.com/wp-content/uploads/2022/11/Conquest-Super-Lathe.pdf Conquest Super Lathe manual] is considerably better than the Amadeal manual and is for a near-identical machine.<br />
<br />
The [https://littlemachineshop.com/images/gallery/info/minilatheusersguide.pdf Mini Lathe User’s Guide] from LittleMachineShop.com is even more comprehensive, going into its usage in some detail, with a proper TOC, and covers both US and Metric versions of Realbull Mini-lathes. ''The only fly in the ointment is the threading section assumes a US lead screw so change gear selections and threading dial divisions will not be correct for our lathe.''<br />
<br />
[https://www.arceurotrade.co.uk/machineguides/C3-Mini-Lathe-Dismantling-and-Reassembly-Guide.pdf Sieg C3 Mini-lathe Dismantling and Reassembly Guide] "A picture story book to help you dismantle and reassemble your Sieg C3 Mini-Lathe" ''It is similar enough to ours to serve as a maintenance guide, except for the electronics, spindle drive and other headstock innards.<br />
<br />
The motor controller is a clone of a [https://acim.nidec.com/drives/kbelectronics/-/media/kbelectronics/documents/dc-drives/manuals/kbic_manual.ashx?la=en KBIC® SCR DC Motor Speed Control]<br />
<br />
=== Books ===<br />
'''Metal Turning on the Lathe''', by David A Clark, Crowood Metalworking Guides, ISBN-13: 978-1847975232 [https://www.amazon.co.uk/gp/product/B00E78RKIG Kindle Edition (£8.99)]. ''A 'free' epub can be googled for, *NOT* linked here due to dubious legality.''<br />
<br />
'''[https://archive.org/details/03screwcuttinginthelathe Screwcutting In The Lathe]''', by Martin Cleeve (a pen-name of Kenneth C Hart), Workshop Practice series #3, ISBN-13: 9780852428382<br />
<br />
'''[https://archive.org/details/15workholdinginthelathe Workholding in the Lathe]''', by 'Tubal Cain' (a pen-name of Tom Walsh), Workshop Practice series #15, Argus Books, ISBN-10: 0852429088<br />
<br />
'''[https://archive.org/details/20metalworkandmachininghintsandtips Metalwork and Machining Hints and Tips]''', by Ian Bradley, Workshop Practice series #20, ISBN-13: 9780852429471<br />
<br />
'''[https://archive.org/details/38toolandcuttersharpening Tool and Cutter Sharpening]''', by Harold Hall, Workshop Practice series #38, ISBN-13: 9781854862419<br />
<br />
'''[https://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpaperT204.pdf Cutting Fluids]''', by EC Bingham, NIST Tech. Paper No. 204, 1921<br />
<br />
=== WWW resources ===<br />
==== Mini-lathe Specific ====<br />
There's a *LOT* of mini-lathe info online. Notable sites include:<br />
* http://www.mini-lathe.com/ - A major Realbull/Sieg mini-lathe resource.<br />
* http://mikesworkshop.weebly.com/lathe-modifications.html - many mods including carriage DRO autostop, and variable speed leadscrew motor drive, cross-slide motor drive, etc. He also has a page with a bunch of accessories, toolholders etc. - http://mikesworkshop.weebly.com/lathe-accessories-and-tooling.html<br />
* http://andysmachines.weebly.com/variable-speed-controls.html - Scroll down to the 'UPDATE' section for the schematic of a very similar SCR speed control board. It also has the schematic for an earlier version of the Auxiliary Control Board (aka: 'Filter' board).<br />
* https://www.youtube.com/watch?v=WbJM9ooveo8 - A video tour of a very very similar mini-lathe. Significant differences: ours has a 4" longer bed, a quick change toolpost, a different tailstock, no DRO (apart from basic spindle speed, so skip 16:12 to 28:50 in the video), larger chucks and a carriage lock.<br />
<br />
==== Forums ====<br />
''with publicly accessible archives''<br />
* https://groups.io/g/7x12MiniLathe - Mini-lathe specific, active<br />
* https://www.hobby-machinist.com/forums/mini-lathe-mini-mill-information.220/ - active<br />
==== Youtube Playlists & Videos ====<br />
* Blondihacks: [https://www.youtube.com/playlist?list=PLY67-4BrEae9Ad91LPRIhcLJM9fO-HJyN Lathe Skills] (playlist) - "This is an educational series to help you learn to use your metal lathe. Watch them in order for best results! Satisfaction not guaranteed, especially if you're a cranky sort of person."<br />
* Frank Hoose (Minilathe.com) has a couple of relevant Youtube playlists:<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn7ON0jGM5UbM-KZDT56MOIp Mini Lathe Operations]<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn4nGRZaVq3wTOlvZNOmdAZ2 Mini Lathe Overview]<br />
<br />
==== General Machining ====<br />
* https://www.machiningdoctor.com/ - "THE #1 MACHINING TECHNICAL HUB"<br />
<br />
==Projects==<br />
[[File:VESA mount.jpg|thumb|Machined VESA mounting plate (left) and plate from Dell monitor stand it must match (right). The translucent washer shows the size of the original center hole.]]<br />
* My first faceplate project was boring out the center hole in a VESA mounting plate to adapt it to fit onto a surplus Dell 1708FP monitor stand. The part was centered using the tailstock dead center engaging with its original center hole. I clamped the part with studs and penny washers on the driving side of two opposite corners, with cap screws in the next slot round to trap the corners under the clamping washers, then withdrew the tailstock and dead center. After machining out the bore, I used the tip of the tool, rotating the chuck by hand, to scribe a circle for laying out the bolt holes. I finished off laying out and drilling the bolt and locating holes by hand at home, fitted it to the stand, and mounted the 2nd hand LG 24" widescreen monitor.<br />
<br />
* Another ultimately unsuccessful project was fly cutting aluminum flat bar to thickness to make custom shims for the set of carbide insert tools, for the four way toolpost. The 8 mm shank tools need ~2.5 mm shim stacks, and the 6 mm shank tools need ~4.5 mm shim stacks. Ideally I'd machine single shims, but the only stock I've got handy cleans up to only 3.2mm, and some fine shimming may be needed to fine-tune the tool height.<br />
<br />
: After sorting out the clamps so they were no longer twisting the aluminum flat bar stock, and switching to the short 45° turning SCMT06204 insert tool in the four way toolpost, to improve rigidity and get a well controlled tip radius, the finish was much improved. I'm still having problems getting an even thickness and am getting approx. 0.05mm variation, I suspect due to the aluminium bar stock distorting due to internal stresses as its surface is cut away. ''ToDo: try supergluing the stock to the faceplate before clamping to further reduce chatter and stop the warping.''<br />
: Looking back on this project a year later, its fairly obvious that the thickness variation was probably due to faceplate surface runout due to the damaged spindle nose.<br />
<br />
* Raphael has been working on a steel rocket nozzle with some assistance from myself. We have set up the rough cut chunk of ~ 50mm steel bar, faced both ends (to 50mm length) and turned the OD to 49mm to clean it up. Its going to need through drilling, probably some boring, and quite a bit of detail work on the OD. It will then need to be transferred to a jig in the drill press vice to allow a pattern of angled traverse holes to be drilled with acceptable accuracy.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_Lathe_Notes&diff=17680Ian M's Lathe Notes2024-03-14T15:16:29Z<p>IanM: /* External Threading */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br />
<br />
''Currently these notes are semi-organized and non-authoritative. As I become more experienced with the RML CJ18A mini-lathe, I'm cleaning up, extending and reorganising them. Some lathe operating experience is assumed. If in doubt, '''*ASK*''' me, Andy H<sup>*</sup> , Jonathan H or another experienced minilathe operator!<br />
<br />
''* Andy H should be asked (for an authoritative answer) any questions involving RML usage policies or acquiring tooling or materials through RML.''<br />
<br />
== The Lathe ==<br />
Our Facilities page [[Facilities#Lathe|has]]:<br />
<blockquote><br />
'''Lathe'''<br />
[[File: Lathe2.jpg |200px|right | Lathe]]<br />
In the kitchen. <br />
<br />
Marked as a CJ18A Mini-Lathe from [[https://www.amadeal.co.uk/acatalog/CJ18A-Mini-Lathe-7x14-Machine-100mm-3jaw-Metric-With-Metal-Gears-AMA_LA_CJ18_M_3_MGRB.html Amadeal]]<br />
[[https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Manual]] <br />
<br />
[[Media:Lathe InductionNotes.pdf| Induction Document]]<br />
<br />
Possible upgrades:<br />
*https://www.youtube.com/watch?v=GwT-JQLbNPA<br />
<br />
''Please do not use the lathe until you have received induction'' <br />
<br clear=all><br />
</blockquote><br />
Its a Chinese import 7x14 mini-lathe. The 7x14 refers to the maximum diameter and length of work, in inches and is only a theoretical measure of the working envelope as you loose length to the chuck + any tailstock tooling, and the diameter is over the bed, not the cross-slide. See actual specifications below. <br />
<br />
Most if not all Chinese 7x10 to 7x16 mini-lathes seem to be remarkably similar (not uncommon with Chinese products due to [https://www.bunniestudios.com/blog/?p=284 Shanzhai (山寨)] )<br />
and the OEM of our Amadeal CJ18A Mini-Lathe was probably [https://www.made-in-china.com/showroom/cheap-lathe Yangzhou Realbull Machinery Co. Ltd]. Very similar lathes are also made by [https://www.siegind.com/lathe-machine.html Sieg], but their lathes tend to be slightly less sophisticated than the equivalent Realbull models.<br />
<br />
''N.B. Many Sieg parts are known to have slight but critical differences from Realbull parts, so '''DON'T''' order Sieg spares for a Realbull lathe!<br />
<br />
== Key Specifications ==<br />
Amadeal says the CJ18A Mini-Lathe is a 7x14 model with:<br />
<blockquote><br />
* Power 550 W<br />
* Distance between centres : 350 mm<br />
* Swing Over Bed: 180 mm<br />
* Swing Over Cross Slide: 110 mm<br />
* Taper: MT3<br />
* Tailstock Taper: MT2<br />
* Chuck diameter: 100 mm<br />
* Spindle Speed: 50 - 2500 rpm ''(with digital readout)''<br />
* Spindle Bore: 20 mm<br />
* Cross slide Travel: 65 mm<br />
* Range of Metric Threads: 0.5 - 2.5mm.<br />
</blockquote><br />
* The lead screw is metric, pitch 1.5 mm.<br />
* The spindle center is 90.6 mm above the flat of the bed (measured).<br />
<br />
Even though the compound and cross slide handwheels appear to be calibrated in thousandths of an inch, as ours is a metric machine, they only approximate that. One turn of a slide handwheel is 1mm advance, and they have 40 divisions, so each division is 0.025 mm, (approx. 0.984 [https://en.wikipedia.org/wiki/Thousandth_of_an_inch thou]). Similarly, the tailstock quill advances 1.25 mm per handwheel turn, which has 50 division dial, giving the same 0.025 mm divisions, but only 4 turns per 5 mm. The carriage handwheel is awkward - it moves approx. 19.2 mm per turn, and doesn't have a dial scale.<br />
<br />
== Notable Accessories ==<br />
We have:<br />
* [https://www.amadeal.co.uk/acatalog/160mm-Face-Plate-for-the-4-Mini-lathe-AMA_AC_CJ18A_FP160RB.html#SID=129 160 mm (6 1/4") Faceplate]<br />
* 100 mm (4") three jaw self-centering chuck (OEM standard) 22.5mm bore, with inside and outside jaw sets<br />
* 100 mm (4") four jaw (independent) chuck with reversible jaws (8 TPI screws)<br />
* Tailstock drill chuck (max. 13 mm dia.)<br />
* Live center for tailstock (+ OEM fixed center) <br />
* Four way Tool Post (OEM Standard)<br />
* [https://www.amadeal.co.uk/acatalog/Quick_Change_Tool_Post_for_the_mini-lathe.html Quick Change Tool Post] + 3 tool holders<br />
* [https://www.amadeal.co.uk/acatalog/Fixed-Steady-for-Mini-Lathes-AMA_AC_CJ18A_FSRB.html#SID=145 Fixed Steady Rest]<br />
* [https://www.amadeal.co.uk/acatalog/Travelling-Rest-for-Mini-Lathes-AMA_AC_CJ18_TSRB.html#SID=144 Travelling Steady Rest]<br />
<br />
''You'll find all of the above on the shelf above the lathe, with the accessories in the wooden box, apart from the steadies, which live next to it. Change gears, spare parts, and most cutting tool tips/blanks are in labelled white rectangular tins behind the lathe.''<br />
=== Measuring Tools ===<br />
We have:<br />
* Various dial indicators - the one with the adjustable magnetic base stand is the most convenient for most lathe setup work.<br />
* 25mm micrometer (in little grey case)<br />
* Grey case containing set of measurement tools including dial calipers, micrometer, steel rule (metric & inch), engineers square, and a fish-tail gauge<br />
<br />
''We currently lack''<br />
* ''A tool height setting gauge''<br />
<br />
=== Hand Tools ===<br />
Some common tools needed for normal use are kept with the lathe, in or attached to the wooden accessories box:<br />
* 2 mm Allen key - adjusting cross-slide and compound gibs<br />
* 4 mm Allen key - quick change toolholder tool clamping screws + height adjust, tightening dials<br />
* 5 mm Allen key - four way toolpost tool clamping screws, engaging/disengaging threading indicator<br />
* 6 mm Allen key - locking/unlocking quick change toolholder<br />
* 8 mm spanner - locking carriage when 8 mm socket can't be used, locking gib adjuster nuts <br />
* 13 mm spanner - changing chucks, locking steady rest jaws<br />
* Very long needle nose pliers - for grabbing swarf safely, holding one end of emery cloth safely so you can keep your fingers away from the jaws, and extricating small objects from awkward places.<br />
<br />
== Change Gears ==<br />
[[File:BC puller 1.jpg|thumb|Custom puller for B-C stub shaft]] [[File:BC puller 2.jpg|thumb|Pulling the B-C stub shaft]]<br />
See "Conquest Super Lathe" manual ([[#Manuals|below]]), section '''4.7 Change Gears''', PDF pages 28-29, but see below for mesh adjustment. The LittleMachineShop.com "Mini Lathe User’s Guide" (also below) section '''Threading''' gives a far better explanation, with pictures and diagrams, but its for a lathe with a US 1/16 inch pitch leadscrew, not a metric 1.5 mm pitch one like ours, so you *MUST* ignore all the tables in that section, replacing them with metric mini-lathe (with 1.5 mm pitch leadscrew) equivalents. <br />
<br />
We have the following tooth count gears: 20,20, 30, 35, 40,40, 45, 50,50, 60,60, 80,80<br />
which consist of the OEM power feed gears + the metric change gear set. Apart from the metal 20 tooth pinions, they are all plastic, probably Delrin if the molded in 'POM' marking can be trusted, but possibly plain Nylon 6, and are metric Module 1.<br />
<br />
If we wanted to add the capability to cut US/Imperial threads we'd need to buy additional 55, 57 and 65 tooth gears, and possibly a 21 tooth metal pinion.<br />
<br />
CGTK's [https://www.cgtk.co.uk/metalwork/calculators/changegears/minilathe?gears1=20,20,30,35,40,40,45&gears2=50,50,60,60,80,80&gears3= Change Gear Calculator] ''(link preloaded with our gear list)'' is useful if you don't want to calculate the ratios from first principles. Not all suggested combos will physically fit.<br />
<br />
* Take care *NOT* to loose the keys in the A and D shaft keyways - turn each shaft till the keyway is up before removing the gear. <br />
* The B and C gears are coupled by a hollow stub shaft (with an integral key), which is so tight in the gears it has to be pressed or driven out - I've made a puller just for this task, kept in the change gears tin.<br />
* The center of the B-C stub shaft *MUST* be lubricated where it runs on its pin on the change gear banjo bracket, with grease or heavy oil. ''Seizure of the stub shaft due to running dry is a frequent cause of catastrophic mini-lathe geartrain failures!''<br />
* Don't get oil on the change gears as it can cause plastic gears to crack. Only PTFE drylube or plastic compatible white grease should be used on their teeth. <br />
* Adjust the B-C pin position in the straight slot first to set the C to D gear mesh, tighten its nut, then swing the whole banjo about the D shaft boss to set the A to B mesh, and finally tighten the banjo clamping nut.<br />
* Check both gear meshes have running clearance by turning the chuck by hand enough to complete one full turn of the leadscrew, and by attempting to turn the intermediate gear(s) to assess backlash, If excessive resistance is felt or if there's significant backlash, readjust the gears. If you have difficulty judging the mesh, a strip of 80 gsm copier paper (approx. 0.1 mm thick) wound into the meshing teeth before tightening the stud or banjo will give appropriate clearance once removed. Once setup, check the gears run quietly under power.<br />
* If the sum of the tooth counts C+D is the same as for the ones you just removed and they were correctly meshed, you don't need to move the stub shaft pin. If A+B is <u>also</u> the same, you don't need to move the banjo. e.g. If it was set up for 16:1 reduction power feed, 1 mm (40:60 - 50:50) for M6 and 1.5 mm (e.g. 40:60:40) for M10 pitches can thus be achieved by only swapping gears. <br />
<br />
''The change gears, puller, etc. and a box spanner for the banjo nut are kept in a white rectangular tin behind the lathe.''<br />
<br />
=== Power Feed ===<br />
When used for turning with power feed, the change gears should be set for a 16:1 reduction (A:20 : B:80 - C:20 : D:80) using the pair of small metal 20 tooth pinions and the 80 tooth plastic gears (largest in set), for a feed of 0.09375 mm per turn (1.5 mm/16). Unless continuing your threading project the next session, please re-fit the 16:1 power feed set after threading so the power feed is ready for use. <br />
<br />
* *ALWAYS* leave the feed direction selector lever in its neutral (no feed) position, and the half-nuts open after use.<br />
* *ALWAYS* check the carriage lock is disengaged before engaging power feed. Unlock the carriage after use. <br />
<br />
=== Threading Dial ===<br />
The threading dial is an aid to re-engaging the half-nuts at the right moment so the tool will retrace its previous path cutting deeper, rather than offsetting axially some fraction of the thread pitch and ruining your work. Its based on the concept of the lowest integer multiples of the leadscrew and thread ''(being cut)'' pitches that exactly match, but for mechanical simplicity it only covers certain selected multiples of the leadscrew pitch.<br />
<br />
We have a choice of three pinion gears:<br />
{| class=wikitable<br />
|+ Threading dial Pinion Gears<br />
|-<br />
! Teeth !! Colour Dot !! Usable lines !! OD gear !! Dist. per turn<br />
|-<br />
| 14 || Red || 1,7 || 7.51 mm || 21 mm<br />
|-<br />
| 15 || Orange || 1,5,9 || 8.05 mm || 22.5 mm<br />
|-<br />
| 16 || Green || 1,4,7,10 || 8.37 mm || 24 mm (2 mm/div)<br />
|}<br />
They are now colour coded, with a paint dot on the gear end face ''(the only non-wear surface)''. The 16 tooth one is normally left on the lathe, but disengaged when not threading to minimise wear on the lead screw. The others are kept in the Change Gear tin.<br />
<br />
There's a threading dial 'pickup' calculator here: https://www.cgtk.co.uk/metalwork/calculators/threaddialindicator <br />
<br />
Initially select ''Lathe:'' '''Custom''', and enter the following below:<br />
* ''Units:'' '''Metric'''<br />
* ''Lead Screw Pitch (mm):'' '''1.5'''<br />
* ''Thread Dial Indicator Gear Teeth:'' '''16,15,14''' <br />
* ''Lines on Thread Dial Indicator:'' '''12''' <br />
* ''Line Marking:'' '''Every Line Numbered'''<br />
Note the teeth list is entered in reverse order so the resulting table highlights any required pinion changes.<br />
<br />
N.B. The dial is only friction clamped to the pinion by its center screw. If you have any reason to suspect it may not be properly aligned: <br />
# With the power off and the carriage unlocked, engage the feed direction lever upwards. You'll probably need to turn the chuck by hand to get it to engage.<br />
# If the threading indicator isn't already engaged, loosen the threading dial support block bolt, pivot the block to engage the pinion with the leadscrew and retighten the bolt.<br />
# Engage the half nuts, again turning the chuck by hand till they drop in. <br />
# Turn the chuck a couple of turns, top towards you to take up any backlash, then lock the carriage, taking care not to push it left while locking it.<br />
# Loosen the screw securing the dial to the pinion.<br />
# Align the '1' line of the dial with the index line, by rotating the dial clockwise, then retighten the screw.<br />
# Don't forget to disengage half-nuts and unlock the carriage!<br />
<br />
The above instructions should result in the half-nuts engaging cleanly when exactly on any valid line when threading towards the headstock. If it is required to thread away from the headstock, there will be a slight offset from the line due to backlash between the spindle gear and leadscrew, so engage slightly early.<br />
<br />
Changing the pinion:<br />
# Loosen the threading dial support block bolt and disengage from the leadscrew.<br />
# Undo dial center screw, and remove it and the dial, dropping the old pinion out the bottom.<br />
# Oil the shaft of the new pinion with a drop of light oil and insert it from below, gear end down.<br />
# Refit dial and screw.<br />
# Check the dial and pinion turn freely with minimal resistance.<br />
# Align as above.<br />
<br />
== Tailstock and Steadies ==<br />
These are mostly used to support long work ''(long with respect to its diameter)'' to improve rigidity, increasing accuracy and reducing chatter. The Tailstock quill is also used with a drill chuck for drilling.<br />
=== Tailstock ===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock base]]<br />
The tailstock can be offset to turn shallow tapers between centers. We don't currently have the accessories to turn between centers, namely <s>a MT3 dead center for the spindle, or</s> any drive dogs for the work. Also realigning the tailstock after turning a taper can be a PITA. The photo shows the tailstock adjusting screw locations ''(C - Lateral, and D - Skew)'' and the block on the baseplate they engage with. Adjustments can only take effect when the tailstock locking lever is eased to take the pressure off the baseplate. As we don't have a MT3 center, one has to turn a fresh point on a test workpiece for a rough tailstock alignment reference. Fine alignment, to avoid inadvertent taper turning, can be done by mounting a long precision ground bar between the chuck (or preferably a center in the spindle), and a dead center in the tailstock and sweeping it with a dial indicator on the carriage. Finally a test cut should be taken at either end of a bar between centers, and the diameters checked with a micrometer. Assuming the bed has previously been properly levelled and shimmed to take out twist ''(not the case at RML as we don't have it bolted down)'', any remaining difference in diameter will be double the tailstock offset, smaller at the tailstock being offset towards the front. Fine adjustment cant be achieved by jacking with the screws, its best to ease the adjusting screws, bump the tailstock into alignment then take up the screws again, checking the alignment is maintained when the tailstock is unlocked and relocked. There is no vertical adjustment, though shims can be added between the tailstock and its base.<br />
<br />
==== Tailstock Quill ====<br />
There is a metric/imperial scale on the top of the quill, read against the end of the tailstock, for depth measurement when drilling. The tailstock quill has a 1.25 mm pitch thread and a 50 division dial. Each division is therefore 0.025 mm, and it only takes 4 full turns of the handwheel to move the quill 5 mm. <br />
<br />
To eject MT2 taper tooling and centers from the tailstock, wind the quill all the way in.<br />
<br />
N.B. The quill anti-rotation pin (dog-tip setscrew + locking nut in top of tailstock near to the quill lock) is only M5. It will sheer if a large diameter drill jams in the work. Please back it out clear of its keyway if using large drills, and use alternative methods of preventing chuck rotation. To re-engage it, crank the quill out till you can see the keyway, align it with the screw and screw in the screw till it gently bottoms out, then back it off a quarter turn. Try twisting the quill to check its properly engaged, then tighten the locking nut gently to hold the screw in position clear of the bottom of the keyway.<br />
<br />
=== Steady Rests ===<br />
We have two, both with brass tips that must be kept lubricated during use.<br />
<br />
The fixed steady mounts on the ways, and is most useful when turning longer work that wont fit through the spindle bore. Adjustment is critical, and the surface the tips run on must be smooth and concentric, as any misalignment that forces the work off center will result in the work wobbling in the chuck, marring it, with a high risk of it becoming un-chucked, which can be dangerous at speed.<br />
<br />
The travelling steady mounts to the headstock side of the carriage to locally resist the deflection of thin long work, due to the cutting forces. It only has two tips, to resist climb, and deflection away from the tool, and requires readjustment after every cutting pass.<br />
<br />
== Tooling and Tool Holders ==<br />
'''Key dimensional data:'''<br />
* The quick change holders accept up to 10 mm shank tools. <br />
* The four way toolpost has 50 mm long sides, a seat width of 15 mm and can clamp tools of up to 5/8" (15.875 mm) shank ''(check this)'', but the slot base is only 10.4 mm below the spindle center so cannot be used with >10 mm shank tooling unless it has a dropped tip. Large tooling with a centered tip is also problematic as you run out of height above the shank when trying to shim to match the spindle center height. <br />
<br />
===Quick Change Toolpost===<br />
I've got the quick change toolpost and toolholders setup for mostly easy use. The three toolholders came with cantilever height setting arms which historically haven't been installed as the supplied fixing screws were too short. That's all now sorted out and a HSS RH turning tool and a HSS hand-ground grooving/parting-off tool are now mounted in two of the holders and set to height. The third is kept free for other tools. <br />
<br />
The quick change toolpost has been modified with a spring to press the dovetail clamp outwards and help stop it twisting or flopping about to ease toolholder fitting and removal. The dovetail clamp (socket headed screw on toolpost side opposite dovetail) feels a bit stiffer than before, but will take less than half a turn to go from open (with the toolholder lifting out or dropping in easily) to fully clamped. As there is so much less clearance in the open position you should no longer need to wiggle the toolholder while clamping it to get a consistent height. If the dovetail clamp ever gets misaligned, twist it straight by eye, slacken off a bit further than usual to get a toolholder on, clamp it to align the dovetail then release, reseat the toolholder and re-clamp to ensure its at its preset height. You cant adjust the height by 'jacking' with the height screw due to its offset leverage. Instead, back off the height screw and hold the toolholder at the desired height while locking the dovetail clamp, then adjust the height screw (and locking nut) to hold it there, then check it doesnt change height significantly when you unclamp and reclamp the dovetail. <br />
<br />
Unfortunately the OEM height setting screws foul the toolpost locking nut handle. Currently, if you need to swap toolposts you will have to first remove the quick-change tool holder from the post. There is enough nut handle swing to allow the quick change toolpost to be unclamped and rotated to fine set the tool angle without removing the toolholder. It also seems the mating surfaces may be slightly out of square, as if you rotate the toolpost 90° or 180°, the nut swing may be insufficient to re-clamp it without removing the toolholder to do so. Add a M10 washer under the locking nut if the handle ends up pointing in an undesirable direction! A thin M10 washer is kept with the toolpost collar for this purpose, and will shift the handle position by about a third of a turn. <br />
<br />
''ToDo: Make a taller nut of a similar pattern, to clear the height setting screws.''<br />
<br />
===Four Way Toolpost===<br />
The OEM four way toolpost is significantly more rigid than the quick change toolpost + holders because it has fewer and thicker parts and less overhang. Therefore the four way toolpost should be used when using carbide tooling. It requires shimming under the tool to set the tip height to the spindle center height - see below. The tool shanks are mostly significantly less than 15 mm wide, so need to be centered under its clamping screws, tempting as it is push the shank in for full side contact with the toolpost. If possible clamp the shank with all three screws not just two.<br />
<br />
==== Shimming ====<br />
We typically only mount up to two tools, and want maximum rigidity, so use 50 mm x 15 mm shims, (the full seat area), preferably with deburred edges and radiused corners so they aren't a hazard to the operator.<br />
<br />
We have pre-cut and marked shims of the following thicknesses: <br />
* 1x 3.23 mm, 2.42 mm, 1.56 mm, 0.32 mm, and 0.25 mm<br />
* 2x 1.00 mm, 0.77 mm, 0.12 mm, 0.11 mm, 0.10 mm and 0.05 mm<br />
* 4x 0.53 mm<br />
<br />
Our shims are mostly found materials (hence the awkward thicknesses) and are mostly a mixture of aluminium and steel, with a couple of GRP ones. The toolpost seat '''<u>must be absolutely clean</u>''' to avoid embedding debris in the aluminium or GRP shims, to get a consistent height and avoid tilting the tool - wipe it every time you change a tool! Put the thin shims at the bottom of the stack to avoid the tool shank edges creasing them. Shims are kept in a little yellow plastic box with a clear lid, near the carbide tools case.<br />
<br />
I made a tool height setting gauge (T shaped black acrylic with steps in its sides) which can be used to check the tool tip height matches the spindle center height using either the flat of the ways or the saddle as a reference. The tool tip should just fit under the lip of the appropriate step, with the T arms across the ways flats or on the saddle. It is kept in the box with the carbide insert tools.<br />
<br />
''ToDo:'' <br />
<br />
* ''Cut more shims neatly, mark them with their thickness.''<br />
* <s>''Do test cuts and start noting shim stack-ups for various tools.''</s><br />
* ''Organise shim storage!''<br />
<br />
=== HSS Tools ===<br />
[[File:Tool Bit Geometry.jpeg|thumb|Single point cutting tool geometry]]<br />
Our HSS tools are made from 8 mm square bar stock, hand-ground to tip profile in-house. See LittleMachineShop's [https://littlemachineshop.com/images/gallery/instructions/grindingtoolbits.pdf Grinding Tool Bits] notes. <br />
<br />
I've installed our usual HSS LH turning and parting off tools in two of the quick change holders and set the heights correctly. There are a couple of other HSS tools or tool blanks knocking about. Taking heavy cuts turning steel (even with good cutting oil) blunts HSS tools fairly quickly, which are time-consuming to re-sharpen nicely without a dedicated tool & cutter grinder with appropriate jigs. Its worth noting that the usual 'speeds & feeds' tables are commonly based on surface speeds expected to give a half hour (active cutting) tool life before resharpening.<br />
<br />
I touched up the LH turning tool by lapping on wet & dry (silicon carbide) paper on glass (Aka: [https://en.wikipedia.org/wiki/Scary_sharp 'Scary Sharp']) working upwards through the grits 200, 400, 600 and finally 1000, initially 'bluing' the surfaces to be lapped with a marker pen to see which areas needed taking down more. The end of the tool was significantly uneven so I touched that up freehand on the bench grinder to flatten it when it became apparent that 200 grit lapping wasn't cutting where it needed to. There was an existing micro-bevel on the leading side, which I kept. Finally I 'dubbed' the leading corner vertical edge on the 1000 grit to give it a very slight nose radius. A test cut on brass gave a very nice finish when turning.<br />
<br />
''Ian B has purchased some spare 8mm HSS tool blanks - talk to a lathe trainer if your proposed lathe work needs custom ground HSS tooling.'''<br />
<br />
=== Brazed Tungsten Carbide Tools ===<br />
Somewhat of a half-way house between hand ground HSS tooling and insert tooling with the disadvantages of both and some more besides - e.g. they are much harder to sharpen. So why do we bother? Some tool geometries would be awkward and tedious to hand grind, and Chinese import brazed carbide tooling is about half the price of similar HSS tooling, and far more readily available. Also, for space constrained tooling like boring bars, if you want carbide, for insert tooling, the size of the insert and its clamping seriously limits the minimum hole diameter you can work in. I have purchased a set of 3/8" shank brazed carbide tipped boring bars, but we currently cant sharpen them, due to lack of a diamond grinding wheel. <br />
<br />
=== Tungsten Carbide Insert Tools===<br />
Decoding ISO insert tooling part numbers: https://www.cutwel.co.uk/blog/learn-the-turning-tool-iso-code-system<br />
[[File:Carbide set.jpg|800px|thumb|left|Our set of Tungsten carbide insert lathe tools (before the new inserts were fitted)]]<br />
<br />
{| class=wikitable<br />
|+ Tools, left to right, (+ last across top):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| SSKCR0610H06 || 75° through boring || SCMT06204 || Long || 6 || 6.34 || ''4.33''<br />
|-<br />
| SSSCR0610H06 || 45° deep facing, internal chamfering || SCMT06204 || Long || 6 || 6.13 || ''4.58''<br />
|-<br />
| SWUCR0610H05 || 93° boring, deep facing || WCMT050308 || Long || 6 || 6.22 || ''4.48''<br />
|-<br />
| SWGCR0810E05 || 90° RH turning & facing || WCMT050308 || Short || 8 || 8.25 || '''2.45'''<br />
|-<br />
| SSSCR0610E06 || 45° turning, chamfering || SCMT06204 || Short || 8 || 8.75 || ''1.93''<br />
|-<br />
| SSBCR0610E06 || 75° RH turning, chamfering || SCMT06204 || Short || 8 || 8.72 || ''1.98''<br />
|-<br />
| LW0810R-04 || 60° external threading || JCL15-120 || Short || 8 || 7.44 * || ''3.28''<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || 8.23 || ''2.5 ?''<br />
|-<br />
| LN0813R-04 || 60° internal threading || JCL15-120 || Long || 7.95 || 7.44 * || ''3.28''<br />
|}<br />
<br />
{| class=wikitable<br />
|+ More Tools, (loose in tin):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || ~8.5 (not in use) ||<br />
|-<br />
| [https://www.glanze.co.uk/product/glanze-12-mm-60-degree-metric-internal-threading-tool/ Glanse SIR0012K11] || 60° internal threading bar || 11IRA60 || Long || 12 dia || ??? || ???<br />
|}<br />
''Shim stack heights in bold are tested, in italic are only calculated.'' ''Tip heights marked * are with new JCL15-120I inserts. The single remaining plain JCL15-120 insert has a slightly higher tip height.''<br />
<br />
Carbide tooling typically requires two to three times more speed than HSS and at least a couple of 'thou' depth of cut for best results.<br />
<br />
Chatter can rapidly kill carbide tooling by chipping the cutting edge. To improve rigidity and reduce the risk of chatter, the cross-slide and compound gib screws need to be well adjusted so there is minimal play in the slides, tool stick-out should be minimised, the four way toolpost should be kept over the cross-slide, and the work should be kept close to the chuck (or otherwise supported by tailstock or steady rest) to avoid excessive deflection.<br />
<br />
Thermal shock is almost instant death to carbide, and when dry cutting the insert tip can run very hot, so do not add extra cutting fluid manually during the cut. Pre-apply what you need, evenly, before starting the cut.<br />
<br />
Parting off or facing to center is high risk - if the tool tip is even slightly below center or if tool or work deflection takes it below center, the work will tend to climb over the tool tip as the cut approaches center, breaking the insert. To avoid this, the tool should be shimmed slightly above center, sufficient to allow for work and tool deflection, and unless very close to the chuck, a steady should be used. Its often preferable to part to a couple of mm dia. remaining then stop and saw through the remainder, then clean up by facing. Parting off hollow parts is much lower risk.<br />
<br />
Further investigation of the Tungsten carbide insert tool height situation is not encouraging - the so-called 'set' in question does not have a consistent tip height ''(see above table)''! In a real set, the insert seats *should* be machined allowing for the insert thickness to bring all the cutting edges to the same height with respect to the shank underside. However if you place them tip to tip on a table its easy to see there is considerable height variation, so they need to be individually shimmed (or at best, one machined shim will only be right for two or three tools). At this time we don't have dedicated shim stacks for each tool.<br />
<br />
A 2.42 mm thick shim brings the SWGCR0810E05 90° RH turning & facing tool almost exactly to center height, and good results were obtained turning 1" steel pipe. However facing 50mm steel bar stock to center found it to be slightly low, leaving a fractionally under 0.05 mm 'pip' so it needs another 0.03 mm to bring it fractionally above center. Fractionally too high is generally preferable to fractionally too low, due to tool deflection, so adding an 0.05 mm shim to the stack should produce optimum results.<br />
<br />
==== Inserts ====<br />
Ian B has purchased the spare inserts we needed in sets of five. He even was able to get the CK3 parting-off inserts which had been difficult to source!<br />
<br />
Inserts used in above tool set:<br />
* 3x SCMT06204 (square, indexable) https://www.rdgtools.co.uk/acatalog/SCMT-06-Carbide-Insert.html<br />
* 2x WCMT050308 (triangular, indexable) https://www.rdgtools.co.uk/acatalog/WCMT-05-T3-08-5XTIP-8813.html<br />
* 2x JCL15-120 (60 deg threading point) https://www.rdgtools.co.uk/acatalog/X5-JCL-15-120L-THREADING-TIPS-60-DEGREE--X5-TIP---23455.html<br />
* CK3 (parting off) https://www.rdgtools.co.uk/acatalog/CK3-CARBIDE-TIPS---PARTING--BOX-OF-5PCS--9437.html<br />
<br />
Inserts used in other tools:<br />
* 1x CK3 (as above) also missing from spare parting off tool<br />
* 1x 11IRA60 in Glanse threading bar + 1x spare<br />
<br />
=== Drills ===<br />
Various sizes of center drills are kept in a plastic bag next to the wooden accessories tray. There's also a small box of 2.5 mm center drills.<br />
<br />
We have a set of 11 TiN coated HSS drill bits from 1.5 to 8 mm, (in a cylindrical plastic index box) for tailstock drilling of brass, aluminium and non-abrasive plastics. To keep them sharp enough for the precision work we expect from the lathe, please don't use them for steel or reinforced plastics, and don't borrow them for non-lathe use. Metric and US [https://littlemachineshop.com/reference/numberdrillsize.php numbered]/[https://littlemachineshop.com/reference/letterdrillsize.php lettered] general use HSS drill bits are kept in two red metal index boxes next to the drill press.<br />
<br />
== Using the Lathe ==<br />
=== General ===<br />
Making dimensioned parts is primarily done by touching off the tool tip on a reference surface (with the lathe stopped, turning the chuck by hand), zeroing the handwheel dial, then manually counting turns and divisions. When backing off the tool its best to do so by exactly one whole turn so you don't forget the previous dial position. Stopping and measuring the work before taking the final cuts is essential if high accuracy is required. ''I've changed out the dial setscrews for flat tip ones with a tiny slug of solder under them so the dials are now friction fit on their shafts. i.e. if you hold the handle firmly taking up the backlash in the direction of cut, you can zero the dial just by grabbing and twisting it.''<br />
<br />
Carriage movement is less easy to measure as the handwheel is uncalibrated and advances an awkward bit over 19.2 mm per turn. Your options here when shoulders or other features must be exactly positioned are, in order of increasing accuracy: <br />
* Use measuring instruments, scribe the work at the desired length then work to the scribed line. Its often convenient to black the work with a permanent marker, then scribe with the tool tip, turning the chuck by hand.<br />
* for short distances, lock the carriage and use the compound, set parallel to the work<br />
* Set up a long travel dial indicator to measure carriage motion. <br />
N.B. with the leadscrew stopped, and the threading dial engaged, with its default 16 tooth gear, it will make one turn for every 24 mm of carriage movement (2 mm/div). This isn't accurate enough for positioning but is sufficient to check you aren't out by a whole mm or more.<br />
<br />
Do not allow any solvents to contact the chuck guard clear plastic as it will make the plastic brittle, or even craze it, and try to avoid melting it with the work light!<br />
<br />
===Speeds & Feeds===<br />
The surface speed of the tool relative to the work (or visa versa) is important, and best results will be achieved when it is in a tool type and material specific range. Because the surface speed is proportional to the diameter and the spindle RPM, it is usual to vary the spindle speed in inverse proportion to the diameter to get the surface speed in the desired range, and keep it there as the tool tip moves closer to the spindle axis. <br />
<br />
A cutting speed chart for HSS tooling, published by Model Engineer magazine can be found [https://www.model-engineer.co.uk/sites/7/documents/cutting%20speed%20chart.pdf [here<nowiki>]</nowiki>]. The second row is the target feed rate and the rest of the chart, apart from the diameter column is RPM.<br />
<br />
For carbide tooling cutting iron and steels, recommended speeds are generally three times higher than for HSS, but the CJ18A 2500 RPM max. spindle speed (in high gear) means you can only reach the optimum speed range for over 15 mm dia work. For small diameter work, HSS tooling may well be a better choice.<br />
<br />
An online metric speeds calculator is here: https://www.cgtk.co.uk/metalwork/calculators/cuttingspeeds <br />
<br />
How to do the maths to calculate speeds and feeds: https://www.cutwel.co.uk/blog/speeds-feeds-made-easy<br />
<br />
If you can hear the lathe 'sing' as it cuts, you are getting chatter, which invariably results in poor surface finish. Try decreasing (or possibly increasing) the spindle speed till the resonance stops. <br />
<br />
Once you have a wavy surface due to chatter, a light cut wont clean it up as the tool 'twangs' from peak to peak. You have to take a deep enough cut to get under it. For precision parts, its therefore desirable to take a trial finish cut while still 0.5 mm or so oversize, to give an opportunity to tweak the cut to get a good finish, check for taper, and that the part wont be undersize (on your test finish cut nominal diameter).<br />
<br />
=== Slide Locks ===<br />
* The carriage can be locked to the ways using the M5 hex screw through the top of the saddle to the left of the cross-slide. Double check the leadscrew is disengaged and the half-nuts open before locking it. Lock it when facing.<br />
* The cross slide can be locked by a M4 socket headed cap screw just in front of its middle gib screw. Locking the cross slide is helpful when turning very shallow conical features where the cross slide handle is in the way of the compound.<br />
* The compound slide can be locked by a M4 socket headed cap screw in line with the edge of the toolpost mount on the side with the gib adjustment screws. In normal use it should be kept backed off half a turn but it is desirable to tighten it for parting off operations to keep the resulting end faces flat.<br />
<br />
=== Compound ===<br />
The compound consists of a locking swivel and a top slide allowing cuts to be made at an angle to the axis e.g to produce bevelled or tapered features. There is a difference between US and UK usage, in the US a compound angle of 0° means the compound slide is parallel to the cross slide, but in the UK, 0° is parallel to the ways. The compound angle indicator on the CJ18A follows UK practice, 0° parallel to the ways, but it is not to be trusted, its out by a few degrees!<br />
<br />
One of the deficiencies of the CJ18A lathe is the difficulty of setting the compound angle. It is held and locked by two screws hidden under the top half of the compound slide, which must be wound back till its toolpost end is clear of the pivot point to access them. This may have to be repeated several times to snug them up enough to tap it to the desired angle, then finally tighten them. <br />
<br />
We generally keep the compound slide set approximately parallel to the ways so it can be used for short-distance longitudinal positioning without measuring. However it is unlikely to be closely parallel unless a test bar has been swept with a dial indicator on the slide, or test cuts made on a large OD workpiece and checked for taper.<br />
<br />
=== Chucks and Chuck Jaws ===<br />
==== Terminology ====<br />
* Inside jaws have steps on the outside to grip the ID of hollow work, but can also be used as outside jaws on small diameter parts (i.e. that fit through the spindle). <br />
* Outside jaws have steps on the inside to grip the OD of the work.<br />
* Universal chucks have a scroll plate with a spiral screw thread that moves all the jaws.<br />
* Independent chucks have individual adjusting screws for each jaw.<br />
<br />
==== The Chucks ====<br />
* The three jaw universal chuck can only grip near round or hexagonal work, which it centers, but its concentricity is not perfect so e.g. if you reverse the work and continue turning at the same diameter from the other end, you will see a line where the turned surfaces meet. It has separate sets of inside and outside jaws, and we normally keep the inside set installed to use as outside jaws for small diameter work.<br />
<br />
** Our jaws are individually numbered, stamped in the groove. They must be fitted in the correct sequence. The jaw slots are not clearly marked. Lowest runout for small dia. parts is achieved if you fit the jaws with #1 anticlockwise of the makers mark, then continue anticlockwise for #2 and #3.<br />
** A large strong rubber band is a great help getting all the jaws started on the scroll together - with slots #1 and #3 above the centerline and the scroll thread outer tip between #1 and #3, insert jaws #1 and #2 and put the rubber band round them to keep them in their slots. Insert jaw #3 and stretch the rubber band over it to hold it up into its slot. If the scroll was positioned correctly, all jaws should be at the same initial radius. The jaws can now be cranked in with the chuck key and they should all engage in step so they meet in the middle.<br />
:: ''Mini-lathe.com have the best instructions for [https://www.mini-lathe.com/mini_lathe/chucks/chucks.htm#Installing_Chuck_Jaws changing the jaws].'' <br />
<br />
* The four independent jaw chuck can grip most roundish or squarish work, which can either be carefully centered by the user, or deliberately gripped off-center. <br />
** Its jaws are reversible so can be swapped from inside to outside by simply cranking each jaw out and reinserting it the other way round, one at a time. DON'T move the jaws to different slots as they are likely to bind.<br />
** When setting up to face the sides of rectangular objects held crossways, it may be helpful to use both inside and outside jaw orientations, in symmetrical opposing pairs.<br />
** Its screws move their jaw 1/8" (3.125 mm) per turn<br />
<br />
* The jaws must '''never''' protrude from the chuck OD by more than one step, and for safety, its preferable they don't protrude at all, as they make the gap between the front of the bed and the chuck body an even more unforgiving meat grinder, and as the number of teeth engaged with the scroll or screw decreases, they loose strength, just when you need it the most to grip larger/heavier work. <br />
<br />
''Neither chuck is well suited to gripping tapered work safely. When seating work that doesn't quite fit through the chuck bore (which is larger than the 20mm spindle bore limit), be careful that it isn't seating on the chamfered edge of the chuck bore as it is far to easy to get the work slightly cocked so it doesn't run true.''<br />
<br />
==== Changing Chucks ====<br />
* When changing chucks, use the small grey plastic mat to protect the ways under the jaws in case you drop the chuck.<br />
* The spindle nose has two patterns of holes - the three hole pattern is for the three jaw chuck and the faceplate, and the four hole pattern is for the four jaw chuck. One hole is shared between the patterns, and is marked on the spindle nose.<br />
* To fit a chuck:<br />
** First check that the spindle nose and chuck back and recess are free of swarf, grit or other debris. Any foreign objects will tilt the chuck causing excessive runout and may mar the surfaces.<br />
** Remove the nuts and split lock washers from its studs, line its studs up with the hole pattern (preferably with the stud nearest anticlockwise to the makers mark through the marked spindle hole), fit and hold it in place with your right hand, and with your left, get the lock washer and nut on the top stud, and take up the slack.<br />
** One one nut is on, you no longer have to worry about dropping it, and can work round fitting the remaining washers and nuts, taking up the slack on each as you fit it. <br />
** Next, work round again getting them all finger tight, then tighten them gently, and finally work round fully tightening them. <br />
* Removal is the reverse of refitting. Put the washers and nuts back on the chuck's studs so they don't get lost.<br />
<br />
==== Gripping Threaded Work ====<br />
It is generally undesirable to chuck work gripped on a screw thread, as it is difficult to hold the work securely and get good concentricity while avoiding crushing the thread crests. However, if one must, one of the better ways of doing so is to wind a wire helix to fit the thread then clamp on the outside of the wire so it seats on the flanks of the thread. The wire should be mild steel or soft iron for steel parts and copper for aluminium and brass parts, single strand, round and of uniform diameter a little less than the thread pitch. It can be wound on the lathe, in reverse, by chucking a sacrificial mandrel of the same diameter and thread pitch, hooking the end of the wire round or under the jaw, against the direction of rotation, then holding the other end of the wire under tension with pliers and starting the lathe dead slow. Once wound and removed from the mandrel, the ends must be trimmed then it should be screwed on to the threaded work to provide a surface to chuck on.<br />
<br />
=== Faceplate Work ===<br />
Faceplate work is probably the most dangerous operation you can (or rather should) perform on a lathe. The working area is a large diameter spinning surface with protruding clamps to fixture the part that it is impractical to guard. Protruding clamps, studs, nuts etc. are very difficult to see at speed.<br />
<br />
'''Treat the faceplate with great respect and caution if you wish to continue to be able to count to ten on your fingers!''' <br />
<br />
The 65 mm cross-slide travel vs the 80 mm faceplate radius is a serious limitation that may require creative compound, toolpost and tool setups for larger parts, and doing full face cuts in two sections.<br />
<br />
''It is common practice to skim the faceplate to ensure it runs true. We have not (yet) done this, and wont till the spindle is in better bearings and the nose reground to minimise runout.''<br />
<br />
==== Clamping ====<br />
Open ended/sided clamps should be oriented so that cutting forces drive the work towards the clamping bolt/stud, not out from under the clamp. Minimize the protruding length of thread past the clamping nut, if necessary using sacrificial bolts or studs you can cut to length, or even using a long M8 stud for one of the faceplate mountings, so you can get a clamp nearer to the faceplate center. Double-check all clamps are secure, manually turn the faceplate to check the work and clamps clear the ways, top-slide and toolpost, and stand out of the 'line of fire' (a disc extending from the faceplate) when spinning up the work for the first time. <br />
<br />
If you need to machine close to a clamp, consider marking a safe limit circle on the faceplate and work with a marker pen to make it easier to see how close the cutting tool is to crash disaster. <br />
<br />
I strongly advise reading chapter two of Tubal Cain's book "Workholding in the Lathe" several times before your first faceplate setup, and if possible get another experienced lathe user to check your first few setups before spinning them up.<br />
<br />
==== Chuck Guard Removal ====<br />
The faceplate is too large diameter to fit under the chuck guard, but the guard has an interlock switch wqhich must be closed for the lathe to run. The guard is now fitted with wing nuts so it can be removed allowing the the interlock switch to close when using the faceplate. It *SHOULD* *ALWAYS* be refitted if a chuck is fitted, except when turning work too large to clear the guard. <br />
<br />
''The chuck guard is primarily there to make it very difficult to start the lathe without removing the chuck key and to reduce the area of large diameter spinning surface exposed. It may slow down the projectile if a chuck sheds a jaw but is unlikely to stop it. Also it serves to contain coolant spray spun off the chuck. As we don't use flood coolant this usually isn't an issue for us. As setting up for faceplate work doesn't use a chuck key, and the most hazardous zone is the face of the faceplate, with its spinning projecting clamps, with full access required for machining operations, which a guard would not cover, the consensus is that removing the guard is an acceptable risk.''<br />
<br />
=== Turning and Facing ===<br />
We are getting good results in aluminium, brass, and even steel using HSS cutting tools in quick-change tool holders, and the ~ 94 um/turn power feed. Unfortunately due to lack of rigidity in both the machine and smaller diameter parts, if you don't want the outer end to be over diameter, a light final cut and multiple 'spring' passes will probably be required.<br />
<br />
For aluminium, a sharp HSS tool and 0.5 mm (20 div) depth of cut gives good results with power feed for rapid stock removal. Its also easy maths as each cut takes ~ 1 mm off the diameter. Finish cuts should be much finer, 0.1 mm (4 div) is 'in the ballpark'.<br />
<br />
For steel, using carbide insert tooling, a 0.25 mm (10 div) depth of cut is more appropriate, and with pre-applied cutting oil, gives reasonable results with power feed if you use enough speed. The maths is not quite so easy as you are only taking 0.5 mm off the diameter per pass. Again, use finer finish cuts but try to plan your cuts so the final cut is still cutting, not smearing the surface!<br />
<br />
When facing or parting off, some skill is required to turn the cross-slide handwheel steadily to get a decent finish and to avoid shock-loading the tool tip. Increasing the spindle speed in one or more steps to keep up with the reducing diameter is advisable, but avoid speeds that cause resonances (resulting in chatter). When parting off, small through-hole parts may be caught on a thin rod chucked in the tailstock, and pre-positioned inside the work with its tip right up to the parting off position.<br />
<br />
==== Using the Steady Rests ====<br />
For the fixed steady rest, see Blondihacks' Lathe Skills #26 - How To Use a Steady Rest! [[#Youtube_Playlists_&_Videos|{below}]]<br />
<br />
Ours doesn't have ball bearing fingers, so a smooth surface on the work and adequate lubrication are essential. The thumbscrews can only tighten the fingers, so for small adjustments outwards you need to either slack off the clamping nuts or ease them slightly and use a drift against the back of the finger's slot. Once set, check the chuck still turns freely.<br />
<br />
The traveling steady rest needs to run on a machined surface, so at least for the first pass, must follow the tool, so its difficult to avoid using more compound slide overhang than is desirable. An initial surface should be cut next to the chuck or tailstock center before fitting the steady rest.<br />
<br />
Both are a PITA to fit - the fixed one has to have its clamping post inserted up through the bed, and the supplied spanner is useless near the headstock, and the travelling one's mounting holes on the saddle almost invariably need swarf picked out of them.<br />
<br />
==== Turning Between Centers ====<br />
<s>Using a MT3 to MT2 reducing sleeve, the MT2 dead center can be fitted in the spindle.</s> ''Currently the MT3 spindle taper is compromised.'' Alternatively, a soft center can be turned immediately before use in the three jaw chuck, but that must have its 60° point re-cut to concentric if the chuck is disturbed, and needs to be either large enough to bear on the chuck body, or must have a lip to bear on the end face of the jaws to take the axial thrust. Recutting the center is a PITA, as the compound angle must be set to 30° anticlockwise, then reset to a true 0° afterwards. Maybe a right-hand 30° end angle zero rake form tool is the answer, or use the carbide insert tool SSKCR0610H06 as a form tool with the toolpost rotated 15° anticlockwise.<br />
<br />
With the MT2 live center in the tailstock quill, this gives us a center either end of the work to hold it.<br />
<br />
We also need a drive dog similar to [https://littlemachineshop.com/products/product_view.php?ProductID=4473&category=1 this], and the corresponding drive post to bolt to the spindle nose. I have some 25mm bore thick wall iron pipe, which should do nicely. Lengths of the dog's straight tail and of the post TBD after I check how much the center protrudes. N.B. its recommended to tie the tail to the post to keep them in contact so they don't slam. ''Currently we will need to drive from the chuck jaws. Possibly use the exterior jaws with a short soft center gripped on the inside end and drive from the highest step.''<br />
<br />
=== Drilling ===<br />
Always start with a center drill so deflection of longer bits doesn't start the hole off-center. For larger bits (> 5 mm), first drill to the web size, then to final diameter. For a precision hole, drill slightly undersize and ream to final diameter. ''Supply your own reamers!''<br />
<br />
Caution: See note about the quill anti-rotation pin in section [[#Tailstock Quill|Tailstock Quill]] above.<br />
<br />
=== Boring ===<br />
Caution: As the spindle doesn't extend right through the headstock housing, if boring in a through hole, chips tend to fall out the back and tumble in the spindle bore till they fall into the change gears. To avoid this, one should plug the spindle bore with a wad of paper towel or rag and when cleaning up afterwards, use a rod to push it through towards the tailstock, with the chuck jaws (if fitted) wound clear of the spindle bore.<br />
<br />
A swivel bladed hole deburring tool (pale blue handle) can be found in the main room on the windowsill behind the drill press.<br />
<br />
A couple of boring jobs have been bodged with an awkwardly angled turning tool and achieving acceptable effective rake with enough clearance to reach deep enough into the hole has been problematic. I reviewed the tools we had and found none suitable for starting out in a 13mm bore, the max diameter we can (easily) drill. I therefore decided to buy a set of boring bars and make a holder for them. I had difficulty finding anything affordable under 10mm shank - the best low cost option was a [https://www.amazon.co.uk/dp/B07P5LGVBX set of nine 3/8" (9.525 mm) shank brazed carbide tipped boring bars], which would be close to the max capacity of the quick change boring bar holder - if we had one! Unfortunately this holder for our specific toolpost is difficult to find except in a toolpost bundle. Another annoyance is the variable tip height of the set, varying from 1.8 mm to 2.8 mm above the center of the shank.<br />
<br />
I therefore decided to make a boring bar holder of the [https://littlemachineshop.com/products/product_view.php?ProductID=1700 Littlemachineshop.com (USA) style] for use in the four way toolpost, as the additional rigidity will certainly help. Starting with a slightly over 50 mm length of 16 mm aluminium square bar and using the four jaw chuck , both ends were faced and an attempt was made to find its center and center drill it. It was then drilled out to ~9.8 mm after much drama due to blunt drills and drills that cut ~1mm oversize. Too big, but beggars cant be choosers as we didn't have a boring bar holder or a 3/8" reamer. Unfortunately the final hole ended up significantly off center. It was then chucked crossways and ~1 mm skimmed off its thickest side to gain clearance to allow it to be shimmed to height, then one side was slit lengthwise manually with a hacksaw.<br />
<br />
It was fitted to the for way toolpost and loaded with a booring bar, which clamped firmly. A 0.86 mm shim stack brought the tip of the largest boring bar almost spot on center height, with the difference easily accommodated by twisting the tool slightly. The three jaw chuck was then remounted, and a piece of iron pipe chucked for a test. It cuts well and leaves a decent surface finish.<br />
<br />
''The boring bar setup is a work in progress - talk to me before attempting to use them if you have a project that would benefit from boring..''<br />
<br />
ToDo: get something that can sharpen tools tipped with this grade of carbide - it needs some sort of diamond (or possibly CBN) wheel as green grit silicon carbide does little more than polish it. ''N.B. diamond wheels are rapidly eroded by grinding steel, so the supporting steel seat must be undercut with a regular grinding wheel before the diamond wheel can contact it.'' <br />
<br />
We'll also need 50 mm square sheet shims to fit under the toolpost to gain clearance in the toolpost above the tool or toolholder. A 2.4 mm shim would give us about the same above and below spindle center height, and we probably need a small selection of thinner ones.<br />
<br />
=== Thread Cutting ===<br />
The objective is to cut a thread that complies with the ISO metric thread profile. Our lathe is not currently equipped to cut non-metric threads, (with the exception of BA which have pitches based on metric threads of that era).<br />
<br />
[[File:ISO and UTS Thread Dimensions.svg|frame|center|Metric Thread Profile - from the geometry, H is ~86.6% of P]]<br />
<br />
Metric thread data - See 'Preferred Sizes' at: https://en.wikipedia.org/wiki/ISO_metric_screw_thread<br />
<br />
See "Mini Lathe User’s Guide" section '''Threading''' for general techniques *ONLY*, and above for change gears and threading dial setup.<br />
<br />
Amadeal specify the max. thread pitch as 2.5 mm. Any thread pitch greater than 1.5 nn requires the change gears to gear up. When gearing up it is desirable to distribute the ratio as evenly as possible over the two pairs of gears in the geartrain to avoid excessive tooth loading.<br />
<br />
==== External Threading ====<br />
Initially turn work to required Major Diameter, set up change gears and threading tool, touch off on the work, zero the top and cross slide dials, and do a 'scratch' pass to check the pitch. Back off the tool using the cross slide, return the carriage, and re-engage the half nuts on a valid dial line clear of the end of the thread then immediately stop the lathe, and hand turn the chuck till the tool tip is (hopefully) over the scratch to check the thread pickup. If all is good, return the carriage again, restart the lathe, bring the tool back in and start cutting your thread. <br />
<br />
Methods of doing so vary depending on the size of the thread and toughness of the metal, but straight-in plunge cutting is generally to be avoided as has the highest cutting forces, and does not reliably keep the carriage (and top-slide if set parallel to the work) loaded to avoid pitch errors due to backlash. It is common practice to set the compound angle so the cross slide is nearly parallel to the trailing flank of the threading tool tip, so all the cutting action is at the tip and leading edge. The angle should be fractionally steeper so the trailing flank rubs slightly to avoid deflection. Use a side notch on the fishtail gauge, held against the work, to set the tip exactly straight in to the work. <br />
<br />
After each pass, back the tool out using the cross slide, return the carriage to the start and bring the tool back in to exactly the same cross slide position, before advancing the compound by the depth of the next cut. The depth of cut must decrease as the thread depth increases as the width of the cut increases proportionately to the total depth, which would otherwise result in excessive cutting forces.<br />
<br />
If leaving the half-nuts engaged and reversing the lathe to return to the start of the thread for the next pass, its absolutely essential to back the tool out of the thread for the return pass as it will not follow the path of the cutting pass due to backlash in the geartrain, leadscrew mounts and half-nuts.<br />
<br />
==== Internal Threading ====<br />
''<nothing here yet>''<br />
<br />
== Cutting fluids ==<br />
=== Why bother? ===<br />
[https://youtu.be/mRuSYQ5Npek Watch this video] and contemplate what's actually happening to that thin ribbon of metal being removed. Most of the lathe's motor power is being turned into heat by internal friction in the chip being removed in the zone around the cutting edge, and surface friction at, and immediately behind the cutting edge, near-instantly heating the chip by up to several hundred degrees. Reducing the surface friction using a suitable cutting oil reduces the strain on the machine as a whole, and reduces workpiece and tool heating (and thus expansion) with consequent improvements in maximum usable feed and depth of cut, surface finish and accuracy. It also drastically increases the life of the cutting edge.<br />
<br />
=== Practicalities === <br />
We don't have a coolant system for the lathe and *really* don't want the maintenance hassles of using soluble cutting oil/coolant as if used infrequently its a PITA to keep recirculated high water content cutting fluids from going rancid and stinky, and they can also rust the ways, so even a total loss gravity feed system is problematic. Therefore if dry machining doesn't give a good enough finish, we tend to use oil applied topically, by hand to the work. <br />
<br />
* Hard brass is typically free-turning without oil, however some light oil for the final cut can improve surface finish, but with the disadvantage that it will increase loose chip buildup on the tool as hard brass typically forms short spalls or splinters rather than curly chips.<br />
<br />
* Many Aluminium alloys tend to be gummy, and Paraffin or other mineral spirits mixed with a little oil can help prevent the aluminum welding to the tool edge. WD40 will do at a pinch, but its messy to apply from a spray can.<br />
<br />
* Steel really needs *GOOD* cutting oil. Lard oil is the traditional choice for steel. If there are any objections to lard oil, we should bite the bullet and get some commercial dark high Sulphur cutting oil, but beware, many such oils use an additive package that includes lard oil.<br />
* Cast iron (except ductile) should be cut dry, as the carbon micro-inclusions self-lubricate it, and the carbide in the dust (primarily Cementite) are very abrasive, so tend to form a grinding compound if mixed with oil. <br />
<br />
I've sorted out an oil pot lid with a 1/2" brass collar soldered in to give a nice smooth sided hole, for ease of use and to minimize the risk of spills when using a brush to apply cutting oils, and got some dirt-cheap brushes. It fits Shippam's paste (and similar own-brand spread) jars and I've found several jars and ordinary lids to seal them for storage. Unfortunately it isn't the easiest to get this type of jars' lids back on square so they seal properly, and if you over-tighten them and there's a temperature change, they can be a total <expletive> to reopen. Using the rubberised handles of a large pair of pliers to grip the jar lid just above its rim is the best option, and avoids damaging the lids.<br />
<br />
''N.B. For the smaller brushes, the glue holding the bristles in is attacked by paraffin. To prevent loss of bristles, crimp the aluminium ferrule of each new brush of this type before use.''<br />
<br />
We have, in labelled jars:<br />
<br />
* Sulphurised Lard oil thinned with paraffin. Best choice for heavy cuts and threading in steel but stinky.<br />
* Lard oil thinned with paraffin. Good for steel and acceptable for softer copper alloys<br />
* Paraffin with a trace of light oil. Good for aluminium, and can help prevent squealing chatter on finish cuts in brass.<br />
<br />
I've also got some paraffin wax (in the form of a stubby candle), which can be applied lightly (under power) to brass and aluminium stock especially on the finish pass. It makes less mess than oil but unfortunately tends to build up on the tool tip, making it difficult to 'work by eye' without frequent pauses to clean the tool tip.<br />
<br />
We've also got a tin of [https://www.rocol.com/products/rtd-compound Rocol RTD cutting compound], which is a thick paste. Its highly recommended for drilling and tapping steel (in the drill press or by hand), but as a paste, is less useful for general lathe work unless thinned to a fluid consistency, e.g. with paraffin or white spirits. OTOH its certainly worth trying for high speed facing steel as it is less likely to get flung off.<br />
<br />
== Cleaning and Maintenance ==<br />
Swarf is a significant cut hazard to the operator, especially stringy swarf from cutting steel. Never touch it bare-handed - always use a tool e.g. a brush, or a hook, or needle nose pliers for grabbing long swarf.<br />
<br />
* After use, brush all swarf off the toolholder, compound and cross slide etc. ways and leadscrew. Ian B has blocked off the opening at the headstock end of the rear splashguard (to try to keep swarf out of the motor), so one must sweep the swarf towards the open tailstock end and catch it in a dustpan or similar. Preferably, also thoroughly clean out the chip tray under the lathe, but at least sweep out visible swarf.<br />
* Wipe up any cutting fluid residue and re-lubricate affected sliding surfaces with way oil.<br />
* Do not solvent clean the chuck guard, as it will make the plastic brittle, or even craze it. Water with a little detergent is permissible for cleaning it, with the guard totally removed from the lathe.<br />
<br />
Before engaging the half-nuts for power feed/threading, check the leadscrew is clean! ''Best cleaned under power, with a toothbrush.'' <br />
<br />
'''Caution:''' The traverse gears behind the carriage handwheel are in an open-backed housing and tend to become packed with swarf! Swarf buildup here will result in jerky carriage movement. Clean out as much as you can with a toothbrush ...<br />
<br />
===Lack of lubrication and/or swarf or dirt build-up can be disastrous===<br />
* If using the change gears/power feed, lack of lubrication of the B-C stub shaft center pin or either leadscrew end bearing can result in seizure and immediate destruction of one or more gears in the gear train or worse. <br />
* Small pieces of swarf can get between the saddle and ways, or into the slides degrading accuracy, possibly permanently if hard swarf scores them, or jamming them. The carriage handwheel gears behind the apron are notorious for accumulating swarf, and swarf buildup on the leadscrew can prevent the half-nuts engaging properly, resulting in scrapped work, and possibly stripped half-nuts. <br />
* Metal swarf can get into the motor (''though Ian B has modified the rear chip catcher to reduce the risk)'' or into the control box via the leadscrew, and short-circuit stuff. At best it will blow the fuse and need a strip-down to clean it out, at worst it may require a replacement [https://www.amadeal.co.uk/acatalog/Speed-Control-Circuit-Board--12amp-AMA_SP_CJ18_SCB12.html#SID=12 speed controller] ''(currently £96)'' and/or [https://www.amadeal.co.uk/acatalog/550W-motor-for-CJ18A-Mini-Lathe-467.html#SID=240 motor] ''(currently £105)'' and possibly other electrical parts. We should probably fit a [https://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C3-Mini-Lathe-Spares/C3-256-Leadscrew-Grommet-Dustproof-Cover C3-256 Leadscrew Grommet] to keep swarf out of the control box, as it tends to drop onto the 'Filter' board which is mounted horizontally, below the leadscrew.<br />
* Grit from grinding, sanding etc. forms a grinding paste with the way oil, and will rapidly wear out the ways, saddle and slides. Keep grit off at all costs e.g. by covering the ways and slides during grinding/sanding operations, and if there's any chance grit has gotten where it shouldn't, clean and re-lubricate *BEFORE* moving the carriage or slides, then move the carriage and slides, wipe down where they were with a clean paper towel and check there's no remaining traces of dirt other than clean way oil on the paper towel. If it doesn't come clean when you re-lubricate and move it again, a full strip down may be required to solvent clean and relubricate the precision sliding surfaces.<br />
* Although a metalworking lathe *can* be used to turn hardwood, wood dust and small chips are extremely pernicious, as they get everywhere, even clinging to clean surfaces, are abrasive due to their silica content, and are hygroscopic, promoting rust. An even more thorough clean-up than after using abrasives is needed, immediately afterwards. Oily wood dust and fine wood chips in significant quantities are a fire hazard, even in the trash bin.<br />
<br />
===Lubrication===<br />
See section: "Lubrication" in LittleMachineShop.com "Mini Lathe User’s Guide" [[Ian_M's_Lathe_Notes#Manuals|(below)]]. As we usually only open two nights a week, in the table on page 16, Daily lubrication becomes Weekly and Weekly becomes Monthly.<br />
<br />
===General Maintenance===<br />
* The grubscrews holding the cross-slide and compound slide dials tend to loosen due to vibration and use of the dials. Keep them snugged up, but not so tight the dials cant be set without an Allen key.<br />
<br />
* The screws holding the cross-slide nut tend to work loose due to vibration. Crank the handle to and fro through the backlash and visually check there is no movement of the screw heads in their holes. If there is, see the [[#Excessive_cross-slide_backlash|notes below]].<br />
<br />
===Removing the Carriage===<br />
Its possible to remove the carriage from the bed for cleaning etc. without dismantling it. The only stop to its motion is the righthand leadscrew bearing.<br />
<br />
Start by removing the tailstock. Crank the carriage to the tailstock end then remove the leadscrew bearing (two screws and a nyloc nut on the leadscrew end). With the half-nuts open, hold the leadscrew centered in them and crank the carriage off the end of its rack, then slide it off the end of the bed.<br />
<br />
Refitting is the reverse of removal, except (if its gibs are correctly adjusted) the carriage will be very tight on the end of the bed ways so may be difficult to work onto the ways without a stack of blocks of wood or similar to support it at exactly the right height. The righthand leadscrew bearing must be refitted with the carriage as close as possible to it and the half-nuts firmly closed to support the leadscrew at the correct height to hold it in alignment while the screws are being tightened. The nyloc nut controls leadscrew end-play. Fully tighten it then back it off slightly till the leadscrew turns freely with its change gear removed.<br />
<br />
If the Apron has been off, refit it with the screws no more than lightly finger tight and only finally tighten them after checking lead screw engagement at both ends of the carriage travel and that the rack and pinion operates smoothly over the full travel.<br />
<br />
== Issues and Annoyances ==<br />
As of September 2023 - mostly resolved, apart from the spindle bearings and runout, the lathe is in better condition than it has been for a number of years.<br />
<br />
===Four Jaw Chuck has two jaws too tight===<br />
Fixed 27/10/2023: Two of the chuck jaws were tight in their slots, making precise adjustment difficult due to lack of 'feel'. Moving the jaws round the slots showed the problem mostly followed the jaw not the slot. The grooves in the opposite sides of the affected jaws that run in the chuck slots were slightly out of true, and the rails either side of the slots were slightly too thick towards the center. Due to the difficulty of seeing the high spots, after cleaning up and deburring the jaws didn't do enough to ease them, I decided to grind the top of the rails where they were binding. Several repetitions of spotting with Engineer's blue, grinding, then diamond filing the high spots has eased them enough. I cleaned everything, greased the jaw slides and screws, and refitted the studs so the chuck is now fit for service.<br />
<br />
''N.B. Don't move the jaws to a different slot - the formerly tight jaws *must* stay in the slots furthest from the makers mark.''<br />
<br />
===Excessive Runout===<br />
Mostly fixed 24/10/2022: I ground the chuck seating surface of the spindle nose (outside lip) to under half a thou runout. This also cleaned up several burrs. It would be possible to do better, but that would need good spindle bearings, and a more rigid toolpost grinder mount.<br />
<br />
Our spindle nose was damaged years ago by a person with little mechanical aptitude (who shall remain nameless) beating it up with a hammer mushrooming the spindle nose. We are getting several thousandths runout at the end of the MT3 bore, a MT3 to MT2 reducer sleeve in it runs visibly out of true, as does the spindle nose flange. When you put a chuck on it, the runout is magnified by the distance from the spindle nose. Ideally we would replace the spindle when we change the bearings but its £52 [https://www.amadeal.co.uk/acatalog/4-Spindle-Upgrade-Real-Bull-Mini-lathe-CJ18-series-AMA_SP_CJ18_003RB.html#SID=9 from Amadeal] and money is tight. It may well require more work after the bearing upgrade. Once good bearings are in, if we can borrow a decent MT3 arbour as a reference, we should consider skimming the bore.<br />
<br />
===Spindle bearings===<br />
* The spindle bearings appear to be close to worn out. They are notably noisy when running, and there appears to be more slop in the spindle than is desirable. There is notable resonance around 600 RPM, and surface finish of end faces is often poor. We have some ideas for possible replacement/upgrade, but it requires a major teardown.<br />
<br />
: The original bearings are allegedly 6206-2RS or 6206-ZZ deep groove ball bearings - 2RS codes rubber seals both sides and ZZ codes metal shields. Although the deep groove gives reasonable ability to withstand axial loads, the bearing balls point contact means they are vulnerable to [https://en.wikipedia.org/wiki/Brinelling brinelling] due to shock loading. The jammed on three jaw chuck didn't help this, as before we skimmed the spindle nose lip, it had to be driven off using a bar through the spindle bore, shock loading the bearings every time. Also even a minor 'crash' could have brinelled them due to eccentric shock loading, and the lathe has previously been crashed badly enough to need drive gear replacement. There are also issues with the 'approved' method of spindle and bearing removal from the headstock brinelling them, even if you don't abuse the spindle nose with a hammer!<br />
<br />
: A possible replacement is 30206 tapered roller bearings. The new bearings are slightly thicker so the plastic spindle spacer (15) needs to be machined to length to get the 45 tooth spur gear that drives the change gears laterally aligned with the tumbler gears. If a temporary replacement (3D printed?) is fitted, the lathe can be run (without power feed capability) so this can be done on the lathe after fitting the new bearings. As tapered roller bearings have line contact, they are significantly more resistant to brinelling.<br />
<br />
: ''See [[Talk:Ian_M%27s_Lathe_Notes]] for notes, links etc. for this upgrade.''<br />
<br />
===Motor stuttering===<br />
* Fixed 21/09/2023: The motor was running very erratically and it was very difficult to set a speed. Several loose connections were found in the control box, mostly loose female spades to the motor controller board, but also a dry jointed braking resistor on the 'Filter' board, and an inhibit wire completely off its terminal on the forward/reverse switch, making intermittent contact. After tightening and/or remaking all affected connections, it was much improved but still not right below 300 RPM. The remaining issues were due to poor wiper contact in the speed control pot, and stripping it, cleaning the track and contact ring and re-tensioning the contacts resulted in the motor now running smoothly over the full speed range. The speed is slow to settle, and while part of that is probably the lag in the digital tach, I suspect that the KBIC motor speed controller isn't properly tuned as it was (allegedly) previously replaced.<br />
<br />
===Drive belt slipping===<br />
* Fixed 28/9/2022: During testing the motor after the above issue, it was noted that the chuck could be stalled, slipping the drive belt, with not much torque. The drive belt was determined to be loose and a bit worn, but still in acceptable condition. <br />
<br />
: Access for servicing the belt requires removing the control box ''(2 spades to ZVR switch disconnect the supply, speed sensor and motor simply unplug from the 'filter board')'', the motor cover, chuck guard switch assembly + wiring cover, the change gear 'A' (drive) shaft carrier assembly, and the tumbler gear assembly. See https://youtu.be/EkxlIz01BdA for disassembly/reassembly, though on our lathe, the speed encoder ring on the spindle prevents the belt cover from being fully removed without disturbing the spindle nuts. There is enough room to work with it loose, but still trapped by the encoder ring. Also, unlike the video, if the 'jack' screws under the headstock are correctly adjusted, and the studs aren't excessively bent, there is no need to make custom studs. <br />
<br />
: It turns out that our lathe was missing the M6 hex headed jack screws that press the motor down to resist the belt tension, and the motor had cocked out of position at a severe angle. I know Ian B had had considerable trouble adjusting it after the motor fault back in October 2022, and I believe it had been getting slowly worse ever since. The jack screws were probably mistaken for headstock fixing bolts during disassembly after the crash that resulted in the metal Hi/Lo gears being fitted, then lost. The penny washers on the studs had dished, so I turned them over and backed them up with smaller washers and switched to Nyloc nuts so they cant back off due to vibration. N.B. There is a packing washer on the motor side on one of the studs, presumably so the shaft is true to the ways. Adjusting the motor is awkward to say the least. One has to slack the stud nuts off a lot, pry under its rear end to lift it enough to be parallel to the ways, snug the stud nuts, check alignment, then set the jack screws and their lock nuts to hold it there, and finally tighten the stud nuts. <br />
<br />
: Tension: According to Sieg, it should be possible to twist the belt 90° mid span with a light finger grip. Other sources say 1/32" - 3/32" deflection mid span with light finger pressure.<br />
<br />
===Speed display blanking===<br />
* The speed display has been intermittent, blanking and flashing 8888 and 0 at certain speeds for as long as I have been using the lathe. Finally on 18/07/2022 it failed completely, with no display. I removed the display module and bench tested it - the pins are labelled 5V GND PL PE, PE is frame ground and PL is a TTL level pulse from the speed sensor - confirming that it was in good working order. My suspicions then turned to its power supply on the 'Filter' board. With both the sensor and display unplugged, the 5V rail was found to have a only a couple of volts, but the unreg DC was 17V and stable. Replacing the 78L05 5V regulator restored the 5V rail and normal operation.<br />
<br />
: ''I conclude its been failing for a while with high load current due to speeds with more lit segments causing it to drop out, resetting the speed display, causing it to blank, lowering the current enough for the regulator to recover, then the display MCU lamp tests (8888) then re-acquires the speed, repeating ad-nauseum till the speed is changed. I don't like the design as the high input voltage results in excessive dissipation.'' <br />
<br />
: ''ToDo: If it fails again, bench test display to measure its worst case current consumption, then fit an appropriate dropper resistor to reduce the 78L05 dissipation.''<br />
<br />
===Quill spinning when drilling===<br />
* The quill was tending to spin while drilling because its anti-rotation pin (a M5 dog tip setscrew) was sheered. I've removed the debris, aligned the scale with the top of the tailstock and fitted a longer M5 dog-tip setscrew to replace it, with a nut to lock it at the correct height. N.B. the pin isn't that 'meaty' so if using big drills in tough metals, to prevent shearing it, it should be backed out so the quill can be turned by hand and unwanted rotation controlled by being quick with the quill lock if it starts to spin, or even using a close fitting rod in one of the chuck key holes with plastic tube over it to protect the ways. <br />
: ''If the screw sheers again, the quill will need to be removed and the tailstock taken off the lathe so the sheered tip can be shaken out, and if the setscrew is difficult to remove it probably means the threads are mangled where it sheered. Try driving it right through with the quill out.''<br />
<br />
===Sloppy quick change toolpost locking mechanism===<br />
* Once the dovetail clamp screw was slackened, there was nothing preventing the dovetail twisting or cocking significantly, and friction with the toolholder made it tend to do so, making toolholder insertion and removal more difficult unless the clamping screw was backed off excessively. I added a compression spring around the clamp screw inside the toolpost to push the dovetail outwards so it mostly retains alignment when open, allowing toolholders to slide on or off cleanly with far less screw slackening.<br />
<br />
===Leadscrew rubbing===<br />
* The leadscrew shaft is rubbing on the insulating separator inside the control box. Unfortunately the corner of the relay on the Filter Control Board (#160) doesn't allow enough clearance. Although the friction isn't much of a problem at high reduction ratios, e.g. 16:1 power feed, it increases the stress on the change gear train, and may be problematic when threading at feeds above 1:1. ''Possibly pack out the control box mountings by a couple of mm.'' <br />
<br />
===High/Low lever backwards!===<br />
* The high-low drive gear selector behind the headstock is incorrectly labelled and differs from the manual: low gear (which we normally use) is with the lever towards the tailstock. ''I suspect that the gears in the headstock were refitted the wrong way round when it was upgraded to metal gears.''<br />
<br />
: ''ToDo: Get it reassembled the right way round during the spindle bearing upgrade!''<br />
<br />
===Carriage lock fouls top slide===<br />
* The T handscrew has been replaced with a M5 hex headed bolt, to permit access when the top slide is over it. An 1/4" drive 8mm socket is usually left on it, but needs to be removed when the full cross slide travel is needed. The small (4 jaw) chuck key is near enough 1/4" to use for it. If you need to (un)lock it while the compound is over it, you'll need an 8mm spanner. ''The [https://www.amadeal.co.uk/acatalog/Mini-Lathe-Carriage-Lock-463.html Amadeal lock screw] is in the spares tin as it was too high and fouled the compound slide.''<br />
<br />
===Tailstock locking lever loose===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock - See full image for key to screws]]<br />
* Diagnosed and fixed 10/1/2023 - In the base of the upper section of the tailstock, there are two dog tip set screws that engage with locating grooves in the counter-rotating shafts carrying the eccentric locking cams. They'd backed off, probably due to vibration. They need to be tightened till they bottom out in the groove, making sure they are '''in''' the groove, backed off half a turn so the shafts can turn easily, and locked in place. There's no facility to do so, so reassemble with weak threadlocker. Unfortunately to get to them you have to remove the tailstock base slide, which is held on by the pressure of four adjusting grub screws, which all need backing off, and one socket headed bolt from underneath so full tailstock realignment is required after reassembly, which even for a rough alignment is tedious.<br />
: <s>The tailstock locking lever is loose and can be pulled out on its axis. It works OK when fully pushed home but needs investigating. ''I tightened the grub screw as the lever was coming off its shaft, but the whole shaft pushes/pulls in and out. It works OK fully pushed in, but it seems something that is meant to retain it has failed inside the tailstock base.</s><br />
<br />
===Gear alignment issues===<br />
* Change gear alignment is poor. I've currently got a gapped washer (to clear the key) packing out the A shaft so the gears line up, but this reduces the key's engagement so is problematic due to the high loading if the gears are set up for coarser threads. <s>Also I need to turn down some penny washers to slightly less than the root diameter of the metal 20T pinions, as gear retaining washers.</s> ''The gear retaining washers for A gear and B-C stub shaft are now done, turned down to slightly under 16 mm dia. Spares in the change gear tin. ToDo: The D (leadscrew) washer requires a larger center hole, so make two more with that hole.'' <br />
<br />
===Saddle gibs loose===<br />
* Fixed 11/04/2023: I took the apron off for access (and to clean the carriage handwheel gears), and found the front sheer plate screws were completely loose. I've snugged them up some and set the opposing grub screws and got a lot of the slop out. I've re-checked the front ones, and taken up the slop in the rear ones - Unfortunately it wasn't possible to get carriage movement to have an even 'feel' over its whole travel, and its noticeably tighter near the tailstock. If light hand pressure on the side of the unlocked carriage can cause movement (with the half-nuts open), its time to readjust them again, though it should be possible to move the carriage with a firm push. <s>The saddle gibs (actually the sheer plates) were too loose, to the point that engaging a slightly stiff threading dial could cause it to self-feed, an obvious crash hazard if working near the chuck or a step in the work.</s><br />
<br />
''N.B. the lefthand front opposing grubscrew is short, (fully recessed) and unlike the others does *NOT* have a locking nut as it must clear the traverse pinion. A wrap of PTFE tape provides enough friction to keep it in place, though possibly a bit of nylon fishing line down its hole would be better.''<br />
<br />
===Excessive cross-slide backlash===<br />
* ''Fixed 21/11/2023.'' Originally, back in October 2023, The cross-slide screw had excessive backlash (nearly three turns), which increases the risk of loosing track of the cut depth when cutting steps, and during threading operations. If you ended up off by a turn too far in, a crash would be the most likely outcome.<br />
: The original excessive backlash was traced to loose cross-slide screw nut mountings. The nut has two socket headed cap screws pulling up, one either end, accessible from the top of the cross-slide, which control the tilt of the nut to take up backlash in the nut, and an opposing grub screw pressing down on the center of the nut to make it longitudinally rigid. Snugging up the grub screw reduced the backlash to 10 divisions or so, or 0.25 mm. A year later, the backlash had increased to one turn due to the cross-slide nut mounting screws working loose again.<br />
<br />
: 07/11/2023: I investigated further: It is difficult to get the cross-slide nut aligned correctly as it must be at the same height as the screw which is constrained by the bearing surfaces in the bracket. With the cross-slide almost at the front limit of its travel, I removed the screw and set the nut as level as possible and visually centered in the bore, then re-fitted the bracket and screw, then adjusted the tilt till it turned freely through the backlash. I then tilted it up at the front till some drag was felt to minimise the backlash and tightened the screws to lock it in place balancing them to maintain the same feel as I tightened them. The result was 7 divisions of backlash, acceptable but not great. During normal turning operations, the load on the nut is tension on the front screw and pressure on the grubscrew, so if it slackens again due to vibration from chatter, odds are it will be the rear screw that's loosened.<br />
<br />
: 16/11/2023 - 21/11/2023: The backlash had crept back up to 11 divisions (0.275 mm). We don't have any >14 mm brass stock (or even near that) so I tried making the shim washer out of aluminium. I was shooting for 0.24 mm but due to poor technique got 0.28 mm. No good - locked solid. I lapped it down and tried it till I got it down to 0.20 mm which gave about 3 divisions backlash - good enough, but the screw was too tight due to the shim washer not being bevelled at its outer edge resulting in it cupping in its seat. Filing a bevel round the OD and re-lapping it resulted in a 3 - 4 divisions of backlash. Its a little mushy due to the washer having been kinked removing it, so ideally a new (brass) washer should be made. <br />
<br />
* Further reduction of backlash: https://youtu.be/Wu_tI29JL2Y?t=163 <br />
: Brass tinned with Pb-free solder to form a white metal bearing surface should work at least as well as the bronze used in the video. The shim washer needs to be 10.2mm ID, with a full thickness bevel on a 14 mm OD. It isn't necessary to remove the lead screw from the cross slide, as the washer can be fitted in-situ with only the bracket removed.<br />
<br />
===3 Jaw chuck didn't mount properly===<br />
* Fixed 7/4/2023 by grinding the spindle nose lip. The three jaw chuck can now be installed and removed by hand with no hammering. A test bar in it now has only 2 thou runout (TIR) at the chuck.<br />
: <s>The three jaw chuck and the faceplate aren't seating properly on the spindle nose. Its too tight on the register diameter of the lip. This results in grossly excessive runout, and also makes this chuck and the faceplate a PITA to fit or remove.</s><br />
: ''The spindle nose had been abused with a hammer (before my time) which mushroomed it and may have brinelled its bearings. See '''Excessive Runout''' and '''Spindle bearings''' above.''<br />
<br />
== Manuals, Books and other resources ==<br />
=== Manuals ===<br />
The [https://wiki.richmondmakerlabs.uk/images/a/a3/Lathe_InductionNotes.pdf RML CJ18A Mini-Lathe Induction Notes]. Your mandatory Lathe Induction will cover most of this but its good to be able to refer back to it. Also see [[:File:Lathe Induction Bushing.pdf|Lathe Induction Bushing]], which you will make during your induction, to introduce the four key lathe skills: facing, turning, drilling, and parting off. <br />
<br />
Official [https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Amadeal CJ18A Manual], or paper copy (less complete) kept on shelf above lathe.<br />
<br />
The [https://www.chesterhobbystore.com/wp-content/uploads/2022/11/Conquest-Super-Lathe.pdf Conquest Super Lathe manual] is considerably better than the Amadeal manual and is for a near-identical machine.<br />
<br />
The [https://littlemachineshop.com/images/gallery/info/minilatheusersguide.pdf Mini Lathe User’s Guide] from LittleMachineShop.com is even more comprehensive, going into its usage in some detail, with a proper TOC, and covers both US and Metric versions of Realbull Mini-lathes. ''The only fly in the ointment is the threading section assumes a US lead screw so change gear selections and threading dial divisions will not be correct for our lathe.''<br />
<br />
[https://www.arceurotrade.co.uk/machineguides/C3-Mini-Lathe-Dismantling-and-Reassembly-Guide.pdf Sieg C3 Mini-lathe Dismantling and Reassembly Guide] "A picture story book to help you dismantle and reassemble your Sieg C3 Mini-Lathe" ''It is similar enough to ours to serve as a maintenance guide, except for the electronics, spindle drive and other headstock innards.<br />
<br />
The motor controller is a clone of a [https://acim.nidec.com/drives/kbelectronics/-/media/kbelectronics/documents/dc-drives/manuals/kbic_manual.ashx?la=en KBIC® SCR DC Motor Speed Control]<br />
<br />
=== Books ===<br />
'''Metal Turning on the Lathe''', by David A Clark, Crowood Metalworking Guides, ISBN-13: 978-1847975232 [https://www.amazon.co.uk/gp/product/B00E78RKIG Kindle Edition (£8.99)]. ''A 'free' epub can be googled for, *NOT* linked here due to dubious legality.''<br />
<br />
'''[https://archive.org/details/03screwcuttinginthelathe Screwcutting In The Lathe]''', by Martin Cleeve (a pen-name of Kenneth C Hart), Workshop Practice series #3, ISBN-13: 9780852428382<br />
<br />
'''[https://archive.org/details/15workholdinginthelathe Workholding in the Lathe]''', by 'Tubal Cain' (a pen-name of Tom Walsh), Workshop Practice series #15, Argus Books, ISBN-10: 0852429088<br />
<br />
'''[https://archive.org/details/20metalworkandmachininghintsandtips Metalwork and Machining Hints and Tips]''', by Ian Bradley, Workshop Practice series #20, ISBN-13: 9780852429471<br />
<br />
'''[https://archive.org/details/38toolandcuttersharpening Tool and Cutter Sharpening]''', by Harold Hall, Workshop Practice series #38, ISBN-13: 9781854862419<br />
<br />
'''[https://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpaperT204.pdf Cutting Fluids]''', by EC Bingham, NIST Tech. Paper No. 204, 1921<br />
<br />
=== WWW resources ===<br />
==== Mini-lathe Specific ====<br />
There's a *LOT* of mini-lathe info online. Notable sites include:<br />
* http://www.mini-lathe.com/ - A major Realbull/Sieg mini-lathe resource.<br />
* http://mikesworkshop.weebly.com/lathe-modifications.html - many mods including carriage DRO autostop, and variable speed leadscrew motor drive, cross-slide motor drive, etc. He also has a page with a bunch of accessories, toolholders etc. - http://mikesworkshop.weebly.com/lathe-accessories-and-tooling.html<br />
* http://andysmachines.weebly.com/variable-speed-controls.html - Scroll down to the 'UPDATE' section for the schematic of a very similar SCR speed control board. It also has the schematic for an earlier version of the Auxiliary Control Board (aka: 'Filter' board).<br />
* https://www.youtube.com/watch?v=WbJM9ooveo8 - A video tour of a very very similar mini-lathe. Significant differences: ours has a 4" longer bed, a quick change toolpost, a different tailstock, no DRO (apart from basic spindle speed, so skip 16:12 to 28:50 in the video), larger chucks and a carriage lock.<br />
<br />
==== Forums ====<br />
''with publicly accessible archives''<br />
* https://groups.io/g/7x12MiniLathe - Mini-lathe specific, active<br />
* https://www.hobby-machinist.com/forums/mini-lathe-mini-mill-information.220/ - active<br />
==== Youtube Playlists & Videos ====<br />
* Blondihacks: [https://www.youtube.com/playlist?list=PLY67-4BrEae9Ad91LPRIhcLJM9fO-HJyN Lathe Skills] (playlist) - "This is an educational series to help you learn to use your metal lathe. Watch them in order for best results! Satisfaction not guaranteed, especially if you're a cranky sort of person."<br />
* Frank Hoose (Minilathe.com) has a couple of relevant Youtube playlists:<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn7ON0jGM5UbM-KZDT56MOIp Mini Lathe Operations]<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn4nGRZaVq3wTOlvZNOmdAZ2 Mini Lathe Overview]<br />
<br />
==== General Machining ====<br />
* https://www.machiningdoctor.com/ - "THE #1 MACHINING TECHNICAL HUB"<br />
<br />
==Projects==<br />
[[File:VESA mount.jpg|thumb|Machined VESA mounting plate (left) and plate from Dell monitor stand it must match (right). The translucent washer shows the size of the original center hole.]]<br />
* My first faceplate project was boring out the center hole in a VESA mounting plate to adapt it to fit onto a surplus Dell 1708FP monitor stand. The part was centered using the tailstock dead center engaging with its original center hole. I clamped the part with studs and penny washers on the driving side of two opposite corners, with cap screws in the next slot round to trap the corners under the clamping washers, then withdrew the tailstock and dead center. After machining out the bore, I used the tip of the tool, rotating the chuck by hand, to scribe a circle for laying out the bolt holes. I finished off laying out and drilling the bolt and locating holes by hand at home, fitted it to the stand, and mounted the 2nd hand LG 24" widescreen monitor.<br />
<br />
* Another ultimately unsuccessful project was fly cutting aluminum flat bar to thickness to make custom shims for the set of carbide insert tools, for the four way toolpost. The 8 mm shank tools need ~2.5 mm shim stacks, and the 6 mm shank tools need ~4.5 mm shim stacks. Ideally I'd machine single shims, but the only stock I've got handy cleans up to only 3.2mm, and some fine shimming may be needed to fine-tune the tool height.<br />
<br />
: After sorting out the clamps so they were no longer twisting the aluminum flat bar stock, and switching to the short 45° turning SCMT06204 insert tool in the four way toolpost, to improve rigidity and get a well controlled tip radius, the finish was much improved. I'm still having problems getting an even thickness and am getting approx. 0.05mm variation, I suspect due to the aluminium bar stock distorting due to internal stresses as its surface is cut away. ''ToDo: try supergluing the stock to the faceplate before clamping to further reduce chatter and stop the warping.''<br />
: Looking back on this project a year later, its fairly obvious that the thickness variation was probably due to faceplate surface runout due to the damaged spindle nose.<br />
<br />
* Raphael has been working on a steel rocket nozzle with some assistance from myself. We have set up the rough cut chunk of ~ 50mm steel bar, faced both ends (to 50mm length) and turned the OD to 49mm to clean it up. Its going to need through drilling, probably some boring, and quite a bit of detail work on the OD. It will then need to be transferred to a jig in the drill press vice to allow a pattern of angled traverse holes to be drilled with acceptable accuracy.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=CncMill&diff=17643CncMill2024-02-29T15:12:30Z<p>IanM: /* Internal Notes */</p>
<hr />
<div>== Machine Overview ==<br />
<br />
3-axis OpenBuilds [https://openbuilds.com/builds/c-beam%C2%AE-machine-plate-maker.2020/ C-Beam CNC Router]. This machine is an X/Z gantry with a moving Y-table bed. The total machine travel is X 350mm, Y 280mm, Z 160mm.<br />
<br />
Control board is [https://github.com/Spark-Concepts/xPRO/wiki CNC xPRO Controller v3] from [https://web.archive.org/web/20200925063008/http://www.spark-concepts.com/cnc-xpro-controller-v3/ Spark Concepts].<br />
<br />
There are three control buttons mounted on the front side of the cabinet; resume (green), feed-hold (yellow), estop (red).<br />
<br />
The estop button will stop all the motion. If the machine was moving at the time the exact position will be lost, requiring a rehoming operation.<br />
<br />
The feed-hold button will bring the machine to a controlled stop, where it will pause.<br />
<br />
The resume button continues movement from the controlled stop of feed-hold.<br />
<br />
== Operating Instructions ==<br />
<br />
The low-level stepper controller runs GRBL and is accessed by the trailing USB cable to the side. To operate it requires a computer with some form of high-level controlling software for sending Gcode.<br />
<br />
The following is the operating sequence I [PaulEvans] found works for me.<br />
<br />
=== Computer Preparations ===<br />
<br />
The following steps need to be performed on your controlling computer (most likely a laptop) beforehand.<br />
<br />
* Prepare your Gcode shape definition file using some form of CAD/CAM software. Remember that GRBL cannot perform cutter radius compensation, so this must be done by the software generating the final Gcode output. Some useful software might include:<br />
** https://cloudconvert.com/svg-to-dxf - convert an SVG shape into DXF<br />
** https://sourceforge.net/p/dxf2gcode/wiki/Installation/ - convert a DXF shape definition into Gcode (note that at time of writing the combination of cloudconvert and dxf2gcode will get confused about inches vs. mm measurement units, requiring you to "Scale All" by a factor of 25.4 in dxf2gcode before you begin - see also https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=908543)<br />
** http://jscut.org - convert an SVG shape definition into Gcode<br />
* Obtain a copy of [https://winder.github.io/ugs_website/ Universal Gcode Sender]. There are two forms available, "Classic" and "Platform". I prefer the more featured "Platform" version.<br />
<br />
The GRBL controller now has control of spindle speed, so don't forget to include an appropriate <code>M03</code> instruction in the output to set it.<br />
<br />
=== Preparing The Machine ===<br />
<br />
Once at the machine, the following setup needs to be performed to get the machine ready for operation.<br />
<br />
# Connect the trailing USB cable to the computer you'll be running UGS from. Check that it appears as a new serial port - e.g. a new <code>/dev/ttyUSBn</code> device will appear on Linux.<br />
# Start UGS. It should detect the serial port. Configure it to "GRBL" firmware type and "115200" baud communication. Press the Connect button. UGS should now be reporting that the machine is in "Alarm" state - don't worry, that's just how GRBL powers up for some odd reason.<br />
# Send the <code>$X</code> command to reset that alarm. This will be found in the "Machine" menu under the "Actions" sub-menu item.<br />
# Send the <code>$H</code> command to start the homing cycle. This will align all the axes so that the controller knows where they are.<br />
<br />
At this point the machine is now ready to perform a milling job.<br />
<br />
=== Running A Milling Job ===<br />
<br />
Now the machine is ready to go and you have your Gcode file, you are ready to actually cut it.<br />
<br />
# Load the Gcode file into UGS (the "Browse" button in the toolbar of UGS Platform).<br />
# Mount the workpiece on the Y-bed under the machine.<br />
# Using the jog controls in UGS, move the cutting head to the appropriate "zero" reference point on your workpiece.<br />
# Once all three axes are aligned relative to the workpiece, press the "Reset Zero" button. ''Note'' be sure not to confuse it with the similarly-labelled "Return to Zero" button; which performs an entirely opposite operation!<br />
# Start the spindle controller by pressing its green "Run" button. Note that GRBL now has control of the spindle speed, so it will start at speed 0 to begin with until the G-code program instructs the spindle to begin.<br />
# Double-check the positioning is correct, and if you're happy, hit the green "Go" button in UGS to start the job.<br />
<br />
You may find it helpful to perform a "dry run" first to check that everything will be OK. Without the spindle running or the workpiece secured to the bed, the "Go" button will still make the machine move around. You can watch whether it appears to be going in the right places - the "Visualiser" window in UGS may help you to confirm this too. For extra safety against the chance of crashing the head into the bed, run this first without the endmill tool in the spindle, or at an increased Z height away from the bed. If you do run this dry-run at an increased Z height, don't forget to reset it back to the working height to do the real run.<br />
<br />
== Inventory ==<br />
<br />
A (probably incomplete) list of the milling cutters:<br />
<br />
* Drills 0.4mm - 1.2mm in 0.1mm steps<br />
* Cutters 1.5mm - 3.175mm<br />
* Endmill 2x6 (5 pcs)<br />
* Endmill 3flute 3x6 (no box)<br />
* Endmill 3flute 5x6 (no box)<br />
* Endmill 3flute 6x6 (no box)<br />
* Endmill 3flute 7x8<br />
* Endmill 3flute 8x8<br />
* Endmill 3flute 9x10<br />
* Endmill 3flute 10x10<br />
* Endmill 3flute 12x12<br />
* Rounded endmill R1x6<br />
* Rounded endmill R3x6<br />
* Rounded endmill R5x10 (2 pcs)<br />
* Ball nose endmill R10x35 ((I don't know why we have this; it's too large to fit in the spindle))<br />
* T-slot cutter 16x6<br />
<br />
== Internal Notes ==<br />
<br />
Front panel cable:<br />
<br />
{| class="wikitable"<br />
!Colour<br />
!Function<br />
|-<br />
|Black<br />
|GND<br />
|-<br />
|Red<br />
|5V (unused but may be useful for expansion)<br />
|-<br />
|Yellow<br />
|Feed hold<br />
|-<br />
|Green<br />
|Start/resume<br />
|-<br />
|White<br />
|Estop<br />
|-<br />
|Blue<br />
|Spindle PWM<br />
|}<br />
<br />
How it's all wired together (motors, control board, spindle drive)<br />
[[https://wiki.richmondmakerlabs.uk/images/4/4a/CNCRouterWiring.pdf | CNCRouterWiring.pdf]]<br />
<br />
The spindle motor is believed to be mains voltage, three phase. It is driven by a Huanyang VFD. Manual [http://www.jinlantrade.com/ebay/invertermanual.pdf here]<br />
<br />
== See Also ==<br />
<br />
* GRBL - [https://github.com/gnea/grbl]<br />
* Universal Gcode Sender - [https://winder.github.io/ugs_website]</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=CncMill&diff=17642CncMill2024-02-29T15:09:21Z<p>IanM: /* Internal Notes */</p>
<hr />
<div>== Machine Overview ==<br />
<br />
3-axis OpenBuilds [https://openbuilds.com/builds/c-beam%C2%AE-machine-plate-maker.2020/ C-Beam CNC Router]. This machine is an X/Z gantry with a moving Y-table bed. The total machine travel is X 350mm, Y 280mm, Z 160mm.<br />
<br />
Control board is [https://github.com/Spark-Concepts/xPRO/wiki CNC xPRO Controller v3] from [https://web.archive.org/web/20200925063008/http://www.spark-concepts.com/cnc-xpro-controller-v3/ Spark Concepts].<br />
<br />
There are three control buttons mounted on the front side of the cabinet; resume (green), feed-hold (yellow), estop (red).<br />
<br />
The estop button will stop all the motion. If the machine was moving at the time the exact position will be lost, requiring a rehoming operation.<br />
<br />
The feed-hold button will bring the machine to a controlled stop, where it will pause.<br />
<br />
The resume button continues movement from the controlled stop of feed-hold.<br />
<br />
== Operating Instructions ==<br />
<br />
The low-level stepper controller runs GRBL and is accessed by the trailing USB cable to the side. To operate it requires a computer with some form of high-level controlling software for sending Gcode.<br />
<br />
The following is the operating sequence I [PaulEvans] found works for me.<br />
<br />
=== Computer Preparations ===<br />
<br />
The following steps need to be performed on your controlling computer (most likely a laptop) beforehand.<br />
<br />
* Prepare your Gcode shape definition file using some form of CAD/CAM software. Remember that GRBL cannot perform cutter radius compensation, so this must be done by the software generating the final Gcode output. Some useful software might include:<br />
** https://cloudconvert.com/svg-to-dxf - convert an SVG shape into DXF<br />
** https://sourceforge.net/p/dxf2gcode/wiki/Installation/ - convert a DXF shape definition into Gcode (note that at time of writing the combination of cloudconvert and dxf2gcode will get confused about inches vs. mm measurement units, requiring you to "Scale All" by a factor of 25.4 in dxf2gcode before you begin - see also https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=908543)<br />
** http://jscut.org - convert an SVG shape definition into Gcode<br />
* Obtain a copy of [https://winder.github.io/ugs_website/ Universal Gcode Sender]. There are two forms available, "Classic" and "Platform". I prefer the more featured "Platform" version.<br />
<br />
The GRBL controller now has control of spindle speed, so don't forget to include an appropriate <code>M03</code> instruction in the output to set it.<br />
<br />
=== Preparing The Machine ===<br />
<br />
Once at the machine, the following setup needs to be performed to get the machine ready for operation.<br />
<br />
# Connect the trailing USB cable to the computer you'll be running UGS from. Check that it appears as a new serial port - e.g. a new <code>/dev/ttyUSBn</code> device will appear on Linux.<br />
# Start UGS. It should detect the serial port. Configure it to "GRBL" firmware type and "115200" baud communication. Press the Connect button. UGS should now be reporting that the machine is in "Alarm" state - don't worry, that's just how GRBL powers up for some odd reason.<br />
# Send the <code>$X</code> command to reset that alarm. This will be found in the "Machine" menu under the "Actions" sub-menu item.<br />
# Send the <code>$H</code> command to start the homing cycle. This will align all the axes so that the controller knows where they are.<br />
<br />
At this point the machine is now ready to perform a milling job.<br />
<br />
=== Running A Milling Job ===<br />
<br />
Now the machine is ready to go and you have your Gcode file, you are ready to actually cut it.<br />
<br />
# Load the Gcode file into UGS (the "Browse" button in the toolbar of UGS Platform).<br />
# Mount the workpiece on the Y-bed under the machine.<br />
# Using the jog controls in UGS, move the cutting head to the appropriate "zero" reference point on your workpiece.<br />
# Once all three axes are aligned relative to the workpiece, press the "Reset Zero" button. ''Note'' be sure not to confuse it with the similarly-labelled "Return to Zero" button; which performs an entirely opposite operation!<br />
# Start the spindle controller by pressing its green "Run" button. Note that GRBL now has control of the spindle speed, so it will start at speed 0 to begin with until the G-code program instructs the spindle to begin.<br />
# Double-check the positioning is correct, and if you're happy, hit the green "Go" button in UGS to start the job.<br />
<br />
You may find it helpful to perform a "dry run" first to check that everything will be OK. Without the spindle running or the workpiece secured to the bed, the "Go" button will still make the machine move around. You can watch whether it appears to be going in the right places - the "Visualiser" window in UGS may help you to confirm this too. For extra safety against the chance of crashing the head into the bed, run this first without the endmill tool in the spindle, or at an increased Z height away from the bed. If you do run this dry-run at an increased Z height, don't forget to reset it back to the working height to do the real run.<br />
<br />
== Inventory ==<br />
<br />
A (probably incomplete) list of the milling cutters:<br />
<br />
* Drills 0.4mm - 1.2mm in 0.1mm steps<br />
* Cutters 1.5mm - 3.175mm<br />
* Endmill 2x6 (5 pcs)<br />
* Endmill 3flute 3x6 (no box)<br />
* Endmill 3flute 5x6 (no box)<br />
* Endmill 3flute 6x6 (no box)<br />
* Endmill 3flute 7x8<br />
* Endmill 3flute 8x8<br />
* Endmill 3flute 9x10<br />
* Endmill 3flute 10x10<br />
* Endmill 3flute 12x12<br />
* Rounded endmill R1x6<br />
* Rounded endmill R3x6<br />
* Rounded endmill R5x10 (2 pcs)<br />
* Ball nose endmill R10x35 ((I don't know why we have this; it's too large to fit in the spindle))<br />
* T-slot cutter 16x6<br />
<br />
== Internal Notes ==<br />
<br />
Front panel cable:<br />
<br />
{| class="wikitable"<br />
!Colour<br />
!Function<br />
|-<br />
|Black<br />
|GND<br />
|-<br />
|Red<br />
|5V (unused but may be useful for expansion)<br />
|-<br />
|Yellow<br />
|Feed hold<br />
|-<br />
|Green<br />
|Start/resume<br />
|-<br />
|White<br />
|Estop<br />
|-<br />
|Blue<br />
|Spindle PWM<br />
|}<br />
<br />
How it's all wired together (motors, control board, spindle drive)<br />
[[https://wiki.richmondmakerlabs.uk/images/4/4a/CNCRouterWiring.pdf | CNCRouterWiring.pdf]]<br />
<br />
The spindle motor is believed to be mains voltage, three phase, probably star-wired. It is driven by a Huanyang VFD. Manual [http://www.jinlantrade.com/ebay/invertermanual.pdf here]<br />
<br />
== See Also ==<br />
<br />
* GRBL - [https://github.com/gnea/grbl]<br />
* Universal Gcode Sender - [https://winder.github.io/ugs_website]</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=CncMill&diff=17641CncMill2024-02-29T13:39:26Z<p>IanM: /* Machine Overview */</p>
<hr />
<div>== Machine Overview ==<br />
<br />
3-axis OpenBuilds [https://openbuilds.com/builds/c-beam%C2%AE-machine-plate-maker.2020/ C-Beam CNC Router]. This machine is an X/Z gantry with a moving Y-table bed. The total machine travel is X 350mm, Y 280mm, Z 160mm.<br />
<br />
Control board is [https://github.com/Spark-Concepts/xPRO/wiki CNC xPRO Controller v3] from [https://web.archive.org/web/20200925063008/http://www.spark-concepts.com/cnc-xpro-controller-v3/ Spark Concepts].<br />
<br />
There are three control buttons mounted on the front side of the cabinet; resume (green), feed-hold (yellow), estop (red).<br />
<br />
The estop button will stop all the motion. If the machine was moving at the time the exact position will be lost, requiring a rehoming operation.<br />
<br />
The feed-hold button will bring the machine to a controlled stop, where it will pause.<br />
<br />
The resume button continues movement from the controlled stop of feed-hold.<br />
<br />
== Operating Instructions ==<br />
<br />
The low-level stepper controller runs GRBL and is accessed by the trailing USB cable to the side. To operate it requires a computer with some form of high-level controlling software for sending Gcode.<br />
<br />
The following is the operating sequence I [PaulEvans] found works for me.<br />
<br />
=== Computer Preparations ===<br />
<br />
The following steps need to be performed on your controlling computer (most likely a laptop) beforehand.<br />
<br />
* Prepare your Gcode shape definition file using some form of CAD/CAM software. Remember that GRBL cannot perform cutter radius compensation, so this must be done by the software generating the final Gcode output. Some useful software might include:<br />
** https://cloudconvert.com/svg-to-dxf - convert an SVG shape into DXF<br />
** https://sourceforge.net/p/dxf2gcode/wiki/Installation/ - convert a DXF shape definition into Gcode (note that at time of writing the combination of cloudconvert and dxf2gcode will get confused about inches vs. mm measurement units, requiring you to "Scale All" by a factor of 25.4 in dxf2gcode before you begin - see also https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=908543)<br />
** http://jscut.org - convert an SVG shape definition into Gcode<br />
* Obtain a copy of [https://winder.github.io/ugs_website/ Universal Gcode Sender]. There are two forms available, "Classic" and "Platform". I prefer the more featured "Platform" version.<br />
<br />
The GRBL controller now has control of spindle speed, so don't forget to include an appropriate <code>M03</code> instruction in the output to set it.<br />
<br />
=== Preparing The Machine ===<br />
<br />
Once at the machine, the following setup needs to be performed to get the machine ready for operation.<br />
<br />
# Connect the trailing USB cable to the computer you'll be running UGS from. Check that it appears as a new serial port - e.g. a new <code>/dev/ttyUSBn</code> device will appear on Linux.<br />
# Start UGS. It should detect the serial port. Configure it to "GRBL" firmware type and "115200" baud communication. Press the Connect button. UGS should now be reporting that the machine is in "Alarm" state - don't worry, that's just how GRBL powers up for some odd reason.<br />
# Send the <code>$X</code> command to reset that alarm. This will be found in the "Machine" menu under the "Actions" sub-menu item.<br />
# Send the <code>$H</code> command to start the homing cycle. This will align all the axes so that the controller knows where they are.<br />
<br />
At this point the machine is now ready to perform a milling job.<br />
<br />
=== Running A Milling Job ===<br />
<br />
Now the machine is ready to go and you have your Gcode file, you are ready to actually cut it.<br />
<br />
# Load the Gcode file into UGS (the "Browse" button in the toolbar of UGS Platform).<br />
# Mount the workpiece on the Y-bed under the machine.<br />
# Using the jog controls in UGS, move the cutting head to the appropriate "zero" reference point on your workpiece.<br />
# Once all three axes are aligned relative to the workpiece, press the "Reset Zero" button. ''Note'' be sure not to confuse it with the similarly-labelled "Return to Zero" button; which performs an entirely opposite operation!<br />
# Start the spindle controller by pressing its green "Run" button. Note that GRBL now has control of the spindle speed, so it will start at speed 0 to begin with until the G-code program instructs the spindle to begin.<br />
# Double-check the positioning is correct, and if you're happy, hit the green "Go" button in UGS to start the job.<br />
<br />
You may find it helpful to perform a "dry run" first to check that everything will be OK. Without the spindle running or the workpiece secured to the bed, the "Go" button will still make the machine move around. You can watch whether it appears to be going in the right places - the "Visualiser" window in UGS may help you to confirm this too. For extra safety against the chance of crashing the head into the bed, run this first without the endmill tool in the spindle, or at an increased Z height away from the bed. If you do run this dry-run at an increased Z height, don't forget to reset it back to the working height to do the real run.<br />
<br />
== Inventory ==<br />
<br />
A (probably incomplete) list of the milling cutters:<br />
<br />
* Drills 0.4mm - 1.2mm in 0.1mm steps<br />
* Cutters 1.5mm - 3.175mm<br />
* Endmill 2x6 (5 pcs)<br />
* Endmill 3flute 3x6 (no box)<br />
* Endmill 3flute 5x6 (no box)<br />
* Endmill 3flute 6x6 (no box)<br />
* Endmill 3flute 7x8<br />
* Endmill 3flute 8x8<br />
* Endmill 3flute 9x10<br />
* Endmill 3flute 10x10<br />
* Endmill 3flute 12x12<br />
* Rounded endmill R1x6<br />
* Rounded endmill R3x6<br />
* Rounded endmill R5x10 (2 pcs)<br />
* Ball nose endmill R10x35 ((I don't know why we have this; it's too large to fit in the spindle))<br />
* T-slot cutter 16x6<br />
<br />
== Internal Notes ==<br />
<br />
Front panel cable:<br />
<br />
{| class="wikitable"<br />
!Colour<br />
!Function<br />
|-<br />
|Black<br />
|GND<br />
|-<br />
|Red<br />
|5V (unused but may be useful for expansion)<br />
|-<br />
|Yellow<br />
|Feed hold<br />
|-<br />
|Green<br />
|Start/resume<br />
|-<br />
|White<br />
|Estop<br />
|-<br />
|Blue<br />
|Spindle PWM<br />
|}<br />
<br />
How it's all wired together (motors, control board, spindle drive)<br />
[[https://wiki.richmondmakerlabs.uk/images/4/4a/CNCRouterWiring.pdf | CNCRouterWiring.pdf]]<br />
<br />
== See Also ==<br />
<br />
* GRBL - [https://github.com/gnea/grbl]<br />
* Universal Gcode Sender - [https://winder.github.io/ugs_website]</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Facilities&diff=17640Facilities2024-02-28T18:35:54Z<p>IanM: /* CNC Mill */</p>
<hr />
<div><!--<br />
New facilites page by Andy (beardedfool)<br />
Problem:<br />
I found RML through the wiki (only discovering the www page after I had visited) and couldn't find what I was looking for easily - what toys you had there. <br />
<br />
e.g. There's an inventory page and a facilities page which seem to duplicate information - but neither link to useful other pages e.g. the laser cutter page.<br />
<br />
Solution<br />
I've had a go at clearing them up. I'd like to 'give back' by creating some instructions for equipment as people are kind enough to show me them (e.g. lathe, laser cutter, CNC, 3D printing)<br />
Tidying these pages is the first step - then I can use this page as a jump off for these instructions.<br />
<br />
As it's a bit presumptious - I've largely kept the content the same at the moment, apart from minor edits for clarity. I suspect it's still not wholly accurate in terms of assets you have, other pages that should be linked or out of date content but hopefully a start<br />
<br />
Testing<br />
As I don't have editing rights to the wiki I put it into https://www.mediawiki.org/wiki/Project:Sandbox by edit source' button and looks largely right but problems with images likely - kept most the <br clear=all> tags in but may be a better way https://en.wikipedia.org/wiki/Template_talk:Clear <br />
<br />
Questions/ next steps<br />
Create repository on your github for this? May be an unwanted layer of abstraction, but as it's code. <br />
<br />
Contact people about Asset database (Dan), Laser Cutter materials (Kim) and other 3D printers (Paul B)<br />
<br />
Add to wiki LHS navigation menu as Facilities; redirect inventory page to this - #REDIRECT [[Facilities]]<br />
<br />
Create other instructions over time<br />
<br />
<br />
Code starts... --><br />
<br />
=Audio Visual=<br />
===Bluetooth-enabled Stereo===<br />
How to use<br />
# Turn on the power switch connected to the stereo to the right of the double-doors. <br />
# Press "VIDEO/AUX" on the stereo input dial (in the middle) to connect it to the Bluetooth receiver. <br />
# On your Bluetooth-enabled smartphone or laptop device, go into your Bluetooth preferences and search for devices. You will see "Belkin HD" as one of the available devices. Pair it with your device and start playing music/podcasts/Internet streams. <br />
# If you do not see "Belkin HD" then power cycle the Belkin device and search again.<br />
<!--<br />
===Plasma screen===<br />
[[File: PlasmaScreen.jpg |200px|right | Plasma Screen]]<br />
Huge screen. Can't miss it. HDMI, DVI, ... sound is the only thing that does not work. <br />
More information [[Panasonic_TH-65PF12EK|here]]<br />
--><br />
<br clear=all><br />
<br />
=CAD - Computer aided design=<br />
<br />
===3D printing===<br />
[[File: 3DPrinter.jpg |200px|right | 3D printer]]<br />
Some basics on 3D printing [[3dprinting-basics|here]]<br />
<!--<br />
====BIQU Magician====<br />
* A good machine as an introduction to 3D printers for new-comers. Works well with minimal changes of settings. More here<br />
====[http://www.deltamaker.com/ DeltaMaker] 3D printer====<br />
it is connected to the network via [https://octoprint.org/ octoprint]. <br />
* When you are at little house point your web browser to http://deltamaker.rml<br />
* Login to octoprint with <br />
**user:rml <br />
**password: rml<br />
* ssh <br />
** pi<br />
** deltamaker<br />
--><br />
====Geeetech I3 pro B====<br />
[[Geetech_I3_Pro_B| here]]<br />
<br />
====Zombie Printer====<br />
A machine so modified it got a new name<br />
* Dedicated page [[The_Zombie_Printer|here]]<br />
,!--<br />
====Geetech Dual Extruder====<br />
Currently only one extruder working<br />
* GT2560 board<br />
====Formlabs 1+ resin printer====<br />
[[https://wiki.richmondmakerlabs.uk/index.php/Formlabs_3d_printer here]]<br />
====Phrozen resin printer====<br />
Web GUI, IP is shown when machine is started. Has a slicer built in<br />
--><br />
===CNC Mill===<br />
[[File: CNCRouter.jpg |200px|right | CNC machine]]<br />
CNC Mill - OpenBuilds [https://openbuilds.com/builds/c-beam%C2%AE-machine-plate-maker.2020/ C-Beam CNC Router] <br />
In the cloakroom<br />
<br />
''Please do not use the CNC Mill until you have received induction''<br />
* Instructions on use from Leo [[CncMill|here]] and Nick [https://web.archive.org/web/20210928032955/https://ndevenish.com/2017/01/26/cnc-update.html here (Internet Archive)]<br />
<br clear=all><br />
<br />
===Laser cutter===<br />
[[File: LaserCutter.jpg |200px|right | Laser Cutter]]<br />
<br />
Privately owned Laser cutter (60W) can be used periodically for prototyping. <br />
<br />
[[Laser_cutter|Has it's own page here]]<br />
<br />
''Please do not use the laser cutter until you have received induction''<br />
<br />
=Crafts=<br />
===Sewing machine===<br />
There is a mini sewing machine from John Lewis on loan from Andres. Feel free to use when ever. It is kept in its box on the gray shelves next to the kitchen. <br />
Follow this video for [https://www.youtube.com/watch?v=eFABAbK4Beo threading] and first steps! <br clear=all><br />
<br />
=Electronics workbench=<br />
[[File:Electronics Bench 2022.jpeg |200px|right |Electronics Bench]]<br />
[[File:20221206 Electronics.jpg|200px|right |Electronics Bench in use]]<br />
See our [[Electronics]] page for notes, tutorial links, etc.<br />
===General===<br />
* Various hand tools, test equipment, wiring, connectors, resistors, capacitors, LEDs and other assorted components<br />
* UV exposure box<br />
* Magnifying lamp<br />
* 'Helping Hands'<br />
** Two positionable clips to hold wires, components and small assemblies<br />
** Magnifier<br />
* Tiltable plastic jawed vice<br />
** for holding small to medium PCBs and small assemblies<br />
** ''Do *NOT* use for assembling IDC cables or forcing a fit - grab a drill press vice from the engineering bench for that!''<br />
<br />
===Soldering/Desoldering===<br />
* Weller WS80 temperature controlled soldering station<br />
** with WSP80 iron (24V, 80W)<br />
** takes [https://docs.rs-online.com/9b2b/0900766b803f878a.pdf LT series tips]<br />
** [https://www.pkelektronik.com/media/downloads/w/e/weller%20loetstation%20ws%2080.pdf Operating Instructions] - Controls/Connections layout on pages 2 & 3, English instructions start at page 23<br />
* <s>Maplin (Precision Gold) temperature controlled soldering station</s> - ''U/S as of 5/10/2022''<br />
** with 24V, 48W iron - ''element failed''<br />
** Chinese OEM: [http://www.china-zhongdi.com/product/36.html Zongdi ZD-937] <br />
** UK source for spares: [https://uk.farnell.com/duratool/d00675/soldering-station-48w-230v-uk/dp/1498364 Duratool D00675 @Farnell]<br />
* Power+ 8000 series SMD Rework Station<br />
** A 'knockoff' of a [http://yihua-soldering.com/product-1-1-1-2in1-hot-air-rework-station-en/147633/ Yihua 852D+] - [https://www.manualslib.com/manual/2488638/Yihua-706-Series.html#product-852%20Series 852D+ Manual]<br />
** Variable temperature and flow hot air tool - ''Missing its hot air nozzles apart from the 6 mm one fitted.''<br />
** 50W temperature controlled soldering iron - Takes HAKKO 900 series tips. <br />
*** The iron is a Yihua 907A clone, five pin GX16 connector, male on the station, female on the iron, [[:File:Yihua GX16.png|Yihua pinout]]. The iron has an A1322 clone element nom. 24V 50W. Tips should be 6 - 6.5 mm OD, and nom. 4 mm ID.<br />
<br />
:: ''N.B. Tips must be a good close fit on the ceramic element, but not excessively tight. Many clone tips are too loose and will need a sleeve to function. If the tip is too tight there is a high risk of breaking the element.'' <br />
<br />
:: ''Yihua knockoffs are not known for their electrical safety. A test sticker indicates it passed in 2018 (probably PAT testing) and the hot air nozzle is grounded, but we should check if there is a reliable ground at the soldering iron socket. See [https://www.eevblog.com/forum/reviews/w-e-p-yihua-852d-combined-hot-air-station-and-soldering-iron/ 852D topic @EEVblog]''<br />
<br />
* BGA re-balling station - [https://www.youtube.com/watch?v=fNxXn32L74o YouTube demo]<br />
** Uses same Yihua 907A type iron as the SMD rework station. <br />
* Solder sucker station - see: [http://www.ameritronics.com/digital_desolddering_de-soldering_stations_tools.htm HOW TO DESOLDER THROUGH HOLE COMPONENTS, CONNECTORS & CHIPS?]<br />
<br />
===Bench Power Supply===<br />
* Thurlby PL320 Bench Power Supply<br />
** dual channel 0-30V, 2A<br />
**[http://www.av.it.pt/medidas/Data/Manuais%20&%20Tutoriais/05%20-%20Programable%20Power%20Supplay%20PL330DP/PL%20Series%20Instruction%20Manual%20-%20Iss%2012.pdf PL series instruction Manual]<br />
<br />
===Pulse Generator===<br />
* AIM & THURLBY THANDAR INSTRUMENTS TGP110 10Mhz Pulse Generator<br />
** [http://www.farnell.com/datasheets/1734341.pdf?_ga=2.28719740.1736682119.1560968692-1735494415.1560968692 datasheet]<br />
<br />
===Oscilloscope===<br />
*Rigol DS1104Z<br />
**4 channel 50MHz Digital Oscilloscope<br />
**[https://www.batronix.com/pdf/Rigol/UserGuide/DS1000Z_UserGuide_EN.pdf Manual]<br />
<br />
===Multimeters===<br />
* [https://dam-assets.fluke.com/s3fs-public/75_77___omeng0900.pdf Fluke 77] DMM (grey, in brown rubber bumper)<br />
** ''N.B. Rotary mode switch detent is very weak, so carefully align pointer with desired mode indication before use.''<br />
* [https://dam-assets.fluke.com/s3fs-public/7x2x____iseng0200.pdf Fluke 77 III] DMM (grey/yellow)<br />
* Various cheap small DMMs - See Big Clive's [https://youtu.be/-QDW0LRQVrY video review/tutorial] <br />
** ''CAUTION: Do *NOT* use the cheap DMMs on live mains circuits''<br />
<br />
''Please carefully check the red test lead is *NOT* plugged in the 300mA or 10A (current) sockets before making voltage measurements, as the Fluke current range fuses are expensive to replace!''<br />
<br />
=== PC/Mac hosted tools ===<br />
* [https://en.wikipedia.org/wiki/LTspice LTspice XVII] circuit simulator is installed on the all-in-one Mac next to the electronics bench. ''<s>(PC version running under WineBottler)</s>''<br />
* Arduino IDE (v1.8.19) is installed on the same Mac.<br />
* An eight channel USB logic analyser ''(Salae Logic 8 clone)'' is available ''(bin on the electronics shelves at the end over the wood store)'', and the [https://sigrok.org/wiki/Main_Page Sigrok] software to support it is installed on the Mac.<br />
<br />
=Makers Equipment=<br />
* Arduino Starter kit<br />
* Funduino kit with loads of sensors<br />
* Raspberry Pi (with Pi Camera)<br />
<br clear=all><br />
<br />
=Engineering/ Woodwork=<br />
<br />
===Bench drill===<br />
*Silverline 262212 Drill press<br />
**Chuck Capacity 13mm<br />
** 350W<br />
See our [[Drill press]] page for general instructions and its [https://www.silverlinetools.com/en-GB/Product/ProductDetail?ModelName=262212 Manual] for specifics.<br />
<br />
<br clear=all><br />
<br />
===Lathe===<br />
[[File: Lathe2.jpg |200px|right | Lathe]]<br />
In the kitchen. <br />
<br />
Marked as a CJ18A Mini-Lathe from [[https://www.amadeal.co.uk/acatalog/CJ18A-Mini-Lathe-7x14-Machine-100mm-3jaw-Metric-With-Metal-Gears-AMA_LA_CJ18_M_3_MGRB.html Amadeal]]<br />
[[https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Manual]]<br />
<br />
[[Media:Lathe InductionNotes.pdf| Induction Document]]<br />
<br />
Possible upgrades:<br />
*https://www.youtube.com/watch?v=GwT-JQLbNPA<br />
<br />
''Please do not use the lathe until you have received induction'' <br />
<br />
[[User:IanM|IanM]] has written some more detailed [[Ian M's Lathe Notes|notes on using the RML Lathe]].<br />
<br />
===Bandsaw===<br />
N B This is out of action and in need of replacement<br />
<br />
*Nutool HBS230 230mm Two Wheel Bandsaw <br />
**230W <br />
**Similar [https://www.workshopping.co.uk/files/09681ins.pdf Manual]<br />
*Replacement parts:<br />
**Got some tyres from [www.Solenttools.co.uk solent tools]<br />
**Ian got a new blade from ???<br />
<br />
===Jigsaw===<br />
Bosch PST 700E 500W Jigsaw<br />
[https://www.bosch-diy.com/gb/en/p/pst-700-e-06033a0000-v100024162 Manual]<br />
<br />
===Mitresaw===<br />
Erbauer ERB255GS 2000W 10" Sliding compound mitre saw with laser<br />
<br />
===Router (handheld)===<br />
Black & Decker KW850E 1100W </br><br />
[http://2helpu.com/PDMSDocuments/EU/Docs//docpdf/kw850e_uk.pdf here Manual]<br />
<br />
===Planer (handheld)===<br />
Ryobi EPN-6082 600W </br><br />
[http://www.free-instruction-manuals.com/pdf/p41861.pdf Manual]</br><br />
<br />
===Bench Grinder===<br />
Clarke Metalworker CBG 6RZ </br><br />
[https://www.clarkeservice.co.uk/product_manuals/metalworking_bench_grinders.shtml Manual]<br />
<br />
===Belt Sander===<br />
N.B. We no longer have this as the motor broke. Kept as a reminder we need one and for safety warning<br />
*KOBE KBE2714140K<br />
*[https://www.manualslib.com/manual/1229237/Kobe-Sbd370.html Manual] and [https://cromindo.com/uploads/product_info/KBE/271/KBE2714140K_5.pdf here]<br />
**Safety: Please don't use the dust extraction when sanding metal - hot sparks, wood chippings and lots of air equals fire<br />
<br />
===Compressor===<br />
[[File: Compressor.jpg |200px|right | Compressor]]<br />
Mains-powered air compressor with a long air pipe and a few tools, including paint sprayer. <br />
<br clear=all><br />
* Ratchet tap handles<br />
* 0 - 10 BA tap & die set (imperial)<br />
* Broken bolt extractor set (Easy Outs)<br />
<br clear=all><br />
<br />
=General purpose=<br />
* Ultrasonic cleaner (6.5L) - Tank internal dimension: 300 (L) x 150 (D) x 150 (H) mm<br />
* Small screw driver set with prying tool for mobile phone disassembly<br />
* Spanner set 6mm to 26mm - ''In cloakroom, on bathroom door''<br />
* Hot glue gun<br />
* Dremel 200 rotary Multi-Tool (two speed - 15K/35K RPM no load) - [https://www.dremel.com/storage/en-gb/dremel-200-series-774-original-pdf-19921-en-gb.pdf Instructions]<br />
** Flexible shaft<br />
** 3rd party sets of bits and accessories <br />
::''The green box bits & accessories set is the most complete. The other one is overspill + half worn-out bits. The flexible shaft is now kept off the tool as its rarely used. Please try not to loose the little shaft coupling nut from the tool end of the flexible shaft! The Dremel and its attachments and accessories live in the large translucent plastic crate on the grey shelves next to the cloakroom door.''<br />
* [https://uk.rs-online.com/web/p/multitools/4722782 RS Pro Mini Drill] - 12V drill (max. 17K RPM no load) & Variable speed PSU<br />
** with 3.2 mm (1/8") capacity 3 jaw chuck<br />
** uses Dremel bits, but not fixed accessories<br />
::''Lives with the Dremel in the large translucent plastic crate on the grey shelves next to the cloakroom door. Chuck key is taped to its 12V power cord. A better choice than the Dremel for precision drilling.''<br />
* Set of files (round, square, triangular, flat, half round) - ''On side wall next to Woodworking bench''<br />
* TORX screwdriver set - ''behind Electronics bench, opposite Woodworking''<br />
* Hex key set - Metric & Imperial/US, boxed - ''behind Electronics bench, opposite Woodworking''<br />
* Hacksaws: Junior (6") and full size (12") - ''Hanging up behind the Woodworking bench''<br />
: A full size hacksaw is an effective means to cut metal from 3 mm to over 50 mm thickness. Also useful for hard plastics.<br />
: Our Amtech 12" hacksaw needs four full turns after taking up the slack to tension the blade. Spare 12" 18 TPI and 24 TPI blades are hanging with the hacksaws. The spare 6" blades are in the spare drills box on the power-tool shelves the other side of the window.<br />
: ''There's more to using a hacksaw than you might think - incorrect blade tension or wrong choice of blade for work thickness, can ruin a blade in minutes and make your job much harder and slower. See [https://www.youtube.com/playlist?list=PLZgJvC8P7mk3g9v3mnW1MfpgUWiOkIfwr How to use a Hacksaw] - a 26 m video series covering basics, cutting straight, and how to cut thin metal without damaging the blade - by 'Course You Can' (Jim Garratty).''<br />
<br clear=all><br />
<br />
= Equipment and Tool Defect List =<br />
Stuff that's usually available, but is currently broken, (or recently fixed) should be on our [[Equipment and Tool Defect List]].<br />
<br />
''This is not a 'live' defect list, and tools/equipment may fail unexpectedly between its update and your intended visit.''<br />
<br />
=Computers=<br />
<br />
===Printers and Scanners===<br />
[[Printers_and_scanners]]<br />
===Servers===<br />
We have a [[Server_Novo|Debian Linux-based server in the loft space.]] It provides multi-user access into the space via SSH and has local copies of open source software repositories for fast installation of donated/refurbished computers.<br />
* Server (HP DL380 g3)<br />
* VMware server (ESXi 4.1)<br />
<br />
===Desktop computers===<br />
* Windows PC in the office/Laser Cutter room. See [[Laserpc]]<br />
* 2 Linux PCs under 3D Printing bench<br />
* All-in-one Apple Mac next to Electronics bench,<br />
;Other<br />
: Hard drive duplication station [[http://cpc.farnell.com/integral/inssdhddsatacopy/drive-dock-sata-copy-station/dp/CS20331]]<br />
* SIM card cutter (micro and nano)<br />
* Assorted old laptops and old workstations<br />
* Laser printer (mono)<br />
<br clear=all><br />
=Other facilities=<br />
===Bathroom===<br />
Yes we have one of those. Wheel chair accessible.<br />
<br clear=all><br />
===Kitchen===<br />
[[File: Kitchen2.jpg |200px|right | Kitchen ]]<br />
Kettle, sink, {{strikethrough|fridge}}, cups a plenty, ... <br />
<br clear=all><br />
<br />
==Items Needed==<br />
* Check out our [[WantList]]<br />
<br clear=all></div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_OpenSCAD_stuff&diff=17633Ian M's OpenSCAD stuff2024-02-22T21:16:23Z<p>IanM: /* Laser Cutting with OpenSCAD */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br><br />
<br><br />
I'm collecting my [https://openscad.org/ OpenSCAD] notes here. If you are looking for a tutorial for beginners you are in the wrong place as I doubt they'll ever be that well organized, but do check out my [[#Useful Links|'links']] section below.<br><br />
<br><br />
OpenSCAD is 3D CAD for people who prefer writing code to clicking and dragging stuff in a GUI. It uses its own declarative (functional) language to construct the object to render. In spite of its somewhat 'C'-like syntax, its very different 'under the hood' as variables are more like constants in other languages as they are immutable for the duration of their scope. i.e. '''a=a+1;''' is illegal. [https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/FAQ#Why_am_I_getting_an_error_when_writing_a_=_a_+_1? {ref}]<br><br />
<br><br />
Constraints are solely the responsibility of you the programmer to code and enforce. 'Vanilla' OpenSCAD without any libraries can be a PITA when constructing complex objects as you the programmer have to keep track of every dimension of every primitive shape to position them correctly relative to each other. However there are libraries that can hide much of the complexity - see below.<br />
<br />
== Customizer ==<br />
The [https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Customizer OpenSCAD customizer] is very powerful, but by default, every variable that you define at the top level in your file before any module definitions appears in it. Often, that's not what you want as many of them are probably being used as named constants to avoid sprinkling [https://en.wikipedia.org/wiki/Magic_number_(programming)#Unnamed_numerical_constants magic numbers] throughout your code.<br />
As the customizer only works on simple values, making the right hand side of the assignment an expression by appending +0, e.g.<br />
C=299792458 +0; // Speed of light (m/s)<br />
will exclude it from the customizer. Unfortunately enclosing the value in parentheses () is not sufficient.<br><br />
<br><br />
Alternatively, as noted in the documentation section 'supported variables', exclude all subsequent lines of the file from customization, by defining *any* module with a compound body (i.e. wrapped in braces {} ), even if null. e.g.<br />
module __Customizer_Limit__ () {} // end customizations<br />
<br />
If you *do* want to let a variable be customizable, it is generally worth explicitly specifying its limits and increment (which must be numeric - you cant use expressions or other variables) on the line defining it so the customizer displays a usable slider for it, e.g.<br />
lottoNum=13; //[1:1:49]<br />
and if its name isn't self explanatory, provide a comment describing it on the immediately preceding line.<br />
Grouping related variables into 'tabs' (which extend till the next named tab) using:<br />
/* [Tab Name] */<br />
can greatly help clarify which variables do what.<br />
<br />
== Variable scope and special variables ==<br />
Special variables are any variable with a name prefixed by $. Variables are immutable for the duration of their scope (either the file, or from the preceding { to the next } at the same level) and variables from enclosing scopes are inherited unless redefined. When you invoke a module or call a function, it does *NOT* inherit ordinary variables from its invoking/calling scope, but does from its definition's enclosing scope. Special variables are inherited from the invoking/calling scope so can be used to pass in data like parameters do. The *only* way to pass data back out of a scope is if that scope is the body of a function (from = to the terminating ;) as its return value. You cant 'leak' data from an inner to an outer scope via any type of variable. Running the sample code found at https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Other_Language_Features#Special_variables and carefully examining what it echoes to the console may help your understanding of OpenSCAD's scope rules.<br />
<br />
== So what's this $fa, $fs and $fn stuff? - smoothing arcs and circles ==<br />
Some OpenSCAD special variables are 'special'er than others because they control how OpenSCAD behaves. [https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Other_Language_Features#$fa,_$fs_and_$fn $fa, $fs and $fn] control how any constant radius curve or curved surface is rendered. That includes any sort of arc, and specifically the sphere and cylinder object primitives.<br />
<br />
OpenSCAD doesn't and cant output real arcs or curves when it renders an object as it outputs the surface of the compound object as a closed mesh of triangles, so it has to break up any arc into straight line segments. $fa, $fs and $fn control the resolution with which it does so. $fa is the minimum angle each segment will subtend, $fs is the minimum segment length, and $fn overrides the other two if non-zero and is the number of segments to use for a full circle, reduced pro-rata for arcs of less than 360°. See the link above for how they are used to calculate the segment length. The default value of $fa gives thirty segments in a full circle, but the default value of $fs is one, so at a bit under 10 units diameter, circular objects will start dropping segments, eventually becoming pentagonal when they get small enough.<br />
<br />
This is obviously undesirable when you are trying to construct a 3D printable part that needs bolt holes etc. You could override it by setting $fn but a high number of segments is computationally very costly - at least O(n²) for doubly curved surfaces - so setting $fn too high globally can lead to impracticably high render and preview times for complex models. Setting $fn locally is the best choice when a certain curved component or feature must be smoother than the rest. Otherwise, globally set $fs to an appropriate value for the print technology, 0.1 to 0.2 is 'in the ballpark' for most FDM print modelling, and set $fa to 360/N to choose the max segments N for larger circles. $fa still impacts rendering time, with smaller being worse, but at least you wont be attempting to render M3 bolt holes with μm precision!<br />
<br />
Another common use for setting $fn locally - usually within the parameters of circle() or cylinder() - is to generate regular polygons and regular prisms. e.g. <br />
<pre>cylinder(h=3.2, d=7/cos(30), $fn=6);</pre><br />
will generate a hexagonal prism the size of a M4 nut - 3.2mm thick, 7mm across flats. Note the division by the cosine of half the subtended angle of each face, to compute the diameter of the encompassing circle from the desired width across opposite faces.<br />
<br />
To get a feel for their effect try the following which renders a stack of disks of decreasing size, and adjust the customizer sliders, remembering that $fn must be zero for the others to be effective. If it isn't obvious, zoom in on the smaller disks at the top of the stack.<br />
<br />
<pre><br />
$fa=5;//[1:60]<br />
$fs=0.5;//[0.05:0.05:5]<br />
$fn=0;//[0:90]<br />
<br />
rs=[0.2,0.3,0.5,0.8,1,1.5,2,3,5,8,10,15,20];<br />
<br />
for(i=[1:len(rs)]){<br />
r=rs[i];<br />
translate([0,0,5*(len(rs)+1-i)])<br />
cylinder(h=3,r=r);<br />
}<br />
</pre><br />
<br />
== Scripting OpenSCAD ==<br />
You can run OpenSCAD from the command line and either silently render to a file or launch the GUI with command line options for preset customization or setting variables. See: [https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Using_OpenSCAD_in_a_command_line_environment Using OpenSCAD in a command line environment] in its user manual for details.<br />
<br />
Note that any variables set using the -D option have file scope and silently override any pre-existing file scope definitions for them in the file. They are persistent while the OpenSCAD GUI remains open. To clear the -D set variables, restart OpenSCAD!<br />
<br />
'''-D''' ''<varname>'''''='''''<value>''<br />
<br />
repeated for as many ''<varname>'' as you want to set, each with its own '''-D'''. If setting string variables you'll probably need to escape the quotes(") after the = and at the end of the string. See your OS specific documentation for command line / shell escape sequences for special characters.<br />
<br />
As an example, see: [[Ian M's £99 ZHUHAI CTC DiY I3 3D printer#5 July 2022 - Visualizing the bed levelling mesh|Visualizing the bed levelling mesh]] in my CTC DiY I3 printer blog page, for how I send the bed levelling mesh data from a Pronterface script (Python) to OpenSCAD for visualization.<br />
<br />
== What's BOSL2 and why should I use it? ==<br />
BOSL2 is the Belfry OpenScad Library, v2 (see link and description in [[#Recommended Libraries|'Recommended Libraries']] below). In this section I intend to show various cases where BOSL2 will make your life much easier. Lets start with:<br />
=== Threading ===<br />
[[File:NonBOSL screw.png|thumb|M10 male thread rendered with 'vanilla' OpenSCAD ]]<br />
Threaded objects in 'vanilla' OpenSCAD, without BOSL2 or any other threading library are a PITA!<br />
<pre><br />
//M10 thread parameters<br />
OD=10;<br />
P=1.5;<br />
L=15;<br />
TD=0.92;<br />
<br />
$fa=1; $fs=0.3; <br />
</pre><br />
<snipped 33 lines of support modules & functions + comments. See: [[File:NonBOSL screw.zip]]>[[File:NonBOSL screw section+profile.png|thumb|Cross-section and thread profile]]<br />
<pre> <br />
//Generate the thread cross section (XY plane) <br />
shape2=concat(arc2l(OD/2,ang=[0,22.5]),arc2l(OD/2,ang=[22.5,135],ri=-3.2*TD),arc2l(OD/2-TD,ang=[135,225]),arc2l(OD/2-TD,ang=[225,337.5],ri=3.2*TD),arc2l(OD/2,ang=[337.5,360])); <br />
<br />
linear_extrude(height = L, twist = -360*L/P)<br />
polygon(shape2); //Do the threaded rod<br />
</pre><br />
Note the complexity of building the cross section of the M10 thread, and that's before you even dig into what my arc2l() function does. It will probably take you an hour or two to match the thread form to the specification if you need to change it, and you have to look up the thread parameters manually for each size you want to be able to render<br />
<br />
With BOSL2 that reduces to:<br />
<pre><br />
include <BOSL2/std.scad><br />
include <BOSL2/screws.scad><br />
$fa=1; $fs=0.3; <br />
screw("M10", length=15);<br />
</pre><br />
and you can simply specify the screw by named size. Apart from coarse and fine ISO (metric) threads, [https://github.com/revarbat/BOSL2/wiki/screws.scad screws.scad] also handles UNC and UNF and a couple of other. If you need a Whitworth or BA thread you'll have to provide the profile and use the generic threading modules in [[https://github.com/revarbat/BOSL2/wiki/threading.scad threading.scad]]<br />
<br />
=== Pyramids! ===<br />
''Elsewhere 'M' wrote:''<br />
<blockquote><br />
I use ''%GUI_CAD%'', but struggle with it. Mostly because I use it infrequently and have to start over every time.<br />
<br />
Last time, I wanted a simple 3D trapezoid (flat top pyramid) and could not figure out all the dimensions. I have not gone beyond dropping in simple shapes and modifying them. It would be easy some times to start with a cube and then draw a slicing plane or line to complete a plane, but none of that is apparent how to do.<br />
</blockquote><br />
''(Nym and CAD software used anonymized for privacy) and I replied:''<br />
<br />
[[File:Truncpyramid.png|thumb]]In 'vanilla' OpenSCAD, a truncated square right pyramid is simply:<br />
<br />
<pre>rotate([0,0,45]) cylinder(h=10, d1=20*sqrt(2), d2=10*sqrt(2), $fn=4);</pre><br />
You may well ask what does a cylinder have to do with a pyramid?<br />
Well OpenSCAD allows you to use the cylinder object to make right regular prisms, by setting the number of vertices (and thus sides) with which it renders round objects. The $fn=4 thus gives four sides. You can also use the cylinder object for cones and frustums - you get a cone if you set r1 or d1 to the base size and r2 or d2 to 0 for a point at the top. Set r2 or d2 to a size smaller than the base and you get a frustum. The only remaining complexity is the '''*sqrt(2)''', and that's because when using $fn to make prisms, the diameter (or radius) gives the circumcircle, so we are effectively specifying the diagonal of the base and top squares, not their side length, so by Pythagoras, we need that correction factor. Finally as the circumcircle is divided into four equal sides starting with a vertex at angle 0, rotating it 45 deg about the Z axis brings the base and top sides parallel to the XY axes.<br />
<br />
If you are using OpenSCAD with the BOSL2 library, its a lot simpler:<br />
<pre>include <BOSL2/std.scad><br />
prismoid(size1=20, size2=10, h=10);</pre><br />
as prismoid specifically creates rectangular prisms and frustums.<br />
<br />
[[File:Bentpyramid.png|thumb]]It also easily allows you to stack them e.g. to model the [https://en.wikipedia.org/wiki/Bent_Pyramid Bent Pyramid of Sneferu] at a scale of 1:10000 (assuming the usual 3D printing convention of using mm as the unit):<br />
<pre>include <BOSL2/std.scad><br />
prismoid(size1=18.943, size2=12.358, h=4.704) attach(TOP) prismoid(size1=12.358, size2=0, h=5.767);</pre><br />
I find it a lot easier to explore OpenSCAD, simply keeping the 'vanilla' and BOSL2 cheatsheats bookmarked in my browser, than it is to explore the myriad modes of ''%GUI_CAD%'' to find a reasonable method to do anything semi-fancy.<br />
<br />
=== Bezier Curves ===<br />
[[File:Bezier.png|thumb|The Excel97 GUI Bezier Editor]]<br />
BOSL2 has various functions and modules to aid generating and using [https://en.wikipedia.org/wiki/B%C3%A9zier_curve#:~:text=A%20B%C3%A9zier%20curve%20(%2F%CB%88b,by%20means%20of%20a%20formula. Bezier curves]. However it lacks easy click & drag customization of the curve as the OpenSCAD customizer doesn't have any 'click in the plot' coordinate setting functionality, or even X and Y sliders for points, and also borks lists of lists, so I wrote an Excel 97 spreadsheet to generate OpenSCAD Bezier points lists for three, four and five control point Bezier curves.<br />
<br />
It should work in Excel 97 - 2003. Excel 2007 onwards lack the capability to drag plot points<sup>*</sup>. <br />
<br />
''* It may be possible to get point dragging (or at least GUI manipulation) back with the (depreciated) [https://web.archive.org/web/20170904131448/https://blogs.office.com/en-us/2009/11/02/excel-add-in-for-manipulating-points-on-charts-mpoc/ MPOC addin] (which you have to get from a 3rd party site as Microsoft have killed it and all related pages - try the Internet Archive [http://download.microsoft.com/download/9/D/D/9DDA9AFB-A349-41F5-9757-70D4DBA9238D/MPOC.zip [here<nowiki>]</nowiki>] to download) but as I don't have Excel 2007 or higher, that's untested and YMMV!''<br />
<br />
[[File:Bezier.xls]]<br />
<br />
==== A nose cap for the RML Dremel ====<br />
The original went walkabout many moons ago and genuine ones are ridiculously expensive so we needed to 3D print one. <br />
[[File:DremelCapProfile.png|thumb|A Bezier curve for the outer profile of the cap, to generate a solid of revolution]] <br />
[[File:DremelCap.png|thumb|A render of the complete cap]]<br />
Note the use of multiplication by a scaling matrix:<br />
<pre>bezier_points*[[Xscale/100,0],[0,Yscale/100]]</pre><br />
to scale the fixed size curve to the parametric cap diameter and length.<br />
<br />
The complete code:<br />
<br />
<pre>include <BOSL2/std.scad><br />
include <BOSL2/beziers.scad><br />
include <BOSL2/threading.scad><br />
<br />
//Dremel:<br />
//thread len 8.8mm plain 2.5mm total 11.3mm#<br />
//collet nut od 10.6mm<br />
<br />
/* [Thread (US inch)] */<br />
D=0.75; <br />
TPI=12; <br />
<br />
/*[Other Parameters (Metric)][*/<br />
// Diameter of Dremel body at nose<br />
OD=22.6;<br />
// Length of noze<br />
tl=11.3;<br />
// unthreaded length at base of nose<br />
ul=2;<br />
// Thickness (additional length) of cap<br />
cl=2;<br />
// Hole dia. for spindle<br />
id=12;<br />
/*[Printer calibration]*/<br />
//See BOSL2 wiki: Constants.scad: $slop: Calibration<br />
$slop=0.3;//[0:0.05:0.35]<br />
/*[Arc resolution]*/<br />
$fa=5;<br />
$fs=0.1;<br />
<br />
module __Customizer_Limit__ () {} // end customizer<br />
$dd=0+1E-3;<br />
bez=[[100,0],[102.62,74.95],[85,85],[159.96,102.1],[100,100]];<br />
<br />
*debug_bezier(bez, N=len(bez)-1); // show only with ! or exclude with *<br />
<br />
pl=close_path(concat([[0,0]],bezier_curve(bez, 32),[[0,100]]));<br />
<br />
//render() // only needed for graphics cards with broken OpenGL<br />
diff("x"){<br />
// "x" cuts<br />
tag("x") threaded_rod(d=D*INCH, l=tl+2*$dd, pitch=INCH/TPI, internal=true){<br />
attach(BOTTOM,BOTTOM,norot=true)<br />
cyl(d=D*INCH+4*$slop,h=ul+INCH/(2*TPI),chamfer2=INCH/(2*TPI)) ;<br />
attach(TOP,BOTTOM,overlap=$dd)<br />
cyl(d=id+4*$slop,h=cl+$dd)<br />
attach(TOP,BOTTOM) cyl(r=OD,h=10)<br />
;<br />
attach(BOTTOM,TOP) cyl(r=OD,h=10);<br />
} //end "x" cuts<br />
down(tl/2) rotate_sweep(pl*[[OD/200,0],[0,(tl+cl)/100]]); // Plain<br />
//down(tl/2) textured_revolution(pl*[[OD/200,0],[0,(tl+cl)/100]], "ribs",[2,0.2],tscale=0.6); // Ridged for grip<br />
}</pre><br />
<br />
''I printed it on my CTC DiY I3 at home, and it fitted my non-Dremel rotary tool nicely, so I knew the thread's OK. The next Tuesday I fitted it to the RML Dremel, and it turned out to be a very nice snug fit, with a barely noticeable ridge at the transition between cap and body.''<br />
<br />
=== TLDR: Use BOSL2! ===<br />
<under construction><br />
<br />
== BOSL2 Issues ==<br />
<br />
=== The documentation doesn't match! ===<br />
Sometimes you find that when you paste (complete) example code from the BOSL2 wiki into OpenSCAD, it doesn't work and you get a '''WARNING: Ignoring unknown function''' ... or '''WARNING: Ignoring unknown module''' ... error. <br />
<br />
Looking in your local copy of the corresponding BOSL2 library source file, you find the function or module has a different name or is simply missing. This usually doesn't mean the wiki is wrong, as its a big hint that your BOSL2 is out of date and you need to download it again (as the documentation is usually updated to reflect the current state of development). Archive a copy of the previous version in case the new version breaks any of your older OpenSCAD BOSL2 projects.<br />
<br />
There is a BOSL2 version number, currently<sup>*</sup> 2.0.652, which you can interrogate but it isn't much use for checking code compatibility as it hasn't been incremented since last year, and usually isn't 'bumped' for changes that break backwards compatibility!<br />
<br />
''* as of August 2022''<br />
<br />
=== Reading the BOSL2 documentation on Github restricted ===<br />
When browsing the BOSL2 wiki, while not logged in to Github, you may get an error page:<br />
: Access to this site has been restricted<br />
It can be triggered by only following a few links, and is persistent, blocking all access to any Github pages (including login). It is believed to be related to the number of large images on some of the BOSL2 wiki pages resulting in hitting a bandwidth threshold when skipping through pages. It may clear after ten minutes inactivity. Alternatively try clearing all Github cookies and restart your browser. If you get it, you will need to log in to Github to prevent it recurring, as persisting unauthenticated may result in an IP ban.<br />
<br />
== Laser Cutting with OpenSCAD ==<br />
Has its own page: [[OpenSCAD to Laser Cutter]]<br />
<br />
Also see: B. M. Sleight's Lasercut library (link below)<br />
<br />
== Measuring stuff in OpenSCAD ==<br />
OpenSCAD unfortunately doesn't let you select stuff in the render window, or drag stuff and get a numeric position, but sometimes it is useful to be able to get dimensions off a rendered object. My answer to that is a cursors library that generate two XYZ crosshairs that you can move around by customizer sliders or 'bumping' the coordinate directly, so you can visually line them up with the features of interest, and read off the distance between, azimuth and elevation in the console window. Get it here: [[File:Cursors.zip]]<br />
<br />
== Recommended Libraries ==<br />
https://github.com/BelfrySCAD/BOSL2 - The Belfry OpenScad Library, v2. A massive 'Swiss Army Knife' library that handles nearly everything you'll need to construct complex objects. e.g. attaching child objects to anchor points on a parent without having to worry about their absolute position, rounding/chamfering edges and corners, screw threading and more other stuff than you can shake a stick at. My #1 recommendation for *any* OpenSCAD user.<br><br />
<br><br />
https://github.com/bmsleight/lasercut - B. M. Sleight's Lasercut library handles extracting 2D geometry from components of a 3D model and 'plating' the result for laser cutting. See full description in the [[OpenSCAD to Laser Cutter#Recommended Libraries for laser cutting|Libraries section]] of my OpenSCAD to Laser Cutter page<br />
<br />
== Useful Links ==<br />
https://mastering-openscad.eu/ - "Mastering OpenSCAD: within 10 projects" by Jochen Kerdels, ISBN: 978 3753 458 588<br />
<blockquote>The book Mastering OpenSCAD introduces you to all important concepts and functionalities of OpenSCAD. The book guides you through 10 selected projects step by step, each project focusing on a limited set of functions and concepts. After these 10 projects, you will know all practically relevant features of OpenSCAD. For the sake of completeness, a final chapter briefly presents the functions that were not addressed in any of the projects.</blockquote><br />
Read online for free [https://mastering-openscad.eu/buch/introduction/ [here<nowiki>]</nowiki>] or buy the [https://www.amazon.co.uk/dp/3753458589 paperback from Amazon].<br />
<br />
<br />
https://www.reddit.com/r/openscad/ - Reddit: r/OpenSCAD - a fairly popular<sup>*</sup> unofficial forum for OpenSCAD discussions. The [https://forum.openscad.org/ official forum] originally was integrated with the OpenSCAD mailing list, but Nabble broke that so its mostly inactive.<br />
<br />
''* 29 threads in the last month, when I wrote this.''</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=File:Cursors.zip&diff=17632File:Cursors.zip2024-02-22T21:14:00Z<p>IanM: Measurement Cursors for OpenSCAD</p>
<hr />
<div>== Summary ==<br />
Measurement Cursors for OpenSCAD</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=File:Rotate_vect_test.zip&diff=17631File:Rotate vect test.zip2024-02-22T20:47:02Z<p>IanM: OpenSCAD Vector rotate() demo for ChrisN</p>
<hr />
<div>== Summary ==<br />
OpenSCAD Vector rotate() demo for ChrisN</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Blog_2024&diff=17629Blog 20242024-02-21T21:37:53Z<p>IanM: /* 2024-02-13 Tuesday */</p>
<hr />
<div>== 2024-02-20 Tuesday ==<br />
* Pierre continued with his PTZ mount build, with a laser cut frame on top of a 'Lasy Susan' for rotation and an axle turned down at the ends to fit the bearings which eventually carry the tilting part<br />
<gallery><br />
PierrePTZ.jpg<br />
PierrePTZ2.jpg<br />
</gallery><br />
* IanM was helping people again and introduced Pierre to turning steel on the lathe<br />
* Steve was working on some faulty DC-DC converter modules<br />
Others?<br />
== 2024-02-13 Tuesday ==<br />
* Pierre is designing a PTZ camera mount<br />
* Mark has joined the throngs of the laser cutters<br />
* MarkQ came to do some laser cutting<br />
* Andrew journey to fix all the 3d printers continues<br />
* IanM was helping people and doing some lathe work<br />
* Steve continues fixing his light<br />
* Andy opened and did some marquetry<br />
<br />
== 2024-02-06 Tuesday ==<br />
* BenF was laser cutting some signs<br />
* Steve is repairing a shed light powered by a solar panel<br />
* Andrew was fixing 3d printer<br />
* AndyH opened and ran before the road was closed<br />
* ChrisN was 3d printing some more train pillars<br />
* Ian.M was <br />
* PaulE was coding<br />
<br />
== 2024-01-30 Tuesday ==<br />
* Andrew was learning how to setup a raspberry pi, assisted by Andrew<br />
* Chris was continuing some 3d printing and working with Fusion 360<br />
* Mat came to see us and started learning Fusion 360<br />
* Pierre came to learn the lasercutter<br />
* Steve was mending a light and looking at fixing a battery, also helping...<br />
* Kev with some soldering <br />
* Andy did some inductions on the laser for 3 people and gave some limited hints on Fusion<br />
* Andrew was looking at 3d printing and helping setup the Pi<br />
* Paul was coding<br />
<br />
== 2024-01-23 Tuesday ==<br />
Regulars: Paul E, Andy, Andrew, IanM<br />
* Garret came along and was good to see him, looked at fixing a calculator<br />
* Andrew and his son came along for the <br />
* Chris came for the first time and we showed him some 3d printing<br />
<br />
== 2024-01-16 Tuesday ==<br />
Regulars: Paul E, Martin, Andrew<br />
* Anand - CO2 sensor<br />
* Mark - intro to laser cutter<br />
* David - laser engraving, kartcher cleaner that doesn't run<br />
* Cath M - dehumidifier that needs fixing<br />
<br />
== 2024-01-09 Tuesday ==<br />
* Andy opened<br />
* Regulars: Ian M, Andrew, Martin, Paul E<br />
* Steve - assisted a soldering task<br />
* Peter - came for inspiration on a project<br />
* David - laser cutting plywood for a box<br />
* Wendy and Deborah - had a steam cleaner that needed fixing<br />
* Anand - soldering headers on more boards<br />
* Lucas and Zac - introduction to 3D printing<br />
* Catherine - introduction to 3D printing<br />
<br />
== What we have been doing at Little House ==<br />
<br />
Previous years blogs are available from the [[Main_Page| Main Page]]</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=File:PierrePTZ2.jpg&diff=17628File:PierrePTZ2.jpg2024-02-21T21:36:29Z<p>IanM: PierreW's PTZ mechanism, by PierreW</p>
<hr />
<div>== Summary ==<br />
PierreW's PTZ mechanism, by PierreW</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=File:PierrePTZ.jpg&diff=17627File:PierrePTZ.jpg2024-02-21T21:35:50Z<p>IanM: PierreW's PTZ mechanism, by PierreW</p>
<hr />
<div>== Summary ==<br />
PierreW's PTZ mechanism, by PierreW</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=File:Lathe_Induction_Bushing.pdf&diff=17626File:Lathe Induction Bushing.pdf2024-02-18T13:18:14Z<p>IanM: /* Summary */</p>
<hr />
<div>== Summary ==<br />
Engineering drawing of a flanged bushing for Lathe Induction training. Uses ~15 mm of 12 mm / 1/2" dia. brass stock. Demonstrates the four key lathe skills: facing, turning, drilling, and parting off. Created by Ian.M for RML.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_Lathe_Notes&diff=17625Ian M's Lathe Notes2024-02-18T13:17:16Z<p>IanM: /* Manuals */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br />
<br />
''Currently these notes are semi-organized and non-authoritative. As I become more experienced with the RML CJ18A mini-lathe, I'm cleaning up, extending and reorganising them. Some lathe operating experience is assumed. If in doubt, '''*ASK*''' me, Andy H<sup>*</sup> , Jonathan H or another experienced minilathe operator!<br />
<br />
''* Andy H should be asked (for an authoritative answer) any questions involving RML usage policies or acquiring tooling or materials through RML.''<br />
<br />
== The Lathe ==<br />
Our Facilities page [[Facilities#Lathe|has]]:<br />
<blockquote><br />
'''Lathe'''<br />
[[File: Lathe2.jpg |200px|right | Lathe]]<br />
In the kitchen. <br />
<br />
Marked as a CJ18A Mini-Lathe from [[https://www.amadeal.co.uk/acatalog/CJ18A-Mini-Lathe-7x14-Machine-100mm-3jaw-Metric-With-Metal-Gears-AMA_LA_CJ18_M_3_MGRB.html Amadeal]]<br />
[[https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Manual]] <br />
<br />
[[Media:Lathe InductionNotes.pdf| Induction Document]]<br />
<br />
Possible upgrades:<br />
*https://www.youtube.com/watch?v=GwT-JQLbNPA<br />
<br />
''Please do not use the lathe until you have received induction'' <br />
<br clear=all><br />
</blockquote><br />
Its a Chinese import 7x14 mini-lathe. The 7x14 refers to the maximum diameter and length of work, in inches and is only a theoretical measure of the working envelope as you loose length to the chuck + any tailstock tooling, and the diameter is over the bed, not the cross-slide. See actual specifications below. <br />
<br />
Most if not all Chinese 7x10 to 7x16 mini-lathes seem to be remarkably similar (not uncommon with Chinese products due to [https://www.bunniestudios.com/blog/?p=284 Shanzhai (山寨)] )<br />
and the OEM of our Amadeal CJ18A Mini-Lathe was probably [https://www.made-in-china.com/showroom/cheap-lathe Yangzhou Realbull Machinery Co. Ltd]. Very similar lathes are also made by [https://www.siegind.com/lathe-machine.html Sieg], but their lathes tend to be slightly less sophisticated than the equivalent Realbull models.<br />
<br />
''N.B. Many Sieg parts are known to have slight but critical differences from Realbull parts, so '''DON'T''' order Sieg spares for a Realbull lathe!<br />
<br />
== Key Specifications ==<br />
Amadeal says the CJ18A Mini-Lathe is a 7x14 model with:<br />
<blockquote><br />
* Power 550 W<br />
* Distance between centres : 350 mm<br />
* Swing Over Bed: 180 mm<br />
* Swing Over Cross Slide: 110 mm<br />
* Taper: MT3<br />
* Tailstock Taper: MT2<br />
* Chuck diameter: 100 mm<br />
* Spindle Speed: 50 - 2500 rpm ''(with digital readout)''<br />
* Spindle Bore: 20 mm<br />
* Cross slide Travel: 65 mm<br />
* Range of Metric Threads: 0.5 - 2.5mm.<br />
</blockquote><br />
* The lead screw is metric, pitch 1.5 mm.<br />
* The spindle center is 90.6 mm above the flat of the bed (measured).<br />
<br />
Even though the compound and cross slide handwheels appear to be calibrated in thousandths of an inch, as ours is a metric machine, they only approximate that. One turn of a slide handwheel is 1mm advance, and they have 40 divisions, so each division is 0.025 mm, (approx. 0.984 [https://en.wikipedia.org/wiki/Thousandth_of_an_inch thou]). Similarly, the tailstock quill advances 1.25 mm per handwheel turn, which has 50 division dial, giving the same 0.025 mm divisions, but only 4 turns per 5 mm. The carriage handwheel is awkward - it moves approx. 19.2 mm per turn, and doesn't have a dial scale.<br />
<br />
== Notable Accessories ==<br />
We have:<br />
* [https://www.amadeal.co.uk/acatalog/160mm-Face-Plate-for-the-4-Mini-lathe-AMA_AC_CJ18A_FP160RB.html#SID=129 160 mm (6 1/4") Faceplate]<br />
* 100 mm (4") three jaw self-centering chuck (OEM standard) 22.5mm bore, with inside and outside jaw sets<br />
* 100 mm (4") four jaw (independent) chuck with reversible jaws (8 TPI screws)<br />
* Tailstock drill chuck (max. 13 mm dia.)<br />
* Live center for tailstock (+ OEM fixed center) <br />
* Four way Tool Post (OEM Standard)<br />
* [https://www.amadeal.co.uk/acatalog/Quick_Change_Tool_Post_for_the_mini-lathe.html Quick Change Tool Post] + 3 tool holders<br />
* [https://www.amadeal.co.uk/acatalog/Fixed-Steady-for-Mini-Lathes-AMA_AC_CJ18A_FSRB.html#SID=145 Fixed Steady Rest]<br />
* [https://www.amadeal.co.uk/acatalog/Travelling-Rest-for-Mini-Lathes-AMA_AC_CJ18_TSRB.html#SID=144 Travelling Steady Rest]<br />
<br />
''You'll find all of the above on the shelf above the lathe, with the accessories in the wooden box, apart from the steadies, which live next to it. Change gears, spare parts, and most cutting tool tips/blanks are in labelled white rectangular tins behind the lathe.''<br />
=== Measuring Tools ===<br />
We have:<br />
* Various dial indicators - the one with the adjustable magnetic base stand is the most convenient for most lathe setup work.<br />
* 25mm micrometer (in little grey case)<br />
* Grey case containing set of measurement tools including dial calipers, micrometer, steel rule (metric & inch), engineers square, and a fish-tail gauge<br />
<br />
''We currently lack''<br />
* ''A tool height setting gauge''<br />
<br />
=== Hand Tools ===<br />
Some common tools needed for normal use are kept with the lathe, in or attached to the wooden accessories box:<br />
* 2 mm Allen key - adjusting cross-slide and compound gibs<br />
* 4 mm Allen key - quick change toolholder tool clamping screws + height adjust, tightening dials<br />
* 5 mm Allen key - four way toolpost tool clamping screws, engaging/disengaging threading indicator<br />
* 6 mm Allen key - locking/unlocking quick change toolholder<br />
* 8 mm spanner - locking carriage when 8 mm socket can't be used, locking gib adjuster nuts <br />
* 13 mm spanner - changing chucks, locking steady rest jaws<br />
* Very long needle nose pliers - for grabbing swarf safely, holding one end of emery cloth safely so you can keep your fingers away from the jaws, and extricating small objects from awkward places.<br />
<br />
== Change Gears ==<br />
[[File:BC puller 1.jpg|thumb|Custom puller for B-C stub shaft]] [[File:BC puller 2.jpg|thumb|Pulling the B-C stub shaft]]<br />
See "Conquest Super Lathe" manual ([[#Manuals|below]]), section '''4.7 Change Gears''', PDF pages 28-29, but see below for mesh adjustment. The LittleMachineShop.com "Mini Lathe User’s Guide" (also below) section '''Threading''' gives a far better explanation, with pictures and diagrams, but its for a lathe with a US 1/16 inch pitch leadscrew, not a metric 1.5 mm pitch one like ours, so you *MUST* ignore all the tables in that section, replacing them with metric mini-lathe (with 1.5 mm pitch leadscrew) equivalents. <br />
<br />
We have the following tooth count gears: 20,20, 30, 35, 40,40, 45, 50,50, 60,60, 80,80<br />
which consist of the OEM power feed gears + the metric change gear set. Apart from the metal 20 tooth pinions, they are all plastic, probably Delrin if the molded in 'POM' marking can be trusted, but possibly plain Nylon 6, and are metric Module 1.<br />
<br />
If we wanted to add the capability to cut US/Imperial threads we'd need to buy additional 55, 57 and 65 tooth gears, and possibly a 21 tooth metal pinion.<br />
<br />
CGTK's [https://www.cgtk.co.uk/metalwork/calculators/changegears/minilathe?gears1=20,20,30,35,40,40,45&gears2=50,50,60,60,80,80&gears3= Change Gear Calculator] ''(link preloaded with our gear list)'' is useful if you don't want to calculate the ratios from first principles. Not all suggested combos will physically fit.<br />
<br />
* Take care *NOT* to loose the keys in the A and D shaft keyways - turn each shaft till the keyway is up before removing the gear. <br />
* The B and C gears are coupled by a hollow stub shaft (with an integral key), which is so tight in the gears it has to be pressed or driven out - I've made a puller just for this task, kept in the change gears tin.<br />
* The center of the B-C stub shaft *MUST* be lubricated where it runs on its pin on the change gear banjo bracket, with grease or heavy oil. ''Seizure of the stub shaft due to running dry is a frequent cause of catastrophic mini-lathe geartrain failures!''<br />
* Don't get oil on the change gears as it can cause plastic gears to crack. Only PTFE drylube or plastic compatible white grease should be used on their teeth. <br />
* Adjust the B-C pin position in the straight slot first to set the C to D gear mesh, tighten its nut, then swing the whole banjo about the D shaft boss to set the A to B mesh, and finally tighten the banjo clamping nut.<br />
* Check both gear meshes have running clearance by turning the chuck by hand enough to complete one full turn of the leadscrew, and by attempting to turn the intermediate gear(s) to assess backlash, If excessive resistance is felt or if there's significant backlash, readjust the gears. If you have difficulty judging the mesh, a strip of 80 gsm copier paper (approx. 0.1 mm thick) wound into the meshing teeth before tightening the stud or banjo will give appropriate clearance once removed. Once setup, check the gears run quietly under power.<br />
* If the sum of the tooth counts C+D is the same as for the ones you just removed and they were correctly meshed, you don't need to move the stub shaft pin. If A+B is <u>also</u> the same, you don't need to move the banjo. e.g. If it was set up for 16:1 reduction power feed, 1 mm (40:60 - 50:50) for M6 and 1.5 mm (e.g. 40:60:40) for M10 pitches can thus be achieved by only swapping gears. <br />
<br />
''The change gears, puller, etc. and a box spanner for the banjo nut are kept in a white rectangular tin behind the lathe.''<br />
<br />
=== Power Feed ===<br />
When used for turning with power feed, the change gears should be set for a 16:1 reduction (A:20 : B:80 - C:20 : D:80) using the pair of small metal 20 tooth pinions and the 80 tooth plastic gears (largest in set), for a feed of 0.09375 mm per turn (1.5 mm/16). Unless continuing your threading project the next session, please re-fit the 16:1 power feed set after threading so the power feed is ready for use. <br />
<br />
* *ALWAYS* leave the feed direction selector lever in its neutral (no feed) position, and the half-nuts open after use.<br />
* *ALWAYS* check the carriage lock is disengaged before engaging power feed. Unlock the carriage after use. <br />
<br />
=== Threading Dial ===<br />
The threading dial is an aid to re-engaging the half-nuts at the right moment so the tool will retrace its previous path cutting deeper, rather than offsetting axially some fraction of the thread pitch and ruining your work. Its based on the concept of the lowest integer multiples of the leadscrew and thread ''(being cut)'' pitches that exactly match, but for mechanical simplicity it only covers certain selected multiples of the leadscrew pitch.<br />
<br />
We have a choice of three pinion gears:<br />
{| class=wikitable<br />
|+ Threading dial Pinion Gears<br />
|-<br />
! Teeth !! Colour Dot !! Usable lines !! OD gear !! Dist. per turn<br />
|-<br />
| 14 || Red || 1,7 || 7.51 mm || 21 mm<br />
|-<br />
| 15 || Orange || 1,5,9 || 8.05 mm || 22.5 mm<br />
|-<br />
| 16 || Green || 1,4,7,10 || 8.37 mm || 24 mm (2 mm/div)<br />
|}<br />
They are now colour coded, with a paint dot on the gear end face ''(the only non-wear surface)''. The 16 tooth one is normally left on the lathe, but disengaged when not threading to minimise wear on the lead screw. The others are kept in the Change Gear tin.<br />
<br />
There's a threading dial 'pickup' calculator here: https://www.cgtk.co.uk/metalwork/calculators/threaddialindicator <br />
<br />
Initially select ''Lathe:'' '''Custom''', and enter the following below:<br />
* ''Units:'' '''Metric'''<br />
* ''Lead Screw Pitch (mm):'' '''1.5'''<br />
* ''Thread Dial Indicator Gear Teeth:'' '''16,15,14''' <br />
* ''Lines on Thread Dial Indicator:'' '''12''' <br />
* ''Line Marking:'' '''Every Line Numbered'''<br />
Note the teeth list is entered in reverse order so the resulting table highlights any required pinion changes.<br />
<br />
N.B. The dial is only friction clamped to the pinion by its center screw. If you have any reason to suspect it may not be properly aligned: <br />
# With the power off and the carriage unlocked, engage the feed direction lever upwards. You'll probably need to turn the chuck by hand to get it to engage.<br />
# If the threading indicator isn't already engaged, loosen the threading dial support block bolt, pivot the block to engage the pinion with the leadscrew and retighten the bolt.<br />
# Engage the half nuts, again turning the chuck by hand till they drop in. <br />
# Turn the chuck a couple of turns, top towards you to take up any backlash, then lock the carriage, taking care not to push it left while locking it.<br />
# Loosen the screw securing the dial to the pinion.<br />
# Align the '1' line of the dial with the index line, by rotating the dial clockwise, then retighten the screw.<br />
# Don't forget to disengage half-nuts and unlock the carriage!<br />
<br />
The above instructions should result in the half-nuts engaging cleanly when exactly on any valid line when threading towards the headstock. If it is required to thread away from the headstock, there will be a slight offset from the line due to backlash between the spindle gear and leadscrew, so engage slightly early.<br />
<br />
Changing the pinion:<br />
# Loosen the threading dial support block bolt and disengage from the leadscrew.<br />
# Undo dial center screw, and remove it and the dial, dropping the old pinion out the bottom.<br />
# Oil the shaft of the new pinion with a drop of light oil and insert it from below, gear end down.<br />
# Refit dial and screw.<br />
# Check the dial and pinion turn freely with minimal resistance.<br />
# Align as above.<br />
<br />
== Tailstock and Steadies ==<br />
These are mostly used to support long work ''(long with respect to its diameter)'' to improve rigidity, increasing accuracy and reducing chatter. The Tailstock quill is also used with a drill chuck for drilling.<br />
=== Tailstock ===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock base]]<br />
The tailstock can be offset to turn shallow tapers between centers. We don't currently have the accessories to turn between centers, namely <s>a MT3 dead center for the spindle, or</s> any drive dogs for the work. Also realigning the tailstock after turning a taper can be a PITA. The photo shows the tailstock adjusting screw locations ''(C - Lateral, and D - Skew)'' and the block on the baseplate they engage with. Adjustments can only take effect when the tailstock locking lever is eased to take the pressure off the baseplate. As we don't have a MT3 center, one has to turn a fresh point on a test workpiece for a rough tailstock alignment reference. Fine alignment, to avoid inadvertent taper turning, can be done by mounting a long precision ground bar between the chuck (or preferably a center in the spindle), and a dead center in the tailstock and sweeping it with a dial indicator on the carriage. Finally a test cut should be taken at either end of a bar between centers, and the diameters checked with a micrometer. Assuming the bed has previously been properly levelled and shimmed to take out twist ''(not the case at RML as we don't have it bolted down)'', any remaining difference in diameter will be double the tailstock offset, smaller at the tailstock being offset towards the front. Fine adjustment cant be achieved by jacking with the screws, its best to ease the adjusting screws, bump the tailstock into alignment then take up the screws again, checking the alignment is maintained when the tailstock is unlocked and relocked. There is no vertical adjustment, though shims can be added between the tailstock and its base.<br />
<br />
==== Tailstock Quill ====<br />
There is a metric/imperial scale on the top of the quill, read against the end of the tailstock, for depth measurement when drilling. The tailstock quill has a 1.25 mm pitch thread and a 50 division dial. Each division is therefore 0.025 mm, and it only takes 4 full turns of the handwheel to move the quill 5 mm. <br />
<br />
To eject MT2 taper tooling and centers from the tailstock, wind the quill all the way in.<br />
<br />
N.B. The quill anti-rotation pin (dog-tip setscrew + locking nut in top of tailstock near to the quill lock) is only M5. It will sheer if a large diameter drill jams in the work. Please back it out clear of its keyway if using large drills, and use alternative methods of preventing chuck rotation. To re-engage it, crank the quill out till you can see the keyway, align it with the screw and screw in the screw till it gently bottoms out, then back it off a quarter turn. Try twisting the quill to check its properly engaged, then tighten the locking nut gently to hold the screw in position clear of the bottom of the keyway.<br />
<br />
=== Steady Rests ===<br />
We have two, both with brass tips that must be kept lubricated during use.<br />
<br />
The fixed steady mounts on the ways, and is most useful when turning longer work that wont fit through the spindle bore. Adjustment is critical, and the surface the tips run on must be smooth and concentric, as any misalignment that forces the work off center will result in the work wobbling in the chuck, marring it, with a high risk of it becoming un-chucked, which can be dangerous at speed.<br />
<br />
The travelling steady mounts to the headstock side of the carriage to locally resist the deflection of thin long work, due to the cutting forces. It only has two tips, to resist climb, and deflection away from the tool, and requires readjustment after every cutting pass.<br />
<br />
== Tooling and Tool Holders ==<br />
'''Key dimensional data:'''<br />
* The quick change holders accept up to 10 mm shank tools. <br />
* The four way toolpost has 50 mm long sides, a seat width of 15 mm and can clamp tools of up to 5/8" (15.875 mm) shank ''(check this)'', but the slot base is only 10.4 mm below the spindle center so cannot be used with >10 mm shank tooling unless it has a dropped tip. Large tooling with a centered tip is also problematic as you run out of height above the shank when trying to shim to match the spindle center height. <br />
<br />
===Quick Change Toolpost===<br />
I've got the quick change toolpost and toolholders setup for mostly easy use. The three toolholders came with cantilever height setting arms which historically haven't been installed as the supplied fixing screws were too short. That's all now sorted out and a HSS RH turning tool and a HSS hand-ground grooving/parting-off tool are now mounted in two of the holders and set to height. The third is kept free for other tools. <br />
<br />
The quick change toolpost has been modified with a spring to press the dovetail clamp outwards and help stop it twisting or flopping about to ease toolholder fitting and removal. The dovetail clamp (socket headed screw on toolpost side opposite dovetail) feels a bit stiffer than before, but will take less than half a turn to go from open (with the toolholder lifting out or dropping in easily) to fully clamped. As there is so much less clearance in the open position you should no longer need to wiggle the toolholder while clamping it to get a consistent height. If the dovetail clamp ever gets misaligned, twist it straight by eye, slacken off a bit further than usual to get a toolholder on, clamp it to align the dovetail then release, reseat the toolholder and re-clamp to ensure its at its preset height. You cant adjust the height by 'jacking' with the height screw due to its offset leverage. Instead, back off the height screw and hold the toolholder at the desired height while locking the dovetail clamp, then adjust the height screw (and locking nut) to hold it there, then check it doesnt change height significantly when you unclamp and reclamp the dovetail. <br />
<br />
Unfortunately the OEM height setting screws foul the toolpost locking nut handle. Currently, if you need to swap toolposts you will have to first remove the quick-change tool holder from the post. There is enough nut handle swing to allow the quick change toolpost to be unclamped and rotated to fine set the tool angle without removing the toolholder. It also seems the mating surfaces may be slightly out of square, as if you rotate the toolpost 90° or 180°, the nut swing may be insufficient to re-clamp it without removing the toolholder to do so. Add a M10 washer under the locking nut if the handle ends up pointing in an undesirable direction! A thin M10 washer is kept with the toolpost collar for this purpose, and will shift the handle position by about a third of a turn. <br />
<br />
''ToDo: Make a taller nut of a similar pattern, to clear the height setting screws.''<br />
<br />
===Four Way Toolpost===<br />
The OEM four way toolpost is significantly more rigid than the quick change toolpost + holders because it has fewer and thicker parts and less overhang. Therefore the four way toolpost should be used when using carbide tooling. It requires shimming under the tool to set the tip height to the spindle center height - see below. The tool shanks are mostly significantly less than 15 mm wide, so need to be centered under its clamping screws, tempting as it is push the shank in for full side contact with the toolpost. If possible clamp the shank with all three screws not just two.<br />
<br />
==== Shimming ====<br />
We typically only mount up to two tools, and want maximum rigidity, so use 50 mm x 15 mm shims, (the full seat area), preferably with deburred edges and radiused corners so they aren't a hazard to the operator.<br />
<br />
We have pre-cut and marked shims of the following thicknesses: <br />
* 1x 3.23 mm, 2.42 mm, 1.56 mm, 0.32 mm, and 0.25 mm<br />
* 2x 1.00 mm, 0.77 mm, 0.12 mm, 0.11 mm, 0.10 mm and 0.05 mm<br />
* 4x 0.53 mm<br />
<br />
Our shims are mostly found materials (hence the awkward thicknesses) and are mostly a mixture of aluminium and steel, with a couple of GRP ones. The toolpost seat '''<u>must be absolutely clean</u>''' to avoid embedding debris in the aluminium or GRP shims, to get a consistent height and avoid tilting the tool - wipe it every time you change a tool! Put the thin shims at the bottom of the stack to avoid the tool shank edges creasing them. Shims are kept in a little yellow plastic box with a clear lid, near the carbide tools case.<br />
<br />
I made a tool height setting gauge (T shaped black acrylic with steps in its sides) which can be used to check the tool tip height matches the spindle center height using either the flat of the ways or the saddle as a reference. The tool tip should just fit under the lip of the appropriate step, with the T arms across the ways flats or on the saddle. It is kept in the box with the carbide insert tools.<br />
<br />
''ToDo:'' <br />
<br />
* ''Cut more shims neatly, mark them with their thickness.''<br />
* <s>''Do test cuts and start noting shim stack-ups for various tools.''</s><br />
* ''Organise shim storage!''<br />
<br />
=== HSS Tools ===<br />
[[File:Tool Bit Geometry.jpeg|thumb|Single point cutting tool geometry]]<br />
Our HSS tools are made from 8 mm square bar stock, hand-ground to tip profile in-house. See LittleMachineShop's [https://littlemachineshop.com/images/gallery/instructions/grindingtoolbits.pdf Grinding Tool Bits] notes. <br />
<br />
I've installed our usual HSS LH turning and parting off tools in two of the quick change holders and set the heights correctly. There are a couple of other HSS tools or tool blanks knocking about. Taking heavy cuts turning steel (even with good cutting oil) blunts HSS tools fairly quickly, which are time-consuming to re-sharpen nicely without a dedicated tool & cutter grinder with appropriate jigs. Its worth noting that the usual 'speeds & feeds' tables are commonly based on surface speeds expected to give a half hour (active cutting) tool life before resharpening.<br />
<br />
I touched up the LH turning tool by lapping on wet & dry (silicon carbide) paper on glass (Aka: [https://en.wikipedia.org/wiki/Scary_sharp 'Scary Sharp']) working upwards through the grits 200, 400, 600 and finally 1000, initially 'bluing' the surfaces to be lapped with a marker pen to see which areas needed taking down more. The end of the tool was significantly uneven so I touched that up freehand on the bench grinder to flatten it when it became apparent that 200 grit lapping wasn't cutting where it needed to. There was an existing micro-bevel on the leading side, which I kept. Finally I 'dubbed' the leading corner vertical edge on the 1000 grit to give it a very slight nose radius. A test cut on brass gave a very nice finish when turning.<br />
<br />
''Ian B has purchased some spare 8mm HSS tool blanks - talk to a lathe trainer if your proposed lathe work needs custom ground HSS tooling.'''<br />
<br />
=== Brazed Tungsten Carbide Tools ===<br />
Somewhat of a half-way house between hand ground HSS tooling and insert tooling with the disadvantages of both and some more besides - e.g. they are much harder to sharpen. So why do we bother? Some tool geometries would be awkward and tedious to hand grind, and Chinese import brazed carbide tooling is about half the price of similar HSS tooling, and far more readily available. Also, for space constrained tooling like boring bars, if you want carbide, for insert tooling, the size of the insert and its clamping seriously limits the minimum hole diameter you can work in. I have purchased a set of 3/8" shank brazed carbide tipped boring bars, but we currently cant sharpen them, due to lack of a diamond grinding wheel. <br />
<br />
=== Tungsten Carbide Insert Tools===<br />
Decoding ISO insert tooling part numbers: https://www.cutwel.co.uk/blog/learn-the-turning-tool-iso-code-system<br />
[[File:Carbide set.jpg|800px|thumb|left|Our set of Tungsten carbide insert lathe tools (before the new inserts were fitted)]]<br />
<br />
{| class=wikitable<br />
|+ Tools, left to right, (+ last across top):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| SSKCR0610H06 || 75° through boring || SCMT06204 || Long || 6 || 6.34 || ''4.33''<br />
|-<br />
| SSSCR0610H06 || 45° deep facing, internal chamfering || SCMT06204 || Long || 6 || 6.13 || ''4.58''<br />
|-<br />
| SWUCR0610H05 || 93° boring, deep facing || WCMT050308 || Long || 6 || 6.22 || ''4.48''<br />
|-<br />
| SWGCR0810E05 || 90° RH turning & facing || WCMT050308 || Short || 8 || 8.25 || '''2.45'''<br />
|-<br />
| SSSCR0610E06 || 45° turning, chamfering || SCMT06204 || Short || 8 || 8.75 || ''1.93''<br />
|-<br />
| SSBCR0610E06 || 75° RH turning, chamfering || SCMT06204 || Short || 8 || 8.72 || ''1.98''<br />
|-<br />
| LW0810R-04 || 60° external threading || JCL15-120 || Short || 8 || 7.44 * || ''3.28''<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || 8.23 || ''2.5 ?''<br />
|-<br />
| LN0813R-04 || 60° internal threading || JCL15-120 || Long || 7.95 || 7.44 * || ''3.28''<br />
|}<br />
<br />
{| class=wikitable<br />
|+ More Tools, (loose in tin):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || ~8.5 (not in use) ||<br />
|-<br />
| [https://www.glanze.co.uk/product/glanze-12-mm-60-degree-metric-internal-threading-tool/ Glanse SIR0012K11] || 60° internal threading bar || 11IRA60 || Long || 12 dia || ??? || ???<br />
|}<br />
''Shim stack heights in bold are tested, in italic are only calculated.'' ''Tip heights marked * are with new JCL15-120I inserts. The single remaining plain JCL15-120 insert has a slightly higher tip height.''<br />
<br />
Carbide tooling typically requires two to three times more speed than HSS and at least a couple of 'thou' depth of cut for best results.<br />
<br />
Chatter can rapidly kill carbide tooling by chipping the cutting edge. To improve rigidity and reduce the risk of chatter, the cross-slide and compound gib screws need to be well adjusted so there is minimal play in the slides, tool stick-out should be minimised, the four way toolpost should be kept over the cross-slide, and the work should be kept close to the chuck (or otherwise supported by tailstock or steady rest) to avoid excessive deflection.<br />
<br />
Thermal shock is almost instant death to carbide, and when dry cutting the insert tip can run very hot, so do not add extra cutting fluid manually during the cut. Pre-apply what you need, evenly, before starting the cut.<br />
<br />
Parting off or facing to center is high risk - if the tool tip is even slightly below center or if tool or work deflection takes it below center, the work will tend to climb over the tool tip as the cut approaches center, breaking the insert. To avoid this, the tool should be shimmed slightly above center, sufficient to allow for work and tool deflection, and unless very close to the chuck, a steady should be used. Its often preferable to part to a couple of mm dia. remaining then stop and saw through the remainder, then clean up by facing. Parting off hollow parts is much lower risk.<br />
<br />
Further investigation of the Tungsten carbide insert tool height situation is not encouraging - the so-called 'set' in question does not have a consistent tip height ''(see above table)''! In a real set, the insert seats *should* be machined allowing for the insert thickness to bring all the cutting edges to the same height with respect to the shank underside. However if you place them tip to tip on a table its easy to see there is considerable height variation, so they need to be individually shimmed (or at best, one machined shim will only be right for two or three tools). At this time we don't have dedicated shim stacks for each tool.<br />
<br />
A 2.42 mm thick shim brings the SWGCR0810E05 90° RH turning & facing tool almost exactly to center height, and good results were obtained turning 1" steel pipe. However facing 50mm steel bar stock to center found it to be slightly low, leaving a fractionally under 0.05 mm 'pip' so it needs another 0.03 mm to bring it fractionally above center. Fractionally too high is generally preferable to fractionally too low, due to tool deflection, so adding an 0.05 mm shim to the stack should produce optimum results.<br />
<br />
==== Inserts ====<br />
Ian B has purchased the spare inserts we needed in sets of five. He even was able to get the CK3 parting-off inserts which had been difficult to source!<br />
<br />
Inserts used in above tool set:<br />
* 3x SCMT06204 (square, indexable) https://www.rdgtools.co.uk/acatalog/SCMT-06-Carbide-Insert.html<br />
* 2x WCMT050308 (triangular, indexable) https://www.rdgtools.co.uk/acatalog/WCMT-05-T3-08-5XTIP-8813.html<br />
* 2x JCL15-120 (60 deg threading point) https://www.rdgtools.co.uk/acatalog/X5-JCL-15-120L-THREADING-TIPS-60-DEGREE--X5-TIP---23455.html<br />
* CK3 (parting off) https://www.rdgtools.co.uk/acatalog/CK3-CARBIDE-TIPS---PARTING--BOX-OF-5PCS--9437.html<br />
<br />
Inserts used in other tools:<br />
* 1x CK3 (as above) also missing from spare parting off tool<br />
* 1x 11IRA60 in Glanse threading bar + 1x spare<br />
<br />
=== Drills ===<br />
Various sizes of center drills are kept in a plastic bag next to the wooden accessories tray. There's also a small box of 2.5 mm center drills.<br />
<br />
We have a set of 11 TiN coated HSS drill bits from 1.5 to 8 mm, (in a cylindrical plastic index box) for tailstock drilling of brass, aluminium and non-abrasive plastics. To keep them sharp enough for the precision work we expect from the lathe, please don't use them for steel or reinforced plastics, and don't borrow them for non-lathe use. Metric and US [https://littlemachineshop.com/reference/numberdrillsize.php numbered]/[https://littlemachineshop.com/reference/letterdrillsize.php lettered] general use HSS drill bits are kept in two red metal index boxes next to the drill press.<br />
<br />
== Using the Lathe ==<br />
=== General ===<br />
Making dimensioned parts is primarily done by touching off the tool tip on a reference surface (with the lathe stopped, turning the chuck by hand), zeroing the handwheel dial, then manually counting turns and divisions. When backing off the tool its best to do so by exactly one whole turn so you don't forget the previous dial position. Stopping and measuring the work before taking the final cuts is essential if high accuracy is required. ''I've changed out the dial setscrews for flat tip ones with a tiny slug of solder under them so the dials are now friction fit on their shafts. i.e. if you hold the handle firmly taking up the backlash in the direction of cut, you can zero the dial just by grabbing and twisting it.''<br />
<br />
Carriage movement is less easy to measure as the handwheel is uncalibrated and advances an awkward bit over 19.2 mm per turn. Your options here when shoulders or other features must be exactly positioned are, in order of increasing accuracy: <br />
* Use measuring instruments, scribe the work at the desired length then work to the scribed line. Its often convenient to black the work with a permanent marker, then scribe with the tool tip, turning the chuck by hand.<br />
* for short distances, lock the carriage and use the compound, set parallel to the work<br />
* Set up a long travel dial indicator to measure carriage motion. <br />
N.B. with the leadscrew stopped, and the threading dial engaged, with its default 16 tooth gear, it will make one turn for every 24 mm of carriage movement (2 mm/div). This isn't accurate enough for positioning but is sufficient to check you aren't out by a whole mm or more.<br />
<br />
Do not allow any solvents to contact the chuck guard clear plastic as it will make the plastic brittle, or even craze it, and try to avoid melting it with the work light!<br />
<br />
===Speeds & Feeds===<br />
The surface speed of the tool relative to the work (or visa versa) is important, and best results will be achieved when it is in a tool type and material specific range. Because the surface speed is proportional to the diameter and the spindle RPM, it is usual to vary the spindle speed in inverse proportion to the diameter to get the surface speed in the desired range, and keep it there as the tool tip moves closer to the spindle axis. <br />
<br />
A cutting speed chart for HSS tooling, published by Model Engineer magazine can be found [https://www.model-engineer.co.uk/sites/7/documents/cutting%20speed%20chart.pdf [here<nowiki>]</nowiki>]. The second row is the target feed rate and the rest of the chart, apart from the diameter column is RPM.<br />
<br />
For carbide tooling cutting iron and steels, recommended speeds are generally three times higher than for HSS, but the CJ18A 2500 RPM max. spindle speed (in high gear) means you can only reach the optimum speed range for over 15 mm dia work. For small diameter work, HSS tooling may well be a better choice.<br />
<br />
An online metric speeds calculator is here: https://www.cgtk.co.uk/metalwork/calculators/cuttingspeeds <br />
<br />
How to do the maths to calculate speeds and feeds: https://www.cutwel.co.uk/blog/speeds-feeds-made-easy<br />
<br />
If you can hear the lathe 'sing' as it cuts, you are getting chatter, which invariably results in poor surface finish. Try decreasing (or possibly increasing) the spindle speed till the resonance stops. <br />
<br />
Once you have a wavy surface due to chatter, a light cut wont clean it up as the tool 'twangs' from peak to peak. You have to take a deep enough cut to get under it. For precision parts, its therefore desirable to take a trial finish cut while still 0.5 mm or so oversize, to give an opportunity to tweak the cut to get a good finish, check for taper, and that the part wont be undersize (on your test finish cut nominal diameter).<br />
<br />
=== Slide Locks ===<br />
* The carriage can be locked to the ways using the M5 hex screw through the top of the saddle to the left of the cross-slide. Double check the leadscrew is disengaged and the half-nuts open before locking it. Lock it when facing.<br />
* The cross slide can be locked by a M4 socket headed cap screw just in front of its middle gib screw. Locking the cross slide is helpful when turning very shallow conical features where the cross slide handle is in the way of the compound.<br />
* The compound slide can be locked by a M4 socket headed cap screw in line with the edge of the toolpost mount on the side with the gib adjustment screws. In normal use it should be kept backed off half a turn but it is desirable to tighten it for parting off operations to keep the resulting end faces flat.<br />
<br />
=== Compound ===<br />
The compound consists of a locking swivel and a top slide allowing cuts to be made at an angle to the axis e.g to produce bevelled or tapered features. There is a difference between US and UK usage, in the US a compound angle of 0° means the compound slide is parallel to the cross slide, but in the UK, 0° is parallel to the ways. The compound angle indicator on the CJ18A follows UK practice, 0° parallel to the ways, but it is not to be trusted, its out by a few degrees!<br />
<br />
One of the deficiencies of the CJ18A lathe is the difficulty of setting the compound angle. It is held and locked by two screws hidden under the top half of the compound slide, which must be wound back till its toolpost end is clear of the pivot point to access them. This may have to be repeated several times to snug them up enough to tap it to the desired angle, then finally tighten them. <br />
<br />
We generally keep the compound slide set approximately parallel to the ways so it can be used for short-distance longitudinal positioning without measuring. However it is unlikely to be closely parallel unless a test bar has been swept with a dial indicator on the slide, or test cuts made on a large OD workpiece and checked for taper.<br />
<br />
=== Chucks and Chuck Jaws ===<br />
==== Terminology ====<br />
* Inside jaws have steps on the outside to grip the ID of hollow work, but can also be used as outside jaws on small diameter parts (i.e. that fit through the spindle). <br />
* Outside jaws have steps on the inside to grip the OD of the work.<br />
* Universal chucks have a scroll plate with a spiral screw thread that moves all the jaws.<br />
* Independent chucks have individual adjusting screws for each jaw.<br />
<br />
==== The Chucks ====<br />
* The three jaw universal chuck can only grip near round or hexagonal work, which it centers, but its concentricity is not perfect so e.g. if you reverse the work and continue turning at the same diameter from the other end, you will see a line where the turned surfaces meet. It has separate sets of inside and outside jaws, and we normally keep the inside set installed to use as outside jaws for small diameter work.<br />
<br />
** Our jaws are individually numbered, stamped in the groove. They must be fitted in the correct sequence. The jaw slots are not clearly marked. Lowest runout for small dia. parts is achieved if you fit the jaws with #1 anticlockwise of the makers mark, then continue anticlockwise for #2 and #3.<br />
** A large strong rubber band is a great help getting all the jaws started on the scroll together - with slots #1 and #3 above the centerline and the scroll thread outer tip between #1 and #3, insert jaws #1 and #2 and put the rubber band round them to keep them in their slots. Insert jaw #3 and stretch the rubber band over it to hold it up into its slot. If the scroll was positioned correctly, all jaws should be at the same initial radius. The jaws can now be cranked in with the chuck key and they should all engage in step so they meet in the middle.<br />
:: ''Mini-lathe.com have the best instructions for [https://www.mini-lathe.com/mini_lathe/chucks/chucks.htm#Installing_Chuck_Jaws changing the jaws].'' <br />
<br />
* The four independent jaw chuck can grip most roundish or squarish work, which can either be carefully centered by the user, or deliberately gripped off-center. <br />
** Its jaws are reversible so can be swapped from inside to outside by simply cranking each jaw out and reinserting it the other way round, one at a time. DON'T move the jaws to different slots as they are likely to bind.<br />
** When setting up to face the sides of rectangular objects held crossways, it may be helpful to use both inside and outside jaw orientations, in symmetrical opposing pairs.<br />
** Its screws move their jaw 1/8" (3.125 mm) per turn<br />
<br />
* The jaws must '''never''' protrude from the chuck OD by more than one step, and for safety, its preferable they don't protrude at all, as they make the gap between the front of the bed and the chuck body an even more unforgiving meat grinder, and as the number of teeth engaged with the scroll or screw decreases, they loose strength, just when you need it the most to grip larger/heavier work. <br />
<br />
''Neither chuck is well suited to gripping tapered work safely. When seating work that doesn't quite fit through the chuck bore (which is larger than the 20mm spindle bore limit), be careful that it isn't seating on the chamfered edge of the chuck bore as it is far to easy to get the work slightly cocked so it doesn't run true.''<br />
<br />
==== Changing Chucks ====<br />
* When changing chucks, use the small grey plastic mat to protect the ways under the jaws in case you drop the chuck.<br />
* The spindle nose has two patterns of holes - the three hole pattern is for the three jaw chuck and the faceplate, and the four hole pattern is for the four jaw chuck. One hole is shared between the patterns, and is marked on the spindle nose.<br />
* To fit a chuck:<br />
** First check that the spindle nose and chuck back and recess are free of swarf, grit or other debris. Any foreign objects will tilt the chuck causing excessive runout and may mar the surfaces.<br />
** Remove the nuts and split lock washers from its studs, line its studs up with the hole pattern (preferably with the stud nearest anticlockwise to the makers mark through the marked spindle hole), fit and hold it in place with your right hand, and with your left, get the lock washer and nut on the top stud, and take up the slack.<br />
** One one nut is on, you no longer have to worry about dropping it, and can work round fitting the remaining washers and nuts, taking up the slack on each as you fit it. <br />
** Next, work round again getting them all finger tight, then tighten them gently, and finally work round fully tightening them. <br />
* Removal is the reverse of refitting. Put the washers and nuts back on the chuck's studs so they don't get lost.<br />
<br />
==== Gripping Threaded Work ====<br />
It is generally undesirable to chuck work gripped on a screw thread, as it is difficult to hold the work securely and get good concentricity while avoiding crushing the thread crests. However, if one must, one of the better ways of doing so is to wind a wire helix to fit the thread then clamp on the outside of the wire so it seats on the flanks of the thread. The wire should be mild steel or soft iron for steel parts and copper for aluminium and brass parts, single strand, round and of uniform diameter a little less than the thread pitch. It can be wound on the lathe, in reverse, by chucking a sacrificial mandrel of the same diameter and thread pitch, hooking the end of the wire round or under the jaw, against the direction of rotation, then holding the other end of the wire under tension with pliers and starting the lathe dead slow. Once wound and removed from the mandrel, the ends must be trimmed then it should be screwed on to the threaded work to provide a surface to chuck on.<br />
<br />
=== Faceplate Work ===<br />
Faceplate work is probably the most dangerous operation you can (or rather should) perform on a lathe. The working area is a large diameter spinning surface with protruding clamps to fixture the part that it is impractical to guard. Protruding clamps, studs, nuts etc. are very difficult to see at speed.<br />
<br />
'''Treat the faceplate with great respect and caution if you wish to continue to be able to count to ten on your fingers!''' <br />
<br />
The 65 mm cross-slide travel vs the 80 mm faceplate radius is a serious limitation that may require creative compound, toolpost and tool setups for larger parts, and doing full face cuts in two sections.<br />
<br />
''It is common practice to skim the faceplate to ensure it runs true. We have not (yet) done this, and wont till the spindle is in better bearings and the nose reground to minimise runout.''<br />
<br />
==== Clamping ====<br />
Open ended/sided clamps should be oriented so that cutting forces drive the work towards the clamping bolt/stud, not out from under the clamp. Minimize the protruding length of thread past the clamping nut, if necessary using sacrificial bolts or studs you can cut to length, or even using a long M8 stud for one of the faceplate mountings, so you can get a clamp nearer to the faceplate center. Double-check all clamps are secure, manually turn the faceplate to check the work and clamps clear the ways, top-slide and toolpost, and stand out of the 'line of fire' (a disc extending from the faceplate) when spinning up the work for the first time. <br />
<br />
If you need to machine close to a clamp, consider marking a safe limit circle on the faceplate and work with a marker pen to make it easier to see how close the cutting tool is to crash disaster. <br />
<br />
I strongly advise reading chapter two of Tubal Cain's book "Workholding in the Lathe" several times before your first faceplate setup, and if possible get another experienced lathe user to check your first few setups before spinning them up.<br />
<br />
==== Chuck Guard Removal ====<br />
The faceplate is too large diameter to fit under the chuck guard, but the guard has an interlock switch wqhich must be closed for the lathe to run. The guard is now fitted with wing nuts so it can be removed allowing the the interlock switch to close when using the faceplate. It *SHOULD* *ALWAYS* be refitted if a chuck is fitted, except when turning work too large to clear the guard. <br />
<br />
''The chuck guard is primarily there to make it very difficult to start the lathe without removing the chuck key and to reduce the area of large diameter spinning surface exposed. It may slow down the projectile if a chuck sheds a jaw but is unlikely to stop it. Also it serves to contain coolant spray spun off the chuck. As we don't use flood coolant this usually isn't an issue for us. As setting up for faceplate work doesn't use a chuck key, and the most hazardous zone is the face of the faceplate, with its spinning projecting clamps, with full access required for machining operations, which a guard would not cover, the consensus is that removing the guard is an acceptable risk.''<br />
<br />
=== Turning and Facing ===<br />
We are getting good results in aluminium, brass, and even steel using HSS cutting tools in quick-change tool holders, and the ~ 94 um/turn power feed. Unfortunately due to lack of rigidity in both the machine and smaller diameter parts, if you don't want the outer end to be over diameter, a light final cut and multiple 'spring' passes will probably be required.<br />
<br />
For aluminium, a sharp HSS tool and 0.5 mm (20 div) depth of cut gives good results with power feed for rapid stock removal. Its also easy maths as each cut takes ~ 1 mm off the diameter. Finish cuts should be much finer, 0.1 mm (4 div) is 'in the ballpark'.<br />
<br />
For steel, using carbide insert tooling, a 0.25 mm (10 div) depth of cut is more appropriate, and with pre-applied cutting oil, gives reasonable results with power feed if you use enough speed. The maths is not quite so easy as you are only taking 0.5 mm off the diameter per pass. Again, use finer finish cuts but try to plan your cuts so the final cut is still cutting, not smearing the surface!<br />
<br />
When facing or parting off, some skill is required to turn the cross-slide handwheel steadily to get a decent finish and to avoid shock-loading the tool tip. Increasing the spindle speed in one or more steps to keep up with the reducing diameter is advisable, but avoid speeds that cause resonances (resulting in chatter). When parting off, small through-hole parts may be caught on a thin rod chucked in the tailstock, and pre-positioned inside the work with its tip right up to the parting off position.<br />
<br />
==== Using the Steady Rests ====<br />
For the fixed steady rest, see Blondihacks' Lathe Skills #26 - How To Use a Steady Rest! [[#Youtube_Playlists_&_Videos|{below}]]<br />
<br />
Ours doesn't have ball bearing fingers, so a smooth surface on the work and adequate lubrication are essential. The thumbscrews can only tighten the fingers, so for small adjustments outwards you need to either slack off the clamping nuts or ease them slightly and use a drift against the back of the finger's slot. Once set, check the chuck still turns freely.<br />
<br />
The traveling steady rest needs to run on a machined surface, so at least for the first pass, must follow the tool, so its difficult to avoid using more compound slide overhang than is desirable. An initial surface should be cut next to the chuck or tailstock center before fitting the steady rest.<br />
<br />
Both are a PITA to fit - the fixed one has to have its clamping post inserted up through the bed, and the supplied spanner is useless near the headstock, and the travelling one's mounting holes on the saddle almost invariably need swarf picked out of them.<br />
<br />
==== Turning Between Centers ====<br />
<s>Using a MT3 to MT2 reducing sleeve, the MT2 dead center can be fitted in the spindle.</s> ''Currently the MT3 spindle taper is compromised.'' Alternatively, a soft center can be turned immediately before use in the three jaw chuck, but that must have its 60° point re-cut to concentric if the chuck is disturbed, and needs to be either large enough to bear on the chuck body, or must have a lip to bear on the end face of the jaws to take the axial thrust. Recutting the center is a PITA, as the compound angle must be set to 30° anticlockwise, then reset to a true 0° afterwards. Maybe a right-hand 30° end angle zero rake form tool is the answer, or use the carbide insert tool SSKCR0610H06 as a form tool with the toolpost rotated 15° anticlockwise.<br />
<br />
With the MT2 live center in the tailstock quill, this gives us a center either end of the work to hold it.<br />
<br />
We also need a drive dog similar to [https://littlemachineshop.com/products/product_view.php?ProductID=4473&category=1 this], and the corresponding drive post to bolt to the spindle nose. I have some 25mm bore thick wall iron pipe, which should do nicely. Lengths of the dog's straight tail and of the post TBD after I check how much the center protrudes. N.B. its recommended to tie the tail to the post to keep them in contact so they don't slam. ''Currently we will need to drive from the chuck jaws. Possibly use the exterior jaws with a short soft center gripped on the inside end and drive from the highest step.''<br />
<br />
=== Drilling ===<br />
Always start with a center drill so deflection of longer bits doesn't start the hole off-center. For larger bits (> 5 mm), first drill to the web size, then to final diameter. For a precision hole, drill slightly undersize and ream to final diameter. ''Supply your own reamers!''<br />
<br />
Caution: See note about the quill anti-rotation pin in section [[#Tailstock Quill|Tailstock Quill]] above.<br />
<br />
=== Boring ===<br />
Caution: As the spindle doesn't extend right through the headstock housing, if boring in a through hole, chips tend to fall out the back and tumble in the spindle bore till they fall into the change gears. To avoid this, one should plug the spindle bore with a wad of paper towel or rag and when cleaning up afterwards, use a rod to push it through towards the tailstock, with the chuck jaws (if fitted) wound clear of the spindle bore.<br />
<br />
A swivel bladed hole deburring tool (pale blue handle) can be found in the main room on the windowsill behind the drill press.<br />
<br />
A couple of boring jobs have been bodged with an awkwardly angled turning tool and achieving acceptable effective rake with enough clearance to reach deep enough into the hole has been problematic. I reviewed the tools we had and found none suitable for starting out in a 13mm bore, the max diameter we can (easily) drill. I therefore decided to buy a set of boring bars and make a holder for them. I had difficulty finding anything affordable under 10mm shank - the best low cost option was a [https://www.amazon.co.uk/dp/B07P5LGVBX set of nine 3/8" (9.525 mm) shank brazed carbide tipped boring bars], which would be close to the max capacity of the quick change boring bar holder - if we had one! Unfortunately this holder for our specific toolpost is difficult to find except in a toolpost bundle. Another annoyance is the variable tip height of the set, varying from 1.8 mm to 2.8 mm above the center of the shank.<br />
<br />
I therefore decided to make a boring bar holder of the [https://littlemachineshop.com/products/product_view.php?ProductID=1700 Littlemachineshop.com (USA) style] for use in the four way toolpost, as the additional rigidity will certainly help. Starting with a slightly over 50 mm length of 16 mm aluminium square bar and using the four jaw chuck , both ends were faced and an attempt was made to find its center and center drill it. It was then drilled out to ~9.8 mm after much drama due to blunt drills and drills that cut ~1mm oversize. Too big, but beggars cant be choosers as we didn't have a boring bar holder or a 3/8" reamer. Unfortunately the final hole ended up significantly off center. It was then chucked crossways and ~1 mm skimmed off its thickest side to gain clearance to allow it to be shimmed to height, then one side was slit lengthwise manually with a hacksaw.<br />
<br />
It was fitted to the for way toolpost and loaded with a booring bar, which clamped firmly. A 0.86 mm shim stack brought the tip of the largest boring bar almost spot on center height, with the difference easily accommodated by twisting the tool slightly. The three jaw chuck was then remounted, and a piece of iron pipe chucked for a test. It cuts well and leaves a decent surface finish.<br />
<br />
''The boring bar setup is a work in progress - talk to me before attempting to use them if you have a project that would benefit from boring..''<br />
<br />
ToDo: get something that can sharpen tools tipped with this grade of carbide - it needs some sort of diamond (or possibly CBN) wheel as green grit silicon carbide does little more than polish it. ''N.B. diamond wheels are rapidly eroded by grinding steel, so the supporting steel seat must be undercut with a regular grinding wheel before the diamond wheel can contact it.'' <br />
<br />
We'll also need 50 mm square sheet shims to fit under the toolpost to gain clearance in the toolpost above the tool or toolholder. A 2.4 mm shim would give us about the same above and below spindle center height, and we probably need a small selection of thinner ones.<br />
<br />
=== Thread Cutting ===<br />
The objective is to cut a thread that complies with the ISO metric thread profile. Our lathe is not currently equipped to cut non-metric threads, (with the exception of BA which have pitches based on metric threads of that era).<br />
<br />
[[File:ISO and UTS Thread Dimensions.svg|frame|center|Metric Thread Profile - from the geometry, H is ~86.6% of P]]<br />
<br />
Metric thread data - See 'Preferred Sizes' at: https://en.wikipedia.org/wiki/ISO_metric_screw_thread<br />
<br />
See "Mini Lathe User’s Guide" section '''Threading''' for general techniques *ONLY*, and above for change gears and threading dial setup.<br />
<br />
Amadeal specify the max. thread pitch as 2.5 mm. Any thread pitch greater than 1.5 nn requires the change gears to gear up. When gearing up it is desirable to distribute the ratio as evenly as possible over the two pairs of gears in the geartrain to avoid excessive tooth loading.<br />
<br />
==== External Threading ====<br />
Initially turn work to required Major Diameter, set up change gears and threading tool, touch off on the work, zero the top and cross slide dials, and do a 'scratch' pass to check the pitch. Back off the tool, return the carriage, and re-engage the half nuts on a valid dial line clear of the end of the thread then immediately stop the lathe, and hand turn the chuck till the tool tip is (hopefully) over the scratch to check the thread pickup. If all is good, return the carriage again, restart the lathe and start cutting your thread. <br />
<br />
Methods of doing so vary depending on the size of the thread and toughness of the metal, but straight-in plunge cutting is generally to be avoided as has the highest cutting forces, and does not reliably keep the carriage (and top-slide if set parallel to the work) loaded to avoid pitch errors due to backlash. <br />
<br />
If leaving the half-nuts engaged and reversing the lathe to return to the start of the thread for the next pass, its absolutely essential to back the tool out of the thread for the return pass as it will not follow the path of the cutting pass due to backlash in the geartrain, leadscrew mounts and half-nuts.<br />
<br />
==== Internal Threading ====<br />
''<nothing here yet>''<br />
<br />
== Cutting fluids ==<br />
=== Why bother? ===<br />
[https://youtu.be/mRuSYQ5Npek Watch this video] and contemplate what's actually happening to that thin ribbon of metal being removed. Most of the lathe's motor power is being turned into heat by internal friction in the chip being removed in the zone around the cutting edge, and surface friction at, and immediately behind the cutting edge, near-instantly heating the chip by up to several hundred degrees. Reducing the surface friction using a suitable cutting oil reduces the strain on the machine as a whole, and reduces workpiece and tool heating (and thus expansion) with consequent improvements in maximum usable feed and depth of cut, surface finish and accuracy. It also drastically increases the life of the cutting edge.<br />
<br />
=== Practicalities === <br />
We don't have a coolant system for the lathe and *really* don't want the maintenance hassles of using soluble cutting oil/coolant as if used infrequently its a PITA to keep recirculated high water content cutting fluids from going rancid and stinky, and they can also rust the ways, so even a total loss gravity feed system is problematic. Therefore if dry machining doesn't give a good enough finish, we tend to use oil applied topically, by hand to the work. <br />
<br />
* Hard brass is typically free-turning without oil, however some light oil for the final cut can improve surface finish, but with the disadvantage that it will increase loose chip buildup on the tool as hard brass typically forms short spalls or splinters rather than curly chips.<br />
<br />
* Many Aluminium alloys tend to be gummy, and Paraffin or other mineral spirits mixed with a little oil can help prevent the aluminum welding to the tool edge. WD40 will do at a pinch, but its messy to apply from a spray can.<br />
<br />
* Steel really needs *GOOD* cutting oil. Lard oil is the traditional choice for steel. If there are any objections to lard oil, we should bite the bullet and get some commercial dark high Sulphur cutting oil, but beware, many such oils use an additive package that includes lard oil.<br />
* Cast iron (except ductile) should be cut dry, as the carbon micro-inclusions self-lubricate it, and the carbide in the dust (primarily Cementite) are very abrasive, so tend to form a grinding compound if mixed with oil. <br />
<br />
I've sorted out an oil pot lid with a 1/2" brass collar soldered in to give a nice smooth sided hole, for ease of use and to minimize the risk of spills when using a brush to apply cutting oils, and got some dirt-cheap brushes. It fits Shippam's paste (and similar own-brand spread) jars and I've found several jars and ordinary lids to seal them for storage. Unfortunately it isn't the easiest to get this type of jars' lids back on square so they seal properly, and if you over-tighten them and there's a temperature change, they can be a total <expletive> to reopen. Using the rubberised handles of a large pair of pliers to grip the jar lid just above its rim is the best option, and avoids damaging the lids.<br />
<br />
''N.B. For the smaller brushes, the glue holding the bristles in is attacked by paraffin. To prevent loss of bristles, crimp the aluminium ferrule of each new brush of this type before use.''<br />
<br />
We have, in labelled jars:<br />
<br />
* Sulphurised Lard oil thinned with paraffin. Best choice for heavy cuts and threading in steel but stinky.<br />
* Lard oil thinned with paraffin. Good for steel and acceptable for softer copper alloys<br />
* Paraffin with a trace of light oil. Good for aluminium, and can help prevent squealing chatter on finish cuts in brass.<br />
<br />
I've also got some paraffin wax (in the form of a stubby candle), which can be applied lightly (under power) to brass and aluminium stock especially on the finish pass. It makes less mess than oil but unfortunately tends to build up on the tool tip, making it difficult to 'work by eye' without frequent pauses to clean the tool tip.<br />
<br />
We've also got a tin of [https://www.rocol.com/products/rtd-compound Rocol RTD cutting compound], which is a thick paste. Its highly recommended for drilling and tapping steel (in the drill press or by hand), but as a paste, is less useful for general lathe work unless thinned to a fluid consistency, e.g. with paraffin or white spirits. OTOH its certainly worth trying for high speed facing steel as it is less likely to get flung off.<br />
<br />
== Cleaning and Maintenance ==<br />
Swarf is a significant cut hazard to the operator, especially stringy swarf from cutting steel. Never touch it bare-handed - always use a tool e.g. a brush, or a hook, or needle nose pliers for grabbing long swarf.<br />
<br />
* After use, brush all swarf off the toolholder, compound and cross slide etc. ways and leadscrew. Ian B has blocked off the opening at the headstock end of the rear splashguard (to try to keep swarf out of the motor), so one must sweep the swarf towards the open tailstock end and catch it in a dustpan or similar. Preferably, also thoroughly clean out the chip tray under the lathe, but at least sweep out visible swarf.<br />
* Wipe up any cutting fluid residue and re-lubricate affected sliding surfaces with way oil.<br />
* Do not solvent clean the chuck guard, as it will make the plastic brittle, or even craze it. Water with a little detergent is permissible for cleaning it, with the guard totally removed from the lathe.<br />
<br />
Before engaging the half-nuts for power feed/threading, check the leadscrew is clean! ''Best cleaned under power, with a toothbrush.'' <br />
<br />
'''Caution:''' The traverse gears behind the carriage handwheel are in an open-backed housing and tend to become packed with swarf! Swarf buildup here will result in jerky carriage movement. Clean out as much as you can with a toothbrush ...<br />
<br />
===Lack of lubrication and/or swarf or dirt build-up can be disastrous===<br />
* If using the change gears/power feed, lack of lubrication of the B-C stub shaft center pin or either leadscrew end bearing can result in seizure and immediate destruction of one or more gears in the gear train or worse. <br />
* Small pieces of swarf can get between the saddle and ways, or into the slides degrading accuracy, possibly permanently if hard swarf scores them, or jamming them. The carriage handwheel gears behind the apron are notorious for accumulating swarf, and swarf buildup on the leadscrew can prevent the half-nuts engaging properly, resulting in scrapped work, and possibly stripped half-nuts. <br />
* Metal swarf can get into the motor (''though Ian B has modified the rear chip catcher to reduce the risk)'' or into the control box via the leadscrew, and short-circuit stuff. At best it will blow the fuse and need a strip-down to clean it out, at worst it may require a replacement [https://www.amadeal.co.uk/acatalog/Speed-Control-Circuit-Board--12amp-AMA_SP_CJ18_SCB12.html#SID=12 speed controller] ''(currently £96)'' and/or [https://www.amadeal.co.uk/acatalog/550W-motor-for-CJ18A-Mini-Lathe-467.html#SID=240 motor] ''(currently £105)'' and possibly other electrical parts. We should probably fit a [https://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C3-Mini-Lathe-Spares/C3-256-Leadscrew-Grommet-Dustproof-Cover C3-256 Leadscrew Grommet] to keep swarf out of the control box, as it tends to drop onto the 'Filter' board which is mounted horizontally, below the leadscrew.<br />
* Grit from grinding, sanding etc. forms a grinding paste with the way oil, and will rapidly wear out the ways, saddle and slides. Keep grit off at all costs e.g. by covering the ways and slides during grinding/sanding operations, and if there's any chance grit has gotten where it shouldn't, clean and re-lubricate *BEFORE* moving the carriage or slides, then move the carriage and slides, wipe down where they were with a clean paper towel and check there's no remaining traces of dirt other than clean way oil on the paper towel. If it doesn't come clean when you re-lubricate and move it again, a full strip down may be required to solvent clean and relubricate the precision sliding surfaces.<br />
* Although a metalworking lathe *can* be used to turn hardwood, wood dust and small chips are extremely pernicious, as they get everywhere, even clinging to clean surfaces, are abrasive due to their silica content, and are hygroscopic, promoting rust. An even more thorough clean-up than after using abrasives is needed, immediately afterwards. Oily wood dust and fine wood chips in significant quantities are a fire hazard, even in the trash bin.<br />
<br />
===Lubrication===<br />
See section: "Lubrication" in LittleMachineShop.com "Mini Lathe User’s Guide" [[Ian_M's_Lathe_Notes#Manuals|(below)]]. As we usually only open two nights a week, in the table on page 16, Daily lubrication becomes Weekly and Weekly becomes Monthly.<br />
<br />
===General Maintenance===<br />
* The grubscrews holding the cross-slide and compound slide dials tend to loosen due to vibration and use of the dials. Keep them snugged up, but not so tight the dials cant be set without an Allen key.<br />
<br />
* The screws holding the cross-slide nut tend to work loose due to vibration. Crank the handle to and fro through the backlash and visually check there is no movement of the screw heads in their holes. If there is, see the [[#Excessive_cross-slide_backlash|notes below]].<br />
<br />
===Removing the Carriage===<br />
Its possible to remove the carriage from the bed for cleaning etc. without dismantling it. The only stop to its motion is the righthand leadscrew bearing.<br />
<br />
Start by removing the tailstock. Crank the carriage to the tailstock end then remove the leadscrew bearing (two screws and a nyloc nut on the leadscrew end). With the half-nuts open, hold the leadscrew centered in them and crank the carriage off the end of its rack, then slide it off the end of the bed.<br />
<br />
Refitting is the reverse of removal, except (if its gibs are correctly adjusted) the carriage will be very tight on the end of the bed ways so may be difficult to work onto the ways without a stack of blocks of wood or similar to support it at exactly the right height. The righthand leadscrew bearing must be refitted with the carriage as close as possible to it and the half-nuts firmly closed to support the leadscrew at the correct height to hold it in alignment while the screws are being tightened. The nyloc nut controls leadscrew end-play. Fully tighten it then back it off slightly till the leadscrew turns freely with its change gear removed.<br />
<br />
If the Apron has been off, refit it with the screws no more than lightly finger tight and only finally tighten them after checking lead screw engagement at both ends of the carriage travel and that the rack and pinion operates smoothly over the full travel.<br />
<br />
== Issues and Annoyances ==<br />
As of September 2023 - mostly resolved, apart from the spindle bearings and runout, the lathe is in better condition than it has been for a number of years.<br />
<br />
===Four Jaw Chuck has two jaws too tight===<br />
Fixed 27/10/2023: Two of the chuck jaws were tight in their slots, making precise adjustment difficult due to lack of 'feel'. Moving the jaws round the slots showed the problem mostly followed the jaw not the slot. The grooves in the opposite sides of the affected jaws that run in the chuck slots were slightly out of true, and the rails either side of the slots were slightly too thick towards the center. Due to the difficulty of seeing the high spots, after cleaning up and deburring the jaws didn't do enough to ease them, I decided to grind the top of the rails where they were binding. Several repetitions of spotting with Engineer's blue, grinding, then diamond filing the high spots has eased them enough. I cleaned everything, greased the jaw slides and screws, and refitted the studs so the chuck is now fit for service.<br />
<br />
''N.B. Don't move the jaws to a different slot - the formerly tight jaws *must* stay in the slots furthest from the makers mark.''<br />
<br />
===Excessive Runout===<br />
Mostly fixed 24/10/2022: I ground the chuck seating surface of the spindle nose (outside lip) to under half a thou runout. This also cleaned up several burrs. It would be possible to do better, but that would need good spindle bearings, and a more rigid toolpost grinder mount.<br />
<br />
Our spindle nose was damaged years ago by a person with little mechanical aptitude (who shall remain nameless) beating it up with a hammer mushrooming the spindle nose. We are getting several thousandths runout at the end of the MT3 bore, a MT3 to MT2 reducer sleeve in it runs visibly out of true, as does the spindle nose flange. When you put a chuck on it, the runout is magnified by the distance from the spindle nose. Ideally we would replace the spindle when we change the bearings but its £52 [https://www.amadeal.co.uk/acatalog/4-Spindle-Upgrade-Real-Bull-Mini-lathe-CJ18-series-AMA_SP_CJ18_003RB.html#SID=9 from Amadeal] and money is tight. It may well require more work after the bearing upgrade. Once good bearings are in, if we can borrow a decent MT3 arbour as a reference, we should consider skimming the bore.<br />
<br />
===Spindle bearings===<br />
* The spindle bearings appear to be close to worn out. They are notably noisy when running, and there appears to be more slop in the spindle than is desirable. There is notable resonance around 600 RPM, and surface finish of end faces is often poor. We have some ideas for possible replacement/upgrade, but it requires a major teardown.<br />
<br />
: The original bearings are allegedly 6206-2RS or 6206-ZZ deep groove ball bearings - 2RS codes rubber seals both sides and ZZ codes metal shields. Although the deep groove gives reasonable ability to withstand axial loads, the bearing balls point contact means they are vulnerable to [https://en.wikipedia.org/wiki/Brinelling brinelling] due to shock loading. The jammed on three jaw chuck didn't help this, as before we skimmed the spindle nose lip, it had to be driven off using a bar through the spindle bore, shock loading the bearings every time. Also even a minor 'crash' could have brinelled them due to eccentric shock loading, and the lathe has previously been crashed badly enough to need drive gear replacement. There are also issues with the 'approved' method of spindle and bearing removal from the headstock brinelling them, even if you don't abuse the spindle nose with a hammer!<br />
<br />
: A possible replacement is 30206 tapered roller bearings. The new bearings are slightly thicker so the plastic spindle spacer (15) needs to be machined to length to get the 45 tooth spur gear that drives the change gears laterally aligned with the tumbler gears. If a temporary replacement (3D printed?) is fitted, the lathe can be run (without power feed capability) so this can be done on the lathe after fitting the new bearings. As tapered roller bearings have line contact, they are significantly more resistant to brinelling.<br />
<br />
: ''See [[Talk:Ian_M%27s_Lathe_Notes]] for notes, links etc. for this upgrade.''<br />
<br />
===Motor stuttering===<br />
* Fixed 21/09/2023: The motor was running very erratically and it was very difficult to set a speed. Several loose connections were found in the control box, mostly loose female spades to the motor controller board, but also a dry jointed braking resistor on the 'Filter' board, and an inhibit wire completely off its terminal on the forward/reverse switch, making intermittent contact. After tightening and/or remaking all affected connections, it was much improved but still not right below 300 RPM. The remaining issues were due to poor wiper contact in the speed control pot, and stripping it, cleaning the track and contact ring and re-tensioning the contacts resulted in the motor now running smoothly over the full speed range. The speed is slow to settle, and while part of that is probably the lag in the digital tach, I suspect that the KBIC motor speed controller isn't properly tuned as it was (allegedly) previously replaced.<br />
<br />
===Drive belt slipping===<br />
* Fixed 28/9/2022: During testing the motor after the above issue, it was noted that the chuck could be stalled, slipping the drive belt, with not much torque. The drive belt was determined to be loose and a bit worn, but still in acceptable condition. <br />
<br />
: Access for servicing the belt requires removing the control box ''(2 spades to ZVR switch disconnect the supply, speed sensor and motor simply unplug from the 'filter board')'', the motor cover, chuck guard switch assembly + wiring cover, the change gear 'A' (drive) shaft carrier assembly, and the tumbler gear assembly. See https://youtu.be/EkxlIz01BdA for disassembly/reassembly, though on our lathe, the speed encoder ring on the spindle prevents the belt cover from being fully removed without disturbing the spindle nuts. There is enough room to work with it loose, but still trapped by the encoder ring. Also, unlike the video, if the 'jack' screws under the headstock are correctly adjusted, and the studs aren't excessively bent, there is no need to make custom studs. <br />
<br />
: It turns out that our lathe was missing the M6 hex headed jack screws that press the motor down to resist the belt tension, and the motor had cocked out of position at a severe angle. I know Ian B had had considerable trouble adjusting it after the motor fault back in October 2022, and I believe it had been getting slowly worse ever since. The jack screws were probably mistaken for headstock fixing bolts during disassembly after the crash that resulted in the metal Hi/Lo gears being fitted, then lost. The penny washers on the studs had dished, so I turned them over and backed them up with smaller washers and switched to Nyloc nuts so they cant back off due to vibration. N.B. There is a packing washer on the motor side on one of the studs, presumably so the shaft is true to the ways. Adjusting the motor is awkward to say the least. One has to slack the stud nuts off a lot, pry under its rear end to lift it enough to be parallel to the ways, snug the stud nuts, check alignment, then set the jack screws and their lock nuts to hold it there, and finally tighten the stud nuts. <br />
<br />
: Tension: According to Sieg, it should be possible to twist the belt 90° mid span with a light finger grip. Other sources say 1/32" - 3/32" deflection mid span with light finger pressure.<br />
<br />
===Speed display blanking===<br />
* The speed display has been intermittent, blanking and flashing 8888 and 0 at certain speeds for as long as I have been using the lathe. Finally on 18/07/2022 it failed completely, with no display. I removed the display module and bench tested it - the pins are labelled 5V GND PL PE, PE is frame ground and PL is a TTL level pulse from the speed sensor - confirming that it was in good working order. My suspicions then turned to its power supply on the 'Filter' board. With both the sensor and display unplugged, the 5V rail was found to have a only a couple of volts, but the unreg DC was 17V and stable. Replacing the 78L05 5V regulator restored the 5V rail and normal operation.<br />
<br />
: ''I conclude its been failing for a while with high load current due to speeds with more lit segments causing it to drop out, resetting the speed display, causing it to blank, lowering the current enough for the regulator to recover, then the display MCU lamp tests (8888) then re-acquires the speed, repeating ad-nauseum till the speed is changed. I don't like the design as the high input voltage results in excessive dissipation.'' <br />
<br />
: ''ToDo: If it fails again, bench test display to measure its worst case current consumption, then fit an appropriate dropper resistor to reduce the 78L05 dissipation.''<br />
<br />
===Quill spinning when drilling===<br />
* The quill was tending to spin while drilling because its anti-rotation pin (a M5 dog tip setscrew) was sheered. I've removed the debris, aligned the scale with the top of the tailstock and fitted a longer M5 dog-tip setscrew to replace it, with a nut to lock it at the correct height. N.B. the pin isn't that 'meaty' so if using big drills in tough metals, to prevent shearing it, it should be backed out so the quill can be turned by hand and unwanted rotation controlled by being quick with the quill lock if it starts to spin, or even using a close fitting rod in one of the chuck key holes with plastic tube over it to protect the ways. <br />
: ''If the screw sheers again, the quill will need to be removed and the tailstock taken off the lathe so the sheered tip can be shaken out, and if the setscrew is difficult to remove it probably means the threads are mangled where it sheered. Try driving it right through with the quill out.''<br />
<br />
===Sloppy quick change toolpost locking mechanism===<br />
* Once the dovetail clamp screw was slackened, there was nothing preventing the dovetail twisting or cocking significantly, and friction with the toolholder made it tend to do so, making toolholder insertion and removal more difficult unless the clamping screw was backed off excessively. I added a compression spring around the clamp screw inside the toolpost to push the dovetail outwards so it mostly retains alignment when open, allowing toolholders to slide on or off cleanly with far less screw slackening.<br />
<br />
===Leadscrew rubbing===<br />
* The leadscrew shaft is rubbing on the insulating separator inside the control box. Unfortunately the corner of the relay on the Filter Control Board (#160) doesn't allow enough clearance. Although the friction isn't much of a problem at high reduction ratios, e.g. 16:1 power feed, it increases the stress on the change gear train, and may be problematic when threading at feeds above 1:1. ''Possibly pack out the control box mountings by a couple of mm.'' <br />
<br />
===High/Low lever backwards!===<br />
* The high-low drive gear selector behind the headstock is incorrectly labelled and differs from the manual: low gear (which we normally use) is with the lever towards the tailstock. ''I suspect that the gears in the headstock were refitted the wrong way round when it was upgraded to metal gears.''<br />
<br />
: ''ToDo: Get it reassembled the right way round during the spindle bearing upgrade!''<br />
<br />
===Carriage lock fouls top slide===<br />
* The T handscrew has been replaced with a M5 hex headed bolt, to permit access when the top slide is over it. An 1/4" drive 8mm socket is usually left on it, but needs to be removed when the full cross slide travel is needed. The small (4 jaw) chuck key is near enough 1/4" to use for it. If you need to (un)lock it while the compound is over it, you'll need an 8mm spanner. ''The [https://www.amadeal.co.uk/acatalog/Mini-Lathe-Carriage-Lock-463.html Amadeal lock screw] is in the spares tin as it was too high and fouled the compound slide.''<br />
<br />
===Tailstock locking lever loose===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock - See full image for key to screws]]<br />
* Diagnosed and fixed 10/1/2023 - In the base of the upper section of the tailstock, there are two dog tip set screws that engage with locating grooves in the counter-rotating shafts carrying the eccentric locking cams. They'd backed off, probably due to vibration. They need to be tightened till they bottom out in the groove, making sure they are '''in''' the groove, backed off half a turn so the shafts can turn easily, and locked in place. There's no facility to do so, so reassemble with weak threadlocker. Unfortunately to get to them you have to remove the tailstock base slide, which is held on by the pressure of four adjusting grub screws, which all need backing off, and one socket headed bolt from underneath so full tailstock realignment is required after reassembly, which even for a rough alignment is tedious.<br />
: <s>The tailstock locking lever is loose and can be pulled out on its axis. It works OK when fully pushed home but needs investigating. ''I tightened the grub screw as the lever was coming off its shaft, but the whole shaft pushes/pulls in and out. It works OK fully pushed in, but it seems something that is meant to retain it has failed inside the tailstock base.</s><br />
<br />
===Gear alignment issues===<br />
* Change gear alignment is poor. I've currently got a gapped washer (to clear the key) packing out the A shaft so the gears line up, but this reduces the key's engagement so is problematic due to the high loading if the gears are set up for coarser threads. <s>Also I need to turn down some penny washers to slightly less than the root diameter of the metal 20T pinions, as gear retaining washers.</s> ''The gear retaining washers for A gear and B-C stub shaft are now done, turned down to slightly under 16 mm dia. Spares in the change gear tin. ToDo: The D (leadscrew) washer requires a larger center hole, so make two more with that hole.'' <br />
<br />
===Saddle gibs loose===<br />
* Fixed 11/04/2023: I took the apron off for access (and to clean the carriage handwheel gears), and found the front sheer plate screws were completely loose. I've snugged them up some and set the opposing grub screws and got a lot of the slop out. I've re-checked the front ones, and taken up the slop in the rear ones - Unfortunately it wasn't possible to get carriage movement to have an even 'feel' over its whole travel, and its noticeably tighter near the tailstock. If light hand pressure on the side of the unlocked carriage can cause movement (with the half-nuts open), its time to readjust them again, though it should be possible to move the carriage with a firm push. <s>The saddle gibs (actually the sheer plates) were too loose, to the point that engaging a slightly stiff threading dial could cause it to self-feed, an obvious crash hazard if working near the chuck or a step in the work.</s><br />
<br />
''N.B. the lefthand front opposing grubscrew is short, (fully recessed) and unlike the others does *NOT* have a locking nut as it must clear the traverse pinion. A wrap of PTFE tape provides enough friction to keep it in place, though possibly a bit of nylon fishing line down its hole would be better.''<br />
<br />
===Excessive cross-slide backlash===<br />
* ''Fixed 21/11/2023.'' Originally, back in October 2023, The cross-slide screw had excessive backlash (nearly three turns), which increases the risk of loosing track of the cut depth when cutting steps, and during threading operations. If you ended up off by a turn too far in, a crash would be the most likely outcome.<br />
: The original excessive backlash was traced to loose cross-slide screw nut mountings. The nut has two socket headed cap screws pulling up, one either end, accessible from the top of the cross-slide, which control the tilt of the nut to take up backlash in the nut, and an opposing grub screw pressing down on the center of the nut to make it longitudinally rigid. Snugging up the grub screw reduced the backlash to 10 divisions or so, or 0.25 mm. A year later, the backlash had increased to one turn due to the cross-slide nut mounting screws working loose again.<br />
<br />
: 07/11/2023: I investigated further: It is difficult to get the cross-slide nut aligned correctly as it must be at the same height as the screw which is constrained by the bearing surfaces in the bracket. With the cross-slide almost at the front limit of its travel, I removed the screw and set the nut as level as possible and visually centered in the bore, then re-fitted the bracket and screw, then adjusted the tilt till it turned freely through the backlash. I then tilted it up at the front till some drag was felt to minimise the backlash and tightened the screws to lock it in place balancing them to maintain the same feel as I tightened them. The result was 7 divisions of backlash, acceptable but not great. During normal turning operations, the load on the nut is tension on the front screw and pressure on the grubscrew, so if it slackens again due to vibration from chatter, odds are it will be the rear screw that's loosened.<br />
<br />
: 16/11/2023 - 21/11/2023: The backlash had crept back up to 11 divisions (0.275 mm). We don't have any >14 mm brass stock (or even near that) so I tried making the shim washer out of aluminium. I was shooting for 0.24 mm but due to poor technique got 0.28 mm. No good - locked solid. I lapped it down and tried it till I got it down to 0.20 mm which gave about 3 divisions backlash - good enough, but the screw was too tight due to the shim washer not being bevelled at its outer edge resulting in it cupping in its seat. Filing a bevel round the OD and re-lapping it resulted in a 3 - 4 divisions of backlash. Its a little mushy due to the washer having been kinked removing it, so ideally a new (brass) washer should be made. <br />
<br />
* Further reduction of backlash: https://youtu.be/Wu_tI29JL2Y?t=163 <br />
: Brass tinned with Pb-free solder to form a white metal bearing surface should work at least as well as the bronze used in the video. The shim washer needs to be 10.2mm ID, with a full thickness bevel on a 14 mm OD. It isn't necessary to remove the lead screw from the cross slide, as the washer can be fitted in-situ with only the bracket removed.<br />
<br />
===3 Jaw chuck didn't mount properly===<br />
* Fixed 7/4/2023 by grinding the spindle nose lip. The three jaw chuck can now be installed and removed by hand with no hammering. A test bar in it now has only 2 thou runout (TIR) at the chuck.<br />
: <s>The three jaw chuck and the faceplate aren't seating properly on the spindle nose. Its too tight on the register diameter of the lip. This results in grossly excessive runout, and also makes this chuck and the faceplate a PITA to fit or remove.</s><br />
: ''The spindle nose had been abused with a hammer (before my time) which mushroomed it and may have brinelled its bearings. See '''Excessive Runout''' and '''Spindle bearings''' above.''<br />
<br />
== Manuals, Books and other resources ==<br />
=== Manuals ===<br />
The [https://wiki.richmondmakerlabs.uk/images/a/a3/Lathe_InductionNotes.pdf RML CJ18A Mini-Lathe Induction Notes]. Your mandatory Lathe Induction will cover most of this but its good to be able to refer back to it. Also see [[:File:Lathe Induction Bushing.pdf|Lathe Induction Bushing]], which you will make during your induction, to introduce the four key lathe skills: facing, turning, drilling, and parting off. <br />
<br />
Official [https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Amadeal CJ18A Manual], or paper copy (less complete) kept on shelf above lathe.<br />
<br />
The [https://www.chesterhobbystore.com/wp-content/uploads/2022/11/Conquest-Super-Lathe.pdf Conquest Super Lathe manual] is considerably better than the Amadeal manual and is for a near-identical machine.<br />
<br />
The [https://littlemachineshop.com/images/gallery/info/minilatheusersguide.pdf Mini Lathe User’s Guide] from LittleMachineShop.com is even more comprehensive, going into its usage in some detail, with a proper TOC, and covers both US and Metric versions of Realbull Mini-lathes. ''The only fly in the ointment is the threading section assumes a US lead screw so change gear selections and threading dial divisions will not be correct for our lathe.''<br />
<br />
[https://www.arceurotrade.co.uk/machineguides/C3-Mini-Lathe-Dismantling-and-Reassembly-Guide.pdf Sieg C3 Mini-lathe Dismantling and Reassembly Guide] "A picture story book to help you dismantle and reassemble your Sieg C3 Mini-Lathe" ''It is similar enough to ours to serve as a maintenance guide, except for the electronics, spindle drive and other headstock innards.<br />
<br />
The motor controller is a clone of a [https://acim.nidec.com/drives/kbelectronics/-/media/kbelectronics/documents/dc-drives/manuals/kbic_manual.ashx?la=en KBIC® SCR DC Motor Speed Control]<br />
<br />
=== Books ===<br />
'''Metal Turning on the Lathe''', by David A Clark, Crowood Metalworking Guides, ISBN-13: 978-1847975232 [https://www.amazon.co.uk/gp/product/B00E78RKIG Kindle Edition (£8.99)]. ''A 'free' epub can be googled for, *NOT* linked here due to dubious legality.''<br />
<br />
'''[https://archive.org/details/03screwcuttinginthelathe Screwcutting In The Lathe]''', by Martin Cleeve (a pen-name of Kenneth C Hart), Workshop Practice series #3, ISBN-13: 9780852428382<br />
<br />
'''[https://archive.org/details/15workholdinginthelathe Workholding in the Lathe]''', by 'Tubal Cain' (a pen-name of Tom Walsh), Workshop Practice series #15, Argus Books, ISBN-10: 0852429088<br />
<br />
'''[https://archive.org/details/20metalworkandmachininghintsandtips Metalwork and Machining Hints and Tips]''', by Ian Bradley, Workshop Practice series #20, ISBN-13: 9780852429471<br />
<br />
'''[https://archive.org/details/38toolandcuttersharpening Tool and Cutter Sharpening]''', by Harold Hall, Workshop Practice series #38, ISBN-13: 9781854862419<br />
<br />
'''[https://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpaperT204.pdf Cutting Fluids]''', by EC Bingham, NIST Tech. Paper No. 204, 1921<br />
<br />
=== WWW resources ===<br />
==== Mini-lathe Specific ====<br />
There's a *LOT* of mini-lathe info online. Notable sites include:<br />
* http://www.mini-lathe.com/ - A major Realbull/Sieg mini-lathe resource.<br />
* http://mikesworkshop.weebly.com/lathe-modifications.html - many mods including carriage DRO autostop, and variable speed leadscrew motor drive, cross-slide motor drive, etc. He also has a page with a bunch of accessories, toolholders etc. - http://mikesworkshop.weebly.com/lathe-accessories-and-tooling.html<br />
* http://andysmachines.weebly.com/variable-speed-controls.html - Scroll down to the 'UPDATE' section for the schematic of a very similar SCR speed control board. It also has the schematic for an earlier version of the Auxiliary Control Board (aka: 'Filter' board).<br />
* https://www.youtube.com/watch?v=WbJM9ooveo8 - A video tour of a very very similar mini-lathe. Significant differences: ours has a 4" longer bed, a quick change toolpost, a different tailstock, no DRO (apart from basic spindle speed, so skip 16:12 to 28:50 in the video), larger chucks and a carriage lock.<br />
<br />
==== Forums ====<br />
''with publicly accessible archives''<br />
* https://groups.io/g/7x12MiniLathe - Mini-lathe specific, active<br />
* https://www.hobby-machinist.com/forums/mini-lathe-mini-mill-information.220/ - active<br />
==== Youtube Playlists & Videos ====<br />
* Blondihacks: [https://www.youtube.com/playlist?list=PLY67-4BrEae9Ad91LPRIhcLJM9fO-HJyN Lathe Skills] (playlist) - "This is an educational series to help you learn to use your metal lathe. Watch them in order for best results! Satisfaction not guaranteed, especially if you're a cranky sort of person."<br />
* Frank Hoose (Minilathe.com) has a couple of relevant Youtube playlists:<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn7ON0jGM5UbM-KZDT56MOIp Mini Lathe Operations]<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn4nGRZaVq3wTOlvZNOmdAZ2 Mini Lathe Overview]<br />
<br />
==== General Machining ====<br />
* https://www.machiningdoctor.com/ - "THE #1 MACHINING TECHNICAL HUB"<br />
<br />
==Projects==<br />
[[File:VESA mount.jpg|thumb|Machined VESA mounting plate (left) and plate from Dell monitor stand it must match (right). The translucent washer shows the size of the original center hole.]]<br />
* My first faceplate project was boring out the center hole in a VESA mounting plate to adapt it to fit onto a surplus Dell 1708FP monitor stand. The part was centered using the tailstock dead center engaging with its original center hole. I clamped the part with studs and penny washers on the driving side of two opposite corners, with cap screws in the next slot round to trap the corners under the clamping washers, then withdrew the tailstock and dead center. After machining out the bore, I used the tip of the tool, rotating the chuck by hand, to scribe a circle for laying out the bolt holes. I finished off laying out and drilling the bolt and locating holes by hand at home, fitted it to the stand, and mounted the 2nd hand LG 24" widescreen monitor.<br />
<br />
* Another ultimately unsuccessful project was fly cutting aluminum flat bar to thickness to make custom shims for the set of carbide insert tools, for the four way toolpost. The 8 mm shank tools need ~2.5 mm shim stacks, and the 6 mm shank tools need ~4.5 mm shim stacks. Ideally I'd machine single shims, but the only stock I've got handy cleans up to only 3.2mm, and some fine shimming may be needed to fine-tune the tool height.<br />
<br />
: After sorting out the clamps so they were no longer twisting the aluminum flat bar stock, and switching to the short 45° turning SCMT06204 insert tool in the four way toolpost, to improve rigidity and get a well controlled tip radius, the finish was much improved. I'm still having problems getting an even thickness and am getting approx. 0.05mm variation, I suspect due to the aluminium bar stock distorting due to internal stresses as its surface is cut away. ''ToDo: try supergluing the stock to the faceplate before clamping to further reduce chatter and stop the warping.''<br />
: Looking back on this project a year later, its fairly obvious that the thickness variation was probably due to faceplate surface runout due to the damaged spindle nose.<br />
<br />
* Raphael has been working on a steel rocket nozzle with some assistance from myself. We have set up the rough cut chunk of ~ 50mm steel bar, faced both ends (to 50mm length) and turned the OD to 49mm to clean it up. Its going to need through drilling, probably some boring, and quite a bit of detail work on the OD. It will then need to be transferred to a jig in the drill press vice to allow a pattern of angled traverse holes to be drilled with acceptable accuracy.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_Lathe_Notes&diff=17624Ian M's Lathe Notes2024-02-18T13:11:58Z<p>IanM: /* Manuals */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br />
<br />
''Currently these notes are semi-organized and non-authoritative. As I become more experienced with the RML CJ18A mini-lathe, I'm cleaning up, extending and reorganising them. Some lathe operating experience is assumed. If in doubt, '''*ASK*''' me, Andy H<sup>*</sup> , Jonathan H or another experienced minilathe operator!<br />
<br />
''* Andy H should be asked (for an authoritative answer) any questions involving RML usage policies or acquiring tooling or materials through RML.''<br />
<br />
== The Lathe ==<br />
Our Facilities page [[Facilities#Lathe|has]]:<br />
<blockquote><br />
'''Lathe'''<br />
[[File: Lathe2.jpg |200px|right | Lathe]]<br />
In the kitchen. <br />
<br />
Marked as a CJ18A Mini-Lathe from [[https://www.amadeal.co.uk/acatalog/CJ18A-Mini-Lathe-7x14-Machine-100mm-3jaw-Metric-With-Metal-Gears-AMA_LA_CJ18_M_3_MGRB.html Amadeal]]<br />
[[https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Manual]] <br />
<br />
[[Media:Lathe InductionNotes.pdf| Induction Document]]<br />
<br />
Possible upgrades:<br />
*https://www.youtube.com/watch?v=GwT-JQLbNPA<br />
<br />
''Please do not use the lathe until you have received induction'' <br />
<br clear=all><br />
</blockquote><br />
Its a Chinese import 7x14 mini-lathe. The 7x14 refers to the maximum diameter and length of work, in inches and is only a theoretical measure of the working envelope as you loose length to the chuck + any tailstock tooling, and the diameter is over the bed, not the cross-slide. See actual specifications below. <br />
<br />
Most if not all Chinese 7x10 to 7x16 mini-lathes seem to be remarkably similar (not uncommon with Chinese products due to [https://www.bunniestudios.com/blog/?p=284 Shanzhai (山寨)] )<br />
and the OEM of our Amadeal CJ18A Mini-Lathe was probably [https://www.made-in-china.com/showroom/cheap-lathe Yangzhou Realbull Machinery Co. Ltd]. Very similar lathes are also made by [https://www.siegind.com/lathe-machine.html Sieg], but their lathes tend to be slightly less sophisticated than the equivalent Realbull models.<br />
<br />
''N.B. Many Sieg parts are known to have slight but critical differences from Realbull parts, so '''DON'T''' order Sieg spares for a Realbull lathe!<br />
<br />
== Key Specifications ==<br />
Amadeal says the CJ18A Mini-Lathe is a 7x14 model with:<br />
<blockquote><br />
* Power 550 W<br />
* Distance between centres : 350 mm<br />
* Swing Over Bed: 180 mm<br />
* Swing Over Cross Slide: 110 mm<br />
* Taper: MT3<br />
* Tailstock Taper: MT2<br />
* Chuck diameter: 100 mm<br />
* Spindle Speed: 50 - 2500 rpm ''(with digital readout)''<br />
* Spindle Bore: 20 mm<br />
* Cross slide Travel: 65 mm<br />
* Range of Metric Threads: 0.5 - 2.5mm.<br />
</blockquote><br />
* The lead screw is metric, pitch 1.5 mm.<br />
* The spindle center is 90.6 mm above the flat of the bed (measured).<br />
<br />
Even though the compound and cross slide handwheels appear to be calibrated in thousandths of an inch, as ours is a metric machine, they only approximate that. One turn of a slide handwheel is 1mm advance, and they have 40 divisions, so each division is 0.025 mm, (approx. 0.984 [https://en.wikipedia.org/wiki/Thousandth_of_an_inch thou]). Similarly, the tailstock quill advances 1.25 mm per handwheel turn, which has 50 division dial, giving the same 0.025 mm divisions, but only 4 turns per 5 mm. The carriage handwheel is awkward - it moves approx. 19.2 mm per turn, and doesn't have a dial scale.<br />
<br />
== Notable Accessories ==<br />
We have:<br />
* [https://www.amadeal.co.uk/acatalog/160mm-Face-Plate-for-the-4-Mini-lathe-AMA_AC_CJ18A_FP160RB.html#SID=129 160 mm (6 1/4") Faceplate]<br />
* 100 mm (4") three jaw self-centering chuck (OEM standard) 22.5mm bore, with inside and outside jaw sets<br />
* 100 mm (4") four jaw (independent) chuck with reversible jaws (8 TPI screws)<br />
* Tailstock drill chuck (max. 13 mm dia.)<br />
* Live center for tailstock (+ OEM fixed center) <br />
* Four way Tool Post (OEM Standard)<br />
* [https://www.amadeal.co.uk/acatalog/Quick_Change_Tool_Post_for_the_mini-lathe.html Quick Change Tool Post] + 3 tool holders<br />
* [https://www.amadeal.co.uk/acatalog/Fixed-Steady-for-Mini-Lathes-AMA_AC_CJ18A_FSRB.html#SID=145 Fixed Steady Rest]<br />
* [https://www.amadeal.co.uk/acatalog/Travelling-Rest-for-Mini-Lathes-AMA_AC_CJ18_TSRB.html#SID=144 Travelling Steady Rest]<br />
<br />
''You'll find all of the above on the shelf above the lathe, with the accessories in the wooden box, apart from the steadies, which live next to it. Change gears, spare parts, and most cutting tool tips/blanks are in labelled white rectangular tins behind the lathe.''<br />
=== Measuring Tools ===<br />
We have:<br />
* Various dial indicators - the one with the adjustable magnetic base stand is the most convenient for most lathe setup work.<br />
* 25mm micrometer (in little grey case)<br />
* Grey case containing set of measurement tools including dial calipers, micrometer, steel rule (metric & inch), engineers square, and a fish-tail gauge<br />
<br />
''We currently lack''<br />
* ''A tool height setting gauge''<br />
<br />
=== Hand Tools ===<br />
Some common tools needed for normal use are kept with the lathe, in or attached to the wooden accessories box:<br />
* 2 mm Allen key - adjusting cross-slide and compound gibs<br />
* 4 mm Allen key - quick change toolholder tool clamping screws + height adjust, tightening dials<br />
* 5 mm Allen key - four way toolpost tool clamping screws, engaging/disengaging threading indicator<br />
* 6 mm Allen key - locking/unlocking quick change toolholder<br />
* 8 mm spanner - locking carriage when 8 mm socket can't be used, locking gib adjuster nuts <br />
* 13 mm spanner - changing chucks, locking steady rest jaws<br />
* Very long needle nose pliers - for grabbing swarf safely, holding one end of emery cloth safely so you can keep your fingers away from the jaws, and extricating small objects from awkward places.<br />
<br />
== Change Gears ==<br />
[[File:BC puller 1.jpg|thumb|Custom puller for B-C stub shaft]] [[File:BC puller 2.jpg|thumb|Pulling the B-C stub shaft]]<br />
See "Conquest Super Lathe" manual ([[#Manuals|below]]), section '''4.7 Change Gears''', PDF pages 28-29, but see below for mesh adjustment. The LittleMachineShop.com "Mini Lathe User’s Guide" (also below) section '''Threading''' gives a far better explanation, with pictures and diagrams, but its for a lathe with a US 1/16 inch pitch leadscrew, not a metric 1.5 mm pitch one like ours, so you *MUST* ignore all the tables in that section, replacing them with metric mini-lathe (with 1.5 mm pitch leadscrew) equivalents. <br />
<br />
We have the following tooth count gears: 20,20, 30, 35, 40,40, 45, 50,50, 60,60, 80,80<br />
which consist of the OEM power feed gears + the metric change gear set. Apart from the metal 20 tooth pinions, they are all plastic, probably Delrin if the molded in 'POM' marking can be trusted, but possibly plain Nylon 6, and are metric Module 1.<br />
<br />
If we wanted to add the capability to cut US/Imperial threads we'd need to buy additional 55, 57 and 65 tooth gears, and possibly a 21 tooth metal pinion.<br />
<br />
CGTK's [https://www.cgtk.co.uk/metalwork/calculators/changegears/minilathe?gears1=20,20,30,35,40,40,45&gears2=50,50,60,60,80,80&gears3= Change Gear Calculator] ''(link preloaded with our gear list)'' is useful if you don't want to calculate the ratios from first principles. Not all suggested combos will physically fit.<br />
<br />
* Take care *NOT* to loose the keys in the A and D shaft keyways - turn each shaft till the keyway is up before removing the gear. <br />
* The B and C gears are coupled by a hollow stub shaft (with an integral key), which is so tight in the gears it has to be pressed or driven out - I've made a puller just for this task, kept in the change gears tin.<br />
* The center of the B-C stub shaft *MUST* be lubricated where it runs on its pin on the change gear banjo bracket, with grease or heavy oil. ''Seizure of the stub shaft due to running dry is a frequent cause of catastrophic mini-lathe geartrain failures!''<br />
* Don't get oil on the change gears as it can cause plastic gears to crack. Only PTFE drylube or plastic compatible white grease should be used on their teeth. <br />
* Adjust the B-C pin position in the straight slot first to set the C to D gear mesh, tighten its nut, then swing the whole banjo about the D shaft boss to set the A to B mesh, and finally tighten the banjo clamping nut.<br />
* Check both gear meshes have running clearance by turning the chuck by hand enough to complete one full turn of the leadscrew, and by attempting to turn the intermediate gear(s) to assess backlash, If excessive resistance is felt or if there's significant backlash, readjust the gears. If you have difficulty judging the mesh, a strip of 80 gsm copier paper (approx. 0.1 mm thick) wound into the meshing teeth before tightening the stud or banjo will give appropriate clearance once removed. Once setup, check the gears run quietly under power.<br />
* If the sum of the tooth counts C+D is the same as for the ones you just removed and they were correctly meshed, you don't need to move the stub shaft pin. If A+B is <u>also</u> the same, you don't need to move the banjo. e.g. If it was set up for 16:1 reduction power feed, 1 mm (40:60 - 50:50) for M6 and 1.5 mm (e.g. 40:60:40) for M10 pitches can thus be achieved by only swapping gears. <br />
<br />
''The change gears, puller, etc. and a box spanner for the banjo nut are kept in a white rectangular tin behind the lathe.''<br />
<br />
=== Power Feed ===<br />
When used for turning with power feed, the change gears should be set for a 16:1 reduction (A:20 : B:80 - C:20 : D:80) using the pair of small metal 20 tooth pinions and the 80 tooth plastic gears (largest in set), for a feed of 0.09375 mm per turn (1.5 mm/16). Unless continuing your threading project the next session, please re-fit the 16:1 power feed set after threading so the power feed is ready for use. <br />
<br />
* *ALWAYS* leave the feed direction selector lever in its neutral (no feed) position, and the half-nuts open after use.<br />
* *ALWAYS* check the carriage lock is disengaged before engaging power feed. Unlock the carriage after use. <br />
<br />
=== Threading Dial ===<br />
The threading dial is an aid to re-engaging the half-nuts at the right moment so the tool will retrace its previous path cutting deeper, rather than offsetting axially some fraction of the thread pitch and ruining your work. Its based on the concept of the lowest integer multiples of the leadscrew and thread ''(being cut)'' pitches that exactly match, but for mechanical simplicity it only covers certain selected multiples of the leadscrew pitch.<br />
<br />
We have a choice of three pinion gears:<br />
{| class=wikitable<br />
|+ Threading dial Pinion Gears<br />
|-<br />
! Teeth !! Colour Dot !! Usable lines !! OD gear !! Dist. per turn<br />
|-<br />
| 14 || Red || 1,7 || 7.51 mm || 21 mm<br />
|-<br />
| 15 || Orange || 1,5,9 || 8.05 mm || 22.5 mm<br />
|-<br />
| 16 || Green || 1,4,7,10 || 8.37 mm || 24 mm (2 mm/div)<br />
|}<br />
They are now colour coded, with a paint dot on the gear end face ''(the only non-wear surface)''. The 16 tooth one is normally left on the lathe, but disengaged when not threading to minimise wear on the lead screw. The others are kept in the Change Gear tin.<br />
<br />
There's a threading dial 'pickup' calculator here: https://www.cgtk.co.uk/metalwork/calculators/threaddialindicator <br />
<br />
Initially select ''Lathe:'' '''Custom''', and enter the following below:<br />
* ''Units:'' '''Metric'''<br />
* ''Lead Screw Pitch (mm):'' '''1.5'''<br />
* ''Thread Dial Indicator Gear Teeth:'' '''16,15,14''' <br />
* ''Lines on Thread Dial Indicator:'' '''12''' <br />
* ''Line Marking:'' '''Every Line Numbered'''<br />
Note the teeth list is entered in reverse order so the resulting table highlights any required pinion changes.<br />
<br />
N.B. The dial is only friction clamped to the pinion by its center screw. If you have any reason to suspect it may not be properly aligned: <br />
# With the power off and the carriage unlocked, engage the feed direction lever upwards. You'll probably need to turn the chuck by hand to get it to engage.<br />
# If the threading indicator isn't already engaged, loosen the threading dial support block bolt, pivot the block to engage the pinion with the leadscrew and retighten the bolt.<br />
# Engage the half nuts, again turning the chuck by hand till they drop in. <br />
# Turn the chuck a couple of turns, top towards you to take up any backlash, then lock the carriage, taking care not to push it left while locking it.<br />
# Loosen the screw securing the dial to the pinion.<br />
# Align the '1' line of the dial with the index line, by rotating the dial clockwise, then retighten the screw.<br />
# Don't forget to disengage half-nuts and unlock the carriage!<br />
<br />
The above instructions should result in the half-nuts engaging cleanly when exactly on any valid line when threading towards the headstock. If it is required to thread away from the headstock, there will be a slight offset from the line due to backlash between the spindle gear and leadscrew, so engage slightly early.<br />
<br />
Changing the pinion:<br />
# Loosen the threading dial support block bolt and disengage from the leadscrew.<br />
# Undo dial center screw, and remove it and the dial, dropping the old pinion out the bottom.<br />
# Oil the shaft of the new pinion with a drop of light oil and insert it from below, gear end down.<br />
# Refit dial and screw.<br />
# Check the dial and pinion turn freely with minimal resistance.<br />
# Align as above.<br />
<br />
== Tailstock and Steadies ==<br />
These are mostly used to support long work ''(long with respect to its diameter)'' to improve rigidity, increasing accuracy and reducing chatter. The Tailstock quill is also used with a drill chuck for drilling.<br />
=== Tailstock ===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock base]]<br />
The tailstock can be offset to turn shallow tapers between centers. We don't currently have the accessories to turn between centers, namely <s>a MT3 dead center for the spindle, or</s> any drive dogs for the work. Also realigning the tailstock after turning a taper can be a PITA. The photo shows the tailstock adjusting screw locations ''(C - Lateral, and D - Skew)'' and the block on the baseplate they engage with. Adjustments can only take effect when the tailstock locking lever is eased to take the pressure off the baseplate. As we don't have a MT3 center, one has to turn a fresh point on a test workpiece for a rough tailstock alignment reference. Fine alignment, to avoid inadvertent taper turning, can be done by mounting a long precision ground bar between the chuck (or preferably a center in the spindle), and a dead center in the tailstock and sweeping it with a dial indicator on the carriage. Finally a test cut should be taken at either end of a bar between centers, and the diameters checked with a micrometer. Assuming the bed has previously been properly levelled and shimmed to take out twist ''(not the case at RML as we don't have it bolted down)'', any remaining difference in diameter will be double the tailstock offset, smaller at the tailstock being offset towards the front. Fine adjustment cant be achieved by jacking with the screws, its best to ease the adjusting screws, bump the tailstock into alignment then take up the screws again, checking the alignment is maintained when the tailstock is unlocked and relocked. There is no vertical adjustment, though shims can be added between the tailstock and its base.<br />
<br />
==== Tailstock Quill ====<br />
There is a metric/imperial scale on the top of the quill, read against the end of the tailstock, for depth measurement when drilling. The tailstock quill has a 1.25 mm pitch thread and a 50 division dial. Each division is therefore 0.025 mm, and it only takes 4 full turns of the handwheel to move the quill 5 mm. <br />
<br />
To eject MT2 taper tooling and centers from the tailstock, wind the quill all the way in.<br />
<br />
N.B. The quill anti-rotation pin (dog-tip setscrew + locking nut in top of tailstock near to the quill lock) is only M5. It will sheer if a large diameter drill jams in the work. Please back it out clear of its keyway if using large drills, and use alternative methods of preventing chuck rotation. To re-engage it, crank the quill out till you can see the keyway, align it with the screw and screw in the screw till it gently bottoms out, then back it off a quarter turn. Try twisting the quill to check its properly engaged, then tighten the locking nut gently to hold the screw in position clear of the bottom of the keyway.<br />
<br />
=== Steady Rests ===<br />
We have two, both with brass tips that must be kept lubricated during use.<br />
<br />
The fixed steady mounts on the ways, and is most useful when turning longer work that wont fit through the spindle bore. Adjustment is critical, and the surface the tips run on must be smooth and concentric, as any misalignment that forces the work off center will result in the work wobbling in the chuck, marring it, with a high risk of it becoming un-chucked, which can be dangerous at speed.<br />
<br />
The travelling steady mounts to the headstock side of the carriage to locally resist the deflection of thin long work, due to the cutting forces. It only has two tips, to resist climb, and deflection away from the tool, and requires readjustment after every cutting pass.<br />
<br />
== Tooling and Tool Holders ==<br />
'''Key dimensional data:'''<br />
* The quick change holders accept up to 10 mm shank tools. <br />
* The four way toolpost has 50 mm long sides, a seat width of 15 mm and can clamp tools of up to 5/8" (15.875 mm) shank ''(check this)'', but the slot base is only 10.4 mm below the spindle center so cannot be used with >10 mm shank tooling unless it has a dropped tip. Large tooling with a centered tip is also problematic as you run out of height above the shank when trying to shim to match the spindle center height. <br />
<br />
===Quick Change Toolpost===<br />
I've got the quick change toolpost and toolholders setup for mostly easy use. The three toolholders came with cantilever height setting arms which historically haven't been installed as the supplied fixing screws were too short. That's all now sorted out and a HSS RH turning tool and a HSS hand-ground grooving/parting-off tool are now mounted in two of the holders and set to height. The third is kept free for other tools. <br />
<br />
The quick change toolpost has been modified with a spring to press the dovetail clamp outwards and help stop it twisting or flopping about to ease toolholder fitting and removal. The dovetail clamp (socket headed screw on toolpost side opposite dovetail) feels a bit stiffer than before, but will take less than half a turn to go from open (with the toolholder lifting out or dropping in easily) to fully clamped. As there is so much less clearance in the open position you should no longer need to wiggle the toolholder while clamping it to get a consistent height. If the dovetail clamp ever gets misaligned, twist it straight by eye, slacken off a bit further than usual to get a toolholder on, clamp it to align the dovetail then release, reseat the toolholder and re-clamp to ensure its at its preset height. You cant adjust the height by 'jacking' with the height screw due to its offset leverage. Instead, back off the height screw and hold the toolholder at the desired height while locking the dovetail clamp, then adjust the height screw (and locking nut) to hold it there, then check it doesnt change height significantly when you unclamp and reclamp the dovetail. <br />
<br />
Unfortunately the OEM height setting screws foul the toolpost locking nut handle. Currently, if you need to swap toolposts you will have to first remove the quick-change tool holder from the post. There is enough nut handle swing to allow the quick change toolpost to be unclamped and rotated to fine set the tool angle without removing the toolholder. It also seems the mating surfaces may be slightly out of square, as if you rotate the toolpost 90° or 180°, the nut swing may be insufficient to re-clamp it without removing the toolholder to do so. Add a M10 washer under the locking nut if the handle ends up pointing in an undesirable direction! A thin M10 washer is kept with the toolpost collar for this purpose, and will shift the handle position by about a third of a turn. <br />
<br />
''ToDo: Make a taller nut of a similar pattern, to clear the height setting screws.''<br />
<br />
===Four Way Toolpost===<br />
The OEM four way toolpost is significantly more rigid than the quick change toolpost + holders because it has fewer and thicker parts and less overhang. Therefore the four way toolpost should be used when using carbide tooling. It requires shimming under the tool to set the tip height to the spindle center height - see below. The tool shanks are mostly significantly less than 15 mm wide, so need to be centered under its clamping screws, tempting as it is push the shank in for full side contact with the toolpost. If possible clamp the shank with all three screws not just two.<br />
<br />
==== Shimming ====<br />
We typically only mount up to two tools, and want maximum rigidity, so use 50 mm x 15 mm shims, (the full seat area), preferably with deburred edges and radiused corners so they aren't a hazard to the operator.<br />
<br />
We have pre-cut and marked shims of the following thicknesses: <br />
* 1x 3.23 mm, 2.42 mm, 1.56 mm, 0.32 mm, and 0.25 mm<br />
* 2x 1.00 mm, 0.77 mm, 0.12 mm, 0.11 mm, 0.10 mm and 0.05 mm<br />
* 4x 0.53 mm<br />
<br />
Our shims are mostly found materials (hence the awkward thicknesses) and are mostly a mixture of aluminium and steel, with a couple of GRP ones. The toolpost seat '''<u>must be absolutely clean</u>''' to avoid embedding debris in the aluminium or GRP shims, to get a consistent height and avoid tilting the tool - wipe it every time you change a tool! Put the thin shims at the bottom of the stack to avoid the tool shank edges creasing them. Shims are kept in a little yellow plastic box with a clear lid, near the carbide tools case.<br />
<br />
I made a tool height setting gauge (T shaped black acrylic with steps in its sides) which can be used to check the tool tip height matches the spindle center height using either the flat of the ways or the saddle as a reference. The tool tip should just fit under the lip of the appropriate step, with the T arms across the ways flats or on the saddle. It is kept in the box with the carbide insert tools.<br />
<br />
''ToDo:'' <br />
<br />
* ''Cut more shims neatly, mark them with their thickness.''<br />
* <s>''Do test cuts and start noting shim stack-ups for various tools.''</s><br />
* ''Organise shim storage!''<br />
<br />
=== HSS Tools ===<br />
[[File:Tool Bit Geometry.jpeg|thumb|Single point cutting tool geometry]]<br />
Our HSS tools are made from 8 mm square bar stock, hand-ground to tip profile in-house. See LittleMachineShop's [https://littlemachineshop.com/images/gallery/instructions/grindingtoolbits.pdf Grinding Tool Bits] notes. <br />
<br />
I've installed our usual HSS LH turning and parting off tools in two of the quick change holders and set the heights correctly. There are a couple of other HSS tools or tool blanks knocking about. Taking heavy cuts turning steel (even with good cutting oil) blunts HSS tools fairly quickly, which are time-consuming to re-sharpen nicely without a dedicated tool & cutter grinder with appropriate jigs. Its worth noting that the usual 'speeds & feeds' tables are commonly based on surface speeds expected to give a half hour (active cutting) tool life before resharpening.<br />
<br />
I touched up the LH turning tool by lapping on wet & dry (silicon carbide) paper on glass (Aka: [https://en.wikipedia.org/wiki/Scary_sharp 'Scary Sharp']) working upwards through the grits 200, 400, 600 and finally 1000, initially 'bluing' the surfaces to be lapped with a marker pen to see which areas needed taking down more. The end of the tool was significantly uneven so I touched that up freehand on the bench grinder to flatten it when it became apparent that 200 grit lapping wasn't cutting where it needed to. There was an existing micro-bevel on the leading side, which I kept. Finally I 'dubbed' the leading corner vertical edge on the 1000 grit to give it a very slight nose radius. A test cut on brass gave a very nice finish when turning.<br />
<br />
''Ian B has purchased some spare 8mm HSS tool blanks - talk to a lathe trainer if your proposed lathe work needs custom ground HSS tooling.'''<br />
<br />
=== Brazed Tungsten Carbide Tools ===<br />
Somewhat of a half-way house between hand ground HSS tooling and insert tooling with the disadvantages of both and some more besides - e.g. they are much harder to sharpen. So why do we bother? Some tool geometries would be awkward and tedious to hand grind, and Chinese import brazed carbide tooling is about half the price of similar HSS tooling, and far more readily available. Also, for space constrained tooling like boring bars, if you want carbide, for insert tooling, the size of the insert and its clamping seriously limits the minimum hole diameter you can work in. I have purchased a set of 3/8" shank brazed carbide tipped boring bars, but we currently cant sharpen them, due to lack of a diamond grinding wheel. <br />
<br />
=== Tungsten Carbide Insert Tools===<br />
Decoding ISO insert tooling part numbers: https://www.cutwel.co.uk/blog/learn-the-turning-tool-iso-code-system<br />
[[File:Carbide set.jpg|800px|thumb|left|Our set of Tungsten carbide insert lathe tools (before the new inserts were fitted)]]<br />
<br />
{| class=wikitable<br />
|+ Tools, left to right, (+ last across top):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| SSKCR0610H06 || 75° through boring || SCMT06204 || Long || 6 || 6.34 || ''4.33''<br />
|-<br />
| SSSCR0610H06 || 45° deep facing, internal chamfering || SCMT06204 || Long || 6 || 6.13 || ''4.58''<br />
|-<br />
| SWUCR0610H05 || 93° boring, deep facing || WCMT050308 || Long || 6 || 6.22 || ''4.48''<br />
|-<br />
| SWGCR0810E05 || 90° RH turning & facing || WCMT050308 || Short || 8 || 8.25 || '''2.45'''<br />
|-<br />
| SSSCR0610E06 || 45° turning, chamfering || SCMT06204 || Short || 8 || 8.75 || ''1.93''<br />
|-<br />
| SSBCR0610E06 || 75° RH turning, chamfering || SCMT06204 || Short || 8 || 8.72 || ''1.98''<br />
|-<br />
| LW0810R-04 || 60° external threading || JCL15-120 || Short || 8 || 7.44 * || ''3.28''<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || 8.23 || ''2.5 ?''<br />
|-<br />
| LN0813R-04 || 60° internal threading || JCL15-120 || Long || 7.95 || 7.44 * || ''3.28''<br />
|}<br />
<br />
{| class=wikitable<br />
|+ More Tools, (loose in tin):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || ~8.5 (not in use) ||<br />
|-<br />
| [https://www.glanze.co.uk/product/glanze-12-mm-60-degree-metric-internal-threading-tool/ Glanse SIR0012K11] || 60° internal threading bar || 11IRA60 || Long || 12 dia || ??? || ???<br />
|}<br />
''Shim stack heights in bold are tested, in italic are only calculated.'' ''Tip heights marked * are with new JCL15-120I inserts. The single remaining plain JCL15-120 insert has a slightly higher tip height.''<br />
<br />
Carbide tooling typically requires two to three times more speed than HSS and at least a couple of 'thou' depth of cut for best results.<br />
<br />
Chatter can rapidly kill carbide tooling by chipping the cutting edge. To improve rigidity and reduce the risk of chatter, the cross-slide and compound gib screws need to be well adjusted so there is minimal play in the slides, tool stick-out should be minimised, the four way toolpost should be kept over the cross-slide, and the work should be kept close to the chuck (or otherwise supported by tailstock or steady rest) to avoid excessive deflection.<br />
<br />
Thermal shock is almost instant death to carbide, and when dry cutting the insert tip can run very hot, so do not add extra cutting fluid manually during the cut. Pre-apply what you need, evenly, before starting the cut.<br />
<br />
Parting off or facing to center is high risk - if the tool tip is even slightly below center or if tool or work deflection takes it below center, the work will tend to climb over the tool tip as the cut approaches center, breaking the insert. To avoid this, the tool should be shimmed slightly above center, sufficient to allow for work and tool deflection, and unless very close to the chuck, a steady should be used. Its often preferable to part to a couple of mm dia. remaining then stop and saw through the remainder, then clean up by facing. Parting off hollow parts is much lower risk.<br />
<br />
Further investigation of the Tungsten carbide insert tool height situation is not encouraging - the so-called 'set' in question does not have a consistent tip height ''(see above table)''! In a real set, the insert seats *should* be machined allowing for the insert thickness to bring all the cutting edges to the same height with respect to the shank underside. However if you place them tip to tip on a table its easy to see there is considerable height variation, so they need to be individually shimmed (or at best, one machined shim will only be right for two or three tools). At this time we don't have dedicated shim stacks for each tool.<br />
<br />
A 2.42 mm thick shim brings the SWGCR0810E05 90° RH turning & facing tool almost exactly to center height, and good results were obtained turning 1" steel pipe. However facing 50mm steel bar stock to center found it to be slightly low, leaving a fractionally under 0.05 mm 'pip' so it needs another 0.03 mm to bring it fractionally above center. Fractionally too high is generally preferable to fractionally too low, due to tool deflection, so adding an 0.05 mm shim to the stack should produce optimum results.<br />
<br />
==== Inserts ====<br />
Ian B has purchased the spare inserts we needed in sets of five. He even was able to get the CK3 parting-off inserts which had been difficult to source!<br />
<br />
Inserts used in above tool set:<br />
* 3x SCMT06204 (square, indexable) https://www.rdgtools.co.uk/acatalog/SCMT-06-Carbide-Insert.html<br />
* 2x WCMT050308 (triangular, indexable) https://www.rdgtools.co.uk/acatalog/WCMT-05-T3-08-5XTIP-8813.html<br />
* 2x JCL15-120 (60 deg threading point) https://www.rdgtools.co.uk/acatalog/X5-JCL-15-120L-THREADING-TIPS-60-DEGREE--X5-TIP---23455.html<br />
* CK3 (parting off) https://www.rdgtools.co.uk/acatalog/CK3-CARBIDE-TIPS---PARTING--BOX-OF-5PCS--9437.html<br />
<br />
Inserts used in other tools:<br />
* 1x CK3 (as above) also missing from spare parting off tool<br />
* 1x 11IRA60 in Glanse threading bar + 1x spare<br />
<br />
=== Drills ===<br />
Various sizes of center drills are kept in a plastic bag next to the wooden accessories tray. There's also a small box of 2.5 mm center drills.<br />
<br />
We have a set of 11 TiN coated HSS drill bits from 1.5 to 8 mm, (in a cylindrical plastic index box) for tailstock drilling of brass, aluminium and non-abrasive plastics. To keep them sharp enough for the precision work we expect from the lathe, please don't use them for steel or reinforced plastics, and don't borrow them for non-lathe use. Metric and US [https://littlemachineshop.com/reference/numberdrillsize.php numbered]/[https://littlemachineshop.com/reference/letterdrillsize.php lettered] general use HSS drill bits are kept in two red metal index boxes next to the drill press.<br />
<br />
== Using the Lathe ==<br />
=== General ===<br />
Making dimensioned parts is primarily done by touching off the tool tip on a reference surface (with the lathe stopped, turning the chuck by hand), zeroing the handwheel dial, then manually counting turns and divisions. When backing off the tool its best to do so by exactly one whole turn so you don't forget the previous dial position. Stopping and measuring the work before taking the final cuts is essential if high accuracy is required. ''I've changed out the dial setscrews for flat tip ones with a tiny slug of solder under them so the dials are now friction fit on their shafts. i.e. if you hold the handle firmly taking up the backlash in the direction of cut, you can zero the dial just by grabbing and twisting it.''<br />
<br />
Carriage movement is less easy to measure as the handwheel is uncalibrated and advances an awkward bit over 19.2 mm per turn. Your options here when shoulders or other features must be exactly positioned are, in order of increasing accuracy: <br />
* Use measuring instruments, scribe the work at the desired length then work to the scribed line. Its often convenient to black the work with a permanent marker, then scribe with the tool tip, turning the chuck by hand.<br />
* for short distances, lock the carriage and use the compound, set parallel to the work<br />
* Set up a long travel dial indicator to measure carriage motion. <br />
N.B. with the leadscrew stopped, and the threading dial engaged, with its default 16 tooth gear, it will make one turn for every 24 mm of carriage movement (2 mm/div). This isn't accurate enough for positioning but is sufficient to check you aren't out by a whole mm or more.<br />
<br />
Do not allow any solvents to contact the chuck guard clear plastic as it will make the plastic brittle, or even craze it, and try to avoid melting it with the work light!<br />
<br />
===Speeds & Feeds===<br />
The surface speed of the tool relative to the work (or visa versa) is important, and best results will be achieved when it is in a tool type and material specific range. Because the surface speed is proportional to the diameter and the spindle RPM, it is usual to vary the spindle speed in inverse proportion to the diameter to get the surface speed in the desired range, and keep it there as the tool tip moves closer to the spindle axis. <br />
<br />
A cutting speed chart for HSS tooling, published by Model Engineer magazine can be found [https://www.model-engineer.co.uk/sites/7/documents/cutting%20speed%20chart.pdf [here<nowiki>]</nowiki>]. The second row is the target feed rate and the rest of the chart, apart from the diameter column is RPM.<br />
<br />
For carbide tooling cutting iron and steels, recommended speeds are generally three times higher than for HSS, but the CJ18A 2500 RPM max. spindle speed (in high gear) means you can only reach the optimum speed range for over 15 mm dia work. For small diameter work, HSS tooling may well be a better choice.<br />
<br />
An online metric speeds calculator is here: https://www.cgtk.co.uk/metalwork/calculators/cuttingspeeds <br />
<br />
How to do the maths to calculate speeds and feeds: https://www.cutwel.co.uk/blog/speeds-feeds-made-easy<br />
<br />
If you can hear the lathe 'sing' as it cuts, you are getting chatter, which invariably results in poor surface finish. Try decreasing (or possibly increasing) the spindle speed till the resonance stops. <br />
<br />
Once you have a wavy surface due to chatter, a light cut wont clean it up as the tool 'twangs' from peak to peak. You have to take a deep enough cut to get under it. For precision parts, its therefore desirable to take a trial finish cut while still 0.5 mm or so oversize, to give an opportunity to tweak the cut to get a good finish, check for taper, and that the part wont be undersize (on your test finish cut nominal diameter).<br />
<br />
=== Slide Locks ===<br />
* The carriage can be locked to the ways using the M5 hex screw through the top of the saddle to the left of the cross-slide. Double check the leadscrew is disengaged and the half-nuts open before locking it. Lock it when facing.<br />
* The cross slide can be locked by a M4 socket headed cap screw just in front of its middle gib screw. Locking the cross slide is helpful when turning very shallow conical features where the cross slide handle is in the way of the compound.<br />
* The compound slide can be locked by a M4 socket headed cap screw in line with the edge of the toolpost mount on the side with the gib adjustment screws. In normal use it should be kept backed off half a turn but it is desirable to tighten it for parting off operations to keep the resulting end faces flat.<br />
<br />
=== Compound ===<br />
The compound consists of a locking swivel and a top slide allowing cuts to be made at an angle to the axis e.g to produce bevelled or tapered features. There is a difference between US and UK usage, in the US a compound angle of 0° means the compound slide is parallel to the cross slide, but in the UK, 0° is parallel to the ways. The compound angle indicator on the CJ18A follows UK practice, 0° parallel to the ways, but it is not to be trusted, its out by a few degrees!<br />
<br />
One of the deficiencies of the CJ18A lathe is the difficulty of setting the compound angle. It is held and locked by two screws hidden under the top half of the compound slide, which must be wound back till its toolpost end is clear of the pivot point to access them. This may have to be repeated several times to snug them up enough to tap it to the desired angle, then finally tighten them. <br />
<br />
We generally keep the compound slide set approximately parallel to the ways so it can be used for short-distance longitudinal positioning without measuring. However it is unlikely to be closely parallel unless a test bar has been swept with a dial indicator on the slide, or test cuts made on a large OD workpiece and checked for taper.<br />
<br />
=== Chucks and Chuck Jaws ===<br />
==== Terminology ====<br />
* Inside jaws have steps on the outside to grip the ID of hollow work, but can also be used as outside jaws on small diameter parts (i.e. that fit through the spindle). <br />
* Outside jaws have steps on the inside to grip the OD of the work.<br />
* Universal chucks have a scroll plate with a spiral screw thread that moves all the jaws.<br />
* Independent chucks have individual adjusting screws for each jaw.<br />
<br />
==== The Chucks ====<br />
* The three jaw universal chuck can only grip near round or hexagonal work, which it centers, but its concentricity is not perfect so e.g. if you reverse the work and continue turning at the same diameter from the other end, you will see a line where the turned surfaces meet. It has separate sets of inside and outside jaws, and we normally keep the inside set installed to use as outside jaws for small diameter work.<br />
<br />
** Our jaws are individually numbered, stamped in the groove. They must be fitted in the correct sequence. The jaw slots are not clearly marked. Lowest runout for small dia. parts is achieved if you fit the jaws with #1 anticlockwise of the makers mark, then continue anticlockwise for #2 and #3.<br />
** A large strong rubber band is a great help getting all the jaws started on the scroll together - with slots #1 and #3 above the centerline and the scroll thread outer tip between #1 and #3, insert jaws #1 and #2 and put the rubber band round them to keep them in their slots. Insert jaw #3 and stretch the rubber band over it to hold it up into its slot. If the scroll was positioned correctly, all jaws should be at the same initial radius. The jaws can now be cranked in with the chuck key and they should all engage in step so they meet in the middle.<br />
:: ''Mini-lathe.com have the best instructions for [https://www.mini-lathe.com/mini_lathe/chucks/chucks.htm#Installing_Chuck_Jaws changing the jaws].'' <br />
<br />
* The four independent jaw chuck can grip most roundish or squarish work, which can either be carefully centered by the user, or deliberately gripped off-center. <br />
** Its jaws are reversible so can be swapped from inside to outside by simply cranking each jaw out and reinserting it the other way round, one at a time. DON'T move the jaws to different slots as they are likely to bind.<br />
** When setting up to face the sides of rectangular objects held crossways, it may be helpful to use both inside and outside jaw orientations, in symmetrical opposing pairs.<br />
** Its screws move their jaw 1/8" (3.125 mm) per turn<br />
<br />
* The jaws must '''never''' protrude from the chuck OD by more than one step, and for safety, its preferable they don't protrude at all, as they make the gap between the front of the bed and the chuck body an even more unforgiving meat grinder, and as the number of teeth engaged with the scroll or screw decreases, they loose strength, just when you need it the most to grip larger/heavier work. <br />
<br />
''Neither chuck is well suited to gripping tapered work safely. When seating work that doesn't quite fit through the chuck bore (which is larger than the 20mm spindle bore limit), be careful that it isn't seating on the chamfered edge of the chuck bore as it is far to easy to get the work slightly cocked so it doesn't run true.''<br />
<br />
==== Changing Chucks ====<br />
* When changing chucks, use the small grey plastic mat to protect the ways under the jaws in case you drop the chuck.<br />
* The spindle nose has two patterns of holes - the three hole pattern is for the three jaw chuck and the faceplate, and the four hole pattern is for the four jaw chuck. One hole is shared between the patterns, and is marked on the spindle nose.<br />
* To fit a chuck:<br />
** First check that the spindle nose and chuck back and recess are free of swarf, grit or other debris. Any foreign objects will tilt the chuck causing excessive runout and may mar the surfaces.<br />
** Remove the nuts and split lock washers from its studs, line its studs up with the hole pattern (preferably with the stud nearest anticlockwise to the makers mark through the marked spindle hole), fit and hold it in place with your right hand, and with your left, get the lock washer and nut on the top stud, and take up the slack.<br />
** One one nut is on, you no longer have to worry about dropping it, and can work round fitting the remaining washers and nuts, taking up the slack on each as you fit it. <br />
** Next, work round again getting them all finger tight, then tighten them gently, and finally work round fully tightening them. <br />
* Removal is the reverse of refitting. Put the washers and nuts back on the chuck's studs so they don't get lost.<br />
<br />
==== Gripping Threaded Work ====<br />
It is generally undesirable to chuck work gripped on a screw thread, as it is difficult to hold the work securely and get good concentricity while avoiding crushing the thread crests. However, if one must, one of the better ways of doing so is to wind a wire helix to fit the thread then clamp on the outside of the wire so it seats on the flanks of the thread. The wire should be mild steel or soft iron for steel parts and copper for aluminium and brass parts, single strand, round and of uniform diameter a little less than the thread pitch. It can be wound on the lathe, in reverse, by chucking a sacrificial mandrel of the same diameter and thread pitch, hooking the end of the wire round or under the jaw, against the direction of rotation, then holding the other end of the wire under tension with pliers and starting the lathe dead slow. Once wound and removed from the mandrel, the ends must be trimmed then it should be screwed on to the threaded work to provide a surface to chuck on.<br />
<br />
=== Faceplate Work ===<br />
Faceplate work is probably the most dangerous operation you can (or rather should) perform on a lathe. The working area is a large diameter spinning surface with protruding clamps to fixture the part that it is impractical to guard. Protruding clamps, studs, nuts etc. are very difficult to see at speed.<br />
<br />
'''Treat the faceplate with great respect and caution if you wish to continue to be able to count to ten on your fingers!''' <br />
<br />
The 65 mm cross-slide travel vs the 80 mm faceplate radius is a serious limitation that may require creative compound, toolpost and tool setups for larger parts, and doing full face cuts in two sections.<br />
<br />
''It is common practice to skim the faceplate to ensure it runs true. We have not (yet) done this, and wont till the spindle is in better bearings and the nose reground to minimise runout.''<br />
<br />
==== Clamping ====<br />
Open ended/sided clamps should be oriented so that cutting forces drive the work towards the clamping bolt/stud, not out from under the clamp. Minimize the protruding length of thread past the clamping nut, if necessary using sacrificial bolts or studs you can cut to length, or even using a long M8 stud for one of the faceplate mountings, so you can get a clamp nearer to the faceplate center. Double-check all clamps are secure, manually turn the faceplate to check the work and clamps clear the ways, top-slide and toolpost, and stand out of the 'line of fire' (a disc extending from the faceplate) when spinning up the work for the first time. <br />
<br />
If you need to machine close to a clamp, consider marking a safe limit circle on the faceplate and work with a marker pen to make it easier to see how close the cutting tool is to crash disaster. <br />
<br />
I strongly advise reading chapter two of Tubal Cain's book "Workholding in the Lathe" several times before your first faceplate setup, and if possible get another experienced lathe user to check your first few setups before spinning them up.<br />
<br />
==== Chuck Guard Removal ====<br />
The faceplate is too large diameter to fit under the chuck guard, but the guard has an interlock switch wqhich must be closed for the lathe to run. The guard is now fitted with wing nuts so it can be removed allowing the the interlock switch to close when using the faceplate. It *SHOULD* *ALWAYS* be refitted if a chuck is fitted, except when turning work too large to clear the guard. <br />
<br />
''The chuck guard is primarily there to make it very difficult to start the lathe without removing the chuck key and to reduce the area of large diameter spinning surface exposed. It may slow down the projectile if a chuck sheds a jaw but is unlikely to stop it. Also it serves to contain coolant spray spun off the chuck. As we don't use flood coolant this usually isn't an issue for us. As setting up for faceplate work doesn't use a chuck key, and the most hazardous zone is the face of the faceplate, with its spinning projecting clamps, with full access required for machining operations, which a guard would not cover, the consensus is that removing the guard is an acceptable risk.''<br />
<br />
=== Turning and Facing ===<br />
We are getting good results in aluminium, brass, and even steel using HSS cutting tools in quick-change tool holders, and the ~ 94 um/turn power feed. Unfortunately due to lack of rigidity in both the machine and smaller diameter parts, if you don't want the outer end to be over diameter, a light final cut and multiple 'spring' passes will probably be required.<br />
<br />
For aluminium, a sharp HSS tool and 0.5 mm (20 div) depth of cut gives good results with power feed for rapid stock removal. Its also easy maths as each cut takes ~ 1 mm off the diameter. Finish cuts should be much finer, 0.1 mm (4 div) is 'in the ballpark'.<br />
<br />
For steel, using carbide insert tooling, a 0.25 mm (10 div) depth of cut is more appropriate, and with pre-applied cutting oil, gives reasonable results with power feed if you use enough speed. The maths is not quite so easy as you are only taking 0.5 mm off the diameter per pass. Again, use finer finish cuts but try to plan your cuts so the final cut is still cutting, not smearing the surface!<br />
<br />
When facing or parting off, some skill is required to turn the cross-slide handwheel steadily to get a decent finish and to avoid shock-loading the tool tip. Increasing the spindle speed in one or more steps to keep up with the reducing diameter is advisable, but avoid speeds that cause resonances (resulting in chatter). When parting off, small through-hole parts may be caught on a thin rod chucked in the tailstock, and pre-positioned inside the work with its tip right up to the parting off position.<br />
<br />
==== Using the Steady Rests ====<br />
For the fixed steady rest, see Blondihacks' Lathe Skills #26 - How To Use a Steady Rest! [[#Youtube_Playlists_&_Videos|{below}]]<br />
<br />
Ours doesn't have ball bearing fingers, so a smooth surface on the work and adequate lubrication are essential. The thumbscrews can only tighten the fingers, so for small adjustments outwards you need to either slack off the clamping nuts or ease them slightly and use a drift against the back of the finger's slot. Once set, check the chuck still turns freely.<br />
<br />
The traveling steady rest needs to run on a machined surface, so at least for the first pass, must follow the tool, so its difficult to avoid using more compound slide overhang than is desirable. An initial surface should be cut next to the chuck or tailstock center before fitting the steady rest.<br />
<br />
Both are a PITA to fit - the fixed one has to have its clamping post inserted up through the bed, and the supplied spanner is useless near the headstock, and the travelling one's mounting holes on the saddle almost invariably need swarf picked out of them.<br />
<br />
==== Turning Between Centers ====<br />
<s>Using a MT3 to MT2 reducing sleeve, the MT2 dead center can be fitted in the spindle.</s> ''Currently the MT3 spindle taper is compromised.'' Alternatively, a soft center can be turned immediately before use in the three jaw chuck, but that must have its 60° point re-cut to concentric if the chuck is disturbed, and needs to be either large enough to bear on the chuck body, or must have a lip to bear on the end face of the jaws to take the axial thrust. Recutting the center is a PITA, as the compound angle must be set to 30° anticlockwise, then reset to a true 0° afterwards. Maybe a right-hand 30° end angle zero rake form tool is the answer, or use the carbide insert tool SSKCR0610H06 as a form tool with the toolpost rotated 15° anticlockwise.<br />
<br />
With the MT2 live center in the tailstock quill, this gives us a center either end of the work to hold it.<br />
<br />
We also need a drive dog similar to [https://littlemachineshop.com/products/product_view.php?ProductID=4473&category=1 this], and the corresponding drive post to bolt to the spindle nose. I have some 25mm bore thick wall iron pipe, which should do nicely. Lengths of the dog's straight tail and of the post TBD after I check how much the center protrudes. N.B. its recommended to tie the tail to the post to keep them in contact so they don't slam. ''Currently we will need to drive from the chuck jaws. Possibly use the exterior jaws with a short soft center gripped on the inside end and drive from the highest step.''<br />
<br />
=== Drilling ===<br />
Always start with a center drill so deflection of longer bits doesn't start the hole off-center. For larger bits (> 5 mm), first drill to the web size, then to final diameter. For a precision hole, drill slightly undersize and ream to final diameter. ''Supply your own reamers!''<br />
<br />
Caution: See note about the quill anti-rotation pin in section [[#Tailstock Quill|Tailstock Quill]] above.<br />
<br />
=== Boring ===<br />
Caution: As the spindle doesn't extend right through the headstock housing, if boring in a through hole, chips tend to fall out the back and tumble in the spindle bore till they fall into the change gears. To avoid this, one should plug the spindle bore with a wad of paper towel or rag and when cleaning up afterwards, use a rod to push it through towards the tailstock, with the chuck jaws (if fitted) wound clear of the spindle bore.<br />
<br />
A swivel bladed hole deburring tool (pale blue handle) can be found in the main room on the windowsill behind the drill press.<br />
<br />
A couple of boring jobs have been bodged with an awkwardly angled turning tool and achieving acceptable effective rake with enough clearance to reach deep enough into the hole has been problematic. I reviewed the tools we had and found none suitable for starting out in a 13mm bore, the max diameter we can (easily) drill. I therefore decided to buy a set of boring bars and make a holder for them. I had difficulty finding anything affordable under 10mm shank - the best low cost option was a [https://www.amazon.co.uk/dp/B07P5LGVBX set of nine 3/8" (9.525 mm) shank brazed carbide tipped boring bars], which would be close to the max capacity of the quick change boring bar holder - if we had one! Unfortunately this holder for our specific toolpost is difficult to find except in a toolpost bundle. Another annoyance is the variable tip height of the set, varying from 1.8 mm to 2.8 mm above the center of the shank.<br />
<br />
I therefore decided to make a boring bar holder of the [https://littlemachineshop.com/products/product_view.php?ProductID=1700 Littlemachineshop.com (USA) style] for use in the four way toolpost, as the additional rigidity will certainly help. Starting with a slightly over 50 mm length of 16 mm aluminium square bar and using the four jaw chuck , both ends were faced and an attempt was made to find its center and center drill it. It was then drilled out to ~9.8 mm after much drama due to blunt drills and drills that cut ~1mm oversize. Too big, but beggars cant be choosers as we didn't have a boring bar holder or a 3/8" reamer. Unfortunately the final hole ended up significantly off center. It was then chucked crossways and ~1 mm skimmed off its thickest side to gain clearance to allow it to be shimmed to height, then one side was slit lengthwise manually with a hacksaw.<br />
<br />
It was fitted to the for way toolpost and loaded with a booring bar, which clamped firmly. A 0.86 mm shim stack brought the tip of the largest boring bar almost spot on center height, with the difference easily accommodated by twisting the tool slightly. The three jaw chuck was then remounted, and a piece of iron pipe chucked for a test. It cuts well and leaves a decent surface finish.<br />
<br />
''The boring bar setup is a work in progress - talk to me before attempting to use them if you have a project that would benefit from boring..''<br />
<br />
ToDo: get something that can sharpen tools tipped with this grade of carbide - it needs some sort of diamond (or possibly CBN) wheel as green grit silicon carbide does little more than polish it. ''N.B. diamond wheels are rapidly eroded by grinding steel, so the supporting steel seat must be undercut with a regular grinding wheel before the diamond wheel can contact it.'' <br />
<br />
We'll also need 50 mm square sheet shims to fit under the toolpost to gain clearance in the toolpost above the tool or toolholder. A 2.4 mm shim would give us about the same above and below spindle center height, and we probably need a small selection of thinner ones.<br />
<br />
=== Thread Cutting ===<br />
The objective is to cut a thread that complies with the ISO metric thread profile. Our lathe is not currently equipped to cut non-metric threads, (with the exception of BA which have pitches based on metric threads of that era).<br />
<br />
[[File:ISO and UTS Thread Dimensions.svg|frame|center|Metric Thread Profile - from the geometry, H is ~86.6% of P]]<br />
<br />
Metric thread data - See 'Preferred Sizes' at: https://en.wikipedia.org/wiki/ISO_metric_screw_thread<br />
<br />
See "Mini Lathe User’s Guide" section '''Threading''' for general techniques *ONLY*, and above for change gears and threading dial setup.<br />
<br />
Amadeal specify the max. thread pitch as 2.5 mm. Any thread pitch greater than 1.5 nn requires the change gears to gear up. When gearing up it is desirable to distribute the ratio as evenly as possible over the two pairs of gears in the geartrain to avoid excessive tooth loading.<br />
<br />
==== External Threading ====<br />
Initially turn work to required Major Diameter, set up change gears and threading tool, touch off on the work, zero the top and cross slide dials, and do a 'scratch' pass to check the pitch. Back off the tool, return the carriage, and re-engage the half nuts on a valid dial line clear of the end of the thread then immediately stop the lathe, and hand turn the chuck till the tool tip is (hopefully) over the scratch to check the thread pickup. If all is good, return the carriage again, restart the lathe and start cutting your thread. <br />
<br />
Methods of doing so vary depending on the size of the thread and toughness of the metal, but straight-in plunge cutting is generally to be avoided as has the highest cutting forces, and does not reliably keep the carriage (and top-slide if set parallel to the work) loaded to avoid pitch errors due to backlash. <br />
<br />
If leaving the half-nuts engaged and reversing the lathe to return to the start of the thread for the next pass, its absolutely essential to back the tool out of the thread for the return pass as it will not follow the path of the cutting pass due to backlash in the geartrain, leadscrew mounts and half-nuts.<br />
<br />
==== Internal Threading ====<br />
''<nothing here yet>''<br />
<br />
== Cutting fluids ==<br />
=== Why bother? ===<br />
[https://youtu.be/mRuSYQ5Npek Watch this video] and contemplate what's actually happening to that thin ribbon of metal being removed. Most of the lathe's motor power is being turned into heat by internal friction in the chip being removed in the zone around the cutting edge, and surface friction at, and immediately behind the cutting edge, near-instantly heating the chip by up to several hundred degrees. Reducing the surface friction using a suitable cutting oil reduces the strain on the machine as a whole, and reduces workpiece and tool heating (and thus expansion) with consequent improvements in maximum usable feed and depth of cut, surface finish and accuracy. It also drastically increases the life of the cutting edge.<br />
<br />
=== Practicalities === <br />
We don't have a coolant system for the lathe and *really* don't want the maintenance hassles of using soluble cutting oil/coolant as if used infrequently its a PITA to keep recirculated high water content cutting fluids from going rancid and stinky, and they can also rust the ways, so even a total loss gravity feed system is problematic. Therefore if dry machining doesn't give a good enough finish, we tend to use oil applied topically, by hand to the work. <br />
<br />
* Hard brass is typically free-turning without oil, however some light oil for the final cut can improve surface finish, but with the disadvantage that it will increase loose chip buildup on the tool as hard brass typically forms short spalls or splinters rather than curly chips.<br />
<br />
* Many Aluminium alloys tend to be gummy, and Paraffin or other mineral spirits mixed with a little oil can help prevent the aluminum welding to the tool edge. WD40 will do at a pinch, but its messy to apply from a spray can.<br />
<br />
* Steel really needs *GOOD* cutting oil. Lard oil is the traditional choice for steel. If there are any objections to lard oil, we should bite the bullet and get some commercial dark high Sulphur cutting oil, but beware, many such oils use an additive package that includes lard oil.<br />
* Cast iron (except ductile) should be cut dry, as the carbon micro-inclusions self-lubricate it, and the carbide in the dust (primarily Cementite) are very abrasive, so tend to form a grinding compound if mixed with oil. <br />
<br />
I've sorted out an oil pot lid with a 1/2" brass collar soldered in to give a nice smooth sided hole, for ease of use and to minimize the risk of spills when using a brush to apply cutting oils, and got some dirt-cheap brushes. It fits Shippam's paste (and similar own-brand spread) jars and I've found several jars and ordinary lids to seal them for storage. Unfortunately it isn't the easiest to get this type of jars' lids back on square so they seal properly, and if you over-tighten them and there's a temperature change, they can be a total <expletive> to reopen. Using the rubberised handles of a large pair of pliers to grip the jar lid just above its rim is the best option, and avoids damaging the lids.<br />
<br />
''N.B. For the smaller brushes, the glue holding the bristles in is attacked by paraffin. To prevent loss of bristles, crimp the aluminium ferrule of each new brush of this type before use.''<br />
<br />
We have, in labelled jars:<br />
<br />
* Sulphurised Lard oil thinned with paraffin. Best choice for heavy cuts and threading in steel but stinky.<br />
* Lard oil thinned with paraffin. Good for steel and acceptable for softer copper alloys<br />
* Paraffin with a trace of light oil. Good for aluminium, and can help prevent squealing chatter on finish cuts in brass.<br />
<br />
I've also got some paraffin wax (in the form of a stubby candle), which can be applied lightly (under power) to brass and aluminium stock especially on the finish pass. It makes less mess than oil but unfortunately tends to build up on the tool tip, making it difficult to 'work by eye' without frequent pauses to clean the tool tip.<br />
<br />
We've also got a tin of [https://www.rocol.com/products/rtd-compound Rocol RTD cutting compound], which is a thick paste. Its highly recommended for drilling and tapping steel (in the drill press or by hand), but as a paste, is less useful for general lathe work unless thinned to a fluid consistency, e.g. with paraffin or white spirits. OTOH its certainly worth trying for high speed facing steel as it is less likely to get flung off.<br />
<br />
== Cleaning and Maintenance ==<br />
Swarf is a significant cut hazard to the operator, especially stringy swarf from cutting steel. Never touch it bare-handed - always use a tool e.g. a brush, or a hook, or needle nose pliers for grabbing long swarf.<br />
<br />
* After use, brush all swarf off the toolholder, compound and cross slide etc. ways and leadscrew. Ian B has blocked off the opening at the headstock end of the rear splashguard (to try to keep swarf out of the motor), so one must sweep the swarf towards the open tailstock end and catch it in a dustpan or similar. Preferably, also thoroughly clean out the chip tray under the lathe, but at least sweep out visible swarf.<br />
* Wipe up any cutting fluid residue and re-lubricate affected sliding surfaces with way oil.<br />
* Do not solvent clean the chuck guard, as it will make the plastic brittle, or even craze it. Water with a little detergent is permissible for cleaning it, with the guard totally removed from the lathe.<br />
<br />
Before engaging the half-nuts for power feed/threading, check the leadscrew is clean! ''Best cleaned under power, with a toothbrush.'' <br />
<br />
'''Caution:''' The traverse gears behind the carriage handwheel are in an open-backed housing and tend to become packed with swarf! Swarf buildup here will result in jerky carriage movement. Clean out as much as you can with a toothbrush ...<br />
<br />
===Lack of lubrication and/or swarf or dirt build-up can be disastrous===<br />
* If using the change gears/power feed, lack of lubrication of the B-C stub shaft center pin or either leadscrew end bearing can result in seizure and immediate destruction of one or more gears in the gear train or worse. <br />
* Small pieces of swarf can get between the saddle and ways, or into the slides degrading accuracy, possibly permanently if hard swarf scores them, or jamming them. The carriage handwheel gears behind the apron are notorious for accumulating swarf, and swarf buildup on the leadscrew can prevent the half-nuts engaging properly, resulting in scrapped work, and possibly stripped half-nuts. <br />
* Metal swarf can get into the motor (''though Ian B has modified the rear chip catcher to reduce the risk)'' or into the control box via the leadscrew, and short-circuit stuff. At best it will blow the fuse and need a strip-down to clean it out, at worst it may require a replacement [https://www.amadeal.co.uk/acatalog/Speed-Control-Circuit-Board--12amp-AMA_SP_CJ18_SCB12.html#SID=12 speed controller] ''(currently £96)'' and/or [https://www.amadeal.co.uk/acatalog/550W-motor-for-CJ18A-Mini-Lathe-467.html#SID=240 motor] ''(currently £105)'' and possibly other electrical parts. We should probably fit a [https://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C3-Mini-Lathe-Spares/C3-256-Leadscrew-Grommet-Dustproof-Cover C3-256 Leadscrew Grommet] to keep swarf out of the control box, as it tends to drop onto the 'Filter' board which is mounted horizontally, below the leadscrew.<br />
* Grit from grinding, sanding etc. forms a grinding paste with the way oil, and will rapidly wear out the ways, saddle and slides. Keep grit off at all costs e.g. by covering the ways and slides during grinding/sanding operations, and if there's any chance grit has gotten where it shouldn't, clean and re-lubricate *BEFORE* moving the carriage or slides, then move the carriage and slides, wipe down where they were with a clean paper towel and check there's no remaining traces of dirt other than clean way oil on the paper towel. If it doesn't come clean when you re-lubricate and move it again, a full strip down may be required to solvent clean and relubricate the precision sliding surfaces.<br />
* Although a metalworking lathe *can* be used to turn hardwood, wood dust and small chips are extremely pernicious, as they get everywhere, even clinging to clean surfaces, are abrasive due to their silica content, and are hygroscopic, promoting rust. An even more thorough clean-up than after using abrasives is needed, immediately afterwards. Oily wood dust and fine wood chips in significant quantities are a fire hazard, even in the trash bin.<br />
<br />
===Lubrication===<br />
See section: "Lubrication" in LittleMachineShop.com "Mini Lathe User’s Guide" [[Ian_M's_Lathe_Notes#Manuals|(below)]]. As we usually only open two nights a week, in the table on page 16, Daily lubrication becomes Weekly and Weekly becomes Monthly.<br />
<br />
===General Maintenance===<br />
* The grubscrews holding the cross-slide and compound slide dials tend to loosen due to vibration and use of the dials. Keep them snugged up, but not so tight the dials cant be set without an Allen key.<br />
<br />
* The screws holding the cross-slide nut tend to work loose due to vibration. Crank the handle to and fro through the backlash and visually check there is no movement of the screw heads in their holes. If there is, see the [[#Excessive_cross-slide_backlash|notes below]].<br />
<br />
===Removing the Carriage===<br />
Its possible to remove the carriage from the bed for cleaning etc. without dismantling it. The only stop to its motion is the righthand leadscrew bearing.<br />
<br />
Start by removing the tailstock. Crank the carriage to the tailstock end then remove the leadscrew bearing (two screws and a nyloc nut on the leadscrew end). With the half-nuts open, hold the leadscrew centered in them and crank the carriage off the end of its rack, then slide it off the end of the bed.<br />
<br />
Refitting is the reverse of removal, except (if its gibs are correctly adjusted) the carriage will be very tight on the end of the bed ways so may be difficult to work onto the ways without a stack of blocks of wood or similar to support it at exactly the right height. The righthand leadscrew bearing must be refitted with the carriage as close as possible to it and the half-nuts firmly closed to support the leadscrew at the correct height to hold it in alignment while the screws are being tightened. The nyloc nut controls leadscrew end-play. Fully tighten it then back it off slightly till the leadscrew turns freely with its change gear removed.<br />
<br />
If the Apron has been off, refit it with the screws no more than lightly finger tight and only finally tighten them after checking lead screw engagement at both ends of the carriage travel and that the rack and pinion operates smoothly over the full travel.<br />
<br />
== Issues and Annoyances ==<br />
As of September 2023 - mostly resolved, apart from the spindle bearings and runout, the lathe is in better condition than it has been for a number of years.<br />
<br />
===Four Jaw Chuck has two jaws too tight===<br />
Fixed 27/10/2023: Two of the chuck jaws were tight in their slots, making precise adjustment difficult due to lack of 'feel'. Moving the jaws round the slots showed the problem mostly followed the jaw not the slot. The grooves in the opposite sides of the affected jaws that run in the chuck slots were slightly out of true, and the rails either side of the slots were slightly too thick towards the center. Due to the difficulty of seeing the high spots, after cleaning up and deburring the jaws didn't do enough to ease them, I decided to grind the top of the rails where they were binding. Several repetitions of spotting with Engineer's blue, grinding, then diamond filing the high spots has eased them enough. I cleaned everything, greased the jaw slides and screws, and refitted the studs so the chuck is now fit for service.<br />
<br />
''N.B. Don't move the jaws to a different slot - the formerly tight jaws *must* stay in the slots furthest from the makers mark.''<br />
<br />
===Excessive Runout===<br />
Mostly fixed 24/10/2022: I ground the chuck seating surface of the spindle nose (outside lip) to under half a thou runout. This also cleaned up several burrs. It would be possible to do better, but that would need good spindle bearings, and a more rigid toolpost grinder mount.<br />
<br />
Our spindle nose was damaged years ago by a person with little mechanical aptitude (who shall remain nameless) beating it up with a hammer mushrooming the spindle nose. We are getting several thousandths runout at the end of the MT3 bore, a MT3 to MT2 reducer sleeve in it runs visibly out of true, as does the spindle nose flange. When you put a chuck on it, the runout is magnified by the distance from the spindle nose. Ideally we would replace the spindle when we change the bearings but its £52 [https://www.amadeal.co.uk/acatalog/4-Spindle-Upgrade-Real-Bull-Mini-lathe-CJ18-series-AMA_SP_CJ18_003RB.html#SID=9 from Amadeal] and money is tight. It may well require more work after the bearing upgrade. Once good bearings are in, if we can borrow a decent MT3 arbour as a reference, we should consider skimming the bore.<br />
<br />
===Spindle bearings===<br />
* The spindle bearings appear to be close to worn out. They are notably noisy when running, and there appears to be more slop in the spindle than is desirable. There is notable resonance around 600 RPM, and surface finish of end faces is often poor. We have some ideas for possible replacement/upgrade, but it requires a major teardown.<br />
<br />
: The original bearings are allegedly 6206-2RS or 6206-ZZ deep groove ball bearings - 2RS codes rubber seals both sides and ZZ codes metal shields. Although the deep groove gives reasonable ability to withstand axial loads, the bearing balls point contact means they are vulnerable to [https://en.wikipedia.org/wiki/Brinelling brinelling] due to shock loading. The jammed on three jaw chuck didn't help this, as before we skimmed the spindle nose lip, it had to be driven off using a bar through the spindle bore, shock loading the bearings every time. Also even a minor 'crash' could have brinelled them due to eccentric shock loading, and the lathe has previously been crashed badly enough to need drive gear replacement. There are also issues with the 'approved' method of spindle and bearing removal from the headstock brinelling them, even if you don't abuse the spindle nose with a hammer!<br />
<br />
: A possible replacement is 30206 tapered roller bearings. The new bearings are slightly thicker so the plastic spindle spacer (15) needs to be machined to length to get the 45 tooth spur gear that drives the change gears laterally aligned with the tumbler gears. If a temporary replacement (3D printed?) is fitted, the lathe can be run (without power feed capability) so this can be done on the lathe after fitting the new bearings. As tapered roller bearings have line contact, they are significantly more resistant to brinelling.<br />
<br />
: ''See [[Talk:Ian_M%27s_Lathe_Notes]] for notes, links etc. for this upgrade.''<br />
<br />
===Motor stuttering===<br />
* Fixed 21/09/2023: The motor was running very erratically and it was very difficult to set a speed. Several loose connections were found in the control box, mostly loose female spades to the motor controller board, but also a dry jointed braking resistor on the 'Filter' board, and an inhibit wire completely off its terminal on the forward/reverse switch, making intermittent contact. After tightening and/or remaking all affected connections, it was much improved but still not right below 300 RPM. The remaining issues were due to poor wiper contact in the speed control pot, and stripping it, cleaning the track and contact ring and re-tensioning the contacts resulted in the motor now running smoothly over the full speed range. The speed is slow to settle, and while part of that is probably the lag in the digital tach, I suspect that the KBIC motor speed controller isn't properly tuned as it was (allegedly) previously replaced.<br />
<br />
===Drive belt slipping===<br />
* Fixed 28/9/2022: During testing the motor after the above issue, it was noted that the chuck could be stalled, slipping the drive belt, with not much torque. The drive belt was determined to be loose and a bit worn, but still in acceptable condition. <br />
<br />
: Access for servicing the belt requires removing the control box ''(2 spades to ZVR switch disconnect the supply, speed sensor and motor simply unplug from the 'filter board')'', the motor cover, chuck guard switch assembly + wiring cover, the change gear 'A' (drive) shaft carrier assembly, and the tumbler gear assembly. See https://youtu.be/EkxlIz01BdA for disassembly/reassembly, though on our lathe, the speed encoder ring on the spindle prevents the belt cover from being fully removed without disturbing the spindle nuts. There is enough room to work with it loose, but still trapped by the encoder ring. Also, unlike the video, if the 'jack' screws under the headstock are correctly adjusted, and the studs aren't excessively bent, there is no need to make custom studs. <br />
<br />
: It turns out that our lathe was missing the M6 hex headed jack screws that press the motor down to resist the belt tension, and the motor had cocked out of position at a severe angle. I know Ian B had had considerable trouble adjusting it after the motor fault back in October 2022, and I believe it had been getting slowly worse ever since. The jack screws were probably mistaken for headstock fixing bolts during disassembly after the crash that resulted in the metal Hi/Lo gears being fitted, then lost. The penny washers on the studs had dished, so I turned them over and backed them up with smaller washers and switched to Nyloc nuts so they cant back off due to vibration. N.B. There is a packing washer on the motor side on one of the studs, presumably so the shaft is true to the ways. Adjusting the motor is awkward to say the least. One has to slack the stud nuts off a lot, pry under its rear end to lift it enough to be parallel to the ways, snug the stud nuts, check alignment, then set the jack screws and their lock nuts to hold it there, and finally tighten the stud nuts. <br />
<br />
: Tension: According to Sieg, it should be possible to twist the belt 90° mid span with a light finger grip. Other sources say 1/32" - 3/32" deflection mid span with light finger pressure.<br />
<br />
===Speed display blanking===<br />
* The speed display has been intermittent, blanking and flashing 8888 and 0 at certain speeds for as long as I have been using the lathe. Finally on 18/07/2022 it failed completely, with no display. I removed the display module and bench tested it - the pins are labelled 5V GND PL PE, PE is frame ground and PL is a TTL level pulse from the speed sensor - confirming that it was in good working order. My suspicions then turned to its power supply on the 'Filter' board. With both the sensor and display unplugged, the 5V rail was found to have a only a couple of volts, but the unreg DC was 17V and stable. Replacing the 78L05 5V regulator restored the 5V rail and normal operation.<br />
<br />
: ''I conclude its been failing for a while with high load current due to speeds with more lit segments causing it to drop out, resetting the speed display, causing it to blank, lowering the current enough for the regulator to recover, then the display MCU lamp tests (8888) then re-acquires the speed, repeating ad-nauseum till the speed is changed. I don't like the design as the high input voltage results in excessive dissipation.'' <br />
<br />
: ''ToDo: If it fails again, bench test display to measure its worst case current consumption, then fit an appropriate dropper resistor to reduce the 78L05 dissipation.''<br />
<br />
===Quill spinning when drilling===<br />
* The quill was tending to spin while drilling because its anti-rotation pin (a M5 dog tip setscrew) was sheered. I've removed the debris, aligned the scale with the top of the tailstock and fitted a longer M5 dog-tip setscrew to replace it, with a nut to lock it at the correct height. N.B. the pin isn't that 'meaty' so if using big drills in tough metals, to prevent shearing it, it should be backed out so the quill can be turned by hand and unwanted rotation controlled by being quick with the quill lock if it starts to spin, or even using a close fitting rod in one of the chuck key holes with plastic tube over it to protect the ways. <br />
: ''If the screw sheers again, the quill will need to be removed and the tailstock taken off the lathe so the sheered tip can be shaken out, and if the setscrew is difficult to remove it probably means the threads are mangled where it sheered. Try driving it right through with the quill out.''<br />
<br />
===Sloppy quick change toolpost locking mechanism===<br />
* Once the dovetail clamp screw was slackened, there was nothing preventing the dovetail twisting or cocking significantly, and friction with the toolholder made it tend to do so, making toolholder insertion and removal more difficult unless the clamping screw was backed off excessively. I added a compression spring around the clamp screw inside the toolpost to push the dovetail outwards so it mostly retains alignment when open, allowing toolholders to slide on or off cleanly with far less screw slackening.<br />
<br />
===Leadscrew rubbing===<br />
* The leadscrew shaft is rubbing on the insulating separator inside the control box. Unfortunately the corner of the relay on the Filter Control Board (#160) doesn't allow enough clearance. Although the friction isn't much of a problem at high reduction ratios, e.g. 16:1 power feed, it increases the stress on the change gear train, and may be problematic when threading at feeds above 1:1. ''Possibly pack out the control box mountings by a couple of mm.'' <br />
<br />
===High/Low lever backwards!===<br />
* The high-low drive gear selector behind the headstock is incorrectly labelled and differs from the manual: low gear (which we normally use) is with the lever towards the tailstock. ''I suspect that the gears in the headstock were refitted the wrong way round when it was upgraded to metal gears.''<br />
<br />
: ''ToDo: Get it reassembled the right way round during the spindle bearing upgrade!''<br />
<br />
===Carriage lock fouls top slide===<br />
* The T handscrew has been replaced with a M5 hex headed bolt, to permit access when the top slide is over it. An 1/4" drive 8mm socket is usually left on it, but needs to be removed when the full cross slide travel is needed. The small (4 jaw) chuck key is near enough 1/4" to use for it. If you need to (un)lock it while the compound is over it, you'll need an 8mm spanner. ''The [https://www.amadeal.co.uk/acatalog/Mini-Lathe-Carriage-Lock-463.html Amadeal lock screw] is in the spares tin as it was too high and fouled the compound slide.''<br />
<br />
===Tailstock locking lever loose===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock - See full image for key to screws]]<br />
* Diagnosed and fixed 10/1/2023 - In the base of the upper section of the tailstock, there are two dog tip set screws that engage with locating grooves in the counter-rotating shafts carrying the eccentric locking cams. They'd backed off, probably due to vibration. They need to be tightened till they bottom out in the groove, making sure they are '''in''' the groove, backed off half a turn so the shafts can turn easily, and locked in place. There's no facility to do so, so reassemble with weak threadlocker. Unfortunately to get to them you have to remove the tailstock base slide, which is held on by the pressure of four adjusting grub screws, which all need backing off, and one socket headed bolt from underneath so full tailstock realignment is required after reassembly, which even for a rough alignment is tedious.<br />
: <s>The tailstock locking lever is loose and can be pulled out on its axis. It works OK when fully pushed home but needs investigating. ''I tightened the grub screw as the lever was coming off its shaft, but the whole shaft pushes/pulls in and out. It works OK fully pushed in, but it seems something that is meant to retain it has failed inside the tailstock base.</s><br />
<br />
===Gear alignment issues===<br />
* Change gear alignment is poor. I've currently got a gapped washer (to clear the key) packing out the A shaft so the gears line up, but this reduces the key's engagement so is problematic due to the high loading if the gears are set up for coarser threads. <s>Also I need to turn down some penny washers to slightly less than the root diameter of the metal 20T pinions, as gear retaining washers.</s> ''The gear retaining washers for A gear and B-C stub shaft are now done, turned down to slightly under 16 mm dia. Spares in the change gear tin. ToDo: The D (leadscrew) washer requires a larger center hole, so make two more with that hole.'' <br />
<br />
===Saddle gibs loose===<br />
* Fixed 11/04/2023: I took the apron off for access (and to clean the carriage handwheel gears), and found the front sheer plate screws were completely loose. I've snugged them up some and set the opposing grub screws and got a lot of the slop out. I've re-checked the front ones, and taken up the slop in the rear ones - Unfortunately it wasn't possible to get carriage movement to have an even 'feel' over its whole travel, and its noticeably tighter near the tailstock. If light hand pressure on the side of the unlocked carriage can cause movement (with the half-nuts open), its time to readjust them again, though it should be possible to move the carriage with a firm push. <s>The saddle gibs (actually the sheer plates) were too loose, to the point that engaging a slightly stiff threading dial could cause it to self-feed, an obvious crash hazard if working near the chuck or a step in the work.</s><br />
<br />
''N.B. the lefthand front opposing grubscrew is short, (fully recessed) and unlike the others does *NOT* have a locking nut as it must clear the traverse pinion. A wrap of PTFE tape provides enough friction to keep it in place, though possibly a bit of nylon fishing line down its hole would be better.''<br />
<br />
===Excessive cross-slide backlash===<br />
* ''Fixed 21/11/2023.'' Originally, back in October 2023, The cross-slide screw had excessive backlash (nearly three turns), which increases the risk of loosing track of the cut depth when cutting steps, and during threading operations. If you ended up off by a turn too far in, a crash would be the most likely outcome.<br />
: The original excessive backlash was traced to loose cross-slide screw nut mountings. The nut has two socket headed cap screws pulling up, one either end, accessible from the top of the cross-slide, which control the tilt of the nut to take up backlash in the nut, and an opposing grub screw pressing down on the center of the nut to make it longitudinally rigid. Snugging up the grub screw reduced the backlash to 10 divisions or so, or 0.25 mm. A year later, the backlash had increased to one turn due to the cross-slide nut mounting screws working loose again.<br />
<br />
: 07/11/2023: I investigated further: It is difficult to get the cross-slide nut aligned correctly as it must be at the same height as the screw which is constrained by the bearing surfaces in the bracket. With the cross-slide almost at the front limit of its travel, I removed the screw and set the nut as level as possible and visually centered in the bore, then re-fitted the bracket and screw, then adjusted the tilt till it turned freely through the backlash. I then tilted it up at the front till some drag was felt to minimise the backlash and tightened the screws to lock it in place balancing them to maintain the same feel as I tightened them. The result was 7 divisions of backlash, acceptable but not great. During normal turning operations, the load on the nut is tension on the front screw and pressure on the grubscrew, so if it slackens again due to vibration from chatter, odds are it will be the rear screw that's loosened.<br />
<br />
: 16/11/2023 - 21/11/2023: The backlash had crept back up to 11 divisions (0.275 mm). We don't have any >14 mm brass stock (or even near that) so I tried making the shim washer out of aluminium. I was shooting for 0.24 mm but due to poor technique got 0.28 mm. No good - locked solid. I lapped it down and tried it till I got it down to 0.20 mm which gave about 3 divisions backlash - good enough, but the screw was too tight due to the shim washer not being bevelled at its outer edge resulting in it cupping in its seat. Filing a bevel round the OD and re-lapping it resulted in a 3 - 4 divisions of backlash. Its a little mushy due to the washer having been kinked removing it, so ideally a new (brass) washer should be made. <br />
<br />
* Further reduction of backlash: https://youtu.be/Wu_tI29JL2Y?t=163 <br />
: Brass tinned with Pb-free solder to form a white metal bearing surface should work at least as well as the bronze used in the video. The shim washer needs to be 10.2mm ID, with a full thickness bevel on a 14 mm OD. It isn't necessary to remove the lead screw from the cross slide, as the washer can be fitted in-situ with only the bracket removed.<br />
<br />
===3 Jaw chuck didn't mount properly===<br />
* Fixed 7/4/2023 by grinding the spindle nose lip. The three jaw chuck can now be installed and removed by hand with no hammering. A test bar in it now has only 2 thou runout (TIR) at the chuck.<br />
: <s>The three jaw chuck and the faceplate aren't seating properly on the spindle nose. Its too tight on the register diameter of the lip. This results in grossly excessive runout, and also makes this chuck and the faceplate a PITA to fit or remove.</s><br />
: ''The spindle nose had been abused with a hammer (before my time) which mushroomed it and may have brinelled its bearings. See '''Excessive Runout''' and '''Spindle bearings''' above.''<br />
<br />
== Manuals, Books and other resources ==<br />
=== Manuals ===<br />
The [https://wiki.richmondmakerlabs.uk/images/a/a3/Lathe_InductionNotes.pdf RML CJ18A Mini-Lathe Induction Notes]. Your mandatory Lathe Induction will cover most of this but its good to be able to refer back to it. Also see: [[File:Lathe Induction Bushing.pdf|Lathe Induction Bushing]] which you will make during your induction.<br />
<br />
Official [https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Amadeal CJ18A Manual], or paper copy (less complete) kept on shelf above lathe.<br />
<br />
The [https://www.chesterhobbystore.com/wp-content/uploads/2022/11/Conquest-Super-Lathe.pdf Conquest Super Lathe manual] is considerably better than the Amadeal manual and is for a near-identical machine.<br />
<br />
The [https://littlemachineshop.com/images/gallery/info/minilatheusersguide.pdf Mini Lathe User’s Guide] from LittleMachineShop.com is even more comprehensive, going into its usage in some detail, with a proper TOC, and covers both US and Metric versions of Realbull Mini-lathes. ''The only fly in the ointment is the threading section assumes a US lead screw so change gear selections and threading dial divisions will not be correct for our lathe.''<br />
<br />
[https://www.arceurotrade.co.uk/machineguides/C3-Mini-Lathe-Dismantling-and-Reassembly-Guide.pdf Sieg C3 Mini-lathe Dismantling and Reassembly Guide] "A picture story book to help you dismantle and reassemble your Sieg C3 Mini-Lathe" ''It is similar enough to ours to serve as a maintenance guide, except for the electronics, spindle drive and other headstock innards.<br />
<br />
The motor controller is a clone of a [https://acim.nidec.com/drives/kbelectronics/-/media/kbelectronics/documents/dc-drives/manuals/kbic_manual.ashx?la=en KBIC® SCR DC Motor Speed Control]<br />
<br />
=== Books ===<br />
'''Metal Turning on the Lathe''', by David A Clark, Crowood Metalworking Guides, ISBN-13: 978-1847975232 [https://www.amazon.co.uk/gp/product/B00E78RKIG Kindle Edition (£8.99)]. ''A 'free' epub can be googled for, *NOT* linked here due to dubious legality.''<br />
<br />
'''[https://archive.org/details/03screwcuttinginthelathe Screwcutting In The Lathe]''', by Martin Cleeve (a pen-name of Kenneth C Hart), Workshop Practice series #3, ISBN-13: 9780852428382<br />
<br />
'''[https://archive.org/details/15workholdinginthelathe Workholding in the Lathe]''', by 'Tubal Cain' (a pen-name of Tom Walsh), Workshop Practice series #15, Argus Books, ISBN-10: 0852429088<br />
<br />
'''[https://archive.org/details/20metalworkandmachininghintsandtips Metalwork and Machining Hints and Tips]''', by Ian Bradley, Workshop Practice series #20, ISBN-13: 9780852429471<br />
<br />
'''[https://archive.org/details/38toolandcuttersharpening Tool and Cutter Sharpening]''', by Harold Hall, Workshop Practice series #38, ISBN-13: 9781854862419<br />
<br />
'''[https://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpaperT204.pdf Cutting Fluids]''', by EC Bingham, NIST Tech. Paper No. 204, 1921<br />
<br />
=== WWW resources ===<br />
==== Mini-lathe Specific ====<br />
There's a *LOT* of mini-lathe info online. Notable sites include:<br />
* http://www.mini-lathe.com/ - A major Realbull/Sieg mini-lathe resource.<br />
* http://mikesworkshop.weebly.com/lathe-modifications.html - many mods including carriage DRO autostop, and variable speed leadscrew motor drive, cross-slide motor drive, etc. He also has a page with a bunch of accessories, toolholders etc. - http://mikesworkshop.weebly.com/lathe-accessories-and-tooling.html<br />
* http://andysmachines.weebly.com/variable-speed-controls.html - Scroll down to the 'UPDATE' section for the schematic of a very similar SCR speed control board. It also has the schematic for an earlier version of the Auxiliary Control Board (aka: 'Filter' board).<br />
* https://www.youtube.com/watch?v=WbJM9ooveo8 - A video tour of a very very similar mini-lathe. Significant differences: ours has a 4" longer bed, a quick change toolpost, a different tailstock, no DRO (apart from basic spindle speed, so skip 16:12 to 28:50 in the video), larger chucks and a carriage lock.<br />
<br />
==== Forums ====<br />
''with publicly accessible archives''<br />
* https://groups.io/g/7x12MiniLathe - Mini-lathe specific, active<br />
* https://www.hobby-machinist.com/forums/mini-lathe-mini-mill-information.220/ - active<br />
==== Youtube Playlists & Videos ====<br />
* Blondihacks: [https://www.youtube.com/playlist?list=PLY67-4BrEae9Ad91LPRIhcLJM9fO-HJyN Lathe Skills] (playlist) - "This is an educational series to help you learn to use your metal lathe. Watch them in order for best results! Satisfaction not guaranteed, especially if you're a cranky sort of person."<br />
* Frank Hoose (Minilathe.com) has a couple of relevant Youtube playlists:<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn7ON0jGM5UbM-KZDT56MOIp Mini Lathe Operations]<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn4nGRZaVq3wTOlvZNOmdAZ2 Mini Lathe Overview]<br />
<br />
==== General Machining ====<br />
* https://www.machiningdoctor.com/ - "THE #1 MACHINING TECHNICAL HUB"<br />
<br />
==Projects==<br />
[[File:VESA mount.jpg|thumb|Machined VESA mounting plate (left) and plate from Dell monitor stand it must match (right). The translucent washer shows the size of the original center hole.]]<br />
* My first faceplate project was boring out the center hole in a VESA mounting plate to adapt it to fit onto a surplus Dell 1708FP monitor stand. The part was centered using the tailstock dead center engaging with its original center hole. I clamped the part with studs and penny washers on the driving side of two opposite corners, with cap screws in the next slot round to trap the corners under the clamping washers, then withdrew the tailstock and dead center. After machining out the bore, I used the tip of the tool, rotating the chuck by hand, to scribe a circle for laying out the bolt holes. I finished off laying out and drilling the bolt and locating holes by hand at home, fitted it to the stand, and mounted the 2nd hand LG 24" widescreen monitor.<br />
<br />
* Another ultimately unsuccessful project was fly cutting aluminum flat bar to thickness to make custom shims for the set of carbide insert tools, for the four way toolpost. The 8 mm shank tools need ~2.5 mm shim stacks, and the 6 mm shank tools need ~4.5 mm shim stacks. Ideally I'd machine single shims, but the only stock I've got handy cleans up to only 3.2mm, and some fine shimming may be needed to fine-tune the tool height.<br />
<br />
: After sorting out the clamps so they were no longer twisting the aluminum flat bar stock, and switching to the short 45° turning SCMT06204 insert tool in the four way toolpost, to improve rigidity and get a well controlled tip radius, the finish was much improved. I'm still having problems getting an even thickness and am getting approx. 0.05mm variation, I suspect due to the aluminium bar stock distorting due to internal stresses as its surface is cut away. ''ToDo: try supergluing the stock to the faceplate before clamping to further reduce chatter and stop the warping.''<br />
: Looking back on this project a year later, its fairly obvious that the thickness variation was probably due to faceplate surface runout due to the damaged spindle nose.<br />
<br />
* Raphael has been working on a steel rocket nozzle with some assistance from myself. We have set up the rough cut chunk of ~ 50mm steel bar, faced both ends (to 50mm length) and turned the OD to 49mm to clean it up. Its going to need through drilling, probably some boring, and quite a bit of detail work on the OD. It will then need to be transferred to a jig in the drill press vice to allow a pattern of angled traverse holes to be drilled with acceptable accuracy.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=File:Lathe_Induction_Bushing.pdf&diff=17623File:Lathe Induction Bushing.pdf2024-02-18T13:09:22Z<p>IanM: Engineering drawing of a flanged bushing for Lathe Induction training. Uses ~15 mm of 12 mm / 1/2" dia. brass stock. Created by Ian.M for RML.</p>
<hr />
<div>== Summary ==<br />
Engineering drawing of a flanged bushing for Lathe Induction training. Uses ~15 mm of 12 mm / 1/2" dia. brass stock. Created by Ian.M for RML.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=OpenSCAD_to_Laser_Cutter&diff=17622OpenSCAD to Laser Cutter2024-02-18T00:19:56Z<p>IanM: /* Kerf (cut width) compensation */</p>
<hr />
<div>''The RML [[Laser cutter]]''<br />
<br />
[https://openscad.org/ OpenSCAD], although normally used for 3D modelling, can be used for 2D modelling for laser cutting. It can render 2D geometry directly and export to .dxf, suitable for RDWorks import, or you can use the projection() module to [https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/3D_to_2D_Projection slice or flatten 3D geometry] to get 2D geometry to render for export.<br />
<br />
== Known issues ==<br />
OpenSCAD does not generate curves as arcs, so they are always built up of straight line segments.<br />
RDWorks does not like curves built of excessively short straight line segments, and thus will not cut holes that have been rendered at too high a resolution. If you zoom in in RDWorks you'll see the problematic holes have a dashed or broken outline. If your design has small circular holes, check the job in RDWorks Preview mode - problem holes will be shown with a very thick outline and will be partially or completely skipped when you run the simulation. Increasing the minimum arc segment length in OpenSCAD, either directly or by reducing the number of segments will resolve the issue. If you need the higher resolution elsewhere, simply override your global $fn or $fs for the problematic holes.<br />
<br />
== Hints & Tips ==<br />
=== Kerf (cut width) compensation === <br />
You can easily extend the outline of objects and reduce hole sizes to (partially) compensate for the width of the laser cutting beam. Note that the kerf (cut width) is not uniform from top to bottom and will vary slightly with position on the laser cutter bed, material and cutting parameters, and focus. To do so, measure or estimate the kerf, and in OpenSCAD do:<br />
<pre><br />
$kerf=0.15; //Edit in your measured kerf here!<br />
<br />
offset(delta=$kerf/2)){// move edge cuts out and hole cuts in by half beam width<br />
//2D geometry goes here<br />
}<br />
</pre><br />
''offset(delta) is a bit more computationally efficient than minkowski() with a circle as it doesn't round corners.''<br />
<br />
=== Kerf Measurement Jig ===<br />
[[File:Lasercut Kerf Calibration.png|thumb|Kerf measurement jig]]<br />
This jig consists of nine rectangular tiles in a frame to let you average the measurement over the ten parallel cuts. Four of the tiles are drawn as such, but the other five are generated as the gaps between them, which guarantees there is only one cut line separating them.<br />
<br />
To measure the kerf, cut this jig from some scrap of the same material as your work, in approximately the same position on the laser cutter bed. Next, carefully transfer to a flat surface without rearranging or flipping any tiles or the frame ''(masking tape helps!)'', and mark the frame and all the tiles with a continuous diagonal pencil or marker line so you can subsequently be certain none have been inadvertently flipped or rotated.<br />
<br />
The actual measurement is taken by sliding all the tiles towards one end and measuring the narrowest part of the resulting gap with a set of feeler gauges, then dividing the result by ten. The result is the kerf at the narrowest depth of the cut (usually the bottom). Assuming the cut has a wedge shaped cross-section ''(usually more or less true for surface focused single pass cuts, with enough power / low enough speed to cut through cleanly with no hanging fibres)'', you can approximately measure the widest part of the cut by flipping every other tile starting from one end and re-measuring as above.<br />
<br />
[[File:Lasercut Kerf Calibration.zip]] ''including .dxf and .rld formats for non-OpenSCAD users''<br />
<br />
== Recommended Libraries for laser cutting ==<br />
https://github.com/bmsleight/lasercut - B. M. Sleight's Lasercut library handles extracting 2D geometry from components of a 3D model generated using its modules, and 'plating' the result for laser cutting. Has limited kerf compensation. It also can generate various types of interlocking joints, ranging from simple matching tabs and slots, up to complex twist into place locking joints, + notched slots for captive nuts. Unfortunately it doesn't make it easy to do finger to mid-sheet T joints. Requires Python 3. If you are an OpenSCAD power user, you may well find it easier *NOT* to use it for simple finger to T joints, but instead to add code to 2D 'plate' your own 3D models sheet sides.<br />
<br />
As OpenSCAD has no provision to interrogate the geometry of the object it is rendering, Lasercut has to work by getting the panels comprising the object to output their own 2D geometry as they are constructed, then parsing the console output with a clever script to generate the required 2D vector or openSCAD file. That means that parts generated or modified by 'vanilla' or BOSL2 OpenSCAD wont be rendered in the script's output, which although a limitation, can also occasionally be an advantage if you are constructing an assembly of laser-cut and 3D printed (or bought) parts.<br />
<br />
Also see the Hackaday article about it: https://hackaday.com/2022/01/02/an-openscad-library-for-all-your-cnc-cutting-needs/</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_%C2%A399_ZHUHAI_CTC_DiY_I3_3D_printer&diff=17620Ian M's £99 ZHUHAI CTC DiY I3 3D printer2024-02-14T15:29:48Z<p>IanM: /* 15 December 2023 */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br><br />
<br />
The ZHUHAI CTC DiY I3 Pro B 'Prusa' clone printer is rather similar to RML's [[Geetech I3 Pro B]] except with a laser cut plywood frame instead of acrylic, and cheapened in many key areas, which I'm working on upgrading. Its my personal 3D printer and is not kept at RML.<br />
[[File:Ian's CTC I3 After BLtouch upgrade.jpg|thumb]]<br />
== The DiY kit and the build ==<br />
Here's CTC's official build video: https://youtu.be/PSzcU48wczk<br />
=== Differences on my printer ===<br />
* IEC power inlet (Video has direct attached mains lead)<br />
* Bed levelling screws have countersunk heads so there are no obstructions at the bed corners<br />
<br />
=== Hints & Tips that didn't make it into the build log ===<br />
* Buy a pack of M3 washers and insert one in each T-slot in the frame, between the nut and the wood it bears on, to spread the pressure and prevent the nut chewing the wood.<br />
<br />
* A pair of M8 nuts can be used to 'hang' the lead screws and gantry assembly from the top of the frame while working on the steppers or shaft couplers.<br />
* Put a *VERY* large cable tie right round the body of the extruder and X steppers, with the tail coming straight up at the back of the extruder, and straight down off the X stepper, then cable tie the wiring to the big tail to anchor it before you spiral wrap, Leave the big tail full length inside the spiral wrap to stiffen the loom near the motor. A similar large cable tie round the lower right board fan standoff, snug but not tight so it can pivot on the standoff, can be used to anchor the lower end of the X loom.<br />
<br />
* The 2004 control/display PCB is probably being warped by its plywood frame and the absence of spacers between the board and the back not allowing for the solder joints with slightly protruding header pins. Dismantle it and shim for clearance behind the board with nuts/washers/etc. taking care not to short anything. You may need to file out the bolt holes in the ply so the board fits properly without being forced into a curve before reassembling and mounting it.<br />
<br />
== Build log from my posts on the RML Telegram group ==<br />
''Currently, a mostly verbatim copy of my 3D printer related posts, with some corrections and additions to my posts + some responses to my posts from other members. If you feel I've misrepresented what you said, or you don't want to be quoted, and you don't have edit rights here, PM me on Telegram!''<br><br />
<br><br />
''ToDo: Transfer more stuff from Telegram here and edit it into a coherent project writeup.''<br />
<br />
=== 6 Jan 2022 - Arrival and initial mechanical assembly ===<br />
A cheap (£99) Prusa i3 clone 3D printer kit should be landing on my doorstep later on this afternoon . . .<br><br><br />
{<s>photo from manual</s>, ''not posted here due to copyright''}<br><br><br />
It arrived.<br><br />
Its actually a ZUHAI CTC DiY I3 PRINTER with a wooden frame, and an ANET A8 v1.5 clone controller board. That’s more or less what I expected as a *real* Prusa for under a ton just isn't happening unless its a BER parts mule. Next: dig through the documentation, such as it is . . .<br><br />
<br><br />
''Mike: “Hi Ian, is it £99?”''<br><br />
<br><br />
Yep. It was £99 from Amazon. https://www.amazon.co.uk/gp/product/B015GDDXJA<br />
<br>I've done the full mechanical assembly, and knocked off for the night *WITHOUT* starting any wiring.<br><br />
<br><br />
For anyone else contemplating this one, beware: the rails are steel tube, not rod, it has plastic slider bushings not linear bearings, and the Z drive nuts are aluminum, not bronze or brass. Also the filament drive is not adjustable for pressure, and there are very few free GPIOs on the controller available for custom stuff. (There's the three SPI pins of the ISP port J3 ''if you disable SD card support'', one pin on the LCD connector reserved for a beeper on some display boards, and I suppose you could free up two more analog capable pins and UART1 TX & RX if you added an I2C LCD driver board.)<br><br />
<br>[[File:Ian's CTC I3 IEC Boot + extra clamping nuts on Y strut.jpg|thumb]]<br />
* '''CAUTION: THERE ARE EXPOSED MAINS TERMINALS'''<br><br />
As soon as I've got it dialled in I need to print a cover for the back of the IEC connector, and do something better than the flip-up cover over the PSU mains terminals. ''I ended up putting a rubber boot made from bicycle inner tube over the back of the IEC connector secured with cable ties as it was just too unsafe adjusting the right rear bed levelling screw without insulation there.'' <br><br />
<br><br />
I've already improved the rigidity considerably by adding four M8 nuts and washers to clamp the vertical frame to the M8 allthread that joins the front and back end plates. If you do the same, you *MUST* align the frame and endplates on a dead flat surface<sup>'''*'''</sup>, and as you tighten the new nuts, use a straightedge to check you aren't bowing the vertical frame's lower cross-member. Check you get the front on again dead square. While you are in there, put a nut in the hex hole in the Y axis belt tensioner so the bolt stays put while you adjust the wing nut.<br><br />
<br><br />
I'm sure I'll be buying other bits for it, once its up and running. e.g. flexible couplings + bearing balls for thrust for the Z screws to reduce shimmy, cheap but real linear bearings, and an all metal adjustable pressure filament drive upgrade kit.<br><br />
<br><br />
'''''<nowiki>*</nowiki> The flatness of the assembly surface is crucial - 0.2 mm lift of one side of the front plate relative to the rest of the frame, becomes 0.1 mm of varying bed tilt as the bed moves from min. Y to max. Y or visa-versa, giving the illusion the bed surface is saddle shaped, but also resulting in increasing lateral distortion the greater the print height is above the bed rails. Once assembled flat and true, it *should* be operated on an equally flat surface to maintain alignment, but if your table is of questionable flatness, the printer can be shimmed under its frame, and front and back plates to maintain six points of contact, and its position on the table marked to remind you to keep it in the position you've shimmed flat for it.''''<br><br />
<br><br />
<br />
=== 9 Jan 2022 - Wiring and problems ===<br />
Doing the CTC I3 3D printer wiring neatly took most of Saturday afternoon. Then it didn't work! 😢<br><br />
''Back in January, the extra board above the main board (to combine the normal Z limit switch and the BLtouch probe output), and all wiring to it was not present, and only the standard single short-lever Z limit microswitch was fitted.''<br />
[[File:Ian's CTC I3 Boards and Wiring.jpg|thumb|The main board and wiring]]<br />
<br><br />
Diagnosing its ills took the whole evening - one of the Z steppers had a broken wire. After carefully teasing the offending pin out of the stepper cable connector, I cleaned out the old crimp and soldered it and both steppers stepped uncoupled. It helps to use a couple of M8 nuts, put on the tops of the Z screws to hold them up so the X axis doesn't have to be dismantled when working on the Z steppers and couplings. The left side was binding and the right side wasn't a whole lot better. Turns out the laser cut bracket motor mounts don't line up with the screw when the Z axis is near the bottom. It’s fiddly but it is possible to remove the motors without extra dismantling. Some careful filing to elongate the mounting holes to line up the motor and final tightening after the coupling was slid over the screw end, and it no longer binds.<br> <br />
<br><br />
However, it still failed to home. 😾 Investigating the limit switch signals found the odd one out was the Y axis which read as homed when it wasn't. The switches are all NC microswitches, and I was getting ready to replace it, when I found its connections failed the tug test on both wires! The wires were broken under enough OEM heatshrink to confuse the issue. Resoldering them and applying new heatshrink fixed that and it now homes.<br><br />
<br><br />
I suspect the motor wire was a bad crimp, and the switch wires most likely broke because they were 'flapping in the breeze' while the bed, Y axis and lower frame assembly was being packed and shipped.<br><br />
<br><br />
Finally I was able to test the full range of motion of all axes, do a quick & dirty manual bed levelling and set the Y zero limit screw as low as seems reasonable. (I had it high to avoid crashing the nozzle earlier.) Selecting PLA warmup showed both the heated bed and the hot-end were working, and stabilized at their setpoints, though I'm getting an initial 10 deg C overshoot during hot end warmup, so it probably needs some tuning.<br><br />
<br><br />
I then tried to load and feed filament - no joy - it didn't want to feed, and when I manually encouraged it all I got for my trouble was a clogged hot-end. Taking the extruder off, dismantling it and careful reassembly of the feeder got it feeding, but I still had the clog to deal with.<br> <br />
<br><br />
I suspected the PTFE tube liner in the heat-break wasn't seating properly, which is what probably caused both the feed problem and the clog. I dismantled the hot-end and extracted the PTFE tube - clogged solid and fatter than the throat at the top of the heat-break tube. I managed to press the clog out with the stem of an Allen key, then close inspection of the PTFE tube found neither end was square. I shaved the better end square, and chamfered the entry to the other end by twiddling a sharp drill bit to stop the filament catching on its edge. Clearing the nozzle was a PITA, eventually it succumbed to a cold pull done off the hot end, supporting the nozzle with a small ring spanner and heating it with a lighter.<br><br />
<br><br />
I then bench tested the extruder, and it now feeds and extrudes, (manually using the axis menu). Its really fiddly to bolt back on to the X carriage without stripping it to separate the bracket, but after a lot of faffing about and some rather unparliamentary language I got it back on properly, leaving it loaded with filament from the bench test.<br><br />
<br><br />
Finally I checked it still homes and that the bed levelling hadn't gone too far out while I was working on it, and shut it down for the night.<br><br />
<br><br />
ToDo: Try printing something!<br><br />
<br><br />
<br />
=== 9 Jan 2022 - Q&A with Ian B, dangerous mains plug, and sellers 'bait & switch'! ===<br />
''Ian B: “Ian, that's quite a log of problems solved. It certainly shows a lack of QC from the manufacturer.''<br><br />
<br><br />
''It seems you've approached each fault methodically. (I would expect nothing less from you.) Heating the extruder with a lighter is something I've never heard of before, useful technique.''<br> <br />
<br><br />
''I wish you luck with the first print. Keep it small and simple.''<br><br />
<br><br />
''Then I wish you ongoing luck with all subsequent prints, too.”''<br><br />
<br><br />
If you try my lighter trick, to avoid bouncing a hot-ish nozzle round the room, it would probably be a better idea to screw the nozzle into a M6 nut, and hold it in mole grips with card for thermal isolation from the grips, and clamp the grip handles flat in a vice. The nut will also increase the thermal mass making the whole process more controllable.<br><br />
<br><br />
I forgot to mention the illegal ('The Plugs and Sockets etc. (Safety) Regulations 1994' - UK Statutory Instruments 1994 No. 1768) undersized and unfused mains plug on its supplied IEC lead. Its pins were so far undersize that there was no retention force in a standard socket!<br><br />
<br><br />
John Ward on these counterfeit leads & plugs: https://www.youtube.com/watch?v=9KMrWupFQt4<br />
<br><br />
AITA if I try to nail Amazon's balls to the wall for "not as described" and the illegal mains lead? It was still a reasonably good deal as supplied . . .<br><br />
<br><br />
==== Description from Amazon product page at time of sale ====<br />
* Brand Josef Prusa<br />
* Material Carbon Fibre<br />
<br />
'''Product description - Technical specifications'''<br />
* Print area - 8x8x8 inches (20x20x20 cm)<br />
* Open frame design for easy use<br />
* Integrated LCD for use without a computer<br />
* SD card support (8GB included) and USB port<br />
* Geniune E3D 1.75mm hotend and RAMBo mini motherboard<br />
* Easy multicolor printing feature based on layer height<br />
* Layer height from 50 microns<br />
* Heated print bed for warpless printing from any material<br />
* Supported materials - PLA, ABS, PET, HIPS, Flex PP, Ninjaflex, Laywood, Laybrick, Nylon, Bamboofill, Bronzefill, ASA, T-Glase, Carbon-fiber enhanced filaments...<br />
* Step size in X/Y axes - 10 micron<br />
* 2 lbs (1 kg) Silver PLA included<br />
<br />
==== DISCREPENCIES (so far) ====<br />
* Not a genuine Josef Prusa printer - its a ZHUHAI CTC ELECTRONIC CO. model.<br />
* Plywood frame, and no carbon fibre components<br />
* Less than 20cm X travel - measured 18.6cm from mechanical limit to limit<br />
* No SD card supplied<br />
* Not a "Geniune (sic) E3D 1.75mm hotend" - its got a bargain basement generic clone hotend<br />
* Not a "RAMBo mini motherboard" - its got an Anet A8 v1.5 clone, with a lesser MCU, no max. endstop switch inputs, one less thermistor input, and only three PWMed MOSFETs, so only one controlled fan can be connected.<br />
* No "2 lbs (1 kg) Silver PLA included" - Three sample coils of approx 12m each, total under 120g supplied<br />
<br />
=== 12 Jan 2022 - First Print and another defect found ===<br />
The CTC I3 3D printer prints!<br><br />
<br><br />
I'm currently using Cura 3.2.1, and so far have done a test cube and am currently trying an Arduino Mega2560 'bumper' generated from an OpenSCAD library. I aborted the first run after a couple of layers to have something to check against the Arduino board - it looks reasonable, so I'm doing a proper run, and hoping it comes out well enough to use. <br><br />
<br><br />
More defects found! The X tensioner bolt has a really crappy rolled thread and wont hold in the wing-nut. An ordinary M3 nut on it has just enough grip to be usable. I need to replace it with a long M3 machine screw, so I can get a nut into the tensioner body to hold it, so it doesn't spin when I adjust the wing nut. ''Subsequently fixed with a length of M3 stainless allthread, with the end mushroomed slightly and a hex nut Loctited on flush to effectively make that long machine screw.''<br><br />
<br><br />
Next job will be to see if I can backup the existing firmware then look at what it takes to get Marlin built for an Anet A8 v1.5 controller, and configured for the CTC I3 3D. Once I've got a usable 'stock' firmware, I can look at the upgrades I want to do, as even swapping out the extruder's filament drive mechanism would need me to reverse the extruder motor (due to the handedness of the drive assembly required to clear the mounting bracket). ''I did succeed in making a backup using AVRDUDE and a PICkit 2.''<br><br />
<br><br />
Edit: The Arduino 'bumper' is usable - a bit tight, so either my X and/or Y scaling is fractionally off or the Elegoo Mega2560 clone PCB is fractionally oversize.<br><br />
<br />
=== 17 Jan 2022 - Running my own Marlin build and finding/fixing more mechanical defects ===<br />
Progress of a sort on the CTC DiY I3 3D printer . . .<br><br />
<br><br />
The stock firmware is fairly sucky, ''probably doesn't have thermal runaway protection,'' and CTC don't appear to have released their source :( so I've been working on configuring a Marlin 1.1.9 build to run on it. Its only got an ATmega1284P ''(which has 128K Flash program memory)'', and I'm currently at 95% used, so Marlin 2.0.x isn't really a good option as I'd have to pare it down too much. Unfortunately those who have been there before me had a DiY I3 with a different controller so its been a fight to hack the config files into a usable state for it. I've still got some FUBARed Z motion defaults I need to sort put before it tries to get the Z axis to dig for Australia again! Maybe I should restore the backup of the original firmware and time some motions . . .<br><br />
<br><br />
In other news, there is supposedly no calibration table for its thermistors that's usably close, so I've had to generate one fudged from an Excel spreadsheet and some dodgy temperature measurements taken with a 1N914 diode stuffed up the hot end<br><br />
''My life was complicated here by the lack of any thermometer that could survive hot end temperatures.''<br> <br />
<br><br />
Bed Levelling needs some work, I'm trying to get manual mesh levelling up and running but it really *HATES* concave beds, as there is no option to automate moving to a safe height to clear the edge after homing off the edge of the bed. Various kludgy firmware hacks have been proposed, but I think a hardware hack is in order - use the Ymin limit switch to switch in a different height Zmin limit switch when its not over the bed, so it can be adjusted to home at a height that skims just clear of the [0,0] bed corner, then can go -Z by up to a mm or so before the regular Zmin limit trips, to allow it to level mesh points 'in the valley' without a Z probe.<br><br />
<br><br />
To that end, has anyone got a *looooooooong* lever SPDT microswitch hanging about? Flat lever and 20mm 2 hole body with terminals on the bottom preferred. Also, ideas for a cheap-skate Z probe wouldn't go amiss.<br><br />
<br><br />
''In the end I found some suitable switches on Amazon and built my dual switch Z axis limit 'Z-hop' mod. It fits in place of the original switch and if homing, with the nozzle just off the front of the bed provides a Z limit a little over 0.5mm higher than that over the bed, with the difference adjustable by bending the long switch lever. Some months later I found a BLtouch Z probe clone far cheaper than I could build any sort of deployable probe.''<br><br />
<br> <br />
Also, has anyone got experience automating acquiring temperature calibration table data for Marlin? I'm thinking maybe a Type K thermocouple bonded into a knackered brass extruder nozzle with high temperature cement, and some sort of PC interface for it, talking to Marlin with M105 SHOW_TEMP_ADC_VALUES enabled. Take it up in steps, reading the ADC and temperature for each till its good & hot, then log the cooling curve and check it matches reasonably well, and finally spit out a table in Marlin header file format.<br><br />
<br><br />
* '''CAUTION: Belt tensioners destroy themselves!'''<br />
The idiots at CTC used D shaft offcuts for the belt tensioner pully shafts and used the drive type pully for the idlers so the shaft turns with the pully. Running in a plastic hole with no bushing it acts as a D reamer and tries to chew its way back to the motor! A reasonable bodge fix is to flatten four M5 split washers ''(two for each tensioner)'', and wedge them in the recesses either side of the tensioner body, with the splits towards the tension screw. That's steel on steel, but if kept greased is better than steel D reamer on plastic! Long term it needs decent ball bearing tensioners. ''[[#18 June 2022 - Upgrading the belt tensioners with ball bearings|See below.]]<br><br />
<br />
=== 20 Jan 2022 - Flexible Z screw couplers ===<br />
The original rigid couplers between the Z stepper motors and the Z screws were unsatisfactory, as any misalignment directly pushed the gantry laterally resulting in prints with pronounced Z banding. I therefore bought some helical flexible couplers for coupling 5mm to 8mm shafts, and installed them with a 7mm ball bearing inside each to transfer the axial thrust loading from the Z screws direct to the motor shaft to minimize Z bounce. I had to shim the lead screws (which are ordinary M8 allthread) with aluminum cut from a drink can to get them concentric in the 8mm end of the coupler as their OD is slightly undersize.<br />
<br />
Although there was a notable improvement in print quality once I had carefully adjusted the coupler alignment, it wasn't a total cure as the lead screws are still shimmying enough to wobble the gentry at low Z heights. I need to decouple the drive nuts from the gantry, by flipping them the other way up and adding a thrust bearing that doesn't constrain them radially between them and the gantry. The nuts will also require anti-spin arms, and as the screws will no longer have any constraint above the couplers, they'll need top bearings.<br />
<br />
I also added a silicone 'sock' over the hotend to improve its insulation and reduce the hot touch hazard to just the nozzle itself.<br />
<br />
=== 10 Feb 2022 - Upgrades ===<br />
CTC DiY I3 3D printer progress: All slider bushings have been replaced with real linear bearings and I'm now printing a 3DBenchy in black PLA on 1.8mm glass (cut from a broken picture frame), with cooling<sup>'''*'''</sup>, using Cura 3's 'stock' slicer settings: Fine (0.1mm layers, 20% infill). So far its looking good.<br><br />
<br><br />
I need to do something about a proper enclosure for it as the ambient temperature is a bit on the low side.<br><br />
''Currently its in a cardboard enclosure made from a very large cardboard Amazon box, with a thin plastic sheet curtain front. This is a fire risk, and replacement with a non-combustible enclosure (e.g. made from plaster wallboard) or flame-retardant enclosure should be a high priority. Unfortunately running without an enclosure isn't a good option due to the number of print failures I've had due to warping caused by drafts resulting in loss of bed adhesion.''<br><br />
<br><br />
'''''<nowiki>*</nowiki> I added a 50mm centrifugal part cooling fan, stuck onto the back of the extruder motor using 3M (clone) VHB tape, with a thin aluminum tapered duct aiming at the extruder nozzle. This fan is connected to the only software controlled fan port on the Anet3D controller - FAN1. (FAN2 is permanent 12V, used for controller board cooling.) The extruder cooling fan is now wired in parallel to the hot-end heater. ToDo: design and build an extruder fan run-on circuit so sit starts when the heater is first activated, then continues to run to keep the top of the heat-break cool till the hot-end is below 100°C (or maybe simply a retriggerable timer of several minutes).''''<br><br />
<br />
=== 13 Feb 2022 - Running out of program memory! ===<br />
I just managed to build Marlin v1.1.9 with UBL (unified bed levelling) to fit in a ATmega1284P (ANET 3D v1.5 board).<br><br />
<br><br />
Will I be using it? That's a hard *NO* because to get it to fit I had to disable just about everything else except thermal protection and minimal LCD menus. No SD support, no emergency parser, no cold extrusion prevention, no endstop interrupts, no G26 mesh validation print, no M503 and a host of other minor snips and vicious GCC size optimizations. I even rewrote the Arduino LiquidCrystal library with no 8 bit support to save another hundred bytes. Also it wont fit with *any* bootloader so the only option would be to use an AVR programmer and ISP. :(<br><br />
<br><br />
''Ian B: Seems that the ANET 3D board is seriously under-spec with that processor. It wouldn't have cost them much to fit a processor with bigger ROM.''<br> <br />
''Anyway, some say UBL is all it's cracked up to be. Just get your build plate physically level, as I'm sure you have.''<br><br />
(I suspect Ian B meant: "... UBL '''isn't''' all it's cracked up to be.")<br><br />
<br><br />
''Petr Cecil: Check the bigtreetech boards on the AliExpress I had one for about 12 quids in some sale, still running on it my ender 3''<br><br />
''They got much more memory''<br><br />
<br />
=== 16 Feb 2022 - More musings on bed levelling and program memory ===<br />
I was just looking at my options before building a Z probe. I've already got manual bed levelling with a 5x5 grid installed without disabling SD support or anything else nice to have, so I've just got to look at alternatives to full UBL. e.g. switch ''(from UBL)'' to AUTO_BED_LEVELING_BILINEAR with no other changes and it goes from needing 100% + 410 bytes more (than optiboot max user progmem) to only 62%, so I should be able to turn SD support back on + most of the nice stuff I pruned. Although a more capable controller would be *nice*, this *IS* only a £99 3D printer so its hard to justify spending for a good controller before I've even got all the mechanicals up to scratch.<br><br />
<br><br />
''My 3D printer build was then on hiatus for several months. I did do a couple of non-notable successful prints on its (questionably) manually leveled bed, and spent a fair bit of time teaching myself OpenSCAD.''<br />
<br />
=== 18 June 2022 - Upgrading the belt tensioners with ball bearings ===<br />
Previously:<br />
<blockquote><br />
* '''CAUTION: Belt tensioners' destroy themselves!'''<br />
The idiots at CTC used D shaft offcuts for the belt tensioner pully shafts and used the drive type pully for the idlers so the shaft turns with the pully. Running in a plastic hole with no bushing it acts as a D reamer and tries to chew its way back to the motor! A reasonable bodge fix is to flatten four M5 split washers ''(two for each tensioner)'', and wedge them in the recesses either side of the tensioner body, with the splits towards the tension screw. That's steel on steel, but if kept greased is better than steel D reamer on plastic! Long term it needs decent ball bearing tensioners.<br><br />
<br><br />
''[[#17 Jan 2022 - Running my own Marlin build and finding/fixing more mechanical defects|Ref: 17 Jan 2022 - finding/fixing more mechanical defects]]''<br />
</blockquote><br />
[[File:CTC Tensioner.png|thumb|Belt Tensioner]]<br />
Well I finally got and fitted MR85ZZ ball bearings to both belt tensioners on my CTC DiY I3 3D printer. The bearings are ludicrously tiny, 8mm OD, 5mm ID and only 2.5mm thick, which is only 1.5mm radially for both races and the balls between them, but that's what it takes to fit the bearing recess either side of CTC's 'factory' belt tensioner. Each bearing is held in its seat by a M3 screw next to the outer race, so they aren't going anywhere. I loctited the D shaft into the front X tensioner bearing so I shouldn't have any more failed prints due to it walking out of the idler pully.<br><br />
<br><br />
For anyone else contemplating the Zuhai CTC DiY I3, I couldn't find a STL (or any other model) of the tensioner anywhere, which as supplied is a wear part, and a rapidly wearing one at that, as the D shaft will chew the holes badly out of round in only a few hours printing unless you mod it so it isn't running edged steel on plastic, so (as usual) I modelled it in OpenSCAD, taking the dimensions as accurately as I could from the 'factory' tensioner. Get the tensioner model here: [[File:Tensioner4.zip]]<br><br />
<br />
=== 25 June 2022 - Testing a BLtouch probe ===<br />
<br />
I'm (slowly) working on adding auto bed levelling to my CTC DiY I3 3D printer.<br><br />
Here's an Arduino sketch to bench test a BLtouch/3Dtouch (or clone) levelling sensor, that lets you set probe states by single letter serial commands and reports the ZMIN output status, like this:<br><br />
<br />
*** BLtouch/3Dtouch probe tester ***<br />
D = Deploy<br />
T = Tswitch<br />
R = Retract<br />
S = Self test<br />
A = Alarm off<br />
? = read ZMIN<br />
The Arduino LED echoes the ZMIN state, ON=High / OFF=Low<br />
__________________________________________________________________<br />
________________#___________________________________#_#___________<br />
____________________###______####_______##########_________####___<br />
____####__________________________________<br />
ZMIN is Low (0.10V)<br />
____________________________######################################<br />
ZMIN is High (5.00V)<br />
#################_________________________________#_______________<br />
<br><br />
The sketch: [[File:BLtouch tester.zip]]<br />
<br />
=== 29 June 2022 - Mounting the BLtouch, and building Marlin to support it ===<br />
Slight progress on adding a BLtouch (clone) ABL sensor to my Zuhai CTC DiY I3, 3D printer. I've got the probe bracket printed and the BLtouch mounted on my printhead, with only 26mm Y offset, and nearly no X offset, without blocking access to the top of the throat in case of filament problems.<br><br />
<br><br />
''I drilled two 3mm holes just in from the front edge of the L bracket that holds the print head assembly to the X gantry carriage, in front of the mounting block that holds the hotend, to fix the bracket to with 2.5mm self-tappers from underneath into the printed probe bracket. My bracket was a little too low for the optimum probe height relative to the nozzle tip (above the tip by half the probe extension), so I ended up shimming it with a piece of wooden coffee stirrer. Once I touched it in with a black marker, you wouldn't know the shim is there, so although I fixed my OpenSCAD' bracket model, I'm going to be lazy/frugal and not re-printt it'<br> <br />
<br><br />
My printer uses an ANET3D v1.5 controller, so I've only got 128K FLASH on the ATmega1284P MCU to play with (half that on the usual ATmega2560 based boards), which has made building Marlin 1.1.9 small enough to fit with AUTO_BED_LEVELING_BILINEAR and BLTOUCH enabled quite a challenge.<br><br />
Even with aggressive GCC optimizations, (see links section below) it didn't quite fit until I disabled the boot screen. It was a choice between that and ditching Optiboot. :( <br />
Sketch uses 129932 bytes (99%) of program storage space. Maximum is 130048 bytes.<br />
Its a 'full fat' Marlin v1.1.9, with full menu, SD support and all the other nice to have goodies enabled., and I've still got 116 bytes left for any tweaks I want to add! 😁 <br><br />
<br><br />
''Petr Cecil: Just keep important features like thermal runaway protection on in marlin so you don't burn your home :))''<br />
<br />
''Yes, keeping thermal runaway protection was my highest priority. Without it, you are one loose screw away from a house fire! Many thanks to Petr for letting me use his crimper and JST connector parts to make up a JST XH-3 cable I badly needed for my BLtouch install. For anyone else needing JST XH (and duPont) crimping capability, here's what Petr recommends:'' <br />
https://www.amazon.co.uk/gp/product/B07VX6YGQ8/ ''and having used it, I would also recommend it.''<br><br />
<br />
=== 1 July 2022 - Wiring the BLtouch probe ===<br />
I've got most of the recabling done on my CTC DiY I3 for the BLtouch probe. I've spliced a three wire breakout cable for +5V Gnd and servo signal into my display ribbon cable, and re-done the loom to the printhead to add the BLtouch extension cables. All that's left to do is assemble the adapter board that Petr helped me with the JST cable for, mount and wire it, flash a BLtouch enabled Marlin build, and then I'll need to calibrate the Z offset.<br><br />
<br><br />
[[File:BLtouch combiner board.png|thumb]]<br />
... and here's the circuit I intend to use to combine use of the regular limit switch which is set up to inhibit Z movement approx half a mm below the bed surface (less than the flex in the gantry) so it cant 'dig for Australia' if for any reason the BLtouch wasn't deployed before homing.<br><br />
<br><br />
''I constructed the combiner board on Veroboard, laying it out using [https://veecad.com/ VeeCAD], from the schematic I drew up in [https://www.tinycad.net/ TinyCAD], mounted it to the printer and wired it up.''<br />
<br />
=== 5 July 2022 - Visualizing the bed levelling mesh ===<br />
Meanwhile, I've been futzing around with visualising 3D printer bed levelling meshes from Pronterface *without* pasting the M420 V mesh data into a website. Marlin comes with an OpenSCAD mesh visualiser called [https://github.com/MarlinFirmware/Marlin/blob/1.1.x/buildroot/share/scripts/MarlinMesh.scad MarlinMesh.scad], and it turns out that all you need to do to get external mesh data into that is to pass it in on the OpenSCAD command line as variables defined by -D override variables with file scope defined in the file. <br />
<br />
The prerequisites for using it are explained here, but if you've already got OpenSCAD installed and are using mesh bed levelling, you'll only need to skim this: https://3dwork.io/en/visualize-3d-mesh/<br />
<br />
To do this from Pronterface, with a hard coded mesh, as I hadn't figured out the M420 mesh parsing yet, put MarlinMesh.scad in the printrun directory and (on windows) in Pronterface send:<br />
<br />
!os.system('start /max "" "C:\Program Files\OpenSCAD\openscad.exe" MarlinMesh.scad -D $vpd=800 -D measured_z= <br />
[[-0.086,-0.045,-0.037,-0.046,-0.167,-0.292,-0.421],[+0.034,+0.038,-0.002,+0.017,-0.017,-0.121,-0.413], <br />
[+0.122,+0.098,+0.162,+0.034,-0.069,-0.234,-0.472],[+0.205,+0.196,+0.120,+0.071,-0.007,-0.149,-0.467], <br />
[+0.175,+0.174,+0.102,+0.010,-0.130,-0.313,-0.587],[+0.194,+0.189,+0.116,+0.034,-0.042,-0.170,-0.568], <br />
[+0.128,+0.089,+0.032,-0.033,-0.168,-0.373,-0.594]]')<br />
<br />
Note that this is currently Windows only, as the os.system() command string to launch OpenSCAD and return immediately:<br />
'start /max "" "C:\Program Files\OpenSCAD\openscad.exe" '<br />
will be very different under LINUX or OSX. The rest of the command line should be the same.<br />
<br />
Also I would strongly recommend editing the default mesh in MarlinMesh.scad (lines 24-30) to be a minimal 'null' mesh:<br />
measured_z=[[0,0],[0,0]]; //minimal mesh<br />
to make it obvious if your mesh data hasn't been passed in successfully.<br />
<br />
ToDo: Write a script to send G420 V to the printer and parse the returned mesh data into a string containing the mesh in the above OpenScad list of lists format, that can simply be appended to the os.system() command line after the -D measured_z=<br />
<br />
''Later that evening:''<br><br />
I've written and tested the Pronterface macro to launch MarlinMesh.scad from Pronterface with the printer's current MBL mesh from a M420 V report of the form:<br />
Bilinear Leveling Grid:<br />
0 1 2 3 4 5 6<br />
0 -0.086 -0.045 -0.037 -0.046 -0.167 -0.292 -0.421<br />
1 +0.034 +0.038 -0.002 +0.017 -0.017 -0.121 -0.413<br />
2 +0.122 +0.098 +0.162 +0.034 -0.069 -0.234 -0.472<br />
3 +0.205 +0.196 +0.120 +0.071 -0.007 -0.149 -0.467<br />
4 +0.175 +0.174 +0.102 +0.010 -0.130 -0.313 -0.587<br />
5 +0.194 +0.189 +0.116 +0.034 -0.042 -0.170 -0.568<br />
6 +0.128 +0.089 +0.032 -0.033 -0.168 -0.373 -0.594<br />
echo:Bed Leveling Off<br />
echo:Fade Height Off<br />
<br />
[[File:Bed mesh.png|thumb|My poor bed looks like a map of the Himalayas!]]<br />
So I've now got a Pronterface button that visualizes my bed live, without resorting to an online bed visualizer WWW site. 😁<br />
<br />
''Even with ABL enabled, its useful to let you see if your whole bed is out of whack' and could benefit from adjusting its levelling screws to reduce the range of Z offsets the ABL has to compensate for.'' <br />
<br />
It is currently Win x64 only, as the command line to launch OpenSCAD is OS specific. It shouldn't be hard to change that for Linux or OSX.<br />
<br />
To add it to your own Pronterface, first put MarlinMesh.scad in your Printrun folder, then paste the following into a new Pronterface macro:<br />
<pre><br />
!################# Bed Visulization macro #################<br />
!# Pronterface script to invoke OpenSCAD MarlinMesh with #<br />
!# the current MBL mesh returned by M420 V. #<br />
!# #<br />
!# (c) Ian.M 7/7/2022 #<br />
!# #<br />
!# "THE BEER-WARE LICENSE" (Revision 42): #<br />
!# "Ian.M" <https://t.me/Ian_M_2019> wrote this stuff. #<br />
!# As long as you retain this notice you can do whatever #<br />
!# you want with this stuff. If we meet some day, and #<br />
!# you think this stuff is worth it, you can buy me a #<br />
!# beer in return. Ian.M #<br />
!##########################################################<br />
!<br />
!import time<br />
!import os<br />
M420 V ; requst ML grid<br />
!time.sleep(1) # wait for it<br />
!idx=len(self.p.log)-1 # get last line in log buffer<br />
!idxf=None # error value <br />
!idxl=None<br />
!for x in range(idx,max(idx-20,0),-1): # iterate backwards <br />
! if self.p.log[x].find("Grid:")>8: # looking for 'Grid:', if found:<br />
! idxf=x+2 # set idxf to first (real) line of grid <br />
! break; # and exit loop<br />
! if self.p.log[x].find("echo:")==0: # looking for 'echo:', if found:<br />
! idxl=x-1 # set idxl to previous line till last line of grid is found<br />
!<br />
!#print("Debug: range "+str(idxf)+", "+str(idxl))<br />
!<br />
!if (idxf is None) or (idxl is None): # M420 failed<br />
! self.logError("Error: M420 failed")<br />
! return<br />
!if idxf>idxl: # M420 no grid<br />
! self.logError("Error: M420 did not return a grid")<br />
! return<br />
!<br />
!mesh="["<br />
!for x in range(idxf,idxl+1): # build list of OpenScad lists<br />
! mesh=mesh+"["+str(self.p.log[x])[3:].rstrip().replace(" ",",")+"]" # build comma separated list<br />
! if x<idxl:<br />
! mesh=mesh+"," # more to follow<br />
! else:<br />
! mesh=mesh+"]" # last one - end outer list<br />
!<br />
!# Build MMcmd for OpenSCAD installed in default location on 64 bit Windows.<br />
!# N.B use explicit 64 bit Program Files directory as Pronterface is a 32 bit application,<br />
!# so %ProgramFiles% returns %ProgramFiles(x86)%, which is the wrong folder.<br />
!MMcmd='start /max "" "%ProgramW6432%\\OpenSCAD\\OpenSCAD.exe" ' # change this OS dependent stuff!<br />
!MMparams="MarlinMesh.scad -D $vpd=800 -D measured_z=" # OpenSCAD command line parameters<br />
!# n.b. MarlinMesh.scad must be in printrun working directory<br />
!# -D defines an OpenSCAD constant for the session, overriding variables within the file. <br />
!<br />
!print("Invoking MarlinMesh.scad with this mesh.")<br />
!print("Exec: "+MMcmd+MMparams+mesh)<br />
!os.system(MMcmd+MMparams+mesh) #Execute it<br />
</pre><br />
<br />
''Edit: It turns out, that depending on your Pronterface version, you'll probably need to import '''os''' and '''time''' at the top of the macro. I've added them above.''<br />
<br />
=== 10 Sept 2022 - Z-screw wobble isolation ===<br />
Back in January I wrote:<br />
<blockquote><br />
The original rigid couplers between the Z stepper motors and the Z screws were unsatisfactory, as any misalignment directly pushed the gantry laterally resulting in prints with pronounced Z banding. I therefore bought some helical flexible couplers for coupling 5mm to 8mm shafts, and installed them with a 7mm ball bearing inside each to transfer the axial thrust loading from the Z screws direct to the motor shaft to minimize Z bounce. I had to shim the lead screws (which are ordinary M8 allthread) with aluminum cut from a drink can to get them concentric in the 8mm end of the coupler as their OD is slightly undersize.<br />
<br />
Although there was a notable improvement in print quality once I had carefully adjusted the coupler alignment, it wasn't a total cure as the lead screws are still shimmying enough to wobble the gentry at low Z heights. I need to decouple the drive nuts from the gantry, by flipping them the other way up and adding a thrust bearing that doesn't constrain them radially between them and the gantry. The nuts will also require anti-spin arms, and as the screws will no longer have any constraint above the couplers, they'll need top bearings.<br />
</blockquote><br />
<br />
At long last, I've completed the next stage of this, by laser cutting new top brackets and bearing retainers for 688ZZ ball bearings (8mm ID, 16mm OD, 5mm wide) from plywood, consisting of a redesigned bracket in 5mm ply, with a 16mm hole for the bearing which fits flush, surrounded by six tiny holes to fix retaining rings cut from 3mm ply above and below the bracket, each held by three tiny 2mm screws. I also laser cut the anti-spin arms for the Z-nuts from 5mm black Acrylic. All ply parts were spay painted matte black to match the rest of the printer frame. A Thursday evening well spent.<br />
<br />
I installed the parts and after some fiddling around managed to reduce the Z-screw runout, and got the screw centered well enough in the gantry end nut mounts not to touch and jerk. I still haven't got proper thrust bearings, and am making do with a stack of three M10 washers on the long end of each Z-nut, which have *NOT* been flipped as originally planned, as it looks like I'll need something other than the Z-screw to loosely constrain the thrust bearing. The washers are lightly greased so can slide over each other fairly readily<br />
<br />
After re-leveling (and some BLtouch calibration issues that were borking my first layer height), I finally managed to print a good test cube. Its got much less pronounced Z banding than before this upgrade. Hopefully adding ball thrust bearings will eliminate most of the residual banding. ToDo: design & fabricate cages for these bearings. The problem is a lack of space - I haven't got a lot of height between the top of the coupler and the bottom of the nut, and also, anything much larger than the 22mm OD of the nut flange would force me to move the part cooling fan and redesign its duct.<br />
<br />
''OpenSCAD design files and photos to follow''<br />
<br />
=== 06 January 2023 ===<br />
Another hiatus - I didn't need to do any 3D printing and was busy learning the RML mini-lathe.<br />
However I've made a small but significant improvement to the Z axis with nothing more than a few square cm of waxed paper! I took the backing paper off some double-sided tape, and wrapped one turn of the paper round the Z screw to make a spacer to fit inside the stack of washers. It sits over the lip on the end of the nut, inside the ID of the washer stack and helps the washer stack stay centered on the screw so none of them touch the screw, catch and jerk, but is so flimsy that the washers can still slide laterally with minimal extra force on the X gantry. A test cube showed much reduced Z banding vs the previous one from October.<br />
<br />
Its still not good enough as there is far too much runout at the bottom of the right-hand lead-screw which is shifting the X gantry support force to and fro enough to wobble it. Either I've got a bad coupler, its poorly assembled or there is a kink in the end of the screw where it was cut. Probably the best option will be to chuck the leadscrew in a soft collet in the lathe, get it running true, then turn the thread off the end of the leadscrew, shrink on a short bored out piece of steel rod, then turn that to 8.00 mm diameter, concentric to the screw, so I'm no longer trying to clamp on the threaded end.<br />
<br />
=== 13 December 2023 - Better Leadscrew Concentricity ===<br />
Some 3D printing of small parts this year, and several false starts with improving the lead screws. I spent quite a bit of lathe time doing test pieces with short lengths of M8 allthread. <br />
<br />
The soft collet idea was a non-starter as anything that grips on the thread tips gives poor concentricity. It turns out the answer is to wind a helix of soft iron or mild steel wire that fits the thread and grip on that so the grip is on the flanks of the thread. Also, shrink fitting was a bust - the precision and surface finish required to make it work for such small parts is right at the limit of RML's capabilities, and the tiny thermal mass gives only seconds to fit it and a fraction of a second to slide it home. The answer was loctite + machining to a push fit. 11 mm long, ~5.6 mm bore steel sleeves were made from 3/8" (9.5 mm) stock, and the thread turned down to fit for ~11 mm from the screw end. We don't have good enough bore measuring capability at RML so a test plug was turned to fit drilled bore to get the diameter to work to. Loctite was applied to both surfaces and the sleeve tapped on firmly. The OD was then turned to 8.00 mm and faced to 10 mm length, just cleaning up the screw end to get a true uniform end face, and the edge chamfered. <br />
<br />
I've got one leadscrew done, but time and machining mistakes were against me (I screwed up the 8.00 mm OD and had to turn the sleeve off and re-do it) so didn't get the second screw done. That's a job for tomorrow. <br />
<br />
Fitting and removing the screws now requires top corner plate removal. Run the gantry right up and hang it from the frame, then run the Z-nuts and their anti-rotation arms back down. Undo the coupler and take off the corner plate. The guide rod can be lifted and the anti-rotation arm swung clear, then the bottom end of the screw can be lifted off and slid down and forward till it can be slid out of the gantry end. Refitting is the reverse of removal.<br />
<br />
I've already got the left Z screw fitted, and the result is no obvious runout. Its highly dependent on the tightening sequence of the lower part of the helical coupler as excessive pressure with the split clamp causes the D shaft to go off center, so that should be lightly snugged up then the grubscrew tightened firmly on the flat. The grubscrew must be well aligned with the flat. Turn the other Z motor shaft to turn the one being assembled for access to the screws, as the coupler initially wont be tight enough to turn the motor.<br />
<br />
=== 15 December 2023 ===<br />
I machined the other screw yesterday evening and fitted it this morning, again with no obvious runout. I did some manual levelling to get the bed as near true to the Y rails as possible and the X gantry true to the frame and hopefully to the bed, then started automatic bed levelling, stored the resulting map, and started printing an XYZ calibration cube. The vertical sides came out nicely with no repetitive Z banding, so it seems my Z wobble problems are solved. However the waxed paper liner in the greased washer Z decoupler is a PITA to reinstall if disturbed, so I still need to look at thrust bearings, with some way to keep the cage from fouling the screw.<br />
<br />
=== 14 February 2024 ===<br />
Fitted [https://www.amazon.co.uk/dp/B07QLH2RQ8 F10-18M Thrust Bearings] to decouple the Z-nuts from the gantry.<br />
The bottom race is fitted upside down (flat side up) to let the race move radially, and the top race is replaced with a M10 washer, flat side down to allow more movement. The nut barrel comes about half way up the washer, so it shouldn't hang up on the Z-screw thread. <br />
<br />
''N.B. easiest access (without loosing Z-screw sync) is by removing the top corner plates and the fan screw anchoring the X stepper cable loom to get enough slack to lift the gantry off the top of the Z-screw. You will need some way to hang the gantry from the frame while working.''<br />
<br />
== - more to follow - ==<br />
<br />
== Some useful links ==<br />
* https://github.com/ralf-e/ANET-3D-Board-V1.0 - Schematic for an earlier version of the controller, near enough the same as the v1.5, and for the LCD2004 display/buttons board. Note that connector pinouts should be checked against the actual board before trusting them. e.g. I know the end stop connectors have pins 1 and 3 swapped vs the schematic.<br />
<br />
* http://lokspace.eu/anet-a8-wifi-mod/ - How to add printing over WiFi using an ESP-01 ESP8266 WiFi module and esp-link, by populating the Anet3D 'USB BLE' header + removing two zero ohm resistors. Level shifting is needed to get the 5V level ATmega TX pin down to 3.3V levels for the ESP8266 RX pin, hence the resistors on the carrier board. There's also no need for a USB UART adapter to flash the ESP8266, as the ANET main board has one of those. After dong the mainboard mod, simply take two short duPont F-F jumpers and link opposite corner pins of J8 the 'USB BLE' header, and use the mainboard's USB port. After flashing, remove the duPont wires, fit two jumper caps in the BLE position, and carry on with esp-link setup. Alternatively, use a Wemos D1 Mini clone which has all you need on-board except the level shifter, and its simple enough to solder two resistors for that. See my page [[WiFi 'tethered' Arduino robot]]<br />
<br />
* https://docs.arduino.cc/software/ide-v1/tutorials/PortableIDE - how to set up a portable install of the classic Arduino IDE which is strongly recommended for any existing Arduino user for building Marlin 1.1.x as you are likely to need to down-version the core and various libraries.<br />
<br />
* https://spiritdude.wordpress.com/2018/03/26/ctc-diy-prusa-i3-ctc-diy-i3-pro-b-most-affordable-3d-printer-2018/ - Another user's experiences with this printer.<br />
<br />
* https://ufj.ddns.net/blog/marlin/2019/01/07/reducing-marlin-binary-size.html - Turning on aggressive AVR GCC optimizations to reduce the size of the Marlin firmware, so it will fit in 128K program memory without having to prune too many desirable features.<br />
<br />
* https://all3dp.com/2/epic-3d-printing-fails-and-why-they-failed/ - some of the many ways things can go badly, ranging from potentially life-threatening, down through expensive and tedious, to mildly amusing.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=User:IanM&diff=17619User:IanM2024-02-14T15:15:45Z<p>IanM: </p>
<hr />
<div>[[File:IanM.jpg|thumb]]<br />
Hi, I'm Ian M,<br />
<br />
I'm just another RML member who's reasonably competent with electronics, including digital and MCUs, computers and mechanical stuff, after a couple of decades in the consumer electronics service trade.<br />
<br />
Other interests include sailing and boat maintenance - not that I do much nowadays - and reading SF. I used to be seriously into Sinclair 8 bit computers, and still have a fair bit of vintage Sinclair kit, in various states of operability. I also have a few vintage PCs.<br />
<br />
My motto should probably be: "Knows entirely too much about not enough subjects!"<br />
<br />
My main project last year (2022) was assembling, tuning and upgrading a [[Ian M's £99 ZHUHAI CTC DiY I3 3D printer|£99 3D printer]], and learning the necessary software to fully use it. <br />
<br />
I'm collecting my [[Ian M's OpenSCAD stuff|OpenSCAD notes here]].<br />
<br />
My [[Ian M's Lathe Notes|CJ18A mini-lathe notes are here]]. I'm now one of the Lathe trainers and maintainers. ''Thanks IanB for my Induction back in 2022.''<br />
<br />
I've also got some notes on [[Running Atmel Studio 4 on Win10]].<br />
<br />
Back in 2021, I was doing some stuff with a [[WiFi 'tethered' Arduino robot]].<br />
== Stuff that doesn't have its own page yet ==<br />
=== Plastics ===<br />
[[https://www.henkel-adhesives.com/be/en/applications/all-applications/how-to/bonding-plastics.html Hard to Bond Plastics?]] - Henkel (Loctite)'s notes on bonding difficult plastics, surface treatments etc.<br />
=== Soldering & Brazing ===<br />
[[https://archive.org/details/09solderingandbrazing/ Soldering And Brazing]] by 'Tubal Cain' (a pen-name of Tom Walsh), Workshop Practice series #09, Argus Books, ISBN-10: 0852428456<br />
=== Screw Fasteners ===<br />
[https://en.m.wikipedia.org/wiki/List_of_screw_drives Screw Drives] - Wikipedia's list of screw head/driver types. Good for finding the proper name for that obscure screw head so you can try to buy a driver for it!</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_Lathe_Notes&diff=17617Ian M's Lathe Notes2024-02-12T14:16:19Z<p>IanM: /* Mini-lathe Specific */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br />
<br />
''Currently these notes are semi-organized and non-authoritative. As I become more experienced with the RML CJ18A mini-lathe, I'm cleaning up, extending and reorganising them. Some lathe operating experience is assumed. If in doubt, '''*ASK*''' me, Andy H<sup>*</sup> , Jonathan H or another experienced minilathe operator!<br />
<br />
''* Andy H should be asked (for an authoritative answer) any questions involving RML usage policies or acquiring tooling or materials through RML.''<br />
<br />
== The Lathe ==<br />
Our Facilities page [[Facilities#Lathe|has]]:<br />
<blockquote><br />
'''Lathe'''<br />
[[File: Lathe2.jpg |200px|right | Lathe]]<br />
In the kitchen. <br />
<br />
Marked as a CJ18A Mini-Lathe from [[https://www.amadeal.co.uk/acatalog/CJ18A-Mini-Lathe-7x14-Machine-100mm-3jaw-Metric-With-Metal-Gears-AMA_LA_CJ18_M_3_MGRB.html Amadeal]]<br />
[[https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Manual]] <br />
<br />
[[Media:Lathe InductionNotes.pdf| Induction Document]]<br />
<br />
Possible upgrades:<br />
*https://www.youtube.com/watch?v=GwT-JQLbNPA<br />
<br />
''Please do not use the lathe until you have received induction'' <br />
<br clear=all><br />
</blockquote><br />
Its a Chinese import 7x14 mini-lathe. The 7x14 refers to the maximum diameter and length of work, in inches and is only a theoretical measure of the working envelope as you loose length to the chuck + any tailstock tooling, and the diameter is over the bed, not the cross-slide. See actual specifications below. <br />
<br />
Most if not all Chinese 7x10 to 7x16 mini-lathes seem to be remarkably similar (not uncommon with Chinese products due to [https://www.bunniestudios.com/blog/?p=284 Shanzhai (山寨)] )<br />
and the OEM of our Amadeal CJ18A Mini-Lathe was probably [https://www.made-in-china.com/showroom/cheap-lathe Yangzhou Realbull Machinery Co. Ltd]. Very similar lathes are also made by [https://www.siegind.com/lathe-machine.html Sieg], but their lathes tend to be slightly less sophisticated than the equivalent Realbull models.<br />
<br />
''N.B. Many Sieg parts are known to have slight but critical differences from Realbull parts, so '''DON'T''' order Sieg spares for a Realbull lathe!<br />
<br />
== Key Specifications ==<br />
Amadeal says the CJ18A Mini-Lathe is a 7x14 model with:<br />
<blockquote><br />
* Power 550 W<br />
* Distance between centres : 350 mm<br />
* Swing Over Bed: 180 mm<br />
* Swing Over Cross Slide: 110 mm<br />
* Taper: MT3<br />
* Tailstock Taper: MT2<br />
* Chuck diameter: 100 mm<br />
* Spindle Speed: 50 - 2500 rpm ''(with digital readout)''<br />
* Spindle Bore: 20 mm<br />
* Cross slide Travel: 65 mm<br />
* Range of Metric Threads: 0.5 - 2.5mm.<br />
</blockquote><br />
* The lead screw is metric, pitch 1.5 mm.<br />
* The spindle center is 90.6 mm above the flat of the bed (measured).<br />
<br />
Even though the compound and cross slide handwheels appear to be calibrated in thousandths of an inch, as ours is a metric machine, they only approximate that. One turn of a slide handwheel is 1mm advance, and they have 40 divisions, so each division is 0.025 mm, (approx. 0.984 [https://en.wikipedia.org/wiki/Thousandth_of_an_inch thou]). Similarly, the tailstock quill advances 1.25 mm per handwheel turn, which has 50 division dial, giving the same 0.025 mm divisions, but only 4 turns per 5 mm. The carriage handwheel is awkward - it moves approx. 19.2 mm per turn, and doesn't have a dial scale.<br />
<br />
== Notable Accessories ==<br />
We have:<br />
* [https://www.amadeal.co.uk/acatalog/160mm-Face-Plate-for-the-4-Mini-lathe-AMA_AC_CJ18A_FP160RB.html#SID=129 160 mm (6 1/4") Faceplate]<br />
* 100 mm (4") three jaw self-centering chuck (OEM standard) 22.5mm bore, with inside and outside jaw sets<br />
* 100 mm (4") four jaw (independent) chuck with reversible jaws (8 TPI screws)<br />
* Tailstock drill chuck (max. 13 mm dia.)<br />
* Live center for tailstock (+ OEM fixed center) <br />
* Four way Tool Post (OEM Standard)<br />
* [https://www.amadeal.co.uk/acatalog/Quick_Change_Tool_Post_for_the_mini-lathe.html Quick Change Tool Post] + 3 tool holders<br />
* [https://www.amadeal.co.uk/acatalog/Fixed-Steady-for-Mini-Lathes-AMA_AC_CJ18A_FSRB.html#SID=145 Fixed Steady Rest]<br />
* [https://www.amadeal.co.uk/acatalog/Travelling-Rest-for-Mini-Lathes-AMA_AC_CJ18_TSRB.html#SID=144 Travelling Steady Rest]<br />
<br />
''You'll find all of the above on the shelf above the lathe, with the accessories in the wooden box, apart from the steadies, which live next to it. Change gears, spare parts, and most cutting tool tips/blanks are in labelled white rectangular tins behind the lathe.''<br />
=== Measuring Tools ===<br />
We have:<br />
* Various dial indicators - the one with the adjustable magnetic base stand is the most convenient for most lathe setup work.<br />
* 25mm micrometer (in little grey case)<br />
* Grey case containing set of measurement tools including dial calipers, micrometer, steel rule (metric & inch), engineers square, and a fish-tail gauge<br />
<br />
''We currently lack''<br />
* ''A tool height setting gauge''<br />
<br />
=== Hand Tools ===<br />
Some common tools needed for normal use are kept with the lathe, in or attached to the wooden accessories box:<br />
* 2 mm Allen key - adjusting cross-slide and compound gibs<br />
* 4 mm Allen key - quick change toolholder tool clamping screws + height adjust, tightening dials<br />
* 5 mm Allen key - four way toolpost tool clamping screws, engaging/disengaging threading indicator<br />
* 6 mm Allen key - locking/unlocking quick change toolholder<br />
* 8 mm spanner - locking carriage when 8 mm socket can't be used, locking gib adjuster nuts <br />
* 13 mm spanner - changing chucks, locking steady rest jaws<br />
* Very long needle nose pliers - for grabbing swarf safely, holding one end of emery cloth safely so you can keep your fingers away from the jaws, and extricating small objects from awkward places.<br />
<br />
== Change Gears ==<br />
[[File:BC puller 1.jpg|thumb|Custom puller for B-C stub shaft]] [[File:BC puller 2.jpg|thumb|Pulling the B-C stub shaft]]<br />
See "Conquest Super Lathe" manual ([[#Manuals|below]]), section '''4.7 Change Gears''', PDF pages 28-29, but see below for mesh adjustment. The LittleMachineShop.com "Mini Lathe User’s Guide" (also below) section '''Threading''' gives a far better explanation, with pictures and diagrams, but its for a lathe with a US 1/16 inch pitch leadscrew, not a metric 1.5 mm pitch one like ours, so you *MUST* ignore all the tables in that section, replacing them with metric mini-lathe (with 1.5 mm pitch leadscrew) equivalents. <br />
<br />
We have the following tooth count gears: 20,20, 30, 35, 40,40, 45, 50,50, 60,60, 80,80<br />
which consist of the OEM power feed gears + the metric change gear set. Apart from the metal 20 tooth pinions, they are all plastic, probably Delrin if the molded in 'POM' marking can be trusted, but possibly plain Nylon 6, and are metric Module 1.<br />
<br />
If we wanted to add the capability to cut US/Imperial threads we'd need to buy additional 55, 57 and 65 tooth gears, and possibly a 21 tooth metal pinion.<br />
<br />
CGTK's [https://www.cgtk.co.uk/metalwork/calculators/changegears/minilathe?gears1=20,20,30,35,40,40,45&gears2=50,50,60,60,80,80&gears3= Change Gear Calculator] ''(link preloaded with our gear list)'' is useful if you don't want to calculate the ratios from first principles. Not all suggested combos will physically fit.<br />
<br />
* Take care *NOT* to loose the keys in the A and D shaft keyways - turn each shaft till the keyway is up before removing the gear. <br />
* The B and C gears are coupled by a hollow stub shaft (with an integral key), which is so tight in the gears it has to be pressed or driven out - I've made a puller just for this task, kept in the change gears tin.<br />
* The center of the B-C stub shaft *MUST* be lubricated where it runs on its pin on the change gear banjo bracket, with grease or heavy oil. ''Seizure of the stub shaft due to running dry is a frequent cause of catastrophic mini-lathe geartrain failures!''<br />
* Don't get oil on the change gears as it can cause plastic gears to crack. Only PTFE drylube or plastic compatible white grease should be used on their teeth. <br />
* Adjust the B-C pin position in the straight slot first to set the C to D gear mesh, tighten its nut, then swing the whole banjo about the D shaft boss to set the A to B mesh, and finally tighten the banjo clamping nut.<br />
* Check both gear meshes have running clearance by turning the chuck by hand enough to complete one full turn of the leadscrew, and by attempting to turn the intermediate gear(s) to assess backlash, If excessive resistance is felt or if there's significant backlash, readjust the gears. If you have difficulty judging the mesh, a strip of 80 gsm copier paper (approx. 0.1 mm thick) wound into the meshing teeth before tightening the stud or banjo will give appropriate clearance once removed. Once setup, check the gears run quietly under power.<br />
* If the sum of the tooth counts C+D is the same as for the ones you just removed and they were correctly meshed, you don't need to move the stub shaft pin. If A+B is <u>also</u> the same, you don't need to move the banjo. e.g. If it was set up for 16:1 reduction power feed, 1 mm (40:60 - 50:50) for M6 and 1.5 mm (e.g. 40:60:40) for M10 pitches can thus be achieved by only swapping gears. <br />
<br />
''The change gears, puller, etc. and a box spanner for the banjo nut are kept in a white rectangular tin behind the lathe.''<br />
<br />
=== Power Feed ===<br />
When used for turning with power feed, the change gears should be set for a 16:1 reduction (A:20 : B:80 - C:20 : D:80) using the pair of small metal 20 tooth pinions and the 80 tooth plastic gears (largest in set), for a feed of 0.09375 mm per turn (1.5 mm/16). Unless continuing your threading project the next session, please re-fit the 16:1 power feed set after threading so the power feed is ready for use. <br />
<br />
* *ALWAYS* leave the feed direction selector lever in its neutral (no feed) position, and the half-nuts open after use.<br />
* *ALWAYS* check the carriage lock is disengaged before engaging power feed. Unlock the carriage after use. <br />
<br />
=== Threading Dial ===<br />
The threading dial is an aid to re-engaging the half-nuts at the right moment so the tool will retrace its previous path cutting deeper, rather than offsetting axially some fraction of the thread pitch and ruining your work. Its based on the concept of the lowest integer multiples of the leadscrew and thread ''(being cut)'' pitches that exactly match, but for mechanical simplicity it only covers certain selected multiples of the leadscrew pitch.<br />
<br />
We have a choice of three pinion gears:<br />
{| class=wikitable<br />
|+ Threading dial Pinion Gears<br />
|-<br />
! Teeth !! Colour Dot !! Usable lines !! OD gear !! Dist. per turn<br />
|-<br />
| 14 || Red || 1,7 || 7.51 mm || 21 mm<br />
|-<br />
| 15 || Orange || 1,5,9 || 8.05 mm || 22.5 mm<br />
|-<br />
| 16 || Green || 1,4,7,10 || 8.37 mm || 24 mm (2 mm/div)<br />
|}<br />
They are now colour coded, with a paint dot on the gear end face ''(the only non-wear surface)''. The 16 tooth one is normally left on the lathe, but disengaged when not threading to minimise wear on the lead screw. The others are kept in the Change Gear tin.<br />
<br />
There's a threading dial 'pickup' calculator here: https://www.cgtk.co.uk/metalwork/calculators/threaddialindicator <br />
<br />
Initially select ''Lathe:'' '''Custom''', and enter the following below:<br />
* ''Units:'' '''Metric'''<br />
* ''Lead Screw Pitch (mm):'' '''1.5'''<br />
* ''Thread Dial Indicator Gear Teeth:'' '''16,15,14''' <br />
* ''Lines on Thread Dial Indicator:'' '''12''' <br />
* ''Line Marking:'' '''Every Line Numbered'''<br />
Note the teeth list is entered in reverse order so the resulting table highlights any required pinion changes.<br />
<br />
N.B. The dial is only friction clamped to the pinion by its center screw. If you have any reason to suspect it may not be properly aligned: <br />
# With the power off and the carriage unlocked, engage the feed direction lever upwards. You'll probably need to turn the chuck by hand to get it to engage.<br />
# If the threading indicator isn't already engaged, loosen the threading dial support block bolt, pivot the block to engage the pinion with the leadscrew and retighten the bolt.<br />
# Engage the half nuts, again turning the chuck by hand till they drop in. <br />
# Turn the chuck a couple of turns, top towards you to take up any backlash, then lock the carriage, taking care not to push it left while locking it.<br />
# Loosen the screw securing the dial to the pinion.<br />
# Align the '1' line of the dial with the index line, by rotating the dial clockwise, then retighten the screw.<br />
# Don't forget to disengage half-nuts and unlock the carriage!<br />
<br />
The above instructions should result in the half-nuts engaging cleanly when exactly on any valid line when threading towards the headstock. If it is required to thread away from the headstock, there will be a slight offset from the line due to backlash between the spindle gear and leadscrew, so engage slightly early.<br />
<br />
Changing the pinion:<br />
# Loosen the threading dial support block bolt and disengage from the leadscrew.<br />
# Undo dial center screw, and remove it and the dial, dropping the old pinion out the bottom.<br />
# Oil the shaft of the new pinion with a drop of light oil and insert it from below, gear end down.<br />
# Refit dial and screw.<br />
# Check the dial and pinion turn freely with minimal resistance.<br />
# Align as above.<br />
<br />
== Tailstock and Steadies ==<br />
These are mostly used to support long work ''(long with respect to its diameter)'' to improve rigidity, increasing accuracy and reducing chatter. The Tailstock quill is also used with a drill chuck for drilling.<br />
=== Tailstock ===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock base]]<br />
The tailstock can be offset to turn shallow tapers between centers. We don't currently have the accessories to turn between centers, namely <s>a MT3 dead center for the spindle, or</s> any drive dogs for the work. Also realigning the tailstock after turning a taper can be a PITA. The photo shows the tailstock adjusting screw locations ''(C - Lateral, and D - Skew)'' and the block on the baseplate they engage with. Adjustments can only take effect when the tailstock locking lever is eased to take the pressure off the baseplate. As we don't have a MT3 center, one has to turn a fresh point on a test workpiece for a rough tailstock alignment reference. Fine alignment, to avoid inadvertent taper turning, can be done by mounting a long precision ground bar between the chuck (or preferably a center in the spindle), and a dead center in the tailstock and sweeping it with a dial indicator on the carriage. Finally a test cut should be taken at either end of a bar between centers, and the diameters checked with a micrometer. Assuming the bed has previously been properly levelled and shimmed to take out twist ''(not the case at RML as we don't have it bolted down)'', any remaining difference in diameter will be double the tailstock offset, smaller at the tailstock being offset towards the front. Fine adjustment cant be achieved by jacking with the screws, its best to ease the adjusting screws, bump the tailstock into alignment then take up the screws again, checking the alignment is maintained when the tailstock is unlocked and relocked. There is no vertical adjustment, though shims can be added between the tailstock and its base.<br />
<br />
==== Tailstock Quill ====<br />
There is a metric/imperial scale on the top of the quill, read against the end of the tailstock, for depth measurement when drilling. The tailstock quill has a 1.25 mm pitch thread and a 50 division dial. Each division is therefore 0.025 mm, and it only takes 4 full turns of the handwheel to move the quill 5 mm. <br />
<br />
To eject MT2 taper tooling and centers from the tailstock, wind the quill all the way in.<br />
<br />
N.B. The quill anti-rotation pin (dog-tip setscrew + locking nut in top of tailstock near to the quill lock) is only M5. It will sheer if a large diameter drill jams in the work. Please back it out clear of its keyway if using large drills, and use alternative methods of preventing chuck rotation. To re-engage it, crank the quill out till you can see the keyway, align it with the screw and screw in the screw till it gently bottoms out, then back it off a quarter turn. Try twisting the quill to check its properly engaged, then tighten the locking nut gently to hold the screw in position clear of the bottom of the keyway.<br />
<br />
=== Steady Rests ===<br />
We have two, both with brass tips that must be kept lubricated during use.<br />
<br />
The fixed steady mounts on the ways, and is most useful when turning longer work that wont fit through the spindle bore. Adjustment is critical, and the surface the tips run on must be smooth and concentric, as any misalignment that forces the work off center will result in the work wobbling in the chuck, marring it, with a high risk of it becoming un-chucked, which can be dangerous at speed.<br />
<br />
The travelling steady mounts to the headstock side of the carriage to locally resist the deflection of thin long work, due to the cutting forces. It only has two tips, to resist climb, and deflection away from the tool, and requires readjustment after every cutting pass.<br />
<br />
== Tooling and Tool Holders ==<br />
'''Key dimensional data:'''<br />
* The quick change holders accept up to 10 mm shank tools. <br />
* The four way toolpost has 50 mm long sides, a seat width of 15 mm and can clamp tools of up to 5/8" (15.875 mm) shank ''(check this)'', but the slot base is only 10.4 mm below the spindle center so cannot be used with >10 mm shank tooling unless it has a dropped tip. Large tooling with a centered tip is also problematic as you run out of height above the shank when trying to shim to match the spindle center height. <br />
<br />
===Quick Change Toolpost===<br />
I've got the quick change toolpost and toolholders setup for mostly easy use. The three toolholders came with cantilever height setting arms which historically haven't been installed as the supplied fixing screws were too short. That's all now sorted out and a HSS RH turning tool and a HSS hand-ground grooving/parting-off tool are now mounted in two of the holders and set to height. The third is kept free for other tools. <br />
<br />
The quick change toolpost has been modified with a spring to press the dovetail clamp outwards and help stop it twisting or flopping about to ease toolholder fitting and removal. The dovetail clamp (socket headed screw on toolpost side opposite dovetail) feels a bit stiffer than before, but will take less than half a turn to go from open (with the toolholder lifting out or dropping in easily) to fully clamped. As there is so much less clearance in the open position you should no longer need to wiggle the toolholder while clamping it to get a consistent height. If the dovetail clamp ever gets misaligned, twist it straight by eye, slacken off a bit further than usual to get a toolholder on, clamp it to align the dovetail then release, reseat the toolholder and re-clamp to ensure its at its preset height. You cant adjust the height by 'jacking' with the height screw due to its offset leverage. Instead, back off the height screw and hold the toolholder at the desired height while locking the dovetail clamp, then adjust the height screw (and locking nut) to hold it there, then check it doesnt change height significantly when you unclamp and reclamp the dovetail. <br />
<br />
Unfortunately the OEM height setting screws foul the toolpost locking nut handle. Currently, if you need to swap toolposts you will have to first remove the quick-change tool holder from the post. There is enough nut handle swing to allow the quick change toolpost to be unclamped and rotated to fine set the tool angle without removing the toolholder. It also seems the mating surfaces may be slightly out of square, as if you rotate the toolpost 90° or 180°, the nut swing may be insufficient to re-clamp it without removing the toolholder to do so. Add a M10 washer under the locking nut if the handle ends up pointing in an undesirable direction! A thin M10 washer is kept with the toolpost collar for this purpose, and will shift the handle position by about a third of a turn. <br />
<br />
''ToDo: Make a taller nut of a similar pattern, to clear the height setting screws.''<br />
<br />
===Four Way Toolpost===<br />
The OEM four way toolpost is significantly more rigid than the quick change toolpost + holders because it has fewer and thicker parts and less overhang. Therefore the four way toolpost should be used when using carbide tooling. It requires shimming under the tool to set the tip height to the spindle center height - see below. The tool shanks are mostly significantly less than 15 mm wide, so need to be centered under its clamping screws, tempting as it is push the shank in for full side contact with the toolpost. If possible clamp the shank with all three screws not just two.<br />
<br />
==== Shimming ====<br />
We typically only mount up to two tools, and want maximum rigidity, so use 50 mm x 15 mm shims, (the full seat area), preferably with deburred edges and radiused corners so they aren't a hazard to the operator.<br />
<br />
We have pre-cut and marked shims of the following thicknesses: <br />
* 1x 3.23 mm, 2.42 mm, 1.56 mm, 0.32 mm, and 0.25 mm<br />
* 2x 1.00 mm, 0.77 mm, 0.12 mm, 0.11 mm, 0.10 mm and 0.05 mm<br />
* 4x 0.53 mm<br />
<br />
Our shims are mostly found materials (hence the awkward thicknesses) and are mostly a mixture of aluminium and steel, with a couple of GRP ones. The toolpost seat '''<u>must be absolutely clean</u>''' to avoid embedding debris in the aluminium or GRP shims, to get a consistent height and avoid tilting the tool - wipe it every time you change a tool! Put the thin shims at the bottom of the stack to avoid the tool shank edges creasing them. Shims are kept in a little yellow plastic box with a clear lid, near the carbide tools case.<br />
<br />
I made a tool height setting gauge (T shaped black acrylic with steps in its sides) which can be used to check the tool tip height matches the spindle center height using either the flat of the ways or the saddle as a reference. The tool tip should just fit under the lip of the appropriate step, with the T arms across the ways flats or on the saddle. It is kept in the box with the carbide insert tools.<br />
<br />
''ToDo:'' <br />
<br />
* ''Cut more shims neatly, mark them with their thickness.''<br />
* <s>''Do test cuts and start noting shim stack-ups for various tools.''</s><br />
* ''Organise shim storage!''<br />
<br />
=== HSS Tools ===<br />
[[File:Tool Bit Geometry.jpeg|thumb|Single point cutting tool geometry]]<br />
Our HSS tools are made from 8 mm square bar stock, hand-ground to tip profile in-house. See LittleMachineShop's [https://littlemachineshop.com/images/gallery/instructions/grindingtoolbits.pdf Grinding Tool Bits] notes. <br />
<br />
I've installed our usual HSS LH turning and parting off tools in two of the quick change holders and set the heights correctly. There are a couple of other HSS tools or tool blanks knocking about. Taking heavy cuts turning steel (even with good cutting oil) blunts HSS tools fairly quickly, which are time-consuming to re-sharpen nicely without a dedicated tool & cutter grinder with appropriate jigs. Its worth noting that the usual 'speeds & feeds' tables are commonly based on surface speeds expected to give a half hour (active cutting) tool life before resharpening.<br />
<br />
I touched up the LH turning tool by lapping on wet & dry (silicon carbide) paper on glass (Aka: [https://en.wikipedia.org/wiki/Scary_sharp 'Scary Sharp']) working upwards through the grits 200, 400, 600 and finally 1000, initially 'bluing' the surfaces to be lapped with a marker pen to see which areas needed taking down more. The end of the tool was significantly uneven so I touched that up freehand on the bench grinder to flatten it when it became apparent that 200 grit lapping wasn't cutting where it needed to. There was an existing micro-bevel on the leading side, which I kept. Finally I 'dubbed' the leading corner vertical edge on the 1000 grit to give it a very slight nose radius. A test cut on brass gave a very nice finish when turning.<br />
<br />
''Ian B has purchased some spare 8mm HSS tool blanks - talk to a lathe trainer if your proposed lathe work needs custom ground HSS tooling.'''<br />
<br />
=== Brazed Tungsten Carbide Tools ===<br />
Somewhat of a half-way house between hand ground HSS tooling and insert tooling with the disadvantages of both and some more besides - e.g. they are much harder to sharpen. So why do we bother? Some tool geometries would be awkward and tedious to hand grind, and Chinese import brazed carbide tooling is about half the price of similar HSS tooling, and far more readily available. Also, for space constrained tooling like boring bars, if you want carbide, for insert tooling, the size of the insert and its clamping seriously limits the minimum hole diameter you can work in. I have purchased a set of 3/8" shank brazed carbide tipped boring bars, but we currently cant sharpen them, due to lack of a diamond grinding wheel. <br />
<br />
=== Tungsten Carbide Insert Tools===<br />
Decoding ISO insert tooling part numbers: https://www.cutwel.co.uk/blog/learn-the-turning-tool-iso-code-system<br />
[[File:Carbide set.jpg|800px|thumb|left|Our set of Tungsten carbide insert lathe tools (before the new inserts were fitted)]]<br />
<br />
{| class=wikitable<br />
|+ Tools, left to right, (+ last across top):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| SSKCR0610H06 || 75° through boring || SCMT06204 || Long || 6 || 6.34 || ''4.33''<br />
|-<br />
| SSSCR0610H06 || 45° deep facing, internal chamfering || SCMT06204 || Long || 6 || 6.13 || ''4.58''<br />
|-<br />
| SWUCR0610H05 || 93° boring, deep facing || WCMT050308 || Long || 6 || 6.22 || ''4.48''<br />
|-<br />
| SWGCR0810E05 || 90° RH turning & facing || WCMT050308 || Short || 8 || 8.25 || '''2.45'''<br />
|-<br />
| SSSCR0610E06 || 45° turning, chamfering || SCMT06204 || Short || 8 || 8.75 || ''1.93''<br />
|-<br />
| SSBCR0610E06 || 75° RH turning, chamfering || SCMT06204 || Short || 8 || 8.72 || ''1.98''<br />
|-<br />
| LW0810R-04 || 60° external threading || JCL15-120 || Short || 8 || 7.44 * || ''3.28''<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || 8.23 || ''2.5 ?''<br />
|-<br />
| LN0813R-04 || 60° internal threading || JCL15-120 || Long || 7.95 || 7.44 * || ''3.28''<br />
|}<br />
<br />
{| class=wikitable<br />
|+ More Tools, (loose in tin):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || ~8.5 (not in use) ||<br />
|-<br />
| [https://www.glanze.co.uk/product/glanze-12-mm-60-degree-metric-internal-threading-tool/ Glanse SIR0012K11] || 60° internal threading bar || 11IRA60 || Long || 12 dia || ??? || ???<br />
|}<br />
''Shim stack heights in bold are tested, in italic are only calculated.'' ''Tip heights marked * are with new JCL15-120I inserts. The single remaining plain JCL15-120 insert has a slightly higher tip height.''<br />
<br />
Carbide tooling typically requires two to three times more speed than HSS and at least a couple of 'thou' depth of cut for best results.<br />
<br />
Chatter can rapidly kill carbide tooling by chipping the cutting edge. To improve rigidity and reduce the risk of chatter, the cross-slide and compound gib screws need to be well adjusted so there is minimal play in the slides, tool stick-out should be minimised, the four way toolpost should be kept over the cross-slide, and the work should be kept close to the chuck (or otherwise supported by tailstock or steady rest) to avoid excessive deflection.<br />
<br />
Thermal shock is almost instant death to carbide, and when dry cutting the insert tip can run very hot, so do not add extra cutting fluid manually during the cut. Pre-apply what you need, evenly, before starting the cut.<br />
<br />
Parting off or facing to center is high risk - if the tool tip is even slightly below center or if tool or work deflection takes it below center, the work will tend to climb over the tool tip as the cut approaches center, breaking the insert. To avoid this, the tool should be shimmed slightly above center, sufficient to allow for work and tool deflection, and unless very close to the chuck, a steady should be used. Its often preferable to part to a couple of mm dia. remaining then stop and saw through the remainder, then clean up by facing. Parting off hollow parts is much lower risk.<br />
<br />
Further investigation of the Tungsten carbide insert tool height situation is not encouraging - the so-called 'set' in question does not have a consistent tip height ''(see above table)''! In a real set, the insert seats *should* be machined allowing for the insert thickness to bring all the cutting edges to the same height with respect to the shank underside. However if you place them tip to tip on a table its easy to see there is considerable height variation, so they need to be individually shimmed (or at best, one machined shim will only be right for two or three tools). At this time we don't have dedicated shim stacks for each tool.<br />
<br />
A 2.42 mm thick shim brings the SWGCR0810E05 90° RH turning & facing tool almost exactly to center height, and good results were obtained turning 1" steel pipe. However facing 50mm steel bar stock to center found it to be slightly low, leaving a fractionally under 0.05 mm 'pip' so it needs another 0.03 mm to bring it fractionally above center. Fractionally too high is generally preferable to fractionally too low, due to tool deflection, so adding an 0.05 mm shim to the stack should produce optimum results.<br />
<br />
==== Inserts ====<br />
Ian B has purchased the spare inserts we needed in sets of five. He even was able to get the CK3 parting-off inserts which had been difficult to source!<br />
<br />
Inserts used in above tool set:<br />
* 3x SCMT06204 (square, indexable) https://www.rdgtools.co.uk/acatalog/SCMT-06-Carbide-Insert.html<br />
* 2x WCMT050308 (triangular, indexable) https://www.rdgtools.co.uk/acatalog/WCMT-05-T3-08-5XTIP-8813.html<br />
* 2x JCL15-120 (60 deg threading point) https://www.rdgtools.co.uk/acatalog/X5-JCL-15-120L-THREADING-TIPS-60-DEGREE--X5-TIP---23455.html<br />
* CK3 (parting off) https://www.rdgtools.co.uk/acatalog/CK3-CARBIDE-TIPS---PARTING--BOX-OF-5PCS--9437.html<br />
<br />
Inserts used in other tools:<br />
* 1x CK3 (as above) also missing from spare parting off tool<br />
* 1x 11IRA60 in Glanse threading bar + 1x spare<br />
<br />
=== Drills ===<br />
Various sizes of center drills are kept in a plastic bag next to the wooden accessories tray. There's also a small box of 2.5 mm center drills.<br />
<br />
We have a set of 11 TiN coated HSS drill bits from 1.5 to 8 mm, (in a cylindrical plastic index box) for tailstock drilling of brass, aluminium and non-abrasive plastics. To keep them sharp enough for the precision work we expect from the lathe, please don't use them for steel or reinforced plastics, and don't borrow them for non-lathe use. Metric and US [https://littlemachineshop.com/reference/numberdrillsize.php numbered]/[https://littlemachineshop.com/reference/letterdrillsize.php lettered] general use HSS drill bits are kept in two red metal index boxes next to the drill press.<br />
<br />
== Using the Lathe ==<br />
=== General ===<br />
Making dimensioned parts is primarily done by touching off the tool tip on a reference surface (with the lathe stopped, turning the chuck by hand), zeroing the handwheel dial, then manually counting turns and divisions. When backing off the tool its best to do so by exactly one whole turn so you don't forget the previous dial position. Stopping and measuring the work before taking the final cuts is essential if high accuracy is required. ''I've changed out the dial setscrews for flat tip ones with a tiny slug of solder under them so the dials are now friction fit on their shafts. i.e. if you hold the handle firmly taking up the backlash in the direction of cut, you can zero the dial just by grabbing and twisting it.''<br />
<br />
Carriage movement is less easy to measure as the handwheel is uncalibrated and advances an awkward bit over 19.2 mm per turn. Your options here when shoulders or other features must be exactly positioned are, in order of increasing accuracy: <br />
* Use measuring instruments, scribe the work at the desired length then work to the scribed line. Its often convenient to black the work with a permanent marker, then scribe with the tool tip, turning the chuck by hand.<br />
* for short distances, lock the carriage and use the compound, set parallel to the work<br />
* Set up a long travel dial indicator to measure carriage motion. <br />
N.B. with the leadscrew stopped, and the threading dial engaged, with its default 16 tooth gear, it will make one turn for every 24 mm of carriage movement (2 mm/div). This isn't accurate enough for positioning but is sufficient to check you aren't out by a whole mm or more.<br />
<br />
Do not allow any solvents to contact the chuck guard clear plastic as it will make the plastic brittle, or even craze it, and try to avoid melting it with the work light!<br />
<br />
===Speeds & Feeds===<br />
The surface speed of the tool relative to the work (or visa versa) is important, and best results will be achieved when it is in a tool type and material specific range. Because the surface speed is proportional to the diameter and the spindle RPM, it is usual to vary the spindle speed in inverse proportion to the diameter to get the surface speed in the desired range, and keep it there as the tool tip moves closer to the spindle axis. <br />
<br />
A cutting speed chart for HSS tooling, published by Model Engineer magazine can be found [https://www.model-engineer.co.uk/sites/7/documents/cutting%20speed%20chart.pdf [here<nowiki>]</nowiki>]. The second row is the target feed rate and the rest of the chart, apart from the diameter column is RPM.<br />
<br />
For carbide tooling cutting iron and steels, recommended speeds are generally three times higher than for HSS, but the CJ18A 2500 RPM max. spindle speed (in high gear) means you can only reach the optimum speed range for over 15 mm dia work. For small diameter work, HSS tooling may well be a better choice.<br />
<br />
An online metric speeds calculator is here: https://www.cgtk.co.uk/metalwork/calculators/cuttingspeeds <br />
<br />
How to do the maths to calculate speeds and feeds: https://www.cutwel.co.uk/blog/speeds-feeds-made-easy<br />
<br />
If you can hear the lathe 'sing' as it cuts, you are getting chatter, which invariably results in poor surface finish. Try decreasing (or possibly increasing) the spindle speed till the resonance stops. <br />
<br />
Once you have a wavy surface due to chatter, a light cut wont clean it up as the tool 'twangs' from peak to peak. You have to take a deep enough cut to get under it. For precision parts, its therefore desirable to take a trial finish cut while still 0.5 mm or so oversize, to give an opportunity to tweak the cut to get a good finish, check for taper, and that the part wont be undersize (on your test finish cut nominal diameter).<br />
<br />
=== Slide Locks ===<br />
* The carriage can be locked to the ways using the M5 hex screw through the top of the saddle to the left of the cross-slide. Double check the leadscrew is disengaged and the half-nuts open before locking it. Lock it when facing.<br />
* The cross slide can be locked by a M4 socket headed cap screw just in front of its middle gib screw. Locking the cross slide is helpful when turning very shallow conical features where the cross slide handle is in the way of the compound.<br />
* The compound slide can be locked by a M4 socket headed cap screw in line with the edge of the toolpost mount on the side with the gib adjustment screws. In normal use it should be kept backed off half a turn but it is desirable to tighten it for parting off operations to keep the resulting end faces flat.<br />
<br />
=== Compound ===<br />
The compound consists of a locking swivel and a top slide allowing cuts to be made at an angle to the axis e.g to produce bevelled or tapered features. There is a difference between US and UK usage, in the US a compound angle of 0° means the compound slide is parallel to the cross slide, but in the UK, 0° is parallel to the ways. The compound angle indicator on the CJ18A follows UK practice, 0° parallel to the ways, but it is not to be trusted, its out by a few degrees!<br />
<br />
One of the deficiencies of the CJ18A lathe is the difficulty of setting the compound angle. It is held and locked by two screws hidden under the top half of the compound slide, which must be wound back till its toolpost end is clear of the pivot point to access them. This may have to be repeated several times to snug them up enough to tap it to the desired angle, then finally tighten them. <br />
<br />
We generally keep the compound slide set approximately parallel to the ways so it can be used for short-distance longitudinal positioning without measuring. However it is unlikely to be closely parallel unless a test bar has been swept with a dial indicator on the slide, or test cuts made on a large OD workpiece and checked for taper.<br />
<br />
=== Chucks and Chuck Jaws ===<br />
==== Terminology ====<br />
* Inside jaws have steps on the outside to grip the ID of hollow work, but can also be used as outside jaws on small diameter parts (i.e. that fit through the spindle). <br />
* Outside jaws have steps on the inside to grip the OD of the work.<br />
* Universal chucks have a scroll plate with a spiral screw thread that moves all the jaws.<br />
* Independent chucks have individual adjusting screws for each jaw.<br />
<br />
==== The Chucks ====<br />
* The three jaw universal chuck can only grip near round or hexagonal work, which it centers, but its concentricity is not perfect so e.g. if you reverse the work and continue turning at the same diameter from the other end, you will see a line where the turned surfaces meet. It has separate sets of inside and outside jaws, and we normally keep the inside set installed to use as outside jaws for small diameter work.<br />
<br />
** Our jaws are individually numbered, stamped in the groove. They must be fitted in the correct sequence. The jaw slots are not clearly marked. Lowest runout for small dia. parts is achieved if you fit the jaws with #1 anticlockwise of the makers mark, then continue anticlockwise for #2 and #3.<br />
** A large strong rubber band is a great help getting all the jaws started on the scroll together - with slots #1 and #3 above the centerline and the scroll thread outer tip between #1 and #3, insert jaws #1 and #2 and put the rubber band round them to keep them in their slots. Insert jaw #3 and stretch the rubber band over it to hold it up into its slot. If the scroll was positioned correctly, all jaws should be at the same initial radius. The jaws can now be cranked in with the chuck key and they should all engage in step so they meet in the middle.<br />
:: ''Mini-lathe.com have the best instructions for [https://www.mini-lathe.com/mini_lathe/chucks/chucks.htm#Installing_Chuck_Jaws changing the jaws].'' <br />
<br />
* The four independent jaw chuck can grip most roundish or squarish work, which can either be carefully centered by the user, or deliberately gripped off-center. <br />
** Its jaws are reversible so can be swapped from inside to outside by simply cranking each jaw out and reinserting it the other way round, one at a time. DON'T move the jaws to different slots as they are likely to bind.<br />
** When setting up to face the sides of rectangular objects held crossways, it may be helpful to use both inside and outside jaw orientations, in symmetrical opposing pairs.<br />
** Its screws move their jaw 1/8" (3.125 mm) per turn<br />
<br />
* The jaws must '''never''' protrude from the chuck OD by more than one step, and for safety, its preferable they don't protrude at all, as they make the gap between the front of the bed and the chuck body an even more unforgiving meat grinder, and as the number of teeth engaged with the scroll or screw decreases, they loose strength, just when you need it the most to grip larger/heavier work. <br />
<br />
''Neither chuck is well suited to gripping tapered work safely. When seating work that doesn't quite fit through the chuck bore (which is larger than the 20mm spindle bore limit), be careful that it isn't seating on the chamfered edge of the chuck bore as it is far to easy to get the work slightly cocked so it doesn't run true.''<br />
<br />
==== Changing Chucks ====<br />
* When changing chucks, use the small grey plastic mat to protect the ways under the jaws in case you drop the chuck.<br />
* The spindle nose has two patterns of holes - the three hole pattern is for the three jaw chuck and the faceplate, and the four hole pattern is for the four jaw chuck. One hole is shared between the patterns, and is marked on the spindle nose.<br />
* To fit a chuck:<br />
** First check that the spindle nose and chuck back and recess are free of swarf, grit or other debris. Any foreign objects will tilt the chuck causing excessive runout and may mar the surfaces.<br />
** Remove the nuts and split lock washers from its studs, line its studs up with the hole pattern (preferably with the stud nearest anticlockwise to the makers mark through the marked spindle hole), fit and hold it in place with your right hand, and with your left, get the lock washer and nut on the top stud, and take up the slack.<br />
** One one nut is on, you no longer have to worry about dropping it, and can work round fitting the remaining washers and nuts, taking up the slack on each as you fit it. <br />
** Next, work round again getting them all finger tight, then tighten them gently, and finally work round fully tightening them. <br />
* Removal is the reverse of refitting. Put the washers and nuts back on the chuck's studs so they don't get lost.<br />
<br />
==== Gripping Threaded Work ====<br />
It is generally undesirable to chuck work gripped on a screw thread, as it is difficult to hold the work securely and get good concentricity while avoiding crushing the thread crests. However, if one must, one of the better ways of doing so is to wind a wire helix to fit the thread then clamp on the outside of the wire so it seats on the flanks of the thread. The wire should be mild steel or soft iron for steel parts and copper for aluminium and brass parts, single strand, round and of uniform diameter a little less than the thread pitch. It can be wound on the lathe, in reverse, by chucking a sacrificial mandrel of the same diameter and thread pitch, hooking the end of the wire round or under the jaw, against the direction of rotation, then holding the other end of the wire under tension with pliers and starting the lathe dead slow. Once wound and removed from the mandrel, the ends must be trimmed then it should be screwed on to the threaded work to provide a surface to chuck on.<br />
<br />
=== Faceplate Work ===<br />
Faceplate work is probably the most dangerous operation you can (or rather should) perform on a lathe. The working area is a large diameter spinning surface with protruding clamps to fixture the part that it is impractical to guard. Protruding clamps, studs, nuts etc. are very difficult to see at speed.<br />
<br />
'''Treat the faceplate with great respect and caution if you wish to continue to be able to count to ten on your fingers!''' <br />
<br />
The 65 mm cross-slide travel vs the 80 mm faceplate radius is a serious limitation that may require creative compound, toolpost and tool setups for larger parts, and doing full face cuts in two sections.<br />
<br />
''It is common practice to skim the faceplate to ensure it runs true. We have not (yet) done this, and wont till the spindle is in better bearings and the nose reground to minimise runout.''<br />
<br />
==== Clamping ====<br />
Open ended/sided clamps should be oriented so that cutting forces drive the work towards the clamping bolt/stud, not out from under the clamp. Minimize the protruding length of thread past the clamping nut, if necessary using sacrificial bolts or studs you can cut to length, or even using a long M8 stud for one of the faceplate mountings, so you can get a clamp nearer to the faceplate center. Double-check all clamps are secure, manually turn the faceplate to check the work and clamps clear the ways, top-slide and toolpost, and stand out of the 'line of fire' (a disc extending from the faceplate) when spinning up the work for the first time. <br />
<br />
If you need to machine close to a clamp, consider marking a safe limit circle on the faceplate and work with a marker pen to make it easier to see how close the cutting tool is to crash disaster. <br />
<br />
I strongly advise reading chapter two of Tubal Cain's book "Workholding in the Lathe" several times before your first faceplate setup, and if possible get another experienced lathe user to check your first few setups before spinning them up.<br />
<br />
==== Chuck Guard Removal ====<br />
The faceplate is too large diameter to fit under the chuck guard, but the guard has an interlock switch wqhich must be closed for the lathe to run. The guard is now fitted with wing nuts so it can be removed allowing the the interlock switch to close when using the faceplate. It *SHOULD* *ALWAYS* be refitted if a chuck is fitted, except when turning work too large to clear the guard. <br />
<br />
''The chuck guard is primarily there to make it very difficult to start the lathe without removing the chuck key and to reduce the area of large diameter spinning surface exposed. It may slow down the projectile if a chuck sheds a jaw but is unlikely to stop it. Also it serves to contain coolant spray spun off the chuck. As we don't use flood coolant this usually isn't an issue for us. As setting up for faceplate work doesn't use a chuck key, and the most hazardous zone is the face of the faceplate, with its spinning projecting clamps, with full access required for machining operations, which a guard would not cover, the consensus is that removing the guard is an acceptable risk.''<br />
<br />
=== Turning and Facing ===<br />
We are getting good results in aluminium, brass, and even steel using HSS cutting tools in quick-change tool holders, and the ~ 94 um/turn power feed. Unfortunately due to lack of rigidity in both the machine and smaller diameter parts, if you don't want the outer end to be over diameter, a light final cut and multiple 'spring' passes will probably be required.<br />
<br />
For aluminium, a sharp HSS tool and 0.5 mm (20 div) depth of cut gives good results with power feed for rapid stock removal. Its also easy maths as each cut takes ~ 1 mm off the diameter. Finish cuts should be much finer, 0.1 mm (4 div) is 'in the ballpark'.<br />
<br />
For steel, using carbide insert tooling, a 0.25 mm (10 div) depth of cut is more appropriate, and with pre-applied cutting oil, gives reasonable results with power feed if you use enough speed. The maths is not quite so easy as you are only taking 0.5 mm off the diameter per pass. Again, use finer finish cuts but try to plan your cuts so the final cut is still cutting, not smearing the surface!<br />
<br />
When facing or parting off, some skill is required to turn the cross-slide handwheel steadily to get a decent finish and to avoid shock-loading the tool tip. Increasing the spindle speed in one or more steps to keep up with the reducing diameter is advisable, but avoid speeds that cause resonances (resulting in chatter). When parting off, small through-hole parts may be caught on a thin rod chucked in the tailstock, and pre-positioned inside the work with its tip right up to the parting off position.<br />
<br />
==== Using the Steady Rests ====<br />
For the fixed steady rest, see Blondihacks' Lathe Skills #26 - How To Use a Steady Rest! [[#Youtube_Playlists_&_Videos|{below}]]<br />
<br />
Ours doesn't have ball bearing fingers, so a smooth surface on the work and adequate lubrication are essential. The thumbscrews can only tighten the fingers, so for small adjustments outwards you need to either slack off the clamping nuts or ease them slightly and use a drift against the back of the finger's slot. Once set, check the chuck still turns freely.<br />
<br />
The traveling steady rest needs to run on a machined surface, so at least for the first pass, must follow the tool, so its difficult to avoid using more compound slide overhang than is desirable. An initial surface should be cut next to the chuck or tailstock center before fitting the steady rest.<br />
<br />
Both are a PITA to fit - the fixed one has to have its clamping post inserted up through the bed, and the supplied spanner is useless near the headstock, and the travelling one's mounting holes on the saddle almost invariably need swarf picked out of them.<br />
<br />
==== Turning Between Centers ====<br />
<s>Using a MT3 to MT2 reducing sleeve, the MT2 dead center can be fitted in the spindle.</s> ''Currently the MT3 spindle taper is compromised.'' Alternatively, a soft center can be turned immediately before use in the three jaw chuck, but that must have its 60° point re-cut to concentric if the chuck is disturbed, and needs to be either large enough to bear on the chuck body, or must have a lip to bear on the end face of the jaws to take the axial thrust. Recutting the center is a PITA, as the compound angle must be set to 30° anticlockwise, then reset to a true 0° afterwards. Maybe a right-hand 30° end angle zero rake form tool is the answer, or use the carbide insert tool SSKCR0610H06 as a form tool with the toolpost rotated 15° anticlockwise.<br />
<br />
With the MT2 live center in the tailstock quill, this gives us a center either end of the work to hold it.<br />
<br />
We also need a drive dog similar to [https://littlemachineshop.com/products/product_view.php?ProductID=4473&category=1 this], and the corresponding drive post to bolt to the spindle nose. I have some 25mm bore thick wall iron pipe, which should do nicely. Lengths of the dog's straight tail and of the post TBD after I check how much the center protrudes. N.B. its recommended to tie the tail to the post to keep them in contact so they don't slam. ''Currently we will need to drive from the chuck jaws. Possibly use the exterior jaws with a short soft center gripped on the inside end and drive from the highest step.''<br />
<br />
=== Drilling ===<br />
Always start with a center drill so deflection of longer bits doesn't start the hole off-center. For larger bits (> 5 mm), first drill to the web size, then to final diameter. For a precision hole, drill slightly undersize and ream to final diameter. ''Supply your own reamers!''<br />
<br />
Caution: See note about the quill anti-rotation pin in section [[#Tailstock Quill|Tailstock Quill]] above.<br />
<br />
=== Boring ===<br />
Caution: As the spindle doesn't extend right through the headstock housing, if boring in a through hole, chips tend to fall out the back and tumble in the spindle bore till they fall into the change gears. To avoid this, one should plug the spindle bore with a wad of paper towel or rag and when cleaning up afterwards, use a rod to push it through towards the tailstock, with the chuck jaws (if fitted) wound clear of the spindle bore.<br />
<br />
A swivel bladed hole deburring tool (pale blue handle) can be found in the main room on the windowsill behind the drill press.<br />
<br />
A couple of boring jobs have been bodged with an awkwardly angled turning tool and achieving acceptable effective rake with enough clearance to reach deep enough into the hole has been problematic. I reviewed the tools we had and found none suitable for starting out in a 13mm bore, the max diameter we can (easily) drill. I therefore decided to buy a set of boring bars and make a holder for them. I had difficulty finding anything affordable under 10mm shank - the best low cost option was a [https://www.amazon.co.uk/dp/B07P5LGVBX set of nine 3/8" (9.525 mm) shank brazed carbide tipped boring bars], which would be close to the max capacity of the quick change boring bar holder - if we had one! Unfortunately this holder for our specific toolpost is difficult to find except in a toolpost bundle. Another annoyance is the variable tip height of the set, varying from 1.8 mm to 2.8 mm above the center of the shank.<br />
<br />
I therefore decided to make a boring bar holder of the [https://littlemachineshop.com/products/product_view.php?ProductID=1700 Littlemachineshop.com (USA) style] for use in the four way toolpost, as the additional rigidity will certainly help. Starting with a slightly over 50 mm length of 16 mm aluminium square bar and using the four jaw chuck , both ends were faced and an attempt was made to find its center and center drill it. It was then drilled out to ~9.8 mm after much drama due to blunt drills and drills that cut ~1mm oversize. Too big, but beggars cant be choosers as we didn't have a boring bar holder or a 3/8" reamer. Unfortunately the final hole ended up significantly off center. It was then chucked crossways and ~1 mm skimmed off its thickest side to gain clearance to allow it to be shimmed to height, then one side was slit lengthwise manually with a hacksaw.<br />
<br />
It was fitted to the for way toolpost and loaded with a booring bar, which clamped firmly. A 0.86 mm shim stack brought the tip of the largest boring bar almost spot on center height, with the difference easily accommodated by twisting the tool slightly. The three jaw chuck was then remounted, and a piece of iron pipe chucked for a test. It cuts well and leaves a decent surface finish.<br />
<br />
''The boring bar setup is a work in progress - talk to me before attempting to use them if you have a project that would benefit from boring..''<br />
<br />
ToDo: get something that can sharpen tools tipped with this grade of carbide - it needs some sort of diamond (or possibly CBN) wheel as green grit silicon carbide does little more than polish it. ''N.B. diamond wheels are rapidly eroded by grinding steel, so the supporting steel seat must be undercut with a regular grinding wheel before the diamond wheel can contact it.'' <br />
<br />
We'll also need 50 mm square sheet shims to fit under the toolpost to gain clearance in the toolpost above the tool or toolholder. A 2.4 mm shim would give us about the same above and below spindle center height, and we probably need a small selection of thinner ones.<br />
<br />
=== Thread Cutting ===<br />
The objective is to cut a thread that complies with the ISO metric thread profile. Our lathe is not currently equipped to cut non-metric threads, (with the exception of BA which have pitches based on metric threads of that era).<br />
<br />
[[File:ISO and UTS Thread Dimensions.svg|frame|center|Metric Thread Profile - from the geometry, H is ~86.6% of P]]<br />
<br />
Metric thread data - See 'Preferred Sizes' at: https://en.wikipedia.org/wiki/ISO_metric_screw_thread<br />
<br />
See "Mini Lathe User’s Guide" section '''Threading''' for general techniques *ONLY*, and above for change gears and threading dial setup.<br />
<br />
Amadeal specify the max. thread pitch as 2.5 mm. Any thread pitch greater than 1.5 nn requires the change gears to gear up. When gearing up it is desirable to distribute the ratio as evenly as possible over the two pairs of gears in the geartrain to avoid excessive tooth loading.<br />
<br />
==== External Threading ====<br />
Initially turn work to required Major Diameter, set up change gears and threading tool, touch off on the work, zero the top and cross slide dials, and do a 'scratch' pass to check the pitch. Back off the tool, return the carriage, and re-engage the half nuts on a valid dial line clear of the end of the thread then immediately stop the lathe, and hand turn the chuck till the tool tip is (hopefully) over the scratch to check the thread pickup. If all is good, return the carriage again, restart the lathe and start cutting your thread. <br />
<br />
Methods of doing so vary depending on the size of the thread and toughness of the metal, but straight-in plunge cutting is generally to be avoided as has the highest cutting forces, and does not reliably keep the carriage (and top-slide if set parallel to the work) loaded to avoid pitch errors due to backlash. <br />
<br />
If leaving the half-nuts engaged and reversing the lathe to return to the start of the thread for the next pass, its absolutely essential to back the tool out of the thread for the return pass as it will not follow the path of the cutting pass due to backlash in the geartrain, leadscrew mounts and half-nuts.<br />
<br />
==== Internal Threading ====<br />
''<nothing here yet>''<br />
<br />
== Cutting fluids ==<br />
=== Why bother? ===<br />
[https://youtu.be/mRuSYQ5Npek Watch this video] and contemplate what's actually happening to that thin ribbon of metal being removed. Most of the lathe's motor power is being turned into heat by internal friction in the chip being removed in the zone around the cutting edge, and surface friction at, and immediately behind the cutting edge, near-instantly heating the chip by up to several hundred degrees. Reducing the surface friction using a suitable cutting oil reduces the strain on the machine as a whole, and reduces workpiece and tool heating (and thus expansion) with consequent improvements in maximum usable feed and depth of cut, surface finish and accuracy. It also drastically increases the life of the cutting edge.<br />
<br />
=== Practicalities === <br />
We don't have a coolant system for the lathe and *really* don't want the maintenance hassles of using soluble cutting oil/coolant as if used infrequently its a PITA to keep recirculated high water content cutting fluids from going rancid and stinky, and they can also rust the ways, so even a total loss gravity feed system is problematic. Therefore if dry machining doesn't give a good enough finish, we tend to use oil applied topically, by hand to the work. <br />
<br />
* Hard brass is typically free-turning without oil, however some light oil for the final cut can improve surface finish, but with the disadvantage that it will increase loose chip buildup on the tool as hard brass typically forms short spalls or splinters rather than curly chips.<br />
<br />
* Many Aluminium alloys tend to be gummy, and Paraffin or other mineral spirits mixed with a little oil can help prevent the aluminum welding to the tool edge. WD40 will do at a pinch, but its messy to apply from a spray can.<br />
<br />
* Steel really needs *GOOD* cutting oil. Lard oil is the traditional choice for steel. If there are any objections to lard oil, we should bite the bullet and get some commercial dark high Sulphur cutting oil, but beware, many such oils use an additive package that includes lard oil.<br />
* Cast iron (except ductile) should be cut dry, as the carbon micro-inclusions self-lubricate it, and the carbide in the dust (primarily Cementite) are very abrasive, so tend to form a grinding compound if mixed with oil. <br />
<br />
I've sorted out an oil pot lid with a 1/2" brass collar soldered in to give a nice smooth sided hole, for ease of use and to minimize the risk of spills when using a brush to apply cutting oils, and got some dirt-cheap brushes. It fits Shippam's paste (and similar own-brand spread) jars and I've found several jars and ordinary lids to seal them for storage. Unfortunately it isn't the easiest to get this type of jars' lids back on square so they seal properly, and if you over-tighten them and there's a temperature change, they can be a total <expletive> to reopen. Using the rubberised handles of a large pair of pliers to grip the jar lid just above its rim is the best option, and avoids damaging the lids.<br />
<br />
''N.B. For the smaller brushes, the glue holding the bristles in is attacked by paraffin. To prevent loss of bristles, crimp the aluminium ferrule of each new brush of this type before use.''<br />
<br />
We have, in labelled jars:<br />
<br />
* Sulphurised Lard oil thinned with paraffin. Best choice for heavy cuts and threading in steel but stinky.<br />
* Lard oil thinned with paraffin. Good for steel and acceptable for softer copper alloys<br />
* Paraffin with a trace of light oil. Good for aluminium, and can help prevent squealing chatter on finish cuts in brass.<br />
<br />
I've also got some paraffin wax (in the form of a stubby candle), which can be applied lightly (under power) to brass and aluminium stock especially on the finish pass. It makes less mess than oil but unfortunately tends to build up on the tool tip, making it difficult to 'work by eye' without frequent pauses to clean the tool tip.<br />
<br />
We've also got a tin of [https://www.rocol.com/products/rtd-compound Rocol RTD cutting compound], which is a thick paste. Its highly recommended for drilling and tapping steel (in the drill press or by hand), but as a paste, is less useful for general lathe work unless thinned to a fluid consistency, e.g. with paraffin or white spirits. OTOH its certainly worth trying for high speed facing steel as it is less likely to get flung off.<br />
<br />
== Cleaning and Maintenance ==<br />
Swarf is a significant cut hazard to the operator, especially stringy swarf from cutting steel. Never touch it bare-handed - always use a tool e.g. a brush, or a hook, or needle nose pliers for grabbing long swarf.<br />
<br />
* After use, brush all swarf off the toolholder, compound and cross slide etc. ways and leadscrew. Ian B has blocked off the opening at the headstock end of the rear splashguard (to try to keep swarf out of the motor), so one must sweep the swarf towards the open tailstock end and catch it in a dustpan or similar. Preferably, also thoroughly clean out the chip tray under the lathe, but at least sweep out visible swarf.<br />
* Wipe up any cutting fluid residue and re-lubricate affected sliding surfaces with way oil.<br />
* Do not solvent clean the chuck guard, as it will make the plastic brittle, or even craze it. Water with a little detergent is permissible for cleaning it, with the guard totally removed from the lathe.<br />
<br />
Before engaging the half-nuts for power feed/threading, check the leadscrew is clean! ''Best cleaned under power, with a toothbrush.'' <br />
<br />
'''Caution:''' The traverse gears behind the carriage handwheel are in an open-backed housing and tend to become packed with swarf! Swarf buildup here will result in jerky carriage movement. Clean out as much as you can with a toothbrush ...<br />
<br />
===Lack of lubrication and/or swarf or dirt build-up can be disastrous===<br />
* If using the change gears/power feed, lack of lubrication of the B-C stub shaft center pin or either leadscrew end bearing can result in seizure and immediate destruction of one or more gears in the gear train or worse. <br />
* Small pieces of swarf can get between the saddle and ways, or into the slides degrading accuracy, possibly permanently if hard swarf scores them, or jamming them. The carriage handwheel gears behind the apron are notorious for accumulating swarf, and swarf buildup on the leadscrew can prevent the half-nuts engaging properly, resulting in scrapped work, and possibly stripped half-nuts. <br />
* Metal swarf can get into the motor (''though Ian B has modified the rear chip catcher to reduce the risk)'' or into the control box via the leadscrew, and short-circuit stuff. At best it will blow the fuse and need a strip-down to clean it out, at worst it may require a replacement [https://www.amadeal.co.uk/acatalog/Speed-Control-Circuit-Board--12amp-AMA_SP_CJ18_SCB12.html#SID=12 speed controller] ''(currently £96)'' and/or [https://www.amadeal.co.uk/acatalog/550W-motor-for-CJ18A-Mini-Lathe-467.html#SID=240 motor] ''(currently £105)'' and possibly other electrical parts. We should probably fit a [https://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C3-Mini-Lathe-Spares/C3-256-Leadscrew-Grommet-Dustproof-Cover C3-256 Leadscrew Grommet] to keep swarf out of the control box, as it tends to drop onto the 'Filter' board which is mounted horizontally, below the leadscrew.<br />
* Grit from grinding, sanding etc. forms a grinding paste with the way oil, and will rapidly wear out the ways, saddle and slides. Keep grit off at all costs e.g. by covering the ways and slides during grinding/sanding operations, and if there's any chance grit has gotten where it shouldn't, clean and re-lubricate *BEFORE* moving the carriage or slides, then move the carriage and slides, wipe down where they were with a clean paper towel and check there's no remaining traces of dirt other than clean way oil on the paper towel. If it doesn't come clean when you re-lubricate and move it again, a full strip down may be required to solvent clean and relubricate the precision sliding surfaces.<br />
* Although a metalworking lathe *can* be used to turn hardwood, wood dust and small chips are extremely pernicious, as they get everywhere, even clinging to clean surfaces, are abrasive due to their silica content, and are hygroscopic, promoting rust. An even more thorough clean-up than after using abrasives is needed, immediately afterwards. Oily wood dust and fine wood chips in significant quantities are a fire hazard, even in the trash bin.<br />
<br />
===Lubrication===<br />
See section: "Lubrication" in LittleMachineShop.com "Mini Lathe User’s Guide" [[Ian_M's_Lathe_Notes#Manuals|(below)]]. As we usually only open two nights a week, in the table on page 16, Daily lubrication becomes Weekly and Weekly becomes Monthly.<br />
<br />
===General Maintenance===<br />
* The grubscrews holding the cross-slide and compound slide dials tend to loosen due to vibration and use of the dials. Keep them snugged up, but not so tight the dials cant be set without an Allen key.<br />
<br />
* The screws holding the cross-slide nut tend to work loose due to vibration. Crank the handle to and fro through the backlash and visually check there is no movement of the screw heads in their holes. If there is, see the [[#Excessive_cross-slide_backlash|notes below]].<br />
<br />
===Removing the Carriage===<br />
Its possible to remove the carriage from the bed for cleaning etc. without dismantling it. The only stop to its motion is the righthand leadscrew bearing.<br />
<br />
Start by removing the tailstock. Crank the carriage to the tailstock end then remove the leadscrew bearing (two screws and a nyloc nut on the leadscrew end). With the half-nuts open, hold the leadscrew centered in them and crank the carriage off the end of its rack, then slide it off the end of the bed.<br />
<br />
Refitting is the reverse of removal, except (if its gibs are correctly adjusted) the carriage will be very tight on the end of the bed ways so may be difficult to work onto the ways without a stack of blocks of wood or similar to support it at exactly the right height. The righthand leadscrew bearing must be refitted with the carriage as close as possible to it and the half-nuts firmly closed to support the leadscrew at the correct height to hold it in alignment while the screws are being tightened. The nyloc nut controls leadscrew end-play. Fully tighten it then back it off slightly till the leadscrew turns freely with its change gear removed.<br />
<br />
If the Apron has been off, refit it with the screws no more than lightly finger tight and only finally tighten them after checking lead screw engagement at both ends of the carriage travel and that the rack and pinion operates smoothly over the full travel.<br />
<br />
== Issues and Annoyances ==<br />
As of September 2023 - mostly resolved, apart from the spindle bearings and runout, the lathe is in better condition than it has been for a number of years.<br />
<br />
===Four Jaw Chuck has two jaws too tight===<br />
Fixed 27/10/2023: Two of the chuck jaws were tight in their slots, making precise adjustment difficult due to lack of 'feel'. Moving the jaws round the slots showed the problem mostly followed the jaw not the slot. The grooves in the opposite sides of the affected jaws that run in the chuck slots were slightly out of true, and the rails either side of the slots were slightly too thick towards the center. Due to the difficulty of seeing the high spots, after cleaning up and deburring the jaws didn't do enough to ease them, I decided to grind the top of the rails where they were binding. Several repetitions of spotting with Engineer's blue, grinding, then diamond filing the high spots has eased them enough. I cleaned everything, greased the jaw slides and screws, and refitted the studs so the chuck is now fit for service.<br />
<br />
''N.B. Don't move the jaws to a different slot - the formerly tight jaws *must* stay in the slots furthest from the makers mark.''<br />
<br />
===Excessive Runout===<br />
Mostly fixed 24/10/2022: I ground the chuck seating surface of the spindle nose (outside lip) to under half a thou runout. This also cleaned up several burrs. It would be possible to do better, but that would need good spindle bearings, and a more rigid toolpost grinder mount.<br />
<br />
Our spindle nose was damaged years ago by a person with little mechanical aptitude (who shall remain nameless) beating it up with a hammer mushrooming the spindle nose. We are getting several thousandths runout at the end of the MT3 bore, a MT3 to MT2 reducer sleeve in it runs visibly out of true, as does the spindle nose flange. When you put a chuck on it, the runout is magnified by the distance from the spindle nose. Ideally we would replace the spindle when we change the bearings but its £52 [https://www.amadeal.co.uk/acatalog/4-Spindle-Upgrade-Real-Bull-Mini-lathe-CJ18-series-AMA_SP_CJ18_003RB.html#SID=9 from Amadeal] and money is tight. It may well require more work after the bearing upgrade. Once good bearings are in, if we can borrow a decent MT3 arbour as a reference, we should consider skimming the bore.<br />
<br />
===Spindle bearings===<br />
* The spindle bearings appear to be close to worn out. They are notably noisy when running, and there appears to be more slop in the spindle than is desirable. There is notable resonance around 600 RPM, and surface finish of end faces is often poor. We have some ideas for possible replacement/upgrade, but it requires a major teardown.<br />
<br />
: The original bearings are allegedly 6206-2RS or 6206-ZZ deep groove ball bearings - 2RS codes rubber seals both sides and ZZ codes metal shields. Although the deep groove gives reasonable ability to withstand axial loads, the bearing balls point contact means they are vulnerable to [https://en.wikipedia.org/wiki/Brinelling brinelling] due to shock loading. The jammed on three jaw chuck didn't help this, as before we skimmed the spindle nose lip, it had to be driven off using a bar through the spindle bore, shock loading the bearings every time. Also even a minor 'crash' could have brinelled them due to eccentric shock loading, and the lathe has previously been crashed badly enough to need drive gear replacement. There are also issues with the 'approved' method of spindle and bearing removal from the headstock brinelling them, even if you don't abuse the spindle nose with a hammer!<br />
<br />
: A possible replacement is 30206 tapered roller bearings. The new bearings are slightly thicker so the plastic spindle spacer (15) needs to be machined to length to get the 45 tooth spur gear that drives the change gears laterally aligned with the tumbler gears. If a temporary replacement (3D printed?) is fitted, the lathe can be run (without power feed capability) so this can be done on the lathe after fitting the new bearings. As tapered roller bearings have line contact, they are significantly more resistant to brinelling.<br />
<br />
: ''See [[Talk:Ian_M%27s_Lathe_Notes]] for notes, links etc. for this upgrade.''<br />
<br />
===Motor stuttering===<br />
* Fixed 21/09/2023: The motor was running very erratically and it was very difficult to set a speed. Several loose connections were found in the control box, mostly loose female spades to the motor controller board, but also a dry jointed braking resistor on the 'Filter' board, and an inhibit wire completely off its terminal on the forward/reverse switch, making intermittent contact. After tightening and/or remaking all affected connections, it was much improved but still not right below 300 RPM. The remaining issues were due to poor wiper contact in the speed control pot, and stripping it, cleaning the track and contact ring and re-tensioning the contacts resulted in the motor now running smoothly over the full speed range. The speed is slow to settle, and while part of that is probably the lag in the digital tach, I suspect that the KBIC motor speed controller isn't properly tuned as it was (allegedly) previously replaced.<br />
<br />
===Drive belt slipping===<br />
* Fixed 28/9/2022: During testing the motor after the above issue, it was noted that the chuck could be stalled, slipping the drive belt, with not much torque. The drive belt was determined to be loose and a bit worn, but still in acceptable condition. <br />
<br />
: Access for servicing the belt requires removing the control box ''(2 spades to ZVR switch disconnect the supply, speed sensor and motor simply unplug from the 'filter board')'', the motor cover, chuck guard switch assembly + wiring cover, the change gear 'A' (drive) shaft carrier assembly, and the tumbler gear assembly. See https://youtu.be/EkxlIz01BdA for disassembly/reassembly, though on our lathe, the speed encoder ring on the spindle prevents the belt cover from being fully removed without disturbing the spindle nuts. There is enough room to work with it loose, but still trapped by the encoder ring. Also, unlike the video, if the 'jack' screws under the headstock are correctly adjusted, and the studs aren't excessively bent, there is no need to make custom studs. <br />
<br />
: It turns out that our lathe was missing the M6 hex headed jack screws that press the motor down to resist the belt tension, and the motor had cocked out of position at a severe angle. I know Ian B had had considerable trouble adjusting it after the motor fault back in October 2022, and I believe it had been getting slowly worse ever since. The jack screws were probably mistaken for headstock fixing bolts during disassembly after the crash that resulted in the metal Hi/Lo gears being fitted, then lost. The penny washers on the studs had dished, so I turned them over and backed them up with smaller washers and switched to Nyloc nuts so they cant back off due to vibration. N.B. There is a packing washer on the motor side on one of the studs, presumably so the shaft is true to the ways. Adjusting the motor is awkward to say the least. One has to slack the stud nuts off a lot, pry under its rear end to lift it enough to be parallel to the ways, snug the stud nuts, check alignment, then set the jack screws and their lock nuts to hold it there, and finally tighten the stud nuts. <br />
<br />
: Tension: According to Sieg, it should be possible to twist the belt 90° mid span with a light finger grip. Other sources say 1/32" - 3/32" deflection mid span with light finger pressure.<br />
<br />
===Speed display blanking===<br />
* The speed display has been intermittent, blanking and flashing 8888 and 0 at certain speeds for as long as I have been using the lathe. Finally on 18/07/2022 it failed completely, with no display. I removed the display module and bench tested it - the pins are labelled 5V GND PL PE, PE is frame ground and PL is a TTL level pulse from the speed sensor - confirming that it was in good working order. My suspicions then turned to its power supply on the 'Filter' board. With both the sensor and display unplugged, the 5V rail was found to have a only a couple of volts, but the unreg DC was 17V and stable. Replacing the 78L05 5V regulator restored the 5V rail and normal operation.<br />
<br />
: ''I conclude its been failing for a while with high load current due to speeds with more lit segments causing it to drop out, resetting the speed display, causing it to blank, lowering the current enough for the regulator to recover, then the display MCU lamp tests (8888) then re-acquires the speed, repeating ad-nauseum till the speed is changed. I don't like the design as the high input voltage results in excessive dissipation.'' <br />
<br />
: ''ToDo: If it fails again, bench test display to measure its worst case current consumption, then fit an appropriate dropper resistor to reduce the 78L05 dissipation.''<br />
<br />
===Quill spinning when drilling===<br />
* The quill was tending to spin while drilling because its anti-rotation pin (a M5 dog tip setscrew) was sheered. I've removed the debris, aligned the scale with the top of the tailstock and fitted a longer M5 dog-tip setscrew to replace it, with a nut to lock it at the correct height. N.B. the pin isn't that 'meaty' so if using big drills in tough metals, to prevent shearing it, it should be backed out so the quill can be turned by hand and unwanted rotation controlled by being quick with the quill lock if it starts to spin, or even using a close fitting rod in one of the chuck key holes with plastic tube over it to protect the ways. <br />
: ''If the screw sheers again, the quill will need to be removed and the tailstock taken off the lathe so the sheered tip can be shaken out, and if the setscrew is difficult to remove it probably means the threads are mangled where it sheered. Try driving it right through with the quill out.''<br />
<br />
===Sloppy quick change toolpost locking mechanism===<br />
* Once the dovetail clamp screw was slackened, there was nothing preventing the dovetail twisting or cocking significantly, and friction with the toolholder made it tend to do so, making toolholder insertion and removal more difficult unless the clamping screw was backed off excessively. I added a compression spring around the clamp screw inside the toolpost to push the dovetail outwards so it mostly retains alignment when open, allowing toolholders to slide on or off cleanly with far less screw slackening.<br />
<br />
===Leadscrew rubbing===<br />
* The leadscrew shaft is rubbing on the insulating separator inside the control box. Unfortunately the corner of the relay on the Filter Control Board (#160) doesn't allow enough clearance. Although the friction isn't much of a problem at high reduction ratios, e.g. 16:1 power feed, it increases the stress on the change gear train, and may be problematic when threading at feeds above 1:1. ''Possibly pack out the control box mountings by a couple of mm.'' <br />
<br />
===High/Low lever backwards!===<br />
* The high-low drive gear selector behind the headstock is incorrectly labelled and differs from the manual: low gear (which we normally use) is with the lever towards the tailstock. ''I suspect that the gears in the headstock were refitted the wrong way round when it was upgraded to metal gears.''<br />
<br />
: ''ToDo: Get it reassembled the right way round during the spindle bearing upgrade!''<br />
<br />
===Carriage lock fouls top slide===<br />
* The T handscrew has been replaced with a M5 hex headed bolt, to permit access when the top slide is over it. An 1/4" drive 8mm socket is usually left on it, but needs to be removed when the full cross slide travel is needed. The small (4 jaw) chuck key is near enough 1/4" to use for it. If you need to (un)lock it while the compound is over it, you'll need an 8mm spanner. ''The [https://www.amadeal.co.uk/acatalog/Mini-Lathe-Carriage-Lock-463.html Amadeal lock screw] is in the spares tin as it was too high and fouled the compound slide.''<br />
<br />
===Tailstock locking lever loose===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock - See full image for key to screws]]<br />
* Diagnosed and fixed 10/1/2023 - In the base of the upper section of the tailstock, there are two dog tip set screws that engage with locating grooves in the counter-rotating shafts carrying the eccentric locking cams. They'd backed off, probably due to vibration. They need to be tightened till they bottom out in the groove, making sure they are '''in''' the groove, backed off half a turn so the shafts can turn easily, and locked in place. There's no facility to do so, so reassemble with weak threadlocker. Unfortunately to get to them you have to remove the tailstock base slide, which is held on by the pressure of four adjusting grub screws, which all need backing off, and one socket headed bolt from underneath so full tailstock realignment is required after reassembly, which even for a rough alignment is tedious.<br />
: <s>The tailstock locking lever is loose and can be pulled out on its axis. It works OK when fully pushed home but needs investigating. ''I tightened the grub screw as the lever was coming off its shaft, but the whole shaft pushes/pulls in and out. It works OK fully pushed in, but it seems something that is meant to retain it has failed inside the tailstock base.</s><br />
<br />
===Gear alignment issues===<br />
* Change gear alignment is poor. I've currently got a gapped washer (to clear the key) packing out the A shaft so the gears line up, but this reduces the key's engagement so is problematic due to the high loading if the gears are set up for coarser threads. <s>Also I need to turn down some penny washers to slightly less than the root diameter of the metal 20T pinions, as gear retaining washers.</s> ''The gear retaining washers for A gear and B-C stub shaft are now done, turned down to slightly under 16 mm dia. Spares in the change gear tin. ToDo: The D (leadscrew) washer requires a larger center hole, so make two more with that hole.'' <br />
<br />
===Saddle gibs loose===<br />
* Fixed 11/04/2023: I took the apron off for access (and to clean the carriage handwheel gears), and found the front sheer plate screws were completely loose. I've snugged them up some and set the opposing grub screws and got a lot of the slop out. I've re-checked the front ones, and taken up the slop in the rear ones - Unfortunately it wasn't possible to get carriage movement to have an even 'feel' over its whole travel, and its noticeably tighter near the tailstock. If light hand pressure on the side of the unlocked carriage can cause movement (with the half-nuts open), its time to readjust them again, though it should be possible to move the carriage with a firm push. <s>The saddle gibs (actually the sheer plates) were too loose, to the point that engaging a slightly stiff threading dial could cause it to self-feed, an obvious crash hazard if working near the chuck or a step in the work.</s><br />
<br />
''N.B. the lefthand front opposing grubscrew is short, (fully recessed) and unlike the others does *NOT* have a locking nut as it must clear the traverse pinion. A wrap of PTFE tape provides enough friction to keep it in place, though possibly a bit of nylon fishing line down its hole would be better.''<br />
<br />
===Excessive cross-slide backlash===<br />
* ''Fixed 21/11/2023.'' Originally, back in October 2023, The cross-slide screw had excessive backlash (nearly three turns), which increases the risk of loosing track of the cut depth when cutting steps, and during threading operations. If you ended up off by a turn too far in, a crash would be the most likely outcome.<br />
: The original excessive backlash was traced to loose cross-slide screw nut mountings. The nut has two socket headed cap screws pulling up, one either end, accessible from the top of the cross-slide, which control the tilt of the nut to take up backlash in the nut, and an opposing grub screw pressing down on the center of the nut to make it longitudinally rigid. Snugging up the grub screw reduced the backlash to 10 divisions or so, or 0.25 mm. A year later, the backlash had increased to one turn due to the cross-slide nut mounting screws working loose again.<br />
<br />
: 07/11/2023: I investigated further: It is difficult to get the cross-slide nut aligned correctly as it must be at the same height as the screw which is constrained by the bearing surfaces in the bracket. With the cross-slide almost at the front limit of its travel, I removed the screw and set the nut as level as possible and visually centered in the bore, then re-fitted the bracket and screw, then adjusted the tilt till it turned freely through the backlash. I then tilted it up at the front till some drag was felt to minimise the backlash and tightened the screws to lock it in place balancing them to maintain the same feel as I tightened them. The result was 7 divisions of backlash, acceptable but not great. During normal turning operations, the load on the nut is tension on the front screw and pressure on the grubscrew, so if it slackens again due to vibration from chatter, odds are it will be the rear screw that's loosened.<br />
<br />
: 16/11/2023 - 21/11/2023: The backlash had crept back up to 11 divisions (0.275 mm). We don't have any >14 mm brass stock (or even near that) so I tried making the shim washer out of aluminium. I was shooting for 0.24 mm but due to poor technique got 0.28 mm. No good - locked solid. I lapped it down and tried it till I got it down to 0.20 mm which gave about 3 divisions backlash - good enough, but the screw was too tight due to the shim washer not being bevelled at its outer edge resulting in it cupping in its seat. Filing a bevel round the OD and re-lapping it resulted in a 3 - 4 divisions of backlash. Its a little mushy due to the washer having been kinked removing it, so ideally a new (brass) washer should be made. <br />
<br />
* Further reduction of backlash: https://youtu.be/Wu_tI29JL2Y?t=163 <br />
: Brass tinned with Pb-free solder to form a white metal bearing surface should work at least as well as the bronze used in the video. The shim washer needs to be 10.2mm ID, with a full thickness bevel on a 14 mm OD. It isn't necessary to remove the lead screw from the cross slide, as the washer can be fitted in-situ with only the bracket removed.<br />
<br />
===3 Jaw chuck didn't mount properly===<br />
* Fixed 7/4/2023 by grinding the spindle nose lip. The three jaw chuck can now be installed and removed by hand with no hammering. A test bar in it now has only 2 thou runout (TIR) at the chuck.<br />
: <s>The three jaw chuck and the faceplate aren't seating properly on the spindle nose. Its too tight on the register diameter of the lip. This results in grossly excessive runout, and also makes this chuck and the faceplate a PITA to fit or remove.</s><br />
: ''The spindle nose had been abused with a hammer (before my time) which mushroomed it and may have brinelled its bearings. See '''Excessive Runout''' and '''Spindle bearings''' above.''<br />
<br />
== Manuals, Books and other resources ==<br />
=== Manuals ===<br />
The [https://wiki.richmondmakerlabs.uk/images/a/a3/Lathe_InductionNotes.pdf RML CJ18A Mini-Lathe Induction Notes]. Your mandatory Lathe Induction will cover most of this but its good to be able to refer back to it.<br />
<br />
Official [https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Amadeal CJ18A Manual], or paper copy (less complete) kept on shelf above lathe.<br />
<br />
The [https://www.chesterhobbystore.com/wp-content/uploads/2022/11/Conquest-Super-Lathe.pdf Conquest Super Lathe manual] is considerably better than the Amadeal manual and is for a near-identical machine.<br />
<br />
The [https://littlemachineshop.com/images/gallery/info/minilatheusersguide.pdf Mini Lathe User’s Guide] from LittleMachineShop.com is even more comprehensive, going into its usage in some detail, with a proper TOC, and covers both US and Metric versions of Realbull Mini-lathes. ''The only fly in the ointment is the threading section assumes a US lead screw so change gear selections and threading dial divisions will not be correct for our lathe.''<br />
<br />
[https://www.arceurotrade.co.uk/machineguides/C3-Mini-Lathe-Dismantling-and-Reassembly-Guide.pdf Sieg C3 Mini-lathe Dismantling and Reassembly Guide] "A picture story book to help you dismantle and reassemble your Sieg C3 Mini-Lathe" ''It is similar enough to ours to serve as a maintenance guide, except for the electronics, spindle drive and other headstock innards.<br />
<br />
The motor controller is a clone of a [https://acim.nidec.com/drives/kbelectronics/-/media/kbelectronics/documents/dc-drives/manuals/kbic_manual.ashx?la=en KBIC® SCR DC Motor Speed Control]<br />
<br />
=== Books ===<br />
'''Metal Turning on the Lathe''', by David A Clark, Crowood Metalworking Guides, ISBN-13: 978-1847975232 [https://www.amazon.co.uk/gp/product/B00E78RKIG Kindle Edition (£8.99)]. ''A 'free' epub can be googled for, *NOT* linked here due to dubious legality.''<br />
<br />
'''[https://archive.org/details/03screwcuttinginthelathe Screwcutting In The Lathe]''', by Martin Cleeve (a pen-name of Kenneth C Hart), Workshop Practice series #3, ISBN-13: 9780852428382<br />
<br />
'''[https://archive.org/details/15workholdinginthelathe Workholding in the Lathe]''', by 'Tubal Cain' (a pen-name of Tom Walsh), Workshop Practice series #15, Argus Books, ISBN-10: 0852429088<br />
<br />
'''[https://archive.org/details/20metalworkandmachininghintsandtips Metalwork and Machining Hints and Tips]''', by Ian Bradley, Workshop Practice series #20, ISBN-13: 9780852429471<br />
<br />
'''[https://archive.org/details/38toolandcuttersharpening Tool and Cutter Sharpening]''', by Harold Hall, Workshop Practice series #38, ISBN-13: 9781854862419<br />
<br />
'''[https://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpaperT204.pdf Cutting Fluids]''', by EC Bingham, NIST Tech. Paper No. 204, 1921<br />
<br />
=== WWW resources ===<br />
==== Mini-lathe Specific ====<br />
There's a *LOT* of mini-lathe info online. Notable sites include:<br />
* http://www.mini-lathe.com/ - A major Realbull/Sieg mini-lathe resource.<br />
* http://mikesworkshop.weebly.com/lathe-modifications.html - many mods including carriage DRO autostop, and variable speed leadscrew motor drive, cross-slide motor drive, etc. He also has a page with a bunch of accessories, toolholders etc. - http://mikesworkshop.weebly.com/lathe-accessories-and-tooling.html<br />
* http://andysmachines.weebly.com/variable-speed-controls.html - Scroll down to the 'UPDATE' section for the schematic of a very similar SCR speed control board. It also has the schematic for an earlier version of the Auxiliary Control Board (aka: 'Filter' board).<br />
* https://www.youtube.com/watch?v=WbJM9ooveo8 - A video tour of a very very similar mini-lathe. Significant differences: ours has a 4" longer bed, a quick change toolpost, a different tailstock, no DRO (apart from basic spindle speed, so skip 16:12 to 28:50 in the video), larger chucks and a carriage lock.<br />
<br />
==== Forums ====<br />
''with publicly accessible archives''<br />
* https://groups.io/g/7x12MiniLathe - Mini-lathe specific, active<br />
* https://www.hobby-machinist.com/forums/mini-lathe-mini-mill-information.220/ - active<br />
==== Youtube Playlists & Videos ====<br />
* Blondihacks: [https://www.youtube.com/playlist?list=PLY67-4BrEae9Ad91LPRIhcLJM9fO-HJyN Lathe Skills] (playlist) - "This is an educational series to help you learn to use your metal lathe. Watch them in order for best results! Satisfaction not guaranteed, especially if you're a cranky sort of person."<br />
* Frank Hoose (Minilathe.com) has a couple of relevant Youtube playlists:<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn7ON0jGM5UbM-KZDT56MOIp Mini Lathe Operations]<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn4nGRZaVq3wTOlvZNOmdAZ2 Mini Lathe Overview]<br />
<br />
==== General Machining ====<br />
* https://www.machiningdoctor.com/ - "THE #1 MACHINING TECHNICAL HUB"<br />
<br />
==Projects==<br />
[[File:VESA mount.jpg|thumb|Machined VESA mounting plate (left) and plate from Dell monitor stand it must match (right). The translucent washer shows the size of the original center hole.]]<br />
* My first faceplate project was boring out the center hole in a VESA mounting plate to adapt it to fit onto a surplus Dell 1708FP monitor stand. The part was centered using the tailstock dead center engaging with its original center hole. I clamped the part with studs and penny washers on the driving side of two opposite corners, with cap screws in the next slot round to trap the corners under the clamping washers, then withdrew the tailstock and dead center. After machining out the bore, I used the tip of the tool, rotating the chuck by hand, to scribe a circle for laying out the bolt holes. I finished off laying out and drilling the bolt and locating holes by hand at home, fitted it to the stand, and mounted the 2nd hand LG 24" widescreen monitor.<br />
<br />
* Another ultimately unsuccessful project was fly cutting aluminum flat bar to thickness to make custom shims for the set of carbide insert tools, for the four way toolpost. The 8 mm shank tools need ~2.5 mm shim stacks, and the 6 mm shank tools need ~4.5 mm shim stacks. Ideally I'd machine single shims, but the only stock I've got handy cleans up to only 3.2mm, and some fine shimming may be needed to fine-tune the tool height.<br />
<br />
: After sorting out the clamps so they were no longer twisting the aluminum flat bar stock, and switching to the short 45° turning SCMT06204 insert tool in the four way toolpost, to improve rigidity and get a well controlled tip radius, the finish was much improved. I'm still having problems getting an even thickness and am getting approx. 0.05mm variation, I suspect due to the aluminium bar stock distorting due to internal stresses as its surface is cut away. ''ToDo: try supergluing the stock to the faceplate before clamping to further reduce chatter and stop the warping.''<br />
: Looking back on this project a year later, its fairly obvious that the thickness variation was probably due to faceplate surface runout due to the damaged spindle nose.<br />
<br />
* Raphael has been working on a steel rocket nozzle with some assistance from myself. We have set up the rough cut chunk of ~ 50mm steel bar, faced both ends (to 50mm length) and turned the OD to 49mm to clean it up. Its going to need through drilling, probably some boring, and quite a bit of detail work on the OD. It will then need to be transferred to a jig in the drill press vice to allow a pattern of angled traverse holes to be drilled with acceptable accuracy.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_Lathe_Notes&diff=17615Ian M's Lathe Notes2024-02-07T13:06:07Z<p>IanM: /* Tungsten Carbide Insert Tools */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br />
<br />
''Currently these notes are semi-organized and non-authoritative. As I become more experienced with the RML CJ18A mini-lathe, I'm cleaning up, extending and reorganising them. Some lathe operating experience is assumed. If in doubt, '''*ASK*''' me, Andy H<sup>*</sup> , Jonathan H or another experienced minilathe operator!<br />
<br />
''* Andy H should be asked (for an authoritative answer) any questions involving RML usage policies or acquiring tooling or materials through RML.''<br />
<br />
== The Lathe ==<br />
Our Facilities page [[Facilities#Lathe|has]]:<br />
<blockquote><br />
'''Lathe'''<br />
[[File: Lathe2.jpg |200px|right | Lathe]]<br />
In the kitchen. <br />
<br />
Marked as a CJ18A Mini-Lathe from [[https://www.amadeal.co.uk/acatalog/CJ18A-Mini-Lathe-7x14-Machine-100mm-3jaw-Metric-With-Metal-Gears-AMA_LA_CJ18_M_3_MGRB.html Amadeal]]<br />
[[https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Manual]] <br />
<br />
[[Media:Lathe InductionNotes.pdf| Induction Document]]<br />
<br />
Possible upgrades:<br />
*https://www.youtube.com/watch?v=GwT-JQLbNPA<br />
<br />
''Please do not use the lathe until you have received induction'' <br />
<br clear=all><br />
</blockquote><br />
Its a Chinese import 7x14 mini-lathe. The 7x14 refers to the maximum diameter and length of work, in inches and is only a theoretical measure of the working envelope as you loose length to the chuck + any tailstock tooling, and the diameter is over the bed, not the cross-slide. See actual specifications below. <br />
<br />
Most if not all Chinese 7x10 to 7x16 mini-lathes seem to be remarkably similar (not uncommon with Chinese products due to [https://www.bunniestudios.com/blog/?p=284 Shanzhai (山寨)] )<br />
and the OEM of our Amadeal CJ18A Mini-Lathe was probably [https://www.made-in-china.com/showroom/cheap-lathe Yangzhou Realbull Machinery Co. Ltd]. Very similar lathes are also made by [https://www.siegind.com/lathe-machine.html Sieg], but their lathes tend to be slightly less sophisticated than the equivalent Realbull models.<br />
<br />
''N.B. Many Sieg parts are known to have slight but critical differences from Realbull parts, so '''DON'T''' order Sieg spares for a Realbull lathe!<br />
<br />
== Key Specifications ==<br />
Amadeal says the CJ18A Mini-Lathe is a 7x14 model with:<br />
<blockquote><br />
* Power 550 W<br />
* Distance between centres : 350 mm<br />
* Swing Over Bed: 180 mm<br />
* Swing Over Cross Slide: 110 mm<br />
* Taper: MT3<br />
* Tailstock Taper: MT2<br />
* Chuck diameter: 100 mm<br />
* Spindle Speed: 50 - 2500 rpm ''(with digital readout)''<br />
* Spindle Bore: 20 mm<br />
* Cross slide Travel: 65 mm<br />
* Range of Metric Threads: 0.5 - 2.5mm.<br />
</blockquote><br />
* The lead screw is metric, pitch 1.5 mm.<br />
* The spindle center is 90.6 mm above the flat of the bed (measured).<br />
<br />
Even though the compound and cross slide handwheels appear to be calibrated in thousandths of an inch, as ours is a metric machine, they only approximate that. One turn of a slide handwheel is 1mm advance, and they have 40 divisions, so each division is 0.025 mm, (approx. 0.984 [https://en.wikipedia.org/wiki/Thousandth_of_an_inch thou]). Similarly, the tailstock quill advances 1.25 mm per handwheel turn, which has 50 division dial, giving the same 0.025 mm divisions, but only 4 turns per 5 mm. The carriage handwheel is awkward - it moves approx. 19.2 mm per turn, and doesn't have a dial scale.<br />
<br />
== Notable Accessories ==<br />
We have:<br />
* [https://www.amadeal.co.uk/acatalog/160mm-Face-Plate-for-the-4-Mini-lathe-AMA_AC_CJ18A_FP160RB.html#SID=129 160 mm (6 1/4") Faceplate]<br />
* 100 mm (4") three jaw self-centering chuck (OEM standard) 22.5mm bore, with inside and outside jaw sets<br />
* 100 mm (4") four jaw (independent) chuck with reversible jaws (8 TPI screws)<br />
* Tailstock drill chuck (max. 13 mm dia.)<br />
* Live center for tailstock (+ OEM fixed center) <br />
* Four way Tool Post (OEM Standard)<br />
* [https://www.amadeal.co.uk/acatalog/Quick_Change_Tool_Post_for_the_mini-lathe.html Quick Change Tool Post] + 3 tool holders<br />
* [https://www.amadeal.co.uk/acatalog/Fixed-Steady-for-Mini-Lathes-AMA_AC_CJ18A_FSRB.html#SID=145 Fixed Steady Rest]<br />
* [https://www.amadeal.co.uk/acatalog/Travelling-Rest-for-Mini-Lathes-AMA_AC_CJ18_TSRB.html#SID=144 Travelling Steady Rest]<br />
<br />
''You'll find all of the above on the shelf above the lathe, with the accessories in the wooden box, apart from the steadies, which live next to it. Change gears, spare parts, and most cutting tool tips/blanks are in labelled white rectangular tins behind the lathe.''<br />
=== Measuring Tools ===<br />
We have:<br />
* Various dial indicators - the one with the adjustable magnetic base stand is the most convenient for most lathe setup work.<br />
* 25mm micrometer (in little grey case)<br />
* Grey case containing set of measurement tools including dial calipers, micrometer, steel rule (metric & inch), engineers square, and a fish-tail gauge<br />
<br />
''We currently lack''<br />
* ''A tool height setting gauge''<br />
<br />
=== Hand Tools ===<br />
Some common tools needed for normal use are kept with the lathe, in or attached to the wooden accessories box:<br />
* 2 mm Allen key - adjusting cross-slide and compound gibs<br />
* 4 mm Allen key - quick change toolholder tool clamping screws + height adjust, tightening dials<br />
* 5 mm Allen key - four way toolpost tool clamping screws, engaging/disengaging threading indicator<br />
* 6 mm Allen key - locking/unlocking quick change toolholder<br />
* 8 mm spanner - locking carriage when 8 mm socket can't be used, locking gib adjuster nuts <br />
* 13 mm spanner - changing chucks, locking steady rest jaws<br />
* Very long needle nose pliers - for grabbing swarf safely, holding one end of emery cloth safely so you can keep your fingers away from the jaws, and extricating small objects from awkward places.<br />
<br />
== Change Gears ==<br />
[[File:BC puller 1.jpg|thumb|Custom puller for B-C stub shaft]] [[File:BC puller 2.jpg|thumb|Pulling the B-C stub shaft]]<br />
See "Conquest Super Lathe" manual ([[#Manuals|below]]), section '''4.7 Change Gears''', PDF pages 28-29, but see below for mesh adjustment. The LittleMachineShop.com "Mini Lathe User’s Guide" (also below) section '''Threading''' gives a far better explanation, with pictures and diagrams, but its for a lathe with a US 1/16 inch pitch leadscrew, not a metric 1.5 mm pitch one like ours, so you *MUST* ignore all the tables in that section, replacing them with metric mini-lathe (with 1.5 mm pitch leadscrew) equivalents. <br />
<br />
We have the following tooth count gears: 20,20, 30, 35, 40,40, 45, 50,50, 60,60, 80,80<br />
which consist of the OEM power feed gears + the metric change gear set. Apart from the metal 20 tooth pinions, they are all plastic, probably Delrin if the molded in 'POM' marking can be trusted, but possibly plain Nylon 6, and are metric Module 1.<br />
<br />
If we wanted to add the capability to cut US/Imperial threads we'd need to buy additional 55, 57 and 65 tooth gears, and possibly a 21 tooth metal pinion.<br />
<br />
CGTK's [https://www.cgtk.co.uk/metalwork/calculators/changegears/minilathe?gears1=20,20,30,35,40,40,45&gears2=50,50,60,60,80,80&gears3= Change Gear Calculator] ''(link preloaded with our gear list)'' is useful if you don't want to calculate the ratios from first principles. Not all suggested combos will physically fit.<br />
<br />
* Take care *NOT* to loose the keys in the A and D shaft keyways - turn each shaft till the keyway is up before removing the gear. <br />
* The B and C gears are coupled by a hollow stub shaft (with an integral key), which is so tight in the gears it has to be pressed or driven out - I've made a puller just for this task, kept in the change gears tin.<br />
* The center of the B-C stub shaft *MUST* be lubricated where it runs on its pin on the change gear banjo bracket, with grease or heavy oil. ''Seizure of the stub shaft due to running dry is a frequent cause of catastrophic mini-lathe geartrain failures!''<br />
* Don't get oil on the change gears as it can cause plastic gears to crack. Only PTFE drylube or plastic compatible white grease should be used on their teeth. <br />
* Adjust the B-C pin position in the straight slot first to set the C to D gear mesh, tighten its nut, then swing the whole banjo about the D shaft boss to set the A to B mesh, and finally tighten the banjo clamping nut.<br />
* Check both gear meshes have running clearance by turning the chuck by hand enough to complete one full turn of the leadscrew, and by attempting to turn the intermediate gear(s) to assess backlash, If excessive resistance is felt or if there's significant backlash, readjust the gears. If you have difficulty judging the mesh, a strip of 80 gsm copier paper (approx. 0.1 mm thick) wound into the meshing teeth before tightening the stud or banjo will give appropriate clearance once removed. Once setup, check the gears run quietly under power.<br />
* If the sum of the tooth counts C+D is the same as for the ones you just removed and they were correctly meshed, you don't need to move the stub shaft pin. If A+B is <u>also</u> the same, you don't need to move the banjo. e.g. If it was set up for 16:1 reduction power feed, 1 mm (40:60 - 50:50) for M6 and 1.5 mm (e.g. 40:60:40) for M10 pitches can thus be achieved by only swapping gears. <br />
<br />
''The change gears, puller, etc. and a box spanner for the banjo nut are kept in a white rectangular tin behind the lathe.''<br />
<br />
=== Power Feed ===<br />
When used for turning with power feed, the change gears should be set for a 16:1 reduction (A:20 : B:80 - C:20 : D:80) using the pair of small metal 20 tooth pinions and the 80 tooth plastic gears (largest in set), for a feed of 0.09375 mm per turn (1.5 mm/16). Unless continuing your threading project the next session, please re-fit the 16:1 power feed set after threading so the power feed is ready for use. <br />
<br />
* *ALWAYS* leave the feed direction selector lever in its neutral (no feed) position, and the half-nuts open after use.<br />
* *ALWAYS* check the carriage lock is disengaged before engaging power feed. Unlock the carriage after use. <br />
<br />
=== Threading Dial ===<br />
The threading dial is an aid to re-engaging the half-nuts at the right moment so the tool will retrace its previous path cutting deeper, rather than offsetting axially some fraction of the thread pitch and ruining your work. Its based on the concept of the lowest integer multiples of the leadscrew and thread ''(being cut)'' pitches that exactly match, but for mechanical simplicity it only covers certain selected multiples of the leadscrew pitch.<br />
<br />
We have a choice of three pinion gears:<br />
{| class=wikitable<br />
|+ Threading dial Pinion Gears<br />
|-<br />
! Teeth !! Colour Dot !! Usable lines !! OD gear !! Dist. per turn<br />
|-<br />
| 14 || Red || 1,7 || 7.51 mm || 21 mm<br />
|-<br />
| 15 || Orange || 1,5,9 || 8.05 mm || 22.5 mm<br />
|-<br />
| 16 || Green || 1,4,7,10 || 8.37 mm || 24 mm (2 mm/div)<br />
|}<br />
They are now colour coded, with a paint dot on the gear end face ''(the only non-wear surface)''. The 16 tooth one is normally left on the lathe, but disengaged when not threading to minimise wear on the lead screw. The others are kept in the Change Gear tin.<br />
<br />
There's a threading dial 'pickup' calculator here: https://www.cgtk.co.uk/metalwork/calculators/threaddialindicator <br />
<br />
Initially select ''Lathe:'' '''Custom''', and enter the following below:<br />
* ''Units:'' '''Metric'''<br />
* ''Lead Screw Pitch (mm):'' '''1.5'''<br />
* ''Thread Dial Indicator Gear Teeth:'' '''16,15,14''' <br />
* ''Lines on Thread Dial Indicator:'' '''12''' <br />
* ''Line Marking:'' '''Every Line Numbered'''<br />
Note the teeth list is entered in reverse order so the resulting table highlights any required pinion changes.<br />
<br />
N.B. The dial is only friction clamped to the pinion by its center screw. If you have any reason to suspect it may not be properly aligned: <br />
# With the power off and the carriage unlocked, engage the feed direction lever upwards. You'll probably need to turn the chuck by hand to get it to engage.<br />
# If the threading indicator isn't already engaged, loosen the threading dial support block bolt, pivot the block to engage the pinion with the leadscrew and retighten the bolt.<br />
# Engage the half nuts, again turning the chuck by hand till they drop in. <br />
# Turn the chuck a couple of turns, top towards you to take up any backlash, then lock the carriage, taking care not to push it left while locking it.<br />
# Loosen the screw securing the dial to the pinion.<br />
# Align the '1' line of the dial with the index line, by rotating the dial clockwise, then retighten the screw.<br />
# Don't forget to disengage half-nuts and unlock the carriage!<br />
<br />
The above instructions should result in the half-nuts engaging cleanly when exactly on any valid line when threading towards the headstock. If it is required to thread away from the headstock, there will be a slight offset from the line due to backlash between the spindle gear and leadscrew, so engage slightly early.<br />
<br />
Changing the pinion:<br />
# Loosen the threading dial support block bolt and disengage from the leadscrew.<br />
# Undo dial center screw, and remove it and the dial, dropping the old pinion out the bottom.<br />
# Oil the shaft of the new pinion with a drop of light oil and insert it from below, gear end down.<br />
# Refit dial and screw.<br />
# Check the dial and pinion turn freely with minimal resistance.<br />
# Align as above.<br />
<br />
== Tailstock and Steadies ==<br />
These are mostly used to support long work ''(long with respect to its diameter)'' to improve rigidity, increasing accuracy and reducing chatter. The Tailstock quill is also used with a drill chuck for drilling.<br />
=== Tailstock ===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock base]]<br />
The tailstock can be offset to turn shallow tapers between centers. We don't currently have the accessories to turn between centers, namely <s>a MT3 dead center for the spindle, or</s> any drive dogs for the work. Also realigning the tailstock after turning a taper can be a PITA. The photo shows the tailstock adjusting screw locations ''(C - Lateral, and D - Skew)'' and the block on the baseplate they engage with. Adjustments can only take effect when the tailstock locking lever is eased to take the pressure off the baseplate. As we don't have a MT3 center, one has to turn a fresh point on a test workpiece for a rough tailstock alignment reference. Fine alignment, to avoid inadvertent taper turning, can be done by mounting a long precision ground bar between the chuck (or preferably a center in the spindle), and a dead center in the tailstock and sweeping it with a dial indicator on the carriage. Finally a test cut should be taken at either end of a bar between centers, and the diameters checked with a micrometer. Assuming the bed has previously been properly levelled and shimmed to take out twist ''(not the case at RML as we don't have it bolted down)'', any remaining difference in diameter will be double the tailstock offset, smaller at the tailstock being offset towards the front. Fine adjustment cant be achieved by jacking with the screws, its best to ease the adjusting screws, bump the tailstock into alignment then take up the screws again, checking the alignment is maintained when the tailstock is unlocked and relocked. There is no vertical adjustment, though shims can be added between the tailstock and its base.<br />
<br />
==== Tailstock Quill ====<br />
There is a metric/imperial scale on the top of the quill, read against the end of the tailstock, for depth measurement when drilling. The tailstock quill has a 1.25 mm pitch thread and a 50 division dial. Each division is therefore 0.025 mm, and it only takes 4 full turns of the handwheel to move the quill 5 mm. <br />
<br />
To eject MT2 taper tooling and centers from the tailstock, wind the quill all the way in.<br />
<br />
N.B. The quill anti-rotation pin (dog-tip setscrew + locking nut in top of tailstock near to the quill lock) is only M5. It will sheer if a large diameter drill jams in the work. Please back it out clear of its keyway if using large drills, and use alternative methods of preventing chuck rotation. To re-engage it, crank the quill out till you can see the keyway, align it with the screw and screw in the screw till it gently bottoms out, then back it off a quarter turn. Try twisting the quill to check its properly engaged, then tighten the locking nut gently to hold the screw in position clear of the bottom of the keyway.<br />
<br />
=== Steady Rests ===<br />
We have two, both with brass tips that must be kept lubricated during use.<br />
<br />
The fixed steady mounts on the ways, and is most useful when turning longer work that wont fit through the spindle bore. Adjustment is critical, and the surface the tips run on must be smooth and concentric, as any misalignment that forces the work off center will result in the work wobbling in the chuck, marring it, with a high risk of it becoming un-chucked, which can be dangerous at speed.<br />
<br />
The travelling steady mounts to the headstock side of the carriage to locally resist the deflection of thin long work, due to the cutting forces. It only has two tips, to resist climb, and deflection away from the tool, and requires readjustment after every cutting pass.<br />
<br />
== Tooling and Tool Holders ==<br />
'''Key dimensional data:'''<br />
* The quick change holders accept up to 10 mm shank tools. <br />
* The four way toolpost has 50 mm long sides, a seat width of 15 mm and can clamp tools of up to 5/8" (15.875 mm) shank ''(check this)'', but the slot base is only 10.4 mm below the spindle center so cannot be used with >10 mm shank tooling unless it has a dropped tip. Large tooling with a centered tip is also problematic as you run out of height above the shank when trying to shim to match the spindle center height. <br />
<br />
===Quick Change Toolpost===<br />
I've got the quick change toolpost and toolholders setup for mostly easy use. The three toolholders came with cantilever height setting arms which historically haven't been installed as the supplied fixing screws were too short. That's all now sorted out and a HSS RH turning tool and a HSS hand-ground grooving/parting-off tool are now mounted in two of the holders and set to height. The third is kept free for other tools. <br />
<br />
The quick change toolpost has been modified with a spring to press the dovetail clamp outwards and help stop it twisting or flopping about to ease toolholder fitting and removal. The dovetail clamp (socket headed screw on toolpost side opposite dovetail) feels a bit stiffer than before, but will take less than half a turn to go from open (with the toolholder lifting out or dropping in easily) to fully clamped. As there is so much less clearance in the open position you should no longer need to wiggle the toolholder while clamping it to get a consistent height. If the dovetail clamp ever gets misaligned, twist it straight by eye, slacken off a bit further than usual to get a toolholder on, clamp it to align the dovetail then release, reseat the toolholder and re-clamp to ensure its at its preset height. You cant adjust the height by 'jacking' with the height screw due to its offset leverage. Instead, back off the height screw and hold the toolholder at the desired height while locking the dovetail clamp, then adjust the height screw (and locking nut) to hold it there, then check it doesnt change height significantly when you unclamp and reclamp the dovetail. <br />
<br />
Unfortunately the OEM height setting screws foul the toolpost locking nut handle. Currently, if you need to swap toolposts you will have to first remove the quick-change tool holder from the post. There is enough nut handle swing to allow the quick change toolpost to be unclamped and rotated to fine set the tool angle without removing the toolholder. It also seems the mating surfaces may be slightly out of square, as if you rotate the toolpost 90° or 180°, the nut swing may be insufficient to re-clamp it without removing the toolholder to do so. Add a M10 washer under the locking nut if the handle ends up pointing in an undesirable direction! A thin M10 washer is kept with the toolpost collar for this purpose, and will shift the handle position by about a third of a turn. <br />
<br />
''ToDo: Make a taller nut of a similar pattern, to clear the height setting screws.''<br />
<br />
===Four Way Toolpost===<br />
The OEM four way toolpost is significantly more rigid than the quick change toolpost + holders because it has fewer and thicker parts and less overhang. Therefore the four way toolpost should be used when using carbide tooling. It requires shimming under the tool to set the tip height to the spindle center height - see below. The tool shanks are mostly significantly less than 15 mm wide, so need to be centered under its clamping screws, tempting as it is push the shank in for full side contact with the toolpost. If possible clamp the shank with all three screws not just two.<br />
<br />
==== Shimming ====<br />
We typically only mount up to two tools, and want maximum rigidity, so use 50 mm x 15 mm shims, (the full seat area), preferably with deburred edges and radiused corners so they aren't a hazard to the operator.<br />
<br />
We have pre-cut and marked shims of the following thicknesses: <br />
* 1x 3.23 mm, 2.42 mm, 1.56 mm, 0.32 mm, and 0.25 mm<br />
* 2x 1.00 mm, 0.77 mm, 0.12 mm, 0.11 mm, 0.10 mm and 0.05 mm<br />
* 4x 0.53 mm<br />
<br />
Our shims are mostly found materials (hence the awkward thicknesses) and are mostly a mixture of aluminium and steel, with a couple of GRP ones. The toolpost seat '''<u>must be absolutely clean</u>''' to avoid embedding debris in the aluminium or GRP shims, to get a consistent height and avoid tilting the tool - wipe it every time you change a tool! Put the thin shims at the bottom of the stack to avoid the tool shank edges creasing them. Shims are kept in a little yellow plastic box with a clear lid, near the carbide tools case.<br />
<br />
I made a tool height setting gauge (T shaped black acrylic with steps in its sides) which can be used to check the tool tip height matches the spindle center height using either the flat of the ways or the saddle as a reference. The tool tip should just fit under the lip of the appropriate step, with the T arms across the ways flats or on the saddle. It is kept in the box with the carbide insert tools.<br />
<br />
''ToDo:'' <br />
<br />
* ''Cut more shims neatly, mark them with their thickness.''<br />
* <s>''Do test cuts and start noting shim stack-ups for various tools.''</s><br />
* ''Organise shim storage!''<br />
<br />
=== HSS Tools ===<br />
[[File:Tool Bit Geometry.jpeg|thumb|Single point cutting tool geometry]]<br />
Our HSS tools are made from 8 mm square bar stock, hand-ground to tip profile in-house. See LittleMachineShop's [https://littlemachineshop.com/images/gallery/instructions/grindingtoolbits.pdf Grinding Tool Bits] notes. <br />
<br />
I've installed our usual HSS LH turning and parting off tools in two of the quick change holders and set the heights correctly. There are a couple of other HSS tools or tool blanks knocking about. Taking heavy cuts turning steel (even with good cutting oil) blunts HSS tools fairly quickly, which are time-consuming to re-sharpen nicely without a dedicated tool & cutter grinder with appropriate jigs. Its worth noting that the usual 'speeds & feeds' tables are commonly based on surface speeds expected to give a half hour (active cutting) tool life before resharpening.<br />
<br />
I touched up the LH turning tool by lapping on wet & dry (silicon carbide) paper on glass (Aka: [https://en.wikipedia.org/wiki/Scary_sharp 'Scary Sharp']) working upwards through the grits 200, 400, 600 and finally 1000, initially 'bluing' the surfaces to be lapped with a marker pen to see which areas needed taking down more. The end of the tool was significantly uneven so I touched that up freehand on the bench grinder to flatten it when it became apparent that 200 grit lapping wasn't cutting where it needed to. There was an existing micro-bevel on the leading side, which I kept. Finally I 'dubbed' the leading corner vertical edge on the 1000 grit to give it a very slight nose radius. A test cut on brass gave a very nice finish when turning.<br />
<br />
''Ian B has purchased some spare 8mm HSS tool blanks - talk to a lathe trainer if your proposed lathe work needs custom ground HSS tooling.'''<br />
<br />
=== Brazed Tungsten Carbide Tools ===<br />
Somewhat of a half-way house between hand ground HSS tooling and insert tooling with the disadvantages of both and some more besides - e.g. they are much harder to sharpen. So why do we bother? Some tool geometries would be awkward and tedious to hand grind, and Chinese import brazed carbide tooling is about half the price of similar HSS tooling, and far more readily available. Also, for space constrained tooling like boring bars, if you want carbide, for insert tooling, the size of the insert and its clamping seriously limits the minimum hole diameter you can work in. I have purchased a set of 3/8" shank brazed carbide tipped boring bars, but we currently cant sharpen them, due to lack of a diamond grinding wheel. <br />
<br />
=== Tungsten Carbide Insert Tools===<br />
Decoding ISO insert tooling part numbers: https://www.cutwel.co.uk/blog/learn-the-turning-tool-iso-code-system<br />
[[File:Carbide set.jpg|800px|thumb|left|Our set of Tungsten carbide insert lathe tools (before the new inserts were fitted)]]<br />
<br />
{| class=wikitable<br />
|+ Tools, left to right, (+ last across top):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| SSKCR0610H06 || 75° through boring || SCMT06204 || Long || 6 || 6.34 || ''4.33''<br />
|-<br />
| SSSCR0610H06 || 45° deep facing, internal chamfering || SCMT06204 || Long || 6 || 6.13 || ''4.58''<br />
|-<br />
| SWUCR0610H05 || 93° boring, deep facing || WCMT050308 || Long || 6 || 6.22 || ''4.48''<br />
|-<br />
| SWGCR0810E05 || 90° RH turning & facing || WCMT050308 || Short || 8 || 8.25 || '''2.45'''<br />
|-<br />
| SSSCR0610E06 || 45° turning, chamfering || SCMT06204 || Short || 8 || 8.75 || ''1.93''<br />
|-<br />
| SSBCR0610E06 || 75° RH turning, chamfering || SCMT06204 || Short || 8 || 8.72 || ''1.98''<br />
|-<br />
| LW0810R-04 || 60° external threading || JCL15-120 || Short || 8 || 7.44 * || ''3.28''<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || 8.23 || ''2.5 ?''<br />
|-<br />
| LN0813R-04 || 60° internal threading || JCL15-120 || Long || 7.95 || 7.44 * || ''3.28''<br />
|}<br />
<br />
{| class=wikitable<br />
|+ More Tools, (loose in tin):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || ~8.5 (not in use) ||<br />
|-<br />
| [https://www.glanze.co.uk/product/glanze-12-mm-60-degree-metric-internal-threading-tool/ Glanse SIR0012K11] || 60° internal threading bar || 11IRA60 || Long || 12 dia || ??? || ???<br />
|}<br />
''Shim stack heights in bold are tested, in italic are only calculated.'' ''Tip heights marked * are with new JCL15-120I inserts. The single remaining plain JCL15-120 insert has a slightly higher tip height.''<br />
<br />
Carbide tooling typically requires two to three times more speed than HSS and at least a couple of 'thou' depth of cut for best results.<br />
<br />
Chatter can rapidly kill carbide tooling by chipping the cutting edge. To improve rigidity and reduce the risk of chatter, the cross-slide and compound gib screws need to be well adjusted so there is minimal play in the slides, tool stick-out should be minimised, the four way toolpost should be kept over the cross-slide, and the work should be kept close to the chuck (or otherwise supported by tailstock or steady rest) to avoid excessive deflection.<br />
<br />
Thermal shock is almost instant death to carbide, and when dry cutting the insert tip can run very hot, so do not add extra cutting fluid manually during the cut. Pre-apply what you need, evenly, before starting the cut.<br />
<br />
Parting off or facing to center is high risk - if the tool tip is even slightly below center or if tool or work deflection takes it below center, the work will tend to climb over the tool tip as the cut approaches center, breaking the insert. To avoid this, the tool should be shimmed slightly above center, sufficient to allow for work and tool deflection, and unless very close to the chuck, a steady should be used. Its often preferable to part to a couple of mm dia. remaining then stop and saw through the remainder, then clean up by facing. Parting off hollow parts is much lower risk.<br />
<br />
Further investigation of the Tungsten carbide insert tool height situation is not encouraging - the so-called 'set' in question does not have a consistent tip height ''(see above table)''! In a real set, the insert seats *should* be machined allowing for the insert thickness to bring all the cutting edges to the same height with respect to the shank underside. However if you place them tip to tip on a table its easy to see there is considerable height variation, so they need to be individually shimmed (or at best, one machined shim will only be right for two or three tools). At this time we don't have dedicated shim stacks for each tool.<br />
<br />
A 2.42 mm thick shim brings the SWGCR0810E05 90° RH turning & facing tool almost exactly to center height, and good results were obtained turning 1" steel pipe. However facing 50mm steel bar stock to center found it to be slightly low, leaving a fractionally under 0.05 mm 'pip' so it needs another 0.03 mm to bring it fractionally above center. Fractionally too high is generally preferable to fractionally too low, due to tool deflection, so adding an 0.05 mm shim to the stack should produce optimum results.<br />
<br />
==== Inserts ====<br />
Ian B has purchased the spare inserts we needed in sets of five. He even was able to get the CK3 parting-off inserts which had been difficult to source!<br />
<br />
Inserts used in above tool set:<br />
* 3x SCMT06204 (square, indexable) https://www.rdgtools.co.uk/acatalog/SCMT-06-Carbide-Insert.html<br />
* 2x WCMT050308 (triangular, indexable) https://www.rdgtools.co.uk/acatalog/WCMT-05-T3-08-5XTIP-8813.html<br />
* 2x JCL15-120 (60 deg threading point) https://www.rdgtools.co.uk/acatalog/X5-JCL-15-120L-THREADING-TIPS-60-DEGREE--X5-TIP---23455.html<br />
* CK3 (parting off) https://www.rdgtools.co.uk/acatalog/CK3-CARBIDE-TIPS---PARTING--BOX-OF-5PCS--9437.html<br />
<br />
Inserts used in other tools:<br />
* 1x CK3 (as above) also missing from spare parting off tool<br />
* 1x 11IRA60 in Glanse threading bar + 1x spare<br />
<br />
=== Drills ===<br />
Various sizes of center drills are kept in a plastic bag next to the wooden accessories tray. There's also a small box of 2.5 mm center drills.<br />
<br />
We have a set of 11 TiN coated HSS drill bits from 1.5 to 8 mm, (in a cylindrical plastic index box) for tailstock drilling of brass, aluminium and non-abrasive plastics. To keep them sharp enough for the precision work we expect from the lathe, please don't use them for steel or reinforced plastics, and don't borrow them for non-lathe use. Metric and US [https://littlemachineshop.com/reference/numberdrillsize.php numbered]/[https://littlemachineshop.com/reference/letterdrillsize.php lettered] general use HSS drill bits are kept in two red metal index boxes next to the drill press.<br />
<br />
== Using the Lathe ==<br />
=== General ===<br />
Making dimensioned parts is primarily done by touching off the tool tip on a reference surface (with the lathe stopped, turning the chuck by hand), zeroing the handwheel dial, then manually counting turns and divisions. When backing off the tool its best to do so by exactly one whole turn so you don't forget the previous dial position. Stopping and measuring the work before taking the final cuts is essential if high accuracy is required. ''I've changed out the dial setscrews for flat tip ones with a tiny slug of solder under them so the dials are now friction fit on their shafts. i.e. if you hold the handle firmly taking up the backlash in the direction of cut, you can zero the dial just by grabbing and twisting it.''<br />
<br />
Carriage movement is less easy to measure as the handwheel is uncalibrated and advances an awkward bit over 19.2 mm per turn. Your options here when shoulders or other features must be exactly positioned are, in order of increasing accuracy: <br />
* Use measuring instruments, scribe the work at the desired length then work to the scribed line. Its often convenient to black the work with a permanent marker, then scribe with the tool tip, turning the chuck by hand.<br />
* for short distances, lock the carriage and use the compound, set parallel to the work<br />
* Set up a long travel dial indicator to measure carriage motion. <br />
N.B. with the leadscrew stopped, and the threading dial engaged, with its default 16 tooth gear, it will make one turn for every 24 mm of carriage movement (2 mm/div). This isn't accurate enough for positioning but is sufficient to check you aren't out by a whole mm or more.<br />
<br />
Do not allow any solvents to contact the chuck guard clear plastic as it will make the plastic brittle, or even craze it, and try to avoid melting it with the work light!<br />
<br />
===Speeds & Feeds===<br />
The surface speed of the tool relative to the work (or visa versa) is important, and best results will be achieved when it is in a tool type and material specific range. Because the surface speed is proportional to the diameter and the spindle RPM, it is usual to vary the spindle speed in inverse proportion to the diameter to get the surface speed in the desired range, and keep it there as the tool tip moves closer to the spindle axis. <br />
<br />
A cutting speed chart for HSS tooling, published by Model Engineer magazine can be found [https://www.model-engineer.co.uk/sites/7/documents/cutting%20speed%20chart.pdf [here<nowiki>]</nowiki>]. The second row is the target feed rate and the rest of the chart, apart from the diameter column is RPM.<br />
<br />
For carbide tooling cutting iron and steels, recommended speeds are generally three times higher than for HSS, but the CJ18A 2500 RPM max. spindle speed (in high gear) means you can only reach the optimum speed range for over 15 mm dia work. For small diameter work, HSS tooling may well be a better choice.<br />
<br />
An online metric speeds calculator is here: https://www.cgtk.co.uk/metalwork/calculators/cuttingspeeds <br />
<br />
How to do the maths to calculate speeds and feeds: https://www.cutwel.co.uk/blog/speeds-feeds-made-easy<br />
<br />
If you can hear the lathe 'sing' as it cuts, you are getting chatter, which invariably results in poor surface finish. Try decreasing (or possibly increasing) the spindle speed till the resonance stops. <br />
<br />
Once you have a wavy surface due to chatter, a light cut wont clean it up as the tool 'twangs' from peak to peak. You have to take a deep enough cut to get under it. For precision parts, its therefore desirable to take a trial finish cut while still 0.5 mm or so oversize, to give an opportunity to tweak the cut to get a good finish, check for taper, and that the part wont be undersize (on your test finish cut nominal diameter).<br />
<br />
=== Slide Locks ===<br />
* The carriage can be locked to the ways using the M5 hex screw through the top of the saddle to the left of the cross-slide. Double check the leadscrew is disengaged and the half-nuts open before locking it. Lock it when facing.<br />
* The cross slide can be locked by a M4 socket headed cap screw just in front of its middle gib screw. Locking the cross slide is helpful when turning very shallow conical features where the cross slide handle is in the way of the compound.<br />
* The compound slide can be locked by a M4 socket headed cap screw in line with the edge of the toolpost mount on the side with the gib adjustment screws. In normal use it should be kept backed off half a turn but it is desirable to tighten it for parting off operations to keep the resulting end faces flat.<br />
<br />
=== Compound ===<br />
The compound consists of a locking swivel and a top slide allowing cuts to be made at an angle to the axis e.g to produce bevelled or tapered features. There is a difference between US and UK usage, in the US a compound angle of 0° means the compound slide is parallel to the cross slide, but in the UK, 0° is parallel to the ways. The compound angle indicator on the CJ18A follows UK practice, 0° parallel to the ways, but it is not to be trusted, its out by a few degrees!<br />
<br />
One of the deficiencies of the CJ18A lathe is the difficulty of setting the compound angle. It is held and locked by two screws hidden under the top half of the compound slide, which must be wound back till its toolpost end is clear of the pivot point to access them. This may have to be repeated several times to snug them up enough to tap it to the desired angle, then finally tighten them. <br />
<br />
We generally keep the compound slide set approximately parallel to the ways so it can be used for short-distance longitudinal positioning without measuring. However it is unlikely to be closely parallel unless a test bar has been swept with a dial indicator on the slide, or test cuts made on a large OD workpiece and checked for taper.<br />
<br />
=== Chucks and Chuck Jaws ===<br />
==== Terminology ====<br />
* Inside jaws have steps on the outside to grip the ID of hollow work, but can also be used as outside jaws on small diameter parts (i.e. that fit through the spindle). <br />
* Outside jaws have steps on the inside to grip the OD of the work.<br />
* Universal chucks have a scroll plate with a spiral screw thread that moves all the jaws.<br />
* Independent chucks have individual adjusting screws for each jaw.<br />
<br />
==== The Chucks ====<br />
* The three jaw universal chuck can only grip near round or hexagonal work, which it centers, but its concentricity is not perfect so e.g. if you reverse the work and continue turning at the same diameter from the other end, you will see a line where the turned surfaces meet. It has separate sets of inside and outside jaws, and we normally keep the inside set installed to use as outside jaws for small diameter work.<br />
<br />
** Our jaws are individually numbered, stamped in the groove. They must be fitted in the correct sequence. The jaw slots are not clearly marked. Lowest runout for small dia. parts is achieved if you fit the jaws with #1 anticlockwise of the makers mark, then continue anticlockwise for #2 and #3.<br />
** A large strong rubber band is a great help getting all the jaws started on the scroll together - with slots #1 and #3 above the centerline and the scroll thread outer tip between #1 and #3, insert jaws #1 and #2 and put the rubber band round them to keep them in their slots. Insert jaw #3 and stretch the rubber band over it to hold it up into its slot. If the scroll was positioned correctly, all jaws should be at the same initial radius. The jaws can now be cranked in with the chuck key and they should all engage in step so they meet in the middle.<br />
:: ''Mini-lathe.com have the best instructions for [https://www.mini-lathe.com/mini_lathe/chucks/chucks.htm#Installing_Chuck_Jaws changing the jaws].'' <br />
<br />
* The four independent jaw chuck can grip most roundish or squarish work, which can either be carefully centered by the user, or deliberately gripped off-center. <br />
** Its jaws are reversible so can be swapped from inside to outside by simply cranking each jaw out and reinserting it the other way round, one at a time. DON'T move the jaws to different slots as they are likely to bind.<br />
** When setting up to face the sides of rectangular objects held crossways, it may be helpful to use both inside and outside jaw orientations, in symmetrical opposing pairs.<br />
** Its screws move their jaw 1/8" (3.125 mm) per turn<br />
<br />
* The jaws must '''never''' protrude from the chuck OD by more than one step, and for safety, its preferable they don't protrude at all, as they make the gap between the front of the bed and the chuck body an even more unforgiving meat grinder, and as the number of teeth engaged with the scroll or screw decreases, they loose strength, just when you need it the most to grip larger/heavier work. <br />
<br />
''Neither chuck is well suited to gripping tapered work safely. When seating work that doesn't quite fit through the chuck bore (which is larger than the 20mm spindle bore limit), be careful that it isn't seating on the chamfered edge of the chuck bore as it is far to easy to get the work slightly cocked so it doesn't run true.''<br />
<br />
==== Changing Chucks ====<br />
* When changing chucks, use the small grey plastic mat to protect the ways under the jaws in case you drop the chuck.<br />
* The spindle nose has two patterns of holes - the three hole pattern is for the three jaw chuck and the faceplate, and the four hole pattern is for the four jaw chuck. One hole is shared between the patterns, and is marked on the spindle nose.<br />
* To fit a chuck:<br />
** First check that the spindle nose and chuck back and recess are free of swarf, grit or other debris. Any foreign objects will tilt the chuck causing excessive runout and may mar the surfaces.<br />
** Remove the nuts and split lock washers from its studs, line its studs up with the hole pattern (preferably with the stud nearest anticlockwise to the makers mark through the marked spindle hole), fit and hold it in place with your right hand, and with your left, get the lock washer and nut on the top stud, and take up the slack.<br />
** One one nut is on, you no longer have to worry about dropping it, and can work round fitting the remaining washers and nuts, taking up the slack on each as you fit it. <br />
** Next, work round again getting them all finger tight, then tighten them gently, and finally work round fully tightening them. <br />
* Removal is the reverse of refitting. Put the washers and nuts back on the chuck's studs so they don't get lost.<br />
<br />
==== Gripping Threaded Work ====<br />
It is generally undesirable to chuck work gripped on a screw thread, as it is difficult to hold the work securely and get good concentricity while avoiding crushing the thread crests. However, if one must, one of the better ways of doing so is to wind a wire helix to fit the thread then clamp on the outside of the wire so it seats on the flanks of the thread. The wire should be mild steel or soft iron for steel parts and copper for aluminium and brass parts, single strand, round and of uniform diameter a little less than the thread pitch. It can be wound on the lathe, in reverse, by chucking a sacrificial mandrel of the same diameter and thread pitch, hooking the end of the wire round or under the jaw, against the direction of rotation, then holding the other end of the wire under tension with pliers and starting the lathe dead slow. Once wound and removed from the mandrel, the ends must be trimmed then it should be screwed on to the threaded work to provide a surface to chuck on.<br />
<br />
=== Faceplate Work ===<br />
Faceplate work is probably the most dangerous operation you can (or rather should) perform on a lathe. The working area is a large diameter spinning surface with protruding clamps to fixture the part that it is impractical to guard. Protruding clamps, studs, nuts etc. are very difficult to see at speed.<br />
<br />
'''Treat the faceplate with great respect and caution if you wish to continue to be able to count to ten on your fingers!''' <br />
<br />
The 65 mm cross-slide travel vs the 80 mm faceplate radius is a serious limitation that may require creative compound, toolpost and tool setups for larger parts, and doing full face cuts in two sections.<br />
<br />
''It is common practice to skim the faceplate to ensure it runs true. We have not (yet) done this, and wont till the spindle is in better bearings and the nose reground to minimise runout.''<br />
<br />
==== Clamping ====<br />
Open ended/sided clamps should be oriented so that cutting forces drive the work towards the clamping bolt/stud, not out from under the clamp. Minimize the protruding length of thread past the clamping nut, if necessary using sacrificial bolts or studs you can cut to length, or even using a long M8 stud for one of the faceplate mountings, so you can get a clamp nearer to the faceplate center. Double-check all clamps are secure, manually turn the faceplate to check the work and clamps clear the ways, top-slide and toolpost, and stand out of the 'line of fire' (a disc extending from the faceplate) when spinning up the work for the first time. <br />
<br />
If you need to machine close to a clamp, consider marking a safe limit circle on the faceplate and work with a marker pen to make it easier to see how close the cutting tool is to crash disaster. <br />
<br />
I strongly advise reading chapter two of Tubal Cain's book "Workholding in the Lathe" several times before your first faceplate setup, and if possible get another experienced lathe user to check your first few setups before spinning them up.<br />
<br />
==== Chuck Guard Removal ====<br />
The faceplate is too large diameter to fit under the chuck guard, but the guard has an interlock switch wqhich must be closed for the lathe to run. The guard is now fitted with wing nuts so it can be removed allowing the the interlock switch to close when using the faceplate. It *SHOULD* *ALWAYS* be refitted if a chuck is fitted, except when turning work too large to clear the guard. <br />
<br />
''The chuck guard is primarily there to make it very difficult to start the lathe without removing the chuck key and to reduce the area of large diameter spinning surface exposed. It may slow down the projectile if a chuck sheds a jaw but is unlikely to stop it. Also it serves to contain coolant spray spun off the chuck. As we don't use flood coolant this usually isn't an issue for us. As setting up for faceplate work doesn't use a chuck key, and the most hazardous zone is the face of the faceplate, with its spinning projecting clamps, with full access required for machining operations, which a guard would not cover, the consensus is that removing the guard is an acceptable risk.''<br />
<br />
=== Turning and Facing ===<br />
We are getting good results in aluminium, brass, and even steel using HSS cutting tools in quick-change tool holders, and the ~ 94 um/turn power feed. Unfortunately due to lack of rigidity in both the machine and smaller diameter parts, if you don't want the outer end to be over diameter, a light final cut and multiple 'spring' passes will probably be required.<br />
<br />
For aluminium, a sharp HSS tool and 0.5 mm (20 div) depth of cut gives good results with power feed for rapid stock removal. Its also easy maths as each cut takes ~ 1 mm off the diameter. Finish cuts should be much finer, 0.1 mm (4 div) is 'in the ballpark'.<br />
<br />
For steel, using carbide insert tooling, a 0.25 mm (10 div) depth of cut is more appropriate, and with pre-applied cutting oil, gives reasonable results with power feed if you use enough speed. The maths is not quite so easy as you are only taking 0.5 mm off the diameter per pass. Again, use finer finish cuts but try to plan your cuts so the final cut is still cutting, not smearing the surface!<br />
<br />
When facing or parting off, some skill is required to turn the cross-slide handwheel steadily to get a decent finish and to avoid shock-loading the tool tip. Increasing the spindle speed in one or more steps to keep up with the reducing diameter is advisable, but avoid speeds that cause resonances (resulting in chatter). When parting off, small through-hole parts may be caught on a thin rod chucked in the tailstock, and pre-positioned inside the work with its tip right up to the parting off position.<br />
<br />
==== Using the Steady Rests ====<br />
For the fixed steady rest, see Blondihacks' Lathe Skills #26 - How To Use a Steady Rest! [[#Youtube_Playlists_&_Videos|{below}]]<br />
<br />
Ours doesn't have ball bearing fingers, so a smooth surface on the work and adequate lubrication are essential. The thumbscrews can only tighten the fingers, so for small adjustments outwards you need to either slack off the clamping nuts or ease them slightly and use a drift against the back of the finger's slot. Once set, check the chuck still turns freely.<br />
<br />
The traveling steady rest needs to run on a machined surface, so at least for the first pass, must follow the tool, so its difficult to avoid using more compound slide overhang than is desirable. An initial surface should be cut next to the chuck or tailstock center before fitting the steady rest.<br />
<br />
Both are a PITA to fit - the fixed one has to have its clamping post inserted up through the bed, and the supplied spanner is useless near the headstock, and the travelling one's mounting holes on the saddle almost invariably need swarf picked out of them.<br />
<br />
==== Turning Between Centers ====<br />
<s>Using a MT3 to MT2 reducing sleeve, the MT2 dead center can be fitted in the spindle.</s> ''Currently the MT3 spindle taper is compromised.'' Alternatively, a soft center can be turned immediately before use in the three jaw chuck, but that must have its 60° point re-cut to concentric if the chuck is disturbed, and needs to be either large enough to bear on the chuck body, or must have a lip to bear on the end face of the jaws to take the axial thrust. Recutting the center is a PITA, as the compound angle must be set to 30° anticlockwise, then reset to a true 0° afterwards. Maybe a right-hand 30° end angle zero rake form tool is the answer, or use the carbide insert tool SSKCR0610H06 as a form tool with the toolpost rotated 15° anticlockwise.<br />
<br />
With the MT2 live center in the tailstock quill, this gives us a center either end of the work to hold it.<br />
<br />
We also need a drive dog similar to [https://littlemachineshop.com/products/product_view.php?ProductID=4473&category=1 this], and the corresponding drive post to bolt to the spindle nose. I have some 25mm bore thick wall iron pipe, which should do nicely. Lengths of the dog's straight tail and of the post TBD after I check how much the center protrudes. N.B. its recommended to tie the tail to the post to keep them in contact so they don't slam. ''Currently we will need to drive from the chuck jaws. Possibly use the exterior jaws with a short soft center gripped on the inside end and drive from the highest step.''<br />
<br />
=== Drilling ===<br />
Always start with a center drill so deflection of longer bits doesn't start the hole off-center. For larger bits (> 5 mm), first drill to the web size, then to final diameter. For a precision hole, drill slightly undersize and ream to final diameter. ''Supply your own reamers!''<br />
<br />
Caution: See note about the quill anti-rotation pin in section [[#Tailstock Quill|Tailstock Quill]] above.<br />
<br />
=== Boring ===<br />
Caution: As the spindle doesn't extend right through the headstock housing, if boring in a through hole, chips tend to fall out the back and tumble in the spindle bore till they fall into the change gears. To avoid this, one should plug the spindle bore with a wad of paper towel or rag and when cleaning up afterwards, use a rod to push it through towards the tailstock, with the chuck jaws (if fitted) wound clear of the spindle bore.<br />
<br />
A swivel bladed hole deburring tool (pale blue handle) can be found in the main room on the windowsill behind the drill press.<br />
<br />
A couple of boring jobs have been bodged with an awkwardly angled turning tool and achieving acceptable effective rake with enough clearance to reach deep enough into the hole has been problematic. I reviewed the tools we had and found none suitable for starting out in a 13mm bore, the max diameter we can (easily) drill. I therefore decided to buy a set of boring bars and make a holder for them. I had difficulty finding anything affordable under 10mm shank - the best low cost option was a [https://www.amazon.co.uk/dp/B07P5LGVBX set of nine 3/8" (9.525 mm) shank brazed carbide tipped boring bars], which would be close to the max capacity of the quick change boring bar holder - if we had one! Unfortunately this holder for our specific toolpost is difficult to find except in a toolpost bundle. Another annoyance is the variable tip height of the set, varying from 1.8 mm to 2.8 mm above the center of the shank.<br />
<br />
I therefore decided to make a boring bar holder of the [https://littlemachineshop.com/products/product_view.php?ProductID=1700 Littlemachineshop.com (USA) style] for use in the four way toolpost, as the additional rigidity will certainly help. Starting with a slightly over 50 mm length of 16 mm aluminium square bar and using the four jaw chuck , both ends were faced and an attempt was made to find its center and center drill it. It was then drilled out to ~9.8 mm after much drama due to blunt drills and drills that cut ~1mm oversize. Too big, but beggars cant be choosers as we didn't have a boring bar holder or a 3/8" reamer. Unfortunately the final hole ended up significantly off center. It was then chucked crossways and ~1 mm skimmed off its thickest side to gain clearance to allow it to be shimmed to height, then one side was slit lengthwise manually with a hacksaw.<br />
<br />
It was fitted to the for way toolpost and loaded with a booring bar, which clamped firmly. A 0.86 mm shim stack brought the tip of the largest boring bar almost spot on center height, with the difference easily accommodated by twisting the tool slightly. The three jaw chuck was then remounted, and a piece of iron pipe chucked for a test. It cuts well and leaves a decent surface finish.<br />
<br />
''The boring bar setup is a work in progress - talk to me before attempting to use them if you have a project that would benefit from boring..''<br />
<br />
ToDo: get something that can sharpen tools tipped with this grade of carbide - it needs some sort of diamond (or possibly CBN) wheel as green grit silicon carbide does little more than polish it. ''N.B. diamond wheels are rapidly eroded by grinding steel, so the supporting steel seat must be undercut with a regular grinding wheel before the diamond wheel can contact it.'' <br />
<br />
We'll also need 50 mm square sheet shims to fit under the toolpost to gain clearance in the toolpost above the tool or toolholder. A 2.4 mm shim would give us about the same above and below spindle center height, and we probably need a small selection of thinner ones.<br />
<br />
=== Thread Cutting ===<br />
The objective is to cut a thread that complies with the ISO metric thread profile. Our lathe is not currently equipped to cut non-metric threads, (with the exception of BA which have pitches based on metric threads of that era).<br />
<br />
[[File:ISO and UTS Thread Dimensions.svg|frame|center|Metric Thread Profile - from the geometry, H is ~86.6% of P]]<br />
<br />
Metric thread data - See 'Preferred Sizes' at: https://en.wikipedia.org/wiki/ISO_metric_screw_thread<br />
<br />
See "Mini Lathe User’s Guide" section '''Threading''' for general techniques *ONLY*, and above for change gears and threading dial setup.<br />
<br />
Amadeal specify the max. thread pitch as 2.5 mm. Any thread pitch greater than 1.5 nn requires the change gears to gear up. When gearing up it is desirable to distribute the ratio as evenly as possible over the two pairs of gears in the geartrain to avoid excessive tooth loading.<br />
<br />
==== External Threading ====<br />
Initially turn work to required Major Diameter, set up change gears and threading tool, touch off on the work, zero the top and cross slide dials, and do a 'scratch' pass to check the pitch. Back off the tool, return the carriage, and re-engage the half nuts on a valid dial line clear of the end of the thread then immediately stop the lathe, and hand turn the chuck till the tool tip is (hopefully) over the scratch to check the thread pickup. If all is good, return the carriage again, restart the lathe and start cutting your thread. <br />
<br />
Methods of doing so vary depending on the size of the thread and toughness of the metal, but straight-in plunge cutting is generally to be avoided as has the highest cutting forces, and does not reliably keep the carriage (and top-slide if set parallel to the work) loaded to avoid pitch errors due to backlash. <br />
<br />
If leaving the half-nuts engaged and reversing the lathe to return to the start of the thread for the next pass, its absolutely essential to back the tool out of the thread for the return pass as it will not follow the path of the cutting pass due to backlash in the geartrain, leadscrew mounts and half-nuts.<br />
<br />
==== Internal Threading ====<br />
''<nothing here yet>''<br />
<br />
== Cutting fluids ==<br />
=== Why bother? ===<br />
[https://youtu.be/mRuSYQ5Npek Watch this video] and contemplate what's actually happening to that thin ribbon of metal being removed. Most of the lathe's motor power is being turned into heat by internal friction in the chip being removed in the zone around the cutting edge, and surface friction at, and immediately behind the cutting edge, near-instantly heating the chip by up to several hundred degrees. Reducing the surface friction using a suitable cutting oil reduces the strain on the machine as a whole, and reduces workpiece and tool heating (and thus expansion) with consequent improvements in maximum usable feed and depth of cut, surface finish and accuracy. It also drastically increases the life of the cutting edge.<br />
<br />
=== Practicalities === <br />
We don't have a coolant system for the lathe and *really* don't want the maintenance hassles of using soluble cutting oil/coolant as if used infrequently its a PITA to keep recirculated high water content cutting fluids from going rancid and stinky, and they can also rust the ways, so even a total loss gravity feed system is problematic. Therefore if dry machining doesn't give a good enough finish, we tend to use oil applied topically, by hand to the work. <br />
<br />
* Hard brass is typically free-turning without oil, however some light oil for the final cut can improve surface finish, but with the disadvantage that it will increase loose chip buildup on the tool as hard brass typically forms short spalls or splinters rather than curly chips.<br />
<br />
* Many Aluminium alloys tend to be gummy, and Paraffin or other mineral spirits mixed with a little oil can help prevent the aluminum welding to the tool edge. WD40 will do at a pinch, but its messy to apply from a spray can.<br />
<br />
* Steel really needs *GOOD* cutting oil. Lard oil is the traditional choice for steel. If there are any objections to lard oil, we should bite the bullet and get some commercial dark high Sulphur cutting oil, but beware, many such oils use an additive package that includes lard oil.<br />
* Cast iron (except ductile) should be cut dry, as the carbon micro-inclusions self-lubricate it, and the carbide in the dust (primarily Cementite) are very abrasive, so tend to form a grinding compound if mixed with oil. <br />
<br />
I've sorted out an oil pot lid with a 1/2" brass collar soldered in to give a nice smooth sided hole, for ease of use and to minimize the risk of spills when using a brush to apply cutting oils, and got some dirt-cheap brushes. It fits Shippam's paste (and similar own-brand spread) jars and I've found several jars and ordinary lids to seal them for storage. Unfortunately it isn't the easiest to get this type of jars' lids back on square so they seal properly, and if you over-tighten them and there's a temperature change, they can be a total <expletive> to reopen. Using the rubberised handles of a large pair of pliers to grip the jar lid just above its rim is the best option, and avoids damaging the lids.<br />
<br />
''N.B. For the smaller brushes, the glue holding the bristles in is attacked by paraffin. To prevent loss of bristles, crimp the aluminium ferrule of each new brush of this type before use.''<br />
<br />
We have, in labelled jars:<br />
<br />
* Sulphurised Lard oil thinned with paraffin. Best choice for heavy cuts and threading in steel but stinky.<br />
* Lard oil thinned with paraffin. Good for steel and acceptable for softer copper alloys<br />
* Paraffin with a trace of light oil. Good for aluminium, and can help prevent squealing chatter on finish cuts in brass.<br />
<br />
I've also got some paraffin wax (in the form of a stubby candle), which can be applied lightly (under power) to brass and aluminium stock especially on the finish pass. It makes less mess than oil but unfortunately tends to build up on the tool tip, making it difficult to 'work by eye' without frequent pauses to clean the tool tip.<br />
<br />
We've also got a tin of [https://www.rocol.com/products/rtd-compound Rocol RTD cutting compound], which is a thick paste. Its highly recommended for drilling and tapping steel (in the drill press or by hand), but as a paste, is less useful for general lathe work unless thinned to a fluid consistency, e.g. with paraffin or white spirits. OTOH its certainly worth trying for high speed facing steel as it is less likely to get flung off.<br />
<br />
== Cleaning and Maintenance ==<br />
Swarf is a significant cut hazard to the operator, especially stringy swarf from cutting steel. Never touch it bare-handed - always use a tool e.g. a brush, or a hook, or needle nose pliers for grabbing long swarf.<br />
<br />
* After use, brush all swarf off the toolholder, compound and cross slide etc. ways and leadscrew. Ian B has blocked off the opening at the headstock end of the rear splashguard (to try to keep swarf out of the motor), so one must sweep the swarf towards the open tailstock end and catch it in a dustpan or similar. Preferably, also thoroughly clean out the chip tray under the lathe, but at least sweep out visible swarf.<br />
* Wipe up any cutting fluid residue and re-lubricate affected sliding surfaces with way oil.<br />
* Do not solvent clean the chuck guard, as it will make the plastic brittle, or even craze it. Water with a little detergent is permissible for cleaning it, with the guard totally removed from the lathe.<br />
<br />
Before engaging the half-nuts for power feed/threading, check the leadscrew is clean! ''Best cleaned under power, with a toothbrush.'' <br />
<br />
'''Caution:''' The traverse gears behind the carriage handwheel are in an open-backed housing and tend to become packed with swarf! Swarf buildup here will result in jerky carriage movement. Clean out as much as you can with a toothbrush ...<br />
<br />
===Lack of lubrication and/or swarf or dirt build-up can be disastrous===<br />
* If using the change gears/power feed, lack of lubrication of the B-C stub shaft center pin or either leadscrew end bearing can result in seizure and immediate destruction of one or more gears in the gear train or worse. <br />
* Small pieces of swarf can get between the saddle and ways, or into the slides degrading accuracy, possibly permanently if hard swarf scores them, or jamming them. The carriage handwheel gears behind the apron are notorious for accumulating swarf, and swarf buildup on the leadscrew can prevent the half-nuts engaging properly, resulting in scrapped work, and possibly stripped half-nuts. <br />
* Metal swarf can get into the motor (''though Ian B has modified the rear chip catcher to reduce the risk)'' or into the control box via the leadscrew, and short-circuit stuff. At best it will blow the fuse and need a strip-down to clean it out, at worst it may require a replacement [https://www.amadeal.co.uk/acatalog/Speed-Control-Circuit-Board--12amp-AMA_SP_CJ18_SCB12.html#SID=12 speed controller] ''(currently £96)'' and/or [https://www.amadeal.co.uk/acatalog/550W-motor-for-CJ18A-Mini-Lathe-467.html#SID=240 motor] ''(currently £105)'' and possibly other electrical parts. We should probably fit a [https://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C3-Mini-Lathe-Spares/C3-256-Leadscrew-Grommet-Dustproof-Cover C3-256 Leadscrew Grommet] to keep swarf out of the control box, as it tends to drop onto the 'Filter' board which is mounted horizontally, below the leadscrew.<br />
* Grit from grinding, sanding etc. forms a grinding paste with the way oil, and will rapidly wear out the ways, saddle and slides. Keep grit off at all costs e.g. by covering the ways and slides during grinding/sanding operations, and if there's any chance grit has gotten where it shouldn't, clean and re-lubricate *BEFORE* moving the carriage or slides, then move the carriage and slides, wipe down where they were with a clean paper towel and check there's no remaining traces of dirt other than clean way oil on the paper towel. If it doesn't come clean when you re-lubricate and move it again, a full strip down may be required to solvent clean and relubricate the precision sliding surfaces.<br />
* Although a metalworking lathe *can* be used to turn hardwood, wood dust and small chips are extremely pernicious, as they get everywhere, even clinging to clean surfaces, are abrasive due to their silica content, and are hygroscopic, promoting rust. An even more thorough clean-up than after using abrasives is needed, immediately afterwards. Oily wood dust and fine wood chips in significant quantities are a fire hazard, even in the trash bin.<br />
<br />
===Lubrication===<br />
See section: "Lubrication" in LittleMachineShop.com "Mini Lathe User’s Guide" [[Ian_M's_Lathe_Notes#Manuals|(below)]]. As we usually only open two nights a week, in the table on page 16, Daily lubrication becomes Weekly and Weekly becomes Monthly.<br />
<br />
===General Maintenance===<br />
* The grubscrews holding the cross-slide and compound slide dials tend to loosen due to vibration and use of the dials. Keep them snugged up, but not so tight the dials cant be set without an Allen key.<br />
<br />
* The screws holding the cross-slide nut tend to work loose due to vibration. Crank the handle to and fro through the backlash and visually check there is no movement of the screw heads in their holes. If there is, see the [[#Excessive_cross-slide_backlash|notes below]].<br />
<br />
===Removing the Carriage===<br />
Its possible to remove the carriage from the bed for cleaning etc. without dismantling it. The only stop to its motion is the righthand leadscrew bearing.<br />
<br />
Start by removing the tailstock. Crank the carriage to the tailstock end then remove the leadscrew bearing (two screws and a nyloc nut on the leadscrew end). With the half-nuts open, hold the leadscrew centered in them and crank the carriage off the end of its rack, then slide it off the end of the bed.<br />
<br />
Refitting is the reverse of removal, except (if its gibs are correctly adjusted) the carriage will be very tight on the end of the bed ways so may be difficult to work onto the ways without a stack of blocks of wood or similar to support it at exactly the right height. The righthand leadscrew bearing must be refitted with the carriage as close as possible to it and the half-nuts firmly closed to support the leadscrew at the correct height to hold it in alignment while the screws are being tightened. The nyloc nut controls leadscrew end-play. Fully tighten it then back it off slightly till the leadscrew turns freely with its change gear removed.<br />
<br />
If the Apron has been off, refit it with the screws no more than lightly finger tight and only finally tighten them after checking lead screw engagement at both ends of the carriage travel and that the rack and pinion operates smoothly over the full travel.<br />
<br />
== Issues and Annoyances ==<br />
As of September 2023 - mostly resolved, apart from the spindle bearings and runout, the lathe is in better condition than it has been for a number of years.<br />
<br />
===Four Jaw Chuck has two jaws too tight===<br />
Fixed 27/10/2023: Two of the chuck jaws were tight in their slots, making precise adjustment difficult due to lack of 'feel'. Moving the jaws round the slots showed the problem mostly followed the jaw not the slot. The grooves in the opposite sides of the affected jaws that run in the chuck slots were slightly out of true, and the rails either side of the slots were slightly too thick towards the center. Due to the difficulty of seeing the high spots, after cleaning up and deburring the jaws didn't do enough to ease them, I decided to grind the top of the rails where they were binding. Several repetitions of spotting with Engineer's blue, grinding, then diamond filing the high spots has eased them enough. I cleaned everything, greased the jaw slides and screws, and refitted the studs so the chuck is now fit for service.<br />
<br />
''N.B. Don't move the jaws to a different slot - the formerly tight jaws *must* stay in the slots furthest from the makers mark.''<br />
<br />
===Excessive Runout===<br />
Mostly fixed 24/10/2022: I ground the chuck seating surface of the spindle nose (outside lip) to under half a thou runout. This also cleaned up several burrs. It would be possible to do better, but that would need good spindle bearings, and a more rigid toolpost grinder mount.<br />
<br />
Our spindle nose was damaged years ago by a person with little mechanical aptitude (who shall remain nameless) beating it up with a hammer mushrooming the spindle nose. We are getting several thousandths runout at the end of the MT3 bore, a MT3 to MT2 reducer sleeve in it runs visibly out of true, as does the spindle nose flange. When you put a chuck on it, the runout is magnified by the distance from the spindle nose. Ideally we would replace the spindle when we change the bearings but its £52 [https://www.amadeal.co.uk/acatalog/4-Spindle-Upgrade-Real-Bull-Mini-lathe-CJ18-series-AMA_SP_CJ18_003RB.html#SID=9 from Amadeal] and money is tight. It may well require more work after the bearing upgrade. Once good bearings are in, if we can borrow a decent MT3 arbour as a reference, we should consider skimming the bore.<br />
<br />
===Spindle bearings===<br />
* The spindle bearings appear to be close to worn out. They are notably noisy when running, and there appears to be more slop in the spindle than is desirable. There is notable resonance around 600 RPM, and surface finish of end faces is often poor. We have some ideas for possible replacement/upgrade, but it requires a major teardown.<br />
<br />
: The original bearings are allegedly 6206-2RS or 6206-ZZ deep groove ball bearings - 2RS codes rubber seals both sides and ZZ codes metal shields. Although the deep groove gives reasonable ability to withstand axial loads, the bearing balls point contact means they are vulnerable to [https://en.wikipedia.org/wiki/Brinelling brinelling] due to shock loading. The jammed on three jaw chuck didn't help this, as before we skimmed the spindle nose lip, it had to be driven off using a bar through the spindle bore, shock loading the bearings every time. Also even a minor 'crash' could have brinelled them due to eccentric shock loading, and the lathe has previously been crashed badly enough to need drive gear replacement. There are also issues with the 'approved' method of spindle and bearing removal from the headstock brinelling them, even if you don't abuse the spindle nose with a hammer!<br />
<br />
: A possible replacement is 30206 tapered roller bearings. The new bearings are slightly thicker so the plastic spindle spacer (15) needs to be machined to length to get the 45 tooth spur gear that drives the change gears laterally aligned with the tumbler gears. If a temporary replacement (3D printed?) is fitted, the lathe can be run (without power feed capability) so this can be done on the lathe after fitting the new bearings. As tapered roller bearings have line contact, they are significantly more resistant to brinelling.<br />
<br />
: ''See [[Talk:Ian_M%27s_Lathe_Notes]] for notes, links etc. for this upgrade.''<br />
<br />
===Motor stuttering===<br />
* Fixed 21/09/2023: The motor was running very erratically and it was very difficult to set a speed. Several loose connections were found in the control box, mostly loose female spades to the motor controller board, but also a dry jointed braking resistor on the 'Filter' board, and an inhibit wire completely off its terminal on the forward/reverse switch, making intermittent contact. After tightening and/or remaking all affected connections, it was much improved but still not right below 300 RPM. The remaining issues were due to poor wiper contact in the speed control pot, and stripping it, cleaning the track and contact ring and re-tensioning the contacts resulted in the motor now running smoothly over the full speed range. The speed is slow to settle, and while part of that is probably the lag in the digital tach, I suspect that the KBIC motor speed controller isn't properly tuned as it was (allegedly) previously replaced.<br />
<br />
===Drive belt slipping===<br />
* Fixed 28/9/2022: During testing the motor after the above issue, it was noted that the chuck could be stalled, slipping the drive belt, with not much torque. The drive belt was determined to be loose and a bit worn, but still in acceptable condition. <br />
<br />
: Access for servicing the belt requires removing the control box ''(2 spades to ZVR switch disconnect the supply, speed sensor and motor simply unplug from the 'filter board')'', the motor cover, chuck guard switch assembly + wiring cover, the change gear 'A' (drive) shaft carrier assembly, and the tumbler gear assembly. See https://youtu.be/EkxlIz01BdA for disassembly/reassembly, though on our lathe, the speed encoder ring on the spindle prevents the belt cover from being fully removed without disturbing the spindle nuts. There is enough room to work with it loose, but still trapped by the encoder ring. Also, unlike the video, if the 'jack' screws under the headstock are correctly adjusted, and the studs aren't excessively bent, there is no need to make custom studs. <br />
<br />
: It turns out that our lathe was missing the M6 hex headed jack screws that press the motor down to resist the belt tension, and the motor had cocked out of position at a severe angle. I know Ian B had had considerable trouble adjusting it after the motor fault back in October 2022, and I believe it had been getting slowly worse ever since. The jack screws were probably mistaken for headstock fixing bolts during disassembly after the crash that resulted in the metal Hi/Lo gears being fitted, then lost. The penny washers on the studs had dished, so I turned them over and backed them up with smaller washers and switched to Nyloc nuts so they cant back off due to vibration. N.B. There is a packing washer on the motor side on one of the studs, presumably so the shaft is true to the ways. Adjusting the motor is awkward to say the least. One has to slack the stud nuts off a lot, pry under its rear end to lift it enough to be parallel to the ways, snug the stud nuts, check alignment, then set the jack screws and their lock nuts to hold it there, and finally tighten the stud nuts. <br />
<br />
: Tension: According to Sieg, it should be possible to twist the belt 90° mid span with a light finger grip. Other sources say 1/32" - 3/32" deflection mid span with light finger pressure.<br />
<br />
===Speed display blanking===<br />
* The speed display has been intermittent, blanking and flashing 8888 and 0 at certain speeds for as long as I have been using the lathe. Finally on 18/07/2022 it failed completely, with no display. I removed the display module and bench tested it - the pins are labelled 5V GND PL PE, PE is frame ground and PL is a TTL level pulse from the speed sensor - confirming that it was in good working order. My suspicions then turned to its power supply on the 'Filter' board. With both the sensor and display unplugged, the 5V rail was found to have a only a couple of volts, but the unreg DC was 17V and stable. Replacing the 78L05 5V regulator restored the 5V rail and normal operation.<br />
<br />
: ''I conclude its been failing for a while with high load current due to speeds with more lit segments causing it to drop out, resetting the speed display, causing it to blank, lowering the current enough for the regulator to recover, then the display MCU lamp tests (8888) then re-acquires the speed, repeating ad-nauseum till the speed is changed. I don't like the design as the high input voltage results in excessive dissipation.'' <br />
<br />
: ''ToDo: If it fails again, bench test display to measure its worst case current consumption, then fit an appropriate dropper resistor to reduce the 78L05 dissipation.''<br />
<br />
===Quill spinning when drilling===<br />
* The quill was tending to spin while drilling because its anti-rotation pin (a M5 dog tip setscrew) was sheered. I've removed the debris, aligned the scale with the top of the tailstock and fitted a longer M5 dog-tip setscrew to replace it, with a nut to lock it at the correct height. N.B. the pin isn't that 'meaty' so if using big drills in tough metals, to prevent shearing it, it should be backed out so the quill can be turned by hand and unwanted rotation controlled by being quick with the quill lock if it starts to spin, or even using a close fitting rod in one of the chuck key holes with plastic tube over it to protect the ways. <br />
: ''If the screw sheers again, the quill will need to be removed and the tailstock taken off the lathe so the sheered tip can be shaken out, and if the setscrew is difficult to remove it probably means the threads are mangled where it sheered. Try driving it right through with the quill out.''<br />
<br />
===Sloppy quick change toolpost locking mechanism===<br />
* Once the dovetail clamp screw was slackened, there was nothing preventing the dovetail twisting or cocking significantly, and friction with the toolholder made it tend to do so, making toolholder insertion and removal more difficult unless the clamping screw was backed off excessively. I added a compression spring around the clamp screw inside the toolpost to push the dovetail outwards so it mostly retains alignment when open, allowing toolholders to slide on or off cleanly with far less screw slackening.<br />
<br />
===Leadscrew rubbing===<br />
* The leadscrew shaft is rubbing on the insulating separator inside the control box. Unfortunately the corner of the relay on the Filter Control Board (#160) doesn't allow enough clearance. Although the friction isn't much of a problem at high reduction ratios, e.g. 16:1 power feed, it increases the stress on the change gear train, and may be problematic when threading at feeds above 1:1. ''Possibly pack out the control box mountings by a couple of mm.'' <br />
<br />
===High/Low lever backwards!===<br />
* The high-low drive gear selector behind the headstock is incorrectly labelled and differs from the manual: low gear (which we normally use) is with the lever towards the tailstock. ''I suspect that the gears in the headstock were refitted the wrong way round when it was upgraded to metal gears.''<br />
<br />
: ''ToDo: Get it reassembled the right way round during the spindle bearing upgrade!''<br />
<br />
===Carriage lock fouls top slide===<br />
* The T handscrew has been replaced with a M5 hex headed bolt, to permit access when the top slide is over it. An 1/4" drive 8mm socket is usually left on it, but needs to be removed when the full cross slide travel is needed. The small (4 jaw) chuck key is near enough 1/4" to use for it. If you need to (un)lock it while the compound is over it, you'll need an 8mm spanner. ''The [https://www.amadeal.co.uk/acatalog/Mini-Lathe-Carriage-Lock-463.html Amadeal lock screw] is in the spares tin as it was too high and fouled the compound slide.''<br />
<br />
===Tailstock locking lever loose===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock - See full image for key to screws]]<br />
* Diagnosed and fixed 10/1/2023 - In the base of the upper section of the tailstock, there are two dog tip set screws that engage with locating grooves in the counter-rotating shafts carrying the eccentric locking cams. They'd backed off, probably due to vibration. They need to be tightened till they bottom out in the groove, making sure they are '''in''' the groove, backed off half a turn so the shafts can turn easily, and locked in place. There's no facility to do so, so reassemble with weak threadlocker. Unfortunately to get to them you have to remove the tailstock base slide, which is held on by the pressure of four adjusting grub screws, which all need backing off, and one socket headed bolt from underneath so full tailstock realignment is required after reassembly, which even for a rough alignment is tedious.<br />
: <s>The tailstock locking lever is loose and can be pulled out on its axis. It works OK when fully pushed home but needs investigating. ''I tightened the grub screw as the lever was coming off its shaft, but the whole shaft pushes/pulls in and out. It works OK fully pushed in, but it seems something that is meant to retain it has failed inside the tailstock base.</s><br />
<br />
===Gear alignment issues===<br />
* Change gear alignment is poor. I've currently got a gapped washer (to clear the key) packing out the A shaft so the gears line up, but this reduces the key's engagement so is problematic due to the high loading if the gears are set up for coarser threads. <s>Also I need to turn down some penny washers to slightly less than the root diameter of the metal 20T pinions, as gear retaining washers.</s> ''The gear retaining washers for A gear and B-C stub shaft are now done, turned down to slightly under 16 mm dia. Spares in the change gear tin. ToDo: The D (leadscrew) washer requires a larger center hole, so make two more with that hole.'' <br />
<br />
===Saddle gibs loose===<br />
* Fixed 11/04/2023: I took the apron off for access (and to clean the carriage handwheel gears), and found the front sheer plate screws were completely loose. I've snugged them up some and set the opposing grub screws and got a lot of the slop out. I've re-checked the front ones, and taken up the slop in the rear ones - Unfortunately it wasn't possible to get carriage movement to have an even 'feel' over its whole travel, and its noticeably tighter near the tailstock. If light hand pressure on the side of the unlocked carriage can cause movement (with the half-nuts open), its time to readjust them again, though it should be possible to move the carriage with a firm push. <s>The saddle gibs (actually the sheer plates) were too loose, to the point that engaging a slightly stiff threading dial could cause it to self-feed, an obvious crash hazard if working near the chuck or a step in the work.</s><br />
<br />
''N.B. the lefthand front opposing grubscrew is short, (fully recessed) and unlike the others does *NOT* have a locking nut as it must clear the traverse pinion. A wrap of PTFE tape provides enough friction to keep it in place, though possibly a bit of nylon fishing line down its hole would be better.''<br />
<br />
===Excessive cross-slide backlash===<br />
* ''Fixed 21/11/2023.'' Originally, back in October 2023, The cross-slide screw had excessive backlash (nearly three turns), which increases the risk of loosing track of the cut depth when cutting steps, and during threading operations. If you ended up off by a turn too far in, a crash would be the most likely outcome.<br />
: The original excessive backlash was traced to loose cross-slide screw nut mountings. The nut has two socket headed cap screws pulling up, one either end, accessible from the top of the cross-slide, which control the tilt of the nut to take up backlash in the nut, and an opposing grub screw pressing down on the center of the nut to make it longitudinally rigid. Snugging up the grub screw reduced the backlash to 10 divisions or so, or 0.25 mm. A year later, the backlash had increased to one turn due to the cross-slide nut mounting screws working loose again.<br />
<br />
: 07/11/2023: I investigated further: It is difficult to get the cross-slide nut aligned correctly as it must be at the same height as the screw which is constrained by the bearing surfaces in the bracket. With the cross-slide almost at the front limit of its travel, I removed the screw and set the nut as level as possible and visually centered in the bore, then re-fitted the bracket and screw, then adjusted the tilt till it turned freely through the backlash. I then tilted it up at the front till some drag was felt to minimise the backlash and tightened the screws to lock it in place balancing them to maintain the same feel as I tightened them. The result was 7 divisions of backlash, acceptable but not great. During normal turning operations, the load on the nut is tension on the front screw and pressure on the grubscrew, so if it slackens again due to vibration from chatter, odds are it will be the rear screw that's loosened.<br />
<br />
: 16/11/2023 - 21/11/2023: The backlash had crept back up to 11 divisions (0.275 mm). We don't have any >14 mm brass stock (or even near that) so I tried making the shim washer out of aluminium. I was shooting for 0.24 mm but due to poor technique got 0.28 mm. No good - locked solid. I lapped it down and tried it till I got it down to 0.20 mm which gave about 3 divisions backlash - good enough, but the screw was too tight due to the shim washer not being bevelled at its outer edge resulting in it cupping in its seat. Filing a bevel round the OD and re-lapping it resulted in a 3 - 4 divisions of backlash. Its a little mushy due to the washer having been kinked removing it, so ideally a new (brass) washer should be made. <br />
<br />
* Further reduction of backlash: https://youtu.be/Wu_tI29JL2Y?t=163 <br />
: Brass tinned with Pb-free solder to form a white metal bearing surface should work at least as well as the bronze used in the video. The shim washer needs to be 10.2mm ID, with a full thickness bevel on a 14 mm OD. It isn't necessary to remove the lead screw from the cross slide, as the washer can be fitted in-situ with only the bracket removed.<br />
<br />
===3 Jaw chuck didn't mount properly===<br />
* Fixed 7/4/2023 by grinding the spindle nose lip. The three jaw chuck can now be installed and removed by hand with no hammering. A test bar in it now has only 2 thou runout (TIR) at the chuck.<br />
: <s>The three jaw chuck and the faceplate aren't seating properly on the spindle nose. Its too tight on the register diameter of the lip. This results in grossly excessive runout, and also makes this chuck and the faceplate a PITA to fit or remove.</s><br />
: ''The spindle nose had been abused with a hammer (before my time) which mushroomed it and may have brinelled its bearings. See '''Excessive Runout''' and '''Spindle bearings''' above.''<br />
<br />
== Manuals, Books and other resources ==<br />
=== Manuals ===<br />
The [https://wiki.richmondmakerlabs.uk/images/a/a3/Lathe_InductionNotes.pdf RML CJ18A Mini-Lathe Induction Notes]. Your mandatory Lathe Induction will cover most of this but its good to be able to refer back to it.<br />
<br />
Official [https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Amadeal CJ18A Manual], or paper copy (less complete) kept on shelf above lathe.<br />
<br />
The [https://www.chesterhobbystore.com/wp-content/uploads/2022/11/Conquest-Super-Lathe.pdf Conquest Super Lathe manual] is considerably better than the Amadeal manual and is for a near-identical machine.<br />
<br />
The [https://littlemachineshop.com/images/gallery/info/minilatheusersguide.pdf Mini Lathe User’s Guide] from LittleMachineShop.com is even more comprehensive, going into its usage in some detail, with a proper TOC, and covers both US and Metric versions of Realbull Mini-lathes. ''The only fly in the ointment is the threading section assumes a US lead screw so change gear selections and threading dial divisions will not be correct for our lathe.''<br />
<br />
[https://www.arceurotrade.co.uk/machineguides/C3-Mini-Lathe-Dismantling-and-Reassembly-Guide.pdf Sieg C3 Mini-lathe Dismantling and Reassembly Guide] "A picture story book to help you dismantle and reassemble your Sieg C3 Mini-Lathe" ''It is similar enough to ours to serve as a maintenance guide, except for the electronics, spindle drive and other headstock innards.<br />
<br />
The motor controller is a clone of a [https://acim.nidec.com/drives/kbelectronics/-/media/kbelectronics/documents/dc-drives/manuals/kbic_manual.ashx?la=en KBIC® SCR DC Motor Speed Control]<br />
<br />
=== Books ===<br />
'''Metal Turning on the Lathe''', by David A Clark, Crowood Metalworking Guides, ISBN-13: 978-1847975232 [https://www.amazon.co.uk/gp/product/B00E78RKIG Kindle Edition (£8.99)]. ''A 'free' epub can be googled for, *NOT* linked here due to dubious legality.''<br />
<br />
'''[https://archive.org/details/03screwcuttinginthelathe Screwcutting In The Lathe]''', by Martin Cleeve (a pen-name of Kenneth C Hart), Workshop Practice series #3, ISBN-13: 9780852428382<br />
<br />
'''[https://archive.org/details/15workholdinginthelathe Workholding in the Lathe]''', by 'Tubal Cain' (a pen-name of Tom Walsh), Workshop Practice series #15, Argus Books, ISBN-10: 0852429088<br />
<br />
'''[https://archive.org/details/20metalworkandmachininghintsandtips Metalwork and Machining Hints and Tips]''', by Ian Bradley, Workshop Practice series #20, ISBN-13: 9780852429471<br />
<br />
'''[https://archive.org/details/38toolandcuttersharpening Tool and Cutter Sharpening]''', by Harold Hall, Workshop Practice series #38, ISBN-13: 9781854862419<br />
<br />
'''[https://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpaperT204.pdf Cutting Fluids]''', by EC Bingham, NIST Tech. Paper No. 204, 1921<br />
<br />
=== WWW resources ===<br />
==== Mini-lathe Specific ====<br />
There's a *LOT* of mini-lathe info online. Notable sites include:<br />
* http://www.mini-lathe.com/ - A major Realbull/Sieg mini-lathe resource.<br />
* http://mikesworkshop.weebly.com/lathe-modifications.html - many mods including carriage DRO autostop, and variable speed leadscrew motor drive, cross-slide motor drive, etc. He also has a page with a bunch of accessories, toolholders etc. - http://mikesworkshop.weebly.com/lathe-accessories-and-tooling.html<br />
* http://andysmachines.weebly.com/variable-speed-controls.html - Scroll down to the 'UPDATE' section for the schematic of a very similar SCR speed control board. It also has the schematic for an earlier version of the Auxiliary Control Board (aka: 'Filter' board).<br />
<br />
==== Forums ====<br />
''with publicly accessible archives''<br />
* https://groups.io/g/7x12MiniLathe - Mini-lathe specific, active<br />
* https://www.hobby-machinist.com/forums/mini-lathe-mini-mill-information.220/ - active<br />
==== Youtube Playlists & Videos ====<br />
* Blondihacks: [https://www.youtube.com/playlist?list=PLY67-4BrEae9Ad91LPRIhcLJM9fO-HJyN Lathe Skills] (playlist) - "This is an educational series to help you learn to use your metal lathe. Watch them in order for best results! Satisfaction not guaranteed, especially if you're a cranky sort of person."<br />
* Frank Hoose (Minilathe.com) has a couple of relevant Youtube playlists:<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn7ON0jGM5UbM-KZDT56MOIp Mini Lathe Operations]<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn4nGRZaVq3wTOlvZNOmdAZ2 Mini Lathe Overview]<br />
<br />
==== General Machining ====<br />
* https://www.machiningdoctor.com/ - "THE #1 MACHINING TECHNICAL HUB"<br />
<br />
==Projects==<br />
[[File:VESA mount.jpg|thumb|Machined VESA mounting plate (left) and plate from Dell monitor stand it must match (right). The translucent washer shows the size of the original center hole.]]<br />
* My first faceplate project was boring out the center hole in a VESA mounting plate to adapt it to fit onto a surplus Dell 1708FP monitor stand. The part was centered using the tailstock dead center engaging with its original center hole. I clamped the part with studs and penny washers on the driving side of two opposite corners, with cap screws in the next slot round to trap the corners under the clamping washers, then withdrew the tailstock and dead center. After machining out the bore, I used the tip of the tool, rotating the chuck by hand, to scribe a circle for laying out the bolt holes. I finished off laying out and drilling the bolt and locating holes by hand at home, fitted it to the stand, and mounted the 2nd hand LG 24" widescreen monitor.<br />
<br />
* Another ultimately unsuccessful project was fly cutting aluminum flat bar to thickness to make custom shims for the set of carbide insert tools, for the four way toolpost. The 8 mm shank tools need ~2.5 mm shim stacks, and the 6 mm shank tools need ~4.5 mm shim stacks. Ideally I'd machine single shims, but the only stock I've got handy cleans up to only 3.2mm, and some fine shimming may be needed to fine-tune the tool height.<br />
<br />
: After sorting out the clamps so they were no longer twisting the aluminum flat bar stock, and switching to the short 45° turning SCMT06204 insert tool in the four way toolpost, to improve rigidity and get a well controlled tip radius, the finish was much improved. I'm still having problems getting an even thickness and am getting approx. 0.05mm variation, I suspect due to the aluminium bar stock distorting due to internal stresses as its surface is cut away. ''ToDo: try supergluing the stock to the faceplate before clamping to further reduce chatter and stop the warping.''<br />
: Looking back on this project a year later, its fairly obvious that the thickness variation was probably due to faceplate surface runout due to the damaged spindle nose.<br />
<br />
* Raphael has been working on a steel rocket nozzle with some assistance from myself. We have set up the rough cut chunk of ~ 50mm steel bar, faced both ends (to 50mm length) and turned the OD to 49mm to clean it up. Its going to need through drilling, probably some boring, and quite a bit of detail work on the OD. It will then need to be transferred to a jig in the drill press vice to allow a pattern of angled traverse holes to be drilled with acceptable accuracy.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_Lathe_Notes&diff=17614Ian M's Lathe Notes2024-02-07T13:04:50Z<p>IanM: /* Speeds & Feeds */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br />
<br />
''Currently these notes are semi-organized and non-authoritative. As I become more experienced with the RML CJ18A mini-lathe, I'm cleaning up, extending and reorganising them. Some lathe operating experience is assumed. If in doubt, '''*ASK*''' me, Andy H<sup>*</sup> , Jonathan H or another experienced minilathe operator!<br />
<br />
''* Andy H should be asked (for an authoritative answer) any questions involving RML usage policies or acquiring tooling or materials through RML.''<br />
<br />
== The Lathe ==<br />
Our Facilities page [[Facilities#Lathe|has]]:<br />
<blockquote><br />
'''Lathe'''<br />
[[File: Lathe2.jpg |200px|right | Lathe]]<br />
In the kitchen. <br />
<br />
Marked as a CJ18A Mini-Lathe from [[https://www.amadeal.co.uk/acatalog/CJ18A-Mini-Lathe-7x14-Machine-100mm-3jaw-Metric-With-Metal-Gears-AMA_LA_CJ18_M_3_MGRB.html Amadeal]]<br />
[[https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Manual]] <br />
<br />
[[Media:Lathe InductionNotes.pdf| Induction Document]]<br />
<br />
Possible upgrades:<br />
*https://www.youtube.com/watch?v=GwT-JQLbNPA<br />
<br />
''Please do not use the lathe until you have received induction'' <br />
<br clear=all><br />
</blockquote><br />
Its a Chinese import 7x14 mini-lathe. The 7x14 refers to the maximum diameter and length of work, in inches and is only a theoretical measure of the working envelope as you loose length to the chuck + any tailstock tooling, and the diameter is over the bed, not the cross-slide. See actual specifications below. <br />
<br />
Most if not all Chinese 7x10 to 7x16 mini-lathes seem to be remarkably similar (not uncommon with Chinese products due to [https://www.bunniestudios.com/blog/?p=284 Shanzhai (山寨)] )<br />
and the OEM of our Amadeal CJ18A Mini-Lathe was probably [https://www.made-in-china.com/showroom/cheap-lathe Yangzhou Realbull Machinery Co. Ltd]. Very similar lathes are also made by [https://www.siegind.com/lathe-machine.html Sieg], but their lathes tend to be slightly less sophisticated than the equivalent Realbull models.<br />
<br />
''N.B. Many Sieg parts are known to have slight but critical differences from Realbull parts, so '''DON'T''' order Sieg spares for a Realbull lathe!<br />
<br />
== Key Specifications ==<br />
Amadeal says the CJ18A Mini-Lathe is a 7x14 model with:<br />
<blockquote><br />
* Power 550 W<br />
* Distance between centres : 350 mm<br />
* Swing Over Bed: 180 mm<br />
* Swing Over Cross Slide: 110 mm<br />
* Taper: MT3<br />
* Tailstock Taper: MT2<br />
* Chuck diameter: 100 mm<br />
* Spindle Speed: 50 - 2500 rpm ''(with digital readout)''<br />
* Spindle Bore: 20 mm<br />
* Cross slide Travel: 65 mm<br />
* Range of Metric Threads: 0.5 - 2.5mm.<br />
</blockquote><br />
* The lead screw is metric, pitch 1.5 mm.<br />
* The spindle center is 90.6 mm above the flat of the bed (measured).<br />
<br />
Even though the compound and cross slide handwheels appear to be calibrated in thousandths of an inch, as ours is a metric machine, they only approximate that. One turn of a slide handwheel is 1mm advance, and they have 40 divisions, so each division is 0.025 mm, (approx. 0.984 [https://en.wikipedia.org/wiki/Thousandth_of_an_inch thou]). Similarly, the tailstock quill advances 1.25 mm per handwheel turn, which has 50 division dial, giving the same 0.025 mm divisions, but only 4 turns per 5 mm. The carriage handwheel is awkward - it moves approx. 19.2 mm per turn, and doesn't have a dial scale.<br />
<br />
== Notable Accessories ==<br />
We have:<br />
* [https://www.amadeal.co.uk/acatalog/160mm-Face-Plate-for-the-4-Mini-lathe-AMA_AC_CJ18A_FP160RB.html#SID=129 160 mm (6 1/4") Faceplate]<br />
* 100 mm (4") three jaw self-centering chuck (OEM standard) 22.5mm bore, with inside and outside jaw sets<br />
* 100 mm (4") four jaw (independent) chuck with reversible jaws (8 TPI screws)<br />
* Tailstock drill chuck (max. 13 mm dia.)<br />
* Live center for tailstock (+ OEM fixed center) <br />
* Four way Tool Post (OEM Standard)<br />
* [https://www.amadeal.co.uk/acatalog/Quick_Change_Tool_Post_for_the_mini-lathe.html Quick Change Tool Post] + 3 tool holders<br />
* [https://www.amadeal.co.uk/acatalog/Fixed-Steady-for-Mini-Lathes-AMA_AC_CJ18A_FSRB.html#SID=145 Fixed Steady Rest]<br />
* [https://www.amadeal.co.uk/acatalog/Travelling-Rest-for-Mini-Lathes-AMA_AC_CJ18_TSRB.html#SID=144 Travelling Steady Rest]<br />
<br />
''You'll find all of the above on the shelf above the lathe, with the accessories in the wooden box, apart from the steadies, which live next to it. Change gears, spare parts, and most cutting tool tips/blanks are in labelled white rectangular tins behind the lathe.''<br />
=== Measuring Tools ===<br />
We have:<br />
* Various dial indicators - the one with the adjustable magnetic base stand is the most convenient for most lathe setup work.<br />
* 25mm micrometer (in little grey case)<br />
* Grey case containing set of measurement tools including dial calipers, micrometer, steel rule (metric & inch), engineers square, and a fish-tail gauge<br />
<br />
''We currently lack''<br />
* ''A tool height setting gauge''<br />
<br />
=== Hand Tools ===<br />
Some common tools needed for normal use are kept with the lathe, in or attached to the wooden accessories box:<br />
* 2 mm Allen key - adjusting cross-slide and compound gibs<br />
* 4 mm Allen key - quick change toolholder tool clamping screws + height adjust, tightening dials<br />
* 5 mm Allen key - four way toolpost tool clamping screws, engaging/disengaging threading indicator<br />
* 6 mm Allen key - locking/unlocking quick change toolholder<br />
* 8 mm spanner - locking carriage when 8 mm socket can't be used, locking gib adjuster nuts <br />
* 13 mm spanner - changing chucks, locking steady rest jaws<br />
* Very long needle nose pliers - for grabbing swarf safely, holding one end of emery cloth safely so you can keep your fingers away from the jaws, and extricating small objects from awkward places.<br />
<br />
== Change Gears ==<br />
[[File:BC puller 1.jpg|thumb|Custom puller for B-C stub shaft]] [[File:BC puller 2.jpg|thumb|Pulling the B-C stub shaft]]<br />
See "Conquest Super Lathe" manual ([[#Manuals|below]]), section '''4.7 Change Gears''', PDF pages 28-29, but see below for mesh adjustment. The LittleMachineShop.com "Mini Lathe User’s Guide" (also below) section '''Threading''' gives a far better explanation, with pictures and diagrams, but its for a lathe with a US 1/16 inch pitch leadscrew, not a metric 1.5 mm pitch one like ours, so you *MUST* ignore all the tables in that section, replacing them with metric mini-lathe (with 1.5 mm pitch leadscrew) equivalents. <br />
<br />
We have the following tooth count gears: 20,20, 30, 35, 40,40, 45, 50,50, 60,60, 80,80<br />
which consist of the OEM power feed gears + the metric change gear set. Apart from the metal 20 tooth pinions, they are all plastic, probably Delrin if the molded in 'POM' marking can be trusted, but possibly plain Nylon 6, and are metric Module 1.<br />
<br />
If we wanted to add the capability to cut US/Imperial threads we'd need to buy additional 55, 57 and 65 tooth gears, and possibly a 21 tooth metal pinion.<br />
<br />
CGTK's [https://www.cgtk.co.uk/metalwork/calculators/changegears/minilathe?gears1=20,20,30,35,40,40,45&gears2=50,50,60,60,80,80&gears3= Change Gear Calculator] ''(link preloaded with our gear list)'' is useful if you don't want to calculate the ratios from first principles. Not all suggested combos will physically fit.<br />
<br />
* Take care *NOT* to loose the keys in the A and D shaft keyways - turn each shaft till the keyway is up before removing the gear. <br />
* The B and C gears are coupled by a hollow stub shaft (with an integral key), which is so tight in the gears it has to be pressed or driven out - I've made a puller just for this task, kept in the change gears tin.<br />
* The center of the B-C stub shaft *MUST* be lubricated where it runs on its pin on the change gear banjo bracket, with grease or heavy oil. ''Seizure of the stub shaft due to running dry is a frequent cause of catastrophic mini-lathe geartrain failures!''<br />
* Don't get oil on the change gears as it can cause plastic gears to crack. Only PTFE drylube or plastic compatible white grease should be used on their teeth. <br />
* Adjust the B-C pin position in the straight slot first to set the C to D gear mesh, tighten its nut, then swing the whole banjo about the D shaft boss to set the A to B mesh, and finally tighten the banjo clamping nut.<br />
* Check both gear meshes have running clearance by turning the chuck by hand enough to complete one full turn of the leadscrew, and by attempting to turn the intermediate gear(s) to assess backlash, If excessive resistance is felt or if there's significant backlash, readjust the gears. If you have difficulty judging the mesh, a strip of 80 gsm copier paper (approx. 0.1 mm thick) wound into the meshing teeth before tightening the stud or banjo will give appropriate clearance once removed. Once setup, check the gears run quietly under power.<br />
* If the sum of the tooth counts C+D is the same as for the ones you just removed and they were correctly meshed, you don't need to move the stub shaft pin. If A+B is <u>also</u> the same, you don't need to move the banjo. e.g. If it was set up for 16:1 reduction power feed, 1 mm (40:60 - 50:50) for M6 and 1.5 mm (e.g. 40:60:40) for M10 pitches can thus be achieved by only swapping gears. <br />
<br />
''The change gears, puller, etc. and a box spanner for the banjo nut are kept in a white rectangular tin behind the lathe.''<br />
<br />
=== Power Feed ===<br />
When used for turning with power feed, the change gears should be set for a 16:1 reduction (A:20 : B:80 - C:20 : D:80) using the pair of small metal 20 tooth pinions and the 80 tooth plastic gears (largest in set), for a feed of 0.09375 mm per turn (1.5 mm/16). Unless continuing your threading project the next session, please re-fit the 16:1 power feed set after threading so the power feed is ready for use. <br />
<br />
* *ALWAYS* leave the feed direction selector lever in its neutral (no feed) position, and the half-nuts open after use.<br />
* *ALWAYS* check the carriage lock is disengaged before engaging power feed. Unlock the carriage after use. <br />
<br />
=== Threading Dial ===<br />
The threading dial is an aid to re-engaging the half-nuts at the right moment so the tool will retrace its previous path cutting deeper, rather than offsetting axially some fraction of the thread pitch and ruining your work. Its based on the concept of the lowest integer multiples of the leadscrew and thread ''(being cut)'' pitches that exactly match, but for mechanical simplicity it only covers certain selected multiples of the leadscrew pitch.<br />
<br />
We have a choice of three pinion gears:<br />
{| class=wikitable<br />
|+ Threading dial Pinion Gears<br />
|-<br />
! Teeth !! Colour Dot !! Usable lines !! OD gear !! Dist. per turn<br />
|-<br />
| 14 || Red || 1,7 || 7.51 mm || 21 mm<br />
|-<br />
| 15 || Orange || 1,5,9 || 8.05 mm || 22.5 mm<br />
|-<br />
| 16 || Green || 1,4,7,10 || 8.37 mm || 24 mm (2 mm/div)<br />
|}<br />
They are now colour coded, with a paint dot on the gear end face ''(the only non-wear surface)''. The 16 tooth one is normally left on the lathe, but disengaged when not threading to minimise wear on the lead screw. The others are kept in the Change Gear tin.<br />
<br />
There's a threading dial 'pickup' calculator here: https://www.cgtk.co.uk/metalwork/calculators/threaddialindicator <br />
<br />
Initially select ''Lathe:'' '''Custom''', and enter the following below:<br />
* ''Units:'' '''Metric'''<br />
* ''Lead Screw Pitch (mm):'' '''1.5'''<br />
* ''Thread Dial Indicator Gear Teeth:'' '''16,15,14''' <br />
* ''Lines on Thread Dial Indicator:'' '''12''' <br />
* ''Line Marking:'' '''Every Line Numbered'''<br />
Note the teeth list is entered in reverse order so the resulting table highlights any required pinion changes.<br />
<br />
N.B. The dial is only friction clamped to the pinion by its center screw. If you have any reason to suspect it may not be properly aligned: <br />
# With the power off and the carriage unlocked, engage the feed direction lever upwards. You'll probably need to turn the chuck by hand to get it to engage.<br />
# If the threading indicator isn't already engaged, loosen the threading dial support block bolt, pivot the block to engage the pinion with the leadscrew and retighten the bolt.<br />
# Engage the half nuts, again turning the chuck by hand till they drop in. <br />
# Turn the chuck a couple of turns, top towards you to take up any backlash, then lock the carriage, taking care not to push it left while locking it.<br />
# Loosen the screw securing the dial to the pinion.<br />
# Align the '1' line of the dial with the index line, by rotating the dial clockwise, then retighten the screw.<br />
# Don't forget to disengage half-nuts and unlock the carriage!<br />
<br />
The above instructions should result in the half-nuts engaging cleanly when exactly on any valid line when threading towards the headstock. If it is required to thread away from the headstock, there will be a slight offset from the line due to backlash between the spindle gear and leadscrew, so engage slightly early.<br />
<br />
Changing the pinion:<br />
# Loosen the threading dial support block bolt and disengage from the leadscrew.<br />
# Undo dial center screw, and remove it and the dial, dropping the old pinion out the bottom.<br />
# Oil the shaft of the new pinion with a drop of light oil and insert it from below, gear end down.<br />
# Refit dial and screw.<br />
# Check the dial and pinion turn freely with minimal resistance.<br />
# Align as above.<br />
<br />
== Tailstock and Steadies ==<br />
These are mostly used to support long work ''(long with respect to its diameter)'' to improve rigidity, increasing accuracy and reducing chatter. The Tailstock quill is also used with a drill chuck for drilling.<br />
=== Tailstock ===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock base]]<br />
The tailstock can be offset to turn shallow tapers between centers. We don't currently have the accessories to turn between centers, namely <s>a MT3 dead center for the spindle, or</s> any drive dogs for the work. Also realigning the tailstock after turning a taper can be a PITA. The photo shows the tailstock adjusting screw locations ''(C - Lateral, and D - Skew)'' and the block on the baseplate they engage with. Adjustments can only take effect when the tailstock locking lever is eased to take the pressure off the baseplate. As we don't have a MT3 center, one has to turn a fresh point on a test workpiece for a rough tailstock alignment reference. Fine alignment, to avoid inadvertent taper turning, can be done by mounting a long precision ground bar between the chuck (or preferably a center in the spindle), and a dead center in the tailstock and sweeping it with a dial indicator on the carriage. Finally a test cut should be taken at either end of a bar between centers, and the diameters checked with a micrometer. Assuming the bed has previously been properly levelled and shimmed to take out twist ''(not the case at RML as we don't have it bolted down)'', any remaining difference in diameter will be double the tailstock offset, smaller at the tailstock being offset towards the front. Fine adjustment cant be achieved by jacking with the screws, its best to ease the adjusting screws, bump the tailstock into alignment then take up the screws again, checking the alignment is maintained when the tailstock is unlocked and relocked. There is no vertical adjustment, though shims can be added between the tailstock and its base.<br />
<br />
==== Tailstock Quill ====<br />
There is a metric/imperial scale on the top of the quill, read against the end of the tailstock, for depth measurement when drilling. The tailstock quill has a 1.25 mm pitch thread and a 50 division dial. Each division is therefore 0.025 mm, and it only takes 4 full turns of the handwheel to move the quill 5 mm. <br />
<br />
To eject MT2 taper tooling and centers from the tailstock, wind the quill all the way in.<br />
<br />
N.B. The quill anti-rotation pin (dog-tip setscrew + locking nut in top of tailstock near to the quill lock) is only M5. It will sheer if a large diameter drill jams in the work. Please back it out clear of its keyway if using large drills, and use alternative methods of preventing chuck rotation. To re-engage it, crank the quill out till you can see the keyway, align it with the screw and screw in the screw till it gently bottoms out, then back it off a quarter turn. Try twisting the quill to check its properly engaged, then tighten the locking nut gently to hold the screw in position clear of the bottom of the keyway.<br />
<br />
=== Steady Rests ===<br />
We have two, both with brass tips that must be kept lubricated during use.<br />
<br />
The fixed steady mounts on the ways, and is most useful when turning longer work that wont fit through the spindle bore. Adjustment is critical, and the surface the tips run on must be smooth and concentric, as any misalignment that forces the work off center will result in the work wobbling in the chuck, marring it, with a high risk of it becoming un-chucked, which can be dangerous at speed.<br />
<br />
The travelling steady mounts to the headstock side of the carriage to locally resist the deflection of thin long work, due to the cutting forces. It only has two tips, to resist climb, and deflection away from the tool, and requires readjustment after every cutting pass.<br />
<br />
== Tooling and Tool Holders ==<br />
'''Key dimensional data:'''<br />
* The quick change holders accept up to 10 mm shank tools. <br />
* The four way toolpost has 50 mm long sides, a seat width of 15 mm and can clamp tools of up to 5/8" (15.875 mm) shank ''(check this)'', but the slot base is only 10.4 mm below the spindle center so cannot be used with >10 mm shank tooling unless it has a dropped tip. Large tooling with a centered tip is also problematic as you run out of height above the shank when trying to shim to match the spindle center height. <br />
<br />
===Quick Change Toolpost===<br />
I've got the quick change toolpost and toolholders setup for mostly easy use. The three toolholders came with cantilever height setting arms which historically haven't been installed as the supplied fixing screws were too short. That's all now sorted out and a HSS RH turning tool and a HSS hand-ground grooving/parting-off tool are now mounted in two of the holders and set to height. The third is kept free for other tools. <br />
<br />
The quick change toolpost has been modified with a spring to press the dovetail clamp outwards and help stop it twisting or flopping about to ease toolholder fitting and removal. The dovetail clamp (socket headed screw on toolpost side opposite dovetail) feels a bit stiffer than before, but will take less than half a turn to go from open (with the toolholder lifting out or dropping in easily) to fully clamped. As there is so much less clearance in the open position you should no longer need to wiggle the toolholder while clamping it to get a consistent height. If the dovetail clamp ever gets misaligned, twist it straight by eye, slacken off a bit further than usual to get a toolholder on, clamp it to align the dovetail then release, reseat the toolholder and re-clamp to ensure its at its preset height. You cant adjust the height by 'jacking' with the height screw due to its offset leverage. Instead, back off the height screw and hold the toolholder at the desired height while locking the dovetail clamp, then adjust the height screw (and locking nut) to hold it there, then check it doesnt change height significantly when you unclamp and reclamp the dovetail. <br />
<br />
Unfortunately the OEM height setting screws foul the toolpost locking nut handle. Currently, if you need to swap toolposts you will have to first remove the quick-change tool holder from the post. There is enough nut handle swing to allow the quick change toolpost to be unclamped and rotated to fine set the tool angle without removing the toolholder. It also seems the mating surfaces may be slightly out of square, as if you rotate the toolpost 90° or 180°, the nut swing may be insufficient to re-clamp it without removing the toolholder to do so. Add a M10 washer under the locking nut if the handle ends up pointing in an undesirable direction! A thin M10 washer is kept with the toolpost collar for this purpose, and will shift the handle position by about a third of a turn. <br />
<br />
''ToDo: Make a taller nut of a similar pattern, to clear the height setting screws.''<br />
<br />
===Four Way Toolpost===<br />
The OEM four way toolpost is significantly more rigid than the quick change toolpost + holders because it has fewer and thicker parts and less overhang. Therefore the four way toolpost should be used when using carbide tooling. It requires shimming under the tool to set the tip height to the spindle center height - see below. The tool shanks are mostly significantly less than 15 mm wide, so need to be centered under its clamping screws, tempting as it is push the shank in for full side contact with the toolpost. If possible clamp the shank with all three screws not just two.<br />
<br />
==== Shimming ====<br />
We typically only mount up to two tools, and want maximum rigidity, so use 50 mm x 15 mm shims, (the full seat area), preferably with deburred edges and radiused corners so they aren't a hazard to the operator.<br />
<br />
We have pre-cut and marked shims of the following thicknesses: <br />
* 1x 3.23 mm, 2.42 mm, 1.56 mm, 0.32 mm, and 0.25 mm<br />
* 2x 1.00 mm, 0.77 mm, 0.12 mm, 0.11 mm, 0.10 mm and 0.05 mm<br />
* 4x 0.53 mm<br />
<br />
Our shims are mostly found materials (hence the awkward thicknesses) and are mostly a mixture of aluminium and steel, with a couple of GRP ones. The toolpost seat '''<u>must be absolutely clean</u>''' to avoid embedding debris in the aluminium or GRP shims, to get a consistent height and avoid tilting the tool - wipe it every time you change a tool! Put the thin shims at the bottom of the stack to avoid the tool shank edges creasing them. Shims are kept in a little yellow plastic box with a clear lid, near the carbide tools case.<br />
<br />
I made a tool height setting gauge (T shaped black acrylic with steps in its sides) which can be used to check the tool tip height matches the spindle center height using either the flat of the ways or the saddle as a reference. The tool tip should just fit under the lip of the appropriate step, with the T arms across the ways flats or on the saddle. It is kept in the box with the carbide insert tools.<br />
<br />
''ToDo:'' <br />
<br />
* ''Cut more shims neatly, mark them with their thickness.''<br />
* <s>''Do test cuts and start noting shim stack-ups for various tools.''</s><br />
* ''Organise shim storage!''<br />
<br />
=== HSS Tools ===<br />
[[File:Tool Bit Geometry.jpeg|thumb|Single point cutting tool geometry]]<br />
Our HSS tools are made from 8 mm square bar stock, hand-ground to tip profile in-house. See LittleMachineShop's [https://littlemachineshop.com/images/gallery/instructions/grindingtoolbits.pdf Grinding Tool Bits] notes. <br />
<br />
I've installed our usual HSS LH turning and parting off tools in two of the quick change holders and set the heights correctly. There are a couple of other HSS tools or tool blanks knocking about. Taking heavy cuts turning steel (even with good cutting oil) blunts HSS tools fairly quickly, which are time-consuming to re-sharpen nicely without a dedicated tool & cutter grinder with appropriate jigs. Its worth noting that the usual 'speeds & feeds' tables are commonly based on surface speeds expected to give a half hour (active cutting) tool life before resharpening.<br />
<br />
I touched up the LH turning tool by lapping on wet & dry (silicon carbide) paper on glass (Aka: [https://en.wikipedia.org/wiki/Scary_sharp 'Scary Sharp']) working upwards through the grits 200, 400, 600 and finally 1000, initially 'bluing' the surfaces to be lapped with a marker pen to see which areas needed taking down more. The end of the tool was significantly uneven so I touched that up freehand on the bench grinder to flatten it when it became apparent that 200 grit lapping wasn't cutting where it needed to. There was an existing micro-bevel on the leading side, which I kept. Finally I 'dubbed' the leading corner vertical edge on the 1000 grit to give it a very slight nose radius. A test cut on brass gave a very nice finish when turning.<br />
<br />
''Ian B has purchased some spare 8mm HSS tool blanks - talk to a lathe trainer if your proposed lathe work needs custom ground HSS tooling.'''<br />
<br />
=== Brazed Tungsten Carbide Tools ===<br />
Somewhat of a half-way house between hand ground HSS tooling and insert tooling with the disadvantages of both and some more besides - e.g. they are much harder to sharpen. So why do we bother? Some tool geometries would be awkward and tedious to hand grind, and Chinese import brazed carbide tooling is about half the price of similar HSS tooling, and far more readily available. Also, for space constrained tooling like boring bars, if you want carbide, for insert tooling, the size of the insert and its clamping seriously limits the minimum hole diameter you can work in. I have purchased a set of 3/8" shank brazed carbide tipped boring bars, but we currently cant sharpen them, due to lack of a diamond grinding wheel. <br />
<br />
=== Tungsten Carbide Insert Tools===<br />
Decoding ISO insert tooling part numbers: https://www.cutwel.co.uk/blog/learn-the-turning-tool-iso-code-system<br />
[[File:Carbide set.jpg|800px|thumb|left|Our set of Tungsten carbide insert lathe tools (before the new inserts were fitted)]]<br />
<br />
{| class=wikitable<br />
|+ Tools, left to right, (+ last across top):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| SSKCR0610H06 || 75° through boring || SCMT06204 || Long || 6 || 6.34 || ''4.33''<br />
|-<br />
| SSSCR0610H06 || 45° deep facing, internal chamfering || SCMT06204 || Long || 6 || 6.13 || ''4.58''<br />
|-<br />
| SWUCR0610H05 || 93° boring, deep facing || WCMT050308 || Long || 6 || 6.22 || ''4.48''<br />
|-<br />
| SWGCR0810E05 || 90° RH turning & facing || WCMT050308 || Short || 8 || 8.25 || '''2.45'''<br />
|-<br />
| SSSCR0610E06 || 45° turning, chamfering || SCMT06204 || Short || 8 || 8.75 || ''1.93''<br />
|-<br />
| SSBCR0610E06 || 75° RH turning, chamfering || SCMT06204 || Short || 8 || 8.72 || ''1.98''<br />
|-<br />
| LW0810R-04 || 60° external threading || JCL15-120 || Short || 8 || 7.44 * || ''3.28''<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || 8.23 || ''2.5 ?''<br />
|-<br />
| LN0813R-04 || 60° internal threading || JCL15-120 || Long || 7.95 || 7.44 * || ''3.28''<br />
|}<br />
<br />
{| class=wikitable<br />
|+ More Tools, (loose in tin):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || ~8.5 (not in use) ||<br />
|-<br />
| [https://www.glanze.co.uk/product/glanze-12-mm-60-degree-metric-internal-threading-tool/ Glanse SIR0012K11] || 60° internal threading bar || 11IRA60 || Long || 12 dia || ??? || ???<br />
|}<br />
''Shim stack heights in bold are tested, in italic are only calculated.'' ''Tip heights marked * are with new JCL15-120I inserts. The single remaining plain JCL15-120 insert has a slightly higher tip height.''<br />
<br />
Carbide tooling typically requires two to three times more speed than HSS and at least a couple of 'thou' depth of cut for best results.<br />
<br />
Chatter can rapidly kill carbide tooling by chipping the cutting edge. To improve rigidity and reduce the risk of chatter, the cross-slide and compound gib screws need to be well adjusted so there is minimal play in the slides, tool stick-out should be minimised, the four way toolpost should be kept over the cross-slide, and the work should be kept close to the chuck (or otherwise supported by tailstock or steady rest) to avoid excessive deflection.<br />
<br />
Thermal shock is almost instant death to carbide, and when dry cutting the insert tip can run very hot, so do not add extra cutting fluid manually during the cut. Pre-apply what you need, evenly, before starting the cut.<br />
<br />
Parting off or facing to center is high risk - if the tool tip is even slightly below center or if tool or work deflection takes it below center, the work will tend to climb over the tool tip as the cut approaches center, breaking the insert. To avoid this, the tool should be shimmed slightly above center, sufficient to allow for work and tool deflection, and unless very close to the chuck, a steady should be used. Its often preferable to part to a couple of mm dia. remaining then stop and saw through the remainder. Parting off hollow parts is much lower risk.<br />
<br />
Further investigation of the Tungsten carbide insert tool height situation is not encouraging - the so-called 'set' in question does not have a consistent tip height ''(see above table)''! In a real set, the insert seats *should* be machined allowing for the insert thickness to bring all the cutting edges to the same height with respect to the shank underside. However if you place them tip to tip on a table its easy to see there is considerable height variation, so they need to be individually shimmed (or at best, one machined shim will only be right for two or three tools). At this time we don't have dedicated shim stacks for each tool.<br />
<br />
A 2.42 mm thick shim brings the SWGCR0810E05 90° RH turning & facing tool almost exactly to center height, and good results were obtained turning 1" steel pipe. However facing 50mm steel bar stock to center found it to be slightly low, leaving a fractionally under 0.05 mm 'pip' so it needs another 0.03 mm to bring it fractionally above center. Fractionally too high is generally preferable to fractionally too low, due to tool deflection, so adding an 0.05 mm shim to the stack should produce optimum results.<br />
<br />
==== Inserts ====<br />
Ian B has purchased the spare inserts we needed in sets of five. He even was able to get the CK3 parting-off inserts which had been difficult to source!<br />
<br />
Inserts used in above tool set:<br />
* 3x SCMT06204 (square, indexable) https://www.rdgtools.co.uk/acatalog/SCMT-06-Carbide-Insert.html<br />
* 2x WCMT050308 (triangular, indexable) https://www.rdgtools.co.uk/acatalog/WCMT-05-T3-08-5XTIP-8813.html<br />
* 2x JCL15-120 (60 deg threading point) https://www.rdgtools.co.uk/acatalog/X5-JCL-15-120L-THREADING-TIPS-60-DEGREE--X5-TIP---23455.html<br />
* CK3 (parting off) https://www.rdgtools.co.uk/acatalog/CK3-CARBIDE-TIPS---PARTING--BOX-OF-5PCS--9437.html<br />
<br />
Inserts used in other tools:<br />
* 1x CK3 (as above) also missing from spare parting off tool<br />
* 1x 11IRA60 in Glanse threading bar + 1x spare<br />
<br />
=== Drills ===<br />
Various sizes of center drills are kept in a plastic bag next to the wooden accessories tray. There's also a small box of 2.5 mm center drills.<br />
<br />
We have a set of 11 TiN coated HSS drill bits from 1.5 to 8 mm, (in a cylindrical plastic index box) for tailstock drilling of brass, aluminium and non-abrasive plastics. To keep them sharp enough for the precision work we expect from the lathe, please don't use them for steel or reinforced plastics, and don't borrow them for non-lathe use. Metric and US [https://littlemachineshop.com/reference/numberdrillsize.php numbered]/[https://littlemachineshop.com/reference/letterdrillsize.php lettered] general use HSS drill bits are kept in two red metal index boxes next to the drill press.<br />
<br />
== Using the Lathe ==<br />
=== General ===<br />
Making dimensioned parts is primarily done by touching off the tool tip on a reference surface (with the lathe stopped, turning the chuck by hand), zeroing the handwheel dial, then manually counting turns and divisions. When backing off the tool its best to do so by exactly one whole turn so you don't forget the previous dial position. Stopping and measuring the work before taking the final cuts is essential if high accuracy is required. ''I've changed out the dial setscrews for flat tip ones with a tiny slug of solder under them so the dials are now friction fit on their shafts. i.e. if you hold the handle firmly taking up the backlash in the direction of cut, you can zero the dial just by grabbing and twisting it.''<br />
<br />
Carriage movement is less easy to measure as the handwheel is uncalibrated and advances an awkward bit over 19.2 mm per turn. Your options here when shoulders or other features must be exactly positioned are, in order of increasing accuracy: <br />
* Use measuring instruments, scribe the work at the desired length then work to the scribed line. Its often convenient to black the work with a permanent marker, then scribe with the tool tip, turning the chuck by hand.<br />
* for short distances, lock the carriage and use the compound, set parallel to the work<br />
* Set up a long travel dial indicator to measure carriage motion. <br />
N.B. with the leadscrew stopped, and the threading dial engaged, with its default 16 tooth gear, it will make one turn for every 24 mm of carriage movement (2 mm/div). This isn't accurate enough for positioning but is sufficient to check you aren't out by a whole mm or more.<br />
<br />
Do not allow any solvents to contact the chuck guard clear plastic as it will make the plastic brittle, or even craze it, and try to avoid melting it with the work light!<br />
<br />
===Speeds & Feeds===<br />
The surface speed of the tool relative to the work (or visa versa) is important, and best results will be achieved when it is in a tool type and material specific range. Because the surface speed is proportional to the diameter and the spindle RPM, it is usual to vary the spindle speed in inverse proportion to the diameter to get the surface speed in the desired range, and keep it there as the tool tip moves closer to the spindle axis. <br />
<br />
A cutting speed chart for HSS tooling, published by Model Engineer magazine can be found [https://www.model-engineer.co.uk/sites/7/documents/cutting%20speed%20chart.pdf [here<nowiki>]</nowiki>]. The second row is the target feed rate and the rest of the chart, apart from the diameter column is RPM.<br />
<br />
For carbide tooling cutting iron and steels, recommended speeds are generally three times higher than for HSS, but the CJ18A 2500 RPM max. spindle speed (in high gear) means you can only reach the optimum speed range for over 15 mm dia work. For small diameter work, HSS tooling may well be a better choice.<br />
<br />
An online metric speeds calculator is here: https://www.cgtk.co.uk/metalwork/calculators/cuttingspeeds <br />
<br />
How to do the maths to calculate speeds and feeds: https://www.cutwel.co.uk/blog/speeds-feeds-made-easy<br />
<br />
If you can hear the lathe 'sing' as it cuts, you are getting chatter, which invariably results in poor surface finish. Try decreasing (or possibly increasing) the spindle speed till the resonance stops. <br />
<br />
Once you have a wavy surface due to chatter, a light cut wont clean it up as the tool 'twangs' from peak to peak. You have to take a deep enough cut to get under it. For precision parts, its therefore desirable to take a trial finish cut while still 0.5 mm or so oversize, to give an opportunity to tweak the cut to get a good finish, check for taper, and that the part wont be undersize (on your test finish cut nominal diameter).<br />
<br />
=== Slide Locks ===<br />
* The carriage can be locked to the ways using the M5 hex screw through the top of the saddle to the left of the cross-slide. Double check the leadscrew is disengaged and the half-nuts open before locking it. Lock it when facing.<br />
* The cross slide can be locked by a M4 socket headed cap screw just in front of its middle gib screw. Locking the cross slide is helpful when turning very shallow conical features where the cross slide handle is in the way of the compound.<br />
* The compound slide can be locked by a M4 socket headed cap screw in line with the edge of the toolpost mount on the side with the gib adjustment screws. In normal use it should be kept backed off half a turn but it is desirable to tighten it for parting off operations to keep the resulting end faces flat.<br />
<br />
=== Compound ===<br />
The compound consists of a locking swivel and a top slide allowing cuts to be made at an angle to the axis e.g to produce bevelled or tapered features. There is a difference between US and UK usage, in the US a compound angle of 0° means the compound slide is parallel to the cross slide, but in the UK, 0° is parallel to the ways. The compound angle indicator on the CJ18A follows UK practice, 0° parallel to the ways, but it is not to be trusted, its out by a few degrees!<br />
<br />
One of the deficiencies of the CJ18A lathe is the difficulty of setting the compound angle. It is held and locked by two screws hidden under the top half of the compound slide, which must be wound back till its toolpost end is clear of the pivot point to access them. This may have to be repeated several times to snug them up enough to tap it to the desired angle, then finally tighten them. <br />
<br />
We generally keep the compound slide set approximately parallel to the ways so it can be used for short-distance longitudinal positioning without measuring. However it is unlikely to be closely parallel unless a test bar has been swept with a dial indicator on the slide, or test cuts made on a large OD workpiece and checked for taper.<br />
<br />
=== Chucks and Chuck Jaws ===<br />
==== Terminology ====<br />
* Inside jaws have steps on the outside to grip the ID of hollow work, but can also be used as outside jaws on small diameter parts (i.e. that fit through the spindle). <br />
* Outside jaws have steps on the inside to grip the OD of the work.<br />
* Universal chucks have a scroll plate with a spiral screw thread that moves all the jaws.<br />
* Independent chucks have individual adjusting screws for each jaw.<br />
<br />
==== The Chucks ====<br />
* The three jaw universal chuck can only grip near round or hexagonal work, which it centers, but its concentricity is not perfect so e.g. if you reverse the work and continue turning at the same diameter from the other end, you will see a line where the turned surfaces meet. It has separate sets of inside and outside jaws, and we normally keep the inside set installed to use as outside jaws for small diameter work.<br />
<br />
** Our jaws are individually numbered, stamped in the groove. They must be fitted in the correct sequence. The jaw slots are not clearly marked. Lowest runout for small dia. parts is achieved if you fit the jaws with #1 anticlockwise of the makers mark, then continue anticlockwise for #2 and #3.<br />
** A large strong rubber band is a great help getting all the jaws started on the scroll together - with slots #1 and #3 above the centerline and the scroll thread outer tip between #1 and #3, insert jaws #1 and #2 and put the rubber band round them to keep them in their slots. Insert jaw #3 and stretch the rubber band over it to hold it up into its slot. If the scroll was positioned correctly, all jaws should be at the same initial radius. The jaws can now be cranked in with the chuck key and they should all engage in step so they meet in the middle.<br />
:: ''Mini-lathe.com have the best instructions for [https://www.mini-lathe.com/mini_lathe/chucks/chucks.htm#Installing_Chuck_Jaws changing the jaws].'' <br />
<br />
* The four independent jaw chuck can grip most roundish or squarish work, which can either be carefully centered by the user, or deliberately gripped off-center. <br />
** Its jaws are reversible so can be swapped from inside to outside by simply cranking each jaw out and reinserting it the other way round, one at a time. DON'T move the jaws to different slots as they are likely to bind.<br />
** When setting up to face the sides of rectangular objects held crossways, it may be helpful to use both inside and outside jaw orientations, in symmetrical opposing pairs.<br />
** Its screws move their jaw 1/8" (3.125 mm) per turn<br />
<br />
* The jaws must '''never''' protrude from the chuck OD by more than one step, and for safety, its preferable they don't protrude at all, as they make the gap between the front of the bed and the chuck body an even more unforgiving meat grinder, and as the number of teeth engaged with the scroll or screw decreases, they loose strength, just when you need it the most to grip larger/heavier work. <br />
<br />
''Neither chuck is well suited to gripping tapered work safely. When seating work that doesn't quite fit through the chuck bore (which is larger than the 20mm spindle bore limit), be careful that it isn't seating on the chamfered edge of the chuck bore as it is far to easy to get the work slightly cocked so it doesn't run true.''<br />
<br />
==== Changing Chucks ====<br />
* When changing chucks, use the small grey plastic mat to protect the ways under the jaws in case you drop the chuck.<br />
* The spindle nose has two patterns of holes - the three hole pattern is for the three jaw chuck and the faceplate, and the four hole pattern is for the four jaw chuck. One hole is shared between the patterns, and is marked on the spindle nose.<br />
* To fit a chuck:<br />
** First check that the spindle nose and chuck back and recess are free of swarf, grit or other debris. Any foreign objects will tilt the chuck causing excessive runout and may mar the surfaces.<br />
** Remove the nuts and split lock washers from its studs, line its studs up with the hole pattern (preferably with the stud nearest anticlockwise to the makers mark through the marked spindle hole), fit and hold it in place with your right hand, and with your left, get the lock washer and nut on the top stud, and take up the slack.<br />
** One one nut is on, you no longer have to worry about dropping it, and can work round fitting the remaining washers and nuts, taking up the slack on each as you fit it. <br />
** Next, work round again getting them all finger tight, then tighten them gently, and finally work round fully tightening them. <br />
* Removal is the reverse of refitting. Put the washers and nuts back on the chuck's studs so they don't get lost.<br />
<br />
==== Gripping Threaded Work ====<br />
It is generally undesirable to chuck work gripped on a screw thread, as it is difficult to hold the work securely and get good concentricity while avoiding crushing the thread crests. However, if one must, one of the better ways of doing so is to wind a wire helix to fit the thread then clamp on the outside of the wire so it seats on the flanks of the thread. The wire should be mild steel or soft iron for steel parts and copper for aluminium and brass parts, single strand, round and of uniform diameter a little less than the thread pitch. It can be wound on the lathe, in reverse, by chucking a sacrificial mandrel of the same diameter and thread pitch, hooking the end of the wire round or under the jaw, against the direction of rotation, then holding the other end of the wire under tension with pliers and starting the lathe dead slow. Once wound and removed from the mandrel, the ends must be trimmed then it should be screwed on to the threaded work to provide a surface to chuck on.<br />
<br />
=== Faceplate Work ===<br />
Faceplate work is probably the most dangerous operation you can (or rather should) perform on a lathe. The working area is a large diameter spinning surface with protruding clamps to fixture the part that it is impractical to guard. Protruding clamps, studs, nuts etc. are very difficult to see at speed.<br />
<br />
'''Treat the faceplate with great respect and caution if you wish to continue to be able to count to ten on your fingers!''' <br />
<br />
The 65 mm cross-slide travel vs the 80 mm faceplate radius is a serious limitation that may require creative compound, toolpost and tool setups for larger parts, and doing full face cuts in two sections.<br />
<br />
''It is common practice to skim the faceplate to ensure it runs true. We have not (yet) done this, and wont till the spindle is in better bearings and the nose reground to minimise runout.''<br />
<br />
==== Clamping ====<br />
Open ended/sided clamps should be oriented so that cutting forces drive the work towards the clamping bolt/stud, not out from under the clamp. Minimize the protruding length of thread past the clamping nut, if necessary using sacrificial bolts or studs you can cut to length, or even using a long M8 stud for one of the faceplate mountings, so you can get a clamp nearer to the faceplate center. Double-check all clamps are secure, manually turn the faceplate to check the work and clamps clear the ways, top-slide and toolpost, and stand out of the 'line of fire' (a disc extending from the faceplate) when spinning up the work for the first time. <br />
<br />
If you need to machine close to a clamp, consider marking a safe limit circle on the faceplate and work with a marker pen to make it easier to see how close the cutting tool is to crash disaster. <br />
<br />
I strongly advise reading chapter two of Tubal Cain's book "Workholding in the Lathe" several times before your first faceplate setup, and if possible get another experienced lathe user to check your first few setups before spinning them up.<br />
<br />
==== Chuck Guard Removal ====<br />
The faceplate is too large diameter to fit under the chuck guard, but the guard has an interlock switch wqhich must be closed for the lathe to run. The guard is now fitted with wing nuts so it can be removed allowing the the interlock switch to close when using the faceplate. It *SHOULD* *ALWAYS* be refitted if a chuck is fitted, except when turning work too large to clear the guard. <br />
<br />
''The chuck guard is primarily there to make it very difficult to start the lathe without removing the chuck key and to reduce the area of large diameter spinning surface exposed. It may slow down the projectile if a chuck sheds a jaw but is unlikely to stop it. Also it serves to contain coolant spray spun off the chuck. As we don't use flood coolant this usually isn't an issue for us. As setting up for faceplate work doesn't use a chuck key, and the most hazardous zone is the face of the faceplate, with its spinning projecting clamps, with full access required for machining operations, which a guard would not cover, the consensus is that removing the guard is an acceptable risk.''<br />
<br />
=== Turning and Facing ===<br />
We are getting good results in aluminium, brass, and even steel using HSS cutting tools in quick-change tool holders, and the ~ 94 um/turn power feed. Unfortunately due to lack of rigidity in both the machine and smaller diameter parts, if you don't want the outer end to be over diameter, a light final cut and multiple 'spring' passes will probably be required.<br />
<br />
For aluminium, a sharp HSS tool and 0.5 mm (20 div) depth of cut gives good results with power feed for rapid stock removal. Its also easy maths as each cut takes ~ 1 mm off the diameter. Finish cuts should be much finer, 0.1 mm (4 div) is 'in the ballpark'.<br />
<br />
For steel, using carbide insert tooling, a 0.25 mm (10 div) depth of cut is more appropriate, and with pre-applied cutting oil, gives reasonable results with power feed if you use enough speed. The maths is not quite so easy as you are only taking 0.5 mm off the diameter per pass. Again, use finer finish cuts but try to plan your cuts so the final cut is still cutting, not smearing the surface!<br />
<br />
When facing or parting off, some skill is required to turn the cross-slide handwheel steadily to get a decent finish and to avoid shock-loading the tool tip. Increasing the spindle speed in one or more steps to keep up with the reducing diameter is advisable, but avoid speeds that cause resonances (resulting in chatter). When parting off, small through-hole parts may be caught on a thin rod chucked in the tailstock, and pre-positioned inside the work with its tip right up to the parting off position.<br />
<br />
==== Using the Steady Rests ====<br />
For the fixed steady rest, see Blondihacks' Lathe Skills #26 - How To Use a Steady Rest! [[#Youtube_Playlists_&_Videos|{below}]]<br />
<br />
Ours doesn't have ball bearing fingers, so a smooth surface on the work and adequate lubrication are essential. The thumbscrews can only tighten the fingers, so for small adjustments outwards you need to either slack off the clamping nuts or ease them slightly and use a drift against the back of the finger's slot. Once set, check the chuck still turns freely.<br />
<br />
The traveling steady rest needs to run on a machined surface, so at least for the first pass, must follow the tool, so its difficult to avoid using more compound slide overhang than is desirable. An initial surface should be cut next to the chuck or tailstock center before fitting the steady rest.<br />
<br />
Both are a PITA to fit - the fixed one has to have its clamping post inserted up through the bed, and the supplied spanner is useless near the headstock, and the travelling one's mounting holes on the saddle almost invariably need swarf picked out of them.<br />
<br />
==== Turning Between Centers ====<br />
<s>Using a MT3 to MT2 reducing sleeve, the MT2 dead center can be fitted in the spindle.</s> ''Currently the MT3 spindle taper is compromised.'' Alternatively, a soft center can be turned immediately before use in the three jaw chuck, but that must have its 60° point re-cut to concentric if the chuck is disturbed, and needs to be either large enough to bear on the chuck body, or must have a lip to bear on the end face of the jaws to take the axial thrust. Recutting the center is a PITA, as the compound angle must be set to 30° anticlockwise, then reset to a true 0° afterwards. Maybe a right-hand 30° end angle zero rake form tool is the answer, or use the carbide insert tool SSKCR0610H06 as a form tool with the toolpost rotated 15° anticlockwise.<br />
<br />
With the MT2 live center in the tailstock quill, this gives us a center either end of the work to hold it.<br />
<br />
We also need a drive dog similar to [https://littlemachineshop.com/products/product_view.php?ProductID=4473&category=1 this], and the corresponding drive post to bolt to the spindle nose. I have some 25mm bore thick wall iron pipe, which should do nicely. Lengths of the dog's straight tail and of the post TBD after I check how much the center protrudes. N.B. its recommended to tie the tail to the post to keep them in contact so they don't slam. ''Currently we will need to drive from the chuck jaws. Possibly use the exterior jaws with a short soft center gripped on the inside end and drive from the highest step.''<br />
<br />
=== Drilling ===<br />
Always start with a center drill so deflection of longer bits doesn't start the hole off-center. For larger bits (> 5 mm), first drill to the web size, then to final diameter. For a precision hole, drill slightly undersize and ream to final diameter. ''Supply your own reamers!''<br />
<br />
Caution: See note about the quill anti-rotation pin in section [[#Tailstock Quill|Tailstock Quill]] above.<br />
<br />
=== Boring ===<br />
Caution: As the spindle doesn't extend right through the headstock housing, if boring in a through hole, chips tend to fall out the back and tumble in the spindle bore till they fall into the change gears. To avoid this, one should plug the spindle bore with a wad of paper towel or rag and when cleaning up afterwards, use a rod to push it through towards the tailstock, with the chuck jaws (if fitted) wound clear of the spindle bore.<br />
<br />
A swivel bladed hole deburring tool (pale blue handle) can be found in the main room on the windowsill behind the drill press.<br />
<br />
A couple of boring jobs have been bodged with an awkwardly angled turning tool and achieving acceptable effective rake with enough clearance to reach deep enough into the hole has been problematic. I reviewed the tools we had and found none suitable for starting out in a 13mm bore, the max diameter we can (easily) drill. I therefore decided to buy a set of boring bars and make a holder for them. I had difficulty finding anything affordable under 10mm shank - the best low cost option was a [https://www.amazon.co.uk/dp/B07P5LGVBX set of nine 3/8" (9.525 mm) shank brazed carbide tipped boring bars], which would be close to the max capacity of the quick change boring bar holder - if we had one! Unfortunately this holder for our specific toolpost is difficult to find except in a toolpost bundle. Another annoyance is the variable tip height of the set, varying from 1.8 mm to 2.8 mm above the center of the shank.<br />
<br />
I therefore decided to make a boring bar holder of the [https://littlemachineshop.com/products/product_view.php?ProductID=1700 Littlemachineshop.com (USA) style] for use in the four way toolpost, as the additional rigidity will certainly help. Starting with a slightly over 50 mm length of 16 mm aluminium square bar and using the four jaw chuck , both ends were faced and an attempt was made to find its center and center drill it. It was then drilled out to ~9.8 mm after much drama due to blunt drills and drills that cut ~1mm oversize. Too big, but beggars cant be choosers as we didn't have a boring bar holder or a 3/8" reamer. Unfortunately the final hole ended up significantly off center. It was then chucked crossways and ~1 mm skimmed off its thickest side to gain clearance to allow it to be shimmed to height, then one side was slit lengthwise manually with a hacksaw.<br />
<br />
It was fitted to the for way toolpost and loaded with a booring bar, which clamped firmly. A 0.86 mm shim stack brought the tip of the largest boring bar almost spot on center height, with the difference easily accommodated by twisting the tool slightly. The three jaw chuck was then remounted, and a piece of iron pipe chucked for a test. It cuts well and leaves a decent surface finish.<br />
<br />
''The boring bar setup is a work in progress - talk to me before attempting to use them if you have a project that would benefit from boring..''<br />
<br />
ToDo: get something that can sharpen tools tipped with this grade of carbide - it needs some sort of diamond (or possibly CBN) wheel as green grit silicon carbide does little more than polish it. ''N.B. diamond wheels are rapidly eroded by grinding steel, so the supporting steel seat must be undercut with a regular grinding wheel before the diamond wheel can contact it.'' <br />
<br />
We'll also need 50 mm square sheet shims to fit under the toolpost to gain clearance in the toolpost above the tool or toolholder. A 2.4 mm shim would give us about the same above and below spindle center height, and we probably need a small selection of thinner ones.<br />
<br />
=== Thread Cutting ===<br />
The objective is to cut a thread that complies with the ISO metric thread profile. Our lathe is not currently equipped to cut non-metric threads, (with the exception of BA which have pitches based on metric threads of that era).<br />
<br />
[[File:ISO and UTS Thread Dimensions.svg|frame|center|Metric Thread Profile - from the geometry, H is ~86.6% of P]]<br />
<br />
Metric thread data - See 'Preferred Sizes' at: https://en.wikipedia.org/wiki/ISO_metric_screw_thread<br />
<br />
See "Mini Lathe User’s Guide" section '''Threading''' for general techniques *ONLY*, and above for change gears and threading dial setup.<br />
<br />
Amadeal specify the max. thread pitch as 2.5 mm. Any thread pitch greater than 1.5 nn requires the change gears to gear up. When gearing up it is desirable to distribute the ratio as evenly as possible over the two pairs of gears in the geartrain to avoid excessive tooth loading.<br />
<br />
==== External Threading ====<br />
Initially turn work to required Major Diameter, set up change gears and threading tool, touch off on the work, zero the top and cross slide dials, and do a 'scratch' pass to check the pitch. Back off the tool, return the carriage, and re-engage the half nuts on a valid dial line clear of the end of the thread then immediately stop the lathe, and hand turn the chuck till the tool tip is (hopefully) over the scratch to check the thread pickup. If all is good, return the carriage again, restart the lathe and start cutting your thread. <br />
<br />
Methods of doing so vary depending on the size of the thread and toughness of the metal, but straight-in plunge cutting is generally to be avoided as has the highest cutting forces, and does not reliably keep the carriage (and top-slide if set parallel to the work) loaded to avoid pitch errors due to backlash. <br />
<br />
If leaving the half-nuts engaged and reversing the lathe to return to the start of the thread for the next pass, its absolutely essential to back the tool out of the thread for the return pass as it will not follow the path of the cutting pass due to backlash in the geartrain, leadscrew mounts and half-nuts.<br />
<br />
==== Internal Threading ====<br />
''<nothing here yet>''<br />
<br />
== Cutting fluids ==<br />
=== Why bother? ===<br />
[https://youtu.be/mRuSYQ5Npek Watch this video] and contemplate what's actually happening to that thin ribbon of metal being removed. Most of the lathe's motor power is being turned into heat by internal friction in the chip being removed in the zone around the cutting edge, and surface friction at, and immediately behind the cutting edge, near-instantly heating the chip by up to several hundred degrees. Reducing the surface friction using a suitable cutting oil reduces the strain on the machine as a whole, and reduces workpiece and tool heating (and thus expansion) with consequent improvements in maximum usable feed and depth of cut, surface finish and accuracy. It also drastically increases the life of the cutting edge.<br />
<br />
=== Practicalities === <br />
We don't have a coolant system for the lathe and *really* don't want the maintenance hassles of using soluble cutting oil/coolant as if used infrequently its a PITA to keep recirculated high water content cutting fluids from going rancid and stinky, and they can also rust the ways, so even a total loss gravity feed system is problematic. Therefore if dry machining doesn't give a good enough finish, we tend to use oil applied topically, by hand to the work. <br />
<br />
* Hard brass is typically free-turning without oil, however some light oil for the final cut can improve surface finish, but with the disadvantage that it will increase loose chip buildup on the tool as hard brass typically forms short spalls or splinters rather than curly chips.<br />
<br />
* Many Aluminium alloys tend to be gummy, and Paraffin or other mineral spirits mixed with a little oil can help prevent the aluminum welding to the tool edge. WD40 will do at a pinch, but its messy to apply from a spray can.<br />
<br />
* Steel really needs *GOOD* cutting oil. Lard oil is the traditional choice for steel. If there are any objections to lard oil, we should bite the bullet and get some commercial dark high Sulphur cutting oil, but beware, many such oils use an additive package that includes lard oil.<br />
* Cast iron (except ductile) should be cut dry, as the carbon micro-inclusions self-lubricate it, and the carbide in the dust (primarily Cementite) are very abrasive, so tend to form a grinding compound if mixed with oil. <br />
<br />
I've sorted out an oil pot lid with a 1/2" brass collar soldered in to give a nice smooth sided hole, for ease of use and to minimize the risk of spills when using a brush to apply cutting oils, and got some dirt-cheap brushes. It fits Shippam's paste (and similar own-brand spread) jars and I've found several jars and ordinary lids to seal them for storage. Unfortunately it isn't the easiest to get this type of jars' lids back on square so they seal properly, and if you over-tighten them and there's a temperature change, they can be a total <expletive> to reopen. Using the rubberised handles of a large pair of pliers to grip the jar lid just above its rim is the best option, and avoids damaging the lids.<br />
<br />
''N.B. For the smaller brushes, the glue holding the bristles in is attacked by paraffin. To prevent loss of bristles, crimp the aluminium ferrule of each new brush of this type before use.''<br />
<br />
We have, in labelled jars:<br />
<br />
* Sulphurised Lard oil thinned with paraffin. Best choice for heavy cuts and threading in steel but stinky.<br />
* Lard oil thinned with paraffin. Good for steel and acceptable for softer copper alloys<br />
* Paraffin with a trace of light oil. Good for aluminium, and can help prevent squealing chatter on finish cuts in brass.<br />
<br />
I've also got some paraffin wax (in the form of a stubby candle), which can be applied lightly (under power) to brass and aluminium stock especially on the finish pass. It makes less mess than oil but unfortunately tends to build up on the tool tip, making it difficult to 'work by eye' without frequent pauses to clean the tool tip.<br />
<br />
We've also got a tin of [https://www.rocol.com/products/rtd-compound Rocol RTD cutting compound], which is a thick paste. Its highly recommended for drilling and tapping steel (in the drill press or by hand), but as a paste, is less useful for general lathe work unless thinned to a fluid consistency, e.g. with paraffin or white spirits. OTOH its certainly worth trying for high speed facing steel as it is less likely to get flung off.<br />
<br />
== Cleaning and Maintenance ==<br />
Swarf is a significant cut hazard to the operator, especially stringy swarf from cutting steel. Never touch it bare-handed - always use a tool e.g. a brush, or a hook, or needle nose pliers for grabbing long swarf.<br />
<br />
* After use, brush all swarf off the toolholder, compound and cross slide etc. ways and leadscrew. Ian B has blocked off the opening at the headstock end of the rear splashguard (to try to keep swarf out of the motor), so one must sweep the swarf towards the open tailstock end and catch it in a dustpan or similar. Preferably, also thoroughly clean out the chip tray under the lathe, but at least sweep out visible swarf.<br />
* Wipe up any cutting fluid residue and re-lubricate affected sliding surfaces with way oil.<br />
* Do not solvent clean the chuck guard, as it will make the plastic brittle, or even craze it. Water with a little detergent is permissible for cleaning it, with the guard totally removed from the lathe.<br />
<br />
Before engaging the half-nuts for power feed/threading, check the leadscrew is clean! ''Best cleaned under power, with a toothbrush.'' <br />
<br />
'''Caution:''' The traverse gears behind the carriage handwheel are in an open-backed housing and tend to become packed with swarf! Swarf buildup here will result in jerky carriage movement. Clean out as much as you can with a toothbrush ...<br />
<br />
===Lack of lubrication and/or swarf or dirt build-up can be disastrous===<br />
* If using the change gears/power feed, lack of lubrication of the B-C stub shaft center pin or either leadscrew end bearing can result in seizure and immediate destruction of one or more gears in the gear train or worse. <br />
* Small pieces of swarf can get between the saddle and ways, or into the slides degrading accuracy, possibly permanently if hard swarf scores them, or jamming them. The carriage handwheel gears behind the apron are notorious for accumulating swarf, and swarf buildup on the leadscrew can prevent the half-nuts engaging properly, resulting in scrapped work, and possibly stripped half-nuts. <br />
* Metal swarf can get into the motor (''though Ian B has modified the rear chip catcher to reduce the risk)'' or into the control box via the leadscrew, and short-circuit stuff. At best it will blow the fuse and need a strip-down to clean it out, at worst it may require a replacement [https://www.amadeal.co.uk/acatalog/Speed-Control-Circuit-Board--12amp-AMA_SP_CJ18_SCB12.html#SID=12 speed controller] ''(currently £96)'' and/or [https://www.amadeal.co.uk/acatalog/550W-motor-for-CJ18A-Mini-Lathe-467.html#SID=240 motor] ''(currently £105)'' and possibly other electrical parts. We should probably fit a [https://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C3-Mini-Lathe-Spares/C3-256-Leadscrew-Grommet-Dustproof-Cover C3-256 Leadscrew Grommet] to keep swarf out of the control box, as it tends to drop onto the 'Filter' board which is mounted horizontally, below the leadscrew.<br />
* Grit from grinding, sanding etc. forms a grinding paste with the way oil, and will rapidly wear out the ways, saddle and slides. Keep grit off at all costs e.g. by covering the ways and slides during grinding/sanding operations, and if there's any chance grit has gotten where it shouldn't, clean and re-lubricate *BEFORE* moving the carriage or slides, then move the carriage and slides, wipe down where they were with a clean paper towel and check there's no remaining traces of dirt other than clean way oil on the paper towel. If it doesn't come clean when you re-lubricate and move it again, a full strip down may be required to solvent clean and relubricate the precision sliding surfaces.<br />
* Although a metalworking lathe *can* be used to turn hardwood, wood dust and small chips are extremely pernicious, as they get everywhere, even clinging to clean surfaces, are abrasive due to their silica content, and are hygroscopic, promoting rust. An even more thorough clean-up than after using abrasives is needed, immediately afterwards. Oily wood dust and fine wood chips in significant quantities are a fire hazard, even in the trash bin.<br />
<br />
===Lubrication===<br />
See section: "Lubrication" in LittleMachineShop.com "Mini Lathe User’s Guide" [[Ian_M's_Lathe_Notes#Manuals|(below)]]. As we usually only open two nights a week, in the table on page 16, Daily lubrication becomes Weekly and Weekly becomes Monthly.<br />
<br />
===General Maintenance===<br />
* The grubscrews holding the cross-slide and compound slide dials tend to loosen due to vibration and use of the dials. Keep them snugged up, but not so tight the dials cant be set without an Allen key.<br />
<br />
* The screws holding the cross-slide nut tend to work loose due to vibration. Crank the handle to and fro through the backlash and visually check there is no movement of the screw heads in their holes. If there is, see the [[#Excessive_cross-slide_backlash|notes below]].<br />
<br />
===Removing the Carriage===<br />
Its possible to remove the carriage from the bed for cleaning etc. without dismantling it. The only stop to its motion is the righthand leadscrew bearing.<br />
<br />
Start by removing the tailstock. Crank the carriage to the tailstock end then remove the leadscrew bearing (two screws and a nyloc nut on the leadscrew end). With the half-nuts open, hold the leadscrew centered in them and crank the carriage off the end of its rack, then slide it off the end of the bed.<br />
<br />
Refitting is the reverse of removal, except (if its gibs are correctly adjusted) the carriage will be very tight on the end of the bed ways so may be difficult to work onto the ways without a stack of blocks of wood or similar to support it at exactly the right height. The righthand leadscrew bearing must be refitted with the carriage as close as possible to it and the half-nuts firmly closed to support the leadscrew at the correct height to hold it in alignment while the screws are being tightened. The nyloc nut controls leadscrew end-play. Fully tighten it then back it off slightly till the leadscrew turns freely with its change gear removed.<br />
<br />
If the Apron has been off, refit it with the screws no more than lightly finger tight and only finally tighten them after checking lead screw engagement at both ends of the carriage travel and that the rack and pinion operates smoothly over the full travel.<br />
<br />
== Issues and Annoyances ==<br />
As of September 2023 - mostly resolved, apart from the spindle bearings and runout, the lathe is in better condition than it has been for a number of years.<br />
<br />
===Four Jaw Chuck has two jaws too tight===<br />
Fixed 27/10/2023: Two of the chuck jaws were tight in their slots, making precise adjustment difficult due to lack of 'feel'. Moving the jaws round the slots showed the problem mostly followed the jaw not the slot. The grooves in the opposite sides of the affected jaws that run in the chuck slots were slightly out of true, and the rails either side of the slots were slightly too thick towards the center. Due to the difficulty of seeing the high spots, after cleaning up and deburring the jaws didn't do enough to ease them, I decided to grind the top of the rails where they were binding. Several repetitions of spotting with Engineer's blue, grinding, then diamond filing the high spots has eased them enough. I cleaned everything, greased the jaw slides and screws, and refitted the studs so the chuck is now fit for service.<br />
<br />
''N.B. Don't move the jaws to a different slot - the formerly tight jaws *must* stay in the slots furthest from the makers mark.''<br />
<br />
===Excessive Runout===<br />
Mostly fixed 24/10/2022: I ground the chuck seating surface of the spindle nose (outside lip) to under half a thou runout. This also cleaned up several burrs. It would be possible to do better, but that would need good spindle bearings, and a more rigid toolpost grinder mount.<br />
<br />
Our spindle nose was damaged years ago by a person with little mechanical aptitude (who shall remain nameless) beating it up with a hammer mushrooming the spindle nose. We are getting several thousandths runout at the end of the MT3 bore, a MT3 to MT2 reducer sleeve in it runs visibly out of true, as does the spindle nose flange. When you put a chuck on it, the runout is magnified by the distance from the spindle nose. Ideally we would replace the spindle when we change the bearings but its £52 [https://www.amadeal.co.uk/acatalog/4-Spindle-Upgrade-Real-Bull-Mini-lathe-CJ18-series-AMA_SP_CJ18_003RB.html#SID=9 from Amadeal] and money is tight. It may well require more work after the bearing upgrade. Once good bearings are in, if we can borrow a decent MT3 arbour as a reference, we should consider skimming the bore.<br />
<br />
===Spindle bearings===<br />
* The spindle bearings appear to be close to worn out. They are notably noisy when running, and there appears to be more slop in the spindle than is desirable. There is notable resonance around 600 RPM, and surface finish of end faces is often poor. We have some ideas for possible replacement/upgrade, but it requires a major teardown.<br />
<br />
: The original bearings are allegedly 6206-2RS or 6206-ZZ deep groove ball bearings - 2RS codes rubber seals both sides and ZZ codes metal shields. Although the deep groove gives reasonable ability to withstand axial loads, the bearing balls point contact means they are vulnerable to [https://en.wikipedia.org/wiki/Brinelling brinelling] due to shock loading. The jammed on three jaw chuck didn't help this, as before we skimmed the spindle nose lip, it had to be driven off using a bar through the spindle bore, shock loading the bearings every time. Also even a minor 'crash' could have brinelled them due to eccentric shock loading, and the lathe has previously been crashed badly enough to need drive gear replacement. There are also issues with the 'approved' method of spindle and bearing removal from the headstock brinelling them, even if you don't abuse the spindle nose with a hammer!<br />
<br />
: A possible replacement is 30206 tapered roller bearings. The new bearings are slightly thicker so the plastic spindle spacer (15) needs to be machined to length to get the 45 tooth spur gear that drives the change gears laterally aligned with the tumbler gears. If a temporary replacement (3D printed?) is fitted, the lathe can be run (without power feed capability) so this can be done on the lathe after fitting the new bearings. As tapered roller bearings have line contact, they are significantly more resistant to brinelling.<br />
<br />
: ''See [[Talk:Ian_M%27s_Lathe_Notes]] for notes, links etc. for this upgrade.''<br />
<br />
===Motor stuttering===<br />
* Fixed 21/09/2023: The motor was running very erratically and it was very difficult to set a speed. Several loose connections were found in the control box, mostly loose female spades to the motor controller board, but also a dry jointed braking resistor on the 'Filter' board, and an inhibit wire completely off its terminal on the forward/reverse switch, making intermittent contact. After tightening and/or remaking all affected connections, it was much improved but still not right below 300 RPM. The remaining issues were due to poor wiper contact in the speed control pot, and stripping it, cleaning the track and contact ring and re-tensioning the contacts resulted in the motor now running smoothly over the full speed range. The speed is slow to settle, and while part of that is probably the lag in the digital tach, I suspect that the KBIC motor speed controller isn't properly tuned as it was (allegedly) previously replaced.<br />
<br />
===Drive belt slipping===<br />
* Fixed 28/9/2022: During testing the motor after the above issue, it was noted that the chuck could be stalled, slipping the drive belt, with not much torque. The drive belt was determined to be loose and a bit worn, but still in acceptable condition. <br />
<br />
: Access for servicing the belt requires removing the control box ''(2 spades to ZVR switch disconnect the supply, speed sensor and motor simply unplug from the 'filter board')'', the motor cover, chuck guard switch assembly + wiring cover, the change gear 'A' (drive) shaft carrier assembly, and the tumbler gear assembly. See https://youtu.be/EkxlIz01BdA for disassembly/reassembly, though on our lathe, the speed encoder ring on the spindle prevents the belt cover from being fully removed without disturbing the spindle nuts. There is enough room to work with it loose, but still trapped by the encoder ring. Also, unlike the video, if the 'jack' screws under the headstock are correctly adjusted, and the studs aren't excessively bent, there is no need to make custom studs. <br />
<br />
: It turns out that our lathe was missing the M6 hex headed jack screws that press the motor down to resist the belt tension, and the motor had cocked out of position at a severe angle. I know Ian B had had considerable trouble adjusting it after the motor fault back in October 2022, and I believe it had been getting slowly worse ever since. The jack screws were probably mistaken for headstock fixing bolts during disassembly after the crash that resulted in the metal Hi/Lo gears being fitted, then lost. The penny washers on the studs had dished, so I turned them over and backed them up with smaller washers and switched to Nyloc nuts so they cant back off due to vibration. N.B. There is a packing washer on the motor side on one of the studs, presumably so the shaft is true to the ways. Adjusting the motor is awkward to say the least. One has to slack the stud nuts off a lot, pry under its rear end to lift it enough to be parallel to the ways, snug the stud nuts, check alignment, then set the jack screws and their lock nuts to hold it there, and finally tighten the stud nuts. <br />
<br />
: Tension: According to Sieg, it should be possible to twist the belt 90° mid span with a light finger grip. Other sources say 1/32" - 3/32" deflection mid span with light finger pressure.<br />
<br />
===Speed display blanking===<br />
* The speed display has been intermittent, blanking and flashing 8888 and 0 at certain speeds for as long as I have been using the lathe. Finally on 18/07/2022 it failed completely, with no display. I removed the display module and bench tested it - the pins are labelled 5V GND PL PE, PE is frame ground and PL is a TTL level pulse from the speed sensor - confirming that it was in good working order. My suspicions then turned to its power supply on the 'Filter' board. With both the sensor and display unplugged, the 5V rail was found to have a only a couple of volts, but the unreg DC was 17V and stable. Replacing the 78L05 5V regulator restored the 5V rail and normal operation.<br />
<br />
: ''I conclude its been failing for a while with high load current due to speeds with more lit segments causing it to drop out, resetting the speed display, causing it to blank, lowering the current enough for the regulator to recover, then the display MCU lamp tests (8888) then re-acquires the speed, repeating ad-nauseum till the speed is changed. I don't like the design as the high input voltage results in excessive dissipation.'' <br />
<br />
: ''ToDo: If it fails again, bench test display to measure its worst case current consumption, then fit an appropriate dropper resistor to reduce the 78L05 dissipation.''<br />
<br />
===Quill spinning when drilling===<br />
* The quill was tending to spin while drilling because its anti-rotation pin (a M5 dog tip setscrew) was sheered. I've removed the debris, aligned the scale with the top of the tailstock and fitted a longer M5 dog-tip setscrew to replace it, with a nut to lock it at the correct height. N.B. the pin isn't that 'meaty' so if using big drills in tough metals, to prevent shearing it, it should be backed out so the quill can be turned by hand and unwanted rotation controlled by being quick with the quill lock if it starts to spin, or even using a close fitting rod in one of the chuck key holes with plastic tube over it to protect the ways. <br />
: ''If the screw sheers again, the quill will need to be removed and the tailstock taken off the lathe so the sheered tip can be shaken out, and if the setscrew is difficult to remove it probably means the threads are mangled where it sheered. Try driving it right through with the quill out.''<br />
<br />
===Sloppy quick change toolpost locking mechanism===<br />
* Once the dovetail clamp screw was slackened, there was nothing preventing the dovetail twisting or cocking significantly, and friction with the toolholder made it tend to do so, making toolholder insertion and removal more difficult unless the clamping screw was backed off excessively. I added a compression spring around the clamp screw inside the toolpost to push the dovetail outwards so it mostly retains alignment when open, allowing toolholders to slide on or off cleanly with far less screw slackening.<br />
<br />
===Leadscrew rubbing===<br />
* The leadscrew shaft is rubbing on the insulating separator inside the control box. Unfortunately the corner of the relay on the Filter Control Board (#160) doesn't allow enough clearance. Although the friction isn't much of a problem at high reduction ratios, e.g. 16:1 power feed, it increases the stress on the change gear train, and may be problematic when threading at feeds above 1:1. ''Possibly pack out the control box mountings by a couple of mm.'' <br />
<br />
===High/Low lever backwards!===<br />
* The high-low drive gear selector behind the headstock is incorrectly labelled and differs from the manual: low gear (which we normally use) is with the lever towards the tailstock. ''I suspect that the gears in the headstock were refitted the wrong way round when it was upgraded to metal gears.''<br />
<br />
: ''ToDo: Get it reassembled the right way round during the spindle bearing upgrade!''<br />
<br />
===Carriage lock fouls top slide===<br />
* The T handscrew has been replaced with a M5 hex headed bolt, to permit access when the top slide is over it. An 1/4" drive 8mm socket is usually left on it, but needs to be removed when the full cross slide travel is needed. The small (4 jaw) chuck key is near enough 1/4" to use for it. If you need to (un)lock it while the compound is over it, you'll need an 8mm spanner. ''The [https://www.amadeal.co.uk/acatalog/Mini-Lathe-Carriage-Lock-463.html Amadeal lock screw] is in the spares tin as it was too high and fouled the compound slide.''<br />
<br />
===Tailstock locking lever loose===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock - See full image for key to screws]]<br />
* Diagnosed and fixed 10/1/2023 - In the base of the upper section of the tailstock, there are two dog tip set screws that engage with locating grooves in the counter-rotating shafts carrying the eccentric locking cams. They'd backed off, probably due to vibration. They need to be tightened till they bottom out in the groove, making sure they are '''in''' the groove, backed off half a turn so the shafts can turn easily, and locked in place. There's no facility to do so, so reassemble with weak threadlocker. Unfortunately to get to them you have to remove the tailstock base slide, which is held on by the pressure of four adjusting grub screws, which all need backing off, and one socket headed bolt from underneath so full tailstock realignment is required after reassembly, which even for a rough alignment is tedious.<br />
: <s>The tailstock locking lever is loose and can be pulled out on its axis. It works OK when fully pushed home but needs investigating. ''I tightened the grub screw as the lever was coming off its shaft, but the whole shaft pushes/pulls in and out. It works OK fully pushed in, but it seems something that is meant to retain it has failed inside the tailstock base.</s><br />
<br />
===Gear alignment issues===<br />
* Change gear alignment is poor. I've currently got a gapped washer (to clear the key) packing out the A shaft so the gears line up, but this reduces the key's engagement so is problematic due to the high loading if the gears are set up for coarser threads. <s>Also I need to turn down some penny washers to slightly less than the root diameter of the metal 20T pinions, as gear retaining washers.</s> ''The gear retaining washers for A gear and B-C stub shaft are now done, turned down to slightly under 16 mm dia. Spares in the change gear tin. ToDo: The D (leadscrew) washer requires a larger center hole, so make two more with that hole.'' <br />
<br />
===Saddle gibs loose===<br />
* Fixed 11/04/2023: I took the apron off for access (and to clean the carriage handwheel gears), and found the front sheer plate screws were completely loose. I've snugged them up some and set the opposing grub screws and got a lot of the slop out. I've re-checked the front ones, and taken up the slop in the rear ones - Unfortunately it wasn't possible to get carriage movement to have an even 'feel' over its whole travel, and its noticeably tighter near the tailstock. If light hand pressure on the side of the unlocked carriage can cause movement (with the half-nuts open), its time to readjust them again, though it should be possible to move the carriage with a firm push. <s>The saddle gibs (actually the sheer plates) were too loose, to the point that engaging a slightly stiff threading dial could cause it to self-feed, an obvious crash hazard if working near the chuck or a step in the work.</s><br />
<br />
''N.B. the lefthand front opposing grubscrew is short, (fully recessed) and unlike the others does *NOT* have a locking nut as it must clear the traverse pinion. A wrap of PTFE tape provides enough friction to keep it in place, though possibly a bit of nylon fishing line down its hole would be better.''<br />
<br />
===Excessive cross-slide backlash===<br />
* ''Fixed 21/11/2023.'' Originally, back in October 2023, The cross-slide screw had excessive backlash (nearly three turns), which increases the risk of loosing track of the cut depth when cutting steps, and during threading operations. If you ended up off by a turn too far in, a crash would be the most likely outcome.<br />
: The original excessive backlash was traced to loose cross-slide screw nut mountings. The nut has two socket headed cap screws pulling up, one either end, accessible from the top of the cross-slide, which control the tilt of the nut to take up backlash in the nut, and an opposing grub screw pressing down on the center of the nut to make it longitudinally rigid. Snugging up the grub screw reduced the backlash to 10 divisions or so, or 0.25 mm. A year later, the backlash had increased to one turn due to the cross-slide nut mounting screws working loose again.<br />
<br />
: 07/11/2023: I investigated further: It is difficult to get the cross-slide nut aligned correctly as it must be at the same height as the screw which is constrained by the bearing surfaces in the bracket. With the cross-slide almost at the front limit of its travel, I removed the screw and set the nut as level as possible and visually centered in the bore, then re-fitted the bracket and screw, then adjusted the tilt till it turned freely through the backlash. I then tilted it up at the front till some drag was felt to minimise the backlash and tightened the screws to lock it in place balancing them to maintain the same feel as I tightened them. The result was 7 divisions of backlash, acceptable but not great. During normal turning operations, the load on the nut is tension on the front screw and pressure on the grubscrew, so if it slackens again due to vibration from chatter, odds are it will be the rear screw that's loosened.<br />
<br />
: 16/11/2023 - 21/11/2023: The backlash had crept back up to 11 divisions (0.275 mm). We don't have any >14 mm brass stock (or even near that) so I tried making the shim washer out of aluminium. I was shooting for 0.24 mm but due to poor technique got 0.28 mm. No good - locked solid. I lapped it down and tried it till I got it down to 0.20 mm which gave about 3 divisions backlash - good enough, but the screw was too tight due to the shim washer not being bevelled at its outer edge resulting in it cupping in its seat. Filing a bevel round the OD and re-lapping it resulted in a 3 - 4 divisions of backlash. Its a little mushy due to the washer having been kinked removing it, so ideally a new (brass) washer should be made. <br />
<br />
* Further reduction of backlash: https://youtu.be/Wu_tI29JL2Y?t=163 <br />
: Brass tinned with Pb-free solder to form a white metal bearing surface should work at least as well as the bronze used in the video. The shim washer needs to be 10.2mm ID, with a full thickness bevel on a 14 mm OD. It isn't necessary to remove the lead screw from the cross slide, as the washer can be fitted in-situ with only the bracket removed.<br />
<br />
===3 Jaw chuck didn't mount properly===<br />
* Fixed 7/4/2023 by grinding the spindle nose lip. The three jaw chuck can now be installed and removed by hand with no hammering. A test bar in it now has only 2 thou runout (TIR) at the chuck.<br />
: <s>The three jaw chuck and the faceplate aren't seating properly on the spindle nose. Its too tight on the register diameter of the lip. This results in grossly excessive runout, and also makes this chuck and the faceplate a PITA to fit or remove.</s><br />
: ''The spindle nose had been abused with a hammer (before my time) which mushroomed it and may have brinelled its bearings. See '''Excessive Runout''' and '''Spindle bearings''' above.''<br />
<br />
== Manuals, Books and other resources ==<br />
=== Manuals ===<br />
The [https://wiki.richmondmakerlabs.uk/images/a/a3/Lathe_InductionNotes.pdf RML CJ18A Mini-Lathe Induction Notes]. Your mandatory Lathe Induction will cover most of this but its good to be able to refer back to it.<br />
<br />
Official [https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Amadeal CJ18A Manual], or paper copy (less complete) kept on shelf above lathe.<br />
<br />
The [https://www.chesterhobbystore.com/wp-content/uploads/2022/11/Conquest-Super-Lathe.pdf Conquest Super Lathe manual] is considerably better than the Amadeal manual and is for a near-identical machine.<br />
<br />
The [https://littlemachineshop.com/images/gallery/info/minilatheusersguide.pdf Mini Lathe User’s Guide] from LittleMachineShop.com is even more comprehensive, going into its usage in some detail, with a proper TOC, and covers both US and Metric versions of Realbull Mini-lathes. ''The only fly in the ointment is the threading section assumes a US lead screw so change gear selections and threading dial divisions will not be correct for our lathe.''<br />
<br />
[https://www.arceurotrade.co.uk/machineguides/C3-Mini-Lathe-Dismantling-and-Reassembly-Guide.pdf Sieg C3 Mini-lathe Dismantling and Reassembly Guide] "A picture story book to help you dismantle and reassemble your Sieg C3 Mini-Lathe" ''It is similar enough to ours to serve as a maintenance guide, except for the electronics, spindle drive and other headstock innards.<br />
<br />
The motor controller is a clone of a [https://acim.nidec.com/drives/kbelectronics/-/media/kbelectronics/documents/dc-drives/manuals/kbic_manual.ashx?la=en KBIC® SCR DC Motor Speed Control]<br />
<br />
=== Books ===<br />
'''Metal Turning on the Lathe''', by David A Clark, Crowood Metalworking Guides, ISBN-13: 978-1847975232 [https://www.amazon.co.uk/gp/product/B00E78RKIG Kindle Edition (£8.99)]. ''A 'free' epub can be googled for, *NOT* linked here due to dubious legality.''<br />
<br />
'''[https://archive.org/details/03screwcuttinginthelathe Screwcutting In The Lathe]''', by Martin Cleeve (a pen-name of Kenneth C Hart), Workshop Practice series #3, ISBN-13: 9780852428382<br />
<br />
'''[https://archive.org/details/15workholdinginthelathe Workholding in the Lathe]''', by 'Tubal Cain' (a pen-name of Tom Walsh), Workshop Practice series #15, Argus Books, ISBN-10: 0852429088<br />
<br />
'''[https://archive.org/details/20metalworkandmachininghintsandtips Metalwork and Machining Hints and Tips]''', by Ian Bradley, Workshop Practice series #20, ISBN-13: 9780852429471<br />
<br />
'''[https://archive.org/details/38toolandcuttersharpening Tool and Cutter Sharpening]''', by Harold Hall, Workshop Practice series #38, ISBN-13: 9781854862419<br />
<br />
'''[https://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpaperT204.pdf Cutting Fluids]''', by EC Bingham, NIST Tech. Paper No. 204, 1921<br />
<br />
=== WWW resources ===<br />
==== Mini-lathe Specific ====<br />
There's a *LOT* of mini-lathe info online. Notable sites include:<br />
* http://www.mini-lathe.com/ - A major Realbull/Sieg mini-lathe resource.<br />
* http://mikesworkshop.weebly.com/lathe-modifications.html - many mods including carriage DRO autostop, and variable speed leadscrew motor drive, cross-slide motor drive, etc. He also has a page with a bunch of accessories, toolholders etc. - http://mikesworkshop.weebly.com/lathe-accessories-and-tooling.html<br />
* http://andysmachines.weebly.com/variable-speed-controls.html - Scroll down to the 'UPDATE' section for the schematic of a very similar SCR speed control board. It also has the schematic for an earlier version of the Auxiliary Control Board (aka: 'Filter' board).<br />
<br />
==== Forums ====<br />
''with publicly accessible archives''<br />
* https://groups.io/g/7x12MiniLathe - Mini-lathe specific, active<br />
* https://www.hobby-machinist.com/forums/mini-lathe-mini-mill-information.220/ - active<br />
==== Youtube Playlists & Videos ====<br />
* Blondihacks: [https://www.youtube.com/playlist?list=PLY67-4BrEae9Ad91LPRIhcLJM9fO-HJyN Lathe Skills] (playlist) - "This is an educational series to help you learn to use your metal lathe. Watch them in order for best results! Satisfaction not guaranteed, especially if you're a cranky sort of person."<br />
* Frank Hoose (Minilathe.com) has a couple of relevant Youtube playlists:<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn7ON0jGM5UbM-KZDT56MOIp Mini Lathe Operations]<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn4nGRZaVq3wTOlvZNOmdAZ2 Mini Lathe Overview]<br />
<br />
==== General Machining ====<br />
* https://www.machiningdoctor.com/ - "THE #1 MACHINING TECHNICAL HUB"<br />
<br />
==Projects==<br />
[[File:VESA mount.jpg|thumb|Machined VESA mounting plate (left) and plate from Dell monitor stand it must match (right). The translucent washer shows the size of the original center hole.]]<br />
* My first faceplate project was boring out the center hole in a VESA mounting plate to adapt it to fit onto a surplus Dell 1708FP monitor stand. The part was centered using the tailstock dead center engaging with its original center hole. I clamped the part with studs and penny washers on the driving side of two opposite corners, with cap screws in the next slot round to trap the corners under the clamping washers, then withdrew the tailstock and dead center. After machining out the bore, I used the tip of the tool, rotating the chuck by hand, to scribe a circle for laying out the bolt holes. I finished off laying out and drilling the bolt and locating holes by hand at home, fitted it to the stand, and mounted the 2nd hand LG 24" widescreen monitor.<br />
<br />
* Another ultimately unsuccessful project was fly cutting aluminum flat bar to thickness to make custom shims for the set of carbide insert tools, for the four way toolpost. The 8 mm shank tools need ~2.5 mm shim stacks, and the 6 mm shank tools need ~4.5 mm shim stacks. Ideally I'd machine single shims, but the only stock I've got handy cleans up to only 3.2mm, and some fine shimming may be needed to fine-tune the tool height.<br />
<br />
: After sorting out the clamps so they were no longer twisting the aluminum flat bar stock, and switching to the short 45° turning SCMT06204 insert tool in the four way toolpost, to improve rigidity and get a well controlled tip radius, the finish was much improved. I'm still having problems getting an even thickness and am getting approx. 0.05mm variation, I suspect due to the aluminium bar stock distorting due to internal stresses as its surface is cut away. ''ToDo: try supergluing the stock to the faceplate before clamping to further reduce chatter and stop the warping.''<br />
: Looking back on this project a year later, its fairly obvious that the thickness variation was probably due to faceplate surface runout due to the damaged spindle nose.<br />
<br />
* Raphael has been working on a steel rocket nozzle with some assistance from myself. We have set up the rough cut chunk of ~ 50mm steel bar, faced both ends (to 50mm length) and turned the OD to 49mm to clean it up. Its going to need through drilling, probably some boring, and quite a bit of detail work on the OD. It will then need to be transferred to a jig in the drill press vice to allow a pattern of angled traverse holes to be drilled with acceptable accuracy.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_Lathe_Notes&diff=17613Ian M's Lathe Notes2024-02-07T12:19:12Z<p>IanM: /* Slide Locks */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br />
<br />
''Currently these notes are semi-organized and non-authoritative. As I become more experienced with the RML CJ18A mini-lathe, I'm cleaning up, extending and reorganising them. Some lathe operating experience is assumed. If in doubt, '''*ASK*''' me, Andy H<sup>*</sup> , Jonathan H or another experienced minilathe operator!<br />
<br />
''* Andy H should be asked (for an authoritative answer) any questions involving RML usage policies or acquiring tooling or materials through RML.''<br />
<br />
== The Lathe ==<br />
Our Facilities page [[Facilities#Lathe|has]]:<br />
<blockquote><br />
'''Lathe'''<br />
[[File: Lathe2.jpg |200px|right | Lathe]]<br />
In the kitchen. <br />
<br />
Marked as a CJ18A Mini-Lathe from [[https://www.amadeal.co.uk/acatalog/CJ18A-Mini-Lathe-7x14-Machine-100mm-3jaw-Metric-With-Metal-Gears-AMA_LA_CJ18_M_3_MGRB.html Amadeal]]<br />
[[https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Manual]] <br />
<br />
[[Media:Lathe InductionNotes.pdf| Induction Document]]<br />
<br />
Possible upgrades:<br />
*https://www.youtube.com/watch?v=GwT-JQLbNPA<br />
<br />
''Please do not use the lathe until you have received induction'' <br />
<br clear=all><br />
</blockquote><br />
Its a Chinese import 7x14 mini-lathe. The 7x14 refers to the maximum diameter and length of work, in inches and is only a theoretical measure of the working envelope as you loose length to the chuck + any tailstock tooling, and the diameter is over the bed, not the cross-slide. See actual specifications below. <br />
<br />
Most if not all Chinese 7x10 to 7x16 mini-lathes seem to be remarkably similar (not uncommon with Chinese products due to [https://www.bunniestudios.com/blog/?p=284 Shanzhai (山寨)] )<br />
and the OEM of our Amadeal CJ18A Mini-Lathe was probably [https://www.made-in-china.com/showroom/cheap-lathe Yangzhou Realbull Machinery Co. Ltd]. Very similar lathes are also made by [https://www.siegind.com/lathe-machine.html Sieg], but their lathes tend to be slightly less sophisticated than the equivalent Realbull models.<br />
<br />
''N.B. Many Sieg parts are known to have slight but critical differences from Realbull parts, so '''DON'T''' order Sieg spares for a Realbull lathe!<br />
<br />
== Key Specifications ==<br />
Amadeal says the CJ18A Mini-Lathe is a 7x14 model with:<br />
<blockquote><br />
* Power 550 W<br />
* Distance between centres : 350 mm<br />
* Swing Over Bed: 180 mm<br />
* Swing Over Cross Slide: 110 mm<br />
* Taper: MT3<br />
* Tailstock Taper: MT2<br />
* Chuck diameter: 100 mm<br />
* Spindle Speed: 50 - 2500 rpm ''(with digital readout)''<br />
* Spindle Bore: 20 mm<br />
* Cross slide Travel: 65 mm<br />
* Range of Metric Threads: 0.5 - 2.5mm.<br />
</blockquote><br />
* The lead screw is metric, pitch 1.5 mm.<br />
* The spindle center is 90.6 mm above the flat of the bed (measured).<br />
<br />
Even though the compound and cross slide handwheels appear to be calibrated in thousandths of an inch, as ours is a metric machine, they only approximate that. One turn of a slide handwheel is 1mm advance, and they have 40 divisions, so each division is 0.025 mm, (approx. 0.984 [https://en.wikipedia.org/wiki/Thousandth_of_an_inch thou]). Similarly, the tailstock quill advances 1.25 mm per handwheel turn, which has 50 division dial, giving the same 0.025 mm divisions, but only 4 turns per 5 mm. The carriage handwheel is awkward - it moves approx. 19.2 mm per turn, and doesn't have a dial scale.<br />
<br />
== Notable Accessories ==<br />
We have:<br />
* [https://www.amadeal.co.uk/acatalog/160mm-Face-Plate-for-the-4-Mini-lathe-AMA_AC_CJ18A_FP160RB.html#SID=129 160 mm (6 1/4") Faceplate]<br />
* 100 mm (4") three jaw self-centering chuck (OEM standard) 22.5mm bore, with inside and outside jaw sets<br />
* 100 mm (4") four jaw (independent) chuck with reversible jaws (8 TPI screws)<br />
* Tailstock drill chuck (max. 13 mm dia.)<br />
* Live center for tailstock (+ OEM fixed center) <br />
* Four way Tool Post (OEM Standard)<br />
* [https://www.amadeal.co.uk/acatalog/Quick_Change_Tool_Post_for_the_mini-lathe.html Quick Change Tool Post] + 3 tool holders<br />
* [https://www.amadeal.co.uk/acatalog/Fixed-Steady-for-Mini-Lathes-AMA_AC_CJ18A_FSRB.html#SID=145 Fixed Steady Rest]<br />
* [https://www.amadeal.co.uk/acatalog/Travelling-Rest-for-Mini-Lathes-AMA_AC_CJ18_TSRB.html#SID=144 Travelling Steady Rest]<br />
<br />
''You'll find all of the above on the shelf above the lathe, with the accessories in the wooden box, apart from the steadies, which live next to it. Change gears, spare parts, and most cutting tool tips/blanks are in labelled white rectangular tins behind the lathe.''<br />
=== Measuring Tools ===<br />
We have:<br />
* Various dial indicators - the one with the adjustable magnetic base stand is the most convenient for most lathe setup work.<br />
* 25mm micrometer (in little grey case)<br />
* Grey case containing set of measurement tools including dial calipers, micrometer, steel rule (metric & inch), engineers square, and a fish-tail gauge<br />
<br />
''We currently lack''<br />
* ''A tool height setting gauge''<br />
<br />
=== Hand Tools ===<br />
Some common tools needed for normal use are kept with the lathe, in or attached to the wooden accessories box:<br />
* 2 mm Allen key - adjusting cross-slide and compound gibs<br />
* 4 mm Allen key - quick change toolholder tool clamping screws + height adjust, tightening dials<br />
* 5 mm Allen key - four way toolpost tool clamping screws, engaging/disengaging threading indicator<br />
* 6 mm Allen key - locking/unlocking quick change toolholder<br />
* 8 mm spanner - locking carriage when 8 mm socket can't be used, locking gib adjuster nuts <br />
* 13 mm spanner - changing chucks, locking steady rest jaws<br />
* Very long needle nose pliers - for grabbing swarf safely, holding one end of emery cloth safely so you can keep your fingers away from the jaws, and extricating small objects from awkward places.<br />
<br />
== Change Gears ==<br />
[[File:BC puller 1.jpg|thumb|Custom puller for B-C stub shaft]] [[File:BC puller 2.jpg|thumb|Pulling the B-C stub shaft]]<br />
See "Conquest Super Lathe" manual ([[#Manuals|below]]), section '''4.7 Change Gears''', PDF pages 28-29, but see below for mesh adjustment. The LittleMachineShop.com "Mini Lathe User’s Guide" (also below) section '''Threading''' gives a far better explanation, with pictures and diagrams, but its for a lathe with a US 1/16 inch pitch leadscrew, not a metric 1.5 mm pitch one like ours, so you *MUST* ignore all the tables in that section, replacing them with metric mini-lathe (with 1.5 mm pitch leadscrew) equivalents. <br />
<br />
We have the following tooth count gears: 20,20, 30, 35, 40,40, 45, 50,50, 60,60, 80,80<br />
which consist of the OEM power feed gears + the metric change gear set. Apart from the metal 20 tooth pinions, they are all plastic, probably Delrin if the molded in 'POM' marking can be trusted, but possibly plain Nylon 6, and are metric Module 1.<br />
<br />
If we wanted to add the capability to cut US/Imperial threads we'd need to buy additional 55, 57 and 65 tooth gears, and possibly a 21 tooth metal pinion.<br />
<br />
CGTK's [https://www.cgtk.co.uk/metalwork/calculators/changegears/minilathe?gears1=20,20,30,35,40,40,45&gears2=50,50,60,60,80,80&gears3= Change Gear Calculator] ''(link preloaded with our gear list)'' is useful if you don't want to calculate the ratios from first principles. Not all suggested combos will physically fit.<br />
<br />
* Take care *NOT* to loose the keys in the A and D shaft keyways - turn each shaft till the keyway is up before removing the gear. <br />
* The B and C gears are coupled by a hollow stub shaft (with an integral key), which is so tight in the gears it has to be pressed or driven out - I've made a puller just for this task, kept in the change gears tin.<br />
* The center of the B-C stub shaft *MUST* be lubricated where it runs on its pin on the change gear banjo bracket, with grease or heavy oil. ''Seizure of the stub shaft due to running dry is a frequent cause of catastrophic mini-lathe geartrain failures!''<br />
* Don't get oil on the change gears as it can cause plastic gears to crack. Only PTFE drylube or plastic compatible white grease should be used on their teeth. <br />
* Adjust the B-C pin position in the straight slot first to set the C to D gear mesh, tighten its nut, then swing the whole banjo about the D shaft boss to set the A to B mesh, and finally tighten the banjo clamping nut.<br />
* Check both gear meshes have running clearance by turning the chuck by hand enough to complete one full turn of the leadscrew, and by attempting to turn the intermediate gear(s) to assess backlash, If excessive resistance is felt or if there's significant backlash, readjust the gears. If you have difficulty judging the mesh, a strip of 80 gsm copier paper (approx. 0.1 mm thick) wound into the meshing teeth before tightening the stud or banjo will give appropriate clearance once removed. Once setup, check the gears run quietly under power.<br />
* If the sum of the tooth counts C+D is the same as for the ones you just removed and they were correctly meshed, you don't need to move the stub shaft pin. If A+B is <u>also</u> the same, you don't need to move the banjo. e.g. If it was set up for 16:1 reduction power feed, 1 mm (40:60 - 50:50) for M6 and 1.5 mm (e.g. 40:60:40) for M10 pitches can thus be achieved by only swapping gears. <br />
<br />
''The change gears, puller, etc. and a box spanner for the banjo nut are kept in a white rectangular tin behind the lathe.''<br />
<br />
=== Power Feed ===<br />
When used for turning with power feed, the change gears should be set for a 16:1 reduction (A:20 : B:80 - C:20 : D:80) using the pair of small metal 20 tooth pinions and the 80 tooth plastic gears (largest in set), for a feed of 0.09375 mm per turn (1.5 mm/16). Unless continuing your threading project the next session, please re-fit the 16:1 power feed set after threading so the power feed is ready for use. <br />
<br />
* *ALWAYS* leave the feed direction selector lever in its neutral (no feed) position, and the half-nuts open after use.<br />
* *ALWAYS* check the carriage lock is disengaged before engaging power feed. Unlock the carriage after use. <br />
<br />
=== Threading Dial ===<br />
The threading dial is an aid to re-engaging the half-nuts at the right moment so the tool will retrace its previous path cutting deeper, rather than offsetting axially some fraction of the thread pitch and ruining your work. Its based on the concept of the lowest integer multiples of the leadscrew and thread ''(being cut)'' pitches that exactly match, but for mechanical simplicity it only covers certain selected multiples of the leadscrew pitch.<br />
<br />
We have a choice of three pinion gears:<br />
{| class=wikitable<br />
|+ Threading dial Pinion Gears<br />
|-<br />
! Teeth !! Colour Dot !! Usable lines !! OD gear !! Dist. per turn<br />
|-<br />
| 14 || Red || 1,7 || 7.51 mm || 21 mm<br />
|-<br />
| 15 || Orange || 1,5,9 || 8.05 mm || 22.5 mm<br />
|-<br />
| 16 || Green || 1,4,7,10 || 8.37 mm || 24 mm (2 mm/div)<br />
|}<br />
They are now colour coded, with a paint dot on the gear end face ''(the only non-wear surface)''. The 16 tooth one is normally left on the lathe, but disengaged when not threading to minimise wear on the lead screw. The others are kept in the Change Gear tin.<br />
<br />
There's a threading dial 'pickup' calculator here: https://www.cgtk.co.uk/metalwork/calculators/threaddialindicator <br />
<br />
Initially select ''Lathe:'' '''Custom''', and enter the following below:<br />
* ''Units:'' '''Metric'''<br />
* ''Lead Screw Pitch (mm):'' '''1.5'''<br />
* ''Thread Dial Indicator Gear Teeth:'' '''16,15,14''' <br />
* ''Lines on Thread Dial Indicator:'' '''12''' <br />
* ''Line Marking:'' '''Every Line Numbered'''<br />
Note the teeth list is entered in reverse order so the resulting table highlights any required pinion changes.<br />
<br />
N.B. The dial is only friction clamped to the pinion by its center screw. If you have any reason to suspect it may not be properly aligned: <br />
# With the power off and the carriage unlocked, engage the feed direction lever upwards. You'll probably need to turn the chuck by hand to get it to engage.<br />
# If the threading indicator isn't already engaged, loosen the threading dial support block bolt, pivot the block to engage the pinion with the leadscrew and retighten the bolt.<br />
# Engage the half nuts, again turning the chuck by hand till they drop in. <br />
# Turn the chuck a couple of turns, top towards you to take up any backlash, then lock the carriage, taking care not to push it left while locking it.<br />
# Loosen the screw securing the dial to the pinion.<br />
# Align the '1' line of the dial with the index line, by rotating the dial clockwise, then retighten the screw.<br />
# Don't forget to disengage half-nuts and unlock the carriage!<br />
<br />
The above instructions should result in the half-nuts engaging cleanly when exactly on any valid line when threading towards the headstock. If it is required to thread away from the headstock, there will be a slight offset from the line due to backlash between the spindle gear and leadscrew, so engage slightly early.<br />
<br />
Changing the pinion:<br />
# Loosen the threading dial support block bolt and disengage from the leadscrew.<br />
# Undo dial center screw, and remove it and the dial, dropping the old pinion out the bottom.<br />
# Oil the shaft of the new pinion with a drop of light oil and insert it from below, gear end down.<br />
# Refit dial and screw.<br />
# Check the dial and pinion turn freely with minimal resistance.<br />
# Align as above.<br />
<br />
== Tailstock and Steadies ==<br />
These are mostly used to support long work ''(long with respect to its diameter)'' to improve rigidity, increasing accuracy and reducing chatter. The Tailstock quill is also used with a drill chuck for drilling.<br />
=== Tailstock ===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock base]]<br />
The tailstock can be offset to turn shallow tapers between centers. We don't currently have the accessories to turn between centers, namely <s>a MT3 dead center for the spindle, or</s> any drive dogs for the work. Also realigning the tailstock after turning a taper can be a PITA. The photo shows the tailstock adjusting screw locations ''(C - Lateral, and D - Skew)'' and the block on the baseplate they engage with. Adjustments can only take effect when the tailstock locking lever is eased to take the pressure off the baseplate. As we don't have a MT3 center, one has to turn a fresh point on a test workpiece for a rough tailstock alignment reference. Fine alignment, to avoid inadvertent taper turning, can be done by mounting a long precision ground bar between the chuck (or preferably a center in the spindle), and a dead center in the tailstock and sweeping it with a dial indicator on the carriage. Finally a test cut should be taken at either end of a bar between centers, and the diameters checked with a micrometer. Assuming the bed has previously been properly levelled and shimmed to take out twist ''(not the case at RML as we don't have it bolted down)'', any remaining difference in diameter will be double the tailstock offset, smaller at the tailstock being offset towards the front. Fine adjustment cant be achieved by jacking with the screws, its best to ease the adjusting screws, bump the tailstock into alignment then take up the screws again, checking the alignment is maintained when the tailstock is unlocked and relocked. There is no vertical adjustment, though shims can be added between the tailstock and its base.<br />
<br />
==== Tailstock Quill ====<br />
There is a metric/imperial scale on the top of the quill, read against the end of the tailstock, for depth measurement when drilling. The tailstock quill has a 1.25 mm pitch thread and a 50 division dial. Each division is therefore 0.025 mm, and it only takes 4 full turns of the handwheel to move the quill 5 mm. <br />
<br />
To eject MT2 taper tooling and centers from the tailstock, wind the quill all the way in.<br />
<br />
N.B. The quill anti-rotation pin (dog-tip setscrew + locking nut in top of tailstock near to the quill lock) is only M5. It will sheer if a large diameter drill jams in the work. Please back it out clear of its keyway if using large drills, and use alternative methods of preventing chuck rotation. To re-engage it, crank the quill out till you can see the keyway, align it with the screw and screw in the screw till it gently bottoms out, then back it off a quarter turn. Try twisting the quill to check its properly engaged, then tighten the locking nut gently to hold the screw in position clear of the bottom of the keyway.<br />
<br />
=== Steady Rests ===<br />
We have two, both with brass tips that must be kept lubricated during use.<br />
<br />
The fixed steady mounts on the ways, and is most useful when turning longer work that wont fit through the spindle bore. Adjustment is critical, and the surface the tips run on must be smooth and concentric, as any misalignment that forces the work off center will result in the work wobbling in the chuck, marring it, with a high risk of it becoming un-chucked, which can be dangerous at speed.<br />
<br />
The travelling steady mounts to the headstock side of the carriage to locally resist the deflection of thin long work, due to the cutting forces. It only has two tips, to resist climb, and deflection away from the tool, and requires readjustment after every cutting pass.<br />
<br />
== Tooling and Tool Holders ==<br />
'''Key dimensional data:'''<br />
* The quick change holders accept up to 10 mm shank tools. <br />
* The four way toolpost has 50 mm long sides, a seat width of 15 mm and can clamp tools of up to 5/8" (15.875 mm) shank ''(check this)'', but the slot base is only 10.4 mm below the spindle center so cannot be used with >10 mm shank tooling unless it has a dropped tip. Large tooling with a centered tip is also problematic as you run out of height above the shank when trying to shim to match the spindle center height. <br />
<br />
===Quick Change Toolpost===<br />
I've got the quick change toolpost and toolholders setup for mostly easy use. The three toolholders came with cantilever height setting arms which historically haven't been installed as the supplied fixing screws were too short. That's all now sorted out and a HSS RH turning tool and a HSS hand-ground grooving/parting-off tool are now mounted in two of the holders and set to height. The third is kept free for other tools. <br />
<br />
The quick change toolpost has been modified with a spring to press the dovetail clamp outwards and help stop it twisting or flopping about to ease toolholder fitting and removal. The dovetail clamp (socket headed screw on toolpost side opposite dovetail) feels a bit stiffer than before, but will take less than half a turn to go from open (with the toolholder lifting out or dropping in easily) to fully clamped. As there is so much less clearance in the open position you should no longer need to wiggle the toolholder while clamping it to get a consistent height. If the dovetail clamp ever gets misaligned, twist it straight by eye, slacken off a bit further than usual to get a toolholder on, clamp it to align the dovetail then release, reseat the toolholder and re-clamp to ensure its at its preset height. You cant adjust the height by 'jacking' with the height screw due to its offset leverage. Instead, back off the height screw and hold the toolholder at the desired height while locking the dovetail clamp, then adjust the height screw (and locking nut) to hold it there, then check it doesnt change height significantly when you unclamp and reclamp the dovetail. <br />
<br />
Unfortunately the OEM height setting screws foul the toolpost locking nut handle. Currently, if you need to swap toolposts you will have to first remove the quick-change tool holder from the post. There is enough nut handle swing to allow the quick change toolpost to be unclamped and rotated to fine set the tool angle without removing the toolholder. It also seems the mating surfaces may be slightly out of square, as if you rotate the toolpost 90° or 180°, the nut swing may be insufficient to re-clamp it without removing the toolholder to do so. Add a M10 washer under the locking nut if the handle ends up pointing in an undesirable direction! A thin M10 washer is kept with the toolpost collar for this purpose, and will shift the handle position by about a third of a turn. <br />
<br />
''ToDo: Make a taller nut of a similar pattern, to clear the height setting screws.''<br />
<br />
===Four Way Toolpost===<br />
The OEM four way toolpost is significantly more rigid than the quick change toolpost + holders because it has fewer and thicker parts and less overhang. Therefore the four way toolpost should be used when using carbide tooling. It requires shimming under the tool to set the tip height to the spindle center height - see below. The tool shanks are mostly significantly less than 15 mm wide, so need to be centered under its clamping screws, tempting as it is push the shank in for full side contact with the toolpost. If possible clamp the shank with all three screws not just two.<br />
<br />
==== Shimming ====<br />
We typically only mount up to two tools, and want maximum rigidity, so use 50 mm x 15 mm shims, (the full seat area), preferably with deburred edges and radiused corners so they aren't a hazard to the operator.<br />
<br />
We have pre-cut and marked shims of the following thicknesses: <br />
* 1x 3.23 mm, 2.42 mm, 1.56 mm, 0.32 mm, and 0.25 mm<br />
* 2x 1.00 mm, 0.77 mm, 0.12 mm, 0.11 mm, 0.10 mm and 0.05 mm<br />
* 4x 0.53 mm<br />
<br />
Our shims are mostly found materials (hence the awkward thicknesses) and are mostly a mixture of aluminium and steel, with a couple of GRP ones. The toolpost seat '''<u>must be absolutely clean</u>''' to avoid embedding debris in the aluminium or GRP shims, to get a consistent height and avoid tilting the tool - wipe it every time you change a tool! Put the thin shims at the bottom of the stack to avoid the tool shank edges creasing them. Shims are kept in a little yellow plastic box with a clear lid, near the carbide tools case.<br />
<br />
I made a tool height setting gauge (T shaped black acrylic with steps in its sides) which can be used to check the tool tip height matches the spindle center height using either the flat of the ways or the saddle as a reference. The tool tip should just fit under the lip of the appropriate step, with the T arms across the ways flats or on the saddle. It is kept in the box with the carbide insert tools.<br />
<br />
''ToDo:'' <br />
<br />
* ''Cut more shims neatly, mark them with their thickness.''<br />
* <s>''Do test cuts and start noting shim stack-ups for various tools.''</s><br />
* ''Organise shim storage!''<br />
<br />
=== HSS Tools ===<br />
[[File:Tool Bit Geometry.jpeg|thumb|Single point cutting tool geometry]]<br />
Our HSS tools are made from 8 mm square bar stock, hand-ground to tip profile in-house. See LittleMachineShop's [https://littlemachineshop.com/images/gallery/instructions/grindingtoolbits.pdf Grinding Tool Bits] notes. <br />
<br />
I've installed our usual HSS LH turning and parting off tools in two of the quick change holders and set the heights correctly. There are a couple of other HSS tools or tool blanks knocking about. Taking heavy cuts turning steel (even with good cutting oil) blunts HSS tools fairly quickly, which are time-consuming to re-sharpen nicely without a dedicated tool & cutter grinder with appropriate jigs. Its worth noting that the usual 'speeds & feeds' tables are commonly based on surface speeds expected to give a half hour (active cutting) tool life before resharpening.<br />
<br />
I touched up the LH turning tool by lapping on wet & dry (silicon carbide) paper on glass (Aka: [https://en.wikipedia.org/wiki/Scary_sharp 'Scary Sharp']) working upwards through the grits 200, 400, 600 and finally 1000, initially 'bluing' the surfaces to be lapped with a marker pen to see which areas needed taking down more. The end of the tool was significantly uneven so I touched that up freehand on the bench grinder to flatten it when it became apparent that 200 grit lapping wasn't cutting where it needed to. There was an existing micro-bevel on the leading side, which I kept. Finally I 'dubbed' the leading corner vertical edge on the 1000 grit to give it a very slight nose radius. A test cut on brass gave a very nice finish when turning.<br />
<br />
''Ian B has purchased some spare 8mm HSS tool blanks - talk to a lathe trainer if your proposed lathe work needs custom ground HSS tooling.'''<br />
<br />
=== Brazed Tungsten Carbide Tools ===<br />
Somewhat of a half-way house between hand ground HSS tooling and insert tooling with the disadvantages of both and some more besides - e.g. they are much harder to sharpen. So why do we bother? Some tool geometries would be awkward and tedious to hand grind, and Chinese import brazed carbide tooling is about half the price of similar HSS tooling, and far more readily available. Also, for space constrained tooling like boring bars, if you want carbide, for insert tooling, the size of the insert and its clamping seriously limits the minimum hole diameter you can work in. I have purchased a set of 3/8" shank brazed carbide tipped boring bars, but we currently cant sharpen them, due to lack of a diamond grinding wheel. <br />
<br />
=== Tungsten Carbide Insert Tools===<br />
Decoding ISO insert tooling part numbers: https://www.cutwel.co.uk/blog/learn-the-turning-tool-iso-code-system<br />
[[File:Carbide set.jpg|800px|thumb|left|Our set of Tungsten carbide insert lathe tools (before the new inserts were fitted)]]<br />
<br />
{| class=wikitable<br />
|+ Tools, left to right, (+ last across top):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| SSKCR0610H06 || 75° through boring || SCMT06204 || Long || 6 || 6.34 || ''4.33''<br />
|-<br />
| SSSCR0610H06 || 45° deep facing, internal chamfering || SCMT06204 || Long || 6 || 6.13 || ''4.58''<br />
|-<br />
| SWUCR0610H05 || 93° boring, deep facing || WCMT050308 || Long || 6 || 6.22 || ''4.48''<br />
|-<br />
| SWGCR0810E05 || 90° RH turning & facing || WCMT050308 || Short || 8 || 8.25 || '''2.45'''<br />
|-<br />
| SSSCR0610E06 || 45° turning, chamfering || SCMT06204 || Short || 8 || 8.75 || ''1.93''<br />
|-<br />
| SSBCR0610E06 || 75° RH turning, chamfering || SCMT06204 || Short || 8 || 8.72 || ''1.98''<br />
|-<br />
| LW0810R-04 || 60° external threading || JCL15-120 || Short || 8 || 7.44 * || ''3.28''<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || 8.23 || ''2.5 ?''<br />
|-<br />
| LN0813R-04 || 60° internal threading || JCL15-120 || Long || 7.95 || 7.44 * || ''3.28''<br />
|}<br />
<br />
{| class=wikitable<br />
|+ More Tools, (loose in tin):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || ~8.5 (not in use) ||<br />
|-<br />
| [https://www.glanze.co.uk/product/glanze-12-mm-60-degree-metric-internal-threading-tool/ Glanse SIR0012K11] || 60° internal threading bar || 11IRA60 || Long || 12 dia || ??? || ???<br />
|}<br />
''Shim stack heights in bold are tested, in italic are only calculated.'' ''Tip heights marked * are with new JCL15-120I inserts. The single remaining plain JCL15-120 insert has a slightly higher tip height.''<br />
<br />
Carbide tooling typically requires two to three times more speed than HSS and at least a couple of 'thou' depth of cut for best results.<br />
<br />
Chatter can rapidly kill carbide tooling by chipping the cutting edge. To improve rigidity and reduce the risk of chatter, the cross-slide and compound gib screws need to be well adjusted so there is minimal play in the slides, tool stick-out should be minimised, the four way toolpost should be kept over the cross-slide, and the work should be kept close to the chuck (or otherwise supported by tailstock or steady rest) to avoid excessive deflection.<br />
<br />
Thermal shock is almost instant death to carbide, and when dry cutting the insert tip can run very hot, so do not add extra cutting fluid manually during the cut. Pre-apply what you need, evenly, before starting the cut.<br />
<br />
Parting off or facing to center is high risk - if the tool tip is even slightly below center or if tool or work deflection takes it below center, the work will tend to climb over the tool tip as the cut approaches center, breaking the insert. To avoid this, the tool should be shimmed slightly above center, sufficient to allow for work and tool deflection, and unless very close to the chuck, a steady should be used. Its often preferable to part to a couple of mm dia. remaining then stop and saw through the remainder. Parting off hollow parts is much lower risk.<br />
<br />
Further investigation of the Tungsten carbide insert tool height situation is not encouraging - the so-called 'set' in question does not have a consistent tip height ''(see above table)''! In a real set, the insert seats *should* be machined allowing for the insert thickness to bring all the cutting edges to the same height with respect to the shank underside. However if you place them tip to tip on a table its easy to see there is considerable height variation, so they need to be individually shimmed (or at best, one machined shim will only be right for two or three tools). At this time we don't have dedicated shim stacks for each tool.<br />
<br />
A 2.42 mm thick shim brings the SWGCR0810E05 90° RH turning & facing tool almost exactly to center height, and good results were obtained turning 1" steel pipe. However facing 50mm steel bar stock to center found it to be slightly low, leaving a fractionally under 0.05 mm 'pip' so it needs another 0.03 mm to bring it fractionally above center. Fractionally too high is generally preferable to fractionally too low, due to tool deflection, so adding an 0.05 mm shim to the stack should produce optimum results.<br />
<br />
==== Inserts ====<br />
Ian B has purchased the spare inserts we needed in sets of five. He even was able to get the CK3 parting-off inserts which had been difficult to source!<br />
<br />
Inserts used in above tool set:<br />
* 3x SCMT06204 (square, indexable) https://www.rdgtools.co.uk/acatalog/SCMT-06-Carbide-Insert.html<br />
* 2x WCMT050308 (triangular, indexable) https://www.rdgtools.co.uk/acatalog/WCMT-05-T3-08-5XTIP-8813.html<br />
* 2x JCL15-120 (60 deg threading point) https://www.rdgtools.co.uk/acatalog/X5-JCL-15-120L-THREADING-TIPS-60-DEGREE--X5-TIP---23455.html<br />
* CK3 (parting off) https://www.rdgtools.co.uk/acatalog/CK3-CARBIDE-TIPS---PARTING--BOX-OF-5PCS--9437.html<br />
<br />
Inserts used in other tools:<br />
* 1x CK3 (as above) also missing from spare parting off tool<br />
* 1x 11IRA60 in Glanse threading bar + 1x spare<br />
<br />
=== Drills ===<br />
Various sizes of center drills are kept in a plastic bag next to the wooden accessories tray. There's also a small box of 2.5 mm center drills.<br />
<br />
We have a set of 11 TiN coated HSS drill bits from 1.5 to 8 mm, (in a cylindrical plastic index box) for tailstock drilling of brass, aluminium and non-abrasive plastics. To keep them sharp enough for the precision work we expect from the lathe, please don't use them for steel or reinforced plastics, and don't borrow them for non-lathe use. Metric and US [https://littlemachineshop.com/reference/numberdrillsize.php numbered]/[https://littlemachineshop.com/reference/letterdrillsize.php lettered] general use HSS drill bits are kept in two red metal index boxes next to the drill press.<br />
<br />
== Using the Lathe ==<br />
=== General ===<br />
Making dimensioned parts is primarily done by touching off the tool tip on a reference surface (with the lathe stopped, turning the chuck by hand), zeroing the handwheel dial, then manually counting turns and divisions. When backing off the tool its best to do so by exactly one whole turn so you don't forget the previous dial position. Stopping and measuring the work before taking the final cuts is essential if high accuracy is required. ''I've changed out the dial setscrews for flat tip ones with a tiny slug of solder under them so the dials are now friction fit on their shafts. i.e. if you hold the handle firmly taking up the backlash in the direction of cut, you can zero the dial just by grabbing and twisting it.''<br />
<br />
Carriage movement is less easy to measure as the handwheel is uncalibrated and advances an awkward bit over 19.2 mm per turn. Your options here when shoulders or other features must be exactly positioned are, in order of increasing accuracy: <br />
* Use measuring instruments, scribe the work at the desired length then work to the scribed line. Its often convenient to black the work with a permanent marker, then scribe with the tool tip, turning the chuck by hand.<br />
* for short distances, lock the carriage and use the compound, set parallel to the work<br />
* Set up a long travel dial indicator to measure carriage motion. <br />
N.B. with the leadscrew stopped, and the threading dial engaged, with its default 16 tooth gear, it will make one turn for every 24 mm of carriage movement (2 mm/div). This isn't accurate enough for positioning but is sufficient to check you aren't out by a whole mm or more.<br />
<br />
Do not allow any solvents to contact the chuck guard clear plastic as it will make the plastic brittle, or even craze it, and try to avoid melting it with the work light!<br />
<br />
===Speeds & Feeds===<br />
A cutting speed chart for HSS tooling, published by Model Engineer magazine can be found [https://www.model-engineer.co.uk/sites/7/documents/cutting%20speed%20chart.pdf [here<nowiki>]</nowiki>]. The second row is the target feed rate and the rest of the chart, apart from the diameter column is RPM.<br />
<br />
For carbide tooling cutting iron and steels, recommended speeds are generally three times higher than for HSS, but the CJ18A 2500 RPM max. spindle speed (in high gear) means you can only reach the optimum speed range for over 15 mm dia work. For small diameter work, HSS tooling may well be a better choice.<br />
<br />
An online metric speeds calculator is here: https://www.cgtk.co.uk/metalwork/calculators/cuttingspeeds <br />
<br />
How to do the maths to calculate speeds and feeds: https://www.cutwel.co.uk/blog/speeds-feeds-made-easy<br />
<br />
If you can hear the lathe 'sing' as it cuts, you are getting chatter, which invariably results in poor surface finish. Try decreasing (or possibly increasing) the spindle speed till the resonance stops. <br />
<br />
Once you have a wavy surface due to chatter, a light cut wont clean it up as the tool 'twangs' from peak to peak. You have to take a deep enough cut to get under it. For precision parts, its therefore desirable to take a trial finish cut while still 0.5 mm or so oversize, to give an opportunity to tweak the cut to get a good finish, check for taper, and that the part wont be undersize (on your test finish cut nominal diameter).<br />
<br />
=== Slide Locks ===<br />
* The carriage can be locked to the ways using the M5 hex screw through the top of the saddle to the left of the cross-slide. Double check the leadscrew is disengaged and the half-nuts open before locking it. Lock it when facing.<br />
* The cross slide can be locked by a M4 socket headed cap screw just in front of its middle gib screw. Locking the cross slide is helpful when turning very shallow conical features where the cross slide handle is in the way of the compound.<br />
* The compound slide can be locked by a M4 socket headed cap screw in line with the edge of the toolpost mount on the side with the gib adjustment screws. In normal use it should be kept backed off half a turn but it is desirable to tighten it for parting off operations to keep the resulting end faces flat.<br />
<br />
=== Compound ===<br />
The compound consists of a locking swivel and a top slide allowing cuts to be made at an angle to the axis e.g to produce bevelled or tapered features. There is a difference between US and UK usage, in the US a compound angle of 0° means the compound slide is parallel to the cross slide, but in the UK, 0° is parallel to the ways. The compound angle indicator on the CJ18A follows UK practice, 0° parallel to the ways, but it is not to be trusted, its out by a few degrees!<br />
<br />
One of the deficiencies of the CJ18A lathe is the difficulty of setting the compound angle. It is held and locked by two screws hidden under the top half of the compound slide, which must be wound back till its toolpost end is clear of the pivot point to access them. This may have to be repeated several times to snug them up enough to tap it to the desired angle, then finally tighten them. <br />
<br />
We generally keep the compound slide set approximately parallel to the ways so it can be used for short-distance longitudinal positioning without measuring. However it is unlikely to be closely parallel unless a test bar has been swept with a dial indicator on the slide, or test cuts made on a large OD workpiece and checked for taper.<br />
<br />
=== Chucks and Chuck Jaws ===<br />
==== Terminology ====<br />
* Inside jaws have steps on the outside to grip the ID of hollow work, but can also be used as outside jaws on small diameter parts (i.e. that fit through the spindle). <br />
* Outside jaws have steps on the inside to grip the OD of the work.<br />
* Universal chucks have a scroll plate with a spiral screw thread that moves all the jaws.<br />
* Independent chucks have individual adjusting screws for each jaw.<br />
<br />
==== The Chucks ====<br />
* The three jaw universal chuck can only grip near round or hexagonal work, which it centers, but its concentricity is not perfect so e.g. if you reverse the work and continue turning at the same diameter from the other end, you will see a line where the turned surfaces meet. It has separate sets of inside and outside jaws, and we normally keep the inside set installed to use as outside jaws for small diameter work.<br />
<br />
** Our jaws are individually numbered, stamped in the groove. They must be fitted in the correct sequence. The jaw slots are not clearly marked. Lowest runout for small dia. parts is achieved if you fit the jaws with #1 anticlockwise of the makers mark, then continue anticlockwise for #2 and #3.<br />
** A large strong rubber band is a great help getting all the jaws started on the scroll together - with slots #1 and #3 above the centerline and the scroll thread outer tip between #1 and #3, insert jaws #1 and #2 and put the rubber band round them to keep them in their slots. Insert jaw #3 and stretch the rubber band over it to hold it up into its slot. If the scroll was positioned correctly, all jaws should be at the same initial radius. The jaws can now be cranked in with the chuck key and they should all engage in step so they meet in the middle.<br />
:: ''Mini-lathe.com have the best instructions for [https://www.mini-lathe.com/mini_lathe/chucks/chucks.htm#Installing_Chuck_Jaws changing the jaws].'' <br />
<br />
* The four independent jaw chuck can grip most roundish or squarish work, which can either be carefully centered by the user, or deliberately gripped off-center. <br />
** Its jaws are reversible so can be swapped from inside to outside by simply cranking each jaw out and reinserting it the other way round, one at a time. DON'T move the jaws to different slots as they are likely to bind.<br />
** When setting up to face the sides of rectangular objects held crossways, it may be helpful to use both inside and outside jaw orientations, in symmetrical opposing pairs.<br />
** Its screws move their jaw 1/8" (3.125 mm) per turn<br />
<br />
* The jaws must '''never''' protrude from the chuck OD by more than one step, and for safety, its preferable they don't protrude at all, as they make the gap between the front of the bed and the chuck body an even more unforgiving meat grinder, and as the number of teeth engaged with the scroll or screw decreases, they loose strength, just when you need it the most to grip larger/heavier work. <br />
<br />
''Neither chuck is well suited to gripping tapered work safely. When seating work that doesn't quite fit through the chuck bore (which is larger than the 20mm spindle bore limit), be careful that it isn't seating on the chamfered edge of the chuck bore as it is far to easy to get the work slightly cocked so it doesn't run true.''<br />
<br />
==== Changing Chucks ====<br />
* When changing chucks, use the small grey plastic mat to protect the ways under the jaws in case you drop the chuck.<br />
* The spindle nose has two patterns of holes - the three hole pattern is for the three jaw chuck and the faceplate, and the four hole pattern is for the four jaw chuck. One hole is shared between the patterns, and is marked on the spindle nose.<br />
* To fit a chuck:<br />
** First check that the spindle nose and chuck back and recess are free of swarf, grit or other debris. Any foreign objects will tilt the chuck causing excessive runout and may mar the surfaces.<br />
** Remove the nuts and split lock washers from its studs, line its studs up with the hole pattern (preferably with the stud nearest anticlockwise to the makers mark through the marked spindle hole), fit and hold it in place with your right hand, and with your left, get the lock washer and nut on the top stud, and take up the slack.<br />
** One one nut is on, you no longer have to worry about dropping it, and can work round fitting the remaining washers and nuts, taking up the slack on each as you fit it. <br />
** Next, work round again getting them all finger tight, then tighten them gently, and finally work round fully tightening them. <br />
* Removal is the reverse of refitting. Put the washers and nuts back on the chuck's studs so they don't get lost.<br />
<br />
==== Gripping Threaded Work ====<br />
It is generally undesirable to chuck work gripped on a screw thread, as it is difficult to hold the work securely and get good concentricity while avoiding crushing the thread crests. However, if one must, one of the better ways of doing so is to wind a wire helix to fit the thread then clamp on the outside of the wire so it seats on the flanks of the thread. The wire should be mild steel or soft iron for steel parts and copper for aluminium and brass parts, single strand, round and of uniform diameter a little less than the thread pitch. It can be wound on the lathe, in reverse, by chucking a sacrificial mandrel of the same diameter and thread pitch, hooking the end of the wire round or under the jaw, against the direction of rotation, then holding the other end of the wire under tension with pliers and starting the lathe dead slow. Once wound and removed from the mandrel, the ends must be trimmed then it should be screwed on to the threaded work to provide a surface to chuck on.<br />
<br />
=== Faceplate Work ===<br />
Faceplate work is probably the most dangerous operation you can (or rather should) perform on a lathe. The working area is a large diameter spinning surface with protruding clamps to fixture the part that it is impractical to guard. Protruding clamps, studs, nuts etc. are very difficult to see at speed.<br />
<br />
'''Treat the faceplate with great respect and caution if you wish to continue to be able to count to ten on your fingers!''' <br />
<br />
The 65 mm cross-slide travel vs the 80 mm faceplate radius is a serious limitation that may require creative compound, toolpost and tool setups for larger parts, and doing full face cuts in two sections.<br />
<br />
''It is common practice to skim the faceplate to ensure it runs true. We have not (yet) done this, and wont till the spindle is in better bearings and the nose reground to minimise runout.''<br />
<br />
==== Clamping ====<br />
Open ended/sided clamps should be oriented so that cutting forces drive the work towards the clamping bolt/stud, not out from under the clamp. Minimize the protruding length of thread past the clamping nut, if necessary using sacrificial bolts or studs you can cut to length, or even using a long M8 stud for one of the faceplate mountings, so you can get a clamp nearer to the faceplate center. Double-check all clamps are secure, manually turn the faceplate to check the work and clamps clear the ways, top-slide and toolpost, and stand out of the 'line of fire' (a disc extending from the faceplate) when spinning up the work for the first time. <br />
<br />
If you need to machine close to a clamp, consider marking a safe limit circle on the faceplate and work with a marker pen to make it easier to see how close the cutting tool is to crash disaster. <br />
<br />
I strongly advise reading chapter two of Tubal Cain's book "Workholding in the Lathe" several times before your first faceplate setup, and if possible get another experienced lathe user to check your first few setups before spinning them up.<br />
<br />
==== Chuck Guard Removal ====<br />
The faceplate is too large diameter to fit under the chuck guard, but the guard has an interlock switch wqhich must be closed for the lathe to run. The guard is now fitted with wing nuts so it can be removed allowing the the interlock switch to close when using the faceplate. It *SHOULD* *ALWAYS* be refitted if a chuck is fitted, except when turning work too large to clear the guard. <br />
<br />
''The chuck guard is primarily there to make it very difficult to start the lathe without removing the chuck key and to reduce the area of large diameter spinning surface exposed. It may slow down the projectile if a chuck sheds a jaw but is unlikely to stop it. Also it serves to contain coolant spray spun off the chuck. As we don't use flood coolant this usually isn't an issue for us. As setting up for faceplate work doesn't use a chuck key, and the most hazardous zone is the face of the faceplate, with its spinning projecting clamps, with full access required for machining operations, which a guard would not cover, the consensus is that removing the guard is an acceptable risk.''<br />
<br />
=== Turning and Facing ===<br />
We are getting good results in aluminium, brass, and even steel using HSS cutting tools in quick-change tool holders, and the ~ 94 um/turn power feed. Unfortunately due to lack of rigidity in both the machine and smaller diameter parts, if you don't want the outer end to be over diameter, a light final cut and multiple 'spring' passes will probably be required.<br />
<br />
For aluminium, a sharp HSS tool and 0.5 mm (20 div) depth of cut gives good results with power feed for rapid stock removal. Its also easy maths as each cut takes ~ 1 mm off the diameter. Finish cuts should be much finer, 0.1 mm (4 div) is 'in the ballpark'.<br />
<br />
For steel, using carbide insert tooling, a 0.25 mm (10 div) depth of cut is more appropriate, and with pre-applied cutting oil, gives reasonable results with power feed if you use enough speed. The maths is not quite so easy as you are only taking 0.5 mm off the diameter per pass. Again, use finer finish cuts but try to plan your cuts so the final cut is still cutting, not smearing the surface!<br />
<br />
When facing or parting off, some skill is required to turn the cross-slide handwheel steadily to get a decent finish and to avoid shock-loading the tool tip. Increasing the spindle speed in one or more steps to keep up with the reducing diameter is advisable, but avoid speeds that cause resonances (resulting in chatter). When parting off, small through-hole parts may be caught on a thin rod chucked in the tailstock, and pre-positioned inside the work with its tip right up to the parting off position.<br />
<br />
==== Using the Steady Rests ====<br />
For the fixed steady rest, see Blondihacks' Lathe Skills #26 - How To Use a Steady Rest! [[#Youtube_Playlists_&_Videos|{below}]]<br />
<br />
Ours doesn't have ball bearing fingers, so a smooth surface on the work and adequate lubrication are essential. The thumbscrews can only tighten the fingers, so for small adjustments outwards you need to either slack off the clamping nuts or ease them slightly and use a drift against the back of the finger's slot. Once set, check the chuck still turns freely.<br />
<br />
The traveling steady rest needs to run on a machined surface, so at least for the first pass, must follow the tool, so its difficult to avoid using more compound slide overhang than is desirable. An initial surface should be cut next to the chuck or tailstock center before fitting the steady rest.<br />
<br />
Both are a PITA to fit - the fixed one has to have its clamping post inserted up through the bed, and the supplied spanner is useless near the headstock, and the travelling one's mounting holes on the saddle almost invariably need swarf picked out of them.<br />
<br />
==== Turning Between Centers ====<br />
<s>Using a MT3 to MT2 reducing sleeve, the MT2 dead center can be fitted in the spindle.</s> ''Currently the MT3 spindle taper is compromised.'' Alternatively, a soft center can be turned immediately before use in the three jaw chuck, but that must have its 60° point re-cut to concentric if the chuck is disturbed, and needs to be either large enough to bear on the chuck body, or must have a lip to bear on the end face of the jaws to take the axial thrust. Recutting the center is a PITA, as the compound angle must be set to 30° anticlockwise, then reset to a true 0° afterwards. Maybe a right-hand 30° end angle zero rake form tool is the answer, or use the carbide insert tool SSKCR0610H06 as a form tool with the toolpost rotated 15° anticlockwise.<br />
<br />
With the MT2 live center in the tailstock quill, this gives us a center either end of the work to hold it.<br />
<br />
We also need a drive dog similar to [https://littlemachineshop.com/products/product_view.php?ProductID=4473&category=1 this], and the corresponding drive post to bolt to the spindle nose. I have some 25mm bore thick wall iron pipe, which should do nicely. Lengths of the dog's straight tail and of the post TBD after I check how much the center protrudes. N.B. its recommended to tie the tail to the post to keep them in contact so they don't slam. ''Currently we will need to drive from the chuck jaws. Possibly use the exterior jaws with a short soft center gripped on the inside end and drive from the highest step.''<br />
<br />
=== Drilling ===<br />
Always start with a center drill so deflection of longer bits doesn't start the hole off-center. For larger bits (> 5 mm), first drill to the web size, then to final diameter. For a precision hole, drill slightly undersize and ream to final diameter. ''Supply your own reamers!''<br />
<br />
Caution: See note about the quill anti-rotation pin in section [[#Tailstock Quill|Tailstock Quill]] above.<br />
<br />
=== Boring ===<br />
Caution: As the spindle doesn't extend right through the headstock housing, if boring in a through hole, chips tend to fall out the back and tumble in the spindle bore till they fall into the change gears. To avoid this, one should plug the spindle bore with a wad of paper towel or rag and when cleaning up afterwards, use a rod to push it through towards the tailstock, with the chuck jaws (if fitted) wound clear of the spindle bore.<br />
<br />
A swivel bladed hole deburring tool (pale blue handle) can be found in the main room on the windowsill behind the drill press.<br />
<br />
A couple of boring jobs have been bodged with an awkwardly angled turning tool and achieving acceptable effective rake with enough clearance to reach deep enough into the hole has been problematic. I reviewed the tools we had and found none suitable for starting out in a 13mm bore, the max diameter we can (easily) drill. I therefore decided to buy a set of boring bars and make a holder for them. I had difficulty finding anything affordable under 10mm shank - the best low cost option was a [https://www.amazon.co.uk/dp/B07P5LGVBX set of nine 3/8" (9.525 mm) shank brazed carbide tipped boring bars], which would be close to the max capacity of the quick change boring bar holder - if we had one! Unfortunately this holder for our specific toolpost is difficult to find except in a toolpost bundle. Another annoyance is the variable tip height of the set, varying from 1.8 mm to 2.8 mm above the center of the shank.<br />
<br />
I therefore decided to make a boring bar holder of the [https://littlemachineshop.com/products/product_view.php?ProductID=1700 Littlemachineshop.com (USA) style] for use in the four way toolpost, as the additional rigidity will certainly help. Starting with a slightly over 50 mm length of 16 mm aluminium square bar and using the four jaw chuck , both ends were faced and an attempt was made to find its center and center drill it. It was then drilled out to ~9.8 mm after much drama due to blunt drills and drills that cut ~1mm oversize. Too big, but beggars cant be choosers as we didn't have a boring bar holder or a 3/8" reamer. Unfortunately the final hole ended up significantly off center. It was then chucked crossways and ~1 mm skimmed off its thickest side to gain clearance to allow it to be shimmed to height, then one side was slit lengthwise manually with a hacksaw.<br />
<br />
It was fitted to the for way toolpost and loaded with a booring bar, which clamped firmly. A 0.86 mm shim stack brought the tip of the largest boring bar almost spot on center height, with the difference easily accommodated by twisting the tool slightly. The three jaw chuck was then remounted, and a piece of iron pipe chucked for a test. It cuts well and leaves a decent surface finish.<br />
<br />
''The boring bar setup is a work in progress - talk to me before attempting to use them if you have a project that would benefit from boring..''<br />
<br />
ToDo: get something that can sharpen tools tipped with this grade of carbide - it needs some sort of diamond (or possibly CBN) wheel as green grit silicon carbide does little more than polish it. ''N.B. diamond wheels are rapidly eroded by grinding steel, so the supporting steel seat must be undercut with a regular grinding wheel before the diamond wheel can contact it.'' <br />
<br />
We'll also need 50 mm square sheet shims to fit under the toolpost to gain clearance in the toolpost above the tool or toolholder. A 2.4 mm shim would give us about the same above and below spindle center height, and we probably need a small selection of thinner ones.<br />
<br />
=== Thread Cutting ===<br />
The objective is to cut a thread that complies with the ISO metric thread profile. Our lathe is not currently equipped to cut non-metric threads, (with the exception of BA which have pitches based on metric threads of that era).<br />
<br />
[[File:ISO and UTS Thread Dimensions.svg|frame|center|Metric Thread Profile - from the geometry, H is ~86.6% of P]]<br />
<br />
Metric thread data - See 'Preferred Sizes' at: https://en.wikipedia.org/wiki/ISO_metric_screw_thread<br />
<br />
See "Mini Lathe User’s Guide" section '''Threading''' for general techniques *ONLY*, and above for change gears and threading dial setup.<br />
<br />
Amadeal specify the max. thread pitch as 2.5 mm. Any thread pitch greater than 1.5 nn requires the change gears to gear up. When gearing up it is desirable to distribute the ratio as evenly as possible over the two pairs of gears in the geartrain to avoid excessive tooth loading.<br />
<br />
==== External Threading ====<br />
Initially turn work to required Major Diameter, set up change gears and threading tool, touch off on the work, zero the top and cross slide dials, and do a 'scratch' pass to check the pitch. Back off the tool, return the carriage, and re-engage the half nuts on a valid dial line clear of the end of the thread then immediately stop the lathe, and hand turn the chuck till the tool tip is (hopefully) over the scratch to check the thread pickup. If all is good, return the carriage again, restart the lathe and start cutting your thread. <br />
<br />
Methods of doing so vary depending on the size of the thread and toughness of the metal, but straight-in plunge cutting is generally to be avoided as has the highest cutting forces, and does not reliably keep the carriage (and top-slide if set parallel to the work) loaded to avoid pitch errors due to backlash. <br />
<br />
If leaving the half-nuts engaged and reversing the lathe to return to the start of the thread for the next pass, its absolutely essential to back the tool out of the thread for the return pass as it will not follow the path of the cutting pass due to backlash in the geartrain, leadscrew mounts and half-nuts.<br />
<br />
==== Internal Threading ====<br />
''<nothing here yet>''<br />
<br />
== Cutting fluids ==<br />
=== Why bother? ===<br />
[https://youtu.be/mRuSYQ5Npek Watch this video] and contemplate what's actually happening to that thin ribbon of metal being removed. Most of the lathe's motor power is being turned into heat by internal friction in the chip being removed in the zone around the cutting edge, and surface friction at, and immediately behind the cutting edge, near-instantly heating the chip by up to several hundred degrees. Reducing the surface friction using a suitable cutting oil reduces the strain on the machine as a whole, and reduces workpiece and tool heating (and thus expansion) with consequent improvements in maximum usable feed and depth of cut, surface finish and accuracy. It also drastically increases the life of the cutting edge.<br />
<br />
=== Practicalities === <br />
We don't have a coolant system for the lathe and *really* don't want the maintenance hassles of using soluble cutting oil/coolant as if used infrequently its a PITA to keep recirculated high water content cutting fluids from going rancid and stinky, and they can also rust the ways, so even a total loss gravity feed system is problematic. Therefore if dry machining doesn't give a good enough finish, we tend to use oil applied topically, by hand to the work. <br />
<br />
* Hard brass is typically free-turning without oil, however some light oil for the final cut can improve surface finish, but with the disadvantage that it will increase loose chip buildup on the tool as hard brass typically forms short spalls or splinters rather than curly chips.<br />
<br />
* Many Aluminium alloys tend to be gummy, and Paraffin or other mineral spirits mixed with a little oil can help prevent the aluminum welding to the tool edge. WD40 will do at a pinch, but its messy to apply from a spray can.<br />
<br />
* Steel really needs *GOOD* cutting oil. Lard oil is the traditional choice for steel. If there are any objections to lard oil, we should bite the bullet and get some commercial dark high Sulphur cutting oil, but beware, many such oils use an additive package that includes lard oil.<br />
* Cast iron (except ductile) should be cut dry, as the carbon micro-inclusions self-lubricate it, and the carbide in the dust (primarily Cementite) are very abrasive, so tend to form a grinding compound if mixed with oil. <br />
<br />
I've sorted out an oil pot lid with a 1/2" brass collar soldered in to give a nice smooth sided hole, for ease of use and to minimize the risk of spills when using a brush to apply cutting oils, and got some dirt-cheap brushes. It fits Shippam's paste (and similar own-brand spread) jars and I've found several jars and ordinary lids to seal them for storage. Unfortunately it isn't the easiest to get this type of jars' lids back on square so they seal properly, and if you over-tighten them and there's a temperature change, they can be a total <expletive> to reopen. Using the rubberised handles of a large pair of pliers to grip the jar lid just above its rim is the best option, and avoids damaging the lids.<br />
<br />
''N.B. For the smaller brushes, the glue holding the bristles in is attacked by paraffin. To prevent loss of bristles, crimp the aluminium ferrule of each new brush of this type before use.''<br />
<br />
We have, in labelled jars:<br />
<br />
* Sulphurised Lard oil thinned with paraffin. Best choice for heavy cuts and threading in steel but stinky.<br />
* Lard oil thinned with paraffin. Good for steel and acceptable for softer copper alloys<br />
* Paraffin with a trace of light oil. Good for aluminium, and can help prevent squealing chatter on finish cuts in brass.<br />
<br />
I've also got some paraffin wax (in the form of a stubby candle), which can be applied lightly (under power) to brass and aluminium stock especially on the finish pass. It makes less mess than oil but unfortunately tends to build up on the tool tip, making it difficult to 'work by eye' without frequent pauses to clean the tool tip.<br />
<br />
We've also got a tin of [https://www.rocol.com/products/rtd-compound Rocol RTD cutting compound], which is a thick paste. Its highly recommended for drilling and tapping steel (in the drill press or by hand), but as a paste, is less useful for general lathe work unless thinned to a fluid consistency, e.g. with paraffin or white spirits. OTOH its certainly worth trying for high speed facing steel as it is less likely to get flung off.<br />
<br />
== Cleaning and Maintenance ==<br />
Swarf is a significant cut hazard to the operator, especially stringy swarf from cutting steel. Never touch it bare-handed - always use a tool e.g. a brush, or a hook, or needle nose pliers for grabbing long swarf.<br />
<br />
* After use, brush all swarf off the toolholder, compound and cross slide etc. ways and leadscrew. Ian B has blocked off the opening at the headstock end of the rear splashguard (to try to keep swarf out of the motor), so one must sweep the swarf towards the open tailstock end and catch it in a dustpan or similar. Preferably, also thoroughly clean out the chip tray under the lathe, but at least sweep out visible swarf.<br />
* Wipe up any cutting fluid residue and re-lubricate affected sliding surfaces with way oil.<br />
* Do not solvent clean the chuck guard, as it will make the plastic brittle, or even craze it. Water with a little detergent is permissible for cleaning it, with the guard totally removed from the lathe.<br />
<br />
Before engaging the half-nuts for power feed/threading, check the leadscrew is clean! ''Best cleaned under power, with a toothbrush.'' <br />
<br />
'''Caution:''' The traverse gears behind the carriage handwheel are in an open-backed housing and tend to become packed with swarf! Swarf buildup here will result in jerky carriage movement. Clean out as much as you can with a toothbrush ...<br />
<br />
===Lack of lubrication and/or swarf or dirt build-up can be disastrous===<br />
* If using the change gears/power feed, lack of lubrication of the B-C stub shaft center pin or either leadscrew end bearing can result in seizure and immediate destruction of one or more gears in the gear train or worse. <br />
* Small pieces of swarf can get between the saddle and ways, or into the slides degrading accuracy, possibly permanently if hard swarf scores them, or jamming them. The carriage handwheel gears behind the apron are notorious for accumulating swarf, and swarf buildup on the leadscrew can prevent the half-nuts engaging properly, resulting in scrapped work, and possibly stripped half-nuts. <br />
* Metal swarf can get into the motor (''though Ian B has modified the rear chip catcher to reduce the risk)'' or into the control box via the leadscrew, and short-circuit stuff. At best it will blow the fuse and need a strip-down to clean it out, at worst it may require a replacement [https://www.amadeal.co.uk/acatalog/Speed-Control-Circuit-Board--12amp-AMA_SP_CJ18_SCB12.html#SID=12 speed controller] ''(currently £96)'' and/or [https://www.amadeal.co.uk/acatalog/550W-motor-for-CJ18A-Mini-Lathe-467.html#SID=240 motor] ''(currently £105)'' and possibly other electrical parts. We should probably fit a [https://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C3-Mini-Lathe-Spares/C3-256-Leadscrew-Grommet-Dustproof-Cover C3-256 Leadscrew Grommet] to keep swarf out of the control box, as it tends to drop onto the 'Filter' board which is mounted horizontally, below the leadscrew.<br />
* Grit from grinding, sanding etc. forms a grinding paste with the way oil, and will rapidly wear out the ways, saddle and slides. Keep grit off at all costs e.g. by covering the ways and slides during grinding/sanding operations, and if there's any chance grit has gotten where it shouldn't, clean and re-lubricate *BEFORE* moving the carriage or slides, then move the carriage and slides, wipe down where they were with a clean paper towel and check there's no remaining traces of dirt other than clean way oil on the paper towel. If it doesn't come clean when you re-lubricate and move it again, a full strip down may be required to solvent clean and relubricate the precision sliding surfaces.<br />
* Although a metalworking lathe *can* be used to turn hardwood, wood dust and small chips are extremely pernicious, as they get everywhere, even clinging to clean surfaces, are abrasive due to their silica content, and are hygroscopic, promoting rust. An even more thorough clean-up than after using abrasives is needed, immediately afterwards. Oily wood dust and fine wood chips in significant quantities are a fire hazard, even in the trash bin.<br />
<br />
===Lubrication===<br />
See section: "Lubrication" in LittleMachineShop.com "Mini Lathe User’s Guide" [[Ian_M's_Lathe_Notes#Manuals|(below)]]. As we usually only open two nights a week, in the table on page 16, Daily lubrication becomes Weekly and Weekly becomes Monthly.<br />
<br />
===General Maintenance===<br />
* The grubscrews holding the cross-slide and compound slide dials tend to loosen due to vibration and use of the dials. Keep them snugged up, but not so tight the dials cant be set without an Allen key.<br />
<br />
* The screws holding the cross-slide nut tend to work loose due to vibration. Crank the handle to and fro through the backlash and visually check there is no movement of the screw heads in their holes. If there is, see the [[#Excessive_cross-slide_backlash|notes below]].<br />
<br />
===Removing the Carriage===<br />
Its possible to remove the carriage from the bed for cleaning etc. without dismantling it. The only stop to its motion is the righthand leadscrew bearing.<br />
<br />
Start by removing the tailstock. Crank the carriage to the tailstock end then remove the leadscrew bearing (two screws and a nyloc nut on the leadscrew end). With the half-nuts open, hold the leadscrew centered in them and crank the carriage off the end of its rack, then slide it off the end of the bed.<br />
<br />
Refitting is the reverse of removal, except (if its gibs are correctly adjusted) the carriage will be very tight on the end of the bed ways so may be difficult to work onto the ways without a stack of blocks of wood or similar to support it at exactly the right height. The righthand leadscrew bearing must be refitted with the carriage as close as possible to it and the half-nuts firmly closed to support the leadscrew at the correct height to hold it in alignment while the screws are being tightened. The nyloc nut controls leadscrew end-play. Fully tighten it then back it off slightly till the leadscrew turns freely with its change gear removed.<br />
<br />
If the Apron has been off, refit it with the screws no more than lightly finger tight and only finally tighten them after checking lead screw engagement at both ends of the carriage travel and that the rack and pinion operates smoothly over the full travel.<br />
<br />
== Issues and Annoyances ==<br />
As of September 2023 - mostly resolved, apart from the spindle bearings and runout, the lathe is in better condition than it has been for a number of years.<br />
<br />
===Four Jaw Chuck has two jaws too tight===<br />
Fixed 27/10/2023: Two of the chuck jaws were tight in their slots, making precise adjustment difficult due to lack of 'feel'. Moving the jaws round the slots showed the problem mostly followed the jaw not the slot. The grooves in the opposite sides of the affected jaws that run in the chuck slots were slightly out of true, and the rails either side of the slots were slightly too thick towards the center. Due to the difficulty of seeing the high spots, after cleaning up and deburring the jaws didn't do enough to ease them, I decided to grind the top of the rails where they were binding. Several repetitions of spotting with Engineer's blue, grinding, then diamond filing the high spots has eased them enough. I cleaned everything, greased the jaw slides and screws, and refitted the studs so the chuck is now fit for service.<br />
<br />
''N.B. Don't move the jaws to a different slot - the formerly tight jaws *must* stay in the slots furthest from the makers mark.''<br />
<br />
===Excessive Runout===<br />
Mostly fixed 24/10/2022: I ground the chuck seating surface of the spindle nose (outside lip) to under half a thou runout. This also cleaned up several burrs. It would be possible to do better, but that would need good spindle bearings, and a more rigid toolpost grinder mount.<br />
<br />
Our spindle nose was damaged years ago by a person with little mechanical aptitude (who shall remain nameless) beating it up with a hammer mushrooming the spindle nose. We are getting several thousandths runout at the end of the MT3 bore, a MT3 to MT2 reducer sleeve in it runs visibly out of true, as does the spindle nose flange. When you put a chuck on it, the runout is magnified by the distance from the spindle nose. Ideally we would replace the spindle when we change the bearings but its £52 [https://www.amadeal.co.uk/acatalog/4-Spindle-Upgrade-Real-Bull-Mini-lathe-CJ18-series-AMA_SP_CJ18_003RB.html#SID=9 from Amadeal] and money is tight. It may well require more work after the bearing upgrade. Once good bearings are in, if we can borrow a decent MT3 arbour as a reference, we should consider skimming the bore.<br />
<br />
===Spindle bearings===<br />
* The spindle bearings appear to be close to worn out. They are notably noisy when running, and there appears to be more slop in the spindle than is desirable. There is notable resonance around 600 RPM, and surface finish of end faces is often poor. We have some ideas for possible replacement/upgrade, but it requires a major teardown.<br />
<br />
: The original bearings are allegedly 6206-2RS or 6206-ZZ deep groove ball bearings - 2RS codes rubber seals both sides and ZZ codes metal shields. Although the deep groove gives reasonable ability to withstand axial loads, the bearing balls point contact means they are vulnerable to [https://en.wikipedia.org/wiki/Brinelling brinelling] due to shock loading. The jammed on three jaw chuck didn't help this, as before we skimmed the spindle nose lip, it had to be driven off using a bar through the spindle bore, shock loading the bearings every time. Also even a minor 'crash' could have brinelled them due to eccentric shock loading, and the lathe has previously been crashed badly enough to need drive gear replacement. There are also issues with the 'approved' method of spindle and bearing removal from the headstock brinelling them, even if you don't abuse the spindle nose with a hammer!<br />
<br />
: A possible replacement is 30206 tapered roller bearings. The new bearings are slightly thicker so the plastic spindle spacer (15) needs to be machined to length to get the 45 tooth spur gear that drives the change gears laterally aligned with the tumbler gears. If a temporary replacement (3D printed?) is fitted, the lathe can be run (without power feed capability) so this can be done on the lathe after fitting the new bearings. As tapered roller bearings have line contact, they are significantly more resistant to brinelling.<br />
<br />
: ''See [[Talk:Ian_M%27s_Lathe_Notes]] for notes, links etc. for this upgrade.''<br />
<br />
===Motor stuttering===<br />
* Fixed 21/09/2023: The motor was running very erratically and it was very difficult to set a speed. Several loose connections were found in the control box, mostly loose female spades to the motor controller board, but also a dry jointed braking resistor on the 'Filter' board, and an inhibit wire completely off its terminal on the forward/reverse switch, making intermittent contact. After tightening and/or remaking all affected connections, it was much improved but still not right below 300 RPM. The remaining issues were due to poor wiper contact in the speed control pot, and stripping it, cleaning the track and contact ring and re-tensioning the contacts resulted in the motor now running smoothly over the full speed range. The speed is slow to settle, and while part of that is probably the lag in the digital tach, I suspect that the KBIC motor speed controller isn't properly tuned as it was (allegedly) previously replaced.<br />
<br />
===Drive belt slipping===<br />
* Fixed 28/9/2022: During testing the motor after the above issue, it was noted that the chuck could be stalled, slipping the drive belt, with not much torque. The drive belt was determined to be loose and a bit worn, but still in acceptable condition. <br />
<br />
: Access for servicing the belt requires removing the control box ''(2 spades to ZVR switch disconnect the supply, speed sensor and motor simply unplug from the 'filter board')'', the motor cover, chuck guard switch assembly + wiring cover, the change gear 'A' (drive) shaft carrier assembly, and the tumbler gear assembly. See https://youtu.be/EkxlIz01BdA for disassembly/reassembly, though on our lathe, the speed encoder ring on the spindle prevents the belt cover from being fully removed without disturbing the spindle nuts. There is enough room to work with it loose, but still trapped by the encoder ring. Also, unlike the video, if the 'jack' screws under the headstock are correctly adjusted, and the studs aren't excessively bent, there is no need to make custom studs. <br />
<br />
: It turns out that our lathe was missing the M6 hex headed jack screws that press the motor down to resist the belt tension, and the motor had cocked out of position at a severe angle. I know Ian B had had considerable trouble adjusting it after the motor fault back in October 2022, and I believe it had been getting slowly worse ever since. The jack screws were probably mistaken for headstock fixing bolts during disassembly after the crash that resulted in the metal Hi/Lo gears being fitted, then lost. The penny washers on the studs had dished, so I turned them over and backed them up with smaller washers and switched to Nyloc nuts so they cant back off due to vibration. N.B. There is a packing washer on the motor side on one of the studs, presumably so the shaft is true to the ways. Adjusting the motor is awkward to say the least. One has to slack the stud nuts off a lot, pry under its rear end to lift it enough to be parallel to the ways, snug the stud nuts, check alignment, then set the jack screws and their lock nuts to hold it there, and finally tighten the stud nuts. <br />
<br />
: Tension: According to Sieg, it should be possible to twist the belt 90° mid span with a light finger grip. Other sources say 1/32" - 3/32" deflection mid span with light finger pressure.<br />
<br />
===Speed display blanking===<br />
* The speed display has been intermittent, blanking and flashing 8888 and 0 at certain speeds for as long as I have been using the lathe. Finally on 18/07/2022 it failed completely, with no display. I removed the display module and bench tested it - the pins are labelled 5V GND PL PE, PE is frame ground and PL is a TTL level pulse from the speed sensor - confirming that it was in good working order. My suspicions then turned to its power supply on the 'Filter' board. With both the sensor and display unplugged, the 5V rail was found to have a only a couple of volts, but the unreg DC was 17V and stable. Replacing the 78L05 5V regulator restored the 5V rail and normal operation.<br />
<br />
: ''I conclude its been failing for a while with high load current due to speeds with more lit segments causing it to drop out, resetting the speed display, causing it to blank, lowering the current enough for the regulator to recover, then the display MCU lamp tests (8888) then re-acquires the speed, repeating ad-nauseum till the speed is changed. I don't like the design as the high input voltage results in excessive dissipation.'' <br />
<br />
: ''ToDo: If it fails again, bench test display to measure its worst case current consumption, then fit an appropriate dropper resistor to reduce the 78L05 dissipation.''<br />
<br />
===Quill spinning when drilling===<br />
* The quill was tending to spin while drilling because its anti-rotation pin (a M5 dog tip setscrew) was sheered. I've removed the debris, aligned the scale with the top of the tailstock and fitted a longer M5 dog-tip setscrew to replace it, with a nut to lock it at the correct height. N.B. the pin isn't that 'meaty' so if using big drills in tough metals, to prevent shearing it, it should be backed out so the quill can be turned by hand and unwanted rotation controlled by being quick with the quill lock if it starts to spin, or even using a close fitting rod in one of the chuck key holes with plastic tube over it to protect the ways. <br />
: ''If the screw sheers again, the quill will need to be removed and the tailstock taken off the lathe so the sheered tip can be shaken out, and if the setscrew is difficult to remove it probably means the threads are mangled where it sheered. Try driving it right through with the quill out.''<br />
<br />
===Sloppy quick change toolpost locking mechanism===<br />
* Once the dovetail clamp screw was slackened, there was nothing preventing the dovetail twisting or cocking significantly, and friction with the toolholder made it tend to do so, making toolholder insertion and removal more difficult unless the clamping screw was backed off excessively. I added a compression spring around the clamp screw inside the toolpost to push the dovetail outwards so it mostly retains alignment when open, allowing toolholders to slide on or off cleanly with far less screw slackening.<br />
<br />
===Leadscrew rubbing===<br />
* The leadscrew shaft is rubbing on the insulating separator inside the control box. Unfortunately the corner of the relay on the Filter Control Board (#160) doesn't allow enough clearance. Although the friction isn't much of a problem at high reduction ratios, e.g. 16:1 power feed, it increases the stress on the change gear train, and may be problematic when threading at feeds above 1:1. ''Possibly pack out the control box mountings by a couple of mm.'' <br />
<br />
===High/Low lever backwards!===<br />
* The high-low drive gear selector behind the headstock is incorrectly labelled and differs from the manual: low gear (which we normally use) is with the lever towards the tailstock. ''I suspect that the gears in the headstock were refitted the wrong way round when it was upgraded to metal gears.''<br />
<br />
: ''ToDo: Get it reassembled the right way round during the spindle bearing upgrade!''<br />
<br />
===Carriage lock fouls top slide===<br />
* The T handscrew has been replaced with a M5 hex headed bolt, to permit access when the top slide is over it. An 1/4" drive 8mm socket is usually left on it, but needs to be removed when the full cross slide travel is needed. The small (4 jaw) chuck key is near enough 1/4" to use for it. If you need to (un)lock it while the compound is over it, you'll need an 8mm spanner. ''The [https://www.amadeal.co.uk/acatalog/Mini-Lathe-Carriage-Lock-463.html Amadeal lock screw] is in the spares tin as it was too high and fouled the compound slide.''<br />
<br />
===Tailstock locking lever loose===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock - See full image for key to screws]]<br />
* Diagnosed and fixed 10/1/2023 - In the base of the upper section of the tailstock, there are two dog tip set screws that engage with locating grooves in the counter-rotating shafts carrying the eccentric locking cams. They'd backed off, probably due to vibration. They need to be tightened till they bottom out in the groove, making sure they are '''in''' the groove, backed off half a turn so the shafts can turn easily, and locked in place. There's no facility to do so, so reassemble with weak threadlocker. Unfortunately to get to them you have to remove the tailstock base slide, which is held on by the pressure of four adjusting grub screws, which all need backing off, and one socket headed bolt from underneath so full tailstock realignment is required after reassembly, which even for a rough alignment is tedious.<br />
: <s>The tailstock locking lever is loose and can be pulled out on its axis. It works OK when fully pushed home but needs investigating. ''I tightened the grub screw as the lever was coming off its shaft, but the whole shaft pushes/pulls in and out. It works OK fully pushed in, but it seems something that is meant to retain it has failed inside the tailstock base.</s><br />
<br />
===Gear alignment issues===<br />
* Change gear alignment is poor. I've currently got a gapped washer (to clear the key) packing out the A shaft so the gears line up, but this reduces the key's engagement so is problematic due to the high loading if the gears are set up for coarser threads. <s>Also I need to turn down some penny washers to slightly less than the root diameter of the metal 20T pinions, as gear retaining washers.</s> ''The gear retaining washers for A gear and B-C stub shaft are now done, turned down to slightly under 16 mm dia. Spares in the change gear tin. ToDo: The D (leadscrew) washer requires a larger center hole, so make two more with that hole.'' <br />
<br />
===Saddle gibs loose===<br />
* Fixed 11/04/2023: I took the apron off for access (and to clean the carriage handwheel gears), and found the front sheer plate screws were completely loose. I've snugged them up some and set the opposing grub screws and got a lot of the slop out. I've re-checked the front ones, and taken up the slop in the rear ones - Unfortunately it wasn't possible to get carriage movement to have an even 'feel' over its whole travel, and its noticeably tighter near the tailstock. If light hand pressure on the side of the unlocked carriage can cause movement (with the half-nuts open), its time to readjust them again, though it should be possible to move the carriage with a firm push. <s>The saddle gibs (actually the sheer plates) were too loose, to the point that engaging a slightly stiff threading dial could cause it to self-feed, an obvious crash hazard if working near the chuck or a step in the work.</s><br />
<br />
''N.B. the lefthand front opposing grubscrew is short, (fully recessed) and unlike the others does *NOT* have a locking nut as it must clear the traverse pinion. A wrap of PTFE tape provides enough friction to keep it in place, though possibly a bit of nylon fishing line down its hole would be better.''<br />
<br />
===Excessive cross-slide backlash===<br />
* ''Fixed 21/11/2023.'' Originally, back in October 2023, The cross-slide screw had excessive backlash (nearly three turns), which increases the risk of loosing track of the cut depth when cutting steps, and during threading operations. If you ended up off by a turn too far in, a crash would be the most likely outcome.<br />
: The original excessive backlash was traced to loose cross-slide screw nut mountings. The nut has two socket headed cap screws pulling up, one either end, accessible from the top of the cross-slide, which control the tilt of the nut to take up backlash in the nut, and an opposing grub screw pressing down on the center of the nut to make it longitudinally rigid. Snugging up the grub screw reduced the backlash to 10 divisions or so, or 0.25 mm. A year later, the backlash had increased to one turn due to the cross-slide nut mounting screws working loose again.<br />
<br />
: 07/11/2023: I investigated further: It is difficult to get the cross-slide nut aligned correctly as it must be at the same height as the screw which is constrained by the bearing surfaces in the bracket. With the cross-slide almost at the front limit of its travel, I removed the screw and set the nut as level as possible and visually centered in the bore, then re-fitted the bracket and screw, then adjusted the tilt till it turned freely through the backlash. I then tilted it up at the front till some drag was felt to minimise the backlash and tightened the screws to lock it in place balancing them to maintain the same feel as I tightened them. The result was 7 divisions of backlash, acceptable but not great. During normal turning operations, the load on the nut is tension on the front screw and pressure on the grubscrew, so if it slackens again due to vibration from chatter, odds are it will be the rear screw that's loosened.<br />
<br />
: 16/11/2023 - 21/11/2023: The backlash had crept back up to 11 divisions (0.275 mm). We don't have any >14 mm brass stock (or even near that) so I tried making the shim washer out of aluminium. I was shooting for 0.24 mm but due to poor technique got 0.28 mm. No good - locked solid. I lapped it down and tried it till I got it down to 0.20 mm which gave about 3 divisions backlash - good enough, but the screw was too tight due to the shim washer not being bevelled at its outer edge resulting in it cupping in its seat. Filing a bevel round the OD and re-lapping it resulted in a 3 - 4 divisions of backlash. Its a little mushy due to the washer having been kinked removing it, so ideally a new (brass) washer should be made. <br />
<br />
* Further reduction of backlash: https://youtu.be/Wu_tI29JL2Y?t=163 <br />
: Brass tinned with Pb-free solder to form a white metal bearing surface should work at least as well as the bronze used in the video. The shim washer needs to be 10.2mm ID, with a full thickness bevel on a 14 mm OD. It isn't necessary to remove the lead screw from the cross slide, as the washer can be fitted in-situ with only the bracket removed.<br />
<br />
===3 Jaw chuck didn't mount properly===<br />
* Fixed 7/4/2023 by grinding the spindle nose lip. The three jaw chuck can now be installed and removed by hand with no hammering. A test bar in it now has only 2 thou runout (TIR) at the chuck.<br />
: <s>The three jaw chuck and the faceplate aren't seating properly on the spindle nose. Its too tight on the register diameter of the lip. This results in grossly excessive runout, and also makes this chuck and the faceplate a PITA to fit or remove.</s><br />
: ''The spindle nose had been abused with a hammer (before my time) which mushroomed it and may have brinelled its bearings. See '''Excessive Runout''' and '''Spindle bearings''' above.''<br />
<br />
== Manuals, Books and other resources ==<br />
=== Manuals ===<br />
The [https://wiki.richmondmakerlabs.uk/images/a/a3/Lathe_InductionNotes.pdf RML CJ18A Mini-Lathe Induction Notes]. Your mandatory Lathe Induction will cover most of this but its good to be able to refer back to it.<br />
<br />
Official [https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Amadeal CJ18A Manual], or paper copy (less complete) kept on shelf above lathe.<br />
<br />
The [https://www.chesterhobbystore.com/wp-content/uploads/2022/11/Conquest-Super-Lathe.pdf Conquest Super Lathe manual] is considerably better than the Amadeal manual and is for a near-identical machine.<br />
<br />
The [https://littlemachineshop.com/images/gallery/info/minilatheusersguide.pdf Mini Lathe User’s Guide] from LittleMachineShop.com is even more comprehensive, going into its usage in some detail, with a proper TOC, and covers both US and Metric versions of Realbull Mini-lathes. ''The only fly in the ointment is the threading section assumes a US lead screw so change gear selections and threading dial divisions will not be correct for our lathe.''<br />
<br />
[https://www.arceurotrade.co.uk/machineguides/C3-Mini-Lathe-Dismantling-and-Reassembly-Guide.pdf Sieg C3 Mini-lathe Dismantling and Reassembly Guide] "A picture story book to help you dismantle and reassemble your Sieg C3 Mini-Lathe" ''It is similar enough to ours to serve as a maintenance guide, except for the electronics, spindle drive and other headstock innards.<br />
<br />
The motor controller is a clone of a [https://acim.nidec.com/drives/kbelectronics/-/media/kbelectronics/documents/dc-drives/manuals/kbic_manual.ashx?la=en KBIC® SCR DC Motor Speed Control]<br />
<br />
=== Books ===<br />
'''Metal Turning on the Lathe''', by David A Clark, Crowood Metalworking Guides, ISBN-13: 978-1847975232 [https://www.amazon.co.uk/gp/product/B00E78RKIG Kindle Edition (£8.99)]. ''A 'free' epub can be googled for, *NOT* linked here due to dubious legality.''<br />
<br />
'''[https://archive.org/details/03screwcuttinginthelathe Screwcutting In The Lathe]''', by Martin Cleeve (a pen-name of Kenneth C Hart), Workshop Practice series #3, ISBN-13: 9780852428382<br />
<br />
'''[https://archive.org/details/15workholdinginthelathe Workholding in the Lathe]''', by 'Tubal Cain' (a pen-name of Tom Walsh), Workshop Practice series #15, Argus Books, ISBN-10: 0852429088<br />
<br />
'''[https://archive.org/details/20metalworkandmachininghintsandtips Metalwork and Machining Hints and Tips]''', by Ian Bradley, Workshop Practice series #20, ISBN-13: 9780852429471<br />
<br />
'''[https://archive.org/details/38toolandcuttersharpening Tool and Cutter Sharpening]''', by Harold Hall, Workshop Practice series #38, ISBN-13: 9781854862419<br />
<br />
'''[https://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpaperT204.pdf Cutting Fluids]''', by EC Bingham, NIST Tech. Paper No. 204, 1921<br />
<br />
=== WWW resources ===<br />
==== Mini-lathe Specific ====<br />
There's a *LOT* of mini-lathe info online. Notable sites include:<br />
* http://www.mini-lathe.com/ - A major Realbull/Sieg mini-lathe resource.<br />
* http://mikesworkshop.weebly.com/lathe-modifications.html - many mods including carriage DRO autostop, and variable speed leadscrew motor drive, cross-slide motor drive, etc. He also has a page with a bunch of accessories, toolholders etc. - http://mikesworkshop.weebly.com/lathe-accessories-and-tooling.html<br />
* http://andysmachines.weebly.com/variable-speed-controls.html - Scroll down to the 'UPDATE' section for the schematic of a very similar SCR speed control board. It also has the schematic for an earlier version of the Auxiliary Control Board (aka: 'Filter' board).<br />
<br />
==== Forums ====<br />
''with publicly accessible archives''<br />
* https://groups.io/g/7x12MiniLathe - Mini-lathe specific, active<br />
* https://www.hobby-machinist.com/forums/mini-lathe-mini-mill-information.220/ - active<br />
==== Youtube Playlists & Videos ====<br />
* Blondihacks: [https://www.youtube.com/playlist?list=PLY67-4BrEae9Ad91LPRIhcLJM9fO-HJyN Lathe Skills] (playlist) - "This is an educational series to help you learn to use your metal lathe. Watch them in order for best results! Satisfaction not guaranteed, especially if you're a cranky sort of person."<br />
* Frank Hoose (Minilathe.com) has a couple of relevant Youtube playlists:<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn7ON0jGM5UbM-KZDT56MOIp Mini Lathe Operations]<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn4nGRZaVq3wTOlvZNOmdAZ2 Mini Lathe Overview]<br />
<br />
==== General Machining ====<br />
* https://www.machiningdoctor.com/ - "THE #1 MACHINING TECHNICAL HUB"<br />
<br />
==Projects==<br />
[[File:VESA mount.jpg|thumb|Machined VESA mounting plate (left) and plate from Dell monitor stand it must match (right). The translucent washer shows the size of the original center hole.]]<br />
* My first faceplate project was boring out the center hole in a VESA mounting plate to adapt it to fit onto a surplus Dell 1708FP monitor stand. The part was centered using the tailstock dead center engaging with its original center hole. I clamped the part with studs and penny washers on the driving side of two opposite corners, with cap screws in the next slot round to trap the corners under the clamping washers, then withdrew the tailstock and dead center. After machining out the bore, I used the tip of the tool, rotating the chuck by hand, to scribe a circle for laying out the bolt holes. I finished off laying out and drilling the bolt and locating holes by hand at home, fitted it to the stand, and mounted the 2nd hand LG 24" widescreen monitor.<br />
<br />
* Another ultimately unsuccessful project was fly cutting aluminum flat bar to thickness to make custom shims for the set of carbide insert tools, for the four way toolpost. The 8 mm shank tools need ~2.5 mm shim stacks, and the 6 mm shank tools need ~4.5 mm shim stacks. Ideally I'd machine single shims, but the only stock I've got handy cleans up to only 3.2mm, and some fine shimming may be needed to fine-tune the tool height.<br />
<br />
: After sorting out the clamps so they were no longer twisting the aluminum flat bar stock, and switching to the short 45° turning SCMT06204 insert tool in the four way toolpost, to improve rigidity and get a well controlled tip radius, the finish was much improved. I'm still having problems getting an even thickness and am getting approx. 0.05mm variation, I suspect due to the aluminium bar stock distorting due to internal stresses as its surface is cut away. ''ToDo: try supergluing the stock to the faceplate before clamping to further reduce chatter and stop the warping.''<br />
: Looking back on this project a year later, its fairly obvious that the thickness variation was probably due to faceplate surface runout due to the damaged spindle nose.<br />
<br />
* Raphael has been working on a steel rocket nozzle with some assistance from myself. We have set up the rough cut chunk of ~ 50mm steel bar, faced both ends (to 50mm length) and turned the OD to 49mm to clean it up. Its going to need through drilling, probably some boring, and quite a bit of detail work on the OD. It will then need to be transferred to a jig in the drill press vice to allow a pattern of angled traverse holes to be drilled with acceptable accuracy.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_Lathe_Notes&diff=17612Ian M's Lathe Notes2024-02-07T11:34:50Z<p>IanM: /* General */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br />
<br />
''Currently these notes are semi-organized and non-authoritative. As I become more experienced with the RML CJ18A mini-lathe, I'm cleaning up, extending and reorganising them. Some lathe operating experience is assumed. If in doubt, '''*ASK*''' me, Andy H<sup>*</sup> , Jonathan H or another experienced minilathe operator!<br />
<br />
''* Andy H should be asked (for an authoritative answer) any questions involving RML usage policies or acquiring tooling or materials through RML.''<br />
<br />
== The Lathe ==<br />
Our Facilities page [[Facilities#Lathe|has]]:<br />
<blockquote><br />
'''Lathe'''<br />
[[File: Lathe2.jpg |200px|right | Lathe]]<br />
In the kitchen. <br />
<br />
Marked as a CJ18A Mini-Lathe from [[https://www.amadeal.co.uk/acatalog/CJ18A-Mini-Lathe-7x14-Machine-100mm-3jaw-Metric-With-Metal-Gears-AMA_LA_CJ18_M_3_MGRB.html Amadeal]]<br />
[[https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Manual]] <br />
<br />
[[Media:Lathe InductionNotes.pdf| Induction Document]]<br />
<br />
Possible upgrades:<br />
*https://www.youtube.com/watch?v=GwT-JQLbNPA<br />
<br />
''Please do not use the lathe until you have received induction'' <br />
<br clear=all><br />
</blockquote><br />
Its a Chinese import 7x14 mini-lathe. The 7x14 refers to the maximum diameter and length of work, in inches and is only a theoretical measure of the working envelope as you loose length to the chuck + any tailstock tooling, and the diameter is over the bed, not the cross-slide. See actual specifications below. <br />
<br />
Most if not all Chinese 7x10 to 7x16 mini-lathes seem to be remarkably similar (not uncommon with Chinese products due to [https://www.bunniestudios.com/blog/?p=284 Shanzhai (山寨)] )<br />
and the OEM of our Amadeal CJ18A Mini-Lathe was probably [https://www.made-in-china.com/showroom/cheap-lathe Yangzhou Realbull Machinery Co. Ltd]. Very similar lathes are also made by [https://www.siegind.com/lathe-machine.html Sieg], but their lathes tend to be slightly less sophisticated than the equivalent Realbull models.<br />
<br />
''N.B. Many Sieg parts are known to have slight but critical differences from Realbull parts, so '''DON'T''' order Sieg spares for a Realbull lathe!<br />
<br />
== Key Specifications ==<br />
Amadeal says the CJ18A Mini-Lathe is a 7x14 model with:<br />
<blockquote><br />
* Power 550 W<br />
* Distance between centres : 350 mm<br />
* Swing Over Bed: 180 mm<br />
* Swing Over Cross Slide: 110 mm<br />
* Taper: MT3<br />
* Tailstock Taper: MT2<br />
* Chuck diameter: 100 mm<br />
* Spindle Speed: 50 - 2500 rpm ''(with digital readout)''<br />
* Spindle Bore: 20 mm<br />
* Cross slide Travel: 65 mm<br />
* Range of Metric Threads: 0.5 - 2.5mm.<br />
</blockquote><br />
* The lead screw is metric, pitch 1.5 mm.<br />
* The spindle center is 90.6 mm above the flat of the bed (measured).<br />
<br />
Even though the compound and cross slide handwheels appear to be calibrated in thousandths of an inch, as ours is a metric machine, they only approximate that. One turn of a slide handwheel is 1mm advance, and they have 40 divisions, so each division is 0.025 mm, (approx. 0.984 [https://en.wikipedia.org/wiki/Thousandth_of_an_inch thou]). Similarly, the tailstock quill advances 1.25 mm per handwheel turn, which has 50 division dial, giving the same 0.025 mm divisions, but only 4 turns per 5 mm. The carriage handwheel is awkward - it moves approx. 19.2 mm per turn, and doesn't have a dial scale.<br />
<br />
== Notable Accessories ==<br />
We have:<br />
* [https://www.amadeal.co.uk/acatalog/160mm-Face-Plate-for-the-4-Mini-lathe-AMA_AC_CJ18A_FP160RB.html#SID=129 160 mm (6 1/4") Faceplate]<br />
* 100 mm (4") three jaw self-centering chuck (OEM standard) 22.5mm bore, with inside and outside jaw sets<br />
* 100 mm (4") four jaw (independent) chuck with reversible jaws (8 TPI screws)<br />
* Tailstock drill chuck (max. 13 mm dia.)<br />
* Live center for tailstock (+ OEM fixed center) <br />
* Four way Tool Post (OEM Standard)<br />
* [https://www.amadeal.co.uk/acatalog/Quick_Change_Tool_Post_for_the_mini-lathe.html Quick Change Tool Post] + 3 tool holders<br />
* [https://www.amadeal.co.uk/acatalog/Fixed-Steady-for-Mini-Lathes-AMA_AC_CJ18A_FSRB.html#SID=145 Fixed Steady Rest]<br />
* [https://www.amadeal.co.uk/acatalog/Travelling-Rest-for-Mini-Lathes-AMA_AC_CJ18_TSRB.html#SID=144 Travelling Steady Rest]<br />
<br />
''You'll find all of the above on the shelf above the lathe, with the accessories in the wooden box, apart from the steadies, which live next to it. Change gears, spare parts, and most cutting tool tips/blanks are in labelled white rectangular tins behind the lathe.''<br />
=== Measuring Tools ===<br />
We have:<br />
* Various dial indicators - the one with the adjustable magnetic base stand is the most convenient for most lathe setup work.<br />
* 25mm micrometer (in little grey case)<br />
* Grey case containing set of measurement tools including dial calipers, micrometer, steel rule (metric & inch), engineers square, and a fish-tail gauge<br />
<br />
''We currently lack''<br />
* ''A tool height setting gauge''<br />
<br />
=== Hand Tools ===<br />
Some common tools needed for normal use are kept with the lathe, in or attached to the wooden accessories box:<br />
* 2 mm Allen key - adjusting cross-slide and compound gibs<br />
* 4 mm Allen key - quick change toolholder tool clamping screws + height adjust, tightening dials<br />
* 5 mm Allen key - four way toolpost tool clamping screws, engaging/disengaging threading indicator<br />
* 6 mm Allen key - locking/unlocking quick change toolholder<br />
* 8 mm spanner - locking carriage when 8 mm socket can't be used, locking gib adjuster nuts <br />
* 13 mm spanner - changing chucks, locking steady rest jaws<br />
* Very long needle nose pliers - for grabbing swarf safely, holding one end of emery cloth safely so you can keep your fingers away from the jaws, and extricating small objects from awkward places.<br />
<br />
== Change Gears ==<br />
[[File:BC puller 1.jpg|thumb|Custom puller for B-C stub shaft]] [[File:BC puller 2.jpg|thumb|Pulling the B-C stub shaft]]<br />
See "Conquest Super Lathe" manual ([[#Manuals|below]]), section '''4.7 Change Gears''', PDF pages 28-29, but see below for mesh adjustment. The LittleMachineShop.com "Mini Lathe User’s Guide" (also below) section '''Threading''' gives a far better explanation, with pictures and diagrams, but its for a lathe with a US 1/16 inch pitch leadscrew, not a metric 1.5 mm pitch one like ours, so you *MUST* ignore all the tables in that section, replacing them with metric mini-lathe (with 1.5 mm pitch leadscrew) equivalents. <br />
<br />
We have the following tooth count gears: 20,20, 30, 35, 40,40, 45, 50,50, 60,60, 80,80<br />
which consist of the OEM power feed gears + the metric change gear set. Apart from the metal 20 tooth pinions, they are all plastic, probably Delrin if the molded in 'POM' marking can be trusted, but possibly plain Nylon 6, and are metric Module 1.<br />
<br />
If we wanted to add the capability to cut US/Imperial threads we'd need to buy additional 55, 57 and 65 tooth gears, and possibly a 21 tooth metal pinion.<br />
<br />
CGTK's [https://www.cgtk.co.uk/metalwork/calculators/changegears/minilathe?gears1=20,20,30,35,40,40,45&gears2=50,50,60,60,80,80&gears3= Change Gear Calculator] ''(link preloaded with our gear list)'' is useful if you don't want to calculate the ratios from first principles. Not all suggested combos will physically fit.<br />
<br />
* Take care *NOT* to loose the keys in the A and D shaft keyways - turn each shaft till the keyway is up before removing the gear. <br />
* The B and C gears are coupled by a hollow stub shaft (with an integral key), which is so tight in the gears it has to be pressed or driven out - I've made a puller just for this task, kept in the change gears tin.<br />
* The center of the B-C stub shaft *MUST* be lubricated where it runs on its pin on the change gear banjo bracket, with grease or heavy oil. ''Seizure of the stub shaft due to running dry is a frequent cause of catastrophic mini-lathe geartrain failures!''<br />
* Don't get oil on the change gears as it can cause plastic gears to crack. Only PTFE drylube or plastic compatible white grease should be used on their teeth. <br />
* Adjust the B-C pin position in the straight slot first to set the C to D gear mesh, tighten its nut, then swing the whole banjo about the D shaft boss to set the A to B mesh, and finally tighten the banjo clamping nut.<br />
* Check both gear meshes have running clearance by turning the chuck by hand enough to complete one full turn of the leadscrew, and by attempting to turn the intermediate gear(s) to assess backlash, If excessive resistance is felt or if there's significant backlash, readjust the gears. If you have difficulty judging the mesh, a strip of 80 gsm copier paper (approx. 0.1 mm thick) wound into the meshing teeth before tightening the stud or banjo will give appropriate clearance once removed. Once setup, check the gears run quietly under power.<br />
* If the sum of the tooth counts C+D is the same as for the ones you just removed and they were correctly meshed, you don't need to move the stub shaft pin. If A+B is <u>also</u> the same, you don't need to move the banjo. e.g. If it was set up for 16:1 reduction power feed, 1 mm (40:60 - 50:50) for M6 and 1.5 mm (e.g. 40:60:40) for M10 pitches can thus be achieved by only swapping gears. <br />
<br />
''The change gears, puller, etc. and a box spanner for the banjo nut are kept in a white rectangular tin behind the lathe.''<br />
<br />
=== Power Feed ===<br />
When used for turning with power feed, the change gears should be set for a 16:1 reduction (A:20 : B:80 - C:20 : D:80) using the pair of small metal 20 tooth pinions and the 80 tooth plastic gears (largest in set), for a feed of 0.09375 mm per turn (1.5 mm/16). Unless continuing your threading project the next session, please re-fit the 16:1 power feed set after threading so the power feed is ready for use. <br />
<br />
* *ALWAYS* leave the feed direction selector lever in its neutral (no feed) position, and the half-nuts open after use.<br />
* *ALWAYS* check the carriage lock is disengaged before engaging power feed. Unlock the carriage after use. <br />
<br />
=== Threading Dial ===<br />
The threading dial is an aid to re-engaging the half-nuts at the right moment so the tool will retrace its previous path cutting deeper, rather than offsetting axially some fraction of the thread pitch and ruining your work. Its based on the concept of the lowest integer multiples of the leadscrew and thread ''(being cut)'' pitches that exactly match, but for mechanical simplicity it only covers certain selected multiples of the leadscrew pitch.<br />
<br />
We have a choice of three pinion gears:<br />
{| class=wikitable<br />
|+ Threading dial Pinion Gears<br />
|-<br />
! Teeth !! Colour Dot !! Usable lines !! OD gear !! Dist. per turn<br />
|-<br />
| 14 || Red || 1,7 || 7.51 mm || 21 mm<br />
|-<br />
| 15 || Orange || 1,5,9 || 8.05 mm || 22.5 mm<br />
|-<br />
| 16 || Green || 1,4,7,10 || 8.37 mm || 24 mm (2 mm/div)<br />
|}<br />
They are now colour coded, with a paint dot on the gear end face ''(the only non-wear surface)''. The 16 tooth one is normally left on the lathe, but disengaged when not threading to minimise wear on the lead screw. The others are kept in the Change Gear tin.<br />
<br />
There's a threading dial 'pickup' calculator here: https://www.cgtk.co.uk/metalwork/calculators/threaddialindicator <br />
<br />
Initially select ''Lathe:'' '''Custom''', and enter the following below:<br />
* ''Units:'' '''Metric'''<br />
* ''Lead Screw Pitch (mm):'' '''1.5'''<br />
* ''Thread Dial Indicator Gear Teeth:'' '''16,15,14''' <br />
* ''Lines on Thread Dial Indicator:'' '''12''' <br />
* ''Line Marking:'' '''Every Line Numbered'''<br />
Note the teeth list is entered in reverse order so the resulting table highlights any required pinion changes.<br />
<br />
N.B. The dial is only friction clamped to the pinion by its center screw. If you have any reason to suspect it may not be properly aligned: <br />
# With the power off and the carriage unlocked, engage the feed direction lever upwards. You'll probably need to turn the chuck by hand to get it to engage.<br />
# If the threading indicator isn't already engaged, loosen the threading dial support block bolt, pivot the block to engage the pinion with the leadscrew and retighten the bolt.<br />
# Engage the half nuts, again turning the chuck by hand till they drop in. <br />
# Turn the chuck a couple of turns, top towards you to take up any backlash, then lock the carriage, taking care not to push it left while locking it.<br />
# Loosen the screw securing the dial to the pinion.<br />
# Align the '1' line of the dial with the index line, by rotating the dial clockwise, then retighten the screw.<br />
# Don't forget to disengage half-nuts and unlock the carriage!<br />
<br />
The above instructions should result in the half-nuts engaging cleanly when exactly on any valid line when threading towards the headstock. If it is required to thread away from the headstock, there will be a slight offset from the line due to backlash between the spindle gear and leadscrew, so engage slightly early.<br />
<br />
Changing the pinion:<br />
# Loosen the threading dial support block bolt and disengage from the leadscrew.<br />
# Undo dial center screw, and remove it and the dial, dropping the old pinion out the bottom.<br />
# Oil the shaft of the new pinion with a drop of light oil and insert it from below, gear end down.<br />
# Refit dial and screw.<br />
# Check the dial and pinion turn freely with minimal resistance.<br />
# Align as above.<br />
<br />
== Tailstock and Steadies ==<br />
These are mostly used to support long work ''(long with respect to its diameter)'' to improve rigidity, increasing accuracy and reducing chatter. The Tailstock quill is also used with a drill chuck for drilling.<br />
=== Tailstock ===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock base]]<br />
The tailstock can be offset to turn shallow tapers between centers. We don't currently have the accessories to turn between centers, namely <s>a MT3 dead center for the spindle, or</s> any drive dogs for the work. Also realigning the tailstock after turning a taper can be a PITA. The photo shows the tailstock adjusting screw locations ''(C - Lateral, and D - Skew)'' and the block on the baseplate they engage with. Adjustments can only take effect when the tailstock locking lever is eased to take the pressure off the baseplate. As we don't have a MT3 center, one has to turn a fresh point on a test workpiece for a rough tailstock alignment reference. Fine alignment, to avoid inadvertent taper turning, can be done by mounting a long precision ground bar between the chuck (or preferably a center in the spindle), and a dead center in the tailstock and sweeping it with a dial indicator on the carriage. Finally a test cut should be taken at either end of a bar between centers, and the diameters checked with a micrometer. Assuming the bed has previously been properly levelled and shimmed to take out twist ''(not the case at RML as we don't have it bolted down)'', any remaining difference in diameter will be double the tailstock offset, smaller at the tailstock being offset towards the front. Fine adjustment cant be achieved by jacking with the screws, its best to ease the adjusting screws, bump the tailstock into alignment then take up the screws again, checking the alignment is maintained when the tailstock is unlocked and relocked. There is no vertical adjustment, though shims can be added between the tailstock and its base.<br />
<br />
==== Tailstock Quill ====<br />
There is a metric/imperial scale on the top of the quill, read against the end of the tailstock, for depth measurement when drilling. The tailstock quill has a 1.25 mm pitch thread and a 50 division dial. Each division is therefore 0.025 mm, and it only takes 4 full turns of the handwheel to move the quill 5 mm. <br />
<br />
To eject MT2 taper tooling and centers from the tailstock, wind the quill all the way in.<br />
<br />
N.B. The quill anti-rotation pin (dog-tip setscrew + locking nut in top of tailstock near to the quill lock) is only M5. It will sheer if a large diameter drill jams in the work. Please back it out clear of its keyway if using large drills, and use alternative methods of preventing chuck rotation. To re-engage it, crank the quill out till you can see the keyway, align it with the screw and screw in the screw till it gently bottoms out, then back it off a quarter turn. Try twisting the quill to check its properly engaged, then tighten the locking nut gently to hold the screw in position clear of the bottom of the keyway.<br />
<br />
=== Steady Rests ===<br />
We have two, both with brass tips that must be kept lubricated during use.<br />
<br />
The fixed steady mounts on the ways, and is most useful when turning longer work that wont fit through the spindle bore. Adjustment is critical, and the surface the tips run on must be smooth and concentric, as any misalignment that forces the work off center will result in the work wobbling in the chuck, marring it, with a high risk of it becoming un-chucked, which can be dangerous at speed.<br />
<br />
The travelling steady mounts to the headstock side of the carriage to locally resist the deflection of thin long work, due to the cutting forces. It only has two tips, to resist climb, and deflection away from the tool, and requires readjustment after every cutting pass.<br />
<br />
== Tooling and Tool Holders ==<br />
'''Key dimensional data:'''<br />
* The quick change holders accept up to 10 mm shank tools. <br />
* The four way toolpost has 50 mm long sides, a seat width of 15 mm and can clamp tools of up to 5/8" (15.875 mm) shank ''(check this)'', but the slot base is only 10.4 mm below the spindle center so cannot be used with >10 mm shank tooling unless it has a dropped tip. Large tooling with a centered tip is also problematic as you run out of height above the shank when trying to shim to match the spindle center height. <br />
<br />
===Quick Change Toolpost===<br />
I've got the quick change toolpost and toolholders setup for mostly easy use. The three toolholders came with cantilever height setting arms which historically haven't been installed as the supplied fixing screws were too short. That's all now sorted out and a HSS RH turning tool and a HSS hand-ground grooving/parting-off tool are now mounted in two of the holders and set to height. The third is kept free for other tools. <br />
<br />
The quick change toolpost has been modified with a spring to press the dovetail clamp outwards and help stop it twisting or flopping about to ease toolholder fitting and removal. The dovetail clamp (socket headed screw on toolpost side opposite dovetail) feels a bit stiffer than before, but will take less than half a turn to go from open (with the toolholder lifting out or dropping in easily) to fully clamped. As there is so much less clearance in the open position you should no longer need to wiggle the toolholder while clamping it to get a consistent height. If the dovetail clamp ever gets misaligned, twist it straight by eye, slacken off a bit further than usual to get a toolholder on, clamp it to align the dovetail then release, reseat the toolholder and re-clamp to ensure its at its preset height. You cant adjust the height by 'jacking' with the height screw due to its offset leverage. Instead, back off the height screw and hold the toolholder at the desired height while locking the dovetail clamp, then adjust the height screw (and locking nut) to hold it there, then check it doesnt change height significantly when you unclamp and reclamp the dovetail. <br />
<br />
Unfortunately the OEM height setting screws foul the toolpost locking nut handle. Currently, if you need to swap toolposts you will have to first remove the quick-change tool holder from the post. There is enough nut handle swing to allow the quick change toolpost to be unclamped and rotated to fine set the tool angle without removing the toolholder. It also seems the mating surfaces may be slightly out of square, as if you rotate the toolpost 90° or 180°, the nut swing may be insufficient to re-clamp it without removing the toolholder to do so. Add a M10 washer under the locking nut if the handle ends up pointing in an undesirable direction! A thin M10 washer is kept with the toolpost collar for this purpose, and will shift the handle position by about a third of a turn. <br />
<br />
''ToDo: Make a taller nut of a similar pattern, to clear the height setting screws.''<br />
<br />
===Four Way Toolpost===<br />
The OEM four way toolpost is significantly more rigid than the quick change toolpost + holders because it has fewer and thicker parts and less overhang. Therefore the four way toolpost should be used when using carbide tooling. It requires shimming under the tool to set the tip height to the spindle center height - see below. The tool shanks are mostly significantly less than 15 mm wide, so need to be centered under its clamping screws, tempting as it is push the shank in for full side contact with the toolpost. If possible clamp the shank with all three screws not just two.<br />
<br />
==== Shimming ====<br />
We typically only mount up to two tools, and want maximum rigidity, so use 50 mm x 15 mm shims, (the full seat area), preferably with deburred edges and radiused corners so they aren't a hazard to the operator.<br />
<br />
We have pre-cut and marked shims of the following thicknesses: <br />
* 1x 3.23 mm, 2.42 mm, 1.56 mm, 0.32 mm, and 0.25 mm<br />
* 2x 1.00 mm, 0.77 mm, 0.12 mm, 0.11 mm, 0.10 mm and 0.05 mm<br />
* 4x 0.53 mm<br />
<br />
Our shims are mostly found materials (hence the awkward thicknesses) and are mostly a mixture of aluminium and steel, with a couple of GRP ones. The toolpost seat '''<u>must be absolutely clean</u>''' to avoid embedding debris in the aluminium or GRP shims, to get a consistent height and avoid tilting the tool - wipe it every time you change a tool! Put the thin shims at the bottom of the stack to avoid the tool shank edges creasing them. Shims are kept in a little yellow plastic box with a clear lid, near the carbide tools case.<br />
<br />
I made a tool height setting gauge (T shaped black acrylic with steps in its sides) which can be used to check the tool tip height matches the spindle center height using either the flat of the ways or the saddle as a reference. The tool tip should just fit under the lip of the appropriate step, with the T arms across the ways flats or on the saddle. It is kept in the box with the carbide insert tools.<br />
<br />
''ToDo:'' <br />
<br />
* ''Cut more shims neatly, mark them with their thickness.''<br />
* <s>''Do test cuts and start noting shim stack-ups for various tools.''</s><br />
* ''Organise shim storage!''<br />
<br />
=== HSS Tools ===<br />
[[File:Tool Bit Geometry.jpeg|thumb|Single point cutting tool geometry]]<br />
Our HSS tools are made from 8 mm square bar stock, hand-ground to tip profile in-house. See LittleMachineShop's [https://littlemachineshop.com/images/gallery/instructions/grindingtoolbits.pdf Grinding Tool Bits] notes. <br />
<br />
I've installed our usual HSS LH turning and parting off tools in two of the quick change holders and set the heights correctly. There are a couple of other HSS tools or tool blanks knocking about. Taking heavy cuts turning steel (even with good cutting oil) blunts HSS tools fairly quickly, which are time-consuming to re-sharpen nicely without a dedicated tool & cutter grinder with appropriate jigs. Its worth noting that the usual 'speeds & feeds' tables are commonly based on surface speeds expected to give a half hour (active cutting) tool life before resharpening.<br />
<br />
I touched up the LH turning tool by lapping on wet & dry (silicon carbide) paper on glass (Aka: [https://en.wikipedia.org/wiki/Scary_sharp 'Scary Sharp']) working upwards through the grits 200, 400, 600 and finally 1000, initially 'bluing' the surfaces to be lapped with a marker pen to see which areas needed taking down more. The end of the tool was significantly uneven so I touched that up freehand on the bench grinder to flatten it when it became apparent that 200 grit lapping wasn't cutting where it needed to. There was an existing micro-bevel on the leading side, which I kept. Finally I 'dubbed' the leading corner vertical edge on the 1000 grit to give it a very slight nose radius. A test cut on brass gave a very nice finish when turning.<br />
<br />
''Ian B has purchased some spare 8mm HSS tool blanks - talk to a lathe trainer if your proposed lathe work needs custom ground HSS tooling.'''<br />
<br />
=== Brazed Tungsten Carbide Tools ===<br />
Somewhat of a half-way house between hand ground HSS tooling and insert tooling with the disadvantages of both and some more besides - e.g. they are much harder to sharpen. So why do we bother? Some tool geometries would be awkward and tedious to hand grind, and Chinese import brazed carbide tooling is about half the price of similar HSS tooling, and far more readily available. Also, for space constrained tooling like boring bars, if you want carbide, for insert tooling, the size of the insert and its clamping seriously limits the minimum hole diameter you can work in. I have purchased a set of 3/8" shank brazed carbide tipped boring bars, but we currently cant sharpen them, due to lack of a diamond grinding wheel. <br />
<br />
=== Tungsten Carbide Insert Tools===<br />
Decoding ISO insert tooling part numbers: https://www.cutwel.co.uk/blog/learn-the-turning-tool-iso-code-system<br />
[[File:Carbide set.jpg|800px|thumb|left|Our set of Tungsten carbide insert lathe tools (before the new inserts were fitted)]]<br />
<br />
{| class=wikitable<br />
|+ Tools, left to right, (+ last across top):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| SSKCR0610H06 || 75° through boring || SCMT06204 || Long || 6 || 6.34 || ''4.33''<br />
|-<br />
| SSSCR0610H06 || 45° deep facing, internal chamfering || SCMT06204 || Long || 6 || 6.13 || ''4.58''<br />
|-<br />
| SWUCR0610H05 || 93° boring, deep facing || WCMT050308 || Long || 6 || 6.22 || ''4.48''<br />
|-<br />
| SWGCR0810E05 || 90° RH turning & facing || WCMT050308 || Short || 8 || 8.25 || '''2.45'''<br />
|-<br />
| SSSCR0610E06 || 45° turning, chamfering || SCMT06204 || Short || 8 || 8.75 || ''1.93''<br />
|-<br />
| SSBCR0610E06 || 75° RH turning, chamfering || SCMT06204 || Short || 8 || 8.72 || ''1.98''<br />
|-<br />
| LW0810R-04 || 60° external threading || JCL15-120 || Short || 8 || 7.44 * || ''3.28''<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || 8.23 || ''2.5 ?''<br />
|-<br />
| LN0813R-04 || 60° internal threading || JCL15-120 || Long || 7.95 || 7.44 * || ''3.28''<br />
|}<br />
<br />
{| class=wikitable<br />
|+ More Tools, (loose in tin):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || ~8.5 (not in use) ||<br />
|-<br />
| [https://www.glanze.co.uk/product/glanze-12-mm-60-degree-metric-internal-threading-tool/ Glanse SIR0012K11] || 60° internal threading bar || 11IRA60 || Long || 12 dia || ??? || ???<br />
|}<br />
''Shim stack heights in bold are tested, in italic are only calculated.'' ''Tip heights marked * are with new JCL15-120I inserts. The single remaining plain JCL15-120 insert has a slightly higher tip height.''<br />
<br />
Carbide tooling typically requires two to three times more speed than HSS and at least a couple of 'thou' depth of cut for best results.<br />
<br />
Chatter can rapidly kill carbide tooling by chipping the cutting edge. To improve rigidity and reduce the risk of chatter, the cross-slide and compound gib screws need to be well adjusted so there is minimal play in the slides, tool stick-out should be minimised, the four way toolpost should be kept over the cross-slide, and the work should be kept close to the chuck (or otherwise supported by tailstock or steady rest) to avoid excessive deflection.<br />
<br />
Thermal shock is almost instant death to carbide, and when dry cutting the insert tip can run very hot, so do not add extra cutting fluid manually during the cut. Pre-apply what you need, evenly, before starting the cut.<br />
<br />
Parting off or facing to center is high risk - if the tool tip is even slightly below center or if tool or work deflection takes it below center, the work will tend to climb over the tool tip as the cut approaches center, breaking the insert. To avoid this, the tool should be shimmed slightly above center, sufficient to allow for work and tool deflection, and unless very close to the chuck, a steady should be used. Its often preferable to part to a couple of mm dia. remaining then stop and saw through the remainder. Parting off hollow parts is much lower risk.<br />
<br />
Further investigation of the Tungsten carbide insert tool height situation is not encouraging - the so-called 'set' in question does not have a consistent tip height ''(see above table)''! In a real set, the insert seats *should* be machined allowing for the insert thickness to bring all the cutting edges to the same height with respect to the shank underside. However if you place them tip to tip on a table its easy to see there is considerable height variation, so they need to be individually shimmed (or at best, one machined shim will only be right for two or three tools). At this time we don't have dedicated shim stacks for each tool.<br />
<br />
A 2.42 mm thick shim brings the SWGCR0810E05 90° RH turning & facing tool almost exactly to center height, and good results were obtained turning 1" steel pipe. However facing 50mm steel bar stock to center found it to be slightly low, leaving a fractionally under 0.05 mm 'pip' so it needs another 0.03 mm to bring it fractionally above center. Fractionally too high is generally preferable to fractionally too low, due to tool deflection, so adding an 0.05 mm shim to the stack should produce optimum results.<br />
<br />
==== Inserts ====<br />
Ian B has purchased the spare inserts we needed in sets of five. He even was able to get the CK3 parting-off inserts which had been difficult to source!<br />
<br />
Inserts used in above tool set:<br />
* 3x SCMT06204 (square, indexable) https://www.rdgtools.co.uk/acatalog/SCMT-06-Carbide-Insert.html<br />
* 2x WCMT050308 (triangular, indexable) https://www.rdgtools.co.uk/acatalog/WCMT-05-T3-08-5XTIP-8813.html<br />
* 2x JCL15-120 (60 deg threading point) https://www.rdgtools.co.uk/acatalog/X5-JCL-15-120L-THREADING-TIPS-60-DEGREE--X5-TIP---23455.html<br />
* CK3 (parting off) https://www.rdgtools.co.uk/acatalog/CK3-CARBIDE-TIPS---PARTING--BOX-OF-5PCS--9437.html<br />
<br />
Inserts used in other tools:<br />
* 1x CK3 (as above) also missing from spare parting off tool<br />
* 1x 11IRA60 in Glanse threading bar + 1x spare<br />
<br />
=== Drills ===<br />
Various sizes of center drills are kept in a plastic bag next to the wooden accessories tray. There's also a small box of 2.5 mm center drills.<br />
<br />
We have a set of 11 TiN coated HSS drill bits from 1.5 to 8 mm, (in a cylindrical plastic index box) for tailstock drilling of brass, aluminium and non-abrasive plastics. To keep them sharp enough for the precision work we expect from the lathe, please don't use them for steel or reinforced plastics, and don't borrow them for non-lathe use. Metric and US [https://littlemachineshop.com/reference/numberdrillsize.php numbered]/[https://littlemachineshop.com/reference/letterdrillsize.php lettered] general use HSS drill bits are kept in two red metal index boxes next to the drill press.<br />
<br />
== Using the Lathe ==<br />
=== General ===<br />
Making dimensioned parts is primarily done by touching off the tool tip on a reference surface (with the lathe stopped, turning the chuck by hand), zeroing the handwheel dial, then manually counting turns and divisions. When backing off the tool its best to do so by exactly one whole turn so you don't forget the previous dial position. Stopping and measuring the work before taking the final cuts is essential if high accuracy is required. ''I've changed out the dial setscrews for flat tip ones with a tiny slug of solder under them so the dials are now friction fit on their shafts. i.e. if you hold the handle firmly taking up the backlash in the direction of cut, you can zero the dial just by grabbing and twisting it.''<br />
<br />
Carriage movement is less easy to measure as the handwheel is uncalibrated and advances an awkward bit over 19.2 mm per turn. Your options here when shoulders or other features must be exactly positioned are, in order of increasing accuracy: <br />
* Use measuring instruments, scribe the work at the desired length then work to the scribed line. Its often convenient to black the work with a permanent marker, then scribe with the tool tip, turning the chuck by hand.<br />
* for short distances, lock the carriage and use the compound, set parallel to the work<br />
* Set up a long travel dial indicator to measure carriage motion. <br />
N.B. with the leadscrew stopped, and the threading dial engaged, with its default 16 tooth gear, it will make one turn for every 24 mm of carriage movement (2 mm/div). This isn't accurate enough for positioning but is sufficient to check you aren't out by a whole mm or more.<br />
<br />
Do not allow any solvents to contact the chuck guard clear plastic as it will make the plastic brittle, or even craze it, and try to avoid melting it with the work light!<br />
<br />
===Speeds & Feeds===<br />
A cutting speed chart for HSS tooling, published by Model Engineer magazine can be found [https://www.model-engineer.co.uk/sites/7/documents/cutting%20speed%20chart.pdf [here<nowiki>]</nowiki>]. The second row is the target feed rate and the rest of the chart, apart from the diameter column is RPM.<br />
<br />
For carbide tooling cutting iron and steels, recommended speeds are generally three times higher than for HSS, but the CJ18A 2500 RPM max. spindle speed (in high gear) means you can only reach the optimum speed range for over 15 mm dia work. For small diameter work, HSS tooling may well be a better choice.<br />
<br />
An online metric speeds calculator is here: https://www.cgtk.co.uk/metalwork/calculators/cuttingspeeds <br />
<br />
How to do the maths to calculate speeds and feeds: https://www.cutwel.co.uk/blog/speeds-feeds-made-easy<br />
<br />
If you can hear the lathe 'sing' as it cuts, you are getting chatter, which invariably results in poor surface finish. Try decreasing (or possibly increasing) the spindle speed till the resonance stops. <br />
<br />
Once you have a wavy surface due to chatter, a light cut wont clean it up as the tool 'twangs' from peak to peak. You have to take a deep enough cut to get under it. For precision parts, its therefore desirable to take a trial finish cut while still 0.5 mm or so oversize, to give an opportunity to tweak the cut to get a good finish, check for taper, and that the part wont be undersize (on your test finish cut nominal diameter).<br />
<br />
=== Slide Locks ===<br />
* The carriage can be locked to the ways using the M5 hex screw through the top of the saddle to the left of the cross-slide. Double check the leadscrew is disengaged and the half-nuts open before locking it. Lock it when facing.<br />
* The cross slide can be locked by a M4 socket headed cap screw just in front of its middle gib screw. Locking the cross slide is helpful when turning very shallow conical features where the cross slide handle is in the way of the compound.<br />
* The compound slide can be locked by a M4 socket headed cap screw in line with the edge of the toolpost mount on the side with the gib adjustment screws. In normal use it should be kept backed off half a turn but it is desirable to tighten it for parting off operations to keep the resulting end faces flat.<br />
<br />
=== Chucks and Chuck Jaws ===<br />
==== Terminology ====<br />
* Inside jaws have steps on the outside to grip the ID of hollow work, but can also be used as outside jaws on small diameter parts (i.e. that fit through the spindle). <br />
* Outside jaws have steps on the inside to grip the OD of the work.<br />
* Universal chucks have a scroll plate with a spiral screw thread that moves all the jaws.<br />
* Independent chucks have individual adjusting screws for each jaw.<br />
<br />
==== The Chucks ====<br />
* The three jaw universal chuck can only grip near round or hexagonal work, which it centers, but its concentricity is not perfect so e.g. if you reverse the work and continue turning at the same diameter from the other end, you will see a line where the turned surfaces meet. It has separate sets of inside and outside jaws, and we normally keep the inside set installed to use as outside jaws for small diameter work.<br />
<br />
** Our jaws are individually numbered, stamped in the groove. They must be fitted in the correct sequence. The jaw slots are not clearly marked. Lowest runout for small dia. parts is achieved if you fit the jaws with #1 anticlockwise of the makers mark, then continue anticlockwise for #2 and #3.<br />
** A large strong rubber band is a great help getting all the jaws started on the scroll together - with slots #1 and #3 above the centerline and the scroll thread outer tip between #1 and #3, insert jaws #1 and #2 and put the rubber band round them to keep them in their slots. Insert jaw #3 and stretch the rubber band over it to hold it up into its slot. If the scroll was positioned correctly, all jaws should be at the same initial radius. The jaws can now be cranked in with the chuck key and they should all engage in step so they meet in the middle.<br />
:: ''Mini-lathe.com have the best instructions for [https://www.mini-lathe.com/mini_lathe/chucks/chucks.htm#Installing_Chuck_Jaws changing the jaws].'' <br />
<br />
* The four independent jaw chuck can grip most roundish or squarish work, which can either be carefully centered by the user, or deliberately gripped off-center. <br />
** Its jaws are reversible so can be swapped from inside to outside by simply cranking each jaw out and reinserting it the other way round, one at a time. DON'T move the jaws to different slots as they are likely to bind.<br />
** When setting up to face the sides of rectangular objects held crossways, it may be helpful to use both inside and outside jaw orientations, in symmetrical opposing pairs.<br />
** Its screws move their jaw 1/8" (3.125 mm) per turn<br />
<br />
* The jaws must '''never''' protrude from the chuck OD by more than one step, and for safety, its preferable they don't protrude at all, as they make the gap between the front of the bed and the chuck body an even more unforgiving meat grinder, and as the number of teeth engaged with the scroll or screw decreases, they loose strength, just when you need it the most to grip larger/heavier work. <br />
<br />
''Neither chuck is well suited to gripping tapered work safely. When seating work that doesn't quite fit through the chuck bore (which is larger than the 20mm spindle bore limit), be careful that it isn't seating on the chamfered edge of the chuck bore as it is far to easy to get the work slightly cocked so it doesn't run true.''<br />
<br />
==== Changing Chucks ====<br />
* When changing chucks, use the small grey plastic mat to protect the ways under the jaws in case you drop the chuck.<br />
* The spindle nose has two patterns of holes - the three hole pattern is for the three jaw chuck and the faceplate, and the four hole pattern is for the four jaw chuck. One hole is shared between the patterns, and is marked on the spindle nose.<br />
* To fit a chuck:<br />
** First check that the spindle nose and chuck back and recess are free of swarf, grit or other debris. Any foreign objects will tilt the chuck causing excessive runout and may mar the surfaces.<br />
** Remove the nuts and split lock washers from its studs, line its studs up with the hole pattern (preferably with the stud nearest anticlockwise to the makers mark through the marked spindle hole), fit and hold it in place with your right hand, and with your left, get the lock washer and nut on the top stud, and take up the slack.<br />
** One one nut is on, you no longer have to worry about dropping it, and can work round fitting the remaining washers and nuts, taking up the slack on each as you fit it. <br />
** Next, work round again getting them all finger tight, then tighten them gently, and finally work round fully tightening them. <br />
* Removal is the reverse of refitting. Put the washers and nuts back on the chuck's studs so they don't get lost.<br />
<br />
==== Gripping Threaded Work ====<br />
It is generally undesirable to chuck work gripped on a screw thread, as it is difficult to hold the work securely and get good concentricity while avoiding crushing the thread crests. However, if one must, one of the better ways of doing so is to wind a wire helix to fit the thread then clamp on the outside of the wire so it seats on the flanks of the thread. The wire should be mild steel or soft iron for steel parts and copper for aluminium and brass parts, single strand, round and of uniform diameter a little less than the thread pitch. It can be wound on the lathe, in reverse, by chucking a sacrificial mandrel of the same diameter and thread pitch, hooking the end of the wire round or under the jaw, against the direction of rotation, then holding the other end of the wire under tension with pliers and starting the lathe dead slow. Once wound and removed from the mandrel, the ends must be trimmed then it should be screwed on to the threaded work to provide a surface to chuck on.<br />
<br />
=== Faceplate Work ===<br />
Faceplate work is probably the most dangerous operation you can (or rather should) perform on a lathe. The working area is a large diameter spinning surface with protruding clamps to fixture the part that it is impractical to guard. Protruding clamps, studs, nuts etc. are very difficult to see at speed.<br />
<br />
'''Treat the faceplate with great respect and caution if you wish to continue to be able to count to ten on your fingers!''' <br />
<br />
The 65 mm cross-slide travel vs the 80 mm faceplate radius is a serious limitation that may require creative compound, toolpost and tool setups for larger parts, and doing full face cuts in two sections.<br />
<br />
''It is common practice to skim the faceplate to ensure it runs true. We have not (yet) done this, and wont till the spindle is in better bearings and the nose reground to minimise runout.''<br />
<br />
==== Clamping ====<br />
Open ended/sided clamps should be oriented so that cutting forces drive the work towards the clamping bolt/stud, not out from under the clamp. Minimize the protruding length of thread past the clamping nut, if necessary using sacrificial bolts or studs you can cut to length, or even using a long M8 stud for one of the faceplate mountings, so you can get a clamp nearer to the faceplate center. Double-check all clamps are secure, manually turn the faceplate to check the work and clamps clear the ways, top-slide and toolpost, and stand out of the 'line of fire' (a disc extending from the faceplate) when spinning up the work for the first time. <br />
<br />
If you need to machine close to a clamp, consider marking a safe limit circle on the faceplate and work with a marker pen to make it easier to see how close the cutting tool is to crash disaster. <br />
<br />
I strongly advise reading chapter two of Tubal Cain's book "Workholding in the Lathe" several times before your first faceplate setup, and if possible get another experienced lathe user to check your first few setups before spinning them up.<br />
<br />
==== Chuck Guard Removal ====<br />
The faceplate is too large diameter to fit under the chuck guard, but the guard has an interlock switch wqhich must be closed for the lathe to run. The guard is now fitted with wing nuts so it can be removed allowing the the interlock switch to close when using the faceplate. It *SHOULD* *ALWAYS* be refitted if a chuck is fitted, except when turning work too large to clear the guard. <br />
<br />
''The chuck guard is primarily there to make it very difficult to start the lathe without removing the chuck key and to reduce the area of large diameter spinning surface exposed. It may slow down the projectile if a chuck sheds a jaw but is unlikely to stop it. Also it serves to contain coolant spray spun off the chuck. As we don't use flood coolant this usually isn't an issue for us. As setting up for faceplate work doesn't use a chuck key, and the most hazardous zone is the face of the faceplate, with its spinning projecting clamps, with full access required for machining operations, which a guard would not cover, the consensus is that removing the guard is an acceptable risk.''<br />
<br />
=== Turning and Facing ===<br />
We are getting good results in aluminium, brass, and even steel using HSS cutting tools in quick-change tool holders, and the ~ 94 um/turn power feed. Unfortunately due to lack of rigidity in both the machine and smaller diameter parts, if you don't want the outer end to be over diameter, a light final cut and multiple 'spring' passes will probably be required.<br />
<br />
For aluminium, a sharp HSS tool and 0.5 mm (20 div) depth of cut gives good results with power feed for rapid stock removal. Its also easy maths as each cut takes ~ 1 mm off the diameter. Finish cuts should be much finer, 0.1 mm (4 div) is 'in the ballpark'.<br />
<br />
For steel, using carbide insert tooling, a 0.25 mm (10 div) depth of cut is more appropriate, and with pre-applied cutting oil, gives reasonable results with power feed if you use enough speed. The maths is not quite so easy as you are only taking 0.5 mm off the diameter per pass. Again, use finer finish cuts but try to plan your cuts so the final cut is still cutting, not smearing the surface!<br />
<br />
When facing or parting off, some skill is required to turn the cross-slide handwheel steadily to get a decent finish and to avoid shock-loading the tool tip. Increasing the spindle speed in one or more steps to keep up with the reducing diameter is advisable, but avoid speeds that cause resonances (resulting in chatter). When parting off, small through-hole parts may be caught on a thin rod chucked in the tailstock, and pre-positioned inside the work with its tip right up to the parting off position.<br />
<br />
==== Using the Steady Rests ====<br />
For the fixed steady rest, see Blondihacks' Lathe Skills #26 - How To Use a Steady Rest! [[#Youtube_Playlists_&_Videos|{below}]]<br />
<br />
Ours doesn't have ball bearing fingers, so a smooth surface on the work and adequate lubrication are essential. The thumbscrews can only tighten the fingers, so for small adjustments outwards you need to either slack off the clamping nuts or ease them slightly and use a drift against the back of the finger's slot. Once set, check the chuck still turns freely.<br />
<br />
The traveling steady rest needs to run on a machined surface, so at least for the first pass, must follow the tool, so its difficult to avoid using more compound slide overhang than is desirable. An initial surface should be cut next to the chuck or tailstock center before fitting the steady rest.<br />
<br />
Both are a PITA to fit - the fixed one has to have its clamping post inserted up through the bed, and the supplied spanner is useless near the headstock, and the travelling one's mounting holes on the saddle almost invariably need swarf picked out of them.<br />
<br />
==== Turning Between Centers ====<br />
<s>Using a MT3 to MT2 reducing sleeve, the MT2 dead center can be fitted in the spindle.</s> ''Currently the MT3 spindle taper is compromised.'' Alternatively, a soft center can be turned immediately before use in the three jaw chuck, but that must have its 60° point re-cut to concentric if the chuck is disturbed, and needs to be either large enough to bear on the chuck body, or must have a lip to bear on the end face of the jaws to take the axial thrust. Recutting the center is a PITA, as the compound angle must be set to 30° anticlockwise, then reset to a true 0° afterwards. Maybe a right-hand 30° end angle zero rake form tool is the answer, or use the carbide insert tool SSKCR0610H06 as a form tool with the toolpost rotated 15° anticlockwise.<br />
<br />
With the MT2 live center in the tailstock quill, this gives us a center either end of the work to hold it.<br />
<br />
We also need a drive dog similar to [https://littlemachineshop.com/products/product_view.php?ProductID=4473&category=1 this], and the corresponding drive post to bolt to the spindle nose. I have some 25mm bore thick wall iron pipe, which should do nicely. Lengths of the dog's straight tail and of the post TBD after I check how much the center protrudes. N.B. its recommended to tie the tail to the post to keep them in contact so they don't slam. ''Currently we will need to drive from the chuck jaws. Possibly use the exterior jaws with a short soft center gripped on the inside end and drive from the highest step.''<br />
<br />
=== Drilling ===<br />
Always start with a center drill so deflection of longer bits doesn't start the hole off-center. For larger bits (> 5 mm), first drill to the web size, then to final diameter. For a precision hole, drill slightly undersize and ream to final diameter. ''Supply your own reamers!''<br />
<br />
Caution: See note about the quill anti-rotation pin in section [[#Tailstock Quill|Tailstock Quill]] above.<br />
<br />
=== Boring ===<br />
Caution: As the spindle doesn't extend right through the headstock housing, if boring in a through hole, chips tend to fall out the back and tumble in the spindle bore till they fall into the change gears. To avoid this, one should plug the spindle bore with a wad of paper towel or rag and when cleaning up afterwards, use a rod to push it through towards the tailstock, with the chuck jaws (if fitted) wound clear of the spindle bore.<br />
<br />
A swivel bladed hole deburring tool (pale blue handle) can be found in the main room on the windowsill behind the drill press.<br />
<br />
A couple of boring jobs have been bodged with an awkwardly angled turning tool and achieving acceptable effective rake with enough clearance to reach deep enough into the hole has been problematic. I reviewed the tools we had and found none suitable for starting out in a 13mm bore, the max diameter we can (easily) drill. I therefore decided to buy a set of boring bars and make a holder for them. I had difficulty finding anything affordable under 10mm shank - the best low cost option was a [https://www.amazon.co.uk/dp/B07P5LGVBX set of nine 3/8" (9.525 mm) shank brazed carbide tipped boring bars], which would be close to the max capacity of the quick change boring bar holder - if we had one! Unfortunately this holder for our specific toolpost is difficult to find except in a toolpost bundle. Another annoyance is the variable tip height of the set, varying from 1.8 mm to 2.8 mm above the center of the shank.<br />
<br />
I therefore decided to make a boring bar holder of the [https://littlemachineshop.com/products/product_view.php?ProductID=1700 Littlemachineshop.com (USA) style] for use in the four way toolpost, as the additional rigidity will certainly help. Starting with a slightly over 50 mm length of 16 mm aluminium square bar and using the four jaw chuck , both ends were faced and an attempt was made to find its center and center drill it. It was then drilled out to ~9.8 mm after much drama due to blunt drills and drills that cut ~1mm oversize. Too big, but beggars cant be choosers as we didn't have a boring bar holder or a 3/8" reamer. Unfortunately the final hole ended up significantly off center. It was then chucked crossways and ~1 mm skimmed off its thickest side to gain clearance to allow it to be shimmed to height, then one side was slit lengthwise manually with a hacksaw.<br />
<br />
It was fitted to the for way toolpost and loaded with a booring bar, which clamped firmly. A 0.86 mm shim stack brought the tip of the largest boring bar almost spot on center height, with the difference easily accommodated by twisting the tool slightly. The three jaw chuck was then remounted, and a piece of iron pipe chucked for a test. It cuts well and leaves a decent surface finish.<br />
<br />
''The boring bar setup is a work in progress - talk to me before attempting to use them if you have a project that would benefit from boring..''<br />
<br />
ToDo: get something that can sharpen tools tipped with this grade of carbide - it needs some sort of diamond (or possibly CBN) wheel as green grit silicon carbide does little more than polish it. ''N.B. diamond wheels are rapidly eroded by grinding steel, so the supporting steel seat must be undercut with a regular grinding wheel before the diamond wheel can contact it.'' <br />
<br />
We'll also need 50 mm square sheet shims to fit under the toolpost to gain clearance in the toolpost above the tool or toolholder. A 2.4 mm shim would give us about the same above and below spindle center height, and we probably need a small selection of thinner ones.<br />
<br />
=== Thread Cutting ===<br />
The objective is to cut a thread that complies with the ISO metric thread profile. Our lathe is not currently equipped to cut non-metric threads, (with the exception of BA which have pitches based on metric threads of that era).<br />
<br />
[[File:ISO and UTS Thread Dimensions.svg|frame|center|Metric Thread Profile - from the geometry, H is ~86.6% of P]]<br />
<br />
Metric thread data - See 'Preferred Sizes' at: https://en.wikipedia.org/wiki/ISO_metric_screw_thread<br />
<br />
See "Mini Lathe User’s Guide" section '''Threading''' for general techniques *ONLY*, and above for change gears and threading dial setup.<br />
<br />
Amadeal specify the max. thread pitch as 2.5 mm. Any thread pitch greater than 1.5 nn requires the change gears to gear up. When gearing up it is desirable to distribute the ratio as evenly as possible over the two pairs of gears in the geartrain to avoid excessive tooth loading.<br />
<br />
==== External Threading ====<br />
Initially turn work to required Major Diameter, set up change gears and threading tool, touch off on the work, zero the top and cross slide dials, and do a 'scratch' pass to check the pitch. Back off the tool, return the carriage, and re-engage the half nuts on a valid dial line clear of the end of the thread then immediately stop the lathe, and hand turn the chuck till the tool tip is (hopefully) over the scratch to check the thread pickup. If all is good, return the carriage again, restart the lathe and start cutting your thread. <br />
<br />
Methods of doing so vary depending on the size of the thread and toughness of the metal, but straight-in plunge cutting is generally to be avoided as has the highest cutting forces, and does not reliably keep the carriage (and top-slide if set parallel to the work) loaded to avoid pitch errors due to backlash. <br />
<br />
If leaving the half-nuts engaged and reversing the lathe to return to the start of the thread for the next pass, its absolutely essential to back the tool out of the thread for the return pass as it will not follow the path of the cutting pass due to backlash in the geartrain, leadscrew mounts and half-nuts.<br />
<br />
==== Internal Threading ====<br />
''<nothing here yet>''<br />
<br />
== Cutting fluids ==<br />
=== Why bother? ===<br />
[https://youtu.be/mRuSYQ5Npek Watch this video] and contemplate what's actually happening to that thin ribbon of metal being removed. Most of the lathe's motor power is being turned into heat by internal friction in the chip being removed in the zone around the cutting edge, and surface friction at, and immediately behind the cutting edge, near-instantly heating the chip by up to several hundred degrees. Reducing the surface friction using a suitable cutting oil reduces the strain on the machine as a whole, and reduces workpiece and tool heating (and thus expansion) with consequent improvements in maximum usable feed and depth of cut, surface finish and accuracy. It also drastically increases the life of the cutting edge.<br />
<br />
=== Practicalities === <br />
We don't have a coolant system for the lathe and *really* don't want the maintenance hassles of using soluble cutting oil/coolant as if used infrequently its a PITA to keep recirculated high water content cutting fluids from going rancid and stinky, and they can also rust the ways, so even a total loss gravity feed system is problematic. Therefore if dry machining doesn't give a good enough finish, we tend to use oil applied topically, by hand to the work. <br />
<br />
* Hard brass is typically free-turning without oil, however some light oil for the final cut can improve surface finish, but with the disadvantage that it will increase loose chip buildup on the tool as hard brass typically forms short spalls or splinters rather than curly chips.<br />
<br />
* Many Aluminium alloys tend to be gummy, and Paraffin or other mineral spirits mixed with a little oil can help prevent the aluminum welding to the tool edge. WD40 will do at a pinch, but its messy to apply from a spray can.<br />
<br />
* Steel really needs *GOOD* cutting oil. Lard oil is the traditional choice for steel. If there are any objections to lard oil, we should bite the bullet and get some commercial dark high Sulphur cutting oil, but beware, many such oils use an additive package that includes lard oil.<br />
* Cast iron (except ductile) should be cut dry, as the carbon micro-inclusions self-lubricate it, and the carbide in the dust (primarily Cementite) are very abrasive, so tend to form a grinding compound if mixed with oil. <br />
<br />
I've sorted out an oil pot lid with a 1/2" brass collar soldered in to give a nice smooth sided hole, for ease of use and to minimize the risk of spills when using a brush to apply cutting oils, and got some dirt-cheap brushes. It fits Shippam's paste (and similar own-brand spread) jars and I've found several jars and ordinary lids to seal them for storage. Unfortunately it isn't the easiest to get this type of jars' lids back on square so they seal properly, and if you over-tighten them and there's a temperature change, they can be a total <expletive> to reopen. Using the rubberised handles of a large pair of pliers to grip the jar lid just above its rim is the best option, and avoids damaging the lids.<br />
<br />
''N.B. For the smaller brushes, the glue holding the bristles in is attacked by paraffin. To prevent loss of bristles, crimp the aluminium ferrule of each new brush of this type before use.''<br />
<br />
We have, in labelled jars:<br />
<br />
* Sulphurised Lard oil thinned with paraffin. Best choice for heavy cuts and threading in steel but stinky.<br />
* Lard oil thinned with paraffin. Good for steel and acceptable for softer copper alloys<br />
* Paraffin with a trace of light oil. Good for aluminium, and can help prevent squealing chatter on finish cuts in brass.<br />
<br />
I've also got some paraffin wax (in the form of a stubby candle), which can be applied lightly (under power) to brass and aluminium stock especially on the finish pass. It makes less mess than oil but unfortunately tends to build up on the tool tip, making it difficult to 'work by eye' without frequent pauses to clean the tool tip.<br />
<br />
We've also got a tin of [https://www.rocol.com/products/rtd-compound Rocol RTD cutting compound], which is a thick paste. Its highly recommended for drilling and tapping steel (in the drill press or by hand), but as a paste, is less useful for general lathe work unless thinned to a fluid consistency, e.g. with paraffin or white spirits. OTOH its certainly worth trying for high speed facing steel as it is less likely to get flung off.<br />
<br />
== Cleaning and Maintenance ==<br />
Swarf is a significant cut hazard to the operator, especially stringy swarf from cutting steel. Never touch it bare-handed - always use a tool e.g. a brush, or a hook, or needle nose pliers for grabbing long swarf.<br />
<br />
* After use, brush all swarf off the toolholder, compound and cross slide etc. ways and leadscrew. Ian B has blocked off the opening at the headstock end of the rear splashguard (to try to keep swarf out of the motor), so one must sweep the swarf towards the open tailstock end and catch it in a dustpan or similar. Preferably, also thoroughly clean out the chip tray under the lathe, but at least sweep out visible swarf.<br />
* Wipe up any cutting fluid residue and re-lubricate affected sliding surfaces with way oil.<br />
* Do not solvent clean the chuck guard, as it will make the plastic brittle, or even craze it. Water with a little detergent is permissible for cleaning it, with the guard totally removed from the lathe.<br />
<br />
Before engaging the half-nuts for power feed/threading, check the leadscrew is clean! ''Best cleaned under power, with a toothbrush.'' <br />
<br />
'''Caution:''' The traverse gears behind the carriage handwheel are in an open-backed housing and tend to become packed with swarf! Swarf buildup here will result in jerky carriage movement. Clean out as much as you can with a toothbrush ...<br />
<br />
===Lack of lubrication and/or swarf or dirt build-up can be disastrous===<br />
* If using the change gears/power feed, lack of lubrication of the B-C stub shaft center pin or either leadscrew end bearing can result in seizure and immediate destruction of one or more gears in the gear train or worse. <br />
* Small pieces of swarf can get between the saddle and ways, or into the slides degrading accuracy, possibly permanently if hard swarf scores them, or jamming them. The carriage handwheel gears behind the apron are notorious for accumulating swarf, and swarf buildup on the leadscrew can prevent the half-nuts engaging properly, resulting in scrapped work, and possibly stripped half-nuts. <br />
* Metal swarf can get into the motor (''though Ian B has modified the rear chip catcher to reduce the risk)'' or into the control box via the leadscrew, and short-circuit stuff. At best it will blow the fuse and need a strip-down to clean it out, at worst it may require a replacement [https://www.amadeal.co.uk/acatalog/Speed-Control-Circuit-Board--12amp-AMA_SP_CJ18_SCB12.html#SID=12 speed controller] ''(currently £96)'' and/or [https://www.amadeal.co.uk/acatalog/550W-motor-for-CJ18A-Mini-Lathe-467.html#SID=240 motor] ''(currently £105)'' and possibly other electrical parts. We should probably fit a [https://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C3-Mini-Lathe-Spares/C3-256-Leadscrew-Grommet-Dustproof-Cover C3-256 Leadscrew Grommet] to keep swarf out of the control box, as it tends to drop onto the 'Filter' board which is mounted horizontally, below the leadscrew.<br />
* Grit from grinding, sanding etc. forms a grinding paste with the way oil, and will rapidly wear out the ways, saddle and slides. Keep grit off at all costs e.g. by covering the ways and slides during grinding/sanding operations, and if there's any chance grit has gotten where it shouldn't, clean and re-lubricate *BEFORE* moving the carriage or slides, then move the carriage and slides, wipe down where they were with a clean paper towel and check there's no remaining traces of dirt other than clean way oil on the paper towel. If it doesn't come clean when you re-lubricate and move it again, a full strip down may be required to solvent clean and relubricate the precision sliding surfaces.<br />
* Although a metalworking lathe *can* be used to turn hardwood, wood dust and small chips are extremely pernicious, as they get everywhere, even clinging to clean surfaces, are abrasive due to their silica content, and are hygroscopic, promoting rust. An even more thorough clean-up than after using abrasives is needed, immediately afterwards. Oily wood dust and fine wood chips in significant quantities are a fire hazard, even in the trash bin.<br />
<br />
===Lubrication===<br />
See section: "Lubrication" in LittleMachineShop.com "Mini Lathe User’s Guide" [[Ian_M's_Lathe_Notes#Manuals|(below)]]. As we usually only open two nights a week, in the table on page 16, Daily lubrication becomes Weekly and Weekly becomes Monthly.<br />
<br />
===General Maintenance===<br />
* The grubscrews holding the cross-slide and compound slide dials tend to loosen due to vibration and use of the dials. Keep them snugged up, but not so tight the dials cant be set without an Allen key.<br />
<br />
* The screws holding the cross-slide nut tend to work loose due to vibration. Crank the handle to and fro through the backlash and visually check there is no movement of the screw heads in their holes. If there is, see the [[#Excessive_cross-slide_backlash|notes below]].<br />
<br />
===Removing the Carriage===<br />
Its possible to remove the carriage from the bed for cleaning etc. without dismantling it. The only stop to its motion is the righthand leadscrew bearing.<br />
<br />
Start by removing the tailstock. Crank the carriage to the tailstock end then remove the leadscrew bearing (two screws and a nyloc nut on the leadscrew end). With the half-nuts open, hold the leadscrew centered in them and crank the carriage off the end of its rack, then slide it off the end of the bed.<br />
<br />
Refitting is the reverse of removal, except (if its gibs are correctly adjusted) the carriage will be very tight on the end of the bed ways so may be difficult to work onto the ways without a stack of blocks of wood or similar to support it at exactly the right height. The righthand leadscrew bearing must be refitted with the carriage as close as possible to it and the half-nuts firmly closed to support the leadscrew at the correct height to hold it in alignment while the screws are being tightened. The nyloc nut controls leadscrew end-play. Fully tighten it then back it off slightly till the leadscrew turns freely with its change gear removed.<br />
<br />
If the Apron has been off, refit it with the screws no more than lightly finger tight and only finally tighten them after checking lead screw engagement at both ends of the carriage travel and that the rack and pinion operates smoothly over the full travel.<br />
<br />
== Issues and Annoyances ==<br />
As of September 2023 - mostly resolved, apart from the spindle bearings and runout, the lathe is in better condition than it has been for a number of years.<br />
<br />
===Four Jaw Chuck has two jaws too tight===<br />
Fixed 27/10/2023: Two of the chuck jaws were tight in their slots, making precise adjustment difficult due to lack of 'feel'. Moving the jaws round the slots showed the problem mostly followed the jaw not the slot. The grooves in the opposite sides of the affected jaws that run in the chuck slots were slightly out of true, and the rails either side of the slots were slightly too thick towards the center. Due to the difficulty of seeing the high spots, after cleaning up and deburring the jaws didn't do enough to ease them, I decided to grind the top of the rails where they were binding. Several repetitions of spotting with Engineer's blue, grinding, then diamond filing the high spots has eased them enough. I cleaned everything, greased the jaw slides and screws, and refitted the studs so the chuck is now fit for service.<br />
<br />
''N.B. Don't move the jaws to a different slot - the formerly tight jaws *must* stay in the slots furthest from the makers mark.''<br />
<br />
===Excessive Runout===<br />
Mostly fixed 24/10/2022: I ground the chuck seating surface of the spindle nose (outside lip) to under half a thou runout. This also cleaned up several burrs. It would be possible to do better, but that would need good spindle bearings, and a more rigid toolpost grinder mount.<br />
<br />
Our spindle nose was damaged years ago by a person with little mechanical aptitude (who shall remain nameless) beating it up with a hammer mushrooming the spindle nose. We are getting several thousandths runout at the end of the MT3 bore, a MT3 to MT2 reducer sleeve in it runs visibly out of true, as does the spindle nose flange. When you put a chuck on it, the runout is magnified by the distance from the spindle nose. Ideally we would replace the spindle when we change the bearings but its £52 [https://www.amadeal.co.uk/acatalog/4-Spindle-Upgrade-Real-Bull-Mini-lathe-CJ18-series-AMA_SP_CJ18_003RB.html#SID=9 from Amadeal] and money is tight. It may well require more work after the bearing upgrade. Once good bearings are in, if we can borrow a decent MT3 arbour as a reference, we should consider skimming the bore.<br />
<br />
===Spindle bearings===<br />
* The spindle bearings appear to be close to worn out. They are notably noisy when running, and there appears to be more slop in the spindle than is desirable. There is notable resonance around 600 RPM, and surface finish of end faces is often poor. We have some ideas for possible replacement/upgrade, but it requires a major teardown.<br />
<br />
: The original bearings are allegedly 6206-2RS or 6206-ZZ deep groove ball bearings - 2RS codes rubber seals both sides and ZZ codes metal shields. Although the deep groove gives reasonable ability to withstand axial loads, the bearing balls point contact means they are vulnerable to [https://en.wikipedia.org/wiki/Brinelling brinelling] due to shock loading. The jammed on three jaw chuck didn't help this, as before we skimmed the spindle nose lip, it had to be driven off using a bar through the spindle bore, shock loading the bearings every time. Also even a minor 'crash' could have brinelled them due to eccentric shock loading, and the lathe has previously been crashed badly enough to need drive gear replacement. There are also issues with the 'approved' method of spindle and bearing removal from the headstock brinelling them, even if you don't abuse the spindle nose with a hammer!<br />
<br />
: A possible replacement is 30206 tapered roller bearings. The new bearings are slightly thicker so the plastic spindle spacer (15) needs to be machined to length to get the 45 tooth spur gear that drives the change gears laterally aligned with the tumbler gears. If a temporary replacement (3D printed?) is fitted, the lathe can be run (without power feed capability) so this can be done on the lathe after fitting the new bearings. As tapered roller bearings have line contact, they are significantly more resistant to brinelling.<br />
<br />
: ''See [[Talk:Ian_M%27s_Lathe_Notes]] for notes, links etc. for this upgrade.''<br />
<br />
===Motor stuttering===<br />
* Fixed 21/09/2023: The motor was running very erratically and it was very difficult to set a speed. Several loose connections were found in the control box, mostly loose female spades to the motor controller board, but also a dry jointed braking resistor on the 'Filter' board, and an inhibit wire completely off its terminal on the forward/reverse switch, making intermittent contact. After tightening and/or remaking all affected connections, it was much improved but still not right below 300 RPM. The remaining issues were due to poor wiper contact in the speed control pot, and stripping it, cleaning the track and contact ring and re-tensioning the contacts resulted in the motor now running smoothly over the full speed range. The speed is slow to settle, and while part of that is probably the lag in the digital tach, I suspect that the KBIC motor speed controller isn't properly tuned as it was (allegedly) previously replaced.<br />
<br />
===Drive belt slipping===<br />
* Fixed 28/9/2022: During testing the motor after the above issue, it was noted that the chuck could be stalled, slipping the drive belt, with not much torque. The drive belt was determined to be loose and a bit worn, but still in acceptable condition. <br />
<br />
: Access for servicing the belt requires removing the control box ''(2 spades to ZVR switch disconnect the supply, speed sensor and motor simply unplug from the 'filter board')'', the motor cover, chuck guard switch assembly + wiring cover, the change gear 'A' (drive) shaft carrier assembly, and the tumbler gear assembly. See https://youtu.be/EkxlIz01BdA for disassembly/reassembly, though on our lathe, the speed encoder ring on the spindle prevents the belt cover from being fully removed without disturbing the spindle nuts. There is enough room to work with it loose, but still trapped by the encoder ring. Also, unlike the video, if the 'jack' screws under the headstock are correctly adjusted, and the studs aren't excessively bent, there is no need to make custom studs. <br />
<br />
: It turns out that our lathe was missing the M6 hex headed jack screws that press the motor down to resist the belt tension, and the motor had cocked out of position at a severe angle. I know Ian B had had considerable trouble adjusting it after the motor fault back in October 2022, and I believe it had been getting slowly worse ever since. The jack screws were probably mistaken for headstock fixing bolts during disassembly after the crash that resulted in the metal Hi/Lo gears being fitted, then lost. The penny washers on the studs had dished, so I turned them over and backed them up with smaller washers and switched to Nyloc nuts so they cant back off due to vibration. N.B. There is a packing washer on the motor side on one of the studs, presumably so the shaft is true to the ways. Adjusting the motor is awkward to say the least. One has to slack the stud nuts off a lot, pry under its rear end to lift it enough to be parallel to the ways, snug the stud nuts, check alignment, then set the jack screws and their lock nuts to hold it there, and finally tighten the stud nuts. <br />
<br />
: Tension: According to Sieg, it should be possible to twist the belt 90° mid span with a light finger grip. Other sources say 1/32" - 3/32" deflection mid span with light finger pressure.<br />
<br />
===Speed display blanking===<br />
* The speed display has been intermittent, blanking and flashing 8888 and 0 at certain speeds for as long as I have been using the lathe. Finally on 18/07/2022 it failed completely, with no display. I removed the display module and bench tested it - the pins are labelled 5V GND PL PE, PE is frame ground and PL is a TTL level pulse from the speed sensor - confirming that it was in good working order. My suspicions then turned to its power supply on the 'Filter' board. With both the sensor and display unplugged, the 5V rail was found to have a only a couple of volts, but the unreg DC was 17V and stable. Replacing the 78L05 5V regulator restored the 5V rail and normal operation.<br />
<br />
: ''I conclude its been failing for a while with high load current due to speeds with more lit segments causing it to drop out, resetting the speed display, causing it to blank, lowering the current enough for the regulator to recover, then the display MCU lamp tests (8888) then re-acquires the speed, repeating ad-nauseum till the speed is changed. I don't like the design as the high input voltage results in excessive dissipation.'' <br />
<br />
: ''ToDo: If it fails again, bench test display to measure its worst case current consumption, then fit an appropriate dropper resistor to reduce the 78L05 dissipation.''<br />
<br />
===Quill spinning when drilling===<br />
* The quill was tending to spin while drilling because its anti-rotation pin (a M5 dog tip setscrew) was sheered. I've removed the debris, aligned the scale with the top of the tailstock and fitted a longer M5 dog-tip setscrew to replace it, with a nut to lock it at the correct height. N.B. the pin isn't that 'meaty' so if using big drills in tough metals, to prevent shearing it, it should be backed out so the quill can be turned by hand and unwanted rotation controlled by being quick with the quill lock if it starts to spin, or even using a close fitting rod in one of the chuck key holes with plastic tube over it to protect the ways. <br />
: ''If the screw sheers again, the quill will need to be removed and the tailstock taken off the lathe so the sheered tip can be shaken out, and if the setscrew is difficult to remove it probably means the threads are mangled where it sheered. Try driving it right through with the quill out.''<br />
<br />
===Sloppy quick change toolpost locking mechanism===<br />
* Once the dovetail clamp screw was slackened, there was nothing preventing the dovetail twisting or cocking significantly, and friction with the toolholder made it tend to do so, making toolholder insertion and removal more difficult unless the clamping screw was backed off excessively. I added a compression spring around the clamp screw inside the toolpost to push the dovetail outwards so it mostly retains alignment when open, allowing toolholders to slide on or off cleanly with far less screw slackening.<br />
<br />
===Leadscrew rubbing===<br />
* The leadscrew shaft is rubbing on the insulating separator inside the control box. Unfortunately the corner of the relay on the Filter Control Board (#160) doesn't allow enough clearance. Although the friction isn't much of a problem at high reduction ratios, e.g. 16:1 power feed, it increases the stress on the change gear train, and may be problematic when threading at feeds above 1:1. ''Possibly pack out the control box mountings by a couple of mm.'' <br />
<br />
===High/Low lever backwards!===<br />
* The high-low drive gear selector behind the headstock is incorrectly labelled and differs from the manual: low gear (which we normally use) is with the lever towards the tailstock. ''I suspect that the gears in the headstock were refitted the wrong way round when it was upgraded to metal gears.''<br />
<br />
: ''ToDo: Get it reassembled the right way round during the spindle bearing upgrade!''<br />
<br />
===Carriage lock fouls top slide===<br />
* The T handscrew has been replaced with a M5 hex headed bolt, to permit access when the top slide is over it. An 1/4" drive 8mm socket is usually left on it, but needs to be removed when the full cross slide travel is needed. The small (4 jaw) chuck key is near enough 1/4" to use for it. If you need to (un)lock it while the compound is over it, you'll need an 8mm spanner. ''The [https://www.amadeal.co.uk/acatalog/Mini-Lathe-Carriage-Lock-463.html Amadeal lock screw] is in the spares tin as it was too high and fouled the compound slide.''<br />
<br />
===Tailstock locking lever loose===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock - See full image for key to screws]]<br />
* Diagnosed and fixed 10/1/2023 - In the base of the upper section of the tailstock, there are two dog tip set screws that engage with locating grooves in the counter-rotating shafts carrying the eccentric locking cams. They'd backed off, probably due to vibration. They need to be tightened till they bottom out in the groove, making sure they are '''in''' the groove, backed off half a turn so the shafts can turn easily, and locked in place. There's no facility to do so, so reassemble with weak threadlocker. Unfortunately to get to them you have to remove the tailstock base slide, which is held on by the pressure of four adjusting grub screws, which all need backing off, and one socket headed bolt from underneath so full tailstock realignment is required after reassembly, which even for a rough alignment is tedious.<br />
: <s>The tailstock locking lever is loose and can be pulled out on its axis. It works OK when fully pushed home but needs investigating. ''I tightened the grub screw as the lever was coming off its shaft, but the whole shaft pushes/pulls in and out. It works OK fully pushed in, but it seems something that is meant to retain it has failed inside the tailstock base.</s><br />
<br />
===Gear alignment issues===<br />
* Change gear alignment is poor. I've currently got a gapped washer (to clear the key) packing out the A shaft so the gears line up, but this reduces the key's engagement so is problematic due to the high loading if the gears are set up for coarser threads. <s>Also I need to turn down some penny washers to slightly less than the root diameter of the metal 20T pinions, as gear retaining washers.</s> ''The gear retaining washers for A gear and B-C stub shaft are now done, turned down to slightly under 16 mm dia. Spares in the change gear tin. ToDo: The D (leadscrew) washer requires a larger center hole, so make two more with that hole.'' <br />
<br />
===Saddle gibs loose===<br />
* Fixed 11/04/2023: I took the apron off for access (and to clean the carriage handwheel gears), and found the front sheer plate screws were completely loose. I've snugged them up some and set the opposing grub screws and got a lot of the slop out. I've re-checked the front ones, and taken up the slop in the rear ones - Unfortunately it wasn't possible to get carriage movement to have an even 'feel' over its whole travel, and its noticeably tighter near the tailstock. If light hand pressure on the side of the unlocked carriage can cause movement (with the half-nuts open), its time to readjust them again, though it should be possible to move the carriage with a firm push. <s>The saddle gibs (actually the sheer plates) were too loose, to the point that engaging a slightly stiff threading dial could cause it to self-feed, an obvious crash hazard if working near the chuck or a step in the work.</s><br />
<br />
''N.B. the lefthand front opposing grubscrew is short, (fully recessed) and unlike the others does *NOT* have a locking nut as it must clear the traverse pinion. A wrap of PTFE tape provides enough friction to keep it in place, though possibly a bit of nylon fishing line down its hole would be better.''<br />
<br />
===Excessive cross-slide backlash===<br />
* ''Fixed 21/11/2023.'' Originally, back in October 2023, The cross-slide screw had excessive backlash (nearly three turns), which increases the risk of loosing track of the cut depth when cutting steps, and during threading operations. If you ended up off by a turn too far in, a crash would be the most likely outcome.<br />
: The original excessive backlash was traced to loose cross-slide screw nut mountings. The nut has two socket headed cap screws pulling up, one either end, accessible from the top of the cross-slide, which control the tilt of the nut to take up backlash in the nut, and an opposing grub screw pressing down on the center of the nut to make it longitudinally rigid. Snugging up the grub screw reduced the backlash to 10 divisions or so, or 0.25 mm. A year later, the backlash had increased to one turn due to the cross-slide nut mounting screws working loose again.<br />
<br />
: 07/11/2023: I investigated further: It is difficult to get the cross-slide nut aligned correctly as it must be at the same height as the screw which is constrained by the bearing surfaces in the bracket. With the cross-slide almost at the front limit of its travel, I removed the screw and set the nut as level as possible and visually centered in the bore, then re-fitted the bracket and screw, then adjusted the tilt till it turned freely through the backlash. I then tilted it up at the front till some drag was felt to minimise the backlash and tightened the screws to lock it in place balancing them to maintain the same feel as I tightened them. The result was 7 divisions of backlash, acceptable but not great. During normal turning operations, the load on the nut is tension on the front screw and pressure on the grubscrew, so if it slackens again due to vibration from chatter, odds are it will be the rear screw that's loosened.<br />
<br />
: 16/11/2023 - 21/11/2023: The backlash had crept back up to 11 divisions (0.275 mm). We don't have any >14 mm brass stock (or even near that) so I tried making the shim washer out of aluminium. I was shooting for 0.24 mm but due to poor technique got 0.28 mm. No good - locked solid. I lapped it down and tried it till I got it down to 0.20 mm which gave about 3 divisions backlash - good enough, but the screw was too tight due to the shim washer not being bevelled at its outer edge resulting in it cupping in its seat. Filing a bevel round the OD and re-lapping it resulted in a 3 - 4 divisions of backlash. Its a little mushy due to the washer having been kinked removing it, so ideally a new (brass) washer should be made. <br />
<br />
* Further reduction of backlash: https://youtu.be/Wu_tI29JL2Y?t=163 <br />
: Brass tinned with Pb-free solder to form a white metal bearing surface should work at least as well as the bronze used in the video. The shim washer needs to be 10.2mm ID, with a full thickness bevel on a 14 mm OD. It isn't necessary to remove the lead screw from the cross slide, as the washer can be fitted in-situ with only the bracket removed.<br />
<br />
===3 Jaw chuck didn't mount properly===<br />
* Fixed 7/4/2023 by grinding the spindle nose lip. The three jaw chuck can now be installed and removed by hand with no hammering. A test bar in it now has only 2 thou runout (TIR) at the chuck.<br />
: <s>The three jaw chuck and the faceplate aren't seating properly on the spindle nose. Its too tight on the register diameter of the lip. This results in grossly excessive runout, and also makes this chuck and the faceplate a PITA to fit or remove.</s><br />
: ''The spindle nose had been abused with a hammer (before my time) which mushroomed it and may have brinelled its bearings. See '''Excessive Runout''' and '''Spindle bearings''' above.''<br />
<br />
== Manuals, Books and other resources ==<br />
=== Manuals ===<br />
The [https://wiki.richmondmakerlabs.uk/images/a/a3/Lathe_InductionNotes.pdf RML CJ18A Mini-Lathe Induction Notes]. Your mandatory Lathe Induction will cover most of this but its good to be able to refer back to it.<br />
<br />
Official [https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Amadeal CJ18A Manual], or paper copy (less complete) kept on shelf above lathe.<br />
<br />
The [https://www.chesterhobbystore.com/wp-content/uploads/2022/11/Conquest-Super-Lathe.pdf Conquest Super Lathe manual] is considerably better than the Amadeal manual and is for a near-identical machine.<br />
<br />
The [https://littlemachineshop.com/images/gallery/info/minilatheusersguide.pdf Mini Lathe User’s Guide] from LittleMachineShop.com is even more comprehensive, going into its usage in some detail, with a proper TOC, and covers both US and Metric versions of Realbull Mini-lathes. ''The only fly in the ointment is the threading section assumes a US lead screw so change gear selections and threading dial divisions will not be correct for our lathe.''<br />
<br />
[https://www.arceurotrade.co.uk/machineguides/C3-Mini-Lathe-Dismantling-and-Reassembly-Guide.pdf Sieg C3 Mini-lathe Dismantling and Reassembly Guide] "A picture story book to help you dismantle and reassemble your Sieg C3 Mini-Lathe" ''It is similar enough to ours to serve as a maintenance guide, except for the electronics, spindle drive and other headstock innards.<br />
<br />
The motor controller is a clone of a [https://acim.nidec.com/drives/kbelectronics/-/media/kbelectronics/documents/dc-drives/manuals/kbic_manual.ashx?la=en KBIC® SCR DC Motor Speed Control]<br />
<br />
=== Books ===<br />
'''Metal Turning on the Lathe''', by David A Clark, Crowood Metalworking Guides, ISBN-13: 978-1847975232 [https://www.amazon.co.uk/gp/product/B00E78RKIG Kindle Edition (£8.99)]. ''A 'free' epub can be googled for, *NOT* linked here due to dubious legality.''<br />
<br />
'''[https://archive.org/details/03screwcuttinginthelathe Screwcutting In The Lathe]''', by Martin Cleeve (a pen-name of Kenneth C Hart), Workshop Practice series #3, ISBN-13: 9780852428382<br />
<br />
'''[https://archive.org/details/15workholdinginthelathe Workholding in the Lathe]''', by 'Tubal Cain' (a pen-name of Tom Walsh), Workshop Practice series #15, Argus Books, ISBN-10: 0852429088<br />
<br />
'''[https://archive.org/details/20metalworkandmachininghintsandtips Metalwork and Machining Hints and Tips]''', by Ian Bradley, Workshop Practice series #20, ISBN-13: 9780852429471<br />
<br />
'''[https://archive.org/details/38toolandcuttersharpening Tool and Cutter Sharpening]''', by Harold Hall, Workshop Practice series #38, ISBN-13: 9781854862419<br />
<br />
'''[https://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpaperT204.pdf Cutting Fluids]''', by EC Bingham, NIST Tech. Paper No. 204, 1921<br />
<br />
=== WWW resources ===<br />
==== Mini-lathe Specific ====<br />
There's a *LOT* of mini-lathe info online. Notable sites include:<br />
* http://www.mini-lathe.com/ - A major Realbull/Sieg mini-lathe resource.<br />
* http://mikesworkshop.weebly.com/lathe-modifications.html - many mods including carriage DRO autostop, and variable speed leadscrew motor drive, cross-slide motor drive, etc. He also has a page with a bunch of accessories, toolholders etc. - http://mikesworkshop.weebly.com/lathe-accessories-and-tooling.html<br />
* http://andysmachines.weebly.com/variable-speed-controls.html - Scroll down to the 'UPDATE' section for the schematic of a very similar SCR speed control board. It also has the schematic for an earlier version of the Auxiliary Control Board (aka: 'Filter' board).<br />
<br />
==== Forums ====<br />
''with publicly accessible archives''<br />
* https://groups.io/g/7x12MiniLathe - Mini-lathe specific, active<br />
* https://www.hobby-machinist.com/forums/mini-lathe-mini-mill-information.220/ - active<br />
==== Youtube Playlists & Videos ====<br />
* Blondihacks: [https://www.youtube.com/playlist?list=PLY67-4BrEae9Ad91LPRIhcLJM9fO-HJyN Lathe Skills] (playlist) - "This is an educational series to help you learn to use your metal lathe. Watch them in order for best results! Satisfaction not guaranteed, especially if you're a cranky sort of person."<br />
* Frank Hoose (Minilathe.com) has a couple of relevant Youtube playlists:<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn7ON0jGM5UbM-KZDT56MOIp Mini Lathe Operations]<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn4nGRZaVq3wTOlvZNOmdAZ2 Mini Lathe Overview]<br />
<br />
==== General Machining ====<br />
* https://www.machiningdoctor.com/ - "THE #1 MACHINING TECHNICAL HUB"<br />
<br />
==Projects==<br />
[[File:VESA mount.jpg|thumb|Machined VESA mounting plate (left) and plate from Dell monitor stand it must match (right). The translucent washer shows the size of the original center hole.]]<br />
* My first faceplate project was boring out the center hole in a VESA mounting plate to adapt it to fit onto a surplus Dell 1708FP monitor stand. The part was centered using the tailstock dead center engaging with its original center hole. I clamped the part with studs and penny washers on the driving side of two opposite corners, with cap screws in the next slot round to trap the corners under the clamping washers, then withdrew the tailstock and dead center. After machining out the bore, I used the tip of the tool, rotating the chuck by hand, to scribe a circle for laying out the bolt holes. I finished off laying out and drilling the bolt and locating holes by hand at home, fitted it to the stand, and mounted the 2nd hand LG 24" widescreen monitor.<br />
<br />
* Another ultimately unsuccessful project was fly cutting aluminum flat bar to thickness to make custom shims for the set of carbide insert tools, for the four way toolpost. The 8 mm shank tools need ~2.5 mm shim stacks, and the 6 mm shank tools need ~4.5 mm shim stacks. Ideally I'd machine single shims, but the only stock I've got handy cleans up to only 3.2mm, and some fine shimming may be needed to fine-tune the tool height.<br />
<br />
: After sorting out the clamps so they were no longer twisting the aluminum flat bar stock, and switching to the short 45° turning SCMT06204 insert tool in the four way toolpost, to improve rigidity and get a well controlled tip radius, the finish was much improved. I'm still having problems getting an even thickness and am getting approx. 0.05mm variation, I suspect due to the aluminium bar stock distorting due to internal stresses as its surface is cut away. ''ToDo: try supergluing the stock to the faceplate before clamping to further reduce chatter and stop the warping.''<br />
: Looking back on this project a year later, its fairly obvious that the thickness variation was probably due to faceplate surface runout due to the damaged spindle nose.<br />
<br />
* Raphael has been working on a steel rocket nozzle with some assistance from myself. We have set up the rough cut chunk of ~ 50mm steel bar, faced both ends (to 50mm length) and turned the OD to 49mm to clean it up. Its going to need through drilling, probably some boring, and quite a bit of detail work on the OD. It will then need to be transferred to a jig in the drill press vice to allow a pattern of angled traverse holes to be drilled with acceptable accuracy.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Blog_2024&diff=17603Blog 20242024-01-01T09:07:42Z<p>IanM: Created page with "== What we have been doing at Little House == Previous years blogs are available from the Main Page"</p>
<hr />
<div>== What we have been doing at Little House ==<br />
<br />
Previous years blogs are available from the [[Main_Page| Main Page]]</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_Lathe_Notes&diff=17601Ian M's Lathe Notes2023-12-15T11:43:33Z<p>IanM: /* Chucks and Chuck Jaws */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br />
<br />
''Currently these notes are semi-organized and non-authoritative. As I become more experienced with the RML CJ18A mini-lathe, I'm cleaning up, extending and reorganising them. Some lathe operating experience is assumed. If in doubt, '''*ASK*''' me, Andy H<sup>*</sup> , Jonathan H or another experienced minilathe operator!<br />
<br />
''* Andy H should be asked (for an authoritative answer) any questions involving RML usage policies or acquiring tooling or materials through RML.''<br />
<br />
== The Lathe ==<br />
Our Facilities page [[Facilities#Lathe|has]]:<br />
<blockquote><br />
'''Lathe'''<br />
[[File: Lathe2.jpg |200px|right | Lathe]]<br />
In the kitchen. <br />
<br />
Marked as a CJ18A Mini-Lathe from [[https://www.amadeal.co.uk/acatalog/CJ18A-Mini-Lathe-7x14-Machine-100mm-3jaw-Metric-With-Metal-Gears-AMA_LA_CJ18_M_3_MGRB.html Amadeal]]<br />
[[https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Manual]] <br />
<br />
[[Media:Lathe InductionNotes.pdf| Induction Document]]<br />
<br />
Possible upgrades:<br />
*https://www.youtube.com/watch?v=GwT-JQLbNPA<br />
<br />
''Please do not use the lathe until you have received induction'' <br />
<br clear=all><br />
</blockquote><br />
Its a Chinese import 7x14 mini-lathe. The 7x14 refers to the maximum diameter and length of work, in inches and is only a theoretical measure of the working envelope as you loose length to the chuck + any tailstock tooling, and the diameter is over the bed, not the cross-slide. See actual specifications below. <br />
<br />
Most if not all Chinese 7x10 to 7x16 mini-lathes seem to be remarkably similar (not uncommon with Chinese products due to [https://www.bunniestudios.com/blog/?p=284 Shanzhai (山寨)] )<br />
and the OEM of our Amadeal CJ18A Mini-Lathe was probably [https://www.made-in-china.com/showroom/cheap-lathe Yangzhou Realbull Machinery Co. Ltd]. Very similar lathes are also made by [https://www.siegind.com/lathe-machine.html Sieg], but their lathes tend to be slightly less sophisticated than the equivalent Realbull models.<br />
<br />
''N.B. Many Sieg parts are known to have slight but critical differences from Realbull parts, so '''DON'T''' order Sieg spares for a Realbull lathe!<br />
<br />
== Key Specifications ==<br />
Amadeal says the CJ18A Mini-Lathe is a 7x14 model with:<br />
<blockquote><br />
* Power 550 W<br />
* Distance between centres : 350 mm<br />
* Swing Over Bed: 180 mm<br />
* Swing Over Cross Slide: 110 mm<br />
* Taper: MT3<br />
* Tailstock Taper: MT2<br />
* Chuck diameter: 100 mm<br />
* Spindle Speed: 50 - 2500 rpm ''(with digital readout)''<br />
* Spindle Bore: 20 mm<br />
* Cross slide Travel: 65 mm<br />
* Range of Metric Threads: 0.5 - 2.5mm.<br />
</blockquote><br />
* The lead screw is metric, pitch 1.5 mm.<br />
* The spindle center is 90.6 mm above the flat of the bed (measured).<br />
<br />
Even though the compound and cross slide handwheels appear to be calibrated in thousandths of an inch, as ours is a metric machine, they only approximate that. One turn of a slide handwheel is 1mm advance, and they have 40 divisions, so each division is 0.025 mm, (approx. 0.984 [https://en.wikipedia.org/wiki/Thousandth_of_an_inch thou]). Similarly, the tailstock quill advances 1.25 mm per handwheel turn, which has 50 division dial, giving the same 0.025 mm divisions, but only 4 turns per 5 mm. The carriage handwheel is awkward - it moves approx. 19.2 mm per turn, and doesn't have a dial scale.<br />
<br />
== Notable Accessories ==<br />
We have:<br />
* [https://www.amadeal.co.uk/acatalog/160mm-Face-Plate-for-the-4-Mini-lathe-AMA_AC_CJ18A_FP160RB.html#SID=129 160 mm (6 1/4") Faceplate]<br />
* 100 mm (4") three jaw self-centering chuck (OEM standard) 22.5mm bore, with inside and outside jaw sets<br />
* 100 mm (4") four jaw (independent) chuck with reversible jaws (8 TPI screws)<br />
* Tailstock drill chuck (max. 13 mm dia.)<br />
* Live center for tailstock (+ OEM fixed center) <br />
* Four way Tool Post (OEM Standard)<br />
* [https://www.amadeal.co.uk/acatalog/Quick_Change_Tool_Post_for_the_mini-lathe.html Quick Change Tool Post] + 3 tool holders<br />
* [https://www.amadeal.co.uk/acatalog/Fixed-Steady-for-Mini-Lathes-AMA_AC_CJ18A_FSRB.html#SID=145 Fixed Steady Rest]<br />
* [https://www.amadeal.co.uk/acatalog/Travelling-Rest-for-Mini-Lathes-AMA_AC_CJ18_TSRB.html#SID=144 Travelling Steady Rest]<br />
<br />
''You'll find all of the above on the shelf above the lathe, with the accessories in the wooden box, apart from the steadies, which live next to it. Change gears, spare parts, and most cutting tool tips/blanks are in labelled white rectangular tins behind the lathe.''<br />
=== Measuring Tools ===<br />
We have:<br />
* Various dial indicators - the one with the adjustable magnetic base stand is the most convenient for most lathe setup work.<br />
* 25mm micrometer (in little grey case)<br />
* Grey case containing set of measurement tools including dial calipers, micrometer, steel rule (metric & inch), engineers square, and a fish-tail gauge<br />
<br />
''We currently lack''<br />
* ''A tool height setting gauge''<br />
<br />
=== Hand Tools ===<br />
Some common tools needed for normal use are kept with the lathe, in or attached to the wooden accessories box:<br />
* 2 mm Allen key - adjusting cross-slide and compound gibs<br />
* 4 mm Allen key - quick change toolholder tool clamping screws + height adjust, tightening dials<br />
* 5 mm Allen key - four way toolpost tool clamping screws, engaging/disengaging threading indicator<br />
* 6 mm Allen key - locking/unlocking quick change toolholder<br />
* 8 mm spanner - locking carriage when 8 mm socket can't be used, locking gib adjuster nuts <br />
* 13 mm spanner - changing chucks, locking steady rest jaws<br />
* Very long needle nose pliers - for grabbing swarf safely, holding one end of emery cloth safely so you can keep your fingers away from the jaws, and extricating small objects from awkward places.<br />
<br />
== Change Gears ==<br />
[[File:BC puller 1.jpg|thumb|Custom puller for B-C stub shaft]] [[File:BC puller 2.jpg|thumb|Pulling the B-C stub shaft]]<br />
See "Conquest Super Lathe" manual ([[#Manuals|below]]), section '''4.7 Change Gears''', PDF pages 28-29, but see below for mesh adjustment. The LittleMachineShop.com "Mini Lathe User’s Guide" (also below) section '''Threading''' gives a far better explanation, with pictures and diagrams, but its for a lathe with a US 1/16 inch pitch leadscrew, not a metric 1.5 mm pitch one like ours, so you *MUST* ignore all the tables in that section, replacing them with metric mini-lathe (with 1.5 mm pitch leadscrew) equivalents. <br />
<br />
We have the following tooth count gears: 20,20, 30, 35, 40,40, 45, 50,50, 60,60, 80,80<br />
which consist of the OEM power feed gears + the metric change gear set. Apart from the metal 20 tooth pinions, they are all plastic, probably Delrin if the molded in 'POM' marking can be trusted, but possibly plain Nylon 6, and are metric Module 1.<br />
<br />
If we wanted to add the capability to cut US/Imperial threads we'd need to buy additional 55, 57 and 65 tooth gears, and possibly a 21 tooth metal pinion.<br />
<br />
CGTK's [https://www.cgtk.co.uk/metalwork/calculators/changegears/minilathe?gears1=20,20,30,35,40,40,45&gears2=50,50,60,60,80,80&gears3= Change Gear Calculator] ''(link preloaded with our gear list)'' is useful if you don't want to calculate the ratios from first principles. Not all suggested combos will physically fit.<br />
<br />
* Take care *NOT* to loose the keys in the A and D shaft keyways - turn each shaft till the keyway is up before removing the gear. <br />
* The B and C gears are coupled by a hollow stub shaft (with an integral key), which is so tight in the gears it has to be pressed or driven out - I've made a puller just for this task, kept in the change gears tin.<br />
* The center of the B-C stub shaft *MUST* be lubricated where it runs on its pin on the change gear banjo bracket, with grease or heavy oil. ''Seizure of the stub shaft due to running dry is a frequent cause of catastrophic mini-lathe geartrain failures!''<br />
* Don't get oil on the change gears as it can cause plastic gears to crack. Only PTFE drylube or plastic compatible white grease should be used on their teeth. <br />
* Adjust the B-C pin position in the straight slot first to set the C to D gear mesh, tighten its nut, then swing the whole banjo about the D shaft boss to set the A to B mesh, and finally tighten the banjo clamping nut.<br />
* Check both gear meshes have running clearance by turning the chuck by hand enough to complete one full turn of the leadscrew, and by attempting to turn the intermediate gear(s) to assess backlash, If excessive resistance is felt or if there's significant backlash, readjust the gears. If you have difficulty judging the mesh, a strip of 80 gsm copier paper (approx. 0.1 mm thick) wound into the meshing teeth before tightening the stud or banjo will give appropriate clearance once removed. Once setup, check the gears run quietly under power.<br />
* If the sum of the tooth counts C+D is the same as for the ones you just removed and they were correctly meshed, you don't need to move the stub shaft pin. If A+B is <u>also</u> the same, you don't need to move the banjo. e.g. If it was set up for 16:1 reduction power feed, 1 mm (40:60 - 50:50) for M6 and 1.5 mm (e.g. 40:60:40) for M10 pitches can thus be achieved by only swapping gears. <br />
<br />
''The change gears, puller, etc. and a box spanner for the banjo nut are kept in a white rectangular tin behind the lathe.''<br />
<br />
=== Power Feed ===<br />
When used for turning with power feed, the change gears should be set for a 16:1 reduction (A:20 : B:80 - C:20 : D:80) using the pair of small metal 20 tooth pinions and the 80 tooth plastic gears (largest in set), for a feed of 0.09375 mm per turn (1.5 mm/16). Unless continuing your threading project the next session, please re-fit the 16:1 power feed set after threading so the power feed is ready for use. <br />
<br />
* *ALWAYS* leave the feed direction selector lever in its neutral (no feed) position, and the half-nuts open after use.<br />
* *ALWAYS* check the carriage lock is disengaged before engaging power feed. Unlock the carriage after use. <br />
<br />
=== Threading Dial ===<br />
The threading dial is an aid to re-engaging the half-nuts at the right moment so the tool will retrace its previous path cutting deeper, rather than offsetting axially some fraction of the thread pitch and ruining your work. Its based on the concept of the lowest integer multiples of the leadscrew and thread ''(being cut)'' pitches that exactly match, but for mechanical simplicity it only covers certain selected multiples of the leadscrew pitch.<br />
<br />
We have a choice of three pinion gears:<br />
{| class=wikitable<br />
|+ Threading dial Pinion Gears<br />
|-<br />
! Teeth !! Colour Dot !! Usable lines !! OD gear !! Dist. per turn<br />
|-<br />
| 14 || Red || 1,7 || 7.51 mm || 21 mm<br />
|-<br />
| 15 || Orange || 1,5,9 || 8.05 mm || 22.5 mm<br />
|-<br />
| 16 || Green || 1,4,7,10 || 8.37 mm || 24 mm (2 mm/div)<br />
|}<br />
They are now colour coded, with a paint dot on the gear end face ''(the only non-wear surface)''. The 16 tooth one is normally left on the lathe, but disengaged when not threading to minimise wear on the lead screw. The others are kept in the Change Gear tin.<br />
<br />
There's a threading dial 'pickup' calculator here: https://www.cgtk.co.uk/metalwork/calculators/threaddialindicator <br />
<br />
Initially select ''Lathe:'' '''Custom''', and enter the following below:<br />
* ''Units:'' '''Metric'''<br />
* ''Lead Screw Pitch (mm):'' '''1.5'''<br />
* ''Thread Dial Indicator Gear Teeth:'' '''16,15,14''' <br />
* ''Lines on Thread Dial Indicator:'' '''12''' <br />
* ''Line Marking:'' '''Every Line Numbered'''<br />
Note the teeth list is entered in reverse order so the resulting table highlights any required pinion changes.<br />
<br />
N.B. The dial is only friction clamped to the pinion by its center screw. If you have any reason to suspect it may not be properly aligned: <br />
# With the power off and the carriage unlocked, engage the feed direction lever upwards. You'll probably need to turn the chuck by hand to get it to engage.<br />
# If the threading indicator isn't already engaged, loosen the threading dial support block bolt, pivot the block to engage the pinion with the leadscrew and retighten the bolt.<br />
# Engage the half nuts, again turning the chuck by hand till they drop in. <br />
# Turn the chuck a couple of turns, top towards you to take up any backlash, then lock the carriage, taking care not to push it left while locking it.<br />
# Loosen the screw securing the dial to the pinion.<br />
# Align the '1' line of the dial with the index line, by rotating the dial clockwise, then retighten the screw.<br />
# Don't forget to disengage half-nuts and unlock the carriage!<br />
<br />
The above instructions should result in the half-nuts engaging cleanly when exactly on any valid line when threading towards the headstock. If it is required to thread away from the headstock, there will be a slight offset from the line due to backlash between the spindle gear and leadscrew, so engage slightly early.<br />
<br />
Changing the pinion:<br />
# Loosen the threading dial support block bolt and disengage from the leadscrew.<br />
# Undo dial center screw, and remove it and the dial, dropping the old pinion out the bottom.<br />
# Oil the shaft of the new pinion with a drop of light oil and insert it from below, gear end down.<br />
# Refit dial and screw.<br />
# Check the dial and pinion turn freely with minimal resistance.<br />
# Align as above.<br />
<br />
== Tailstock and Steadies ==<br />
These are mostly used to support long work ''(long with respect to its diameter)'' to improve rigidity, increasing accuracy and reducing chatter. The Tailstock quill is also used with a drill chuck for drilling.<br />
=== Tailstock ===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock base]]<br />
The tailstock can be offset to turn shallow tapers between centers. We don't currently have the accessories to turn between centers, namely <s>a MT3 dead center for the spindle, or</s> any drive dogs for the work. Also realigning the tailstock after turning a taper can be a PITA. The photo shows the tailstock adjusting screw locations ''(C - Lateral, and D - Skew)'' and the block on the baseplate they engage with. Adjustments can only take effect when the tailstock locking lever is eased to take the pressure off the baseplate. As we don't have a MT3 center, one has to turn a fresh point on a test workpiece for a rough tailstock alignment reference. Fine alignment, to avoid inadvertent taper turning, can be done by mounting a long precision ground bar between the chuck (or preferably a center in the spindle), and a dead center in the tailstock and sweeping it with a dial indicator on the carriage. Finally a test cut should be taken at either end of a bar between centers, and the diameters checked with a micrometer. Assuming the bed has previously been properly levelled and shimmed to take out twist ''(not the case at RML as we don't have it bolted down)'', any remaining difference in diameter will be double the tailstock offset, smaller at the tailstock being offset towards the front. Fine adjustment cant be achieved by jacking with the screws, its best to ease the adjusting screws, bump the tailstock into alignment then take up the screws again, checking the alignment is maintained when the tailstock is unlocked and relocked. There is no vertical adjustment, though shims can be added between the tailstock and its base.<br />
<br />
==== Tailstock Quill ====<br />
There is a metric/imperial scale on the top of the quill, read against the end of the tailstock, for depth measurement when drilling. The tailstock quill has a 1.25 mm pitch thread and a 50 division dial. Each division is therefore 0.025 mm, and it only takes 4 full turns of the handwheel to move the quill 5 mm. <br />
<br />
To eject MT2 taper tooling and centers from the tailstock, wind the quill all the way in.<br />
<br />
N.B. The quill anti-rotation pin (dog-tip setscrew + locking nut in top of tailstock near to the quill lock) is only M5. It will sheer if a large diameter drill jams in the work. Please back it out clear of its keyway if using large drills, and use alternative methods of preventing chuck rotation. To re-engage it, crank the quill out till you can see the keyway, align it with the screw and screw in the screw till it gently bottoms out, then back it off a quarter turn. Try twisting the quill to check its properly engaged, then tighten the locking nut gently to hold the screw in position clear of the bottom of the keyway.<br />
<br />
=== Steady Rests ===<br />
We have two, both with brass tips that must be kept lubricated during use.<br />
<br />
The fixed steady mounts on the ways, and is most useful when turning longer work that wont fit through the spindle bore. Adjustment is critical, and the surface the tips run on must be smooth and concentric, as any misalignment that forces the work off center will result in the work wobbling in the chuck, marring it, with a high risk of it becoming un-chucked, which can be dangerous at speed.<br />
<br />
The travelling steady mounts to the headstock side of the carriage to locally resist the deflection of thin long work, due to the cutting forces. It only has two tips, to resist climb, and deflection away from the tool, and requires readjustment after every cutting pass.<br />
<br />
== Tooling and Tool Holders ==<br />
'''Key dimensional data:'''<br />
* The quick change holders accept up to 10 mm shank tools. <br />
* The four way toolpost has 50 mm long sides, a seat width of 15 mm and can clamp tools of up to 5/8" (15.875 mm) shank ''(check this)'', but the slot base is only 10.4 mm below the spindle center so cannot be used with >10 mm shank tooling unless it has a dropped tip. Large tooling with a centered tip is also problematic as you run out of height above the shank when trying to shim to match the spindle center height. <br />
<br />
===Quick Change Toolpost===<br />
I've got the quick change toolpost and toolholders setup for mostly easy use. The three toolholders came with cantilever height setting arms which historically haven't been installed as the supplied fixing screws were too short. That's all now sorted out and a HSS RH turning tool and a HSS hand-ground grooving/parting-off tool are now mounted in two of the holders and set to height. The third is kept free for other tools. <br />
<br />
The quick change toolpost has been modified with a spring to press the dovetail clamp outwards and help stop it twisting or flopping about to ease toolholder fitting and removal. The dovetail clamp (socket headed screw on toolpost side opposite dovetail) feels a bit stiffer than before, but will take less than half a turn to go from open (with the toolholder lifting out or dropping in easily) to fully clamped. As there is so much less clearance in the open position you should no longer need to wiggle the toolholder while clamping it to get a consistent height. If the dovetail clamp ever gets misaligned, twist it straight by eye, slacken off a bit further than usual to get a toolholder on, clamp it to align the dovetail then release, reseat the toolholder and re-clamp to ensure its at its preset height. You cant adjust the height by 'jacking' with the height screw due to its offset leverage. Instead, back off the height screw and hold the toolholder at the desired height while locking the dovetail clamp, then adjust the height screw (and locking nut) to hold it there, then check it doesnt change height significantly when you unclamp and reclamp the dovetail. <br />
<br />
Unfortunately the OEM height setting screws foul the toolpost locking nut handle. Currently, if you need to swap toolposts you will have to first remove the quick-change tool holder from the post. There is enough nut handle swing to allow the quick change toolpost to be unclamped and rotated to fine set the tool angle without removing the toolholder. It also seems the mating surfaces may be slightly out of square, as if you rotate the toolpost 90° or 180°, the nut swing may be insufficient to re-clamp it without removing the toolholder to do so. Add a M10 washer under the locking nut if the handle ends up pointing in an undesirable direction! A thin M10 washer is kept with the toolpost collar for this purpose, and will shift the handle position by about a third of a turn. <br />
<br />
''ToDo: Make a taller nut of a similar pattern, to clear the height setting screws.''<br />
<br />
===Four Way Toolpost===<br />
The OEM four way toolpost is significantly more rigid than the quick change toolpost + holders because it has fewer and thicker parts and less overhang. Therefore the four way toolpost should be used when using carbide tooling. It requires shimming under the tool to set the tip height to the spindle center height - see below. The tool shanks are mostly significantly less than 15 mm wide, so need to be centered under its clamping screws, tempting as it is push the shank in for full side contact with the toolpost. If possible clamp the shank with all three screws not just two.<br />
<br />
==== Shimming ====<br />
We typically only mount up to two tools, and want maximum rigidity, so use 50 mm x 15 mm shims, (the full seat area), preferably with deburred edges and radiused corners so they aren't a hazard to the operator.<br />
<br />
We have pre-cut and marked shims of the following thicknesses: <br />
* 1x 3.23 mm, 2.42 mm, 1.56 mm, 0.32 mm, and 0.25 mm<br />
* 2x 1.00 mm, 0.77 mm, 0.12 mm, 0.11 mm, 0.10 mm and 0.05 mm<br />
* 4x 0.53 mm<br />
<br />
Our shims are mostly found materials (hence the awkward thicknesses) and are mostly a mixture of aluminium and steel, with a couple of GRP ones. The toolpost seat '''<u>must be absolutely clean</u>''' to avoid embedding debris in the aluminium or GRP shims, to get a consistent height and avoid tilting the tool - wipe it every time you change a tool! Put the thin shims at the bottom of the stack to avoid the tool shank edges creasing them. Shims are kept in a little yellow plastic box with a clear lid, near the carbide tools case.<br />
<br />
I made a tool height setting gauge (T shaped black acrylic with steps in its sides) which can be used to check the tool tip height matches the spindle center height using either the flat of the ways or the saddle as a reference. The tool tip should just fit under the lip of the appropriate step, with the T arms across the ways flats or on the saddle. It is kept in the box with the carbide insert tools.<br />
<br />
''ToDo:'' <br />
<br />
* ''Cut more shims neatly, mark them with their thickness.''<br />
* <s>''Do test cuts and start noting shim stack-ups for various tools.''</s><br />
* ''Organise shim storage!''<br />
<br />
=== HSS Tools ===<br />
[[File:Tool Bit Geometry.jpeg|thumb|Single point cutting tool geometry]]<br />
Our HSS tools are made from 8 mm square bar stock, hand-ground to tip profile in-house. See LittleMachineShop's [https://littlemachineshop.com/images/gallery/instructions/grindingtoolbits.pdf Grinding Tool Bits] notes. <br />
<br />
I've installed our usual HSS LH turning and parting off tools in two of the quick change holders and set the heights correctly. There are a couple of other HSS tools or tool blanks knocking about. Taking heavy cuts turning steel (even with good cutting oil) blunts HSS tools fairly quickly, which are time-consuming to re-sharpen nicely without a dedicated tool & cutter grinder with appropriate jigs. Its worth noting that the usual 'speeds & feeds' tables are commonly based on surface speeds expected to give a half hour (active cutting) tool life before resharpening.<br />
<br />
I touched up the LH turning tool by lapping on wet & dry (silicon carbide) paper on glass (Aka: [https://en.wikipedia.org/wiki/Scary_sharp 'Scary Sharp']) working upwards through the grits 200, 400, 600 and finally 1000, initially 'bluing' the surfaces to be lapped with a marker pen to see which areas needed taking down more. The end of the tool was significantly uneven so I touched that up freehand on the bench grinder to flatten it when it became apparent that 200 grit lapping wasn't cutting where it needed to. There was an existing micro-bevel on the leading side, which I kept. Finally I 'dubbed' the leading corner vertical edge on the 1000 grit to give it a very slight nose radius. A test cut on brass gave a very nice finish when turning.<br />
<br />
''Ian B has purchased some spare 8mm HSS tool blanks - talk to a lathe trainer if your proposed lathe work needs custom ground HSS tooling.'''<br />
<br />
=== Brazed Tungsten Carbide Tools ===<br />
Somewhat of a half-way house between hand ground HSS tooling and insert tooling with the disadvantages of both and some more besides - e.g. they are much harder to sharpen. So why do we bother? Some tool geometries would be awkward and tedious to hand grind, and Chinese import brazed carbide tooling is about half the price of similar HSS tooling, and far more readily available. Also, for space constrained tooling like boring bars, if you want carbide, for insert tooling, the size of the insert and its clamping seriously limits the minimum hole diameter you can work in. I have purchased a set of 3/8" shank brazed carbide tipped boring bars, but we currently cant sharpen them, due to lack of a diamond grinding wheel. <br />
<br />
=== Tungsten Carbide Insert Tools===<br />
Decoding ISO insert tooling part numbers: https://www.cutwel.co.uk/blog/learn-the-turning-tool-iso-code-system<br />
[[File:Carbide set.jpg|800px|thumb|left|Our set of Tungsten carbide insert lathe tools (before the new inserts were fitted)]]<br />
<br />
{| class=wikitable<br />
|+ Tools, left to right, (+ last across top):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| SSKCR0610H06 || 75° through boring || SCMT06204 || Long || 6 || 6.34 || ''4.33''<br />
|-<br />
| SSSCR0610H06 || 45° deep facing, internal chamfering || SCMT06204 || Long || 6 || 6.13 || ''4.58''<br />
|-<br />
| SWUCR0610H05 || 93° boring, deep facing || WCMT050308 || Long || 6 || 6.22 || ''4.48''<br />
|-<br />
| SWGCR0810E05 || 90° RH turning & facing || WCMT050308 || Short || 8 || 8.25 || '''2.45'''<br />
|-<br />
| SSSCR0610E06 || 45° turning, chamfering || SCMT06204 || Short || 8 || 8.75 || ''1.93''<br />
|-<br />
| SSBCR0610E06 || 75° RH turning, chamfering || SCMT06204 || Short || 8 || 8.72 || ''1.98''<br />
|-<br />
| LW0810R-04 || 60° external threading || JCL15-120 || Short || 8 || 7.44 * || ''3.28''<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || 8.23 || ''2.5 ?''<br />
|-<br />
| LN0813R-04 || 60° internal threading || JCL15-120 || Long || 7.95 || 7.44 * || ''3.28''<br />
|}<br />
<br />
{| class=wikitable<br />
|+ More Tools, (loose in tin):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || ~8.5 (not in use) ||<br />
|-<br />
| [https://www.glanze.co.uk/product/glanze-12-mm-60-degree-metric-internal-threading-tool/ Glanse SIR0012K11] || 60° internal threading bar || 11IRA60 || Long || 12 dia || ??? || ???<br />
|}<br />
''Shim stack heights in bold are tested, in italic are only calculated.'' ''Tip heights marked * are with new JCL15-120I inserts. The single remaining plain JCL15-120 insert has a slightly higher tip height.''<br />
<br />
Carbide tooling typically requires two to three times more speed than HSS and at least a couple of 'thou' depth of cut for best results.<br />
<br />
Chatter can rapidly kill carbide tooling by chipping the cutting edge. To improve rigidity and reduce the risk of chatter, the cross-slide and compound gib screws need to be well adjusted so there is minimal play in the slides, tool stick-out should be minimised, the four way toolpost should be kept over the cross-slide, and the work should be kept close to the chuck (or otherwise supported by tailstock or steady rest) to avoid excessive deflection.<br />
<br />
Thermal shock is almost instant death to carbide, and when dry cutting the insert tip can run very hot, so do not add extra cutting fluid manually during the cut. Pre-apply what you need, evenly, before starting the cut.<br />
<br />
Parting off or facing to center is high risk - if the tool tip is even slightly below center or if tool or work deflection takes it below center, the work will tend to climb over the tool tip as the cut approaches center, breaking the insert. To avoid this, the tool should be shimmed slightly above center, sufficient to allow for work and tool deflection, and unless very close to the chuck, a steady should be used. Its often preferable to part to a couple of mm dia. remaining then stop and saw through the remainder. Parting off hollow parts is much lower risk.<br />
<br />
Further investigation of the Tungsten carbide insert tool height situation is not encouraging - the so-called 'set' in question does not have a consistent tip height ''(see above table)''! In a real set, the insert seats *should* be machined allowing for the insert thickness to bring all the cutting edges to the same height with respect to the shank underside. However if you place them tip to tip on a table its easy to see there is considerable height variation, so they need to be individually shimmed (or at best, one machined shim will only be right for two or three tools). At this time we don't have dedicated shim stacks for each tool.<br />
<br />
A 2.42 mm thick shim brings the SWGCR0810E05 90° RH turning & facing tool almost exactly to center height, and good results were obtained turning 1" steel pipe. However facing 50mm steel bar stock to center found it to be slightly low, leaving a fractionally under 0.05 mm 'pip' so it needs another 0.03 mm to bring it fractionally above center. Fractionally too high is generally preferable to fractionally too low, due to tool deflection, so adding an 0.05 mm shim to the stack should produce optimum results.<br />
<br />
==== Inserts ====<br />
Ian B has purchased the spare inserts we needed in sets of five. He even was able to get the CK3 parting-off inserts which had been difficult to source!<br />
<br />
Inserts used in above tool set:<br />
* 3x SCMT06204 (square, indexable) https://www.rdgtools.co.uk/acatalog/SCMT-06-Carbide-Insert.html<br />
* 2x WCMT050308 (triangular, indexable) https://www.rdgtools.co.uk/acatalog/WCMT-05-T3-08-5XTIP-8813.html<br />
* 2x JCL15-120 (60 deg threading point) https://www.rdgtools.co.uk/acatalog/X5-JCL-15-120L-THREADING-TIPS-60-DEGREE--X5-TIP---23455.html<br />
* CK3 (parting off) https://www.rdgtools.co.uk/acatalog/CK3-CARBIDE-TIPS---PARTING--BOX-OF-5PCS--9437.html<br />
<br />
Inserts used in other tools:<br />
* 1x CK3 (as above) also missing from spare parting off tool<br />
* 1x 11IRA60 in Glanse threading bar + 1x spare<br />
<br />
=== Drills ===<br />
Various sizes of center drills are kept in a plastic bag next to the wooden accessories tray. There's also a small box of 2.5 mm center drills.<br />
<br />
We have a set of 11 TiN coated HSS drill bits from 1.5 to 8 mm, (in a cylindrical plastic index box) for tailstock drilling of brass, aluminium and non-abrasive plastics. To keep them sharp enough for the precision work we expect from the lathe, please don't use them for steel or reinforced plastics, and don't borrow them for non-lathe use. Metric and US [https://littlemachineshop.com/reference/numberdrillsize.php numbered]/[https://littlemachineshop.com/reference/letterdrillsize.php lettered] general use HSS drill bits are kept in two red metal index boxes next to the drill press.<br />
<br />
== Using the Lathe ==<br />
=== General ===<br />
A cutting speed chart for HSS tooling, published by Model Engineer magazine can be found [https://www.model-engineer.co.uk/sites/7/documents/cutting%20speed%20chart.pdf [here<nowiki>]</nowiki>]. The second row is the target feed rate and the rest of the chart, apart from the diameter column is RPM.<br />
<br />
For carbide tooling cutting iron and steels, recommended speeds are generally three times higher than for HSS, but the CJ18A 2500 RPM max. spindle speed (in high gear) means you can only reach the optimum speed range for over 15 mm dia work. For small diameter work, HSS tooling may well be a better choice.<br />
<br />
An online metric speeds calculator is here: https://www.cgtk.co.uk/metalwork/calculators/cuttingspeeds <br />
<br />
How to do the maths to calculate speeds and feeds: https://www.cutwel.co.uk/blog/speeds-feeds-made-easy<br />
<br />
Making dimensioned parts is primarily done by touching off the tool tip on a reference surface (with the lathe stopped, turning the chuck by hand), zeroing the handwheel dial, then manually counting turns and divisions. When backing off the tool its best to do so by exactly one whole turn so you don't forget the previous dial position. Stopping and measuring the work before taking the final cuts is essential if high accuracy is required. ''I've changed out the dial setscrews for flat tip ones with a tiny slug of solder under them so the dials are now friction fit on their shafts. i.e. if you hold the handle firmly taking up the backlash in the direction of cut, you can zero the dial just by grabbing and twisting it.''<br />
<br />
Carriage movement is less easy to measure as the handwheel is uncalibrated and advances an awkward bit over 19.2 mm per turn. Your options here when shoulders or other features must be exactly positioned are, in order of increasing accuracy: <br />
* Use measuring instruments, scribe the work at the desired length then work to the scribed line. Its often convenient to black the work with a permanent marker, then scribe with the tool tip, turning the chuck by hand.<br />
* for short distances, lock the carriage and use the compound, set parallel to the work<br />
* Set up a long travel dial indicator to measure carriage motion. <br />
N.B. with the leadscrew stopped, and the threading dial engaged, with its default 16 tooth gear, it will make one turn for every 24 mm of carriage movement (2 mm/div). This isn't accurate enough for positioning but is sufficient to check you aren't out by a whole mm or more.<br />
<br />
Do not allow any solvents to contact the chuck guard clear plastic as it will make the plastic brittle, or even craze it, and try to avoid melting it with the work light!<br />
<br />
=== Slide Locks ===<br />
* The carriage can be locked to the ways using the M5 hex screw through the top of the saddle to the left of the cross-slide. Double check the leadscrew is disengaged and the half-nuts open before locking it. Lock it when facing.<br />
* The cross slide can be locked by a M4 socket headed cap screw just in front of its middle gib screw. Locking the cross slide is helpful when turning very shallow conical features where the cross slide handle is in the way of the compound.<br />
* The compound slide can be locked by a M4 socket headed cap screw in line with the edge of the toolpost mount on the side with the gib adjustment screws. In normal use it should be kept backed off half a turn but it is desirable to tighten it for parting off operations to keep the resulting end faces flat.<br />
<br />
=== Chucks and Chuck Jaws ===<br />
==== Terminology ====<br />
* Inside jaws have steps on the outside to grip the ID of hollow work, but can also be used as outside jaws on small diameter parts (i.e. that fit through the spindle). <br />
* Outside jaws have steps on the inside to grip the OD of the work.<br />
* Universal chucks have a scroll plate with a spiral screw thread that moves all the jaws.<br />
* Independent chucks have individual adjusting screws for each jaw.<br />
<br />
==== The Chucks ====<br />
* The three jaw universal chuck can only grip near round or hexagonal work, which it centers, but its concentricity is not perfect so e.g. if you reverse the work and continue turning at the same diameter from the other end, you will see a line where the turned surfaces meet. It has separate sets of inside and outside jaws, and we normally keep the inside set installed to use as outside jaws for small diameter work.<br />
<br />
** Our jaws are individually numbered, stamped in the groove. They must be fitted in the correct sequence. The jaw slots are not clearly marked. Lowest runout for small dia. parts is achieved if you fit the jaws with #1 anticlockwise of the makers mark, then continue anticlockwise for #2 and #3.<br />
** A large strong rubber band is a great help getting all the jaws started on the scroll together - with slots #1 and #3 above the centerline and the scroll thread outer tip between #1 and #3, insert jaws #1 and #2 and put the rubber band round them to keep them in their slots. Insert jaw #3 and stretch the rubber band over it to hold it up into its slot. If the scroll was positioned correctly, all jaws should be at the same initial radius. The jaws can now be cranked in with the chuck key and they should all engage in step so they meet in the middle.<br />
:: ''Mini-lathe.com have the best instructions for [https://www.mini-lathe.com/mini_lathe/chucks/chucks.htm#Installing_Chuck_Jaws changing the jaws].'' <br />
<br />
* The four independent jaw chuck can grip most roundish or squarish work, which can either be carefully centered by the user, or deliberately gripped off-center. <br />
** Its jaws are reversible so can be swapped from inside to outside by simply cranking each jaw out and reinserting it the other way round, one at a time. DON'T move the jaws to different slots as they are likely to bind.<br />
** When setting up to face the sides of rectangular objects held crossways, it may be helpful to use both inside and outside jaw orientations, in symmetrical opposing pairs.<br />
** Its screws move their jaw 1/8" (3.125 mm) per turn<br />
<br />
* The jaws must '''never''' protrude from the chuck OD by more than one step, and for safety, its preferable they don't protrude at all, as they make the gap between the front of the bed and the chuck body an even more unforgiving meat grinder, and as the number of teeth engaged with the scroll or screw decreases, they loose strength, just when you need it the most to grip larger/heavier work. <br />
<br />
''Neither chuck is well suited to gripping tapered work safely. When seating work that doesn't quite fit through the chuck bore (which is larger than the 20mm spindle bore limit), be careful that it isn't seating on the chamfered edge of the chuck bore as it is far to easy to get the work slightly cocked so it doesn't run true.''<br />
<br />
==== Changing Chucks ====<br />
* When changing chucks, use the small grey plastic mat to protect the ways under the jaws in case you drop the chuck.<br />
* The spindle nose has two patterns of holes - the three hole pattern is for the three jaw chuck and the faceplate, and the four hole pattern is for the four jaw chuck. One hole is shared between the patterns, and is marked on the spindle nose.<br />
* To fit a chuck:<br />
** First check that the spindle nose and chuck back and recess are free of swarf, grit or other debris. Any foreign objects will tilt the chuck causing excessive runout and may mar the surfaces.<br />
** Remove the nuts and split lock washers from its studs, line its studs up with the hole pattern (preferably with the stud nearest anticlockwise to the makers mark through the marked spindle hole), fit and hold it in place with your right hand, and with your left, get the lock washer and nut on the top stud, and take up the slack.<br />
** One one nut is on, you no longer have to worry about dropping it, and can work round fitting the remaining washers and nuts, taking up the slack on each as you fit it. <br />
** Next, work round again getting them all finger tight, then tighten them gently, and finally work round fully tightening them. <br />
* Removal is the reverse of refitting. Put the washers and nuts back on the chuck's studs so they don't get lost.<br />
<br />
==== Gripping Threaded Work ====<br />
It is generally undesirable to chuck work gripped on a screw thread, as it is difficult to hold the work securely and get good concentricity while avoiding crushing the thread crests. However, if one must, one of the better ways of doing so is to wind a wire helix to fit the thread then clamp on the outside of the wire so it seats on the flanks of the thread. The wire should be mild steel or soft iron for steel parts and copper for aluminium and brass parts, single strand, round and of uniform diameter a little less than the thread pitch. It can be wound on the lathe, in reverse, by chucking a sacrificial mandrel of the same diameter and thread pitch, hooking the end of the wire round or under the jaw, against the direction of rotation, then holding the other end of the wire under tension with pliers and starting the lathe dead slow. Once wound and removed from the mandrel, the ends must be trimmed then it should be screwed on to the threaded work to provide a surface to chuck on.<br />
<br />
=== Faceplate Work ===<br />
Faceplate work is probably the most dangerous operation you can (or rather should) perform on a lathe. The working area is a large diameter spinning surface with protruding clamps to fixture the part that it is impractical to guard. Protruding clamps, studs, nuts etc. are very difficult to see at speed.<br />
<br />
'''Treat the faceplate with great respect and caution if you wish to continue to be able to count to ten on your fingers!''' <br />
<br />
The 65 mm cross-slide travel vs the 80 mm faceplate radius is a serious limitation that may require creative compound, toolpost and tool setups for larger parts, and doing full face cuts in two sections.<br />
<br />
''It is common practice to skim the faceplate to ensure it runs true. We have not (yet) done this, and wont till the spindle is in better bearings and the nose reground to minimise runout.''<br />
<br />
==== Clamping ====<br />
Open ended/sided clamps should be oriented so that cutting forces drive the work towards the clamping bolt/stud, not out from under the clamp. Minimize the protruding length of thread past the clamping nut, if necessary using sacrificial bolts or studs you can cut to length, or even using a long M8 stud for one of the faceplate mountings, so you can get a clamp nearer to the faceplate center. Double-check all clamps are secure, manually turn the faceplate to check the work and clamps clear the ways, top-slide and toolpost, and stand out of the 'line of fire' (a disc extending from the faceplate) when spinning up the work for the first time. <br />
<br />
If you need to machine close to a clamp, consider marking a safe limit circle on the faceplate and work with a marker pen to make it easier to see how close the cutting tool is to crash disaster. <br />
<br />
I strongly advise reading chapter two of Tubal Cain's book "Workholding in the Lathe" several times before your first faceplate setup, and if possible get another experienced lathe user to check your first few setups before spinning them up.<br />
<br />
==== Chuck Guard Removal ====<br />
The faceplate is too large diameter to fit under the chuck guard, but the guard has an interlock switch wqhich must be closed for the lathe to run. The guard is now fitted with wing nuts so it can be removed allowing the the interlock switch to close when using the faceplate. It *SHOULD* *ALWAYS* be refitted if a chuck is fitted, except when turning work too large to clear the guard. <br />
<br />
''The chuck guard is primarily there to make it very difficult to start the lathe without removing the chuck key and to reduce the area of large diameter spinning surface exposed. It may slow down the projectile if a chuck sheds a jaw but is unlikely to stop it. Also it serves to contain coolant spray spun off the chuck. As we don't use flood coolant this usually isn't an issue for us. As setting up for faceplate work doesn't use a chuck key, and the most hazardous zone is the face of the faceplate, with its spinning projecting clamps, with full access required for machining operations, which a guard would not cover, the consensus is that removing the guard is an acceptable risk.''<br />
<br />
=== Turning and Facing ===<br />
We are getting good results in aluminium, brass, and even steel using HSS cutting tools in quick-change tool holders, and the ~ 94 um/turn power feed. Unfortunately due to lack of rigidity in both the machine and smaller diameter parts, if you don't want the outer end to be over diameter, a light final cut and multiple 'spring' passes will probably be required.<br />
<br />
For aluminium, a sharp HSS tool and 0.5 mm (20 div) depth of cut gives good results with power feed for rapid stock removal. Its also easy maths as each cut takes ~ 1 mm off the diameter. Finish cuts should be much finer, 0.1 mm (4 div) is 'in the ballpark'.<br />
<br />
For steel, using carbide insert tooling, a 0.25 mm (10 div) depth of cut is more appropriate, and with pre-applied cutting oil, gives reasonable results with power feed if you use enough speed. The maths is not quite so easy as you are only taking 0.5 mm off the diameter per pass. Again, use finer finish cuts but try to plan your cuts so the final cut is still cutting, not smearing the surface!<br />
<br />
When facing or parting off, some skill is required to turn the cross-slide handwheel steadily to get a decent finish and to avoid shock-loading the tool tip. Increasing the spindle speed in one or more steps to keep up with the reducing diameter is advisable, but avoid speeds that cause resonances (resulting in chatter). When parting off, small through-hole parts may be caught on a thin rod chucked in the tailstock, and pre-positioned inside the work with its tip right up to the parting off position.<br />
<br />
==== Using the Steady Rests ====<br />
For the fixed steady rest, see Blondihacks' Lathe Skills #26 - How To Use a Steady Rest! [[#Youtube_Playlists_&_Videos|{below}]]<br />
<br />
Ours doesn't have ball bearing fingers, so a smooth surface on the work and adequate lubrication are essential. The thumbscrews can only tighten the fingers, so for small adjustments outwards you need to either slack off the clamping nuts or ease them slightly and use a drift against the back of the finger's slot. Once set, check the chuck still turns freely.<br />
<br />
The traveling steady rest needs to run on a machined surface, so at least for the first pass, must follow the tool, so its difficult to avoid using more compound slide overhang than is desirable. An initial surface should be cut next to the chuck or tailstock center before fitting the steady rest.<br />
<br />
Both are a PITA to fit - the fixed one has to have its clamping post inserted up through the bed, and the supplied spanner is useless near the headstock, and the travelling one's mounting holes on the saddle almost invariably need swarf picked out of them.<br />
<br />
==== Turning Between Centers ====<br />
<s>Using a MT3 to MT2 reducing sleeve, the MT2 dead center can be fitted in the spindle.</s> ''Currently the MT3 spindle taper is compromised.'' Alternatively, a soft center can be turned immediately before use in the three jaw chuck, but that must have its 60° point re-cut to concentric if the chuck is disturbed, and needs to be either large enough to bear on the chuck body, or must have a lip to bear on the end face of the jaws to take the axial thrust. Recutting the center is a PITA, as the compound angle must be set to 30° anticlockwise, then reset to a true 0° afterwards. Maybe a right-hand 30° end angle zero rake form tool is the answer, or use the carbide insert tool SSKCR0610H06 as a form tool with the toolpost rotated 15° anticlockwise.<br />
<br />
With the MT2 live center in the tailstock quill, this gives us a center either end of the work to hold it.<br />
<br />
We also need a drive dog similar to [https://littlemachineshop.com/products/product_view.php?ProductID=4473&category=1 this], and the corresponding drive post to bolt to the spindle nose. I have some 25mm bore thick wall iron pipe, which should do nicely. Lengths of the dog's straight tail and of the post TBD after I check how much the center protrudes. N.B. its recommended to tie the tail to the post to keep them in contact so they don't slam. ''Currently we will need to drive from the chuck jaws. Possibly use the exterior jaws with a short soft center gripped on the inside end and drive from the highest step.''<br />
<br />
=== Drilling ===<br />
Always start with a center drill so deflection of longer bits doesn't start the hole off-center. For larger bits (> 5 mm), first drill to the web size, then to final diameter. For a precision hole, drill slightly undersize and ream to final diameter. ''Supply your own reamers!''<br />
<br />
Caution: See note about the quill anti-rotation pin in section [[#Tailstock Quill|Tailstock Quill]] above.<br />
<br />
=== Boring ===<br />
Caution: As the spindle doesn't extend right through the headstock housing, if boring in a through hole, chips tend to fall out the back and tumble in the spindle bore till they fall into the change gears. To avoid this, one should plug the spindle bore with a wad of paper towel or rag and when cleaning up afterwards, use a rod to push it through towards the tailstock, with the chuck jaws (if fitted) wound clear of the spindle bore.<br />
<br />
A swivel bladed hole deburring tool (pale blue handle) can be found in the main room on the windowsill behind the drill press.<br />
<br />
A couple of boring jobs have been bodged with an awkwardly angled turning tool and achieving acceptable effective rake with enough clearance to reach deep enough into the hole has been problematic. I reviewed the tools we had and found none suitable for starting out in a 13mm bore, the max diameter we can (easily) drill. I therefore decided to buy a set of boring bars and make a holder for them. I had difficulty finding anything affordable under 10mm shank - the best low cost option was a [https://www.amazon.co.uk/dp/B07P5LGVBX set of nine 3/8" (9.525 mm) shank brazed carbide tipped boring bars], which would be close to the max capacity of the quick change boring bar holder - if we had one! Unfortunately this holder for our specific toolpost is difficult to find except in a toolpost bundle. Another annoyance is the variable tip height of the set, varying from 1.8 mm to 2.8 mm above the center of the shank.<br />
<br />
I therefore decided to make a boring bar holder of the [https://littlemachineshop.com/products/product_view.php?ProductID=1700 Littlemachineshop.com (USA) style] for use in the four way toolpost, as the additional rigidity will certainly help. Starting with a slightly over 50 mm length of 16 mm aluminium square bar and using the four jaw chuck , both ends were faced and an attempt was made to find its center and center drill it. It was then drilled out to ~9.8 mm after much drama due to blunt drills and drills that cut ~1mm oversize. Too big, but beggars cant be choosers as we didn't have a boring bar holder or a 3/8" reamer. Unfortunately the final hole ended up significantly off center. It was then chucked crossways and ~1 mm skimmed off its thickest side to gain clearance to allow it to be shimmed to height, then one side was slit lengthwise manually with a hacksaw.<br />
<br />
It was fitted to the for way toolpost and loaded with a booring bar, which clamped firmly. A 0.86 mm shim stack brought the tip of the largest boring bar almost spot on center height, with the difference easily accommodated by twisting the tool slightly. The three jaw chuck was then remounted, and a piece of iron pipe chucked for a test. It cuts well and leaves a decent surface finish.<br />
<br />
''The boring bar setup is a work in progress - talk to me before attempting to use them if you have a project that would benefit from boring..''<br />
<br />
ToDo: get something that can sharpen tools tipped with this grade of carbide - it needs some sort of diamond (or possibly CBN) wheel as green grit silicon carbide does little more than polish it. ''N.B. diamond wheels are rapidly eroded by grinding steel, so the supporting steel seat must be undercut with a regular grinding wheel before the diamond wheel can contact it.'' <br />
<br />
We'll also need 50 mm square sheet shims to fit under the toolpost to gain clearance in the toolpost above the tool or toolholder. A 2.4 mm shim would give us about the same above and below spindle center height, and we probably need a small selection of thinner ones.<br />
<br />
=== Thread Cutting ===<br />
The objective is to cut a thread that complies with the ISO metric thread profile. Our lathe is not currently equipped to cut non-metric threads, (with the exception of BA which have pitches based on metric threads of that era).<br />
<br />
[[File:ISO and UTS Thread Dimensions.svg|frame|center|Metric Thread Profile - from the geometry, H is ~86.6% of P]]<br />
<br />
Metric thread data - See 'Preferred Sizes' at: https://en.wikipedia.org/wiki/ISO_metric_screw_thread<br />
<br />
See "Mini Lathe User’s Guide" section '''Threading''' for general techniques *ONLY*, and above for change gears and threading dial setup.<br />
<br />
Amadeal specify the max. thread pitch as 2.5 mm. Any thread pitch greater than 1.5 nn requires the change gears to gear up. When gearing up it is desirable to distribute the ratio as evenly as possible over the two pairs of gears in the geartrain to avoid excessive tooth loading.<br />
<br />
==== External Threading ====<br />
Initially turn work to required Major Diameter, set up change gears and threading tool, touch off on the work, zero the top and cross slide dials, and do a 'scratch' pass to check the pitch. Back off the tool, return the carriage, and re-engage the half nuts on a valid dial line clear of the end of the thread then immediately stop the lathe, and hand turn the chuck till the tool tip is (hopefully) over the scratch to check the thread pickup. If all is good, return the carriage again, restart the lathe and start cutting your thread. <br />
<br />
Methods of doing so vary depending on the size of the thread and toughness of the metal, but straight-in plunge cutting is generally to be avoided as has the highest cutting forces, and does not reliably keep the carriage (and top-slide if set parallel to the work) loaded to avoid pitch errors due to backlash. <br />
<br />
If leaving the half-nuts engaged and reversing the lathe to return to the start of the thread for the next pass, its absolutely essential to back the tool out of the thread for the return pass as it will not follow the path of the cutting pass due to backlash in the geartrain, leadscrew mounts and half-nuts.<br />
<br />
==== Internal Threading ====<br />
''<nothing here yet>''<br />
<br />
== Cutting fluids ==<br />
=== Why bother? ===<br />
[https://youtu.be/mRuSYQ5Npek Watch this video] and contemplate what's actually happening to that thin ribbon of metal being removed. Most of the lathe's motor power is being turned into heat by internal friction in the chip being removed in the zone around the cutting edge, and surface friction at, and immediately behind the cutting edge, near-instantly heating the chip by up to several hundred degrees. Reducing the surface friction using a suitable cutting oil reduces the strain on the machine as a whole, and reduces workpiece and tool heating (and thus expansion) with consequent improvements in maximum usable feed and depth of cut, surface finish and accuracy. It also drastically increases the life of the cutting edge.<br />
<br />
=== Practicalities === <br />
We don't have a coolant system for the lathe and *really* don't want the maintenance hassles of using soluble cutting oil/coolant as if used infrequently its a PITA to keep recirculated high water content cutting fluids from going rancid and stinky, and they can also rust the ways, so even a total loss gravity feed system is problematic. Therefore if dry machining doesn't give a good enough finish, we tend to use oil applied topically, by hand to the work. <br />
<br />
* Hard brass is typically free-turning without oil, however some light oil for the final cut can improve surface finish, but with the disadvantage that it will increase loose chip buildup on the tool as hard brass typically forms short spalls or splinters rather than curly chips.<br />
<br />
* Many Aluminium alloys tend to be gummy, and Paraffin or other mineral spirits mixed with a little oil can help prevent the aluminum welding to the tool edge. WD40 will do at a pinch, but its messy to apply from a spray can.<br />
<br />
* Steel really needs *GOOD* cutting oil. Lard oil is the traditional choice for steel. If there are any objections to lard oil, we should bite the bullet and get some commercial dark high Sulphur cutting oil, but beware, many such oils use an additive package that includes lard oil.<br />
* Cast iron (except ductile) should be cut dry, as the carbon micro-inclusions self-lubricate it, and the carbide in the dust (primarily Cementite) are very abrasive, so tend to form a grinding compound if mixed with oil. <br />
<br />
I've sorted out an oil pot lid with a 1/2" brass collar soldered in to give a nice smooth sided hole, for ease of use and to minimize the risk of spills when using a brush to apply cutting oils, and got some dirt-cheap brushes. It fits Shippam's paste (and similar own-brand spread) jars and I've found several jars and ordinary lids to seal them for storage. Unfortunately it isn't the easiest to get this type of jars' lids back on square so they seal properly, and if you over-tighten them and there's a temperature change, they can be a total <expletive> to reopen. Using the rubberised handles of a large pair of pliers to grip the jar lid just above its rim is the best option, and avoids damaging the lids.<br />
<br />
''N.B. For the smaller brushes, the glue holding the bristles in is attacked by paraffin. To prevent loss of bristles, crimp the aluminium ferrule of each new brush of this type before use.''<br />
<br />
We have, in labelled jars:<br />
<br />
* Sulphurised Lard oil thinned with paraffin. Best choice for heavy cuts and threading in steel but stinky.<br />
* Lard oil thinned with paraffin. Good for steel and acceptable for softer copper alloys<br />
* Paraffin with a trace of light oil. Good for aluminium, and can help prevent squealing chatter on finish cuts in brass.<br />
<br />
I've also got some paraffin wax (in the form of a stubby candle), which can be applied lightly (under power) to brass and aluminium stock especially on the finish pass. It makes less mess than oil but unfortunately tends to build up on the tool tip, making it difficult to 'work by eye' without frequent pauses to clean the tool tip.<br />
<br />
We've also got a tin of [https://www.rocol.com/products/rtd-compound Rocol RTD cutting compound], which is a thick paste. Its highly recommended for drilling and tapping steel (in the drill press or by hand), but as a paste, is less useful for general lathe work unless thinned to a fluid consistency, e.g. with paraffin or white spirits. OTOH its certainly worth trying for high speed facing steel as it is less likely to get flung off.<br />
<br />
== Cleaning and Maintenance ==<br />
Swarf is a significant cut hazard to the operator, especially stringy swarf from cutting steel. Never touch it bare-handed - always use a tool e.g. a brush, or a hook, or needle nose pliers for grabbing long swarf.<br />
<br />
* After use, brush all swarf off the toolholder, compound and cross slide etc. ways and leadscrew. Ian B has blocked off the opening at the headstock end of the rear splashguard (to try to keep swarf out of the motor), so one must sweep the swarf towards the open tailstock end and catch it in a dustpan or similar. Preferably, also thoroughly clean out the chip tray under the lathe, but at least sweep out visible swarf.<br />
* Wipe up any cutting fluid residue and re-lubricate affected sliding surfaces with way oil.<br />
* Do not solvent clean the chuck guard, as it will make the plastic brittle, or even craze it. Water with a little detergent is permissible for cleaning it, with the guard totally removed from the lathe.<br />
<br />
Before engaging the half-nuts for power feed/threading, check the leadscrew is clean! ''Best cleaned under power, with a toothbrush.'' <br />
<br />
'''Caution:''' The traverse gears behind the carriage handwheel are in an open-backed housing and tend to become packed with swarf! Swarf buildup here will result in jerky carriage movement. Clean out as much as you can with a toothbrush ...<br />
<br />
===Lack of lubrication and/or swarf or dirt build-up can be disastrous===<br />
* If using the change gears/power feed, lack of lubrication of the B-C stub shaft center pin or either leadscrew end bearing can result in seizure and immediate destruction of one or more gears in the gear train or worse. <br />
* Small pieces of swarf can get between the saddle and ways, or into the slides degrading accuracy, possibly permanently if hard swarf scores them, or jamming them. The carriage handwheel gears behind the apron are notorious for accumulating swarf, and swarf buildup on the leadscrew can prevent the half-nuts engaging properly, resulting in scrapped work, and possibly stripped half-nuts. <br />
* Metal swarf can get into the motor (''though Ian B has modified the rear chip catcher to reduce the risk)'' or into the control box via the leadscrew, and short-circuit stuff. At best it will blow the fuse and need a strip-down to clean it out, at worst it may require a replacement [https://www.amadeal.co.uk/acatalog/Speed-Control-Circuit-Board--12amp-AMA_SP_CJ18_SCB12.html#SID=12 speed controller] ''(currently £96)'' and/or [https://www.amadeal.co.uk/acatalog/550W-motor-for-CJ18A-Mini-Lathe-467.html#SID=240 motor] ''(currently £105)'' and possibly other electrical parts. We should probably fit a [https://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C3-Mini-Lathe-Spares/C3-256-Leadscrew-Grommet-Dustproof-Cover C3-256 Leadscrew Grommet] to keep swarf out of the control box, as it tends to drop onto the 'Filter' board which is mounted horizontally, below the leadscrew.<br />
* Grit from grinding, sanding etc. forms a grinding paste with the way oil, and will rapidly wear out the ways, saddle and slides. Keep grit off at all costs e.g. by covering the ways and slides during grinding/sanding operations, and if there's any chance grit has gotten where it shouldn't, clean and re-lubricate *BEFORE* moving the carriage or slides, then move the carriage and slides, wipe down where they were with a clean paper towel and check there's no remaining traces of dirt other than clean way oil on the paper towel. If it doesn't come clean when you re-lubricate and move it again, a full strip down may be required to solvent clean and relubricate the precision sliding surfaces.<br />
* Although a metalworking lathe *can* be used to turn hardwood, wood dust and small chips are extremely pernicious, as they get everywhere, even clinging to clean surfaces, are abrasive due to their silica content, and are hygroscopic, promoting rust. An even more thorough clean-up than after using abrasives is needed, immediately afterwards. Oily wood dust and fine wood chips in significant quantities are a fire hazard, even in the trash bin.<br />
<br />
===Lubrication===<br />
See section: "Lubrication" in LittleMachineShop.com "Mini Lathe User’s Guide" [[Ian_M's_Lathe_Notes#Manuals|(below)]]. As we usually only open two nights a week, in the table on page 16, Daily lubrication becomes Weekly and Weekly becomes Monthly.<br />
<br />
===General Maintenance===<br />
* The grubscrews holding the cross-slide and compound slide dials tend to loosen due to vibration and use of the dials. Keep them snugged up, but not so tight the dials cant be set without an Allen key.<br />
<br />
* The screws holding the cross-slide nut tend to work loose due to vibration. Crank the handle to and fro through the backlash and visually check there is no movement of the screw heads in their holes. If there is, see the [[#Excessive_cross-slide_backlash|notes below]].<br />
<br />
===Removing the Carriage===<br />
Its possible to remove the carriage from the bed for cleaning etc. without dismantling it. The only stop to its motion is the righthand leadscrew bearing.<br />
<br />
Start by removing the tailstock. Crank the carriage to the tailstock end then remove the leadscrew bearing (two screws and a nyloc nut on the leadscrew end). With the half-nuts open, hold the leadscrew centered in them and crank the carriage off the end of its rack, then slide it off the end of the bed.<br />
<br />
Refitting is the reverse of removal, except (if its gibs are correctly adjusted) the carriage will be very tight on the end of the bed ways so may be difficult to work onto the ways without a stack of blocks of wood or similar to support it at exactly the right height. The righthand leadscrew bearing must be refitted with the carriage as close as possible to it and the half-nuts firmly closed to support the leadscrew at the correct height to hold it in alignment while the screws are being tightened. The nyloc nut controls leadscrew end-play. Fully tighten it then back it off slightly till the leadscrew turns freely with its change gear removed.<br />
<br />
If the Apron has been off, refit it with the screws no more than lightly finger tight and only finally tighten them after checking lead screw engagement at both ends of the carriage travel and that the rack and pinion operates smoothly over the full travel.<br />
<br />
== Issues and Annoyances ==<br />
As of September 2023 - mostly resolved, apart from the spindle bearings and runout, the lathe is in better condition than it has been for a number of years.<br />
<br />
===Four Jaw Chuck has two jaws too tight===<br />
Fixed 27/10/2023: Two of the chuck jaws were tight in their slots, making precise adjustment difficult due to lack of 'feel'. Moving the jaws round the slots showed the problem mostly followed the jaw not the slot. The grooves in the opposite sides of the affected jaws that run in the chuck slots were slightly out of true, and the rails either side of the slots were slightly too thick towards the center. Due to the difficulty of seeing the high spots, after cleaning up and deburring the jaws didn't do enough to ease them, I decided to grind the top of the rails where they were binding. Several repetitions of spotting with Engineer's blue, grinding, then diamond filing the high spots has eased them enough. I cleaned everything, greased the jaw slides and screws, and refitted the studs so the chuck is now fit for service.<br />
<br />
''N.B. Don't move the jaws to a different slot - the formerly tight jaws *must* stay in the slots furthest from the makers mark.''<br />
<br />
===Excessive Runout===<br />
Mostly fixed 24/10/2022: I ground the chuck seating surface of the spindle nose (outside lip) to under half a thou runout. This also cleaned up several burrs. It would be possible to do better, but that would need good spindle bearings, and a more rigid toolpost grinder mount.<br />
<br />
Our spindle nose was damaged years ago by a person with little mechanical aptitude (who shall remain nameless) beating it up with a hammer mushrooming the spindle nose. We are getting several thousandths runout at the end of the MT3 bore, a MT3 to MT2 reducer sleeve in it runs visibly out of true, as does the spindle nose flange. When you put a chuck on it, the runout is magnified by the distance from the spindle nose. Ideally we would replace the spindle when we change the bearings but its £52 [https://www.amadeal.co.uk/acatalog/4-Spindle-Upgrade-Real-Bull-Mini-lathe-CJ18-series-AMA_SP_CJ18_003RB.html#SID=9 from Amadeal] and money is tight. It may well require more work after the bearing upgrade. Once good bearings are in, if we can borrow a decent MT3 arbour as a reference, we should consider skimming the bore.<br />
<br />
===Spindle bearings===<br />
* The spindle bearings appear to be close to worn out. They are notably noisy when running, and there appears to be more slop in the spindle than is desirable. There is notable resonance around 600 RPM, and surface finish of end faces is often poor. We have some ideas for possible replacement/upgrade, but it requires a major teardown.<br />
<br />
: The original bearings are allegedly 6206-2RS or 6206-ZZ deep groove ball bearings - 2RS codes rubber seals both sides and ZZ codes metal shields. Although the deep groove gives reasonable ability to withstand axial loads, the bearing balls point contact means they are vulnerable to [https://en.wikipedia.org/wiki/Brinelling brinelling] due to shock loading. The jammed on three jaw chuck didn't help this, as before we skimmed the spindle nose lip, it had to be driven off using a bar through the spindle bore, shock loading the bearings every time. Also even a minor 'crash' could have brinelled them due to eccentric shock loading, and the lathe has previously been crashed badly enough to need drive gear replacement. There are also issues with the 'approved' method of spindle and bearing removal from the headstock brinelling them, even if you don't abuse the spindle nose with a hammer!<br />
<br />
: A possible replacement is 30206 tapered roller bearings. The new bearings are slightly thicker so the plastic spindle spacer (15) needs to be machined to length to get the 45 tooth spur gear that drives the change gears laterally aligned with the tumbler gears. If a temporary replacement (3D printed?) is fitted, the lathe can be run (without power feed capability) so this can be done on the lathe after fitting the new bearings. As tapered roller bearings have line contact, they are significantly more resistant to brinelling.<br />
<br />
: ''See [[Talk:Ian_M%27s_Lathe_Notes]] for notes, links etc. for this upgrade.''<br />
<br />
===Motor stuttering===<br />
* Fixed 21/09/2023: The motor was running very erratically and it was very difficult to set a speed. Several loose connections were found in the control box, mostly loose female spades to the motor controller board, but also a dry jointed braking resistor on the 'Filter' board, and an inhibit wire completely off its terminal on the forward/reverse switch, making intermittent contact. After tightening and/or remaking all affected connections, it was much improved but still not right below 300 RPM. The remaining issues were due to poor wiper contact in the speed control pot, and stripping it, cleaning the track and contact ring and re-tensioning the contacts resulted in the motor now running smoothly over the full speed range. The speed is slow to settle, and while part of that is probably the lag in the digital tach, I suspect that the KBIC motor speed controller isn't properly tuned as it was (allegedly) previously replaced.<br />
<br />
===Drive belt slipping===<br />
* Fixed 28/9/2022: During testing the motor after the above issue, it was noted that the chuck could be stalled, slipping the drive belt, with not much torque. The drive belt was determined to be loose and a bit worn, but still in acceptable condition. <br />
<br />
: Access for servicing the belt requires removing the control box ''(2 spades to ZVR switch disconnect the supply, speed sensor and motor simply unplug from the 'filter board')'', the motor cover, chuck guard switch assembly + wiring cover, the change gear 'A' (drive) shaft carrier assembly, and the tumbler gear assembly. See https://youtu.be/EkxlIz01BdA for disassembly/reassembly, though on our lathe, the speed encoder ring on the spindle prevents the belt cover from being fully removed without disturbing the spindle nuts. There is enough room to work with it loose, but still trapped by the encoder ring. Also, unlike the video, if the 'jack' screws under the headstock are correctly adjusted, and the studs aren't excessively bent, there is no need to make custom studs. <br />
<br />
: It turns out that our lathe was missing the M6 hex headed jack screws that press the motor down to resist the belt tension, and the motor had cocked out of position at a severe angle. I know Ian B had had considerable trouble adjusting it after the motor fault back in October 2022, and I believe it had been getting slowly worse ever since. The jack screws were probably mistaken for headstock fixing bolts during disassembly after the crash that resulted in the metal Hi/Lo gears being fitted, then lost. The penny washers on the studs had dished, so I turned them over and backed them up with smaller washers and switched to Nyloc nuts so they cant back off due to vibration. N.B. There is a packing washer on the motor side on one of the studs, presumably so the shaft is true to the ways. Adjusting the motor is awkward to say the least. One has to slack the stud nuts off a lot, pry under its rear end to lift it enough to be parallel to the ways, snug the stud nuts, check alignment, then set the jack screws and their lock nuts to hold it there, and finally tighten the stud nuts. <br />
<br />
: Tension: According to Sieg, it should be possible to twist the belt 90° mid span with a light finger grip. Other sources say 1/32" - 3/32" deflection mid span with light finger pressure.<br />
<br />
===Speed display blanking===<br />
* The speed display has been intermittent, blanking and flashing 8888 and 0 at certain speeds for as long as I have been using the lathe. Finally on 18/07/2022 it failed completely, with no display. I removed the display module and bench tested it - the pins are labelled 5V GND PL PE, PE is frame ground and PL is a TTL level pulse from the speed sensor - confirming that it was in good working order. My suspicions then turned to its power supply on the 'Filter' board. With both the sensor and display unplugged, the 5V rail was found to have a only a couple of volts, but the unreg DC was 17V and stable. Replacing the 78L05 5V regulator restored the 5V rail and normal operation.<br />
<br />
: ''I conclude its been failing for a while with high load current due to speeds with more lit segments causing it to drop out, resetting the speed display, causing it to blank, lowering the current enough for the regulator to recover, then the display MCU lamp tests (8888) then re-acquires the speed, repeating ad-nauseum till the speed is changed. I don't like the design as the high input voltage results in excessive dissipation.'' <br />
<br />
: ''ToDo: If it fails again, bench test display to measure its worst case current consumption, then fit an appropriate dropper resistor to reduce the 78L05 dissipation.''<br />
<br />
===Quill spinning when drilling===<br />
* The quill was tending to spin while drilling because its anti-rotation pin (a M5 dog tip setscrew) was sheered. I've removed the debris, aligned the scale with the top of the tailstock and fitted a longer M5 dog-tip setscrew to replace it, with a nut to lock it at the correct height. N.B. the pin isn't that 'meaty' so if using big drills in tough metals, to prevent shearing it, it should be backed out so the quill can be turned by hand and unwanted rotation controlled by being quick with the quill lock if it starts to spin, or even using a close fitting rod in one of the chuck key holes with plastic tube over it to protect the ways. <br />
: ''If the screw sheers again, the quill will need to be removed and the tailstock taken off the lathe so the sheered tip can be shaken out, and if the setscrew is difficult to remove it probably means the threads are mangled where it sheered. Try driving it right through with the quill out.''<br />
<br />
===Sloppy quick change toolpost locking mechanism===<br />
* Once the dovetail clamp screw was slackened, there was nothing preventing the dovetail twisting or cocking significantly, and friction with the toolholder made it tend to do so, making toolholder insertion and removal more difficult unless the clamping screw was backed off excessively. I added a compression spring around the clamp screw inside the toolpost to push the dovetail outwards so it mostly retains alignment when open, allowing toolholders to slide on or off cleanly with far less screw slackening.<br />
<br />
===Leadscrew rubbing===<br />
* The leadscrew shaft is rubbing on the insulating separator inside the control box. Unfortunately the corner of the relay on the Filter Control Board (#160) doesn't allow enough clearance. Although the friction isn't much of a problem at high reduction ratios, e.g. 16:1 power feed, it increases the stress on the change gear train, and may be problematic when threading at feeds above 1:1. ''Possibly pack out the control box mountings by a couple of mm.'' <br />
<br />
===High/Low lever backwards!===<br />
* The high-low drive gear selector behind the headstock is incorrectly labelled and differs from the manual: low gear (which we normally use) is with the lever towards the tailstock. ''I suspect that the gears in the headstock were refitted the wrong way round when it was upgraded to metal gears.''<br />
<br />
: ''ToDo: Get it reassembled the right way round during the spindle bearing upgrade!''<br />
<br />
===Carriage lock fouls top slide===<br />
* The T handscrew has been replaced with a M5 hex headed bolt, to permit access when the top slide is over it. An 1/4" drive 8mm socket is usually left on it, but needs to be removed when the full cross slide travel is needed. The small (4 jaw) chuck key is near enough 1/4" to use for it. If you need to (un)lock it while the compound is over it, you'll need an 8mm spanner. ''The [https://www.amadeal.co.uk/acatalog/Mini-Lathe-Carriage-Lock-463.html Amadeal lock screw] is in the spares tin as it was too high and fouled the compound slide.''<br />
<br />
===Tailstock locking lever loose===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock - See full image for key to screws]]<br />
* Diagnosed and fixed 10/1/2023 - In the base of the upper section of the tailstock, there are two dog tip set screws that engage with locating grooves in the counter-rotating shafts carrying the eccentric locking cams. They'd backed off, probably due to vibration. They need to be tightened till they bottom out in the groove, making sure they are '''in''' the groove, backed off half a turn so the shafts can turn easily, and locked in place. There's no facility to do so, so reassemble with weak threadlocker. Unfortunately to get to them you have to remove the tailstock base slide, which is held on by the pressure of four adjusting grub screws, which all need backing off, and one socket headed bolt from underneath so full tailstock realignment is required after reassembly, which even for a rough alignment is tedious.<br />
: <s>The tailstock locking lever is loose and can be pulled out on its axis. It works OK when fully pushed home but needs investigating. ''I tightened the grub screw as the lever was coming off its shaft, but the whole shaft pushes/pulls in and out. It works OK fully pushed in, but it seems something that is meant to retain it has failed inside the tailstock base.</s><br />
<br />
===Gear alignment issues===<br />
* Change gear alignment is poor. I've currently got a gapped washer (to clear the key) packing out the A shaft so the gears line up, but this reduces the key's engagement so is problematic due to the high loading if the gears are set up for coarser threads. <s>Also I need to turn down some penny washers to slightly less than the root diameter of the metal 20T pinions, as gear retaining washers.</s> ''The gear retaining washers for A gear and B-C stub shaft are now done, turned down to slightly under 16 mm dia. Spares in the change gear tin. ToDo: The D (leadscrew) washer requires a larger center hole, so make two more with that hole.'' <br />
<br />
===Saddle gibs loose===<br />
* Fixed 11/04/2023: I took the apron off for access (and to clean the carriage handwheel gears), and found the front sheer plate screws were completely loose. I've snugged them up some and set the opposing grub screws and got a lot of the slop out. I've re-checked the front ones, and taken up the slop in the rear ones - Unfortunately it wasn't possible to get carriage movement to have an even 'feel' over its whole travel, and its noticeably tighter near the tailstock. If light hand pressure on the side of the unlocked carriage can cause movement (with the half-nuts open), its time to readjust them again, though it should be possible to move the carriage with a firm push. <s>The saddle gibs (actually the sheer plates) were too loose, to the point that engaging a slightly stiff threading dial could cause it to self-feed, an obvious crash hazard if working near the chuck or a step in the work.</s><br />
<br />
''N.B. the lefthand front opposing grubscrew is short, (fully recessed) and unlike the others does *NOT* have a locking nut as it must clear the traverse pinion. A wrap of PTFE tape provides enough friction to keep it in place, though possibly a bit of nylon fishing line down its hole would be better.''<br />
<br />
===Excessive cross-slide backlash===<br />
* ''Fixed 21/11/2023.'' Originally, back in October 2023, The cross-slide screw had excessive backlash (nearly three turns), which increases the risk of loosing track of the cut depth when cutting steps, and during threading operations. If you ended up off by a turn too far in, a crash would be the most likely outcome.<br />
: The original excessive backlash was traced to loose cross-slide screw nut mountings. The nut has two socket headed cap screws pulling up, one either end, accessible from the top of the cross-slide, which control the tilt of the nut to take up backlash in the nut, and an opposing grub screw pressing down on the center of the nut to make it longitudinally rigid. Snugging up the grub screw reduced the backlash to 10 divisions or so, or 0.25 mm. A year later, the backlash had increased to one turn due to the cross-slide nut mounting screws working loose again.<br />
<br />
: 07/11/2023: I investigated further: It is difficult to get the cross-slide nut aligned correctly as it must be at the same height as the screw which is constrained by the bearing surfaces in the bracket. With the cross-slide almost at the front limit of its travel, I removed the screw and set the nut as level as possible and visually centered in the bore, then re-fitted the bracket and screw, then adjusted the tilt till it turned freely through the backlash. I then tilted it up at the front till some drag was felt to minimise the backlash and tightened the screws to lock it in place balancing them to maintain the same feel as I tightened them. The result was 7 divisions of backlash, acceptable but not great. During normal turning operations, the load on the nut is tension on the front screw and pressure on the grubscrew, so if it slackens again due to vibration from chatter, odds are it will be the rear screw that's loosened.<br />
<br />
: 16/11/2023 - 21/11/2023: The backlash had crept back up to 11 divisions (0.275 mm). We don't have any >14 mm brass stock (or even near that) so I tried making the shim washer out of aluminium. I was shooting for 0.24 mm but due to poor technique got 0.28 mm. No good - locked solid. I lapped it down and tried it till I got it down to 0.20 mm which gave about 3 divisions backlash - good enough, but the screw was too tight due to the shim washer not being bevelled at its outer edge resulting in it cupping in its seat. Filing a bevel round the OD and re-lapping it resulted in a 3 - 4 divisions of backlash. Its a little mushy due to the washer having been kinked removing it, so ideally a new (brass) washer should be made. <br />
<br />
* Further reduction of backlash: https://youtu.be/Wu_tI29JL2Y?t=163 <br />
: Brass tinned with Pb-free solder to form a white metal bearing surface should work at least as well as the bronze used in the video. The shim washer needs to be 10.2mm ID, with a full thickness bevel on a 14 mm OD. It isn't necessary to remove the lead screw from the cross slide, as the washer can be fitted in-situ with only the bracket removed.<br />
<br />
===3 Jaw chuck didn't mount properly===<br />
* Fixed 7/4/2023 by grinding the spindle nose lip. The three jaw chuck can now be installed and removed by hand with no hammering. A test bar in it now has only 2 thou runout (TIR) at the chuck.<br />
: <s>The three jaw chuck and the faceplate aren't seating properly on the spindle nose. Its too tight on the register diameter of the lip. This results in grossly excessive runout, and also makes this chuck and the faceplate a PITA to fit or remove.</s><br />
: ''The spindle nose had been abused with a hammer (before my time) which mushroomed it and may have brinelled its bearings. See '''Excessive Runout''' and '''Spindle bearings''' above.''<br />
<br />
== Manuals, Books and other resources ==<br />
=== Manuals ===<br />
The [https://wiki.richmondmakerlabs.uk/images/a/a3/Lathe_InductionNotes.pdf RML CJ18A Mini-Lathe Induction Notes]. Your mandatory Lathe Induction will cover most of this but its good to be able to refer back to it.<br />
<br />
Official [https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Amadeal CJ18A Manual], or paper copy (less complete) kept on shelf above lathe.<br />
<br />
The [https://www.chesterhobbystore.com/wp-content/uploads/2022/11/Conquest-Super-Lathe.pdf Conquest Super Lathe manual] is considerably better than the Amadeal manual and is for a near-identical machine.<br />
<br />
The [https://littlemachineshop.com/images/gallery/info/minilatheusersguide.pdf Mini Lathe User’s Guide] from LittleMachineShop.com is even more comprehensive, going into its usage in some detail, with a proper TOC, and covers both US and Metric versions of Realbull Mini-lathes. ''The only fly in the ointment is the threading section assumes a US lead screw so change gear selections and threading dial divisions will not be correct for our lathe.''<br />
<br />
[https://www.arceurotrade.co.uk/machineguides/C3-Mini-Lathe-Dismantling-and-Reassembly-Guide.pdf Sieg C3 Mini-lathe Dismantling and Reassembly Guide] "A picture story book to help you dismantle and reassemble your Sieg C3 Mini-Lathe" ''It is similar enough to ours to serve as a maintenance guide, except for the electronics, spindle drive and other headstock innards.<br />
<br />
The motor controller is a clone of a [https://acim.nidec.com/drives/kbelectronics/-/media/kbelectronics/documents/dc-drives/manuals/kbic_manual.ashx?la=en KBIC® SCR DC Motor Speed Control]<br />
<br />
=== Books ===<br />
'''Metal Turning on the Lathe''', by David A Clark, Crowood Metalworking Guides, ISBN-13: 978-1847975232 [https://www.amazon.co.uk/gp/product/B00E78RKIG Kindle Edition (£8.99)]. ''A 'free' epub can be googled for, *NOT* linked here due to dubious legality.''<br />
<br />
'''[https://archive.org/details/03screwcuttinginthelathe Screwcutting In The Lathe]''', by Martin Cleeve (a pen-name of Kenneth C Hart), Workshop Practice series #3, ISBN-13: 9780852428382<br />
<br />
'''[https://archive.org/details/15workholdinginthelathe Workholding in the Lathe]''', by 'Tubal Cain' (a pen-name of Tom Walsh), Workshop Practice series #15, Argus Books, ISBN-10: 0852429088<br />
<br />
'''[https://archive.org/details/20metalworkandmachininghintsandtips Metalwork and Machining Hints and Tips]''', by Ian Bradley, Workshop Practice series #20, ISBN-13: 9780852429471<br />
<br />
'''[https://archive.org/details/38toolandcuttersharpening Tool and Cutter Sharpening]''', by Harold Hall, Workshop Practice series #38, ISBN-13: 9781854862419<br />
<br />
'''[https://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpaperT204.pdf Cutting Fluids]''', by EC Bingham, NIST Tech. Paper No. 204, 1921<br />
<br />
=== WWW resources ===<br />
==== Mini-lathe Specific ====<br />
There's a *LOT* of mini-lathe info online. Notable sites include:<br />
* http://www.mini-lathe.com/ - A major Realbull/Sieg mini-lathe resource.<br />
* http://mikesworkshop.weebly.com/lathe-modifications.html - many mods including carriage DRO autostop, and variable speed leadscrew motor drive, cross-slide motor drive, etc. He also has a page with a bunch of accessories, toolholders etc. - http://mikesworkshop.weebly.com/lathe-accessories-and-tooling.html<br />
* http://andysmachines.weebly.com/variable-speed-controls.html - Scroll down to the 'UPDATE' section for the schematic of a very similar SCR speed control board. It also has the schematic for an earlier version of the Auxiliary Control Board (aka: 'Filter' board).<br />
<br />
==== Forums ====<br />
''with publicly accessible archives''<br />
* https://groups.io/g/7x12MiniLathe - Mini-lathe specific, active<br />
* https://www.hobby-machinist.com/forums/mini-lathe-mini-mill-information.220/ - active<br />
==== Youtube Playlists & Videos ====<br />
* Blondihacks: [https://www.youtube.com/playlist?list=PLY67-4BrEae9Ad91LPRIhcLJM9fO-HJyN Lathe Skills] (playlist) - "This is an educational series to help you learn to use your metal lathe. Watch them in order for best results! Satisfaction not guaranteed, especially if you're a cranky sort of person."<br />
* Frank Hoose (Minilathe.com) has a couple of relevant Youtube playlists:<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn7ON0jGM5UbM-KZDT56MOIp Mini Lathe Operations]<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn4nGRZaVq3wTOlvZNOmdAZ2 Mini Lathe Overview]<br />
<br />
==== General Machining ====<br />
* https://www.machiningdoctor.com/ - "THE #1 MACHINING TECHNICAL HUB"<br />
<br />
==Projects==<br />
[[File:VESA mount.jpg|thumb|Machined VESA mounting plate (left) and plate from Dell monitor stand it must match (right). The translucent washer shows the size of the original center hole.]]<br />
* My first faceplate project was boring out the center hole in a VESA mounting plate to adapt it to fit onto a surplus Dell 1708FP monitor stand. The part was centered using the tailstock dead center engaging with its original center hole. I clamped the part with studs and penny washers on the driving side of two opposite corners, with cap screws in the next slot round to trap the corners under the clamping washers, then withdrew the tailstock and dead center. After machining out the bore, I used the tip of the tool, rotating the chuck by hand, to scribe a circle for laying out the bolt holes. I finished off laying out and drilling the bolt and locating holes by hand at home, fitted it to the stand, and mounted the 2nd hand LG 24" widescreen monitor.<br />
<br />
* Another ultimately unsuccessful project was fly cutting aluminum flat bar to thickness to make custom shims for the set of carbide insert tools, for the four way toolpost. The 8 mm shank tools need ~2.5 mm shim stacks, and the 6 mm shank tools need ~4.5 mm shim stacks. Ideally I'd machine single shims, but the only stock I've got handy cleans up to only 3.2mm, and some fine shimming may be needed to fine-tune the tool height.<br />
<br />
: After sorting out the clamps so they were no longer twisting the aluminum flat bar stock, and switching to the short 45° turning SCMT06204 insert tool in the four way toolpost, to improve rigidity and get a well controlled tip radius, the finish was much improved. I'm still having problems getting an even thickness and am getting approx. 0.05mm variation, I suspect due to the aluminium bar stock distorting due to internal stresses as its surface is cut away. ''ToDo: try supergluing the stock to the faceplate before clamping to further reduce chatter and stop the warping.''<br />
: Looking back on this project a year later, its fairly obvious that the thickness variation was probably due to faceplate surface runout due to the damaged spindle nose.<br />
<br />
* Raphael has been working on a steel rocket nozzle with some assistance from myself. We have set up the rough cut chunk of ~ 50mm steel bar, faced both ends (to 50mm length) and turned the OD to 49mm to clean it up. Its going to need through drilling, probably some boring, and quite a bit of detail work on the OD. It will then need to be transferred to a jig in the drill press vice to allow a pattern of angled traverse holes to be drilled with acceptable accuracy.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_Lathe_Notes&diff=17600Ian M's Lathe Notes2023-12-15T11:32:07Z<p>IanM: /* Spindle bearings */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br />
<br />
''Currently these notes are semi-organized and non-authoritative. As I become more experienced with the RML CJ18A mini-lathe, I'm cleaning up, extending and reorganising them. Some lathe operating experience is assumed. If in doubt, '''*ASK*''' me, Andy H<sup>*</sup> , Jonathan H or another experienced minilathe operator!<br />
<br />
''* Andy H should be asked (for an authoritative answer) any questions involving RML usage policies or acquiring tooling or materials through RML.''<br />
<br />
== The Lathe ==<br />
Our Facilities page [[Facilities#Lathe|has]]:<br />
<blockquote><br />
'''Lathe'''<br />
[[File: Lathe2.jpg |200px|right | Lathe]]<br />
In the kitchen. <br />
<br />
Marked as a CJ18A Mini-Lathe from [[https://www.amadeal.co.uk/acatalog/CJ18A-Mini-Lathe-7x14-Machine-100mm-3jaw-Metric-With-Metal-Gears-AMA_LA_CJ18_M_3_MGRB.html Amadeal]]<br />
[[https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Manual]] <br />
<br />
[[Media:Lathe InductionNotes.pdf| Induction Document]]<br />
<br />
Possible upgrades:<br />
*https://www.youtube.com/watch?v=GwT-JQLbNPA<br />
<br />
''Please do not use the lathe until you have received induction'' <br />
<br clear=all><br />
</blockquote><br />
Its a Chinese import 7x14 mini-lathe. The 7x14 refers to the maximum diameter and length of work, in inches and is only a theoretical measure of the working envelope as you loose length to the chuck + any tailstock tooling, and the diameter is over the bed, not the cross-slide. See actual specifications below. <br />
<br />
Most if not all Chinese 7x10 to 7x16 mini-lathes seem to be remarkably similar (not uncommon with Chinese products due to [https://www.bunniestudios.com/blog/?p=284 Shanzhai (山寨)] )<br />
and the OEM of our Amadeal CJ18A Mini-Lathe was probably [https://www.made-in-china.com/showroom/cheap-lathe Yangzhou Realbull Machinery Co. Ltd]. Very similar lathes are also made by [https://www.siegind.com/lathe-machine.html Sieg], but their lathes tend to be slightly less sophisticated than the equivalent Realbull models.<br />
<br />
''N.B. Many Sieg parts are known to have slight but critical differences from Realbull parts, so '''DON'T''' order Sieg spares for a Realbull lathe!<br />
<br />
== Key Specifications ==<br />
Amadeal says the CJ18A Mini-Lathe is a 7x14 model with:<br />
<blockquote><br />
* Power 550 W<br />
* Distance between centres : 350 mm<br />
* Swing Over Bed: 180 mm<br />
* Swing Over Cross Slide: 110 mm<br />
* Taper: MT3<br />
* Tailstock Taper: MT2<br />
* Chuck diameter: 100 mm<br />
* Spindle Speed: 50 - 2500 rpm ''(with digital readout)''<br />
* Spindle Bore: 20 mm<br />
* Cross slide Travel: 65 mm<br />
* Range of Metric Threads: 0.5 - 2.5mm.<br />
</blockquote><br />
* The lead screw is metric, pitch 1.5 mm.<br />
* The spindle center is 90.6 mm above the flat of the bed (measured).<br />
<br />
Even though the compound and cross slide handwheels appear to be calibrated in thousandths of an inch, as ours is a metric machine, they only approximate that. One turn of a slide handwheel is 1mm advance, and they have 40 divisions, so each division is 0.025 mm, (approx. 0.984 [https://en.wikipedia.org/wiki/Thousandth_of_an_inch thou]). Similarly, the tailstock quill advances 1.25 mm per handwheel turn, which has 50 division dial, giving the same 0.025 mm divisions, but only 4 turns per 5 mm. The carriage handwheel is awkward - it moves approx. 19.2 mm per turn, and doesn't have a dial scale.<br />
<br />
== Notable Accessories ==<br />
We have:<br />
* [https://www.amadeal.co.uk/acatalog/160mm-Face-Plate-for-the-4-Mini-lathe-AMA_AC_CJ18A_FP160RB.html#SID=129 160 mm (6 1/4") Faceplate]<br />
* 100 mm (4") three jaw self-centering chuck (OEM standard) 22.5mm bore, with inside and outside jaw sets<br />
* 100 mm (4") four jaw (independent) chuck with reversible jaws (8 TPI screws)<br />
* Tailstock drill chuck (max. 13 mm dia.)<br />
* Live center for tailstock (+ OEM fixed center) <br />
* Four way Tool Post (OEM Standard)<br />
* [https://www.amadeal.co.uk/acatalog/Quick_Change_Tool_Post_for_the_mini-lathe.html Quick Change Tool Post] + 3 tool holders<br />
* [https://www.amadeal.co.uk/acatalog/Fixed-Steady-for-Mini-Lathes-AMA_AC_CJ18A_FSRB.html#SID=145 Fixed Steady Rest]<br />
* [https://www.amadeal.co.uk/acatalog/Travelling-Rest-for-Mini-Lathes-AMA_AC_CJ18_TSRB.html#SID=144 Travelling Steady Rest]<br />
<br />
''You'll find all of the above on the shelf above the lathe, with the accessories in the wooden box, apart from the steadies, which live next to it. Change gears, spare parts, and most cutting tool tips/blanks are in labelled white rectangular tins behind the lathe.''<br />
=== Measuring Tools ===<br />
We have:<br />
* Various dial indicators - the one with the adjustable magnetic base stand is the most convenient for most lathe setup work.<br />
* 25mm micrometer (in little grey case)<br />
* Grey case containing set of measurement tools including dial calipers, micrometer, steel rule (metric & inch), engineers square, and a fish-tail gauge<br />
<br />
''We currently lack''<br />
* ''A tool height setting gauge''<br />
<br />
=== Hand Tools ===<br />
Some common tools needed for normal use are kept with the lathe, in or attached to the wooden accessories box:<br />
* 2 mm Allen key - adjusting cross-slide and compound gibs<br />
* 4 mm Allen key - quick change toolholder tool clamping screws + height adjust, tightening dials<br />
* 5 mm Allen key - four way toolpost tool clamping screws, engaging/disengaging threading indicator<br />
* 6 mm Allen key - locking/unlocking quick change toolholder<br />
* 8 mm spanner - locking carriage when 8 mm socket can't be used, locking gib adjuster nuts <br />
* 13 mm spanner - changing chucks, locking steady rest jaws<br />
* Very long needle nose pliers - for grabbing swarf safely, holding one end of emery cloth safely so you can keep your fingers away from the jaws, and extricating small objects from awkward places.<br />
<br />
== Change Gears ==<br />
[[File:BC puller 1.jpg|thumb|Custom puller for B-C stub shaft]] [[File:BC puller 2.jpg|thumb|Pulling the B-C stub shaft]]<br />
See "Conquest Super Lathe" manual ([[#Manuals|below]]), section '''4.7 Change Gears''', PDF pages 28-29, but see below for mesh adjustment. The LittleMachineShop.com "Mini Lathe User’s Guide" (also below) section '''Threading''' gives a far better explanation, with pictures and diagrams, but its for a lathe with a US 1/16 inch pitch leadscrew, not a metric 1.5 mm pitch one like ours, so you *MUST* ignore all the tables in that section, replacing them with metric mini-lathe (with 1.5 mm pitch leadscrew) equivalents. <br />
<br />
We have the following tooth count gears: 20,20, 30, 35, 40,40, 45, 50,50, 60,60, 80,80<br />
which consist of the OEM power feed gears + the metric change gear set. Apart from the metal 20 tooth pinions, they are all plastic, probably Delrin if the molded in 'POM' marking can be trusted, but possibly plain Nylon 6, and are metric Module 1.<br />
<br />
If we wanted to add the capability to cut US/Imperial threads we'd need to buy additional 55, 57 and 65 tooth gears, and possibly a 21 tooth metal pinion.<br />
<br />
CGTK's [https://www.cgtk.co.uk/metalwork/calculators/changegears/minilathe?gears1=20,20,30,35,40,40,45&gears2=50,50,60,60,80,80&gears3= Change Gear Calculator] ''(link preloaded with our gear list)'' is useful if you don't want to calculate the ratios from first principles. Not all suggested combos will physically fit.<br />
<br />
* Take care *NOT* to loose the keys in the A and D shaft keyways - turn each shaft till the keyway is up before removing the gear. <br />
* The B and C gears are coupled by a hollow stub shaft (with an integral key), which is so tight in the gears it has to be pressed or driven out - I've made a puller just for this task, kept in the change gears tin.<br />
* The center of the B-C stub shaft *MUST* be lubricated where it runs on its pin on the change gear banjo bracket, with grease or heavy oil. ''Seizure of the stub shaft due to running dry is a frequent cause of catastrophic mini-lathe geartrain failures!''<br />
* Don't get oil on the change gears as it can cause plastic gears to crack. Only PTFE drylube or plastic compatible white grease should be used on their teeth. <br />
* Adjust the B-C pin position in the straight slot first to set the C to D gear mesh, tighten its nut, then swing the whole banjo about the D shaft boss to set the A to B mesh, and finally tighten the banjo clamping nut.<br />
* Check both gear meshes have running clearance by turning the chuck by hand enough to complete one full turn of the leadscrew, and by attempting to turn the intermediate gear(s) to assess backlash, If excessive resistance is felt or if there's significant backlash, readjust the gears. If you have difficulty judging the mesh, a strip of 80 gsm copier paper (approx. 0.1 mm thick) wound into the meshing teeth before tightening the stud or banjo will give appropriate clearance once removed. Once setup, check the gears run quietly under power.<br />
* If the sum of the tooth counts C+D is the same as for the ones you just removed and they were correctly meshed, you don't need to move the stub shaft pin. If A+B is <u>also</u> the same, you don't need to move the banjo. e.g. If it was set up for 16:1 reduction power feed, 1 mm (40:60 - 50:50) for M6 and 1.5 mm (e.g. 40:60:40) for M10 pitches can thus be achieved by only swapping gears. <br />
<br />
''The change gears, puller, etc. and a box spanner for the banjo nut are kept in a white rectangular tin behind the lathe.''<br />
<br />
=== Power Feed ===<br />
When used for turning with power feed, the change gears should be set for a 16:1 reduction (A:20 : B:80 - C:20 : D:80) using the pair of small metal 20 tooth pinions and the 80 tooth plastic gears (largest in set), for a feed of 0.09375 mm per turn (1.5 mm/16). Unless continuing your threading project the next session, please re-fit the 16:1 power feed set after threading so the power feed is ready for use. <br />
<br />
* *ALWAYS* leave the feed direction selector lever in its neutral (no feed) position, and the half-nuts open after use.<br />
* *ALWAYS* check the carriage lock is disengaged before engaging power feed. Unlock the carriage after use. <br />
<br />
=== Threading Dial ===<br />
The threading dial is an aid to re-engaging the half-nuts at the right moment so the tool will retrace its previous path cutting deeper, rather than offsetting axially some fraction of the thread pitch and ruining your work. Its based on the concept of the lowest integer multiples of the leadscrew and thread ''(being cut)'' pitches that exactly match, but for mechanical simplicity it only covers certain selected multiples of the leadscrew pitch.<br />
<br />
We have a choice of three pinion gears:<br />
{| class=wikitable<br />
|+ Threading dial Pinion Gears<br />
|-<br />
! Teeth !! Colour Dot !! Usable lines !! OD gear !! Dist. per turn<br />
|-<br />
| 14 || Red || 1,7 || 7.51 mm || 21 mm<br />
|-<br />
| 15 || Orange || 1,5,9 || 8.05 mm || 22.5 mm<br />
|-<br />
| 16 || Green || 1,4,7,10 || 8.37 mm || 24 mm (2 mm/div)<br />
|}<br />
They are now colour coded, with a paint dot on the gear end face ''(the only non-wear surface)''. The 16 tooth one is normally left on the lathe, but disengaged when not threading to minimise wear on the lead screw. The others are kept in the Change Gear tin.<br />
<br />
There's a threading dial 'pickup' calculator here: https://www.cgtk.co.uk/metalwork/calculators/threaddialindicator <br />
<br />
Initially select ''Lathe:'' '''Custom''', and enter the following below:<br />
* ''Units:'' '''Metric'''<br />
* ''Lead Screw Pitch (mm):'' '''1.5'''<br />
* ''Thread Dial Indicator Gear Teeth:'' '''16,15,14''' <br />
* ''Lines on Thread Dial Indicator:'' '''12''' <br />
* ''Line Marking:'' '''Every Line Numbered'''<br />
Note the teeth list is entered in reverse order so the resulting table highlights any required pinion changes.<br />
<br />
N.B. The dial is only friction clamped to the pinion by its center screw. If you have any reason to suspect it may not be properly aligned: <br />
# With the power off and the carriage unlocked, engage the feed direction lever upwards. You'll probably need to turn the chuck by hand to get it to engage.<br />
# If the threading indicator isn't already engaged, loosen the threading dial support block bolt, pivot the block to engage the pinion with the leadscrew and retighten the bolt.<br />
# Engage the half nuts, again turning the chuck by hand till they drop in. <br />
# Turn the chuck a couple of turns, top towards you to take up any backlash, then lock the carriage, taking care not to push it left while locking it.<br />
# Loosen the screw securing the dial to the pinion.<br />
# Align the '1' line of the dial with the index line, by rotating the dial clockwise, then retighten the screw.<br />
# Don't forget to disengage half-nuts and unlock the carriage!<br />
<br />
The above instructions should result in the half-nuts engaging cleanly when exactly on any valid line when threading towards the headstock. If it is required to thread away from the headstock, there will be a slight offset from the line due to backlash between the spindle gear and leadscrew, so engage slightly early.<br />
<br />
Changing the pinion:<br />
# Loosen the threading dial support block bolt and disengage from the leadscrew.<br />
# Undo dial center screw, and remove it and the dial, dropping the old pinion out the bottom.<br />
# Oil the shaft of the new pinion with a drop of light oil and insert it from below, gear end down.<br />
# Refit dial and screw.<br />
# Check the dial and pinion turn freely with minimal resistance.<br />
# Align as above.<br />
<br />
== Tailstock and Steadies ==<br />
These are mostly used to support long work ''(long with respect to its diameter)'' to improve rigidity, increasing accuracy and reducing chatter. The Tailstock quill is also used with a drill chuck for drilling.<br />
=== Tailstock ===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock base]]<br />
The tailstock can be offset to turn shallow tapers between centers. We don't currently have the accessories to turn between centers, namely <s>a MT3 dead center for the spindle, or</s> any drive dogs for the work. Also realigning the tailstock after turning a taper can be a PITA. The photo shows the tailstock adjusting screw locations ''(C - Lateral, and D - Skew)'' and the block on the baseplate they engage with. Adjustments can only take effect when the tailstock locking lever is eased to take the pressure off the baseplate. As we don't have a MT3 center, one has to turn a fresh point on a test workpiece for a rough tailstock alignment reference. Fine alignment, to avoid inadvertent taper turning, can be done by mounting a long precision ground bar between the chuck (or preferably a center in the spindle), and a dead center in the tailstock and sweeping it with a dial indicator on the carriage. Finally a test cut should be taken at either end of a bar between centers, and the diameters checked with a micrometer. Assuming the bed has previously been properly levelled and shimmed to take out twist ''(not the case at RML as we don't have it bolted down)'', any remaining difference in diameter will be double the tailstock offset, smaller at the tailstock being offset towards the front. Fine adjustment cant be achieved by jacking with the screws, its best to ease the adjusting screws, bump the tailstock into alignment then take up the screws again, checking the alignment is maintained when the tailstock is unlocked and relocked. There is no vertical adjustment, though shims can be added between the tailstock and its base.<br />
<br />
==== Tailstock Quill ====<br />
There is a metric/imperial scale on the top of the quill, read against the end of the tailstock, for depth measurement when drilling. The tailstock quill has a 1.25 mm pitch thread and a 50 division dial. Each division is therefore 0.025 mm, and it only takes 4 full turns of the handwheel to move the quill 5 mm. <br />
<br />
To eject MT2 taper tooling and centers from the tailstock, wind the quill all the way in.<br />
<br />
N.B. The quill anti-rotation pin (dog-tip setscrew + locking nut in top of tailstock near to the quill lock) is only M5. It will sheer if a large diameter drill jams in the work. Please back it out clear of its keyway if using large drills, and use alternative methods of preventing chuck rotation. To re-engage it, crank the quill out till you can see the keyway, align it with the screw and screw in the screw till it gently bottoms out, then back it off a quarter turn. Try twisting the quill to check its properly engaged, then tighten the locking nut gently to hold the screw in position clear of the bottom of the keyway.<br />
<br />
=== Steady Rests ===<br />
We have two, both with brass tips that must be kept lubricated during use.<br />
<br />
The fixed steady mounts on the ways, and is most useful when turning longer work that wont fit through the spindle bore. Adjustment is critical, and the surface the tips run on must be smooth and concentric, as any misalignment that forces the work off center will result in the work wobbling in the chuck, marring it, with a high risk of it becoming un-chucked, which can be dangerous at speed.<br />
<br />
The travelling steady mounts to the headstock side of the carriage to locally resist the deflection of thin long work, due to the cutting forces. It only has two tips, to resist climb, and deflection away from the tool, and requires readjustment after every cutting pass.<br />
<br />
== Tooling and Tool Holders ==<br />
'''Key dimensional data:'''<br />
* The quick change holders accept up to 10 mm shank tools. <br />
* The four way toolpost has 50 mm long sides, a seat width of 15 mm and can clamp tools of up to 5/8" (15.875 mm) shank ''(check this)'', but the slot base is only 10.4 mm below the spindle center so cannot be used with >10 mm shank tooling unless it has a dropped tip. Large tooling with a centered tip is also problematic as you run out of height above the shank when trying to shim to match the spindle center height. <br />
<br />
===Quick Change Toolpost===<br />
I've got the quick change toolpost and toolholders setup for mostly easy use. The three toolholders came with cantilever height setting arms which historically haven't been installed as the supplied fixing screws were too short. That's all now sorted out and a HSS RH turning tool and a HSS hand-ground grooving/parting-off tool are now mounted in two of the holders and set to height. The third is kept free for other tools. <br />
<br />
The quick change toolpost has been modified with a spring to press the dovetail clamp outwards and help stop it twisting or flopping about to ease toolholder fitting and removal. The dovetail clamp (socket headed screw on toolpost side opposite dovetail) feels a bit stiffer than before, but will take less than half a turn to go from open (with the toolholder lifting out or dropping in easily) to fully clamped. As there is so much less clearance in the open position you should no longer need to wiggle the toolholder while clamping it to get a consistent height. If the dovetail clamp ever gets misaligned, twist it straight by eye, slacken off a bit further than usual to get a toolholder on, clamp it to align the dovetail then release, reseat the toolholder and re-clamp to ensure its at its preset height. You cant adjust the height by 'jacking' with the height screw due to its offset leverage. Instead, back off the height screw and hold the toolholder at the desired height while locking the dovetail clamp, then adjust the height screw (and locking nut) to hold it there, then check it doesnt change height significantly when you unclamp and reclamp the dovetail. <br />
<br />
Unfortunately the OEM height setting screws foul the toolpost locking nut handle. Currently, if you need to swap toolposts you will have to first remove the quick-change tool holder from the post. There is enough nut handle swing to allow the quick change toolpost to be unclamped and rotated to fine set the tool angle without removing the toolholder. It also seems the mating surfaces may be slightly out of square, as if you rotate the toolpost 90° or 180°, the nut swing may be insufficient to re-clamp it without removing the toolholder to do so. Add a M10 washer under the locking nut if the handle ends up pointing in an undesirable direction! A thin M10 washer is kept with the toolpost collar for this purpose, and will shift the handle position by about a third of a turn. <br />
<br />
''ToDo: Make a taller nut of a similar pattern, to clear the height setting screws.''<br />
<br />
===Four Way Toolpost===<br />
The OEM four way toolpost is significantly more rigid than the quick change toolpost + holders because it has fewer and thicker parts and less overhang. Therefore the four way toolpost should be used when using carbide tooling. It requires shimming under the tool to set the tip height to the spindle center height - see below. The tool shanks are mostly significantly less than 15 mm wide, so need to be centered under its clamping screws, tempting as it is push the shank in for full side contact with the toolpost. If possible clamp the shank with all three screws not just two.<br />
<br />
==== Shimming ====<br />
We typically only mount up to two tools, and want maximum rigidity, so use 50 mm x 15 mm shims, (the full seat area), preferably with deburred edges and radiused corners so they aren't a hazard to the operator.<br />
<br />
We have pre-cut and marked shims of the following thicknesses: <br />
* 1x 3.23 mm, 2.42 mm, 1.56 mm, 0.32 mm, and 0.25 mm<br />
* 2x 1.00 mm, 0.77 mm, 0.12 mm, 0.11 mm, 0.10 mm and 0.05 mm<br />
* 4x 0.53 mm<br />
<br />
Our shims are mostly found materials (hence the awkward thicknesses) and are mostly a mixture of aluminium and steel, with a couple of GRP ones. The toolpost seat '''<u>must be absolutely clean</u>''' to avoid embedding debris in the aluminium or GRP shims, to get a consistent height and avoid tilting the tool - wipe it every time you change a tool! Put the thin shims at the bottom of the stack to avoid the tool shank edges creasing them. Shims are kept in a little yellow plastic box with a clear lid, near the carbide tools case.<br />
<br />
I made a tool height setting gauge (T shaped black acrylic with steps in its sides) which can be used to check the tool tip height matches the spindle center height using either the flat of the ways or the saddle as a reference. The tool tip should just fit under the lip of the appropriate step, with the T arms across the ways flats or on the saddle. It is kept in the box with the carbide insert tools.<br />
<br />
''ToDo:'' <br />
<br />
* ''Cut more shims neatly, mark them with their thickness.''<br />
* <s>''Do test cuts and start noting shim stack-ups for various tools.''</s><br />
* ''Organise shim storage!''<br />
<br />
=== HSS Tools ===<br />
[[File:Tool Bit Geometry.jpeg|thumb|Single point cutting tool geometry]]<br />
Our HSS tools are made from 8 mm square bar stock, hand-ground to tip profile in-house. See LittleMachineShop's [https://littlemachineshop.com/images/gallery/instructions/grindingtoolbits.pdf Grinding Tool Bits] notes. <br />
<br />
I've installed our usual HSS LH turning and parting off tools in two of the quick change holders and set the heights correctly. There are a couple of other HSS tools or tool blanks knocking about. Taking heavy cuts turning steel (even with good cutting oil) blunts HSS tools fairly quickly, which are time-consuming to re-sharpen nicely without a dedicated tool & cutter grinder with appropriate jigs. Its worth noting that the usual 'speeds & feeds' tables are commonly based on surface speeds expected to give a half hour (active cutting) tool life before resharpening.<br />
<br />
I touched up the LH turning tool by lapping on wet & dry (silicon carbide) paper on glass (Aka: [https://en.wikipedia.org/wiki/Scary_sharp 'Scary Sharp']) working upwards through the grits 200, 400, 600 and finally 1000, initially 'bluing' the surfaces to be lapped with a marker pen to see which areas needed taking down more. The end of the tool was significantly uneven so I touched that up freehand on the bench grinder to flatten it when it became apparent that 200 grit lapping wasn't cutting where it needed to. There was an existing micro-bevel on the leading side, which I kept. Finally I 'dubbed' the leading corner vertical edge on the 1000 grit to give it a very slight nose radius. A test cut on brass gave a very nice finish when turning.<br />
<br />
''Ian B has purchased some spare 8mm HSS tool blanks - talk to a lathe trainer if your proposed lathe work needs custom ground HSS tooling.'''<br />
<br />
=== Brazed Tungsten Carbide Tools ===<br />
Somewhat of a half-way house between hand ground HSS tooling and insert tooling with the disadvantages of both and some more besides - e.g. they are much harder to sharpen. So why do we bother? Some tool geometries would be awkward and tedious to hand grind, and Chinese import brazed carbide tooling is about half the price of similar HSS tooling, and far more readily available. Also, for space constrained tooling like boring bars, if you want carbide, for insert tooling, the size of the insert and its clamping seriously limits the minimum hole diameter you can work in. I have purchased a set of 3/8" shank brazed carbide tipped boring bars, but we currently cant sharpen them, due to lack of a diamond grinding wheel. <br />
<br />
=== Tungsten Carbide Insert Tools===<br />
Decoding ISO insert tooling part numbers: https://www.cutwel.co.uk/blog/learn-the-turning-tool-iso-code-system<br />
[[File:Carbide set.jpg|800px|thumb|left|Our set of Tungsten carbide insert lathe tools (before the new inserts were fitted)]]<br />
<br />
{| class=wikitable<br />
|+ Tools, left to right, (+ last across top):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| SSKCR0610H06 || 75° through boring || SCMT06204 || Long || 6 || 6.34 || ''4.33''<br />
|-<br />
| SSSCR0610H06 || 45° deep facing, internal chamfering || SCMT06204 || Long || 6 || 6.13 || ''4.58''<br />
|-<br />
| SWUCR0610H05 || 93° boring, deep facing || WCMT050308 || Long || 6 || 6.22 || ''4.48''<br />
|-<br />
| SWGCR0810E05 || 90° RH turning & facing || WCMT050308 || Short || 8 || 8.25 || '''2.45'''<br />
|-<br />
| SSSCR0610E06 || 45° turning, chamfering || SCMT06204 || Short || 8 || 8.75 || ''1.93''<br />
|-<br />
| SSBCR0610E06 || 75° RH turning, chamfering || SCMT06204 || Short || 8 || 8.72 || ''1.98''<br />
|-<br />
| LW0810R-04 || 60° external threading || JCL15-120 || Short || 8 || 7.44 * || ''3.28''<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || 8.23 || ''2.5 ?''<br />
|-<br />
| LN0813R-04 || 60° internal threading || JCL15-120 || Long || 7.95 || 7.44 * || ''3.28''<br />
|}<br />
<br />
{| class=wikitable<br />
|+ More Tools, (loose in tin):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || ~8.5 (not in use) ||<br />
|-<br />
| [https://www.glanze.co.uk/product/glanze-12-mm-60-degree-metric-internal-threading-tool/ Glanse SIR0012K11] || 60° internal threading bar || 11IRA60 || Long || 12 dia || ??? || ???<br />
|}<br />
''Shim stack heights in bold are tested, in italic are only calculated.'' ''Tip heights marked * are with new JCL15-120I inserts. The single remaining plain JCL15-120 insert has a slightly higher tip height.''<br />
<br />
Carbide tooling typically requires two to three times more speed than HSS and at least a couple of 'thou' depth of cut for best results.<br />
<br />
Chatter can rapidly kill carbide tooling by chipping the cutting edge. To improve rigidity and reduce the risk of chatter, the cross-slide and compound gib screws need to be well adjusted so there is minimal play in the slides, tool stick-out should be minimised, the four way toolpost should be kept over the cross-slide, and the work should be kept close to the chuck (or otherwise supported by tailstock or steady rest) to avoid excessive deflection.<br />
<br />
Thermal shock is almost instant death to carbide, and when dry cutting the insert tip can run very hot, so do not add extra cutting fluid manually during the cut. Pre-apply what you need, evenly, before starting the cut.<br />
<br />
Parting off or facing to center is high risk - if the tool tip is even slightly below center or if tool or work deflection takes it below center, the work will tend to climb over the tool tip as the cut approaches center, breaking the insert. To avoid this, the tool should be shimmed slightly above center, sufficient to allow for work and tool deflection, and unless very close to the chuck, a steady should be used. Its often preferable to part to a couple of mm dia. remaining then stop and saw through the remainder. Parting off hollow parts is much lower risk.<br />
<br />
Further investigation of the Tungsten carbide insert tool height situation is not encouraging - the so-called 'set' in question does not have a consistent tip height ''(see above table)''! In a real set, the insert seats *should* be machined allowing for the insert thickness to bring all the cutting edges to the same height with respect to the shank underside. However if you place them tip to tip on a table its easy to see there is considerable height variation, so they need to be individually shimmed (or at best, one machined shim will only be right for two or three tools). At this time we don't have dedicated shim stacks for each tool.<br />
<br />
A 2.42 mm thick shim brings the SWGCR0810E05 90° RH turning & facing tool almost exactly to center height, and good results were obtained turning 1" steel pipe. However facing 50mm steel bar stock to center found it to be slightly low, leaving a fractionally under 0.05 mm 'pip' so it needs another 0.03 mm to bring it fractionally above center. Fractionally too high is generally preferable to fractionally too low, due to tool deflection, so adding an 0.05 mm shim to the stack should produce optimum results.<br />
<br />
==== Inserts ====<br />
Ian B has purchased the spare inserts we needed in sets of five. He even was able to get the CK3 parting-off inserts which had been difficult to source!<br />
<br />
Inserts used in above tool set:<br />
* 3x SCMT06204 (square, indexable) https://www.rdgtools.co.uk/acatalog/SCMT-06-Carbide-Insert.html<br />
* 2x WCMT050308 (triangular, indexable) https://www.rdgtools.co.uk/acatalog/WCMT-05-T3-08-5XTIP-8813.html<br />
* 2x JCL15-120 (60 deg threading point) https://www.rdgtools.co.uk/acatalog/X5-JCL-15-120L-THREADING-TIPS-60-DEGREE--X5-TIP---23455.html<br />
* CK3 (parting off) https://www.rdgtools.co.uk/acatalog/CK3-CARBIDE-TIPS---PARTING--BOX-OF-5PCS--9437.html<br />
<br />
Inserts used in other tools:<br />
* 1x CK3 (as above) also missing from spare parting off tool<br />
* 1x 11IRA60 in Glanse threading bar + 1x spare<br />
<br />
=== Drills ===<br />
Various sizes of center drills are kept in a plastic bag next to the wooden accessories tray. There's also a small box of 2.5 mm center drills.<br />
<br />
We have a set of 11 TiN coated HSS drill bits from 1.5 to 8 mm, (in a cylindrical plastic index box) for tailstock drilling of brass, aluminium and non-abrasive plastics. To keep them sharp enough for the precision work we expect from the lathe, please don't use them for steel or reinforced plastics, and don't borrow them for non-lathe use. Metric and US [https://littlemachineshop.com/reference/numberdrillsize.php numbered]/[https://littlemachineshop.com/reference/letterdrillsize.php lettered] general use HSS drill bits are kept in two red metal index boxes next to the drill press.<br />
<br />
== Using the Lathe ==<br />
=== General ===<br />
A cutting speed chart for HSS tooling, published by Model Engineer magazine can be found [https://www.model-engineer.co.uk/sites/7/documents/cutting%20speed%20chart.pdf [here<nowiki>]</nowiki>]. The second row is the target feed rate and the rest of the chart, apart from the diameter column is RPM.<br />
<br />
For carbide tooling cutting iron and steels, recommended speeds are generally three times higher than for HSS, but the CJ18A 2500 RPM max. spindle speed (in high gear) means you can only reach the optimum speed range for over 15 mm dia work. For small diameter work, HSS tooling may well be a better choice.<br />
<br />
An online metric speeds calculator is here: https://www.cgtk.co.uk/metalwork/calculators/cuttingspeeds <br />
<br />
How to do the maths to calculate speeds and feeds: https://www.cutwel.co.uk/blog/speeds-feeds-made-easy<br />
<br />
Making dimensioned parts is primarily done by touching off the tool tip on a reference surface (with the lathe stopped, turning the chuck by hand), zeroing the handwheel dial, then manually counting turns and divisions. When backing off the tool its best to do so by exactly one whole turn so you don't forget the previous dial position. Stopping and measuring the work before taking the final cuts is essential if high accuracy is required. ''I've changed out the dial setscrews for flat tip ones with a tiny slug of solder under them so the dials are now friction fit on their shafts. i.e. if you hold the handle firmly taking up the backlash in the direction of cut, you can zero the dial just by grabbing and twisting it.''<br />
<br />
Carriage movement is less easy to measure as the handwheel is uncalibrated and advances an awkward bit over 19.2 mm per turn. Your options here when shoulders or other features must be exactly positioned are, in order of increasing accuracy: <br />
* Use measuring instruments, scribe the work at the desired length then work to the scribed line. Its often convenient to black the work with a permanent marker, then scribe with the tool tip, turning the chuck by hand.<br />
* for short distances, lock the carriage and use the compound, set parallel to the work<br />
* Set up a long travel dial indicator to measure carriage motion. <br />
N.B. with the leadscrew stopped, and the threading dial engaged, with its default 16 tooth gear, it will make one turn for every 24 mm of carriage movement (2 mm/div). This isn't accurate enough for positioning but is sufficient to check you aren't out by a whole mm or more.<br />
<br />
Do not allow any solvents to contact the chuck guard clear plastic as it will make the plastic brittle, or even craze it, and try to avoid melting it with the work light!<br />
<br />
=== Slide Locks ===<br />
* The carriage can be locked to the ways using the M5 hex screw through the top of the saddle to the left of the cross-slide. Double check the leadscrew is disengaged and the half-nuts open before locking it. Lock it when facing.<br />
* The cross slide can be locked by a M4 socket headed cap screw just in front of its middle gib screw. Locking the cross slide is helpful when turning very shallow conical features where the cross slide handle is in the way of the compound.<br />
* The compound slide can be locked by a M4 socket headed cap screw in line with the edge of the toolpost mount on the side with the gib adjustment screws. In normal use it should be kept backed off half a turn but it is desirable to tighten it for parting off operations to keep the resulting end faces flat.<br />
<br />
=== Chucks and Chuck Jaws ===<br />
==== Terminology ====<br />
* Inside jaws have steps on the outside to grip the ID of hollow work, but can also be used as outside jaws on small diameter parts (i.e. that fit through the spindle). <br />
* Outside jaws have steps on the inside to grip the OD of the work.<br />
* Universal chucks have a scroll plate with a spiral screw thread that moves all the jaws.<br />
* Independent chucks have individual adjusting screws for each jaw.<br />
<br />
==== The Chucks ====<br />
* The three jaw universal chuck can only grip near round or hexagonal work, which it centers, but its concentricity is not perfect so e.g. if you reverse the work and continue turning at the same diameter from the other end, you will see a line where the turned surfaces meet. It has separate sets of inside and outside jaws, and we normally keep the inside set installed to use as outside jaws for small diameter work.<br />
<br />
** Our jaws are individually numbered, stamped in the groove. They must be fitted in the correct sequence. The jaw slots are not clearly marked. Lowest runout for small dia. parts is achieved if you fit the jaws with #1 anticlockwise of the makers mark, then continue anticlockwise for #2 and #3.<br />
** A large strong rubber band is a great help getting all the jaws started on the scroll together - with slots #1 and #3 above the centerline and the scroll thread outer tip between #1 and #3, insert jaws #1 and #2 and put the rubber band round them to keep them in their slots. Insert jaw #3 and stretch the rubber band over it to hold it up into its slot. If the scroll was positioned correctly, all jaws should be at the same initial radius. The jaws can now be cranked in with the chuck key and they should all engage in step so they meet in the middle.<br />
:: ''Mini-lathe.com have the best instructions for [https://www.mini-lathe.com/mini_lathe/chucks/chucks.htm#Installing_Chuck_Jaws changing the jaws].'' <br />
<br />
* The four independent jaw chuck can grip most roundish or squarish work, which can either be carefully centered by the user, or deliberately gripped off-center. <br />
** Its jaws are reversible so can be swapped from inside to outside by simply cranking each jaw out and reinserting it the other way round, one at a time. DON'T move the jaws to different slots as they are likely to bind.<br />
** When setting up to face the sides of rectangular objects held crossways, it may be helpful to use both inside and outside jaw orientations, in symmetrical opposing pairs.<br />
** Its screws move their jaw 1/8" (3.125 mm) per turn<br />
<br />
* The jaws must '''never''' protrude from the chuck OD by more than one step, and for safety, its preferable they don't protrude at all, as they make the gap between the front of the bed and the chuck body an even more unforgiving meat grinder, and as the number of teeth engaged with the scroll or screw decreases, they loose strength, just when you need it the most to grip larger/heavier work. <br />
<br />
''Neither chuck is well suited to gripping tapered work safely. When seating work that doesn't quite fit through the chuck bore (which is larger than the 20mm spindle bore limit), be careful that it isn't seating on the chamfered edge of the chuck bore as it is far to easy to get the work slightly cocked so it doesn't run true.''<br />
<br />
==== Changing Chucks ====<br />
* When changing chucks, use the small grey plastic mat to protect the ways under the jaws in case you drop the chuck.<br />
* The spindle nose has two patterns of holes - the three hole pattern is for the three jaw chuck and the faceplate, and the four hole pattern is for the four jaw chuck. One hole is shared between the patterns, and is marked on the spindle nose.<br />
* To fit a chuck:<br />
** First check that the spindle nose and chuck back and recess are free of swarf, grit or other debris. Any foreign objects will tilt the chuck causing excessive runout and may mar the surfaces.<br />
** Remove the nuts and split lock washers from its studs, line its studs up with the hole pattern (preferably with the stud nearest anticlockwise to the makers mark through the marked spindle hole), fit and hold it in place with your right hand, and with your left, get the lock washer and nut on the top stud, and take up the slack.<br />
** One one nut is on, you no longer have to worry about dropping it, and can work round fitting the remaining washers and nuts, taking up the slack on each as you fit it. <br />
** Next, work round again getting them all finger tight, then tighten them gently, and finally work round fully tightening them. <br />
* Removal is the reverse of refitting. Put the washers and nuts back on the chuck's studs so they don't get lost.<br />
<br />
=== Faceplate Work ===<br />
Faceplate work is probably the most dangerous operation you can (or rather should) perform on a lathe. The working area is a large diameter spinning surface with protruding clamps to fixture the part that it is impractical to guard. Protruding clamps, studs, nuts etc. are very difficult to see at speed.<br />
<br />
'''Treat the faceplate with great respect and caution if you wish to continue to be able to count to ten on your fingers!''' <br />
<br />
The 65 mm cross-slide travel vs the 80 mm faceplate radius is a serious limitation that may require creative compound, toolpost and tool setups for larger parts, and doing full face cuts in two sections.<br />
<br />
''It is common practice to skim the faceplate to ensure it runs true. We have not (yet) done this, and wont till the spindle is in better bearings and the nose reground to minimise runout.''<br />
<br />
==== Clamping ====<br />
Open ended/sided clamps should be oriented so that cutting forces drive the work towards the clamping bolt/stud, not out from under the clamp. Minimize the protruding length of thread past the clamping nut, if necessary using sacrificial bolts or studs you can cut to length, or even using a long M8 stud for one of the faceplate mountings, so you can get a clamp nearer to the faceplate center. Double-check all clamps are secure, manually turn the faceplate to check the work and clamps clear the ways, top-slide and toolpost, and stand out of the 'line of fire' (a disc extending from the faceplate) when spinning up the work for the first time. <br />
<br />
If you need to machine close to a clamp, consider marking a safe limit circle on the faceplate and work with a marker pen to make it easier to see how close the cutting tool is to crash disaster. <br />
<br />
I strongly advise reading chapter two of Tubal Cain's book "Workholding in the Lathe" several times before your first faceplate setup, and if possible get another experienced lathe user to check your first few setups before spinning them up.<br />
<br />
==== Chuck Guard Removal ====<br />
The faceplate is too large diameter to fit under the chuck guard, but the guard has an interlock switch wqhich must be closed for the lathe to run. The guard is now fitted with wing nuts so it can be removed allowing the the interlock switch to close when using the faceplate. It *SHOULD* *ALWAYS* be refitted if a chuck is fitted, except when turning work too large to clear the guard. <br />
<br />
''The chuck guard is primarily there to make it very difficult to start the lathe without removing the chuck key and to reduce the area of large diameter spinning surface exposed. It may slow down the projectile if a chuck sheds a jaw but is unlikely to stop it. Also it serves to contain coolant spray spun off the chuck. As we don't use flood coolant this usually isn't an issue for us. As setting up for faceplate work doesn't use a chuck key, and the most hazardous zone is the face of the faceplate, with its spinning projecting clamps, with full access required for machining operations, which a guard would not cover, the consensus is that removing the guard is an acceptable risk.''<br />
<br />
=== Turning and Facing ===<br />
We are getting good results in aluminium, brass, and even steel using HSS cutting tools in quick-change tool holders, and the ~ 94 um/turn power feed. Unfortunately due to lack of rigidity in both the machine and smaller diameter parts, if you don't want the outer end to be over diameter, a light final cut and multiple 'spring' passes will probably be required.<br />
<br />
For aluminium, a sharp HSS tool and 0.5 mm (20 div) depth of cut gives good results with power feed for rapid stock removal. Its also easy maths as each cut takes ~ 1 mm off the diameter. Finish cuts should be much finer, 0.1 mm (4 div) is 'in the ballpark'.<br />
<br />
For steel, using carbide insert tooling, a 0.25 mm (10 div) depth of cut is more appropriate, and with pre-applied cutting oil, gives reasonable results with power feed if you use enough speed. The maths is not quite so easy as you are only taking 0.5 mm off the diameter per pass. Again, use finer finish cuts but try to plan your cuts so the final cut is still cutting, not smearing the surface!<br />
<br />
When facing or parting off, some skill is required to turn the cross-slide handwheel steadily to get a decent finish and to avoid shock-loading the tool tip. Increasing the spindle speed in one or more steps to keep up with the reducing diameter is advisable, but avoid speeds that cause resonances (resulting in chatter). When parting off, small through-hole parts may be caught on a thin rod chucked in the tailstock, and pre-positioned inside the work with its tip right up to the parting off position.<br />
<br />
==== Using the Steady Rests ====<br />
For the fixed steady rest, see Blondihacks' Lathe Skills #26 - How To Use a Steady Rest! [[#Youtube_Playlists_&_Videos|{below}]]<br />
<br />
Ours doesn't have ball bearing fingers, so a smooth surface on the work and adequate lubrication are essential. The thumbscrews can only tighten the fingers, so for small adjustments outwards you need to either slack off the clamping nuts or ease them slightly and use a drift against the back of the finger's slot. Once set, check the chuck still turns freely.<br />
<br />
The traveling steady rest needs to run on a machined surface, so at least for the first pass, must follow the tool, so its difficult to avoid using more compound slide overhang than is desirable. An initial surface should be cut next to the chuck or tailstock center before fitting the steady rest.<br />
<br />
Both are a PITA to fit - the fixed one has to have its clamping post inserted up through the bed, and the supplied spanner is useless near the headstock, and the travelling one's mounting holes on the saddle almost invariably need swarf picked out of them.<br />
<br />
==== Turning Between Centers ====<br />
<s>Using a MT3 to MT2 reducing sleeve, the MT2 dead center can be fitted in the spindle.</s> ''Currently the MT3 spindle taper is compromised.'' Alternatively, a soft center can be turned immediately before use in the three jaw chuck, but that must have its 60° point re-cut to concentric if the chuck is disturbed, and needs to be either large enough to bear on the chuck body, or must have a lip to bear on the end face of the jaws to take the axial thrust. Recutting the center is a PITA, as the compound angle must be set to 30° anticlockwise, then reset to a true 0° afterwards. Maybe a right-hand 30° end angle zero rake form tool is the answer, or use the carbide insert tool SSKCR0610H06 as a form tool with the toolpost rotated 15° anticlockwise.<br />
<br />
With the MT2 live center in the tailstock quill, this gives us a center either end of the work to hold it.<br />
<br />
We also need a drive dog similar to [https://littlemachineshop.com/products/product_view.php?ProductID=4473&category=1 this], and the corresponding drive post to bolt to the spindle nose. I have some 25mm bore thick wall iron pipe, which should do nicely. Lengths of the dog's straight tail and of the post TBD after I check how much the center protrudes. N.B. its recommended to tie the tail to the post to keep them in contact so they don't slam. ''Currently we will need to drive from the chuck jaws. Possibly use the exterior jaws with a short soft center gripped on the inside end and drive from the highest step.''<br />
<br />
=== Drilling ===<br />
Always start with a center drill so deflection of longer bits doesn't start the hole off-center. For larger bits (> 5 mm), first drill to the web size, then to final diameter. For a precision hole, drill slightly undersize and ream to final diameter. ''Supply your own reamers!''<br />
<br />
Caution: See note about the quill anti-rotation pin in section [[#Tailstock Quill|Tailstock Quill]] above.<br />
<br />
=== Boring ===<br />
Caution: As the spindle doesn't extend right through the headstock housing, if boring in a through hole, chips tend to fall out the back and tumble in the spindle bore till they fall into the change gears. To avoid this, one should plug the spindle bore with a wad of paper towel or rag and when cleaning up afterwards, use a rod to push it through towards the tailstock, with the chuck jaws (if fitted) wound clear of the spindle bore.<br />
<br />
A swivel bladed hole deburring tool (pale blue handle) can be found in the main room on the windowsill behind the drill press.<br />
<br />
A couple of boring jobs have been bodged with an awkwardly angled turning tool and achieving acceptable effective rake with enough clearance to reach deep enough into the hole has been problematic. I reviewed the tools we had and found none suitable for starting out in a 13mm bore, the max diameter we can (easily) drill. I therefore decided to buy a set of boring bars and make a holder for them. I had difficulty finding anything affordable under 10mm shank - the best low cost option was a [https://www.amazon.co.uk/dp/B07P5LGVBX set of nine 3/8" (9.525 mm) shank brazed carbide tipped boring bars], which would be close to the max capacity of the quick change boring bar holder - if we had one! Unfortunately this holder for our specific toolpost is difficult to find except in a toolpost bundle. Another annoyance is the variable tip height of the set, varying from 1.8 mm to 2.8 mm above the center of the shank.<br />
<br />
I therefore decided to make a boring bar holder of the [https://littlemachineshop.com/products/product_view.php?ProductID=1700 Littlemachineshop.com (USA) style] for use in the four way toolpost, as the additional rigidity will certainly help. Starting with a slightly over 50 mm length of 16 mm aluminium square bar and using the four jaw chuck , both ends were faced and an attempt was made to find its center and center drill it. It was then drilled out to ~9.8 mm after much drama due to blunt drills and drills that cut ~1mm oversize. Too big, but beggars cant be choosers as we didn't have a boring bar holder or a 3/8" reamer. Unfortunately the final hole ended up significantly off center. It was then chucked crossways and ~1 mm skimmed off its thickest side to gain clearance to allow it to be shimmed to height, then one side was slit lengthwise manually with a hacksaw.<br />
<br />
It was fitted to the for way toolpost and loaded with a booring bar, which clamped firmly. A 0.86 mm shim stack brought the tip of the largest boring bar almost spot on center height, with the difference easily accommodated by twisting the tool slightly. The three jaw chuck was then remounted, and a piece of iron pipe chucked for a test. It cuts well and leaves a decent surface finish.<br />
<br />
''The boring bar setup is a work in progress - talk to me before attempting to use them if you have a project that would benefit from boring..''<br />
<br />
ToDo: get something that can sharpen tools tipped with this grade of carbide - it needs some sort of diamond (or possibly CBN) wheel as green grit silicon carbide does little more than polish it. ''N.B. diamond wheels are rapidly eroded by grinding steel, so the supporting steel seat must be undercut with a regular grinding wheel before the diamond wheel can contact it.'' <br />
<br />
We'll also need 50 mm square sheet shims to fit under the toolpost to gain clearance in the toolpost above the tool or toolholder. A 2.4 mm shim would give us about the same above and below spindle center height, and we probably need a small selection of thinner ones.<br />
<br />
=== Thread Cutting ===<br />
The objective is to cut a thread that complies with the ISO metric thread profile. Our lathe is not currently equipped to cut non-metric threads, (with the exception of BA which have pitches based on metric threads of that era).<br />
<br />
[[File:ISO and UTS Thread Dimensions.svg|frame|center|Metric Thread Profile - from the geometry, H is ~86.6% of P]]<br />
<br />
Metric thread data - See 'Preferred Sizes' at: https://en.wikipedia.org/wiki/ISO_metric_screw_thread<br />
<br />
See "Mini Lathe User’s Guide" section '''Threading''' for general techniques *ONLY*, and above for change gears and threading dial setup.<br />
<br />
Amadeal specify the max. thread pitch as 2.5 mm. Any thread pitch greater than 1.5 nn requires the change gears to gear up. When gearing up it is desirable to distribute the ratio as evenly as possible over the two pairs of gears in the geartrain to avoid excessive tooth loading.<br />
<br />
==== External Threading ====<br />
Initially turn work to required Major Diameter, set up change gears and threading tool, touch off on the work, zero the top and cross slide dials, and do a 'scratch' pass to check the pitch. Back off the tool, return the carriage, and re-engage the half nuts on a valid dial line clear of the end of the thread then immediately stop the lathe, and hand turn the chuck till the tool tip is (hopefully) over the scratch to check the thread pickup. If all is good, return the carriage again, restart the lathe and start cutting your thread. <br />
<br />
Methods of doing so vary depending on the size of the thread and toughness of the metal, but straight-in plunge cutting is generally to be avoided as has the highest cutting forces, and does not reliably keep the carriage (and top-slide if set parallel to the work) loaded to avoid pitch errors due to backlash. <br />
<br />
If leaving the half-nuts engaged and reversing the lathe to return to the start of the thread for the next pass, its absolutely essential to back the tool out of the thread for the return pass as it will not follow the path of the cutting pass due to backlash in the geartrain, leadscrew mounts and half-nuts.<br />
<br />
==== Internal Threading ====<br />
''<nothing here yet>''<br />
<br />
== Cutting fluids ==<br />
=== Why bother? ===<br />
[https://youtu.be/mRuSYQ5Npek Watch this video] and contemplate what's actually happening to that thin ribbon of metal being removed. Most of the lathe's motor power is being turned into heat by internal friction in the chip being removed in the zone around the cutting edge, and surface friction at, and immediately behind the cutting edge, near-instantly heating the chip by up to several hundred degrees. Reducing the surface friction using a suitable cutting oil reduces the strain on the machine as a whole, and reduces workpiece and tool heating (and thus expansion) with consequent improvements in maximum usable feed and depth of cut, surface finish and accuracy. It also drastically increases the life of the cutting edge.<br />
<br />
=== Practicalities === <br />
We don't have a coolant system for the lathe and *really* don't want the maintenance hassles of using soluble cutting oil/coolant as if used infrequently its a PITA to keep recirculated high water content cutting fluids from going rancid and stinky, and they can also rust the ways, so even a total loss gravity feed system is problematic. Therefore if dry machining doesn't give a good enough finish, we tend to use oil applied topically, by hand to the work. <br />
<br />
* Hard brass is typically free-turning without oil, however some light oil for the final cut can improve surface finish, but with the disadvantage that it will increase loose chip buildup on the tool as hard brass typically forms short spalls or splinters rather than curly chips.<br />
<br />
* Many Aluminium alloys tend to be gummy, and Paraffin or other mineral spirits mixed with a little oil can help prevent the aluminum welding to the tool edge. WD40 will do at a pinch, but its messy to apply from a spray can.<br />
<br />
* Steel really needs *GOOD* cutting oil. Lard oil is the traditional choice for steel. If there are any objections to lard oil, we should bite the bullet and get some commercial dark high Sulphur cutting oil, but beware, many such oils use an additive package that includes lard oil.<br />
* Cast iron (except ductile) should be cut dry, as the carbon micro-inclusions self-lubricate it, and the carbide in the dust (primarily Cementite) are very abrasive, so tend to form a grinding compound if mixed with oil. <br />
<br />
I've sorted out an oil pot lid with a 1/2" brass collar soldered in to give a nice smooth sided hole, for ease of use and to minimize the risk of spills when using a brush to apply cutting oils, and got some dirt-cheap brushes. It fits Shippam's paste (and similar own-brand spread) jars and I've found several jars and ordinary lids to seal them for storage. Unfortunately it isn't the easiest to get this type of jars' lids back on square so they seal properly, and if you over-tighten them and there's a temperature change, they can be a total <expletive> to reopen. Using the rubberised handles of a large pair of pliers to grip the jar lid just above its rim is the best option, and avoids damaging the lids.<br />
<br />
''N.B. For the smaller brushes, the glue holding the bristles in is attacked by paraffin. To prevent loss of bristles, crimp the aluminium ferrule of each new brush of this type before use.''<br />
<br />
We have, in labelled jars:<br />
<br />
* Sulphurised Lard oil thinned with paraffin. Best choice for heavy cuts and threading in steel but stinky.<br />
* Lard oil thinned with paraffin. Good for steel and acceptable for softer copper alloys<br />
* Paraffin with a trace of light oil. Good for aluminium, and can help prevent squealing chatter on finish cuts in brass.<br />
<br />
I've also got some paraffin wax (in the form of a stubby candle), which can be applied lightly (under power) to brass and aluminium stock especially on the finish pass. It makes less mess than oil but unfortunately tends to build up on the tool tip, making it difficult to 'work by eye' without frequent pauses to clean the tool tip.<br />
<br />
We've also got a tin of [https://www.rocol.com/products/rtd-compound Rocol RTD cutting compound], which is a thick paste. Its highly recommended for drilling and tapping steel (in the drill press or by hand), but as a paste, is less useful for general lathe work unless thinned to a fluid consistency, e.g. with paraffin or white spirits. OTOH its certainly worth trying for high speed facing steel as it is less likely to get flung off.<br />
<br />
== Cleaning and Maintenance ==<br />
Swarf is a significant cut hazard to the operator, especially stringy swarf from cutting steel. Never touch it bare-handed - always use a tool e.g. a brush, or a hook, or needle nose pliers for grabbing long swarf.<br />
<br />
* After use, brush all swarf off the toolholder, compound and cross slide etc. ways and leadscrew. Ian B has blocked off the opening at the headstock end of the rear splashguard (to try to keep swarf out of the motor), so one must sweep the swarf towards the open tailstock end and catch it in a dustpan or similar. Preferably, also thoroughly clean out the chip tray under the lathe, but at least sweep out visible swarf.<br />
* Wipe up any cutting fluid residue and re-lubricate affected sliding surfaces with way oil.<br />
* Do not solvent clean the chuck guard, as it will make the plastic brittle, or even craze it. Water with a little detergent is permissible for cleaning it, with the guard totally removed from the lathe.<br />
<br />
Before engaging the half-nuts for power feed/threading, check the leadscrew is clean! ''Best cleaned under power, with a toothbrush.'' <br />
<br />
'''Caution:''' The traverse gears behind the carriage handwheel are in an open-backed housing and tend to become packed with swarf! Swarf buildup here will result in jerky carriage movement. Clean out as much as you can with a toothbrush ...<br />
<br />
===Lack of lubrication and/or swarf or dirt build-up can be disastrous===<br />
* If using the change gears/power feed, lack of lubrication of the B-C stub shaft center pin or either leadscrew end bearing can result in seizure and immediate destruction of one or more gears in the gear train or worse. <br />
* Small pieces of swarf can get between the saddle and ways, or into the slides degrading accuracy, possibly permanently if hard swarf scores them, or jamming them. The carriage handwheel gears behind the apron are notorious for accumulating swarf, and swarf buildup on the leadscrew can prevent the half-nuts engaging properly, resulting in scrapped work, and possibly stripped half-nuts. <br />
* Metal swarf can get into the motor (''though Ian B has modified the rear chip catcher to reduce the risk)'' or into the control box via the leadscrew, and short-circuit stuff. At best it will blow the fuse and need a strip-down to clean it out, at worst it may require a replacement [https://www.amadeal.co.uk/acatalog/Speed-Control-Circuit-Board--12amp-AMA_SP_CJ18_SCB12.html#SID=12 speed controller] ''(currently £96)'' and/or [https://www.amadeal.co.uk/acatalog/550W-motor-for-CJ18A-Mini-Lathe-467.html#SID=240 motor] ''(currently £105)'' and possibly other electrical parts. We should probably fit a [https://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C3-Mini-Lathe-Spares/C3-256-Leadscrew-Grommet-Dustproof-Cover C3-256 Leadscrew Grommet] to keep swarf out of the control box, as it tends to drop onto the 'Filter' board which is mounted horizontally, below the leadscrew.<br />
* Grit from grinding, sanding etc. forms a grinding paste with the way oil, and will rapidly wear out the ways, saddle and slides. Keep grit off at all costs e.g. by covering the ways and slides during grinding/sanding operations, and if there's any chance grit has gotten where it shouldn't, clean and re-lubricate *BEFORE* moving the carriage or slides, then move the carriage and slides, wipe down where they were with a clean paper towel and check there's no remaining traces of dirt other than clean way oil on the paper towel. If it doesn't come clean when you re-lubricate and move it again, a full strip down may be required to solvent clean and relubricate the precision sliding surfaces.<br />
* Although a metalworking lathe *can* be used to turn hardwood, wood dust and small chips are extremely pernicious, as they get everywhere, even clinging to clean surfaces, are abrasive due to their silica content, and are hygroscopic, promoting rust. An even more thorough clean-up than after using abrasives is needed, immediately afterwards. Oily wood dust and fine wood chips in significant quantities are a fire hazard, even in the trash bin.<br />
<br />
===Lubrication===<br />
See section: "Lubrication" in LittleMachineShop.com "Mini Lathe User’s Guide" [[Ian_M's_Lathe_Notes#Manuals|(below)]]. As we usually only open two nights a week, in the table on page 16, Daily lubrication becomes Weekly and Weekly becomes Monthly.<br />
<br />
===General Maintenance===<br />
* The grubscrews holding the cross-slide and compound slide dials tend to loosen due to vibration and use of the dials. Keep them snugged up, but not so tight the dials cant be set without an Allen key.<br />
<br />
* The screws holding the cross-slide nut tend to work loose due to vibration. Crank the handle to and fro through the backlash and visually check there is no movement of the screw heads in their holes. If there is, see the [[#Excessive_cross-slide_backlash|notes below]].<br />
<br />
===Removing the Carriage===<br />
Its possible to remove the carriage from the bed for cleaning etc. without dismantling it. The only stop to its motion is the righthand leadscrew bearing.<br />
<br />
Start by removing the tailstock. Crank the carriage to the tailstock end then remove the leadscrew bearing (two screws and a nyloc nut on the leadscrew end). With the half-nuts open, hold the leadscrew centered in them and crank the carriage off the end of its rack, then slide it off the end of the bed.<br />
<br />
Refitting is the reverse of removal, except (if its gibs are correctly adjusted) the carriage will be very tight on the end of the bed ways so may be difficult to work onto the ways without a stack of blocks of wood or similar to support it at exactly the right height. The righthand leadscrew bearing must be refitted with the carriage as close as possible to it and the half-nuts firmly closed to support the leadscrew at the correct height to hold it in alignment while the screws are being tightened. The nyloc nut controls leadscrew end-play. Fully tighten it then back it off slightly till the leadscrew turns freely with its change gear removed.<br />
<br />
If the Apron has been off, refit it with the screws no more than lightly finger tight and only finally tighten them after checking lead screw engagement at both ends of the carriage travel and that the rack and pinion operates smoothly over the full travel.<br />
<br />
== Issues and Annoyances ==<br />
As of September 2023 - mostly resolved, apart from the spindle bearings and runout, the lathe is in better condition than it has been for a number of years.<br />
<br />
===Four Jaw Chuck has two jaws too tight===<br />
Fixed 27/10/2023: Two of the chuck jaws were tight in their slots, making precise adjustment difficult due to lack of 'feel'. Moving the jaws round the slots showed the problem mostly followed the jaw not the slot. The grooves in the opposite sides of the affected jaws that run in the chuck slots were slightly out of true, and the rails either side of the slots were slightly too thick towards the center. Due to the difficulty of seeing the high spots, after cleaning up and deburring the jaws didn't do enough to ease them, I decided to grind the top of the rails where they were binding. Several repetitions of spotting with Engineer's blue, grinding, then diamond filing the high spots has eased them enough. I cleaned everything, greased the jaw slides and screws, and refitted the studs so the chuck is now fit for service.<br />
<br />
''N.B. Don't move the jaws to a different slot - the formerly tight jaws *must* stay in the slots furthest from the makers mark.''<br />
<br />
===Excessive Runout===<br />
Mostly fixed 24/10/2022: I ground the chuck seating surface of the spindle nose (outside lip) to under half a thou runout. This also cleaned up several burrs. It would be possible to do better, but that would need good spindle bearings, and a more rigid toolpost grinder mount.<br />
<br />
Our spindle nose was damaged years ago by a person with little mechanical aptitude (who shall remain nameless) beating it up with a hammer mushrooming the spindle nose. We are getting several thousandths runout at the end of the MT3 bore, a MT3 to MT2 reducer sleeve in it runs visibly out of true, as does the spindle nose flange. When you put a chuck on it, the runout is magnified by the distance from the spindle nose. Ideally we would replace the spindle when we change the bearings but its £52 [https://www.amadeal.co.uk/acatalog/4-Spindle-Upgrade-Real-Bull-Mini-lathe-CJ18-series-AMA_SP_CJ18_003RB.html#SID=9 from Amadeal] and money is tight. It may well require more work after the bearing upgrade. Once good bearings are in, if we can borrow a decent MT3 arbour as a reference, we should consider skimming the bore.<br />
<br />
===Spindle bearings===<br />
* The spindle bearings appear to be close to worn out. They are notably noisy when running, and there appears to be more slop in the spindle than is desirable. There is notable resonance around 600 RPM, and surface finish of end faces is often poor. We have some ideas for possible replacement/upgrade, but it requires a major teardown.<br />
<br />
: The original bearings are allegedly 6206-2RS or 6206-ZZ deep groove ball bearings - 2RS codes rubber seals both sides and ZZ codes metal shields. Although the deep groove gives reasonable ability to withstand axial loads, the bearing balls point contact means they are vulnerable to [https://en.wikipedia.org/wiki/Brinelling brinelling] due to shock loading. The jammed on three jaw chuck didn't help this, as before we skimmed the spindle nose lip, it had to be driven off using a bar through the spindle bore, shock loading the bearings every time. Also even a minor 'crash' could have brinelled them due to eccentric shock loading, and the lathe has previously been crashed badly enough to need drive gear replacement. There are also issues with the 'approved' method of spindle and bearing removal from the headstock brinelling them, even if you don't abuse the spindle nose with a hammer!<br />
<br />
: A possible replacement is 30206 tapered roller bearings. The new bearings are slightly thicker so the plastic spindle spacer (15) needs to be machined to length to get the 45 tooth spur gear that drives the change gears laterally aligned with the tumbler gears. If a temporary replacement (3D printed?) is fitted, the lathe can be run (without power feed capability) so this can be done on the lathe after fitting the new bearings. As tapered roller bearings have line contact, they are significantly more resistant to brinelling.<br />
<br />
: ''See [[Talk:Ian_M%27s_Lathe_Notes]] for notes, links etc. for this upgrade.''<br />
<br />
===Motor stuttering===<br />
* Fixed 21/09/2023: The motor was running very erratically and it was very difficult to set a speed. Several loose connections were found in the control box, mostly loose female spades to the motor controller board, but also a dry jointed braking resistor on the 'Filter' board, and an inhibit wire completely off its terminal on the forward/reverse switch, making intermittent contact. After tightening and/or remaking all affected connections, it was much improved but still not right below 300 RPM. The remaining issues were due to poor wiper contact in the speed control pot, and stripping it, cleaning the track and contact ring and re-tensioning the contacts resulted in the motor now running smoothly over the full speed range. The speed is slow to settle, and while part of that is probably the lag in the digital tach, I suspect that the KBIC motor speed controller isn't properly tuned as it was (allegedly) previously replaced.<br />
<br />
===Drive belt slipping===<br />
* Fixed 28/9/2022: During testing the motor after the above issue, it was noted that the chuck could be stalled, slipping the drive belt, with not much torque. The drive belt was determined to be loose and a bit worn, but still in acceptable condition. <br />
<br />
: Access for servicing the belt requires removing the control box ''(2 spades to ZVR switch disconnect the supply, speed sensor and motor simply unplug from the 'filter board')'', the motor cover, chuck guard switch assembly + wiring cover, the change gear 'A' (drive) shaft carrier assembly, and the tumbler gear assembly. See https://youtu.be/EkxlIz01BdA for disassembly/reassembly, though on our lathe, the speed encoder ring on the spindle prevents the belt cover from being fully removed without disturbing the spindle nuts. There is enough room to work with it loose, but still trapped by the encoder ring. Also, unlike the video, if the 'jack' screws under the headstock are correctly adjusted, and the studs aren't excessively bent, there is no need to make custom studs. <br />
<br />
: It turns out that our lathe was missing the M6 hex headed jack screws that press the motor down to resist the belt tension, and the motor had cocked out of position at a severe angle. I know Ian B had had considerable trouble adjusting it after the motor fault back in October 2022, and I believe it had been getting slowly worse ever since. The jack screws were probably mistaken for headstock fixing bolts during disassembly after the crash that resulted in the metal Hi/Lo gears being fitted, then lost. The penny washers on the studs had dished, so I turned them over and backed them up with smaller washers and switched to Nyloc nuts so they cant back off due to vibration. N.B. There is a packing washer on the motor side on one of the studs, presumably so the shaft is true to the ways. Adjusting the motor is awkward to say the least. One has to slack the stud nuts off a lot, pry under its rear end to lift it enough to be parallel to the ways, snug the stud nuts, check alignment, then set the jack screws and their lock nuts to hold it there, and finally tighten the stud nuts. <br />
<br />
: Tension: According to Sieg, it should be possible to twist the belt 90° mid span with a light finger grip. Other sources say 1/32" - 3/32" deflection mid span with light finger pressure.<br />
<br />
===Speed display blanking===<br />
* The speed display has been intermittent, blanking and flashing 8888 and 0 at certain speeds for as long as I have been using the lathe. Finally on 18/07/2022 it failed completely, with no display. I removed the display module and bench tested it - the pins are labelled 5V GND PL PE, PE is frame ground and PL is a TTL level pulse from the speed sensor - confirming that it was in good working order. My suspicions then turned to its power supply on the 'Filter' board. With both the sensor and display unplugged, the 5V rail was found to have a only a couple of volts, but the unreg DC was 17V and stable. Replacing the 78L05 5V regulator restored the 5V rail and normal operation.<br />
<br />
: ''I conclude its been failing for a while with high load current due to speeds with more lit segments causing it to drop out, resetting the speed display, causing it to blank, lowering the current enough for the regulator to recover, then the display MCU lamp tests (8888) then re-acquires the speed, repeating ad-nauseum till the speed is changed. I don't like the design as the high input voltage results in excessive dissipation.'' <br />
<br />
: ''ToDo: If it fails again, bench test display to measure its worst case current consumption, then fit an appropriate dropper resistor to reduce the 78L05 dissipation.''<br />
<br />
===Quill spinning when drilling===<br />
* The quill was tending to spin while drilling because its anti-rotation pin (a M5 dog tip setscrew) was sheered. I've removed the debris, aligned the scale with the top of the tailstock and fitted a longer M5 dog-tip setscrew to replace it, with a nut to lock it at the correct height. N.B. the pin isn't that 'meaty' so if using big drills in tough metals, to prevent shearing it, it should be backed out so the quill can be turned by hand and unwanted rotation controlled by being quick with the quill lock if it starts to spin, or even using a close fitting rod in one of the chuck key holes with plastic tube over it to protect the ways. <br />
: ''If the screw sheers again, the quill will need to be removed and the tailstock taken off the lathe so the sheered tip can be shaken out, and if the setscrew is difficult to remove it probably means the threads are mangled where it sheered. Try driving it right through with the quill out.''<br />
<br />
===Sloppy quick change toolpost locking mechanism===<br />
* Once the dovetail clamp screw was slackened, there was nothing preventing the dovetail twisting or cocking significantly, and friction with the toolholder made it tend to do so, making toolholder insertion and removal more difficult unless the clamping screw was backed off excessively. I added a compression spring around the clamp screw inside the toolpost to push the dovetail outwards so it mostly retains alignment when open, allowing toolholders to slide on or off cleanly with far less screw slackening.<br />
<br />
===Leadscrew rubbing===<br />
* The leadscrew shaft is rubbing on the insulating separator inside the control box. Unfortunately the corner of the relay on the Filter Control Board (#160) doesn't allow enough clearance. Although the friction isn't much of a problem at high reduction ratios, e.g. 16:1 power feed, it increases the stress on the change gear train, and may be problematic when threading at feeds above 1:1. ''Possibly pack out the control box mountings by a couple of mm.'' <br />
<br />
===High/Low lever backwards!===<br />
* The high-low drive gear selector behind the headstock is incorrectly labelled and differs from the manual: low gear (which we normally use) is with the lever towards the tailstock. ''I suspect that the gears in the headstock were refitted the wrong way round when it was upgraded to metal gears.''<br />
<br />
: ''ToDo: Get it reassembled the right way round during the spindle bearing upgrade!''<br />
<br />
===Carriage lock fouls top slide===<br />
* The T handscrew has been replaced with a M5 hex headed bolt, to permit access when the top slide is over it. An 1/4" drive 8mm socket is usually left on it, but needs to be removed when the full cross slide travel is needed. The small (4 jaw) chuck key is near enough 1/4" to use for it. If you need to (un)lock it while the compound is over it, you'll need an 8mm spanner. ''The [https://www.amadeal.co.uk/acatalog/Mini-Lathe-Carriage-Lock-463.html Amadeal lock screw] is in the spares tin as it was too high and fouled the compound slide.''<br />
<br />
===Tailstock locking lever loose===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock - See full image for key to screws]]<br />
* Diagnosed and fixed 10/1/2023 - In the base of the upper section of the tailstock, there are two dog tip set screws that engage with locating grooves in the counter-rotating shafts carrying the eccentric locking cams. They'd backed off, probably due to vibration. They need to be tightened till they bottom out in the groove, making sure they are '''in''' the groove, backed off half a turn so the shafts can turn easily, and locked in place. There's no facility to do so, so reassemble with weak threadlocker. Unfortunately to get to them you have to remove the tailstock base slide, which is held on by the pressure of four adjusting grub screws, which all need backing off, and one socket headed bolt from underneath so full tailstock realignment is required after reassembly, which even for a rough alignment is tedious.<br />
: <s>The tailstock locking lever is loose and can be pulled out on its axis. It works OK when fully pushed home but needs investigating. ''I tightened the grub screw as the lever was coming off its shaft, but the whole shaft pushes/pulls in and out. It works OK fully pushed in, but it seems something that is meant to retain it has failed inside the tailstock base.</s><br />
<br />
===Gear alignment issues===<br />
* Change gear alignment is poor. I've currently got a gapped washer (to clear the key) packing out the A shaft so the gears line up, but this reduces the key's engagement so is problematic due to the high loading if the gears are set up for coarser threads. <s>Also I need to turn down some penny washers to slightly less than the root diameter of the metal 20T pinions, as gear retaining washers.</s> ''The gear retaining washers for A gear and B-C stub shaft are now done, turned down to slightly under 16 mm dia. Spares in the change gear tin. ToDo: The D (leadscrew) washer requires a larger center hole, so make two more with that hole.'' <br />
<br />
===Saddle gibs loose===<br />
* Fixed 11/04/2023: I took the apron off for access (and to clean the carriage handwheel gears), and found the front sheer plate screws were completely loose. I've snugged them up some and set the opposing grub screws and got a lot of the slop out. I've re-checked the front ones, and taken up the slop in the rear ones - Unfortunately it wasn't possible to get carriage movement to have an even 'feel' over its whole travel, and its noticeably tighter near the tailstock. If light hand pressure on the side of the unlocked carriage can cause movement (with the half-nuts open), its time to readjust them again, though it should be possible to move the carriage with a firm push. <s>The saddle gibs (actually the sheer plates) were too loose, to the point that engaging a slightly stiff threading dial could cause it to self-feed, an obvious crash hazard if working near the chuck or a step in the work.</s><br />
<br />
''N.B. the lefthand front opposing grubscrew is short, (fully recessed) and unlike the others does *NOT* have a locking nut as it must clear the traverse pinion. A wrap of PTFE tape provides enough friction to keep it in place, though possibly a bit of nylon fishing line down its hole would be better.''<br />
<br />
===Excessive cross-slide backlash===<br />
* ''Fixed 21/11/2023.'' Originally, back in October 2023, The cross-slide screw had excessive backlash (nearly three turns), which increases the risk of loosing track of the cut depth when cutting steps, and during threading operations. If you ended up off by a turn too far in, a crash would be the most likely outcome.<br />
: The original excessive backlash was traced to loose cross-slide screw nut mountings. The nut has two socket headed cap screws pulling up, one either end, accessible from the top of the cross-slide, which control the tilt of the nut to take up backlash in the nut, and an opposing grub screw pressing down on the center of the nut to make it longitudinally rigid. Snugging up the grub screw reduced the backlash to 10 divisions or so, or 0.25 mm. A year later, the backlash had increased to one turn due to the cross-slide nut mounting screws working loose again.<br />
<br />
: 07/11/2023: I investigated further: It is difficult to get the cross-slide nut aligned correctly as it must be at the same height as the screw which is constrained by the bearing surfaces in the bracket. With the cross-slide almost at the front limit of its travel, I removed the screw and set the nut as level as possible and visually centered in the bore, then re-fitted the bracket and screw, then adjusted the tilt till it turned freely through the backlash. I then tilted it up at the front till some drag was felt to minimise the backlash and tightened the screws to lock it in place balancing them to maintain the same feel as I tightened them. The result was 7 divisions of backlash, acceptable but not great. During normal turning operations, the load on the nut is tension on the front screw and pressure on the grubscrew, so if it slackens again due to vibration from chatter, odds are it will be the rear screw that's loosened.<br />
<br />
: 16/11/2023 - 21/11/2023: The backlash had crept back up to 11 divisions (0.275 mm). We don't have any >14 mm brass stock (or even near that) so I tried making the shim washer out of aluminium. I was shooting for 0.24 mm but due to poor technique got 0.28 mm. No good - locked solid. I lapped it down and tried it till I got it down to 0.20 mm which gave about 3 divisions backlash - good enough, but the screw was too tight due to the shim washer not being bevelled at its outer edge resulting in it cupping in its seat. Filing a bevel round the OD and re-lapping it resulted in a 3 - 4 divisions of backlash. Its a little mushy due to the washer having been kinked removing it, so ideally a new (brass) washer should be made. <br />
<br />
* Further reduction of backlash: https://youtu.be/Wu_tI29JL2Y?t=163 <br />
: Brass tinned with Pb-free solder to form a white metal bearing surface should work at least as well as the bronze used in the video. The shim washer needs to be 10.2mm ID, with a full thickness bevel on a 14 mm OD. It isn't necessary to remove the lead screw from the cross slide, as the washer can be fitted in-situ with only the bracket removed.<br />
<br />
===3 Jaw chuck didn't mount properly===<br />
* Fixed 7/4/2023 by grinding the spindle nose lip. The three jaw chuck can now be installed and removed by hand with no hammering. A test bar in it now has only 2 thou runout (TIR) at the chuck.<br />
: <s>The three jaw chuck and the faceplate aren't seating properly on the spindle nose. Its too tight on the register diameter of the lip. This results in grossly excessive runout, and also makes this chuck and the faceplate a PITA to fit or remove.</s><br />
: ''The spindle nose had been abused with a hammer (before my time) which mushroomed it and may have brinelled its bearings. See '''Excessive Runout''' and '''Spindle bearings''' above.''<br />
<br />
== Manuals, Books and other resources ==<br />
=== Manuals ===<br />
The [https://wiki.richmondmakerlabs.uk/images/a/a3/Lathe_InductionNotes.pdf RML CJ18A Mini-Lathe Induction Notes]. Your mandatory Lathe Induction will cover most of this but its good to be able to refer back to it.<br />
<br />
Official [https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Amadeal CJ18A Manual], or paper copy (less complete) kept on shelf above lathe.<br />
<br />
The [https://www.chesterhobbystore.com/wp-content/uploads/2022/11/Conquest-Super-Lathe.pdf Conquest Super Lathe manual] is considerably better than the Amadeal manual and is for a near-identical machine.<br />
<br />
The [https://littlemachineshop.com/images/gallery/info/minilatheusersguide.pdf Mini Lathe User’s Guide] from LittleMachineShop.com is even more comprehensive, going into its usage in some detail, with a proper TOC, and covers both US and Metric versions of Realbull Mini-lathes. ''The only fly in the ointment is the threading section assumes a US lead screw so change gear selections and threading dial divisions will not be correct for our lathe.''<br />
<br />
[https://www.arceurotrade.co.uk/machineguides/C3-Mini-Lathe-Dismantling-and-Reassembly-Guide.pdf Sieg C3 Mini-lathe Dismantling and Reassembly Guide] "A picture story book to help you dismantle and reassemble your Sieg C3 Mini-Lathe" ''It is similar enough to ours to serve as a maintenance guide, except for the electronics, spindle drive and other headstock innards.<br />
<br />
The motor controller is a clone of a [https://acim.nidec.com/drives/kbelectronics/-/media/kbelectronics/documents/dc-drives/manuals/kbic_manual.ashx?la=en KBIC® SCR DC Motor Speed Control]<br />
<br />
=== Books ===<br />
'''Metal Turning on the Lathe''', by David A Clark, Crowood Metalworking Guides, ISBN-13: 978-1847975232 [https://www.amazon.co.uk/gp/product/B00E78RKIG Kindle Edition (£8.99)]. ''A 'free' epub can be googled for, *NOT* linked here due to dubious legality.''<br />
<br />
'''[https://archive.org/details/03screwcuttinginthelathe Screwcutting In The Lathe]''', by Martin Cleeve (a pen-name of Kenneth C Hart), Workshop Practice series #3, ISBN-13: 9780852428382<br />
<br />
'''[https://archive.org/details/15workholdinginthelathe Workholding in the Lathe]''', by 'Tubal Cain' (a pen-name of Tom Walsh), Workshop Practice series #15, Argus Books, ISBN-10: 0852429088<br />
<br />
'''[https://archive.org/details/20metalworkandmachininghintsandtips Metalwork and Machining Hints and Tips]''', by Ian Bradley, Workshop Practice series #20, ISBN-13: 9780852429471<br />
<br />
'''[https://archive.org/details/38toolandcuttersharpening Tool and Cutter Sharpening]''', by Harold Hall, Workshop Practice series #38, ISBN-13: 9781854862419<br />
<br />
'''[https://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpaperT204.pdf Cutting Fluids]''', by EC Bingham, NIST Tech. Paper No. 204, 1921<br />
<br />
=== WWW resources ===<br />
==== Mini-lathe Specific ====<br />
There's a *LOT* of mini-lathe info online. Notable sites include:<br />
* http://www.mini-lathe.com/ - A major Realbull/Sieg mini-lathe resource.<br />
* http://mikesworkshop.weebly.com/lathe-modifications.html - many mods including carriage DRO autostop, and variable speed leadscrew motor drive, cross-slide motor drive, etc. He also has a page with a bunch of accessories, toolholders etc. - http://mikesworkshop.weebly.com/lathe-accessories-and-tooling.html<br />
* http://andysmachines.weebly.com/variable-speed-controls.html - Scroll down to the 'UPDATE' section for the schematic of a very similar SCR speed control board. It also has the schematic for an earlier version of the Auxiliary Control Board (aka: 'Filter' board).<br />
<br />
==== Forums ====<br />
''with publicly accessible archives''<br />
* https://groups.io/g/7x12MiniLathe - Mini-lathe specific, active<br />
* https://www.hobby-machinist.com/forums/mini-lathe-mini-mill-information.220/ - active<br />
==== Youtube Playlists & Videos ====<br />
* Blondihacks: [https://www.youtube.com/playlist?list=PLY67-4BrEae9Ad91LPRIhcLJM9fO-HJyN Lathe Skills] (playlist) - "This is an educational series to help you learn to use your metal lathe. Watch them in order for best results! Satisfaction not guaranteed, especially if you're a cranky sort of person."<br />
* Frank Hoose (Minilathe.com) has a couple of relevant Youtube playlists:<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn7ON0jGM5UbM-KZDT56MOIp Mini Lathe Operations]<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn4nGRZaVq3wTOlvZNOmdAZ2 Mini Lathe Overview]<br />
<br />
==== General Machining ====<br />
* https://www.machiningdoctor.com/ - "THE #1 MACHINING TECHNICAL HUB"<br />
<br />
==Projects==<br />
[[File:VESA mount.jpg|thumb|Machined VESA mounting plate (left) and plate from Dell monitor stand it must match (right). The translucent washer shows the size of the original center hole.]]<br />
* My first faceplate project was boring out the center hole in a VESA mounting plate to adapt it to fit onto a surplus Dell 1708FP monitor stand. The part was centered using the tailstock dead center engaging with its original center hole. I clamped the part with studs and penny washers on the driving side of two opposite corners, with cap screws in the next slot round to trap the corners under the clamping washers, then withdrew the tailstock and dead center. After machining out the bore, I used the tip of the tool, rotating the chuck by hand, to scribe a circle for laying out the bolt holes. I finished off laying out and drilling the bolt and locating holes by hand at home, fitted it to the stand, and mounted the 2nd hand LG 24" widescreen monitor.<br />
<br />
* Another ultimately unsuccessful project was fly cutting aluminum flat bar to thickness to make custom shims for the set of carbide insert tools, for the four way toolpost. The 8 mm shank tools need ~2.5 mm shim stacks, and the 6 mm shank tools need ~4.5 mm shim stacks. Ideally I'd machine single shims, but the only stock I've got handy cleans up to only 3.2mm, and some fine shimming may be needed to fine-tune the tool height.<br />
<br />
: After sorting out the clamps so they were no longer twisting the aluminum flat bar stock, and switching to the short 45° turning SCMT06204 insert tool in the four way toolpost, to improve rigidity and get a well controlled tip radius, the finish was much improved. I'm still having problems getting an even thickness and am getting approx. 0.05mm variation, I suspect due to the aluminium bar stock distorting due to internal stresses as its surface is cut away. ''ToDo: try supergluing the stock to the faceplate before clamping to further reduce chatter and stop the warping.''<br />
: Looking back on this project a year later, its fairly obvious that the thickness variation was probably due to faceplate surface runout due to the damaged spindle nose.<br />
<br />
* Raphael has been working on a steel rocket nozzle with some assistance from myself. We have set up the rough cut chunk of ~ 50mm steel bar, faced both ends (to 50mm length) and turned the OD to 49mm to clean it up. Its going to need through drilling, probably some boring, and quite a bit of detail work on the OD. It will then need to be transferred to a jig in the drill press vice to allow a pattern of angled traverse holes to be drilled with acceptable accuracy.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_%C2%A399_ZHUHAI_CTC_DiY_I3_3D_printer&diff=17599Ian M's £99 ZHUHAI CTC DiY I3 3D printer2023-12-15T11:26:46Z<p>IanM: /* 15 December 2023 */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br><br />
<br />
The ZHUHAI CTC DiY I3 Pro B 'Prusa' clone printer is rather similar to RML's [[Geetech I3 Pro B]] except with a laser cut plywood frame instead of acrylic, and cheapened in many key areas, which I'm working on upgrading. Its my personal 3D printer and is not kept at RML.<br />
[[File:Ian's CTC I3 After BLtouch upgrade.jpg|thumb]]<br />
== The DiY kit and the build ==<br />
Here's CTC's official build video: https://youtu.be/PSzcU48wczk<br />
=== Differences on my printer ===<br />
* IEC power inlet (Video has direct attached mains lead)<br />
* Bed levelling screws have countersunk heads so there are no obstructions at the bed corners<br />
<br />
=== Hints & Tips that didn't make it into the build log ===<br />
* Buy a pack of M3 washers and insert one in each T-slot in the frame, between the nut and the wood it bears on, to spread the pressure and prevent the nut chewing the wood.<br />
<br />
* A pair of M8 nuts can be used to 'hang' the lead screws and gantry assembly from the top of the frame while working on the steppers or shaft couplers.<br />
* Put a *VERY* large cable tie right round the body of the extruder and X steppers, with the tail coming straight up at the back of the extruder, and straight down off the X stepper, then cable tie the wiring to the big tail to anchor it before you spiral wrap, Leave the big tail full length inside the spiral wrap to stiffen the loom near the motor. A similar large cable tie round the lower right board fan standoff, snug but not tight so it can pivot on the standoff, can be used to anchor the lower end of the X loom.<br />
<br />
* The 2004 control/display PCB is probably being warped by its plywood frame and the absence of spacers between the board and the back not allowing for the solder joints with slightly protruding header pins. Dismantle it and shim for clearance behind the board with nuts/washers/etc. taking care not to short anything. You may need to file out the bolt holes in the ply so the board fits properly without being forced into a curve before reassembling and mounting it.<br />
<br />
== Build log from my posts on the RML Telegram group ==<br />
''Currently, a mostly verbatim copy of my 3D printer related posts, with some corrections and additions to my posts + some responses to my posts from other members. If you feel I've misrepresented what you said, or you don't want to be quoted, and you don't have edit rights here, PM me on Telegram!''<br><br />
<br><br />
''ToDo: Transfer more stuff from Telegram here and edit it into a coherent project writeup.''<br />
<br />
=== 6 Jan 2022 - Arrival and initial mechanical assembly ===<br />
A cheap (£99) Prusa i3 clone 3D printer kit should be landing on my doorstep later on this afternoon . . .<br><br><br />
{<s>photo from manual</s>, ''not posted here due to copyright''}<br><br><br />
It arrived.<br><br />
Its actually a ZUHAI CTC DiY I3 PRINTER with a wooden frame, and an ANET A8 v1.5 clone controller board. That’s more or less what I expected as a *real* Prusa for under a ton just isn't happening unless its a BER parts mule. Next: dig through the documentation, such as it is . . .<br><br />
<br><br />
''Mike: “Hi Ian, is it £99?”''<br><br />
<br><br />
Yep. It was £99 from Amazon. https://www.amazon.co.uk/gp/product/B015GDDXJA<br />
<br>I've done the full mechanical assembly, and knocked off for the night *WITHOUT* starting any wiring.<br><br />
<br><br />
For anyone else contemplating this one, beware: the rails are steel tube, not rod, it has plastic slider bushings not linear bearings, and the Z drive nuts are aluminum, not bronze or brass. Also the filament drive is not adjustable for pressure, and there are very few free GPIOs on the controller available for custom stuff. (There's the three SPI pins of the ISP port J3 ''if you disable SD card support'', one pin on the LCD connector reserved for a beeper on some display boards, and I suppose you could free up two more analog capable pins and UART1 TX & RX if you added an I2C LCD driver board.)<br><br />
<br>[[File:Ian's CTC I3 IEC Boot + extra clamping nuts on Y strut.jpg|thumb]]<br />
* '''CAUTION: THERE ARE EXPOSED MAINS TERMINALS'''<br><br />
As soon as I've got it dialled in I need to print a cover for the back of the IEC connector, and do something better than the flip-up cover over the PSU mains terminals. ''I ended up putting a rubber boot made from bicycle inner tube over the back of the IEC connector secured with cable ties as it was just too unsafe adjusting the right rear bed levelling screw without insulation there.'' <br><br />
<br><br />
I've already improved the rigidity considerably by adding four M8 nuts and washers to clamp the vertical frame to the M8 allthread that joins the front and back end plates. If you do the same, you *MUST* align the frame and endplates on a dead flat surface<sup>'''*'''</sup>, and as you tighten the new nuts, use a straightedge to check you aren't bowing the vertical frame's lower cross-member. Check you get the front on again dead square. While you are in there, put a nut in the hex hole in the Y axis belt tensioner so the bolt stays put while you adjust the wing nut.<br><br />
<br><br />
I'm sure I'll be buying other bits for it, once its up and running. e.g. flexible couplings + bearing balls for thrust for the Z screws to reduce shimmy, cheap but real linear bearings, and an all metal adjustable pressure filament drive upgrade kit.<br><br />
<br><br />
'''''<nowiki>*</nowiki> The flatness of the assembly surface is crucial - 0.2 mm lift of one side of the front plate relative to the rest of the frame, becomes 0.1 mm of varying bed tilt as the bed moves from min. Y to max. Y or visa-versa, giving the illusion the bed surface is saddle shaped, but also resulting in increasing lateral distortion the greater the print height is above the bed rails. Once assembled flat and true, it *should* be operated on an equally flat surface to maintain alignment, but if your table is of questionable flatness, the printer can be shimmed under its frame, and front and back plates to maintain six points of contact, and its position on the table marked to remind you to keep it in the position you've shimmed flat for it.''''<br><br />
<br><br />
<br />
=== 9 Jan 2022 - Wiring and problems ===<br />
Doing the CTC I3 3D printer wiring neatly took most of Saturday afternoon. Then it didn't work! 😢<br><br />
''Back in January, the extra board above the main board (to combine the normal Z limit switch and the BLtouch probe output), and all wiring to it was not present, and only the standard single short-lever Z limit microswitch was fitted.''<br />
[[File:Ian's CTC I3 Boards and Wiring.jpg|thumb|The main board and wiring]]<br />
<br><br />
Diagnosing its ills took the whole evening - one of the Z steppers had a broken wire. After carefully teasing the offending pin out of the stepper cable connector, I cleaned out the old crimp and soldered it and both steppers stepped uncoupled. It helps to use a couple of M8 nuts, put on the tops of the Z screws to hold them up so the X axis doesn't have to be dismantled when working on the Z steppers and couplings. The left side was binding and the right side wasn't a whole lot better. Turns out the laser cut bracket motor mounts don't line up with the screw when the Z axis is near the bottom. It’s fiddly but it is possible to remove the motors without extra dismantling. Some careful filing to elongate the mounting holes to line up the motor and final tightening after the coupling was slid over the screw end, and it no longer binds.<br> <br />
<br><br />
However, it still failed to home. 😾 Investigating the limit switch signals found the odd one out was the Y axis which read as homed when it wasn't. The switches are all NC microswitches, and I was getting ready to replace it, when I found its connections failed the tug test on both wires! The wires were broken under enough OEM heatshrink to confuse the issue. Resoldering them and applying new heatshrink fixed that and it now homes.<br><br />
<br><br />
I suspect the motor wire was a bad crimp, and the switch wires most likely broke because they were 'flapping in the breeze' while the bed, Y axis and lower frame assembly was being packed and shipped.<br><br />
<br><br />
Finally I was able to test the full range of motion of all axes, do a quick & dirty manual bed levelling and set the Y zero limit screw as low as seems reasonable. (I had it high to avoid crashing the nozzle earlier.) Selecting PLA warmup showed both the heated bed and the hot-end were working, and stabilized at their setpoints, though I'm getting an initial 10 deg C overshoot during hot end warmup, so it probably needs some tuning.<br><br />
<br><br />
I then tried to load and feed filament - no joy - it didn't want to feed, and when I manually encouraged it all I got for my trouble was a clogged hot-end. Taking the extruder off, dismantling it and careful reassembly of the feeder got it feeding, but I still had the clog to deal with.<br> <br />
<br><br />
I suspected the PTFE tube liner in the heat-break wasn't seating properly, which is what probably caused both the feed problem and the clog. I dismantled the hot-end and extracted the PTFE tube - clogged solid and fatter than the throat at the top of the heat-break tube. I managed to press the clog out with the stem of an Allen key, then close inspection of the PTFE tube found neither end was square. I shaved the better end square, and chamfered the entry to the other end by twiddling a sharp drill bit to stop the filament catching on its edge. Clearing the nozzle was a PITA, eventually it succumbed to a cold pull done off the hot end, supporting the nozzle with a small ring spanner and heating it with a lighter.<br><br />
<br><br />
I then bench tested the extruder, and it now feeds and extrudes, (manually using the axis menu). Its really fiddly to bolt back on to the X carriage without stripping it to separate the bracket, but after a lot of faffing about and some rather unparliamentary language I got it back on properly, leaving it loaded with filament from the bench test.<br><br />
<br><br />
Finally I checked it still homes and that the bed levelling hadn't gone too far out while I was working on it, and shut it down for the night.<br><br />
<br><br />
ToDo: Try printing something!<br><br />
<br><br />
<br />
=== 9 Jan 2022 - Q&A with Ian B, dangerous mains plug, and sellers 'bait & switch'! ===<br />
''Ian B: “Ian, that's quite a log of problems solved. It certainly shows a lack of QC from the manufacturer.''<br><br />
<br><br />
''It seems you've approached each fault methodically. (I would expect nothing less from you.) Heating the extruder with a lighter is something I've never heard of before, useful technique.''<br> <br />
<br><br />
''I wish you luck with the first print. Keep it small and simple.''<br><br />
<br><br />
''Then I wish you ongoing luck with all subsequent prints, too.”''<br><br />
<br><br />
If you try my lighter trick, to avoid bouncing a hot-ish nozzle round the room, it would probably be a better idea to screw the nozzle into a M6 nut, and hold it in mole grips with card for thermal isolation from the grips, and clamp the grip handles flat in a vice. The nut will also increase the thermal mass making the whole process more controllable.<br><br />
<br><br />
I forgot to mention the illegal ('The Plugs and Sockets etc. (Safety) Regulations 1994' - UK Statutory Instruments 1994 No. 1768) undersized and unfused mains plug on its supplied IEC lead. Its pins were so far undersize that there was no retention force in a standard socket!<br><br />
<br><br />
John Ward on these counterfeit leads & plugs: https://www.youtube.com/watch?v=9KMrWupFQt4<br />
<br><br />
AITA if I try to nail Amazon's balls to the wall for "not as described" and the illegal mains lead? It was still a reasonably good deal as supplied . . .<br><br />
<br><br />
==== Description from Amazon product page at time of sale ====<br />
* Brand Josef Prusa<br />
* Material Carbon Fibre<br />
<br />
'''Product description - Technical specifications'''<br />
* Print area - 8x8x8 inches (20x20x20 cm)<br />
* Open frame design for easy use<br />
* Integrated LCD for use without a computer<br />
* SD card support (8GB included) and USB port<br />
* Geniune E3D 1.75mm hotend and RAMBo mini motherboard<br />
* Easy multicolor printing feature based on layer height<br />
* Layer height from 50 microns<br />
* Heated print bed for warpless printing from any material<br />
* Supported materials - PLA, ABS, PET, HIPS, Flex PP, Ninjaflex, Laywood, Laybrick, Nylon, Bamboofill, Bronzefill, ASA, T-Glase, Carbon-fiber enhanced filaments...<br />
* Step size in X/Y axes - 10 micron<br />
* 2 lbs (1 kg) Silver PLA included<br />
<br />
==== DISCREPENCIES (so far) ====<br />
* Not a genuine Josef Prusa printer - its a ZHUHAI CTC ELECTRONIC CO. model.<br />
* Plywood frame, and no carbon fibre components<br />
* Less than 20cm X travel - measured 18.6cm from mechanical limit to limit<br />
* No SD card supplied<br />
* Not a "Geniune (sic) E3D 1.75mm hotend" - its got a bargain basement generic clone hotend<br />
* Not a "RAMBo mini motherboard" - its got an Anet A8 v1.5 clone, with a lesser MCU, no max. endstop switch inputs, one less thermistor input, and only three PWMed MOSFETs, so only one controlled fan can be connected.<br />
* No "2 lbs (1 kg) Silver PLA included" - Three sample coils of approx 12m each, total under 120g supplied<br />
<br />
=== 12 Jan 2022 - First Print and another defect found ===<br />
The CTC I3 3D printer prints!<br><br />
<br><br />
I'm currently using Cura 3.2.1, and so far have done a test cube and am currently trying an Arduino Mega2560 'bumper' generated from an OpenSCAD library. I aborted the first run after a couple of layers to have something to check against the Arduino board - it looks reasonable, so I'm doing a proper run, and hoping it comes out well enough to use. <br><br />
<br><br />
More defects found! The X tensioner bolt has a really crappy rolled thread and wont hold in the wing-nut. An ordinary M3 nut on it has just enough grip to be usable. I need to replace it with a long M3 machine screw, so I can get a nut into the tensioner body to hold it, so it doesn't spin when I adjust the wing nut. ''Subsequently fixed with a length of M3 stainless allthread, with the end mushroomed slightly and a hex nut Loctited on flush to effectively make that long machine screw.''<br><br />
<br><br />
Next job will be to see if I can backup the existing firmware then look at what it takes to get Marlin built for an Anet A8 v1.5 controller, and configured for the CTC I3 3D. Once I've got a usable 'stock' firmware, I can look at the upgrades I want to do, as even swapping out the extruder's filament drive mechanism would need me to reverse the extruder motor (due to the handedness of the drive assembly required to clear the mounting bracket). ''I did succeed in making a backup using AVRDUDE and a PICkit 2.''<br><br />
<br><br />
Edit: The Arduino 'bumper' is usable - a bit tight, so either my X and/or Y scaling is fractionally off or the Elegoo Mega2560 clone PCB is fractionally oversize.<br><br />
<br />
=== 17 Jan 2022 - Running my own Marlin build and finding/fixing more mechanical defects ===<br />
Progress of a sort on the CTC DiY I3 3D printer . . .<br><br />
<br><br />
The stock firmware is fairly sucky, ''probably doesn't have thermal runaway protection,'' and CTC don't appear to have released their source :( so I've been working on configuring a Marlin 1.1.9 build to run on it. Its only got an ATmega1284P ''(which has 128K Flash program memory)'', and I'm currently at 95% used, so Marlin 2.0.x isn't really a good option as I'd have to pare it down too much. Unfortunately those who have been there before me had a DiY I3 with a different controller so its been a fight to hack the config files into a usable state for it. I've still got some FUBARed Z motion defaults I need to sort put before it tries to get the Z axis to dig for Australia again! Maybe I should restore the backup of the original firmware and time some motions . . .<br><br />
<br><br />
In other news, there is supposedly no calibration table for its thermistors that's usably close, so I've had to generate one fudged from an Excel spreadsheet and some dodgy temperature measurements taken with a 1N914 diode stuffed up the hot end<br><br />
''My life was complicated here by the lack of any thermometer that could survive hot end temperatures.''<br> <br />
<br><br />
Bed Levelling needs some work, I'm trying to get manual mesh levelling up and running but it really *HATES* concave beds, as there is no option to automate moving to a safe height to clear the edge after homing off the edge of the bed. Various kludgy firmware hacks have been proposed, but I think a hardware hack is in order - use the Ymin limit switch to switch in a different height Zmin limit switch when its not over the bed, so it can be adjusted to home at a height that skims just clear of the [0,0] bed corner, then can go -Z by up to a mm or so before the regular Zmin limit trips, to allow it to level mesh points 'in the valley' without a Z probe.<br><br />
<br><br />
To that end, has anyone got a *looooooooong* lever SPDT microswitch hanging about? Flat lever and 20mm 2 hole body with terminals on the bottom preferred. Also, ideas for a cheap-skate Z probe wouldn't go amiss.<br><br />
<br><br />
''In the end I found some suitable switches on Amazon and built my dual switch Z axis limit 'Z-hop' mod. It fits in place of the original switch and if homing, with the nozzle just off the front of the bed provides a Z limit a little over 0.5mm higher than that over the bed, with the difference adjustable by bending the long switch lever. Some months later I found a BLtouch Z probe clone far cheaper than I could build any sort of deployable probe.''<br><br />
<br> <br />
Also, has anyone got experience automating acquiring temperature calibration table data for Marlin? I'm thinking maybe a Type K thermocouple bonded into a knackered brass extruder nozzle with high temperature cement, and some sort of PC interface for it, talking to Marlin with M105 SHOW_TEMP_ADC_VALUES enabled. Take it up in steps, reading the ADC and temperature for each till its good & hot, then log the cooling curve and check it matches reasonably well, and finally spit out a table in Marlin header file format.<br><br />
<br><br />
* '''CAUTION: Belt tensioners destroy themselves!'''<br />
The idiots at CTC used D shaft offcuts for the belt tensioner pully shafts and used the drive type pully for the idlers so the shaft turns with the pully. Running in a plastic hole with no bushing it acts as a D reamer and tries to chew its way back to the motor! A reasonable bodge fix is to flatten four M5 split washers ''(two for each tensioner)'', and wedge them in the recesses either side of the tensioner body, with the splits towards the tension screw. That's steel on steel, but if kept greased is better than steel D reamer on plastic! Long term it needs decent ball bearing tensioners. ''[[#18 June 2022 - Upgrading the belt tensioners with ball bearings|See below.]]<br><br />
<br />
=== 20 Jan 2022 - Flexible Z screw couplers ===<br />
The original rigid couplers between the Z stepper motors and the Z screws were unsatisfactory, as any misalignment directly pushed the gantry laterally resulting in prints with pronounced Z banding. I therefore bought some helical flexible couplers for coupling 5mm to 8mm shafts, and installed them with a 7mm ball bearing inside each to transfer the axial thrust loading from the Z screws direct to the motor shaft to minimize Z bounce. I had to shim the lead screws (which are ordinary M8 allthread) with aluminum cut from a drink can to get them concentric in the 8mm end of the coupler as their OD is slightly undersize.<br />
<br />
Although there was a notable improvement in print quality once I had carefully adjusted the coupler alignment, it wasn't a total cure as the lead screws are still shimmying enough to wobble the gentry at low Z heights. I need to decouple the drive nuts from the gantry, by flipping them the other way up and adding a thrust bearing that doesn't constrain them radially between them and the gantry. The nuts will also require anti-spin arms, and as the screws will no longer have any constraint above the couplers, they'll need top bearings.<br />
<br />
I also added a silicone 'sock' over the hotend to improve its insulation and reduce the hot touch hazard to just the nozzle itself.<br />
<br />
=== 10 Feb 2022 - Upgrades ===<br />
CTC DiY I3 3D printer progress: All slider bushings have been replaced with real linear bearings and I'm now printing a 3DBenchy in black PLA on 1.8mm glass (cut from a broken picture frame), with cooling<sup>'''*'''</sup>, using Cura 3's 'stock' slicer settings: Fine (0.1mm layers, 20% infill). So far its looking good.<br><br />
<br><br />
I need to do something about a proper enclosure for it as the ambient temperature is a bit on the low side.<br><br />
''Currently its in a cardboard enclosure made from a very large cardboard Amazon box, with a thin plastic sheet curtain front. This is a fire risk, and replacement with a non-combustible enclosure (e.g. made from plaster wallboard) or flame-retardant enclosure should be a high priority. Unfortunately running without an enclosure isn't a good option due to the number of print failures I've had due to warping caused by drafts resulting in loss of bed adhesion.''<br><br />
<br><br />
'''''<nowiki>*</nowiki> I added a 50mm centrifugal part cooling fan, stuck onto the back of the extruder motor using 3M (clone) VHB tape, with a thin aluminum tapered duct aiming at the extruder nozzle. This fan is connected to the only software controlled fan port on the Anet3D controller - FAN1. (FAN2 is permanent 12V, used for controller board cooling.) The extruder cooling fan is now wired in parallel to the hot-end heater. ToDo: design and build an extruder fan run-on circuit so sit starts when the heater is first activated, then continues to run to keep the top of the heat-break cool till the hot-end is below 100°C (or maybe simply a retriggerable timer of several minutes).''''<br><br />
<br />
=== 13 Feb 2022 - Running out of program memory! ===<br />
I just managed to build Marlin v1.1.9 with UBL (unified bed levelling) to fit in a ATmega1284P (ANET 3D v1.5 board).<br><br />
<br><br />
Will I be using it? That's a hard *NO* because to get it to fit I had to disable just about everything else except thermal protection and minimal LCD menus. No SD support, no emergency parser, no cold extrusion prevention, no endstop interrupts, no G26 mesh validation print, no M503 and a host of other minor snips and vicious GCC size optimizations. I even rewrote the Arduino LiquidCrystal library with no 8 bit support to save another hundred bytes. Also it wont fit with *any* bootloader so the only option would be to use an AVR programmer and ISP. :(<br><br />
<br><br />
''Ian B: Seems that the ANET 3D board is seriously under-spec with that processor. It wouldn't have cost them much to fit a processor with bigger ROM.''<br> <br />
''Anyway, some say UBL is all it's cracked up to be. Just get your build plate physically level, as I'm sure you have.''<br><br />
(I suspect Ian B meant: "... UBL '''isn't''' all it's cracked up to be.")<br><br />
<br><br />
''Petr Cecil: Check the bigtreetech boards on the AliExpress I had one for about 12 quids in some sale, still running on it my ender 3''<br><br />
''They got much more memory''<br><br />
<br />
=== 16 Feb 2022 - More musings on bed levelling and program memory ===<br />
I was just looking at my options before building a Z probe. I've already got manual bed levelling with a 5x5 grid installed without disabling SD support or anything else nice to have, so I've just got to look at alternatives to full UBL. e.g. switch ''(from UBL)'' to AUTO_BED_LEVELING_BILINEAR with no other changes and it goes from needing 100% + 410 bytes more (than optiboot max user progmem) to only 62%, so I should be able to turn SD support back on + most of the nice stuff I pruned. Although a more capable controller would be *nice*, this *IS* only a £99 3D printer so its hard to justify spending for a good controller before I've even got all the mechanicals up to scratch.<br><br />
<br><br />
''My 3D printer build was then on hiatus for several months. I did do a couple of non-notable successful prints on its (questionably) manually leveled bed, and spent a fair bit of time teaching myself OpenSCAD.''<br />
<br />
=== 18 June 2022 - Upgrading the belt tensioners with ball bearings ===<br />
Previously:<br />
<blockquote><br />
* '''CAUTION: Belt tensioners' destroy themselves!'''<br />
The idiots at CTC used D shaft offcuts for the belt tensioner pully shafts and used the drive type pully for the idlers so the shaft turns with the pully. Running in a plastic hole with no bushing it acts as a D reamer and tries to chew its way back to the motor! A reasonable bodge fix is to flatten four M5 split washers ''(two for each tensioner)'', and wedge them in the recesses either side of the tensioner body, with the splits towards the tension screw. That's steel on steel, but if kept greased is better than steel D reamer on plastic! Long term it needs decent ball bearing tensioners.<br><br />
<br><br />
''[[#17 Jan 2022 - Running my own Marlin build and finding/fixing more mechanical defects|Ref: 17 Jan 2022 - finding/fixing more mechanical defects]]''<br />
</blockquote><br />
[[File:CTC Tensioner.png|thumb|Belt Tensioner]]<br />
Well I finally got and fitted MR85ZZ ball bearings to both belt tensioners on my CTC DiY I3 3D printer. The bearings are ludicrously tiny, 8mm OD, 5mm ID and only 2.5mm thick, which is only 1.5mm radially for both races and the balls between them, but that's what it takes to fit the bearing recess either side of CTC's 'factory' belt tensioner. Each bearing is held in its seat by a M3 screw next to the outer race, so they aren't going anywhere. I loctited the D shaft into the front X tensioner bearing so I shouldn't have any more failed prints due to it walking out of the idler pully.<br><br />
<br><br />
For anyone else contemplating the Zuhai CTC DiY I3, I couldn't find a STL (or any other model) of the tensioner anywhere, which as supplied is a wear part, and a rapidly wearing one at that, as the D shaft will chew the holes badly out of round in only a few hours printing unless you mod it so it isn't running edged steel on plastic, so (as usual) I modelled it in OpenSCAD, taking the dimensions as accurately as I could from the 'factory' tensioner. Get the tensioner model here: [[File:Tensioner4.zip]]<br><br />
<br />
=== 25 June 2022 - Testing a BLtouch probe ===<br />
<br />
I'm (slowly) working on adding auto bed levelling to my CTC DiY I3 3D printer.<br><br />
Here's an Arduino sketch to bench test a BLtouch/3Dtouch (or clone) levelling sensor, that lets you set probe states by single letter serial commands and reports the ZMIN output status, like this:<br><br />
<br />
*** BLtouch/3Dtouch probe tester ***<br />
D = Deploy<br />
T = Tswitch<br />
R = Retract<br />
S = Self test<br />
A = Alarm off<br />
? = read ZMIN<br />
The Arduino LED echoes the ZMIN state, ON=High / OFF=Low<br />
__________________________________________________________________<br />
________________#___________________________________#_#___________<br />
____________________###______####_______##########_________####___<br />
____####__________________________________<br />
ZMIN is Low (0.10V)<br />
____________________________######################################<br />
ZMIN is High (5.00V)<br />
#################_________________________________#_______________<br />
<br><br />
The sketch: [[File:BLtouch tester.zip]]<br />
<br />
=== 29 June 2022 - Mounting the BLtouch, and building Marlin to support it ===<br />
Slight progress on adding a BLtouch (clone) ABL sensor to my Zuhai CTC DiY I3, 3D printer. I've got the probe bracket printed and the BLtouch mounted on my printhead, with only 26mm Y offset, and nearly no X offset, without blocking access to the top of the throat in case of filament problems.<br><br />
<br><br />
''I drilled two 3mm holes just in from the front edge of the L bracket that holds the print head assembly to the X gantry carriage, in front of the mounting block that holds the hotend, to fix the bracket to with 2.5mm self-tappers from underneath into the printed probe bracket. My bracket was a little too low for the optimum probe height relative to the nozzle tip (above the tip by half the probe extension), so I ended up shimming it with a piece of wooden coffee stirrer. Once I touched it in with a black marker, you wouldn't know the shim is there, so although I fixed my OpenSCAD' bracket model, I'm going to be lazy/frugal and not re-printt it'<br> <br />
<br><br />
My printer uses an ANET3D v1.5 controller, so I've only got 128K FLASH on the ATmega1284P MCU to play with (half that on the usual ATmega2560 based boards), which has made building Marlin 1.1.9 small enough to fit with AUTO_BED_LEVELING_BILINEAR and BLTOUCH enabled quite a challenge.<br><br />
Even with aggressive GCC optimizations, (see links section below) it didn't quite fit until I disabled the boot screen. It was a choice between that and ditching Optiboot. :( <br />
Sketch uses 129932 bytes (99%) of program storage space. Maximum is 130048 bytes.<br />
Its a 'full fat' Marlin v1.1.9, with full menu, SD support and all the other nice to have goodies enabled., and I've still got 116 bytes left for any tweaks I want to add! 😁 <br><br />
<br><br />
''Petr Cecil: Just keep important features like thermal runaway protection on in marlin so you don't burn your home :))''<br />
<br />
''Yes, keeping thermal runaway protection was my highest priority. Without it, you are one loose screw away from a house fire! Many thanks to Petr for letting me use his crimper and JST connector parts to make up a JST XH-3 cable I badly needed for my BLtouch install. For anyone else needing JST XH (and duPont) crimping capability, here's what Petr recommends:'' <br />
https://www.amazon.co.uk/gp/product/B07VX6YGQ8/ ''and having used it, I would also recommend it.''<br><br />
<br />
=== 1 July 2022 - Wiring the BLtouch probe ===<br />
I've got most of the recabling done on my CTC DiY I3 for the BLtouch probe. I've spliced a three wire breakout cable for +5V Gnd and servo signal into my display ribbon cable, and re-done the loom to the printhead to add the BLtouch extension cables. All that's left to do is assemble the adapter board that Petr helped me with the JST cable for, mount and wire it, flash a BLtouch enabled Marlin build, and then I'll need to calibrate the Z offset.<br><br />
<br><br />
[[File:BLtouch combiner board.png|thumb]]<br />
... and here's the circuit I intend to use to combine use of the regular limit switch which is set up to inhibit Z movement approx half a mm below the bed surface (less than the flex in the gantry) so it cant 'dig for Australia' if for any reason the BLtouch wasn't deployed before homing.<br><br />
<br><br />
''I constructed the combiner board on Veroboard, laying it out using [https://veecad.com/ VeeCAD], from the schematic I drew up in [https://www.tinycad.net/ TinyCAD], mounted it to the printer and wired it up.''<br />
<br />
=== 5 July 2022 - Visualizing the bed levelling mesh ===<br />
Meanwhile, I've been futzing around with visualising 3D printer bed levelling meshes from Pronterface *without* pasting the M420 V mesh data into a website. Marlin comes with an OpenSCAD mesh visualiser called [https://github.com/MarlinFirmware/Marlin/blob/1.1.x/buildroot/share/scripts/MarlinMesh.scad MarlinMesh.scad], and it turns out that all you need to do to get external mesh data into that is to pass it in on the OpenSCAD command line as variables defined by -D override variables with file scope defined in the file. <br />
<br />
The prerequisites for using it are explained here, but if you've already got OpenSCAD installed and are using mesh bed levelling, you'll only need to skim this: https://3dwork.io/en/visualize-3d-mesh/<br />
<br />
To do this from Pronterface, with a hard coded mesh, as I hadn't figured out the M420 mesh parsing yet, put MarlinMesh.scad in the printrun directory and (on windows) in Pronterface send:<br />
<br />
!os.system('start /max "" "C:\Program Files\OpenSCAD\openscad.exe" MarlinMesh.scad -D $vpd=800 -D measured_z= <br />
[[-0.086,-0.045,-0.037,-0.046,-0.167,-0.292,-0.421],[+0.034,+0.038,-0.002,+0.017,-0.017,-0.121,-0.413], <br />
[+0.122,+0.098,+0.162,+0.034,-0.069,-0.234,-0.472],[+0.205,+0.196,+0.120,+0.071,-0.007,-0.149,-0.467], <br />
[+0.175,+0.174,+0.102,+0.010,-0.130,-0.313,-0.587],[+0.194,+0.189,+0.116,+0.034,-0.042,-0.170,-0.568], <br />
[+0.128,+0.089,+0.032,-0.033,-0.168,-0.373,-0.594]]')<br />
<br />
Note that this is currently Windows only, as the os.system() command string to launch OpenSCAD and return immediately:<br />
'start /max "" "C:\Program Files\OpenSCAD\openscad.exe" '<br />
will be very different under LINUX or OSX. The rest of the command line should be the same.<br />
<br />
Also I would strongly recommend editing the default mesh in MarlinMesh.scad (lines 24-30) to be a minimal 'null' mesh:<br />
measured_z=[[0,0],[0,0]]; //minimal mesh<br />
to make it obvious if your mesh data hasn't been passed in successfully.<br />
<br />
ToDo: Write a script to send G420 V to the printer and parse the returned mesh data into a string containing the mesh in the above OpenScad list of lists format, that can simply be appended to the os.system() command line after the -D measured_z=<br />
<br />
''Later that evening:''<br><br />
I've written and tested the Pronterface macro to launch MarlinMesh.scad from Pronterface with the printer's current MBL mesh from a M420 V report of the form:<br />
Bilinear Leveling Grid:<br />
0 1 2 3 4 5 6<br />
0 -0.086 -0.045 -0.037 -0.046 -0.167 -0.292 -0.421<br />
1 +0.034 +0.038 -0.002 +0.017 -0.017 -0.121 -0.413<br />
2 +0.122 +0.098 +0.162 +0.034 -0.069 -0.234 -0.472<br />
3 +0.205 +0.196 +0.120 +0.071 -0.007 -0.149 -0.467<br />
4 +0.175 +0.174 +0.102 +0.010 -0.130 -0.313 -0.587<br />
5 +0.194 +0.189 +0.116 +0.034 -0.042 -0.170 -0.568<br />
6 +0.128 +0.089 +0.032 -0.033 -0.168 -0.373 -0.594<br />
echo:Bed Leveling Off<br />
echo:Fade Height Off<br />
<br />
[[File:Bed mesh.png|thumb|My poor bed looks like a map of the Himalayas!]]<br />
So I've now got a Pronterface button that visualizes my bed live, without resorting to an online bed visualizer WWW site. 😁<br />
<br />
''Even with ABL enabled, its useful to let you see if your whole bed is out of whack' and could benefit from adjusting its levelling screws to reduce the range of Z offsets the ABL has to compensate for.'' <br />
<br />
It is currently Win x64 only, as the command line to launch OpenSCAD is OS specific. It shouldn't be hard to change that for Linux or OSX.<br />
<br />
To add it to your own Pronterface, first put MarlinMesh.scad in your Printrun folder, then paste the following into a new Pronterface macro:<br />
<pre><br />
!################# Bed Visulization macro #################<br />
!# Pronterface script to invoke OpenSCAD MarlinMesh with #<br />
!# the current MBL mesh returned by M420 V. #<br />
!# #<br />
!# (c) Ian.M 7/7/2022 #<br />
!# #<br />
!# "THE BEER-WARE LICENSE" (Revision 42): #<br />
!# "Ian.M" <https://t.me/Ian_M_2019> wrote this stuff. #<br />
!# As long as you retain this notice you can do whatever #<br />
!# you want with this stuff. If we meet some day, and #<br />
!# you think this stuff is worth it, you can buy me a #<br />
!# beer in return. Ian.M #<br />
!##########################################################<br />
!<br />
!import time<br />
!import os<br />
M420 V ; requst ML grid<br />
!time.sleep(1) # wait for it<br />
!idx=len(self.p.log)-1 # get last line in log buffer<br />
!idxf=None # error value <br />
!idxl=None<br />
!for x in range(idx,max(idx-20,0),-1): # iterate backwards <br />
! if self.p.log[x].find("Grid:")>8: # looking for 'Grid:', if found:<br />
! idxf=x+2 # set idxf to first (real) line of grid <br />
! break; # and exit loop<br />
! if self.p.log[x].find("echo:")==0: # looking for 'echo:', if found:<br />
! idxl=x-1 # set idxl to previous line till last line of grid is found<br />
!<br />
!#print("Debug: range "+str(idxf)+", "+str(idxl))<br />
!<br />
!if (idxf is None) or (idxl is None): # M420 failed<br />
! self.logError("Error: M420 failed")<br />
! return<br />
!if idxf>idxl: # M420 no grid<br />
! self.logError("Error: M420 did not return a grid")<br />
! return<br />
!<br />
!mesh="["<br />
!for x in range(idxf,idxl+1): # build list of OpenScad lists<br />
! mesh=mesh+"["+str(self.p.log[x])[3:].rstrip().replace(" ",",")+"]" # build comma separated list<br />
! if x<idxl:<br />
! mesh=mesh+"," # more to follow<br />
! else:<br />
! mesh=mesh+"]" # last one - end outer list<br />
!<br />
!# Build MMcmd for OpenSCAD installed in default location on 64 bit Windows.<br />
!# N.B use explicit 64 bit Program Files directory as Pronterface is a 32 bit application,<br />
!# so %ProgramFiles% returns %ProgramFiles(x86)%, which is the wrong folder.<br />
!MMcmd='start /max "" "%ProgramW6432%\\OpenSCAD\\OpenSCAD.exe" ' # change this OS dependent stuff!<br />
!MMparams="MarlinMesh.scad -D $vpd=800 -D measured_z=" # OpenSCAD command line parameters<br />
!# n.b. MarlinMesh.scad must be in printrun working directory<br />
!# -D defines an OpenSCAD constant for the session, overriding variables within the file. <br />
!<br />
!print("Invoking MarlinMesh.scad with this mesh.")<br />
!print("Exec: "+MMcmd+MMparams+mesh)<br />
!os.system(MMcmd+MMparams+mesh) #Execute it<br />
</pre><br />
<br />
''Edit: It turns out, that depending on your Pronterface version, you'll probably need to import '''os''' and '''time''' at the top of the macro. I've added them above.''<br />
<br />
=== 10 Sept 2022 - Z-screw wobble isolation ===<br />
Back in January I wrote:<br />
<blockquote><br />
The original rigid couplers between the Z stepper motors and the Z screws were unsatisfactory, as any misalignment directly pushed the gantry laterally resulting in prints with pronounced Z banding. I therefore bought some helical flexible couplers for coupling 5mm to 8mm shafts, and installed them with a 7mm ball bearing inside each to transfer the axial thrust loading from the Z screws direct to the motor shaft to minimize Z bounce. I had to shim the lead screws (which are ordinary M8 allthread) with aluminum cut from a drink can to get them concentric in the 8mm end of the coupler as their OD is slightly undersize.<br />
<br />
Although there was a notable improvement in print quality once I had carefully adjusted the coupler alignment, it wasn't a total cure as the lead screws are still shimmying enough to wobble the gentry at low Z heights. I need to decouple the drive nuts from the gantry, by flipping them the other way up and adding a thrust bearing that doesn't constrain them radially between them and the gantry. The nuts will also require anti-spin arms, and as the screws will no longer have any constraint above the couplers, they'll need top bearings.<br />
</blockquote><br />
<br />
At long last, I've completed the next stage of this, by laser cutting new top brackets and bearing retainers for 688ZZ ball bearings (8mm ID, 16mm OD, 5mm wide) from plywood, consisting of a redesigned bracket in 5mm ply, with a 16mm hole for the bearing which fits flush, surrounded by six tiny holes to fix retaining rings cut from 3mm ply above and below the bracket, each held by three tiny 2mm screws. I also laser cut the anti-spin arms for the Z-nuts from 5mm black Acrylic. All ply parts were spay painted matte black to match the rest of the printer frame. A Thursday evening well spent.<br />
<br />
I installed the parts and after some fiddling around managed to reduce the Z-screw runout, and got the screw centered well enough in the gantry end nut mounts not to touch and jerk. I still haven't got proper thrust bearings, and am making do with a stack of three M10 washers on the long end of each Z-nut, which have *NOT* been flipped as originally planned, as it looks like I'll need something other than the Z-screw to loosely constrain the thrust bearing. The washers are lightly greased so can slide over each other fairly readily<br />
<br />
After re-leveling (and some BLtouch calibration issues that were borking my first layer height), I finally managed to print a good test cube. Its got much less pronounced Z banding than before this upgrade. Hopefully adding ball thrust bearings will eliminate most of the residual banding. ToDo: design & fabricate cages for these bearings. The problem is a lack of space - I haven't got a lot of height between the top of the coupler and the bottom of the nut, and also, anything much larger than the 22mm OD of the nut flange would force me to move the part cooling fan and redesign its duct.<br />
<br />
''OpenSCAD design files and photos to follow''<br />
<br />
=== 06 January 2023 ===<br />
Another hiatus - I didn't need to do any 3D printing and was busy learning the RML mini-lathe.<br />
However I've made a small but significant improvement to the Z axis with nothing more than a few square cm of waxed paper! I took the backing paper off some double-sided tape, and wrapped one turn of the paper round the Z screw to make a spacer to fit inside the stack of washers. It sits over the lip on the end of the nut, inside the ID of the washer stack and helps the washer stack stay centered on the screw so none of them touch the screw, catch and jerk, but is so flimsy that the washers can still slide laterally with minimal extra force on the X gantry. A test cube showed much reduced Z banding vs the previous one from October.<br />
<br />
Its still not good enough as there is far too much runout at the bottom of the right-hand lead-screw which is shifting the X gantry support force to and fro enough to wobble it. Either I've got a bad coupler, its poorly assembled or there is a kink in the end of the screw where it was cut. Probably the best option will be to chuck the leadscrew in a soft collet in the lathe, get it running true, then turn the thread off the end of the leadscrew, shrink on a short bored out piece of steel rod, then turn that to 8.00 mm diameter, concentric to the screw, so I'm no longer trying to clamp on the threaded end.<br />
<br />
=== 13 December 2023 - Better Leadscrew Concentricity ===<br />
Some 3D printing of small parts this year, and several false starts with improving the lead screws. I spent quite a bit of lathe time doing test pieces with short lengths of M8 allthread. <br />
<br />
The soft collet idea was a non-starter as anything that grips on the thread tips gives poor concentricity. It turns out the answer is to wind a helix of soft iron or mild steel wire that fits the thread and grip on that so the grip is on the flanks of the thread. Also, shrink fitting was a bust - the precision and surface finish required to make it work for such small parts is right at the limit of RML's capabilities, and the tiny thermal mass gives only seconds to fit it and a fraction of a second to slide it home. The answer was loctite + machining to a push fit. 11 mm long, ~5.6 mm bore steel sleeves were made from 3/8" (9.5 mm) stock, and the thread turned down to fit for ~11 mm from the screw end. We don't have good enough bore measuring capability at RML so a test plug was turned to fit drilled bore to get the diameter to work to. Loctite was applied to both surfaces and the sleeve tapped on firmly. The OD was then turned to 8.00 mm and faced to 10 mm length, just cleaning up the screw end to get a true uniform end face, and the edge chamfered. <br />
<br />
I've got one leadscrew done, but time and machining mistakes were against me (I screwed up the 8.00 mm OD and had to turn the sleeve off and re-do it) so didn't get the second screw done. That's a job for tomorrow. <br />
<br />
Fitting and removing the screws now requires top corner plate removal. Run the gantry right up and hang it from the frame, then run the Z-nuts and their anti-rotation arms back down. Undo the coupler and take off the corner plate. The guide rod can be lifted and the anti-rotation arm swung clear, then the bottom end of the screw can be lifted off and slid down and forward till it can be slid out of the gantry end. Refitting is the reverse of removal.<br />
<br />
I've already got the left Z screw fitted, and the result is no obvious runout. Its highly dependent on the tightening sequence of the lower part of the helical coupler as excessive pressure with the split clamp causes the D shaft to go off center, so that should be lightly snugged up then the grubscrew tightened firmly on the flat. The grubscrew must be well aligned with the flat. Turn the other Z motor shaft to turn the one being assembled for access to the screws, as the coupler initially wont be tight enough to turn the motor.<br />
<br />
=== 15 December 2023 ===<br />
I machined the other screw yesterday evening and fitted it this morning, again with no obvious runout. I did some manual levelling to get the bed as near true to the Y rails as possible and the X gantry true to the frame and hopefully to the bed, then started automatic bed levelling, stored the resulting map, and started printing an XYZ calibration cube. The vertical sides came out nicely with no repetitive Z banding, so it seems my Z wobble problems are solved. However the waxed paper liner in the greased washer Z decoupler is a PITA to reinstall if disturbed, so I still need to look at thrust bearings, with some way to keep the cage from fouling the screw.<br />
<br />
== - more to follow - ==<br />
<br />
== Some useful links ==<br />
* https://github.com/ralf-e/ANET-3D-Board-V1.0 - Schematic for an earlier version of the controller, near enough the same as the v1.5, and for the LCD2004 display/buttons board. Note that connector pinouts should be checked against the actual board before trusting them. e.g. I know the end stop connectors have pins 1 and 3 swapped vs the schematic.<br />
<br />
* http://lokspace.eu/anet-a8-wifi-mod/ - How to add printing over WiFi using an ESP-01 ESP8266 WiFi module and esp-link, by populating the Anet3D 'USB BLE' header + removing two zero ohm resistors. Level shifting is needed to get the 5V level ATmega TX pin down to 3.3V levels for the ESP8266 RX pin, hence the resistors on the carrier board. There's also no need for a USB UART adapter to flash the ESP8266, as the ANET main board has one of those. After dong the mainboard mod, simply take two short duPont F-F jumpers and link opposite corner pins of J8 the 'USB BLE' header, and use the mainboard's USB port. After flashing, remove the duPont wires, fit two jumper caps in the BLE position, and carry on with esp-link setup. Alternatively, use a Wemos D1 Mini clone which has all you need on-board except the level shifter, and its simple enough to solder two resistors for that. See my page [[WiFi 'tethered' Arduino robot]]<br />
<br />
* https://docs.arduino.cc/software/ide-v1/tutorials/PortableIDE - how to set up a portable install of the classic Arduino IDE which is strongly recommended for any existing Arduino user for building Marlin 1.1.x as you are likely to need to down-version the core and various libraries.<br />
<br />
* https://spiritdude.wordpress.com/2018/03/26/ctc-diy-prusa-i3-ctc-diy-i3-pro-b-most-affordable-3d-printer-2018/ - Another user's experiences with this printer.<br />
<br />
* https://ufj.ddns.net/blog/marlin/2019/01/07/reducing-marlin-binary-size.html - Turning on aggressive AVR GCC optimizations to reduce the size of the Marlin firmware, so it will fit in 128K program memory without having to prune too many desirable features.<br />
<br />
* https://all3dp.com/2/epic-3d-printing-fails-and-why-they-failed/ - some of the many ways things can go badly, ranging from potentially life-threatening, down through expensive and tedious, to mildly amusing.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_%C2%A399_ZHUHAI_CTC_DiY_I3_3D_printer&diff=17598Ian M's £99 ZHUHAI CTC DiY I3 3D printer2023-12-15T10:24:03Z<p>IanM: /* 15 December 2023 */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br><br />
<br />
The ZHUHAI CTC DiY I3 Pro B 'Prusa' clone printer is rather similar to RML's [[Geetech I3 Pro B]] except with a laser cut plywood frame instead of acrylic, and cheapened in many key areas, which I'm working on upgrading. Its my personal 3D printer and is not kept at RML.<br />
[[File:Ian's CTC I3 After BLtouch upgrade.jpg|thumb]]<br />
== The DiY kit and the build ==<br />
Here's CTC's official build video: https://youtu.be/PSzcU48wczk<br />
=== Differences on my printer ===<br />
* IEC power inlet (Video has direct attached mains lead)<br />
* Bed levelling screws have countersunk heads so there are no obstructions at the bed corners<br />
<br />
=== Hints & Tips that didn't make it into the build log ===<br />
* Buy a pack of M3 washers and insert one in each T-slot in the frame, between the nut and the wood it bears on, to spread the pressure and prevent the nut chewing the wood.<br />
<br />
* A pair of M8 nuts can be used to 'hang' the lead screws and gantry assembly from the top of the frame while working on the steppers or shaft couplers.<br />
* Put a *VERY* large cable tie right round the body of the extruder and X steppers, with the tail coming straight up at the back of the extruder, and straight down off the X stepper, then cable tie the wiring to the big tail to anchor it before you spiral wrap, Leave the big tail full length inside the spiral wrap to stiffen the loom near the motor. A similar large cable tie round the lower right board fan standoff, snug but not tight so it can pivot on the standoff, can be used to anchor the lower end of the X loom.<br />
<br />
* The 2004 control/display PCB is probably being warped by its plywood frame and the absence of spacers between the board and the back not allowing for the solder joints with slightly protruding header pins. Dismantle it and shim for clearance behind the board with nuts/washers/etc. taking care not to short anything. You may need to file out the bolt holes in the ply so the board fits properly without being forced into a curve before reassembling and mounting it.<br />
<br />
== Build log from my posts on the RML Telegram group ==<br />
''Currently, a mostly verbatim copy of my 3D printer related posts, with some corrections and additions to my posts + some responses to my posts from other members. If you feel I've misrepresented what you said, or you don't want to be quoted, and you don't have edit rights here, PM me on Telegram!''<br><br />
<br><br />
''ToDo: Transfer more stuff from Telegram here and edit it into a coherent project writeup.''<br />
<br />
=== 6 Jan 2022 - Arrival and initial mechanical assembly ===<br />
A cheap (£99) Prusa i3 clone 3D printer kit should be landing on my doorstep later on this afternoon . . .<br><br><br />
{<s>photo from manual</s>, ''not posted here due to copyright''}<br><br><br />
It arrived.<br><br />
Its actually a ZUHAI CTC DiY I3 PRINTER with a wooden frame, and an ANET A8 v1.5 clone controller board. That’s more or less what I expected as a *real* Prusa for under a ton just isn't happening unless its a BER parts mule. Next: dig through the documentation, such as it is . . .<br><br />
<br><br />
''Mike: “Hi Ian, is it £99?”''<br><br />
<br><br />
Yep. It was £99 from Amazon. https://www.amazon.co.uk/gp/product/B015GDDXJA<br />
<br>I've done the full mechanical assembly, and knocked off for the night *WITHOUT* starting any wiring.<br><br />
<br><br />
For anyone else contemplating this one, beware: the rails are steel tube, not rod, it has plastic slider bushings not linear bearings, and the Z drive nuts are aluminum, not bronze or brass. Also the filament drive is not adjustable for pressure, and there are very few free GPIOs on the controller available for custom stuff. (There's the three SPI pins of the ISP port J3 ''if you disable SD card support'', one pin on the LCD connector reserved for a beeper on some display boards, and I suppose you could free up two more analog capable pins and UART1 TX & RX if you added an I2C LCD driver board.)<br><br />
<br>[[File:Ian's CTC I3 IEC Boot + extra clamping nuts on Y strut.jpg|thumb]]<br />
* '''CAUTION: THERE ARE EXPOSED MAINS TERMINALS'''<br><br />
As soon as I've got it dialled in I need to print a cover for the back of the IEC connector, and do something better than the flip-up cover over the PSU mains terminals. ''I ended up putting a rubber boot made from bicycle inner tube over the back of the IEC connector secured with cable ties as it was just too unsafe adjusting the right rear bed levelling screw without insulation there.'' <br><br />
<br><br />
I've already improved the rigidity considerably by adding four M8 nuts and washers to clamp the vertical frame to the M8 allthread that joins the front and back end plates. If you do the same, you *MUST* align the frame and endplates on a dead flat surface<sup>'''*'''</sup>, and as you tighten the new nuts, use a straightedge to check you aren't bowing the vertical frame's lower cross-member. Check you get the front on again dead square. While you are in there, put a nut in the hex hole in the Y axis belt tensioner so the bolt stays put while you adjust the wing nut.<br><br />
<br><br />
I'm sure I'll be buying other bits for it, once its up and running. e.g. flexible couplings + bearing balls for thrust for the Z screws to reduce shimmy, cheap but real linear bearings, and an all metal adjustable pressure filament drive upgrade kit.<br><br />
<br><br />
'''''<nowiki>*</nowiki> The flatness of the assembly surface is crucial - 0.2 mm lift of one side of the front plate relative to the rest of the frame, becomes 0.1 mm of varying bed tilt as the bed moves from min. Y to max. Y or visa-versa, giving the illusion the bed surface is saddle shaped, but also resulting in increasing lateral distortion the greater the print height is above the bed rails. Once assembled flat and true, it *should* be operated on an equally flat surface to maintain alignment, but if your table is of questionable flatness, the printer can be shimmed under its frame, and front and back plates to maintain six points of contact, and its position on the table marked to remind you to keep it in the position you've shimmed flat for it.''''<br><br />
<br><br />
<br />
=== 9 Jan 2022 - Wiring and problems ===<br />
Doing the CTC I3 3D printer wiring neatly took most of Saturday afternoon. Then it didn't work! 😢<br><br />
''Back in January, the extra board above the main board (to combine the normal Z limit switch and the BLtouch probe output), and all wiring to it was not present, and only the standard single short-lever Z limit microswitch was fitted.''<br />
[[File:Ian's CTC I3 Boards and Wiring.jpg|thumb|The main board and wiring]]<br />
<br><br />
Diagnosing its ills took the whole evening - one of the Z steppers had a broken wire. After carefully teasing the offending pin out of the stepper cable connector, I cleaned out the old crimp and soldered it and both steppers stepped uncoupled. It helps to use a couple of M8 nuts, put on the tops of the Z screws to hold them up so the X axis doesn't have to be dismantled when working on the Z steppers and couplings. The left side was binding and the right side wasn't a whole lot better. Turns out the laser cut bracket motor mounts don't line up with the screw when the Z axis is near the bottom. It’s fiddly but it is possible to remove the motors without extra dismantling. Some careful filing to elongate the mounting holes to line up the motor and final tightening after the coupling was slid over the screw end, and it no longer binds.<br> <br />
<br><br />
However, it still failed to home. 😾 Investigating the limit switch signals found the odd one out was the Y axis which read as homed when it wasn't. The switches are all NC microswitches, and I was getting ready to replace it, when I found its connections failed the tug test on both wires! The wires were broken under enough OEM heatshrink to confuse the issue. Resoldering them and applying new heatshrink fixed that and it now homes.<br><br />
<br><br />
I suspect the motor wire was a bad crimp, and the switch wires most likely broke because they were 'flapping in the breeze' while the bed, Y axis and lower frame assembly was being packed and shipped.<br><br />
<br><br />
Finally I was able to test the full range of motion of all axes, do a quick & dirty manual bed levelling and set the Y zero limit screw as low as seems reasonable. (I had it high to avoid crashing the nozzle earlier.) Selecting PLA warmup showed both the heated bed and the hot-end were working, and stabilized at their setpoints, though I'm getting an initial 10 deg C overshoot during hot end warmup, so it probably needs some tuning.<br><br />
<br><br />
I then tried to load and feed filament - no joy - it didn't want to feed, and when I manually encouraged it all I got for my trouble was a clogged hot-end. Taking the extruder off, dismantling it and careful reassembly of the feeder got it feeding, but I still had the clog to deal with.<br> <br />
<br><br />
I suspected the PTFE tube liner in the heat-break wasn't seating properly, which is what probably caused both the feed problem and the clog. I dismantled the hot-end and extracted the PTFE tube - clogged solid and fatter than the throat at the top of the heat-break tube. I managed to press the clog out with the stem of an Allen key, then close inspection of the PTFE tube found neither end was square. I shaved the better end square, and chamfered the entry to the other end by twiddling a sharp drill bit to stop the filament catching on its edge. Clearing the nozzle was a PITA, eventually it succumbed to a cold pull done off the hot end, supporting the nozzle with a small ring spanner and heating it with a lighter.<br><br />
<br><br />
I then bench tested the extruder, and it now feeds and extrudes, (manually using the axis menu). Its really fiddly to bolt back on to the X carriage without stripping it to separate the bracket, but after a lot of faffing about and some rather unparliamentary language I got it back on properly, leaving it loaded with filament from the bench test.<br><br />
<br><br />
Finally I checked it still homes and that the bed levelling hadn't gone too far out while I was working on it, and shut it down for the night.<br><br />
<br><br />
ToDo: Try printing something!<br><br />
<br><br />
<br />
=== 9 Jan 2022 - Q&A with Ian B, dangerous mains plug, and sellers 'bait & switch'! ===<br />
''Ian B: “Ian, that's quite a log of problems solved. It certainly shows a lack of QC from the manufacturer.''<br><br />
<br><br />
''It seems you've approached each fault methodically. (I would expect nothing less from you.) Heating the extruder with a lighter is something I've never heard of before, useful technique.''<br> <br />
<br><br />
''I wish you luck with the first print. Keep it small and simple.''<br><br />
<br><br />
''Then I wish you ongoing luck with all subsequent prints, too.”''<br><br />
<br><br />
If you try my lighter trick, to avoid bouncing a hot-ish nozzle round the room, it would probably be a better idea to screw the nozzle into a M6 nut, and hold it in mole grips with card for thermal isolation from the grips, and clamp the grip handles flat in a vice. The nut will also increase the thermal mass making the whole process more controllable.<br><br />
<br><br />
I forgot to mention the illegal ('The Plugs and Sockets etc. (Safety) Regulations 1994' - UK Statutory Instruments 1994 No. 1768) undersized and unfused mains plug on its supplied IEC lead. Its pins were so far undersize that there was no retention force in a standard socket!<br><br />
<br><br />
John Ward on these counterfeit leads & plugs: https://www.youtube.com/watch?v=9KMrWupFQt4<br />
<br><br />
AITA if I try to nail Amazon's balls to the wall for "not as described" and the illegal mains lead? It was still a reasonably good deal as supplied . . .<br><br />
<br><br />
==== Description from Amazon product page at time of sale ====<br />
* Brand Josef Prusa<br />
* Material Carbon Fibre<br />
<br />
'''Product description - Technical specifications'''<br />
* Print area - 8x8x8 inches (20x20x20 cm)<br />
* Open frame design for easy use<br />
* Integrated LCD for use without a computer<br />
* SD card support (8GB included) and USB port<br />
* Geniune E3D 1.75mm hotend and RAMBo mini motherboard<br />
* Easy multicolor printing feature based on layer height<br />
* Layer height from 50 microns<br />
* Heated print bed for warpless printing from any material<br />
* Supported materials - PLA, ABS, PET, HIPS, Flex PP, Ninjaflex, Laywood, Laybrick, Nylon, Bamboofill, Bronzefill, ASA, T-Glase, Carbon-fiber enhanced filaments...<br />
* Step size in X/Y axes - 10 micron<br />
* 2 lbs (1 kg) Silver PLA included<br />
<br />
==== DISCREPENCIES (so far) ====<br />
* Not a genuine Josef Prusa printer - its a ZHUHAI CTC ELECTRONIC CO. model.<br />
* Plywood frame, and no carbon fibre components<br />
* Less than 20cm X travel - measured 18.6cm from mechanical limit to limit<br />
* No SD card supplied<br />
* Not a "Geniune (sic) E3D 1.75mm hotend" - its got a bargain basement generic clone hotend<br />
* Not a "RAMBo mini motherboard" - its got an Anet A8 v1.5 clone, with a lesser MCU, no max. endstop switch inputs, one less thermistor input, and only three PWMed MOSFETs, so only one controlled fan can be connected.<br />
* No "2 lbs (1 kg) Silver PLA included" - Three sample coils of approx 12m each, total under 120g supplied<br />
<br />
=== 12 Jan 2022 - First Print and another defect found ===<br />
The CTC I3 3D printer prints!<br><br />
<br><br />
I'm currently using Cura 3.2.1, and so far have done a test cube and am currently trying an Arduino Mega2560 'bumper' generated from an OpenSCAD library. I aborted the first run after a couple of layers to have something to check against the Arduino board - it looks reasonable, so I'm doing a proper run, and hoping it comes out well enough to use. <br><br />
<br><br />
More defects found! The X tensioner bolt has a really crappy rolled thread and wont hold in the wing-nut. An ordinary M3 nut on it has just enough grip to be usable. I need to replace it with a long M3 machine screw, so I can get a nut into the tensioner body to hold it, so it doesn't spin when I adjust the wing nut. ''Subsequently fixed with a length of M3 stainless allthread, with the end mushroomed slightly and a hex nut Loctited on flush to effectively make that long machine screw.''<br><br />
<br><br />
Next job will be to see if I can backup the existing firmware then look at what it takes to get Marlin built for an Anet A8 v1.5 controller, and configured for the CTC I3 3D. Once I've got a usable 'stock' firmware, I can look at the upgrades I want to do, as even swapping out the extruder's filament drive mechanism would need me to reverse the extruder motor (due to the handedness of the drive assembly required to clear the mounting bracket). ''I did succeed in making a backup using AVRDUDE and a PICkit 2.''<br><br />
<br><br />
Edit: The Arduino 'bumper' is usable - a bit tight, so either my X and/or Y scaling is fractionally off or the Elegoo Mega2560 clone PCB is fractionally oversize.<br><br />
<br />
=== 17 Jan 2022 - Running my own Marlin build and finding/fixing more mechanical defects ===<br />
Progress of a sort on the CTC DiY I3 3D printer . . .<br><br />
<br><br />
The stock firmware is fairly sucky, ''probably doesn't have thermal runaway protection,'' and CTC don't appear to have released their source :( so I've been working on configuring a Marlin 1.1.9 build to run on it. Its only got an ATmega1284P ''(which has 128K Flash program memory)'', and I'm currently at 95% used, so Marlin 2.0.x isn't really a good option as I'd have to pare it down too much. Unfortunately those who have been there before me had a DiY I3 with a different controller so its been a fight to hack the config files into a usable state for it. I've still got some FUBARed Z motion defaults I need to sort put before it tries to get the Z axis to dig for Australia again! Maybe I should restore the backup of the original firmware and time some motions . . .<br><br />
<br><br />
In other news, there is supposedly no calibration table for its thermistors that's usably close, so I've had to generate one fudged from an Excel spreadsheet and some dodgy temperature measurements taken with a 1N914 diode stuffed up the hot end<br><br />
''My life was complicated here by the lack of any thermometer that could survive hot end temperatures.''<br> <br />
<br><br />
Bed Levelling needs some work, I'm trying to get manual mesh levelling up and running but it really *HATES* concave beds, as there is no option to automate moving to a safe height to clear the edge after homing off the edge of the bed. Various kludgy firmware hacks have been proposed, but I think a hardware hack is in order - use the Ymin limit switch to switch in a different height Zmin limit switch when its not over the bed, so it can be adjusted to home at a height that skims just clear of the [0,0] bed corner, then can go -Z by up to a mm or so before the regular Zmin limit trips, to allow it to level mesh points 'in the valley' without a Z probe.<br><br />
<br><br />
To that end, has anyone got a *looooooooong* lever SPDT microswitch hanging about? Flat lever and 20mm 2 hole body with terminals on the bottom preferred. Also, ideas for a cheap-skate Z probe wouldn't go amiss.<br><br />
<br><br />
''In the end I found some suitable switches on Amazon and built my dual switch Z axis limit 'Z-hop' mod. It fits in place of the original switch and if homing, with the nozzle just off the front of the bed provides a Z limit a little over 0.5mm higher than that over the bed, with the difference adjustable by bending the long switch lever. Some months later I found a BLtouch Z probe clone far cheaper than I could build any sort of deployable probe.''<br><br />
<br> <br />
Also, has anyone got experience automating acquiring temperature calibration table data for Marlin? I'm thinking maybe a Type K thermocouple bonded into a knackered brass extruder nozzle with high temperature cement, and some sort of PC interface for it, talking to Marlin with M105 SHOW_TEMP_ADC_VALUES enabled. Take it up in steps, reading the ADC and temperature for each till its good & hot, then log the cooling curve and check it matches reasonably well, and finally spit out a table in Marlin header file format.<br><br />
<br><br />
* '''CAUTION: Belt tensioners destroy themselves!'''<br />
The idiots at CTC used D shaft offcuts for the belt tensioner pully shafts and used the drive type pully for the idlers so the shaft turns with the pully. Running in a plastic hole with no bushing it acts as a D reamer and tries to chew its way back to the motor! A reasonable bodge fix is to flatten four M5 split washers ''(two for each tensioner)'', and wedge them in the recesses either side of the tensioner body, with the splits towards the tension screw. That's steel on steel, but if kept greased is better than steel D reamer on plastic! Long term it needs decent ball bearing tensioners. ''[[#18 June 2022 - Upgrading the belt tensioners with ball bearings|See below.]]<br><br />
<br />
=== 20 Jan 2022 - Flexible Z screw couplers ===<br />
The original rigid couplers between the Z stepper motors and the Z screws were unsatisfactory, as any misalignment directly pushed the gantry laterally resulting in prints with pronounced Z banding. I therefore bought some helical flexible couplers for coupling 5mm to 8mm shafts, and installed them with a 7mm ball bearing inside each to transfer the axial thrust loading from the Z screws direct to the motor shaft to minimize Z bounce. I had to shim the lead screws (which are ordinary M8 allthread) with aluminum cut from a drink can to get them concentric in the 8mm end of the coupler as their OD is slightly undersize.<br />
<br />
Although there was a notable improvement in print quality once I had carefully adjusted the coupler alignment, it wasn't a total cure as the lead screws are still shimmying enough to wobble the gentry at low Z heights. I need to decouple the drive nuts from the gantry, by flipping them the other way up and adding a thrust bearing that doesn't constrain them radially between them and the gantry. The nuts will also require anti-spin arms, and as the screws will no longer have any constraint above the couplers, they'll need top bearings.<br />
<br />
I also added a silicone 'sock' over the hotend to improve its insulation and reduce the hot touch hazard to just the nozzle itself.<br />
<br />
=== 10 Feb 2022 - Upgrades ===<br />
CTC DiY I3 3D printer progress: All slider bushings have been replaced with real linear bearings and I'm now printing a 3DBenchy in black PLA on 1.8mm glass (cut from a broken picture frame), with cooling<sup>'''*'''</sup>, using Cura 3's 'stock' slicer settings: Fine (0.1mm layers, 20% infill). So far its looking good.<br><br />
<br><br />
I need to do something about a proper enclosure for it as the ambient temperature is a bit on the low side.<br><br />
''Currently its in a cardboard enclosure made from a very large cardboard Amazon box, with a thin plastic sheet curtain front. This is a fire risk, and replacement with a non-combustible enclosure (e.g. made from plaster wallboard) or flame-retardant enclosure should be a high priority. Unfortunately running without an enclosure isn't a good option due to the number of print failures I've had due to warping caused by drafts resulting in loss of bed adhesion.''<br><br />
<br><br />
'''''<nowiki>*</nowiki> I added a 50mm centrifugal part cooling fan, stuck onto the back of the extruder motor using 3M (clone) VHB tape, with a thin aluminum tapered duct aiming at the extruder nozzle. This fan is connected to the only software controlled fan port on the Anet3D controller - FAN1. (FAN2 is permanent 12V, used for controller board cooling.) The extruder cooling fan is now wired in parallel to the hot-end heater. ToDo: design and build an extruder fan run-on circuit so sit starts when the heater is first activated, then continues to run to keep the top of the heat-break cool till the hot-end is below 100°C (or maybe simply a retriggerable timer of several minutes).''''<br><br />
<br />
=== 13 Feb 2022 - Running out of program memory! ===<br />
I just managed to build Marlin v1.1.9 with UBL (unified bed levelling) to fit in a ATmega1284P (ANET 3D v1.5 board).<br><br />
<br><br />
Will I be using it? That's a hard *NO* because to get it to fit I had to disable just about everything else except thermal protection and minimal LCD menus. No SD support, no emergency parser, no cold extrusion prevention, no endstop interrupts, no G26 mesh validation print, no M503 and a host of other minor snips and vicious GCC size optimizations. I even rewrote the Arduino LiquidCrystal library with no 8 bit support to save another hundred bytes. Also it wont fit with *any* bootloader so the only option would be to use an AVR programmer and ISP. :(<br><br />
<br><br />
''Ian B: Seems that the ANET 3D board is seriously under-spec with that processor. It wouldn't have cost them much to fit a processor with bigger ROM.''<br> <br />
''Anyway, some say UBL is all it's cracked up to be. Just get your build plate physically level, as I'm sure you have.''<br><br />
(I suspect Ian B meant: "... UBL '''isn't''' all it's cracked up to be.")<br><br />
<br><br />
''Petr Cecil: Check the bigtreetech boards on the AliExpress I had one for about 12 quids in some sale, still running on it my ender 3''<br><br />
''They got much more memory''<br><br />
<br />
=== 16 Feb 2022 - More musings on bed levelling and program memory ===<br />
I was just looking at my options before building a Z probe. I've already got manual bed levelling with a 5x5 grid installed without disabling SD support or anything else nice to have, so I've just got to look at alternatives to full UBL. e.g. switch ''(from UBL)'' to AUTO_BED_LEVELING_BILINEAR with no other changes and it goes from needing 100% + 410 bytes more (than optiboot max user progmem) to only 62%, so I should be able to turn SD support back on + most of the nice stuff I pruned. Although a more capable controller would be *nice*, this *IS* only a £99 3D printer so its hard to justify spending for a good controller before I've even got all the mechanicals up to scratch.<br><br />
<br><br />
''My 3D printer build was then on hiatus for several months. I did do a couple of non-notable successful prints on its (questionably) manually leveled bed, and spent a fair bit of time teaching myself OpenSCAD.''<br />
<br />
=== 18 June 2022 - Upgrading the belt tensioners with ball bearings ===<br />
Previously:<br />
<blockquote><br />
* '''CAUTION: Belt tensioners' destroy themselves!'''<br />
The idiots at CTC used D shaft offcuts for the belt tensioner pully shafts and used the drive type pully for the idlers so the shaft turns with the pully. Running in a plastic hole with no bushing it acts as a D reamer and tries to chew its way back to the motor! A reasonable bodge fix is to flatten four M5 split washers ''(two for each tensioner)'', and wedge them in the recesses either side of the tensioner body, with the splits towards the tension screw. That's steel on steel, but if kept greased is better than steel D reamer on plastic! Long term it needs decent ball bearing tensioners.<br><br />
<br><br />
''[[#17 Jan 2022 - Running my own Marlin build and finding/fixing more mechanical defects|Ref: 17 Jan 2022 - finding/fixing more mechanical defects]]''<br />
</blockquote><br />
[[File:CTC Tensioner.png|thumb|Belt Tensioner]]<br />
Well I finally got and fitted MR85ZZ ball bearings to both belt tensioners on my CTC DiY I3 3D printer. The bearings are ludicrously tiny, 8mm OD, 5mm ID and only 2.5mm thick, which is only 1.5mm radially for both races and the balls between them, but that's what it takes to fit the bearing recess either side of CTC's 'factory' belt tensioner. Each bearing is held in its seat by a M3 screw next to the outer race, so they aren't going anywhere. I loctited the D shaft into the front X tensioner bearing so I shouldn't have any more failed prints due to it walking out of the idler pully.<br><br />
<br><br />
For anyone else contemplating the Zuhai CTC DiY I3, I couldn't find a STL (or any other model) of the tensioner anywhere, which as supplied is a wear part, and a rapidly wearing one at that, as the D shaft will chew the holes badly out of round in only a few hours printing unless you mod it so it isn't running edged steel on plastic, so (as usual) I modelled it in OpenSCAD, taking the dimensions as accurately as I could from the 'factory' tensioner. Get the tensioner model here: [[File:Tensioner4.zip]]<br><br />
<br />
=== 25 June 2022 - Testing a BLtouch probe ===<br />
<br />
I'm (slowly) working on adding auto bed levelling to my CTC DiY I3 3D printer.<br><br />
Here's an Arduino sketch to bench test a BLtouch/3Dtouch (or clone) levelling sensor, that lets you set probe states by single letter serial commands and reports the ZMIN output status, like this:<br><br />
<br />
*** BLtouch/3Dtouch probe tester ***<br />
D = Deploy<br />
T = Tswitch<br />
R = Retract<br />
S = Self test<br />
A = Alarm off<br />
? = read ZMIN<br />
The Arduino LED echoes the ZMIN state, ON=High / OFF=Low<br />
__________________________________________________________________<br />
________________#___________________________________#_#___________<br />
____________________###______####_______##########_________####___<br />
____####__________________________________<br />
ZMIN is Low (0.10V)<br />
____________________________######################################<br />
ZMIN is High (5.00V)<br />
#################_________________________________#_______________<br />
<br><br />
The sketch: [[File:BLtouch tester.zip]]<br />
<br />
=== 29 June 2022 - Mounting the BLtouch, and building Marlin to support it ===<br />
Slight progress on adding a BLtouch (clone) ABL sensor to my Zuhai CTC DiY I3, 3D printer. I've got the probe bracket printed and the BLtouch mounted on my printhead, with only 26mm Y offset, and nearly no X offset, without blocking access to the top of the throat in case of filament problems.<br><br />
<br><br />
''I drilled two 3mm holes just in from the front edge of the L bracket that holds the print head assembly to the X gantry carriage, in front of the mounting block that holds the hotend, to fix the bracket to with 2.5mm self-tappers from underneath into the printed probe bracket. My bracket was a little too low for the optimum probe height relative to the nozzle tip (above the tip by half the probe extension), so I ended up shimming it with a piece of wooden coffee stirrer. Once I touched it in with a black marker, you wouldn't know the shim is there, so although I fixed my OpenSCAD' bracket model, I'm going to be lazy/frugal and not re-printt it'<br> <br />
<br><br />
My printer uses an ANET3D v1.5 controller, so I've only got 128K FLASH on the ATmega1284P MCU to play with (half that on the usual ATmega2560 based boards), which has made building Marlin 1.1.9 small enough to fit with AUTO_BED_LEVELING_BILINEAR and BLTOUCH enabled quite a challenge.<br><br />
Even with aggressive GCC optimizations, (see links section below) it didn't quite fit until I disabled the boot screen. It was a choice between that and ditching Optiboot. :( <br />
Sketch uses 129932 bytes (99%) of program storage space. Maximum is 130048 bytes.<br />
Its a 'full fat' Marlin v1.1.9, with full menu, SD support and all the other nice to have goodies enabled., and I've still got 116 bytes left for any tweaks I want to add! 😁 <br><br />
<br><br />
''Petr Cecil: Just keep important features like thermal runaway protection on in marlin so you don't burn your home :))''<br />
<br />
''Yes, keeping thermal runaway protection was my highest priority. Without it, you are one loose screw away from a house fire! Many thanks to Petr for letting me use his crimper and JST connector parts to make up a JST XH-3 cable I badly needed for my BLtouch install. For anyone else needing JST XH (and duPont) crimping capability, here's what Petr recommends:'' <br />
https://www.amazon.co.uk/gp/product/B07VX6YGQ8/ ''and having used it, I would also recommend it.''<br><br />
<br />
=== 1 July 2022 - Wiring the BLtouch probe ===<br />
I've got most of the recabling done on my CTC DiY I3 for the BLtouch probe. I've spliced a three wire breakout cable for +5V Gnd and servo signal into my display ribbon cable, and re-done the loom to the printhead to add the BLtouch extension cables. All that's left to do is assemble the adapter board that Petr helped me with the JST cable for, mount and wire it, flash a BLtouch enabled Marlin build, and then I'll need to calibrate the Z offset.<br><br />
<br><br />
[[File:BLtouch combiner board.png|thumb]]<br />
... and here's the circuit I intend to use to combine use of the regular limit switch which is set up to inhibit Z movement approx half a mm below the bed surface (less than the flex in the gantry) so it cant 'dig for Australia' if for any reason the BLtouch wasn't deployed before homing.<br><br />
<br><br />
''I constructed the combiner board on Veroboard, laying it out using [https://veecad.com/ VeeCAD], from the schematic I drew up in [https://www.tinycad.net/ TinyCAD], mounted it to the printer and wired it up.''<br />
<br />
=== 5 July 2022 - Visualizing the bed levelling mesh ===<br />
Meanwhile, I've been futzing around with visualising 3D printer bed levelling meshes from Pronterface *without* pasting the M420 V mesh data into a website. Marlin comes with an OpenSCAD mesh visualiser called [https://github.com/MarlinFirmware/Marlin/blob/1.1.x/buildroot/share/scripts/MarlinMesh.scad MarlinMesh.scad], and it turns out that all you need to do to get external mesh data into that is to pass it in on the OpenSCAD command line as variables defined by -D override variables with file scope defined in the file. <br />
<br />
The prerequisites for using it are explained here, but if you've already got OpenSCAD installed and are using mesh bed levelling, you'll only need to skim this: https://3dwork.io/en/visualize-3d-mesh/<br />
<br />
To do this from Pronterface, with a hard coded mesh, as I hadn't figured out the M420 mesh parsing yet, put MarlinMesh.scad in the printrun directory and (on windows) in Pronterface send:<br />
<br />
!os.system('start /max "" "C:\Program Files\OpenSCAD\openscad.exe" MarlinMesh.scad -D $vpd=800 -D measured_z= <br />
[[-0.086,-0.045,-0.037,-0.046,-0.167,-0.292,-0.421],[+0.034,+0.038,-0.002,+0.017,-0.017,-0.121,-0.413], <br />
[+0.122,+0.098,+0.162,+0.034,-0.069,-0.234,-0.472],[+0.205,+0.196,+0.120,+0.071,-0.007,-0.149,-0.467], <br />
[+0.175,+0.174,+0.102,+0.010,-0.130,-0.313,-0.587],[+0.194,+0.189,+0.116,+0.034,-0.042,-0.170,-0.568], <br />
[+0.128,+0.089,+0.032,-0.033,-0.168,-0.373,-0.594]]')<br />
<br />
Note that this is currently Windows only, as the os.system() command string to launch OpenSCAD and return immediately:<br />
'start /max "" "C:\Program Files\OpenSCAD\openscad.exe" '<br />
will be very different under LINUX or OSX. The rest of the command line should be the same.<br />
<br />
Also I would strongly recommend editing the default mesh in MarlinMesh.scad (lines 24-30) to be a minimal 'null' mesh:<br />
measured_z=[[0,0],[0,0]]; //minimal mesh<br />
to make it obvious if your mesh data hasn't been passed in successfully.<br />
<br />
ToDo: Write a script to send G420 V to the printer and parse the returned mesh data into a string containing the mesh in the above OpenScad list of lists format, that can simply be appended to the os.system() command line after the -D measured_z=<br />
<br />
''Later that evening:''<br><br />
I've written and tested the Pronterface macro to launch MarlinMesh.scad from Pronterface with the printer's current MBL mesh from a M420 V report of the form:<br />
Bilinear Leveling Grid:<br />
0 1 2 3 4 5 6<br />
0 -0.086 -0.045 -0.037 -0.046 -0.167 -0.292 -0.421<br />
1 +0.034 +0.038 -0.002 +0.017 -0.017 -0.121 -0.413<br />
2 +0.122 +0.098 +0.162 +0.034 -0.069 -0.234 -0.472<br />
3 +0.205 +0.196 +0.120 +0.071 -0.007 -0.149 -0.467<br />
4 +0.175 +0.174 +0.102 +0.010 -0.130 -0.313 -0.587<br />
5 +0.194 +0.189 +0.116 +0.034 -0.042 -0.170 -0.568<br />
6 +0.128 +0.089 +0.032 -0.033 -0.168 -0.373 -0.594<br />
echo:Bed Leveling Off<br />
echo:Fade Height Off<br />
<br />
[[File:Bed mesh.png|thumb|My poor bed looks like a map of the Himalayas!]]<br />
So I've now got a Pronterface button that visualizes my bed live, without resorting to an online bed visualizer WWW site. 😁<br />
<br />
''Even with ABL enabled, its useful to let you see if your whole bed is out of whack' and could benefit from adjusting its levelling screws to reduce the range of Z offsets the ABL has to compensate for.'' <br />
<br />
It is currently Win x64 only, as the command line to launch OpenSCAD is OS specific. It shouldn't be hard to change that for Linux or OSX.<br />
<br />
To add it to your own Pronterface, first put MarlinMesh.scad in your Printrun folder, then paste the following into a new Pronterface macro:<br />
<pre><br />
!################# Bed Visulization macro #################<br />
!# Pronterface script to invoke OpenSCAD MarlinMesh with #<br />
!# the current MBL mesh returned by M420 V. #<br />
!# #<br />
!# (c) Ian.M 7/7/2022 #<br />
!# #<br />
!# "THE BEER-WARE LICENSE" (Revision 42): #<br />
!# "Ian.M" <https://t.me/Ian_M_2019> wrote this stuff. #<br />
!# As long as you retain this notice you can do whatever #<br />
!# you want with this stuff. If we meet some day, and #<br />
!# you think this stuff is worth it, you can buy me a #<br />
!# beer in return. Ian.M #<br />
!##########################################################<br />
!<br />
!import time<br />
!import os<br />
M420 V ; requst ML grid<br />
!time.sleep(1) # wait for it<br />
!idx=len(self.p.log)-1 # get last line in log buffer<br />
!idxf=None # error value <br />
!idxl=None<br />
!for x in range(idx,max(idx-20,0),-1): # iterate backwards <br />
! if self.p.log[x].find("Grid:")>8: # looking for 'Grid:', if found:<br />
! idxf=x+2 # set idxf to first (real) line of grid <br />
! break; # and exit loop<br />
! if self.p.log[x].find("echo:")==0: # looking for 'echo:', if found:<br />
! idxl=x-1 # set idxl to previous line till last line of grid is found<br />
!<br />
!#print("Debug: range "+str(idxf)+", "+str(idxl))<br />
!<br />
!if (idxf is None) or (idxl is None): # M420 failed<br />
! self.logError("Error: M420 failed")<br />
! return<br />
!if idxf>idxl: # M420 no grid<br />
! self.logError("Error: M420 did not return a grid")<br />
! return<br />
!<br />
!mesh="["<br />
!for x in range(idxf,idxl+1): # build list of OpenScad lists<br />
! mesh=mesh+"["+str(self.p.log[x])[3:].rstrip().replace(" ",",")+"]" # build comma separated list<br />
! if x<idxl:<br />
! mesh=mesh+"," # more to follow<br />
! else:<br />
! mesh=mesh+"]" # last one - end outer list<br />
!<br />
!# Build MMcmd for OpenSCAD installed in default location on 64 bit Windows.<br />
!# N.B use explicit 64 bit Program Files directory as Pronterface is a 32 bit application,<br />
!# so %ProgramFiles% returns %ProgramFiles(x86)%, which is the wrong folder.<br />
!MMcmd='start /max "" "%ProgramW6432%\\OpenSCAD\\OpenSCAD.exe" ' # change this OS dependent stuff!<br />
!MMparams="MarlinMesh.scad -D $vpd=800 -D measured_z=" # OpenSCAD command line parameters<br />
!# n.b. MarlinMesh.scad must be in printrun working directory<br />
!# -D defines an OpenSCAD constant for the session, overriding variables within the file. <br />
!<br />
!print("Invoking MarlinMesh.scad with this mesh.")<br />
!print("Exec: "+MMcmd+MMparams+mesh)<br />
!os.system(MMcmd+MMparams+mesh) #Execute it<br />
</pre><br />
<br />
''Edit: It turns out, that depending on your Pronterface version, you'll probably need to import '''os''' and '''time''' at the top of the macro. I've added them above.''<br />
<br />
=== 10 Sept 2022 - Z-screw wobble isolation ===<br />
Back in January I wrote:<br />
<blockquote><br />
The original rigid couplers between the Z stepper motors and the Z screws were unsatisfactory, as any misalignment directly pushed the gantry laterally resulting in prints with pronounced Z banding. I therefore bought some helical flexible couplers for coupling 5mm to 8mm shafts, and installed them with a 7mm ball bearing inside each to transfer the axial thrust loading from the Z screws direct to the motor shaft to minimize Z bounce. I had to shim the lead screws (which are ordinary M8 allthread) with aluminum cut from a drink can to get them concentric in the 8mm end of the coupler as their OD is slightly undersize.<br />
<br />
Although there was a notable improvement in print quality once I had carefully adjusted the coupler alignment, it wasn't a total cure as the lead screws are still shimmying enough to wobble the gentry at low Z heights. I need to decouple the drive nuts from the gantry, by flipping them the other way up and adding a thrust bearing that doesn't constrain them radially between them and the gantry. The nuts will also require anti-spin arms, and as the screws will no longer have any constraint above the couplers, they'll need top bearings.<br />
</blockquote><br />
<br />
At long last, I've completed the next stage of this, by laser cutting new top brackets and bearing retainers for 688ZZ ball bearings (8mm ID, 16mm OD, 5mm wide) from plywood, consisting of a redesigned bracket in 5mm ply, with a 16mm hole for the bearing which fits flush, surrounded by six tiny holes to fix retaining rings cut from 3mm ply above and below the bracket, each held by three tiny 2mm screws. I also laser cut the anti-spin arms for the Z-nuts from 5mm black Acrylic. All ply parts were spay painted matte black to match the rest of the printer frame. A Thursday evening well spent.<br />
<br />
I installed the parts and after some fiddling around managed to reduce the Z-screw runout, and got the screw centered well enough in the gantry end nut mounts not to touch and jerk. I still haven't got proper thrust bearings, and am making do with a stack of three M10 washers on the long end of each Z-nut, which have *NOT* been flipped as originally planned, as it looks like I'll need something other than the Z-screw to loosely constrain the thrust bearing. The washers are lightly greased so can slide over each other fairly readily<br />
<br />
After re-leveling (and some BLtouch calibration issues that were borking my first layer height), I finally managed to print a good test cube. Its got much less pronounced Z banding than before this upgrade. Hopefully adding ball thrust bearings will eliminate most of the residual banding. ToDo: design & fabricate cages for these bearings. The problem is a lack of space - I haven't got a lot of height between the top of the coupler and the bottom of the nut, and also, anything much larger than the 22mm OD of the nut flange would force me to move the part cooling fan and redesign its duct.<br />
<br />
''OpenSCAD design files and photos to follow''<br />
<br />
=== 06 January 2023 ===<br />
Another hiatus - I didn't need to do any 3D printing and was busy learning the RML mini-lathe.<br />
However I've made a small but significant improvement to the Z axis with nothing more than a few square cm of waxed paper! I took the backing paper off some double-sided tape, and wrapped one turn of the paper round the Z screw to make a spacer to fit inside the stack of washers. It sits over the lip on the end of the nut, inside the ID of the washer stack and helps the washer stack stay centered on the screw so none of them touch the screw, catch and jerk, but is so flimsy that the washers can still slide laterally with minimal extra force on the X gantry. A test cube showed much reduced Z banding vs the previous one from October.<br />
<br />
Its still not good enough as there is far too much runout at the bottom of the right-hand lead-screw which is shifting the X gantry support force to and fro enough to wobble it. Either I've got a bad coupler, its poorly assembled or there is a kink in the end of the screw where it was cut. Probably the best option will be to chuck the leadscrew in a soft collet in the lathe, get it running true, then turn the thread off the end of the leadscrew, shrink on a short bored out piece of steel rod, then turn that to 8.00 mm diameter, concentric to the screw, so I'm no longer trying to clamp on the threaded end.<br />
<br />
=== 13 December 2023 - Better Leadscrew Concentricity ===<br />
Some 3D printing of small parts this year, and several false starts with improving the lead screws. I spent quite a bit of lathe time doing test pieces with short lengths of M8 allthread. <br />
<br />
The soft collet idea was a non-starter as anything that grips on the thread tips gives poor concentricity. It turns out the answer is to wind a helix of soft iron or mild steel wire that fits the thread and grip on that so the grip is on the flanks of the thread. Also, shrink fitting was a bust - the precision and surface finish required to make it work for such small parts is right at the limit of RML's capabilities, and the tiny thermal mass gives only seconds to fit it and a fraction of a second to slide it home. The answer was loctite + machining to a push fit. 11 mm long, ~5.6 mm bore steel sleeves were made from 3/8" (9.5 mm) stock, and the thread turned down to fit for ~11 mm from the screw end. We don't have good enough bore measuring capability at RML so a test plug was turned to fit drilled bore to get the diameter to work to. Loctite was applied to both surfaces and the sleeve tapped on firmly. The OD was then turned to 8.00 mm and faced to 10 mm length, just cleaning up the screw end to get a true uniform end face, and the edge chamfered. <br />
<br />
I've got one leadscrew done, but time and machining mistakes were against me (I screwed up the 8.00 mm OD and had to turn the sleeve off and re-do it) so didn't get the second screw done. That's a job for tomorrow. <br />
<br />
Fitting and removing the screws now requires top corner plate removal. Run the gantry right up and hang it from the frame, then run the Z-nuts and their anti-rotation arms back down. Undo the coupler and take off the corner plate. The guide rod can be lifted and the anti-rotation arm swung clear, then the bottom end of the screw can be lifted off and slid down and forward till it can be slid out of the gantry end. Refitting is the reverse of removal.<br />
<br />
I've already got the left Z screw fitted, and the result is no obvious runout. Its highly dependent on the tightening sequence of the lower part of the helical coupler as excessive pressure with the split clamp causes the D shaft to go off center, so that should be lightly snugged up then the grubscrew tightened firmly on the flat. The grubscrew must be well aligned with the flat. Turn the other Z motor shaft to turn the one being assembled for access to the screws, as the coupler initially wont be tight enough to turn the motor.<br />
<br />
=== 15 December 2023 ===<br />
I machined the other screw yesterday evening and fitted it this morning, again with no obvious runout. I did some manual levelling to get the bed as near true to the Y rails as possible and the X gantry true to the frame and hopefully to the bed, then started automatic bed levelling, stored the resulting map, and started printing an XYZ calibration cube.<br />
<br />
== - more to follow - ==<br />
<br />
== Some useful links ==<br />
* https://github.com/ralf-e/ANET-3D-Board-V1.0 - Schematic for an earlier version of the controller, near enough the same as the v1.5, and for the LCD2004 display/buttons board. Note that connector pinouts should be checked against the actual board before trusting them. e.g. I know the end stop connectors have pins 1 and 3 swapped vs the schematic.<br />
<br />
* http://lokspace.eu/anet-a8-wifi-mod/ - How to add printing over WiFi using an ESP-01 ESP8266 WiFi module and esp-link, by populating the Anet3D 'USB BLE' header + removing two zero ohm resistors. Level shifting is needed to get the 5V level ATmega TX pin down to 3.3V levels for the ESP8266 RX pin, hence the resistors on the carrier board. There's also no need for a USB UART adapter to flash the ESP8266, as the ANET main board has one of those. After dong the mainboard mod, simply take two short duPont F-F jumpers and link opposite corner pins of J8 the 'USB BLE' header, and use the mainboard's USB port. After flashing, remove the duPont wires, fit two jumper caps in the BLE position, and carry on with esp-link setup. Alternatively, use a Wemos D1 Mini clone which has all you need on-board except the level shifter, and its simple enough to solder two resistors for that. See my page [[WiFi 'tethered' Arduino robot]]<br />
<br />
* https://docs.arduino.cc/software/ide-v1/tutorials/PortableIDE - how to set up a portable install of the classic Arduino IDE which is strongly recommended for any existing Arduino user for building Marlin 1.1.x as you are likely to need to down-version the core and various libraries.<br />
<br />
* https://spiritdude.wordpress.com/2018/03/26/ctc-diy-prusa-i3-ctc-diy-i3-pro-b-most-affordable-3d-printer-2018/ - Another user's experiences with this printer.<br />
<br />
* https://ufj.ddns.net/blog/marlin/2019/01/07/reducing-marlin-binary-size.html - Turning on aggressive AVR GCC optimizations to reduce the size of the Marlin firmware, so it will fit in 128K program memory without having to prune too many desirable features.<br />
<br />
* https://all3dp.com/2/epic-3d-printing-fails-and-why-they-failed/ - some of the many ways things can go badly, ranging from potentially life-threatening, down through expensive and tedious, to mildly amusing.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_%C2%A399_ZHUHAI_CTC_DiY_I3_3D_printer&diff=17597Ian M's £99 ZHUHAI CTC DiY I3 3D printer2023-12-15T09:49:50Z<p>IanM: /* 13 December 2023 - Better Leadscrew Concentricity */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br><br />
<br />
The ZHUHAI CTC DiY I3 Pro B 'Prusa' clone printer is rather similar to RML's [[Geetech I3 Pro B]] except with a laser cut plywood frame instead of acrylic, and cheapened in many key areas, which I'm working on upgrading. Its my personal 3D printer and is not kept at RML.<br />
[[File:Ian's CTC I3 After BLtouch upgrade.jpg|thumb]]<br />
== The DiY kit and the build ==<br />
Here's CTC's official build video: https://youtu.be/PSzcU48wczk<br />
=== Differences on my printer ===<br />
* IEC power inlet (Video has direct attached mains lead)<br />
* Bed levelling screws have countersunk heads so there are no obstructions at the bed corners<br />
<br />
=== Hints & Tips that didn't make it into the build log ===<br />
* Buy a pack of M3 washers and insert one in each T-slot in the frame, between the nut and the wood it bears on, to spread the pressure and prevent the nut chewing the wood.<br />
<br />
* A pair of M8 nuts can be used to 'hang' the lead screws and gantry assembly from the top of the frame while working on the steppers or shaft couplers.<br />
* Put a *VERY* large cable tie right round the body of the extruder and X steppers, with the tail coming straight up at the back of the extruder, and straight down off the X stepper, then cable tie the wiring to the big tail to anchor it before you spiral wrap, Leave the big tail full length inside the spiral wrap to stiffen the loom near the motor. A similar large cable tie round the lower right board fan standoff, snug but not tight so it can pivot on the standoff, can be used to anchor the lower end of the X loom.<br />
<br />
* The 2004 control/display PCB is probably being warped by its plywood frame and the absence of spacers between the board and the back not allowing for the solder joints with slightly protruding header pins. Dismantle it and shim for clearance behind the board with nuts/washers/etc. taking care not to short anything. You may need to file out the bolt holes in the ply so the board fits properly without being forced into a curve before reassembling and mounting it.<br />
<br />
== Build log from my posts on the RML Telegram group ==<br />
''Currently, a mostly verbatim copy of my 3D printer related posts, with some corrections and additions to my posts + some responses to my posts from other members. If you feel I've misrepresented what you said, or you don't want to be quoted, and you don't have edit rights here, PM me on Telegram!''<br><br />
<br><br />
''ToDo: Transfer more stuff from Telegram here and edit it into a coherent project writeup.''<br />
<br />
=== 6 Jan 2022 - Arrival and initial mechanical assembly ===<br />
A cheap (£99) Prusa i3 clone 3D printer kit should be landing on my doorstep later on this afternoon . . .<br><br><br />
{<s>photo from manual</s>, ''not posted here due to copyright''}<br><br><br />
It arrived.<br><br />
Its actually a ZUHAI CTC DiY I3 PRINTER with a wooden frame, and an ANET A8 v1.5 clone controller board. That’s more or less what I expected as a *real* Prusa for under a ton just isn't happening unless its a BER parts mule. Next: dig through the documentation, such as it is . . .<br><br />
<br><br />
''Mike: “Hi Ian, is it £99?”''<br><br />
<br><br />
Yep. It was £99 from Amazon. https://www.amazon.co.uk/gp/product/B015GDDXJA<br />
<br>I've done the full mechanical assembly, and knocked off for the night *WITHOUT* starting any wiring.<br><br />
<br><br />
For anyone else contemplating this one, beware: the rails are steel tube, not rod, it has plastic slider bushings not linear bearings, and the Z drive nuts are aluminum, not bronze or brass. Also the filament drive is not adjustable for pressure, and there are very few free GPIOs on the controller available for custom stuff. (There's the three SPI pins of the ISP port J3 ''if you disable SD card support'', one pin on the LCD connector reserved for a beeper on some display boards, and I suppose you could free up two more analog capable pins and UART1 TX & RX if you added an I2C LCD driver board.)<br><br />
<br>[[File:Ian's CTC I3 IEC Boot + extra clamping nuts on Y strut.jpg|thumb]]<br />
* '''CAUTION: THERE ARE EXPOSED MAINS TERMINALS'''<br><br />
As soon as I've got it dialled in I need to print a cover for the back of the IEC connector, and do something better than the flip-up cover over the PSU mains terminals. ''I ended up putting a rubber boot made from bicycle inner tube over the back of the IEC connector secured with cable ties as it was just too unsafe adjusting the right rear bed levelling screw without insulation there.'' <br><br />
<br><br />
I've already improved the rigidity considerably by adding four M8 nuts and washers to clamp the vertical frame to the M8 allthread that joins the front and back end plates. If you do the same, you *MUST* align the frame and endplates on a dead flat surface<sup>'''*'''</sup>, and as you tighten the new nuts, use a straightedge to check you aren't bowing the vertical frame's lower cross-member. Check you get the front on again dead square. While you are in there, put a nut in the hex hole in the Y axis belt tensioner so the bolt stays put while you adjust the wing nut.<br><br />
<br><br />
I'm sure I'll be buying other bits for it, once its up and running. e.g. flexible couplings + bearing balls for thrust for the Z screws to reduce shimmy, cheap but real linear bearings, and an all metal adjustable pressure filament drive upgrade kit.<br><br />
<br><br />
'''''<nowiki>*</nowiki> The flatness of the assembly surface is crucial - 0.2 mm lift of one side of the front plate relative to the rest of the frame, becomes 0.1 mm of varying bed tilt as the bed moves from min. Y to max. Y or visa-versa, giving the illusion the bed surface is saddle shaped, but also resulting in increasing lateral distortion the greater the print height is above the bed rails. Once assembled flat and true, it *should* be operated on an equally flat surface to maintain alignment, but if your table is of questionable flatness, the printer can be shimmed under its frame, and front and back plates to maintain six points of contact, and its position on the table marked to remind you to keep it in the position you've shimmed flat for it.''''<br><br />
<br><br />
<br />
=== 9 Jan 2022 - Wiring and problems ===<br />
Doing the CTC I3 3D printer wiring neatly took most of Saturday afternoon. Then it didn't work! 😢<br><br />
''Back in January, the extra board above the main board (to combine the normal Z limit switch and the BLtouch probe output), and all wiring to it was not present, and only the standard single short-lever Z limit microswitch was fitted.''<br />
[[File:Ian's CTC I3 Boards and Wiring.jpg|thumb|The main board and wiring]]<br />
<br><br />
Diagnosing its ills took the whole evening - one of the Z steppers had a broken wire. After carefully teasing the offending pin out of the stepper cable connector, I cleaned out the old crimp and soldered it and both steppers stepped uncoupled. It helps to use a couple of M8 nuts, put on the tops of the Z screws to hold them up so the X axis doesn't have to be dismantled when working on the Z steppers and couplings. The left side was binding and the right side wasn't a whole lot better. Turns out the laser cut bracket motor mounts don't line up with the screw when the Z axis is near the bottom. It’s fiddly but it is possible to remove the motors without extra dismantling. Some careful filing to elongate the mounting holes to line up the motor and final tightening after the coupling was slid over the screw end, and it no longer binds.<br> <br />
<br><br />
However, it still failed to home. 😾 Investigating the limit switch signals found the odd one out was the Y axis which read as homed when it wasn't. The switches are all NC microswitches, and I was getting ready to replace it, when I found its connections failed the tug test on both wires! The wires were broken under enough OEM heatshrink to confuse the issue. Resoldering them and applying new heatshrink fixed that and it now homes.<br><br />
<br><br />
I suspect the motor wire was a bad crimp, and the switch wires most likely broke because they were 'flapping in the breeze' while the bed, Y axis and lower frame assembly was being packed and shipped.<br><br />
<br><br />
Finally I was able to test the full range of motion of all axes, do a quick & dirty manual bed levelling and set the Y zero limit screw as low as seems reasonable. (I had it high to avoid crashing the nozzle earlier.) Selecting PLA warmup showed both the heated bed and the hot-end were working, and stabilized at their setpoints, though I'm getting an initial 10 deg C overshoot during hot end warmup, so it probably needs some tuning.<br><br />
<br><br />
I then tried to load and feed filament - no joy - it didn't want to feed, and when I manually encouraged it all I got for my trouble was a clogged hot-end. Taking the extruder off, dismantling it and careful reassembly of the feeder got it feeding, but I still had the clog to deal with.<br> <br />
<br><br />
I suspected the PTFE tube liner in the heat-break wasn't seating properly, which is what probably caused both the feed problem and the clog. I dismantled the hot-end and extracted the PTFE tube - clogged solid and fatter than the throat at the top of the heat-break tube. I managed to press the clog out with the stem of an Allen key, then close inspection of the PTFE tube found neither end was square. I shaved the better end square, and chamfered the entry to the other end by twiddling a sharp drill bit to stop the filament catching on its edge. Clearing the nozzle was a PITA, eventually it succumbed to a cold pull done off the hot end, supporting the nozzle with a small ring spanner and heating it with a lighter.<br><br />
<br><br />
I then bench tested the extruder, and it now feeds and extrudes, (manually using the axis menu). Its really fiddly to bolt back on to the X carriage without stripping it to separate the bracket, but after a lot of faffing about and some rather unparliamentary language I got it back on properly, leaving it loaded with filament from the bench test.<br><br />
<br><br />
Finally I checked it still homes and that the bed levelling hadn't gone too far out while I was working on it, and shut it down for the night.<br><br />
<br><br />
ToDo: Try printing something!<br><br />
<br><br />
<br />
=== 9 Jan 2022 - Q&A with Ian B, dangerous mains plug, and sellers 'bait & switch'! ===<br />
''Ian B: “Ian, that's quite a log of problems solved. It certainly shows a lack of QC from the manufacturer.''<br><br />
<br><br />
''It seems you've approached each fault methodically. (I would expect nothing less from you.) Heating the extruder with a lighter is something I've never heard of before, useful technique.''<br> <br />
<br><br />
''I wish you luck with the first print. Keep it small and simple.''<br><br />
<br><br />
''Then I wish you ongoing luck with all subsequent prints, too.”''<br><br />
<br><br />
If you try my lighter trick, to avoid bouncing a hot-ish nozzle round the room, it would probably be a better idea to screw the nozzle into a M6 nut, and hold it in mole grips with card for thermal isolation from the grips, and clamp the grip handles flat in a vice. The nut will also increase the thermal mass making the whole process more controllable.<br><br />
<br><br />
I forgot to mention the illegal ('The Plugs and Sockets etc. (Safety) Regulations 1994' - UK Statutory Instruments 1994 No. 1768) undersized and unfused mains plug on its supplied IEC lead. Its pins were so far undersize that there was no retention force in a standard socket!<br><br />
<br><br />
John Ward on these counterfeit leads & plugs: https://www.youtube.com/watch?v=9KMrWupFQt4<br />
<br><br />
AITA if I try to nail Amazon's balls to the wall for "not as described" and the illegal mains lead? It was still a reasonably good deal as supplied . . .<br><br />
<br><br />
==== Description from Amazon product page at time of sale ====<br />
* Brand Josef Prusa<br />
* Material Carbon Fibre<br />
<br />
'''Product description - Technical specifications'''<br />
* Print area - 8x8x8 inches (20x20x20 cm)<br />
* Open frame design for easy use<br />
* Integrated LCD for use without a computer<br />
* SD card support (8GB included) and USB port<br />
* Geniune E3D 1.75mm hotend and RAMBo mini motherboard<br />
* Easy multicolor printing feature based on layer height<br />
* Layer height from 50 microns<br />
* Heated print bed for warpless printing from any material<br />
* Supported materials - PLA, ABS, PET, HIPS, Flex PP, Ninjaflex, Laywood, Laybrick, Nylon, Bamboofill, Bronzefill, ASA, T-Glase, Carbon-fiber enhanced filaments...<br />
* Step size in X/Y axes - 10 micron<br />
* 2 lbs (1 kg) Silver PLA included<br />
<br />
==== DISCREPENCIES (so far) ====<br />
* Not a genuine Josef Prusa printer - its a ZHUHAI CTC ELECTRONIC CO. model.<br />
* Plywood frame, and no carbon fibre components<br />
* Less than 20cm X travel - measured 18.6cm from mechanical limit to limit<br />
* No SD card supplied<br />
* Not a "Geniune (sic) E3D 1.75mm hotend" - its got a bargain basement generic clone hotend<br />
* Not a "RAMBo mini motherboard" - its got an Anet A8 v1.5 clone, with a lesser MCU, no max. endstop switch inputs, one less thermistor input, and only three PWMed MOSFETs, so only one controlled fan can be connected.<br />
* No "2 lbs (1 kg) Silver PLA included" - Three sample coils of approx 12m each, total under 120g supplied<br />
<br />
=== 12 Jan 2022 - First Print and another defect found ===<br />
The CTC I3 3D printer prints!<br><br />
<br><br />
I'm currently using Cura 3.2.1, and so far have done a test cube and am currently trying an Arduino Mega2560 'bumper' generated from an OpenSCAD library. I aborted the first run after a couple of layers to have something to check against the Arduino board - it looks reasonable, so I'm doing a proper run, and hoping it comes out well enough to use. <br><br />
<br><br />
More defects found! The X tensioner bolt has a really crappy rolled thread and wont hold in the wing-nut. An ordinary M3 nut on it has just enough grip to be usable. I need to replace it with a long M3 machine screw, so I can get a nut into the tensioner body to hold it, so it doesn't spin when I adjust the wing nut. ''Subsequently fixed with a length of M3 stainless allthread, with the end mushroomed slightly and a hex nut Loctited on flush to effectively make that long machine screw.''<br><br />
<br><br />
Next job will be to see if I can backup the existing firmware then look at what it takes to get Marlin built for an Anet A8 v1.5 controller, and configured for the CTC I3 3D. Once I've got a usable 'stock' firmware, I can look at the upgrades I want to do, as even swapping out the extruder's filament drive mechanism would need me to reverse the extruder motor (due to the handedness of the drive assembly required to clear the mounting bracket). ''I did succeed in making a backup using AVRDUDE and a PICkit 2.''<br><br />
<br><br />
Edit: The Arduino 'bumper' is usable - a bit tight, so either my X and/or Y scaling is fractionally off or the Elegoo Mega2560 clone PCB is fractionally oversize.<br><br />
<br />
=== 17 Jan 2022 - Running my own Marlin build and finding/fixing more mechanical defects ===<br />
Progress of a sort on the CTC DiY I3 3D printer . . .<br><br />
<br><br />
The stock firmware is fairly sucky, ''probably doesn't have thermal runaway protection,'' and CTC don't appear to have released their source :( so I've been working on configuring a Marlin 1.1.9 build to run on it. Its only got an ATmega1284P ''(which has 128K Flash program memory)'', and I'm currently at 95% used, so Marlin 2.0.x isn't really a good option as I'd have to pare it down too much. Unfortunately those who have been there before me had a DiY I3 with a different controller so its been a fight to hack the config files into a usable state for it. I've still got some FUBARed Z motion defaults I need to sort put before it tries to get the Z axis to dig for Australia again! Maybe I should restore the backup of the original firmware and time some motions . . .<br><br />
<br><br />
In other news, there is supposedly no calibration table for its thermistors that's usably close, so I've had to generate one fudged from an Excel spreadsheet and some dodgy temperature measurements taken with a 1N914 diode stuffed up the hot end<br><br />
''My life was complicated here by the lack of any thermometer that could survive hot end temperatures.''<br> <br />
<br><br />
Bed Levelling needs some work, I'm trying to get manual mesh levelling up and running but it really *HATES* concave beds, as there is no option to automate moving to a safe height to clear the edge after homing off the edge of the bed. Various kludgy firmware hacks have been proposed, but I think a hardware hack is in order - use the Ymin limit switch to switch in a different height Zmin limit switch when its not over the bed, so it can be adjusted to home at a height that skims just clear of the [0,0] bed corner, then can go -Z by up to a mm or so before the regular Zmin limit trips, to allow it to level mesh points 'in the valley' without a Z probe.<br><br />
<br><br />
To that end, has anyone got a *looooooooong* lever SPDT microswitch hanging about? Flat lever and 20mm 2 hole body with terminals on the bottom preferred. Also, ideas for a cheap-skate Z probe wouldn't go amiss.<br><br />
<br><br />
''In the end I found some suitable switches on Amazon and built my dual switch Z axis limit 'Z-hop' mod. It fits in place of the original switch and if homing, with the nozzle just off the front of the bed provides a Z limit a little over 0.5mm higher than that over the bed, with the difference adjustable by bending the long switch lever. Some months later I found a BLtouch Z probe clone far cheaper than I could build any sort of deployable probe.''<br><br />
<br> <br />
Also, has anyone got experience automating acquiring temperature calibration table data for Marlin? I'm thinking maybe a Type K thermocouple bonded into a knackered brass extruder nozzle with high temperature cement, and some sort of PC interface for it, talking to Marlin with M105 SHOW_TEMP_ADC_VALUES enabled. Take it up in steps, reading the ADC and temperature for each till its good & hot, then log the cooling curve and check it matches reasonably well, and finally spit out a table in Marlin header file format.<br><br />
<br><br />
* '''CAUTION: Belt tensioners destroy themselves!'''<br />
The idiots at CTC used D shaft offcuts for the belt tensioner pully shafts and used the drive type pully for the idlers so the shaft turns with the pully. Running in a plastic hole with no bushing it acts as a D reamer and tries to chew its way back to the motor! A reasonable bodge fix is to flatten four M5 split washers ''(two for each tensioner)'', and wedge them in the recesses either side of the tensioner body, with the splits towards the tension screw. That's steel on steel, but if kept greased is better than steel D reamer on plastic! Long term it needs decent ball bearing tensioners. ''[[#18 June 2022 - Upgrading the belt tensioners with ball bearings|See below.]]<br><br />
<br />
=== 20 Jan 2022 - Flexible Z screw couplers ===<br />
The original rigid couplers between the Z stepper motors and the Z screws were unsatisfactory, as any misalignment directly pushed the gantry laterally resulting in prints with pronounced Z banding. I therefore bought some helical flexible couplers for coupling 5mm to 8mm shafts, and installed them with a 7mm ball bearing inside each to transfer the axial thrust loading from the Z screws direct to the motor shaft to minimize Z bounce. I had to shim the lead screws (which are ordinary M8 allthread) with aluminum cut from a drink can to get them concentric in the 8mm end of the coupler as their OD is slightly undersize.<br />
<br />
Although there was a notable improvement in print quality once I had carefully adjusted the coupler alignment, it wasn't a total cure as the lead screws are still shimmying enough to wobble the gentry at low Z heights. I need to decouple the drive nuts from the gantry, by flipping them the other way up and adding a thrust bearing that doesn't constrain them radially between them and the gantry. The nuts will also require anti-spin arms, and as the screws will no longer have any constraint above the couplers, they'll need top bearings.<br />
<br />
I also added a silicone 'sock' over the hotend to improve its insulation and reduce the hot touch hazard to just the nozzle itself.<br />
<br />
=== 10 Feb 2022 - Upgrades ===<br />
CTC DiY I3 3D printer progress: All slider bushings have been replaced with real linear bearings and I'm now printing a 3DBenchy in black PLA on 1.8mm glass (cut from a broken picture frame), with cooling<sup>'''*'''</sup>, using Cura 3's 'stock' slicer settings: Fine (0.1mm layers, 20% infill). So far its looking good.<br><br />
<br><br />
I need to do something about a proper enclosure for it as the ambient temperature is a bit on the low side.<br><br />
''Currently its in a cardboard enclosure made from a very large cardboard Amazon box, with a thin plastic sheet curtain front. This is a fire risk, and replacement with a non-combustible enclosure (e.g. made from plaster wallboard) or flame-retardant enclosure should be a high priority. Unfortunately running without an enclosure isn't a good option due to the number of print failures I've had due to warping caused by drafts resulting in loss of bed adhesion.''<br><br />
<br><br />
'''''<nowiki>*</nowiki> I added a 50mm centrifugal part cooling fan, stuck onto the back of the extruder motor using 3M (clone) VHB tape, with a thin aluminum tapered duct aiming at the extruder nozzle. This fan is connected to the only software controlled fan port on the Anet3D controller - FAN1. (FAN2 is permanent 12V, used for controller board cooling.) The extruder cooling fan is now wired in parallel to the hot-end heater. ToDo: design and build an extruder fan run-on circuit so sit starts when the heater is first activated, then continues to run to keep the top of the heat-break cool till the hot-end is below 100°C (or maybe simply a retriggerable timer of several minutes).''''<br><br />
<br />
=== 13 Feb 2022 - Running out of program memory! ===<br />
I just managed to build Marlin v1.1.9 with UBL (unified bed levelling) to fit in a ATmega1284P (ANET 3D v1.5 board).<br><br />
<br><br />
Will I be using it? That's a hard *NO* because to get it to fit I had to disable just about everything else except thermal protection and minimal LCD menus. No SD support, no emergency parser, no cold extrusion prevention, no endstop interrupts, no G26 mesh validation print, no M503 and a host of other minor snips and vicious GCC size optimizations. I even rewrote the Arduino LiquidCrystal library with no 8 bit support to save another hundred bytes. Also it wont fit with *any* bootloader so the only option would be to use an AVR programmer and ISP. :(<br><br />
<br><br />
''Ian B: Seems that the ANET 3D board is seriously under-spec with that processor. It wouldn't have cost them much to fit a processor with bigger ROM.''<br> <br />
''Anyway, some say UBL is all it's cracked up to be. Just get your build plate physically level, as I'm sure you have.''<br><br />
(I suspect Ian B meant: "... UBL '''isn't''' all it's cracked up to be.")<br><br />
<br><br />
''Petr Cecil: Check the bigtreetech boards on the AliExpress I had one for about 12 quids in some sale, still running on it my ender 3''<br><br />
''They got much more memory''<br><br />
<br />
=== 16 Feb 2022 - More musings on bed levelling and program memory ===<br />
I was just looking at my options before building a Z probe. I've already got manual bed levelling with a 5x5 grid installed without disabling SD support or anything else nice to have, so I've just got to look at alternatives to full UBL. e.g. switch ''(from UBL)'' to AUTO_BED_LEVELING_BILINEAR with no other changes and it goes from needing 100% + 410 bytes more (than optiboot max user progmem) to only 62%, so I should be able to turn SD support back on + most of the nice stuff I pruned. Although a more capable controller would be *nice*, this *IS* only a £99 3D printer so its hard to justify spending for a good controller before I've even got all the mechanicals up to scratch.<br><br />
<br><br />
''My 3D printer build was then on hiatus for several months. I did do a couple of non-notable successful prints on its (questionably) manually leveled bed, and spent a fair bit of time teaching myself OpenSCAD.''<br />
<br />
=== 18 June 2022 - Upgrading the belt tensioners with ball bearings ===<br />
Previously:<br />
<blockquote><br />
* '''CAUTION: Belt tensioners' destroy themselves!'''<br />
The idiots at CTC used D shaft offcuts for the belt tensioner pully shafts and used the drive type pully for the idlers so the shaft turns with the pully. Running in a plastic hole with no bushing it acts as a D reamer and tries to chew its way back to the motor! A reasonable bodge fix is to flatten four M5 split washers ''(two for each tensioner)'', and wedge them in the recesses either side of the tensioner body, with the splits towards the tension screw. That's steel on steel, but if kept greased is better than steel D reamer on plastic! Long term it needs decent ball bearing tensioners.<br><br />
<br><br />
''[[#17 Jan 2022 - Running my own Marlin build and finding/fixing more mechanical defects|Ref: 17 Jan 2022 - finding/fixing more mechanical defects]]''<br />
</blockquote><br />
[[File:CTC Tensioner.png|thumb|Belt Tensioner]]<br />
Well I finally got and fitted MR85ZZ ball bearings to both belt tensioners on my CTC DiY I3 3D printer. The bearings are ludicrously tiny, 8mm OD, 5mm ID and only 2.5mm thick, which is only 1.5mm radially for both races and the balls between them, but that's what it takes to fit the bearing recess either side of CTC's 'factory' belt tensioner. Each bearing is held in its seat by a M3 screw next to the outer race, so they aren't going anywhere. I loctited the D shaft into the front X tensioner bearing so I shouldn't have any more failed prints due to it walking out of the idler pully.<br><br />
<br><br />
For anyone else contemplating the Zuhai CTC DiY I3, I couldn't find a STL (or any other model) of the tensioner anywhere, which as supplied is a wear part, and a rapidly wearing one at that, as the D shaft will chew the holes badly out of round in only a few hours printing unless you mod it so it isn't running edged steel on plastic, so (as usual) I modelled it in OpenSCAD, taking the dimensions as accurately as I could from the 'factory' tensioner. Get the tensioner model here: [[File:Tensioner4.zip]]<br><br />
<br />
=== 25 June 2022 - Testing a BLtouch probe ===<br />
<br />
I'm (slowly) working on adding auto bed levelling to my CTC DiY I3 3D printer.<br><br />
Here's an Arduino sketch to bench test a BLtouch/3Dtouch (or clone) levelling sensor, that lets you set probe states by single letter serial commands and reports the ZMIN output status, like this:<br><br />
<br />
*** BLtouch/3Dtouch probe tester ***<br />
D = Deploy<br />
T = Tswitch<br />
R = Retract<br />
S = Self test<br />
A = Alarm off<br />
? = read ZMIN<br />
The Arduino LED echoes the ZMIN state, ON=High / OFF=Low<br />
__________________________________________________________________<br />
________________#___________________________________#_#___________<br />
____________________###______####_______##########_________####___<br />
____####__________________________________<br />
ZMIN is Low (0.10V)<br />
____________________________######################################<br />
ZMIN is High (5.00V)<br />
#################_________________________________#_______________<br />
<br><br />
The sketch: [[File:BLtouch tester.zip]]<br />
<br />
=== 29 June 2022 - Mounting the BLtouch, and building Marlin to support it ===<br />
Slight progress on adding a BLtouch (clone) ABL sensor to my Zuhai CTC DiY I3, 3D printer. I've got the probe bracket printed and the BLtouch mounted on my printhead, with only 26mm Y offset, and nearly no X offset, without blocking access to the top of the throat in case of filament problems.<br><br />
<br><br />
''I drilled two 3mm holes just in from the front edge of the L bracket that holds the print head assembly to the X gantry carriage, in front of the mounting block that holds the hotend, to fix the bracket to with 2.5mm self-tappers from underneath into the printed probe bracket. My bracket was a little too low for the optimum probe height relative to the nozzle tip (above the tip by half the probe extension), so I ended up shimming it with a piece of wooden coffee stirrer. Once I touched it in with a black marker, you wouldn't know the shim is there, so although I fixed my OpenSCAD' bracket model, I'm going to be lazy/frugal and not re-printt it'<br> <br />
<br><br />
My printer uses an ANET3D v1.5 controller, so I've only got 128K FLASH on the ATmega1284P MCU to play with (half that on the usual ATmega2560 based boards), which has made building Marlin 1.1.9 small enough to fit with AUTO_BED_LEVELING_BILINEAR and BLTOUCH enabled quite a challenge.<br><br />
Even with aggressive GCC optimizations, (see links section below) it didn't quite fit until I disabled the boot screen. It was a choice between that and ditching Optiboot. :( <br />
Sketch uses 129932 bytes (99%) of program storage space. Maximum is 130048 bytes.<br />
Its a 'full fat' Marlin v1.1.9, with full menu, SD support and all the other nice to have goodies enabled., and I've still got 116 bytes left for any tweaks I want to add! 😁 <br><br />
<br><br />
''Petr Cecil: Just keep important features like thermal runaway protection on in marlin so you don't burn your home :))''<br />
<br />
''Yes, keeping thermal runaway protection was my highest priority. Without it, you are one loose screw away from a house fire! Many thanks to Petr for letting me use his crimper and JST connector parts to make up a JST XH-3 cable I badly needed for my BLtouch install. For anyone else needing JST XH (and duPont) crimping capability, here's what Petr recommends:'' <br />
https://www.amazon.co.uk/gp/product/B07VX6YGQ8/ ''and having used it, I would also recommend it.''<br><br />
<br />
=== 1 July 2022 - Wiring the BLtouch probe ===<br />
I've got most of the recabling done on my CTC DiY I3 for the BLtouch probe. I've spliced a three wire breakout cable for +5V Gnd and servo signal into my display ribbon cable, and re-done the loom to the printhead to add the BLtouch extension cables. All that's left to do is assemble the adapter board that Petr helped me with the JST cable for, mount and wire it, flash a BLtouch enabled Marlin build, and then I'll need to calibrate the Z offset.<br><br />
<br><br />
[[File:BLtouch combiner board.png|thumb]]<br />
... and here's the circuit I intend to use to combine use of the regular limit switch which is set up to inhibit Z movement approx half a mm below the bed surface (less than the flex in the gantry) so it cant 'dig for Australia' if for any reason the BLtouch wasn't deployed before homing.<br><br />
<br><br />
''I constructed the combiner board on Veroboard, laying it out using [https://veecad.com/ VeeCAD], from the schematic I drew up in [https://www.tinycad.net/ TinyCAD], mounted it to the printer and wired it up.''<br />
<br />
=== 5 July 2022 - Visualizing the bed levelling mesh ===<br />
Meanwhile, I've been futzing around with visualising 3D printer bed levelling meshes from Pronterface *without* pasting the M420 V mesh data into a website. Marlin comes with an OpenSCAD mesh visualiser called [https://github.com/MarlinFirmware/Marlin/blob/1.1.x/buildroot/share/scripts/MarlinMesh.scad MarlinMesh.scad], and it turns out that all you need to do to get external mesh data into that is to pass it in on the OpenSCAD command line as variables defined by -D override variables with file scope defined in the file. <br />
<br />
The prerequisites for using it are explained here, but if you've already got OpenSCAD installed and are using mesh bed levelling, you'll only need to skim this: https://3dwork.io/en/visualize-3d-mesh/<br />
<br />
To do this from Pronterface, with a hard coded mesh, as I hadn't figured out the M420 mesh parsing yet, put MarlinMesh.scad in the printrun directory and (on windows) in Pronterface send:<br />
<br />
!os.system('start /max "" "C:\Program Files\OpenSCAD\openscad.exe" MarlinMesh.scad -D $vpd=800 -D measured_z= <br />
[[-0.086,-0.045,-0.037,-0.046,-0.167,-0.292,-0.421],[+0.034,+0.038,-0.002,+0.017,-0.017,-0.121,-0.413], <br />
[+0.122,+0.098,+0.162,+0.034,-0.069,-0.234,-0.472],[+0.205,+0.196,+0.120,+0.071,-0.007,-0.149,-0.467], <br />
[+0.175,+0.174,+0.102,+0.010,-0.130,-0.313,-0.587],[+0.194,+0.189,+0.116,+0.034,-0.042,-0.170,-0.568], <br />
[+0.128,+0.089,+0.032,-0.033,-0.168,-0.373,-0.594]]')<br />
<br />
Note that this is currently Windows only, as the os.system() command string to launch OpenSCAD and return immediately:<br />
'start /max "" "C:\Program Files\OpenSCAD\openscad.exe" '<br />
will be very different under LINUX or OSX. The rest of the command line should be the same.<br />
<br />
Also I would strongly recommend editing the default mesh in MarlinMesh.scad (lines 24-30) to be a minimal 'null' mesh:<br />
measured_z=[[0,0],[0,0]]; //minimal mesh<br />
to make it obvious if your mesh data hasn't been passed in successfully.<br />
<br />
ToDo: Write a script to send G420 V to the printer and parse the returned mesh data into a string containing the mesh in the above OpenScad list of lists format, that can simply be appended to the os.system() command line after the -D measured_z=<br />
<br />
''Later that evening:''<br><br />
I've written and tested the Pronterface macro to launch MarlinMesh.scad from Pronterface with the printer's current MBL mesh from a M420 V report of the form:<br />
Bilinear Leveling Grid:<br />
0 1 2 3 4 5 6<br />
0 -0.086 -0.045 -0.037 -0.046 -0.167 -0.292 -0.421<br />
1 +0.034 +0.038 -0.002 +0.017 -0.017 -0.121 -0.413<br />
2 +0.122 +0.098 +0.162 +0.034 -0.069 -0.234 -0.472<br />
3 +0.205 +0.196 +0.120 +0.071 -0.007 -0.149 -0.467<br />
4 +0.175 +0.174 +0.102 +0.010 -0.130 -0.313 -0.587<br />
5 +0.194 +0.189 +0.116 +0.034 -0.042 -0.170 -0.568<br />
6 +0.128 +0.089 +0.032 -0.033 -0.168 -0.373 -0.594<br />
echo:Bed Leveling Off<br />
echo:Fade Height Off<br />
<br />
[[File:Bed mesh.png|thumb|My poor bed looks like a map of the Himalayas!]]<br />
So I've now got a Pronterface button that visualizes my bed live, without resorting to an online bed visualizer WWW site. 😁<br />
<br />
''Even with ABL enabled, its useful to let you see if your whole bed is out of whack' and could benefit from adjusting its levelling screws to reduce the range of Z offsets the ABL has to compensate for.'' <br />
<br />
It is currently Win x64 only, as the command line to launch OpenSCAD is OS specific. It shouldn't be hard to change that for Linux or OSX.<br />
<br />
To add it to your own Pronterface, first put MarlinMesh.scad in your Printrun folder, then paste the following into a new Pronterface macro:<br />
<pre><br />
!################# Bed Visulization macro #################<br />
!# Pronterface script to invoke OpenSCAD MarlinMesh with #<br />
!# the current MBL mesh returned by M420 V. #<br />
!# #<br />
!# (c) Ian.M 7/7/2022 #<br />
!# #<br />
!# "THE BEER-WARE LICENSE" (Revision 42): #<br />
!# "Ian.M" <https://t.me/Ian_M_2019> wrote this stuff. #<br />
!# As long as you retain this notice you can do whatever #<br />
!# you want with this stuff. If we meet some day, and #<br />
!# you think this stuff is worth it, you can buy me a #<br />
!# beer in return. Ian.M #<br />
!##########################################################<br />
!<br />
!import time<br />
!import os<br />
M420 V ; requst ML grid<br />
!time.sleep(1) # wait for it<br />
!idx=len(self.p.log)-1 # get last line in log buffer<br />
!idxf=None # error value <br />
!idxl=None<br />
!for x in range(idx,max(idx-20,0),-1): # iterate backwards <br />
! if self.p.log[x].find("Grid:")>8: # looking for 'Grid:', if found:<br />
! idxf=x+2 # set idxf to first (real) line of grid <br />
! break; # and exit loop<br />
! if self.p.log[x].find("echo:")==0: # looking for 'echo:', if found:<br />
! idxl=x-1 # set idxl to previous line till last line of grid is found<br />
!<br />
!#print("Debug: range "+str(idxf)+", "+str(idxl))<br />
!<br />
!if (idxf is None) or (idxl is None): # M420 failed<br />
! self.logError("Error: M420 failed")<br />
! return<br />
!if idxf>idxl: # M420 no grid<br />
! self.logError("Error: M420 did not return a grid")<br />
! return<br />
!<br />
!mesh="["<br />
!for x in range(idxf,idxl+1): # build list of OpenScad lists<br />
! mesh=mesh+"["+str(self.p.log[x])[3:].rstrip().replace(" ",",")+"]" # build comma separated list<br />
! if x<idxl:<br />
! mesh=mesh+"," # more to follow<br />
! else:<br />
! mesh=mesh+"]" # last one - end outer list<br />
!<br />
!# Build MMcmd for OpenSCAD installed in default location on 64 bit Windows.<br />
!# N.B use explicit 64 bit Program Files directory as Pronterface is a 32 bit application,<br />
!# so %ProgramFiles% returns %ProgramFiles(x86)%, which is the wrong folder.<br />
!MMcmd='start /max "" "%ProgramW6432%\\OpenSCAD\\OpenSCAD.exe" ' # change this OS dependent stuff!<br />
!MMparams="MarlinMesh.scad -D $vpd=800 -D measured_z=" # OpenSCAD command line parameters<br />
!# n.b. MarlinMesh.scad must be in printrun working directory<br />
!# -D defines an OpenSCAD constant for the session, overriding variables within the file. <br />
!<br />
!print("Invoking MarlinMesh.scad with this mesh.")<br />
!print("Exec: "+MMcmd+MMparams+mesh)<br />
!os.system(MMcmd+MMparams+mesh) #Execute it<br />
</pre><br />
<br />
''Edit: It turns out, that depending on your Pronterface version, you'll probably need to import '''os''' and '''time''' at the top of the macro. I've added them above.''<br />
<br />
=== 10 Sept 2022 - Z-screw wobble isolation ===<br />
Back in January I wrote:<br />
<blockquote><br />
The original rigid couplers between the Z stepper motors and the Z screws were unsatisfactory, as any misalignment directly pushed the gantry laterally resulting in prints with pronounced Z banding. I therefore bought some helical flexible couplers for coupling 5mm to 8mm shafts, and installed them with a 7mm ball bearing inside each to transfer the axial thrust loading from the Z screws direct to the motor shaft to minimize Z bounce. I had to shim the lead screws (which are ordinary M8 allthread) with aluminum cut from a drink can to get them concentric in the 8mm end of the coupler as their OD is slightly undersize.<br />
<br />
Although there was a notable improvement in print quality once I had carefully adjusted the coupler alignment, it wasn't a total cure as the lead screws are still shimmying enough to wobble the gentry at low Z heights. I need to decouple the drive nuts from the gantry, by flipping them the other way up and adding a thrust bearing that doesn't constrain them radially between them and the gantry. The nuts will also require anti-spin arms, and as the screws will no longer have any constraint above the couplers, they'll need top bearings.<br />
</blockquote><br />
<br />
At long last, I've completed the next stage of this, by laser cutting new top brackets and bearing retainers for 688ZZ ball bearings (8mm ID, 16mm OD, 5mm wide) from plywood, consisting of a redesigned bracket in 5mm ply, with a 16mm hole for the bearing which fits flush, surrounded by six tiny holes to fix retaining rings cut from 3mm ply above and below the bracket, each held by three tiny 2mm screws. I also laser cut the anti-spin arms for the Z-nuts from 5mm black Acrylic. All ply parts were spay painted matte black to match the rest of the printer frame. A Thursday evening well spent.<br />
<br />
I installed the parts and after some fiddling around managed to reduce the Z-screw runout, and got the screw centered well enough in the gantry end nut mounts not to touch and jerk. I still haven't got proper thrust bearings, and am making do with a stack of three M10 washers on the long end of each Z-nut, which have *NOT* been flipped as originally planned, as it looks like I'll need something other than the Z-screw to loosely constrain the thrust bearing. The washers are lightly greased so can slide over each other fairly readily<br />
<br />
After re-leveling (and some BLtouch calibration issues that were borking my first layer height), I finally managed to print a good test cube. Its got much less pronounced Z banding than before this upgrade. Hopefully adding ball thrust bearings will eliminate most of the residual banding. ToDo: design & fabricate cages for these bearings. The problem is a lack of space - I haven't got a lot of height between the top of the coupler and the bottom of the nut, and also, anything much larger than the 22mm OD of the nut flange would force me to move the part cooling fan and redesign its duct.<br />
<br />
''OpenSCAD design files and photos to follow''<br />
<br />
=== 06 January 2023 ===<br />
Another hiatus - I didn't need to do any 3D printing and was busy learning the RML mini-lathe.<br />
However I've made a small but significant improvement to the Z axis with nothing more than a few square cm of waxed paper! I took the backing paper off some double-sided tape, and wrapped one turn of the paper round the Z screw to make a spacer to fit inside the stack of washers. It sits over the lip on the end of the nut, inside the ID of the washer stack and helps the washer stack stay centered on the screw so none of them touch the screw, catch and jerk, but is so flimsy that the washers can still slide laterally with minimal extra force on the X gantry. A test cube showed much reduced Z banding vs the previous one from October.<br />
<br />
Its still not good enough as there is far too much runout at the bottom of the right-hand lead-screw which is shifting the X gantry support force to and fro enough to wobble it. Either I've got a bad coupler, its poorly assembled or there is a kink in the end of the screw where it was cut. Probably the best option will be to chuck the leadscrew in a soft collet in the lathe, get it running true, then turn the thread off the end of the leadscrew, shrink on a short bored out piece of steel rod, then turn that to 8.00 mm diameter, concentric to the screw, so I'm no longer trying to clamp on the threaded end.<br />
<br />
=== 13 December 2023 - Better Leadscrew Concentricity ===<br />
Some 3D printing of small parts this year, and several false starts with improving the lead screws. I spent quite a bit of lathe time doing test pieces with short lengths of M8 allthread. <br />
<br />
The soft collet idea was a non-starter as anything that grips on the thread tips gives poor concentricity. It turns out the answer is to wind a helix of soft iron or mild steel wire that fits the thread and grip on that so the grip is on the flanks of the thread. Also, shrink fitting was a bust - the precision and surface finish required to make it work for such small parts is right at the limit of RML's capabilities, and the tiny thermal mass gives only seconds to fit it and a fraction of a second to slide it home. The answer was loctite + machining to a push fit. 11 mm long, ~5.6 mm bore steel sleeves were made from 3/8" (9.5 mm) stock, and the thread turned down to fit for ~11 mm from the screw end. We don't have good enough bore measuring capability at RML so a test plug was turned to fit drilled bore to get the diameter to work to. Loctite was applied to both surfaces and the sleeve tapped on firmly. The OD was then turned to 8.00 mm and faced to 10 mm length, just cleaning up the screw end to get a true uniform end face, and the edge chamfered. <br />
<br />
I've got one leadscrew done, but time and machining mistakes were against me (I screwed up the 8.00 mm OD and had to turn the sleeve off and re-do it) so didn't get the second screw done. That's a job for tomorrow. <br />
<br />
Fitting and removing the screws now requires top corner plate removal. Run the gantry right up and hang it from the frame, then run the Z-nuts and their anti-rotation arms back down. Undo the coupler and take off the corner plate. The guide rod can be lifted and the anti-rotation arm swung clear, then the bottom end of the screw can be lifted off and slid down and forward till it can be slid out of the gantry end. Refitting is the reverse of removal.<br />
<br />
I've already got the left Z screw fitted, and the result is no obvious runout. Its highly dependent on the tightening sequence of the lower part of the helical coupler as excessive pressure with the split clamp causes the D shaft to go off center, so that should be lightly snugged up then the grubscrew tightened firmly on the flat. The grubscrew must be well aligned with the flat. Turn the other Z motor shaft to turn the one being assembled for access to the screws, as the coupler initially wont be tight enough to turn the motor.<br />
<br />
=== 15 December 2023 ===<br />
I machined the other screw yesterday evening and fitted it this morning, again with no obvious runout. I did some manual levelling to get the bed as near true to the Y rails as possible and the X gantry true to the frame and hopefully to the bed, then started automatic bed levelling.<br />
<br />
== - more to follow - ==<br />
<br />
== Some useful links ==<br />
* https://github.com/ralf-e/ANET-3D-Board-V1.0 - Schematic for an earlier version of the controller, near enough the same as the v1.5, and for the LCD2004 display/buttons board. Note that connector pinouts should be checked against the actual board before trusting them. e.g. I know the end stop connectors have pins 1 and 3 swapped vs the schematic.<br />
<br />
* http://lokspace.eu/anet-a8-wifi-mod/ - How to add printing over WiFi using an ESP-01 ESP8266 WiFi module and esp-link, by populating the Anet3D 'USB BLE' header + removing two zero ohm resistors. Level shifting is needed to get the 5V level ATmega TX pin down to 3.3V levels for the ESP8266 RX pin, hence the resistors on the carrier board. There's also no need for a USB UART adapter to flash the ESP8266, as the ANET main board has one of those. After dong the mainboard mod, simply take two short duPont F-F jumpers and link opposite corner pins of J8 the 'USB BLE' header, and use the mainboard's USB port. After flashing, remove the duPont wires, fit two jumper caps in the BLE position, and carry on with esp-link setup. Alternatively, use a Wemos D1 Mini clone which has all you need on-board except the level shifter, and its simple enough to solder two resistors for that. See my page [[WiFi 'tethered' Arduino robot]]<br />
<br />
* https://docs.arduino.cc/software/ide-v1/tutorials/PortableIDE - how to set up a portable install of the classic Arduino IDE which is strongly recommended for any existing Arduino user for building Marlin 1.1.x as you are likely to need to down-version the core and various libraries.<br />
<br />
* https://spiritdude.wordpress.com/2018/03/26/ctc-diy-prusa-i3-ctc-diy-i3-pro-b-most-affordable-3d-printer-2018/ - Another user's experiences with this printer.<br />
<br />
* https://ufj.ddns.net/blog/marlin/2019/01/07/reducing-marlin-binary-size.html - Turning on aggressive AVR GCC optimizations to reduce the size of the Marlin firmware, so it will fit in 128K program memory without having to prune too many desirable features.<br />
<br />
* https://all3dp.com/2/epic-3d-printing-fails-and-why-they-failed/ - some of the many ways things can go badly, ranging from potentially life-threatening, down through expensive and tedious, to mildly amusing.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_%C2%A399_ZHUHAI_CTC_DiY_I3_3D_printer&diff=17596Ian M's £99 ZHUHAI CTC DiY I3 3D printer2023-12-13T16:40:09Z<p>IanM: /* 06 January 2023 */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br><br />
<br />
The ZHUHAI CTC DiY I3 Pro B 'Prusa' clone printer is rather similar to RML's [[Geetech I3 Pro B]] except with a laser cut plywood frame instead of acrylic, and cheapened in many key areas, which I'm working on upgrading. Its my personal 3D printer and is not kept at RML.<br />
[[File:Ian's CTC I3 After BLtouch upgrade.jpg|thumb]]<br />
== The DiY kit and the build ==<br />
Here's CTC's official build video: https://youtu.be/PSzcU48wczk<br />
=== Differences on my printer ===<br />
* IEC power inlet (Video has direct attached mains lead)<br />
* Bed levelling screws have countersunk heads so there are no obstructions at the bed corners<br />
<br />
=== Hints & Tips that didn't make it into the build log ===<br />
* Buy a pack of M3 washers and insert one in each T-slot in the frame, between the nut and the wood it bears on, to spread the pressure and prevent the nut chewing the wood.<br />
<br />
* A pair of M8 nuts can be used to 'hang' the lead screws and gantry assembly from the top of the frame while working on the steppers or shaft couplers.<br />
* Put a *VERY* large cable tie right round the body of the extruder and X steppers, with the tail coming straight up at the back of the extruder, and straight down off the X stepper, then cable tie the wiring to the big tail to anchor it before you spiral wrap, Leave the big tail full length inside the spiral wrap to stiffen the loom near the motor. A similar large cable tie round the lower right board fan standoff, snug but not tight so it can pivot on the standoff, can be used to anchor the lower end of the X loom.<br />
<br />
* The 2004 control/display PCB is probably being warped by its plywood frame and the absence of spacers between the board and the back not allowing for the solder joints with slightly protruding header pins. Dismantle it and shim for clearance behind the board with nuts/washers/etc. taking care not to short anything. You may need to file out the bolt holes in the ply so the board fits properly without being forced into a curve before reassembling and mounting it.<br />
<br />
== Build log from my posts on the RML Telegram group ==<br />
''Currently, a mostly verbatim copy of my 3D printer related posts, with some corrections and additions to my posts + some responses to my posts from other members. If you feel I've misrepresented what you said, or you don't want to be quoted, and you don't have edit rights here, PM me on Telegram!''<br><br />
<br><br />
''ToDo: Transfer more stuff from Telegram here and edit it into a coherent project writeup.''<br />
<br />
=== 6 Jan 2022 - Arrival and initial mechanical assembly ===<br />
A cheap (£99) Prusa i3 clone 3D printer kit should be landing on my doorstep later on this afternoon . . .<br><br><br />
{<s>photo from manual</s>, ''not posted here due to copyright''}<br><br><br />
It arrived.<br><br />
Its actually a ZUHAI CTC DiY I3 PRINTER with a wooden frame, and an ANET A8 v1.5 clone controller board. That’s more or less what I expected as a *real* Prusa for under a ton just isn't happening unless its a BER parts mule. Next: dig through the documentation, such as it is . . .<br><br />
<br><br />
''Mike: “Hi Ian, is it £99?”''<br><br />
<br><br />
Yep. It was £99 from Amazon. https://www.amazon.co.uk/gp/product/B015GDDXJA<br />
<br>I've done the full mechanical assembly, and knocked off for the night *WITHOUT* starting any wiring.<br><br />
<br><br />
For anyone else contemplating this one, beware: the rails are steel tube, not rod, it has plastic slider bushings not linear bearings, and the Z drive nuts are aluminum, not bronze or brass. Also the filament drive is not adjustable for pressure, and there are very few free GPIOs on the controller available for custom stuff. (There's the three SPI pins of the ISP port J3 ''if you disable SD card support'', one pin on the LCD connector reserved for a beeper on some display boards, and I suppose you could free up two more analog capable pins and UART1 TX & RX if you added an I2C LCD driver board.)<br><br />
<br>[[File:Ian's CTC I3 IEC Boot + extra clamping nuts on Y strut.jpg|thumb]]<br />
* '''CAUTION: THERE ARE EXPOSED MAINS TERMINALS'''<br><br />
As soon as I've got it dialled in I need to print a cover for the back of the IEC connector, and do something better than the flip-up cover over the PSU mains terminals. ''I ended up putting a rubber boot made from bicycle inner tube over the back of the IEC connector secured with cable ties as it was just too unsafe adjusting the right rear bed levelling screw without insulation there.'' <br><br />
<br><br />
I've already improved the rigidity considerably by adding four M8 nuts and washers to clamp the vertical frame to the M8 allthread that joins the front and back end plates. If you do the same, you *MUST* align the frame and endplates on a dead flat surface<sup>'''*'''</sup>, and as you tighten the new nuts, use a straightedge to check you aren't bowing the vertical frame's lower cross-member. Check you get the front on again dead square. While you are in there, put a nut in the hex hole in the Y axis belt tensioner so the bolt stays put while you adjust the wing nut.<br><br />
<br><br />
I'm sure I'll be buying other bits for it, once its up and running. e.g. flexible couplings + bearing balls for thrust for the Z screws to reduce shimmy, cheap but real linear bearings, and an all metal adjustable pressure filament drive upgrade kit.<br><br />
<br><br />
'''''<nowiki>*</nowiki> The flatness of the assembly surface is crucial - 0.2 mm lift of one side of the front plate relative to the rest of the frame, becomes 0.1 mm of varying bed tilt as the bed moves from min. Y to max. Y or visa-versa, giving the illusion the bed surface is saddle shaped, but also resulting in increasing lateral distortion the greater the print height is above the bed rails. Once assembled flat and true, it *should* be operated on an equally flat surface to maintain alignment, but if your table is of questionable flatness, the printer can be shimmed under its frame, and front and back plates to maintain six points of contact, and its position on the table marked to remind you to keep it in the position you've shimmed flat for it.''''<br><br />
<br><br />
<br />
=== 9 Jan 2022 - Wiring and problems ===<br />
Doing the CTC I3 3D printer wiring neatly took most of Saturday afternoon. Then it didn't work! 😢<br><br />
''Back in January, the extra board above the main board (to combine the normal Z limit switch and the BLtouch probe output), and all wiring to it was not present, and only the standard single short-lever Z limit microswitch was fitted.''<br />
[[File:Ian's CTC I3 Boards and Wiring.jpg|thumb|The main board and wiring]]<br />
<br><br />
Diagnosing its ills took the whole evening - one of the Z steppers had a broken wire. After carefully teasing the offending pin out of the stepper cable connector, I cleaned out the old crimp and soldered it and both steppers stepped uncoupled. It helps to use a couple of M8 nuts, put on the tops of the Z screws to hold them up so the X axis doesn't have to be dismantled when working on the Z steppers and couplings. The left side was binding and the right side wasn't a whole lot better. Turns out the laser cut bracket motor mounts don't line up with the screw when the Z axis is near the bottom. It’s fiddly but it is possible to remove the motors without extra dismantling. Some careful filing to elongate the mounting holes to line up the motor and final tightening after the coupling was slid over the screw end, and it no longer binds.<br> <br />
<br><br />
However, it still failed to home. 😾 Investigating the limit switch signals found the odd one out was the Y axis which read as homed when it wasn't. The switches are all NC microswitches, and I was getting ready to replace it, when I found its connections failed the tug test on both wires! The wires were broken under enough OEM heatshrink to confuse the issue. Resoldering them and applying new heatshrink fixed that and it now homes.<br><br />
<br><br />
I suspect the motor wire was a bad crimp, and the switch wires most likely broke because they were 'flapping in the breeze' while the bed, Y axis and lower frame assembly was being packed and shipped.<br><br />
<br><br />
Finally I was able to test the full range of motion of all axes, do a quick & dirty manual bed levelling and set the Y zero limit screw as low as seems reasonable. (I had it high to avoid crashing the nozzle earlier.) Selecting PLA warmup showed both the heated bed and the hot-end were working, and stabilized at their setpoints, though I'm getting an initial 10 deg C overshoot during hot end warmup, so it probably needs some tuning.<br><br />
<br><br />
I then tried to load and feed filament - no joy - it didn't want to feed, and when I manually encouraged it all I got for my trouble was a clogged hot-end. Taking the extruder off, dismantling it and careful reassembly of the feeder got it feeding, but I still had the clog to deal with.<br> <br />
<br><br />
I suspected the PTFE tube liner in the heat-break wasn't seating properly, which is what probably caused both the feed problem and the clog. I dismantled the hot-end and extracted the PTFE tube - clogged solid and fatter than the throat at the top of the heat-break tube. I managed to press the clog out with the stem of an Allen key, then close inspection of the PTFE tube found neither end was square. I shaved the better end square, and chamfered the entry to the other end by twiddling a sharp drill bit to stop the filament catching on its edge. Clearing the nozzle was a PITA, eventually it succumbed to a cold pull done off the hot end, supporting the nozzle with a small ring spanner and heating it with a lighter.<br><br />
<br><br />
I then bench tested the extruder, and it now feeds and extrudes, (manually using the axis menu). Its really fiddly to bolt back on to the X carriage without stripping it to separate the bracket, but after a lot of faffing about and some rather unparliamentary language I got it back on properly, leaving it loaded with filament from the bench test.<br><br />
<br><br />
Finally I checked it still homes and that the bed levelling hadn't gone too far out while I was working on it, and shut it down for the night.<br><br />
<br><br />
ToDo: Try printing something!<br><br />
<br><br />
<br />
=== 9 Jan 2022 - Q&A with Ian B, dangerous mains plug, and sellers 'bait & switch'! ===<br />
''Ian B: “Ian, that's quite a log of problems solved. It certainly shows a lack of QC from the manufacturer.''<br><br />
<br><br />
''It seems you've approached each fault methodically. (I would expect nothing less from you.) Heating the extruder with a lighter is something I've never heard of before, useful technique.''<br> <br />
<br><br />
''I wish you luck with the first print. Keep it small and simple.''<br><br />
<br><br />
''Then I wish you ongoing luck with all subsequent prints, too.”''<br><br />
<br><br />
If you try my lighter trick, to avoid bouncing a hot-ish nozzle round the room, it would probably be a better idea to screw the nozzle into a M6 nut, and hold it in mole grips with card for thermal isolation from the grips, and clamp the grip handles flat in a vice. The nut will also increase the thermal mass making the whole process more controllable.<br><br />
<br><br />
I forgot to mention the illegal ('The Plugs and Sockets etc. (Safety) Regulations 1994' - UK Statutory Instruments 1994 No. 1768) undersized and unfused mains plug on its supplied IEC lead. Its pins were so far undersize that there was no retention force in a standard socket!<br><br />
<br><br />
John Ward on these counterfeit leads & plugs: https://www.youtube.com/watch?v=9KMrWupFQt4<br />
<br><br />
AITA if I try to nail Amazon's balls to the wall for "not as described" and the illegal mains lead? It was still a reasonably good deal as supplied . . .<br><br />
<br><br />
==== Description from Amazon product page at time of sale ====<br />
* Brand Josef Prusa<br />
* Material Carbon Fibre<br />
<br />
'''Product description - Technical specifications'''<br />
* Print area - 8x8x8 inches (20x20x20 cm)<br />
* Open frame design for easy use<br />
* Integrated LCD for use without a computer<br />
* SD card support (8GB included) and USB port<br />
* Geniune E3D 1.75mm hotend and RAMBo mini motherboard<br />
* Easy multicolor printing feature based on layer height<br />
* Layer height from 50 microns<br />
* Heated print bed for warpless printing from any material<br />
* Supported materials - PLA, ABS, PET, HIPS, Flex PP, Ninjaflex, Laywood, Laybrick, Nylon, Bamboofill, Bronzefill, ASA, T-Glase, Carbon-fiber enhanced filaments...<br />
* Step size in X/Y axes - 10 micron<br />
* 2 lbs (1 kg) Silver PLA included<br />
<br />
==== DISCREPENCIES (so far) ====<br />
* Not a genuine Josef Prusa printer - its a ZHUHAI CTC ELECTRONIC CO. model.<br />
* Plywood frame, and no carbon fibre components<br />
* Less than 20cm X travel - measured 18.6cm from mechanical limit to limit<br />
* No SD card supplied<br />
* Not a "Geniune (sic) E3D 1.75mm hotend" - its got a bargain basement generic clone hotend<br />
* Not a "RAMBo mini motherboard" - its got an Anet A8 v1.5 clone, with a lesser MCU, no max. endstop switch inputs, one less thermistor input, and only three PWMed MOSFETs, so only one controlled fan can be connected.<br />
* No "2 lbs (1 kg) Silver PLA included" - Three sample coils of approx 12m each, total under 120g supplied<br />
<br />
=== 12 Jan 2022 - First Print and another defect found ===<br />
The CTC I3 3D printer prints!<br><br />
<br><br />
I'm currently using Cura 3.2.1, and so far have done a test cube and am currently trying an Arduino Mega2560 'bumper' generated from an OpenSCAD library. I aborted the first run after a couple of layers to have something to check against the Arduino board - it looks reasonable, so I'm doing a proper run, and hoping it comes out well enough to use. <br><br />
<br><br />
More defects found! The X tensioner bolt has a really crappy rolled thread and wont hold in the wing-nut. An ordinary M3 nut on it has just enough grip to be usable. I need to replace it with a long M3 machine screw, so I can get a nut into the tensioner body to hold it, so it doesn't spin when I adjust the wing nut. ''Subsequently fixed with a length of M3 stainless allthread, with the end mushroomed slightly and a hex nut Loctited on flush to effectively make that long machine screw.''<br><br />
<br><br />
Next job will be to see if I can backup the existing firmware then look at what it takes to get Marlin built for an Anet A8 v1.5 controller, and configured for the CTC I3 3D. Once I've got a usable 'stock' firmware, I can look at the upgrades I want to do, as even swapping out the extruder's filament drive mechanism would need me to reverse the extruder motor (due to the handedness of the drive assembly required to clear the mounting bracket). ''I did succeed in making a backup using AVRDUDE and a PICkit 2.''<br><br />
<br><br />
Edit: The Arduino 'bumper' is usable - a bit tight, so either my X and/or Y scaling is fractionally off or the Elegoo Mega2560 clone PCB is fractionally oversize.<br><br />
<br />
=== 17 Jan 2022 - Running my own Marlin build and finding/fixing more mechanical defects ===<br />
Progress of a sort on the CTC DiY I3 3D printer . . .<br><br />
<br><br />
The stock firmware is fairly sucky, ''probably doesn't have thermal runaway protection,'' and CTC don't appear to have released their source :( so I've been working on configuring a Marlin 1.1.9 build to run on it. Its only got an ATmega1284P ''(which has 128K Flash program memory)'', and I'm currently at 95% used, so Marlin 2.0.x isn't really a good option as I'd have to pare it down too much. Unfortunately those who have been there before me had a DiY I3 with a different controller so its been a fight to hack the config files into a usable state for it. I've still got some FUBARed Z motion defaults I need to sort put before it tries to get the Z axis to dig for Australia again! Maybe I should restore the backup of the original firmware and time some motions . . .<br><br />
<br><br />
In other news, there is supposedly no calibration table for its thermistors that's usably close, so I've had to generate one fudged from an Excel spreadsheet and some dodgy temperature measurements taken with a 1N914 diode stuffed up the hot end<br><br />
''My life was complicated here by the lack of any thermometer that could survive hot end temperatures.''<br> <br />
<br><br />
Bed Levelling needs some work, I'm trying to get manual mesh levelling up and running but it really *HATES* concave beds, as there is no option to automate moving to a safe height to clear the edge after homing off the edge of the bed. Various kludgy firmware hacks have been proposed, but I think a hardware hack is in order - use the Ymin limit switch to switch in a different height Zmin limit switch when its not over the bed, so it can be adjusted to home at a height that skims just clear of the [0,0] bed corner, then can go -Z by up to a mm or so before the regular Zmin limit trips, to allow it to level mesh points 'in the valley' without a Z probe.<br><br />
<br><br />
To that end, has anyone got a *looooooooong* lever SPDT microswitch hanging about? Flat lever and 20mm 2 hole body with terminals on the bottom preferred. Also, ideas for a cheap-skate Z probe wouldn't go amiss.<br><br />
<br><br />
''In the end I found some suitable switches on Amazon and built my dual switch Z axis limit 'Z-hop' mod. It fits in place of the original switch and if homing, with the nozzle just off the front of the bed provides a Z limit a little over 0.5mm higher than that over the bed, with the difference adjustable by bending the long switch lever. Some months later I found a BLtouch Z probe clone far cheaper than I could build any sort of deployable probe.''<br><br />
<br> <br />
Also, has anyone got experience automating acquiring temperature calibration table data for Marlin? I'm thinking maybe a Type K thermocouple bonded into a knackered brass extruder nozzle with high temperature cement, and some sort of PC interface for it, talking to Marlin with M105 SHOW_TEMP_ADC_VALUES enabled. Take it up in steps, reading the ADC and temperature for each till its good & hot, then log the cooling curve and check it matches reasonably well, and finally spit out a table in Marlin header file format.<br><br />
<br><br />
* '''CAUTION: Belt tensioners destroy themselves!'''<br />
The idiots at CTC used D shaft offcuts for the belt tensioner pully shafts and used the drive type pully for the idlers so the shaft turns with the pully. Running in a plastic hole with no bushing it acts as a D reamer and tries to chew its way back to the motor! A reasonable bodge fix is to flatten four M5 split washers ''(two for each tensioner)'', and wedge them in the recesses either side of the tensioner body, with the splits towards the tension screw. That's steel on steel, but if kept greased is better than steel D reamer on plastic! Long term it needs decent ball bearing tensioners. ''[[#18 June 2022 - Upgrading the belt tensioners with ball bearings|See below.]]<br><br />
<br />
=== 20 Jan 2022 - Flexible Z screw couplers ===<br />
The original rigid couplers between the Z stepper motors and the Z screws were unsatisfactory, as any misalignment directly pushed the gantry laterally resulting in prints with pronounced Z banding. I therefore bought some helical flexible couplers for coupling 5mm to 8mm shafts, and installed them with a 7mm ball bearing inside each to transfer the axial thrust loading from the Z screws direct to the motor shaft to minimize Z bounce. I had to shim the lead screws (which are ordinary M8 allthread) with aluminum cut from a drink can to get them concentric in the 8mm end of the coupler as their OD is slightly undersize.<br />
<br />
Although there was a notable improvement in print quality once I had carefully adjusted the coupler alignment, it wasn't a total cure as the lead screws are still shimmying enough to wobble the gentry at low Z heights. I need to decouple the drive nuts from the gantry, by flipping them the other way up and adding a thrust bearing that doesn't constrain them radially between them and the gantry. The nuts will also require anti-spin arms, and as the screws will no longer have any constraint above the couplers, they'll need top bearings.<br />
<br />
I also added a silicone 'sock' over the hotend to improve its insulation and reduce the hot touch hazard to just the nozzle itself.<br />
<br />
=== 10 Feb 2022 - Upgrades ===<br />
CTC DiY I3 3D printer progress: All slider bushings have been replaced with real linear bearings and I'm now printing a 3DBenchy in black PLA on 1.8mm glass (cut from a broken picture frame), with cooling<sup>'''*'''</sup>, using Cura 3's 'stock' slicer settings: Fine (0.1mm layers, 20% infill). So far its looking good.<br><br />
<br><br />
I need to do something about a proper enclosure for it as the ambient temperature is a bit on the low side.<br><br />
''Currently its in a cardboard enclosure made from a very large cardboard Amazon box, with a thin plastic sheet curtain front. This is a fire risk, and replacement with a non-combustible enclosure (e.g. made from plaster wallboard) or flame-retardant enclosure should be a high priority. Unfortunately running without an enclosure isn't a good option due to the number of print failures I've had due to warping caused by drafts resulting in loss of bed adhesion.''<br><br />
<br><br />
'''''<nowiki>*</nowiki> I added a 50mm centrifugal part cooling fan, stuck onto the back of the extruder motor using 3M (clone) VHB tape, with a thin aluminum tapered duct aiming at the extruder nozzle. This fan is connected to the only software controlled fan port on the Anet3D controller - FAN1. (FAN2 is permanent 12V, used for controller board cooling.) The extruder cooling fan is now wired in parallel to the hot-end heater. ToDo: design and build an extruder fan run-on circuit so sit starts when the heater is first activated, then continues to run to keep the top of the heat-break cool till the hot-end is below 100°C (or maybe simply a retriggerable timer of several minutes).''''<br><br />
<br />
=== 13 Feb 2022 - Running out of program memory! ===<br />
I just managed to build Marlin v1.1.9 with UBL (unified bed levelling) to fit in a ATmega1284P (ANET 3D v1.5 board).<br><br />
<br><br />
Will I be using it? That's a hard *NO* because to get it to fit I had to disable just about everything else except thermal protection and minimal LCD menus. No SD support, no emergency parser, no cold extrusion prevention, no endstop interrupts, no G26 mesh validation print, no M503 and a host of other minor snips and vicious GCC size optimizations. I even rewrote the Arduino LiquidCrystal library with no 8 bit support to save another hundred bytes. Also it wont fit with *any* bootloader so the only option would be to use an AVR programmer and ISP. :(<br><br />
<br><br />
''Ian B: Seems that the ANET 3D board is seriously under-spec with that processor. It wouldn't have cost them much to fit a processor with bigger ROM.''<br> <br />
''Anyway, some say UBL is all it's cracked up to be. Just get your build plate physically level, as I'm sure you have.''<br><br />
(I suspect Ian B meant: "... UBL '''isn't''' all it's cracked up to be.")<br><br />
<br><br />
''Petr Cecil: Check the bigtreetech boards on the AliExpress I had one for about 12 quids in some sale, still running on it my ender 3''<br><br />
''They got much more memory''<br><br />
<br />
=== 16 Feb 2022 - More musings on bed levelling and program memory ===<br />
I was just looking at my options before building a Z probe. I've already got manual bed levelling with a 5x5 grid installed without disabling SD support or anything else nice to have, so I've just got to look at alternatives to full UBL. e.g. switch ''(from UBL)'' to AUTO_BED_LEVELING_BILINEAR with no other changes and it goes from needing 100% + 410 bytes more (than optiboot max user progmem) to only 62%, so I should be able to turn SD support back on + most of the nice stuff I pruned. Although a more capable controller would be *nice*, this *IS* only a £99 3D printer so its hard to justify spending for a good controller before I've even got all the mechanicals up to scratch.<br><br />
<br><br />
''My 3D printer build was then on hiatus for several months. I did do a couple of non-notable successful prints on its (questionably) manually leveled bed, and spent a fair bit of time teaching myself OpenSCAD.''<br />
<br />
=== 18 June 2022 - Upgrading the belt tensioners with ball bearings ===<br />
Previously:<br />
<blockquote><br />
* '''CAUTION: Belt tensioners' destroy themselves!'''<br />
The idiots at CTC used D shaft offcuts for the belt tensioner pully shafts and used the drive type pully for the idlers so the shaft turns with the pully. Running in a plastic hole with no bushing it acts as a D reamer and tries to chew its way back to the motor! A reasonable bodge fix is to flatten four M5 split washers ''(two for each tensioner)'', and wedge them in the recesses either side of the tensioner body, with the splits towards the tension screw. That's steel on steel, but if kept greased is better than steel D reamer on plastic! Long term it needs decent ball bearing tensioners.<br><br />
<br><br />
''[[#17 Jan 2022 - Running my own Marlin build and finding/fixing more mechanical defects|Ref: 17 Jan 2022 - finding/fixing more mechanical defects]]''<br />
</blockquote><br />
[[File:CTC Tensioner.png|thumb|Belt Tensioner]]<br />
Well I finally got and fitted MR85ZZ ball bearings to both belt tensioners on my CTC DiY I3 3D printer. The bearings are ludicrously tiny, 8mm OD, 5mm ID and only 2.5mm thick, which is only 1.5mm radially for both races and the balls between them, but that's what it takes to fit the bearing recess either side of CTC's 'factory' belt tensioner. Each bearing is held in its seat by a M3 screw next to the outer race, so they aren't going anywhere. I loctited the D shaft into the front X tensioner bearing so I shouldn't have any more failed prints due to it walking out of the idler pully.<br><br />
<br><br />
For anyone else contemplating the Zuhai CTC DiY I3, I couldn't find a STL (or any other model) of the tensioner anywhere, which as supplied is a wear part, and a rapidly wearing one at that, as the D shaft will chew the holes badly out of round in only a few hours printing unless you mod it so it isn't running edged steel on plastic, so (as usual) I modelled it in OpenSCAD, taking the dimensions as accurately as I could from the 'factory' tensioner. Get the tensioner model here: [[File:Tensioner4.zip]]<br><br />
<br />
=== 25 June 2022 - Testing a BLtouch probe ===<br />
<br />
I'm (slowly) working on adding auto bed levelling to my CTC DiY I3 3D printer.<br><br />
Here's an Arduino sketch to bench test a BLtouch/3Dtouch (or clone) levelling sensor, that lets you set probe states by single letter serial commands and reports the ZMIN output status, like this:<br><br />
<br />
*** BLtouch/3Dtouch probe tester ***<br />
D = Deploy<br />
T = Tswitch<br />
R = Retract<br />
S = Self test<br />
A = Alarm off<br />
? = read ZMIN<br />
The Arduino LED echoes the ZMIN state, ON=High / OFF=Low<br />
__________________________________________________________________<br />
________________#___________________________________#_#___________<br />
____________________###______####_______##########_________####___<br />
____####__________________________________<br />
ZMIN is Low (0.10V)<br />
____________________________######################################<br />
ZMIN is High (5.00V)<br />
#################_________________________________#_______________<br />
<br><br />
The sketch: [[File:BLtouch tester.zip]]<br />
<br />
=== 29 June 2022 - Mounting the BLtouch, and building Marlin to support it ===<br />
Slight progress on adding a BLtouch (clone) ABL sensor to my Zuhai CTC DiY I3, 3D printer. I've got the probe bracket printed and the BLtouch mounted on my printhead, with only 26mm Y offset, and nearly no X offset, without blocking access to the top of the throat in case of filament problems.<br><br />
<br><br />
''I drilled two 3mm holes just in from the front edge of the L bracket that holds the print head assembly to the X gantry carriage, in front of the mounting block that holds the hotend, to fix the bracket to with 2.5mm self-tappers from underneath into the printed probe bracket. My bracket was a little too low for the optimum probe height relative to the nozzle tip (above the tip by half the probe extension), so I ended up shimming it with a piece of wooden coffee stirrer. Once I touched it in with a black marker, you wouldn't know the shim is there, so although I fixed my OpenSCAD' bracket model, I'm going to be lazy/frugal and not re-printt it'<br> <br />
<br><br />
My printer uses an ANET3D v1.5 controller, so I've only got 128K FLASH on the ATmega1284P MCU to play with (half that on the usual ATmega2560 based boards), which has made building Marlin 1.1.9 small enough to fit with AUTO_BED_LEVELING_BILINEAR and BLTOUCH enabled quite a challenge.<br><br />
Even with aggressive GCC optimizations, (see links section below) it didn't quite fit until I disabled the boot screen. It was a choice between that and ditching Optiboot. :( <br />
Sketch uses 129932 bytes (99%) of program storage space. Maximum is 130048 bytes.<br />
Its a 'full fat' Marlin v1.1.9, with full menu, SD support and all the other nice to have goodies enabled., and I've still got 116 bytes left for any tweaks I want to add! 😁 <br><br />
<br><br />
''Petr Cecil: Just keep important features like thermal runaway protection on in marlin so you don't burn your home :))''<br />
<br />
''Yes, keeping thermal runaway protection was my highest priority. Without it, you are one loose screw away from a house fire! Many thanks to Petr for letting me use his crimper and JST connector parts to make up a JST XH-3 cable I badly needed for my BLtouch install. For anyone else needing JST XH (and duPont) crimping capability, here's what Petr recommends:'' <br />
https://www.amazon.co.uk/gp/product/B07VX6YGQ8/ ''and having used it, I would also recommend it.''<br><br />
<br />
=== 1 July 2022 - Wiring the BLtouch probe ===<br />
I've got most of the recabling done on my CTC DiY I3 for the BLtouch probe. I've spliced a three wire breakout cable for +5V Gnd and servo signal into my display ribbon cable, and re-done the loom to the printhead to add the BLtouch extension cables. All that's left to do is assemble the adapter board that Petr helped me with the JST cable for, mount and wire it, flash a BLtouch enabled Marlin build, and then I'll need to calibrate the Z offset.<br><br />
<br><br />
[[File:BLtouch combiner board.png|thumb]]<br />
... and here's the circuit I intend to use to combine use of the regular limit switch which is set up to inhibit Z movement approx half a mm below the bed surface (less than the flex in the gantry) so it cant 'dig for Australia' if for any reason the BLtouch wasn't deployed before homing.<br><br />
<br><br />
''I constructed the combiner board on Veroboard, laying it out using [https://veecad.com/ VeeCAD], from the schematic I drew up in [https://www.tinycad.net/ TinyCAD], mounted it to the printer and wired it up.''<br />
<br />
=== 5 July 2022 - Visualizing the bed levelling mesh ===<br />
Meanwhile, I've been futzing around with visualising 3D printer bed levelling meshes from Pronterface *without* pasting the M420 V mesh data into a website. Marlin comes with an OpenSCAD mesh visualiser called [https://github.com/MarlinFirmware/Marlin/blob/1.1.x/buildroot/share/scripts/MarlinMesh.scad MarlinMesh.scad], and it turns out that all you need to do to get external mesh data into that is to pass it in on the OpenSCAD command line as variables defined by -D override variables with file scope defined in the file. <br />
<br />
The prerequisites for using it are explained here, but if you've already got OpenSCAD installed and are using mesh bed levelling, you'll only need to skim this: https://3dwork.io/en/visualize-3d-mesh/<br />
<br />
To do this from Pronterface, with a hard coded mesh, as I hadn't figured out the M420 mesh parsing yet, put MarlinMesh.scad in the printrun directory and (on windows) in Pronterface send:<br />
<br />
!os.system('start /max "" "C:\Program Files\OpenSCAD\openscad.exe" MarlinMesh.scad -D $vpd=800 -D measured_z= <br />
[[-0.086,-0.045,-0.037,-0.046,-0.167,-0.292,-0.421],[+0.034,+0.038,-0.002,+0.017,-0.017,-0.121,-0.413], <br />
[+0.122,+0.098,+0.162,+0.034,-0.069,-0.234,-0.472],[+0.205,+0.196,+0.120,+0.071,-0.007,-0.149,-0.467], <br />
[+0.175,+0.174,+0.102,+0.010,-0.130,-0.313,-0.587],[+0.194,+0.189,+0.116,+0.034,-0.042,-0.170,-0.568], <br />
[+0.128,+0.089,+0.032,-0.033,-0.168,-0.373,-0.594]]')<br />
<br />
Note that this is currently Windows only, as the os.system() command string to launch OpenSCAD and return immediately:<br />
'start /max "" "C:\Program Files\OpenSCAD\openscad.exe" '<br />
will be very different under LINUX or OSX. The rest of the command line should be the same.<br />
<br />
Also I would strongly recommend editing the default mesh in MarlinMesh.scad (lines 24-30) to be a minimal 'null' mesh:<br />
measured_z=[[0,0],[0,0]]; //minimal mesh<br />
to make it obvious if your mesh data hasn't been passed in successfully.<br />
<br />
ToDo: Write a script to send G420 V to the printer and parse the returned mesh data into a string containing the mesh in the above OpenScad list of lists format, that can simply be appended to the os.system() command line after the -D measured_z=<br />
<br />
''Later that evening:''<br><br />
I've written and tested the Pronterface macro to launch MarlinMesh.scad from Pronterface with the printer's current MBL mesh from a M420 V report of the form:<br />
Bilinear Leveling Grid:<br />
0 1 2 3 4 5 6<br />
0 -0.086 -0.045 -0.037 -0.046 -0.167 -0.292 -0.421<br />
1 +0.034 +0.038 -0.002 +0.017 -0.017 -0.121 -0.413<br />
2 +0.122 +0.098 +0.162 +0.034 -0.069 -0.234 -0.472<br />
3 +0.205 +0.196 +0.120 +0.071 -0.007 -0.149 -0.467<br />
4 +0.175 +0.174 +0.102 +0.010 -0.130 -0.313 -0.587<br />
5 +0.194 +0.189 +0.116 +0.034 -0.042 -0.170 -0.568<br />
6 +0.128 +0.089 +0.032 -0.033 -0.168 -0.373 -0.594<br />
echo:Bed Leveling Off<br />
echo:Fade Height Off<br />
<br />
[[File:Bed mesh.png|thumb|My poor bed looks like a map of the Himalayas!]]<br />
So I've now got a Pronterface button that visualizes my bed live, without resorting to an online bed visualizer WWW site. 😁<br />
<br />
''Even with ABL enabled, its useful to let you see if your whole bed is out of whack' and could benefit from adjusting its levelling screws to reduce the range of Z offsets the ABL has to compensate for.'' <br />
<br />
It is currently Win x64 only, as the command line to launch OpenSCAD is OS specific. It shouldn't be hard to change that for Linux or OSX.<br />
<br />
To add it to your own Pronterface, first put MarlinMesh.scad in your Printrun folder, then paste the following into a new Pronterface macro:<br />
<pre><br />
!################# Bed Visulization macro #################<br />
!# Pronterface script to invoke OpenSCAD MarlinMesh with #<br />
!# the current MBL mesh returned by M420 V. #<br />
!# #<br />
!# (c) Ian.M 7/7/2022 #<br />
!# #<br />
!# "THE BEER-WARE LICENSE" (Revision 42): #<br />
!# "Ian.M" <https://t.me/Ian_M_2019> wrote this stuff. #<br />
!# As long as you retain this notice you can do whatever #<br />
!# you want with this stuff. If we meet some day, and #<br />
!# you think this stuff is worth it, you can buy me a #<br />
!# beer in return. Ian.M #<br />
!##########################################################<br />
!<br />
!import time<br />
!import os<br />
M420 V ; requst ML grid<br />
!time.sleep(1) # wait for it<br />
!idx=len(self.p.log)-1 # get last line in log buffer<br />
!idxf=None # error value <br />
!idxl=None<br />
!for x in range(idx,max(idx-20,0),-1): # iterate backwards <br />
! if self.p.log[x].find("Grid:")>8: # looking for 'Grid:', if found:<br />
! idxf=x+2 # set idxf to first (real) line of grid <br />
! break; # and exit loop<br />
! if self.p.log[x].find("echo:")==0: # looking for 'echo:', if found:<br />
! idxl=x-1 # set idxl to previous line till last line of grid is found<br />
!<br />
!#print("Debug: range "+str(idxf)+", "+str(idxl))<br />
!<br />
!if (idxf is None) or (idxl is None): # M420 failed<br />
! self.logError("Error: M420 failed")<br />
! return<br />
!if idxf>idxl: # M420 no grid<br />
! self.logError("Error: M420 did not return a grid")<br />
! return<br />
!<br />
!mesh="["<br />
!for x in range(idxf,idxl+1): # build list of OpenScad lists<br />
! mesh=mesh+"["+str(self.p.log[x])[3:].rstrip().replace(" ",",")+"]" # build comma separated list<br />
! if x<idxl:<br />
! mesh=mesh+"," # more to follow<br />
! else:<br />
! mesh=mesh+"]" # last one - end outer list<br />
!<br />
!# Build MMcmd for OpenSCAD installed in default location on 64 bit Windows.<br />
!# N.B use explicit 64 bit Program Files directory as Pronterface is a 32 bit application,<br />
!# so %ProgramFiles% returns %ProgramFiles(x86)%, which is the wrong folder.<br />
!MMcmd='start /max "" "%ProgramW6432%\\OpenSCAD\\OpenSCAD.exe" ' # change this OS dependent stuff!<br />
!MMparams="MarlinMesh.scad -D $vpd=800 -D measured_z=" # OpenSCAD command line parameters<br />
!# n.b. MarlinMesh.scad must be in printrun working directory<br />
!# -D defines an OpenSCAD constant for the session, overriding variables within the file. <br />
!<br />
!print("Invoking MarlinMesh.scad with this mesh.")<br />
!print("Exec: "+MMcmd+MMparams+mesh)<br />
!os.system(MMcmd+MMparams+mesh) #Execute it<br />
</pre><br />
<br />
''Edit: It turns out, that depending on your Pronterface version, you'll probably need to import '''os''' and '''time''' at the top of the macro. I've added them above.''<br />
<br />
=== 10 Sept 2022 - Z-screw wobble isolation ===<br />
Back in January I wrote:<br />
<blockquote><br />
The original rigid couplers between the Z stepper motors and the Z screws were unsatisfactory, as any misalignment directly pushed the gantry laterally resulting in prints with pronounced Z banding. I therefore bought some helical flexible couplers for coupling 5mm to 8mm shafts, and installed them with a 7mm ball bearing inside each to transfer the axial thrust loading from the Z screws direct to the motor shaft to minimize Z bounce. I had to shim the lead screws (which are ordinary M8 allthread) with aluminum cut from a drink can to get them concentric in the 8mm end of the coupler as their OD is slightly undersize.<br />
<br />
Although there was a notable improvement in print quality once I had carefully adjusted the coupler alignment, it wasn't a total cure as the lead screws are still shimmying enough to wobble the gentry at low Z heights. I need to decouple the drive nuts from the gantry, by flipping them the other way up and adding a thrust bearing that doesn't constrain them radially between them and the gantry. The nuts will also require anti-spin arms, and as the screws will no longer have any constraint above the couplers, they'll need top bearings.<br />
</blockquote><br />
<br />
At long last, I've completed the next stage of this, by laser cutting new top brackets and bearing retainers for 688ZZ ball bearings (8mm ID, 16mm OD, 5mm wide) from plywood, consisting of a redesigned bracket in 5mm ply, with a 16mm hole for the bearing which fits flush, surrounded by six tiny holes to fix retaining rings cut from 3mm ply above and below the bracket, each held by three tiny 2mm screws. I also laser cut the anti-spin arms for the Z-nuts from 5mm black Acrylic. All ply parts were spay painted matte black to match the rest of the printer frame. A Thursday evening well spent.<br />
<br />
I installed the parts and after some fiddling around managed to reduce the Z-screw runout, and got the screw centered well enough in the gantry end nut mounts not to touch and jerk. I still haven't got proper thrust bearings, and am making do with a stack of three M10 washers on the long end of each Z-nut, which have *NOT* been flipped as originally planned, as it looks like I'll need something other than the Z-screw to loosely constrain the thrust bearing. The washers are lightly greased so can slide over each other fairly readily<br />
<br />
After re-leveling (and some BLtouch calibration issues that were borking my first layer height), I finally managed to print a good test cube. Its got much less pronounced Z banding than before this upgrade. Hopefully adding ball thrust bearings will eliminate most of the residual banding. ToDo: design & fabricate cages for these bearings. The problem is a lack of space - I haven't got a lot of height between the top of the coupler and the bottom of the nut, and also, anything much larger than the 22mm OD of the nut flange would force me to move the part cooling fan and redesign its duct.<br />
<br />
''OpenSCAD design files and photos to follow''<br />
<br />
=== 06 January 2023 ===<br />
Another hiatus - I didn't need to do any 3D printing and was busy learning the RML mini-lathe.<br />
However I've made a small but significant improvement to the Z axis with nothing more than a few square cm of waxed paper! I took the backing paper off some double-sided tape, and wrapped one turn of the paper round the Z screw to make a spacer to fit inside the stack of washers. It sits over the lip on the end of the nut, inside the ID of the washer stack and helps the washer stack stay centered on the screw so none of them touch the screw, catch and jerk, but is so flimsy that the washers can still slide laterally with minimal extra force on the X gantry. A test cube showed much reduced Z banding vs the previous one from October.<br />
<br />
Its still not good enough as there is far too much runout at the bottom of the right-hand lead-screw which is shifting the X gantry support force to and fro enough to wobble it. Either I've got a bad coupler, its poorly assembled or there is a kink in the end of the screw where it was cut. Probably the best option will be to chuck the leadscrew in a soft collet in the lathe, get it running true, then turn the thread off the end of the leadscrew, shrink on a short bored out piece of steel rod, then turn that to 8.00 mm diameter, concentric to the screw, so I'm no longer trying to clamp on the threaded end.<br />
<br />
=== 16 December 2023 ===<br />
Some 3D printing of small parts this year, and several false starts with improving the lead screws. I spent quite a bit of lathe time doing test pieces with short lengths of M8 allthread. <br />
<br />
The soft collet idea was a non-starter as anything that grips on the thread tips gives poor concentricity. It turns out the answer is to wind a helix of soft iron or mild steel wire that fits the thread and grip on that so the grip is on the flanks of the thread. Also, shrink fitting was a bust - the precision and surface finish required to make it work for such small parts is right at the limit of RML's capabilities, and the tiny thermal mass gives only seconds to fit it and a fraction of a second to slide it home. The answer was loctite + machining to a push fit. 11 mm long, ~5.6 mm bore steel sleeves were made from 3/8" (9.5 mm) stock, and the thread turned down to fit for ~11 mm from the screw end. We don't have good enough bore measuring capability at RML so a test plug was turned to fit drilled bore to get the diameter to work to. Loctite was applied to both surfaces and the sleeve tapped on firmly. The OD was then turned to 8.00 mm and faced to 10 mm length, just cleaning up the screw end to get a true uniform end face, and the edge chamfered. <br />
<br />
I've got one leadscrew done, but time and machining mistakes were against me (I screwed up the 8.00 mm OD and had to turn the sleeve off and re-do it) so didn't get the second screw done. That's a job for tomorrow. <br />
<br />
Fitting and removing the screws now requires top corner plate removal. Run the gantry right up and hang it from the frame, then run the Z-nuts and their anti-rotation arms back down. Undo the coupler and take off the corner plate. The guide rod can be lifted and the anti-rotation arm swung clear, then the bottom end of the screw can be lifted off and slid down and forward till it can be slid out of the gantry end. Refitting is the reverse of removal.<br />
<br />
I've already got the left Z screw fitted, and the result is no obvious runout. Its highly dependent on the tightening sequence of the lower part of the helical coupler as excessive pressure with the split clamp causes the D shaft to go off center, so that should be lightly snugged up then the grubscrew tightened firmly on the flat. The grubscrew must be well aligned with the flat. Turn the other Z motor shaft to turn the one being assembled for access to the screws, as the coupler initially wont be tight enough to turn the motor.<br />
<br />
== - more to follow - ==<br />
<br />
== Some useful links ==<br />
* https://github.com/ralf-e/ANET-3D-Board-V1.0 - Schematic for an earlier version of the controller, near enough the same as the v1.5, and for the LCD2004 display/buttons board. Note that connector pinouts should be checked against the actual board before trusting them. e.g. I know the end stop connectors have pins 1 and 3 swapped vs the schematic.<br />
<br />
* http://lokspace.eu/anet-a8-wifi-mod/ - How to add printing over WiFi using an ESP-01 ESP8266 WiFi module and esp-link, by populating the Anet3D 'USB BLE' header + removing two zero ohm resistors. Level shifting is needed to get the 5V level ATmega TX pin down to 3.3V levels for the ESP8266 RX pin, hence the resistors on the carrier board. There's also no need for a USB UART adapter to flash the ESP8266, as the ANET main board has one of those. After dong the mainboard mod, simply take two short duPont F-F jumpers and link opposite corner pins of J8 the 'USB BLE' header, and use the mainboard's USB port. After flashing, remove the duPont wires, fit two jumper caps in the BLE position, and carry on with esp-link setup. Alternatively, use a Wemos D1 Mini clone which has all you need on-board except the level shifter, and its simple enough to solder two resistors for that. See my page [[WiFi 'tethered' Arduino robot]]<br />
<br />
* https://docs.arduino.cc/software/ide-v1/tutorials/PortableIDE - how to set up a portable install of the classic Arduino IDE which is strongly recommended for any existing Arduino user for building Marlin 1.1.x as you are likely to need to down-version the core and various libraries.<br />
<br />
* https://spiritdude.wordpress.com/2018/03/26/ctc-diy-prusa-i3-ctc-diy-i3-pro-b-most-affordable-3d-printer-2018/ - Another user's experiences with this printer.<br />
<br />
* https://ufj.ddns.net/blog/marlin/2019/01/07/reducing-marlin-binary-size.html - Turning on aggressive AVR GCC optimizations to reduce the size of the Marlin firmware, so it will fit in 128K program memory without having to prune too many desirable features.<br />
<br />
* https://all3dp.com/2/epic-3d-printing-fails-and-why-they-failed/ - some of the many ways things can go badly, ranging from potentially life-threatening, down through expensive and tedious, to mildly amusing.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_OpenSCAD_stuff&diff=17593Ian M's OpenSCAD stuff2023-11-25T09:53:12Z<p>IanM: /* Reading the BOSL2 documentation on Github restricted */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br><br />
<br><br />
I'm collecting my [https://openscad.org/ OpenSCAD] notes here. If you are looking for a tutorial for beginners you are in the wrong place as I doubt they'll ever be that well organized, but do check out my [[#Useful Links|'links']] section below.<br><br />
<br><br />
OpenSCAD is 3D CAD for people who prefer writing code to clicking and dragging stuff in a GUI. It uses its own declarative (functional) language to construct the object to render. In spite of its somewhat 'C'-like syntax, its very different 'under the hood' as variables are more like constants in other languages as they are immutable for the duration of their scope. i.e. '''a=a+1;''' is illegal. [https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/FAQ#Why_am_I_getting_an_error_when_writing_a_=_a_+_1? {ref}]<br><br />
<br><br />
Constraints are solely the responsibility of you the programmer to code and enforce. 'Vanilla' OpenSCAD without any libraries can be a PITA when constructing complex objects as you the programmer have to keep track of every dimension of every primitive shape to position them correctly relative to each other. However there are libraries that can hide much of the complexity - see below.<br />
<br />
== Customizer ==<br />
The [https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Customizer OpenSCAD customizer] is very powerful, but by default, every variable that you define at the top level in your file before any module definitions appears in it. Often, that's not what you want as many of them are probably being used as named constants to avoid sprinkling [https://en.wikipedia.org/wiki/Magic_number_(programming)#Unnamed_numerical_constants magic numbers] throughout your code.<br />
As the customizer only works on simple values, making the right hand side of the assignment an expression by appending +0, e.g.<br />
C=299792458 +0; // Speed of light (m/s)<br />
will exclude it from the customizer. Unfortunately enclosing the value in parentheses () is not sufficient.<br><br />
<br><br />
Alternatively, as noted in the documentation section 'supported variables', exclude all subsequent lines of the file from customization, by defining *any* module with a compound body (i.e. wrapped in braces {} ), even if null. e.g.<br />
module __Customizer_Limit__ () {} // end customizations<br />
<br />
If you *do* want to let a variable be customizable, it is generally worth explicitly specifying its limits and increment (which must be numeric - you cant use expressions or other variables) on the line defining it so the customizer displays a usable slider for it, e.g.<br />
lottoNum=13; //[1:1:49]<br />
and if its name isn't self explanatory, provide a comment describing it on the immediately preceding line.<br />
Grouping related variables into 'tabs' (which extend till the next named tab) using:<br />
/* [Tab Name] */<br />
can greatly help clarify which variables do what.<br />
<br />
== Variable scope and special variables ==<br />
Special variables are any variable with a name prefixed by $. Variables are immutable for the duration of their scope (either the file, or from the preceding { to the next } at the same level) and variables from enclosing scopes are inherited unless redefined. When you invoke a module or call a function, it does *NOT* inherit ordinary variables from its invoking/calling scope, but does from its definition's enclosing scope. Special variables are inherited from the invoking/calling scope so can be used to pass in data like parameters do. The *only* way to pass data back out of a scope is if that scope is the body of a function (from = to the terminating ;) as its return value. You cant 'leak' data from an inner to an outer scope via any type of variable. Running the sample code found at https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Other_Language_Features#Special_variables and carefully examining what it echoes to the console may help your understanding of OpenSCAD's scope rules.<br />
<br />
== So what's this $fa, $fs and $fn stuff? - smoothing arcs and circles ==<br />
Some OpenSCAD special variables are 'special'er than others because they control how OpenSCAD behaves. [https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Other_Language_Features#$fa,_$fs_and_$fn $fa, $fs and $fn] control how any constant radius curve or curved surface is rendered. That includes any sort of arc, and specifically the sphere and cylinder object primitives.<br />
<br />
OpenSCAD doesn't and cant output real arcs or curves when it renders an object as it outputs the surface of the compound object as a closed mesh of triangles, so it has to break up any arc into straight line segments. $fa, $fs and $fn control the resolution with which it does so. $fa is the minimum angle each segment will subtend, $fs is the minimum segment length, and $fn overrides the other two if non-zero and is the number of segments to use for a full circle, reduced pro-rata for arcs of less than 360°. See the link above for how they are used to calculate the segment length. The default value of $fa gives thirty segments in a full circle, but the default value of $fs is one, so at a bit under 10 units diameter, circular objects will start dropping segments, eventually becoming pentagonal when they get small enough.<br />
<br />
This is obviously undesirable when you are trying to construct a 3D printable part that needs bolt holes etc. You could override it by setting $fn but a high number of segments is computationally very costly - at least O(n²) for doubly curved surfaces - so setting $fn too high globally can lead to impracticably high render and preview times for complex models. Setting $fn locally is the best choice when a certain curved component or feature must be smoother than the rest. Otherwise, globally set $fs to an appropriate value for the print technology, 0.1 to 0.2 is 'in the ballpark' for most FDM print modelling, and set $fa to 360/N to choose the max segments N for larger circles. $fa still impacts rendering time, with smaller being worse, but at least you wont be attempting to render M3 bolt holes with μm precision!<br />
<br />
Another common use for setting $fn locally - usually within the parameters of circle() or cylinder() - is to generate regular polygons and regular prisms. e.g. <br />
<pre>cylinder(h=3.2, d=7/cos(30), $fn=6);</pre><br />
will generate a hexagonal prism the size of a M4 nut - 3.2mm thick, 7mm across flats. Note the division by the cosine of half the subtended angle of each face, to compute the diameter of the encompassing circle from the desired width across opposite faces.<br />
<br />
To get a feel for their effect try the following which renders a stack of disks of decreasing size, and adjust the customizer sliders, remembering that $fn must be zero for the others to be effective. If it isn't obvious, zoom in on the smaller disks at the top of the stack.<br />
<br />
<pre><br />
$fa=5;//[1:60]<br />
$fs=0.5;//[0.05:0.05:5]<br />
$fn=0;//[0:90]<br />
<br />
rs=[0.2,0.3,0.5,0.8,1,1.5,2,3,5,8,10,15,20];<br />
<br />
for(i=[1:len(rs)]){<br />
r=rs[i];<br />
translate([0,0,5*(len(rs)+1-i)])<br />
cylinder(h=3,r=r);<br />
}<br />
</pre><br />
<br />
== Scripting OpenSCAD ==<br />
You can run OpenSCAD from the command line and either silently render to a file or launch the GUI with command line options for preset customization or setting variables. See: [https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Using_OpenSCAD_in_a_command_line_environment Using OpenSCAD in a command line environment] in its user manual for details.<br />
<br />
Note that any variables set using the -D option have file scope and silently override any pre-existing file scope definitions for them in the file. They are persistent while the OpenSCAD GUI remains open. To clear the -D set variables, restart OpenSCAD!<br />
<br />
'''-D''' ''<varname>'''''='''''<value>''<br />
<br />
repeated for as many ''<varname>'' as you want to set, each with its own '''-D'''. If setting string variables you'll probably need to escape the quotes(") after the = and at the end of the string. See your OS specific documentation for command line / shell escape sequences for special characters.<br />
<br />
As an example, see: [[Ian M's £99 ZHUHAI CTC DiY I3 3D printer#5 July 2022 - Visualizing the bed levelling mesh|Visualizing the bed levelling mesh]] in my CTC DiY I3 printer blog page, for how I send the bed levelling mesh data from a Pronterface script (Python) to OpenSCAD for visualization.<br />
<br />
== What's BOSL2 and why should I use it? ==<br />
BOSL2 is the Belfry OpenScad Library, v2 (see link and description in [[#Recommended Libraries|'Recommended Libraries']] below). In this section I intend to show various cases where BOSL2 will make your life much easier. Lets start with:<br />
=== Threading ===<br />
[[File:NonBOSL screw.png|thumb|M10 male thread rendered with 'vanilla' OpenSCAD ]]<br />
Threaded objects in 'vanilla' OpenSCAD, without BOSL2 or any other threading library are a PITA!<br />
<pre><br />
//M10 thread parameters<br />
OD=10;<br />
P=1.5;<br />
L=15;<br />
TD=0.92;<br />
<br />
$fa=1; $fs=0.3; <br />
</pre><br />
<snipped 33 lines of support modules & functions + comments. See: [[File:NonBOSL screw.zip]]>[[File:NonBOSL screw section+profile.png|thumb|Cross-section and thread profile]]<br />
<pre> <br />
//Generate the thread cross section (XY plane) <br />
shape2=concat(arc2l(OD/2,ang=[0,22.5]),arc2l(OD/2,ang=[22.5,135],ri=-3.2*TD),arc2l(OD/2-TD,ang=[135,225]),arc2l(OD/2-TD,ang=[225,337.5],ri=3.2*TD),arc2l(OD/2,ang=[337.5,360])); <br />
<br />
linear_extrude(height = L, twist = -360*L/P)<br />
polygon(shape2); //Do the threaded rod<br />
</pre><br />
Note the complexity of building the cross section of the M10 thread, and that's before you even dig into what my arc2l() function does. It will probably take you an hour or two to match the thread form to the specification if you need to change it, and you have to look up the thread parameters manually for each size you want to be able to render<br />
<br />
With BOSL2 that reduces to:<br />
<pre><br />
include <BOSL2/std.scad><br />
include <BOSL2/screws.scad><br />
$fa=1; $fs=0.3; <br />
screw("M10", length=15);<br />
</pre><br />
and you can simply specify the screw by named size. Apart from coarse and fine ISO (metric) threads, [https://github.com/revarbat/BOSL2/wiki/screws.scad screws.scad] also handles UNC and UNF and a couple of other. If you need a Whitworth or BA thread you'll have to provide the profile and use the generic threading modules in [[https://github.com/revarbat/BOSL2/wiki/threading.scad threading.scad]]<br />
<br />
=== Pyramids! ===<br />
''Elsewhere 'M' wrote:''<br />
<blockquote><br />
I use ''%GUI_CAD%'', but struggle with it. Mostly because I use it infrequently and have to start over every time.<br />
<br />
Last time, I wanted a simple 3D trapezoid (flat top pyramid) and could not figure out all the dimensions. I have not gone beyond dropping in simple shapes and modifying them. It would be easy some times to start with a cube and then draw a slicing plane or line to complete a plane, but none of that is apparent how to do.<br />
</blockquote><br />
''(Nym and CAD software used anonymized for privacy) and I replied:''<br />
<br />
[[File:Truncpyramid.png|thumb]]In 'vanilla' OpenSCAD, a truncated square right pyramid is simply:<br />
<br />
<pre>rotate([0,0,45]) cylinder(h=10, d1=20*sqrt(2), d2=10*sqrt(2), $fn=4);</pre><br />
You may well ask what does a cylinder have to do with a pyramid?<br />
Well OpenSCAD allows you to use the cylinder object to make right regular prisms, by setting the number of vertices (and thus sides) with which it renders round objects. The $fn=4 thus gives four sides. You can also use the cylinder object for cones and frustums - you get a cone if you set r1 or d1 to the base size and r2 or d2 to 0 for a point at the top. Set r2 or d2 to a size smaller than the base and you get a frustum. The only remaining complexity is the '''*sqrt(2)''', and that's because when using $fn to make prisms, the diameter (or radius) gives the circumcircle, so we are effectively specifying the diagonal of the base and top squares, not their side length, so by Pythagoras, we need that correction factor. Finally as the circumcircle is divided into four equal sides starting with a vertex at angle 0, rotating it 45 deg about the Z axis brings the base and top sides parallel to the XY axes.<br />
<br />
If you are using OpenSCAD with the BOSL2 library, its a lot simpler:<br />
<pre>include <BOSL2/std.scad><br />
prismoid(size1=20, size2=10, h=10);</pre><br />
as prismoid specifically creates rectangular prisms and frustums.<br />
<br />
[[File:Bentpyramid.png|thumb]]It also easily allows you to stack them e.g. to model the [https://en.wikipedia.org/wiki/Bent_Pyramid Bent Pyramid of Sneferu] at a scale of 1:10000 (assuming the usual 3D printing convention of using mm as the unit):<br />
<pre>include <BOSL2/std.scad><br />
prismoid(size1=18.943, size2=12.358, h=4.704) attach(TOP) prismoid(size1=12.358, size2=0, h=5.767);</pre><br />
I find it a lot easier to explore OpenSCAD, simply keeping the 'vanilla' and BOSL2 cheatsheats bookmarked in my browser, than it is to explore the myriad modes of ''%GUI_CAD%'' to find a reasonable method to do anything semi-fancy.<br />
<br />
=== Bezier Curves ===<br />
[[File:Bezier.png|thumb|The Excel97 GUI Bezier Editor]]<br />
BOSL2 has various functions and modules to aid generating and using [https://en.wikipedia.org/wiki/B%C3%A9zier_curve#:~:text=A%20B%C3%A9zier%20curve%20(%2F%CB%88b,by%20means%20of%20a%20formula. Bezier curves]. However it lacks easy click & drag customization of the curve as the OpenSCAD customizer doesn't have any 'click in the plot' coordinate setting functionality, or even X and Y sliders for points, and also borks lists of lists, so I wrote an Excel 97 spreadsheet to generate OpenSCAD Bezier points lists for three, four and five control point Bezier curves.<br />
<br />
It should work in Excel 97 - 2003. Excel 2007 onwards lack the capability to drag plot points<sup>*</sup>. <br />
<br />
''* It may be possible to get point dragging (or at least GUI manipulation) back with the (depreciated) [https://web.archive.org/web/20170904131448/https://blogs.office.com/en-us/2009/11/02/excel-add-in-for-manipulating-points-on-charts-mpoc/ MPOC addin] (which you have to get from a 3rd party site as Microsoft have killed it and all related pages - try the Internet Archive [http://download.microsoft.com/download/9/D/D/9DDA9AFB-A349-41F5-9757-70D4DBA9238D/MPOC.zip [here<nowiki>]</nowiki>] to download) but as I don't have Excel 2007 or higher, that's untested and YMMV!''<br />
<br />
[[File:Bezier.xls]]<br />
<br />
==== A nose cap for the RML Dremel ====<br />
The original went walkabout many moons ago and genuine ones are ridiculously expensive so we needed to 3D print one. <br />
[[File:DremelCapProfile.png|thumb|A Bezier curve for the outer profile of the cap, to generate a solid of revolution]] <br />
[[File:DremelCap.png|thumb|A render of the complete cap]]<br />
Note the use of multiplication by a scaling matrix:<br />
<pre>bezier_points*[[Xscale/100,0],[0,Yscale/100]]</pre><br />
to scale the fixed size curve to the parametric cap diameter and length.<br />
<br />
The complete code:<br />
<br />
<pre>include <BOSL2/std.scad><br />
include <BOSL2/beziers.scad><br />
include <BOSL2/threading.scad><br />
<br />
//Dremel:<br />
//thread len 8.8mm plain 2.5mm total 11.3mm#<br />
//collet nut od 10.6mm<br />
<br />
/* [Thread (US inch)] */<br />
D=0.75; <br />
TPI=12; <br />
<br />
/*[Other Parameters (Metric)][*/<br />
// Diameter of Dremel body at nose<br />
OD=22.6;<br />
// Length of noze<br />
tl=11.3;<br />
// unthreaded length at base of nose<br />
ul=2;<br />
// Thickness (additional length) of cap<br />
cl=2;<br />
// Hole dia. for spindle<br />
id=12;<br />
/*[Printer calibration]*/<br />
//See BOSL2 wiki: Constants.scad: $slop: Calibration<br />
$slop=0.3;//[0:0.05:0.35]<br />
/*[Arc resolution]*/<br />
$fa=5;<br />
$fs=0.1;<br />
<br />
module __Customizer_Limit__ () {} // end customizer<br />
$dd=0+1E-3;<br />
bez=[[100,0],[102.62,74.95],[85,85],[159.96,102.1],[100,100]];<br />
<br />
*debug_bezier(bez, N=len(bez)-1); // show only with ! or exclude with *<br />
<br />
pl=close_path(concat([[0,0]],bezier_curve(bez, 32),[[0,100]]));<br />
<br />
//render() // only needed for graphics cards with broken OpenGL<br />
diff("x"){<br />
// "x" cuts<br />
tag("x") threaded_rod(d=D*INCH, l=tl+2*$dd, pitch=INCH/TPI, internal=true){<br />
attach(BOTTOM,BOTTOM,norot=true)<br />
cyl(d=D*INCH+4*$slop,h=ul+INCH/(2*TPI),chamfer2=INCH/(2*TPI)) ;<br />
attach(TOP,BOTTOM,overlap=$dd)<br />
cyl(d=id+4*$slop,h=cl+$dd)<br />
attach(TOP,BOTTOM) cyl(r=OD,h=10)<br />
;<br />
attach(BOTTOM,TOP) cyl(r=OD,h=10);<br />
} //end "x" cuts<br />
down(tl/2) rotate_sweep(pl*[[OD/200,0],[0,(tl+cl)/100]]); // Plain<br />
//down(tl/2) textured_revolution(pl*[[OD/200,0],[0,(tl+cl)/100]], "ribs",[2,0.2],tscale=0.6); // Ridged for grip<br />
}</pre><br />
<br />
''I printed it on my CTC DiY I3 at home, and it fitted my non-Dremel rotary tool nicely, so I knew the thread's OK. The next Tuesday I fitted it to the RML Dremel, and it turned out to be a very nice snug fit, with a barely noticeable ridge at the transition between cap and body.''<br />
<br />
=== TLDR: Use BOSL2! ===<br />
<under construction><br />
<br />
== BOSL2 Issues ==<br />
<br />
=== The documentation doesn't match! ===<br />
Sometimes you find that when you paste (complete) example code from the BOSL2 wiki into OpenSCAD, it doesn't work and you get a '''WARNING: Ignoring unknown function''' ... or '''WARNING: Ignoring unknown module''' ... error. <br />
<br />
Looking in your local copy of the corresponding BOSL2 library source file, you find the function or module has a different name or is simply missing. This usually doesn't mean the wiki is wrong, as its a big hint that your BOSL2 is out of date and you need to download it again (as the documentation is usually updated to reflect the current state of development). Archive a copy of the previous version in case the new version breaks any of your older OpenSCAD BOSL2 projects.<br />
<br />
There is a BOSL2 version number, currently<sup>*</sup> 2.0.652, which you can interrogate but it isn't much use for checking code compatibility as it hasn't been incremented since last year, and usually isn't 'bumped' for changes that break backwards compatibility!<br />
<br />
''* as of August 2022''<br />
<br />
=== Reading the BOSL2 documentation on Github restricted ===<br />
When browsing the BOSL2 wiki, while not logged in to Github, you may get an error page:<br />
: Access to this site has been restricted<br />
It can be triggered by only following a few links, and is persistent, blocking all access to any Github pages (including login). It is believed to be related to the number of large images on some of the BOSL2 wiki pages resulting in hitting a bandwidth threshold when skipping through pages. It may clear after ten minutes inactivity. Alternatively try clearing all Github cookies and restart your browser. If you get it, you will need to log in to Github to prevent it recurring, as persisting unauthenticated may result in an IP ban.<br />
<br />
== Laser Cutting with OpenSCAD ==<br />
Has its own page: [[OpenSCAD to Laser Cutter]]<br />
<br />
Also see: B. M. Sleight's Lasercut library (link below)<br />
<br />
== Recommended Libraries ==<br />
https://github.com/BelfrySCAD/BOSL2 - The Belfry OpenScad Library, v2. A massive 'Swiss Army Knife' library that handles nearly everything you'll need to construct complex objects. e.g. attaching child objects to anchor points on a parent without having to worry about their absolute position, rounding/chamfering edges and corners, screw threading and more other stuff than you can shake a stick at. My #1 recommendation for *any* OpenSCAD user.<br><br />
<br><br />
https://github.com/bmsleight/lasercut - B. M. Sleight's Lasercut library handles extracting 2D geometry from components of a 3D model and 'plating' the result for laser cutting. See full description in the [[OpenSCAD to Laser Cutter#Recommended Libraries for laser cutting|Libraries section]] of my OpenSCAD to Laser Cutter page<br />
<br />
== Useful Links ==<br />
https://mastering-openscad.eu/ - "Mastering OpenSCAD: within 10 projects" by Jochen Kerdels, ISBN: 978 3753 458 588<br />
<blockquote>The book Mastering OpenSCAD introduces you to all important concepts and functionalities of OpenSCAD. The book guides you through 10 selected projects step by step, each project focusing on a limited set of functions and concepts. After these 10 projects, you will know all practically relevant features of OpenSCAD. For the sake of completeness, a final chapter briefly presents the functions that were not addressed in any of the projects.</blockquote><br />
Read online for free [https://mastering-openscad.eu/buch/introduction/ [here<nowiki>]</nowiki>] or buy the [https://www.amazon.co.uk/dp/3753458589 paperback from Amazon].<br />
<br />
<br />
https://www.reddit.com/r/openscad/ - Reddit: r/OpenSCAD - a fairly popular<sup>*</sup> unofficial forum for OpenSCAD discussions. The [https://forum.openscad.org/ official forum] originally was integrated with the OpenSCAD mailing list, but Nabble broke that so its mostly inactive.<br />
<br />
''* 29 threads in the last month, when I wrote this.''</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_OpenSCAD_stuff&diff=17592Ian M's OpenSCAD stuff2023-11-25T09:49:07Z<p>IanM: /* BOSL2 Issues */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br><br />
<br><br />
I'm collecting my [https://openscad.org/ OpenSCAD] notes here. If you are looking for a tutorial for beginners you are in the wrong place as I doubt they'll ever be that well organized, but do check out my [[#Useful Links|'links']] section below.<br><br />
<br><br />
OpenSCAD is 3D CAD for people who prefer writing code to clicking and dragging stuff in a GUI. It uses its own declarative (functional) language to construct the object to render. In spite of its somewhat 'C'-like syntax, its very different 'under the hood' as variables are more like constants in other languages as they are immutable for the duration of their scope. i.e. '''a=a+1;''' is illegal. [https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/FAQ#Why_am_I_getting_an_error_when_writing_a_=_a_+_1? {ref}]<br><br />
<br><br />
Constraints are solely the responsibility of you the programmer to code and enforce. 'Vanilla' OpenSCAD without any libraries can be a PITA when constructing complex objects as you the programmer have to keep track of every dimension of every primitive shape to position them correctly relative to each other. However there are libraries that can hide much of the complexity - see below.<br />
<br />
== Customizer ==<br />
The [https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Customizer OpenSCAD customizer] is very powerful, but by default, every variable that you define at the top level in your file before any module definitions appears in it. Often, that's not what you want as many of them are probably being used as named constants to avoid sprinkling [https://en.wikipedia.org/wiki/Magic_number_(programming)#Unnamed_numerical_constants magic numbers] throughout your code.<br />
As the customizer only works on simple values, making the right hand side of the assignment an expression by appending +0, e.g.<br />
C=299792458 +0; // Speed of light (m/s)<br />
will exclude it from the customizer. Unfortunately enclosing the value in parentheses () is not sufficient.<br><br />
<br><br />
Alternatively, as noted in the documentation section 'supported variables', exclude all subsequent lines of the file from customization, by defining *any* module with a compound body (i.e. wrapped in braces {} ), even if null. e.g.<br />
module __Customizer_Limit__ () {} // end customizations<br />
<br />
If you *do* want to let a variable be customizable, it is generally worth explicitly specifying its limits and increment (which must be numeric - you cant use expressions or other variables) on the line defining it so the customizer displays a usable slider for it, e.g.<br />
lottoNum=13; //[1:1:49]<br />
and if its name isn't self explanatory, provide a comment describing it on the immediately preceding line.<br />
Grouping related variables into 'tabs' (which extend till the next named tab) using:<br />
/* [Tab Name] */<br />
can greatly help clarify which variables do what.<br />
<br />
== Variable scope and special variables ==<br />
Special variables are any variable with a name prefixed by $. Variables are immutable for the duration of their scope (either the file, or from the preceding { to the next } at the same level) and variables from enclosing scopes are inherited unless redefined. When you invoke a module or call a function, it does *NOT* inherit ordinary variables from its invoking/calling scope, but does from its definition's enclosing scope. Special variables are inherited from the invoking/calling scope so can be used to pass in data like parameters do. The *only* way to pass data back out of a scope is if that scope is the body of a function (from = to the terminating ;) as its return value. You cant 'leak' data from an inner to an outer scope via any type of variable. Running the sample code found at https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Other_Language_Features#Special_variables and carefully examining what it echoes to the console may help your understanding of OpenSCAD's scope rules.<br />
<br />
== So what's this $fa, $fs and $fn stuff? - smoothing arcs and circles ==<br />
Some OpenSCAD special variables are 'special'er than others because they control how OpenSCAD behaves. [https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Other_Language_Features#$fa,_$fs_and_$fn $fa, $fs and $fn] control how any constant radius curve or curved surface is rendered. That includes any sort of arc, and specifically the sphere and cylinder object primitives.<br />
<br />
OpenSCAD doesn't and cant output real arcs or curves when it renders an object as it outputs the surface of the compound object as a closed mesh of triangles, so it has to break up any arc into straight line segments. $fa, $fs and $fn control the resolution with which it does so. $fa is the minimum angle each segment will subtend, $fs is the minimum segment length, and $fn overrides the other two if non-zero and is the number of segments to use for a full circle, reduced pro-rata for arcs of less than 360°. See the link above for how they are used to calculate the segment length. The default value of $fa gives thirty segments in a full circle, but the default value of $fs is one, so at a bit under 10 units diameter, circular objects will start dropping segments, eventually becoming pentagonal when they get small enough.<br />
<br />
This is obviously undesirable when you are trying to construct a 3D printable part that needs bolt holes etc. You could override it by setting $fn but a high number of segments is computationally very costly - at least O(n²) for doubly curved surfaces - so setting $fn too high globally can lead to impracticably high render and preview times for complex models. Setting $fn locally is the best choice when a certain curved component or feature must be smoother than the rest. Otherwise, globally set $fs to an appropriate value for the print technology, 0.1 to 0.2 is 'in the ballpark' for most FDM print modelling, and set $fa to 360/N to choose the max segments N for larger circles. $fa still impacts rendering time, with smaller being worse, but at least you wont be attempting to render M3 bolt holes with μm precision!<br />
<br />
Another common use for setting $fn locally - usually within the parameters of circle() or cylinder() - is to generate regular polygons and regular prisms. e.g. <br />
<pre>cylinder(h=3.2, d=7/cos(30), $fn=6);</pre><br />
will generate a hexagonal prism the size of a M4 nut - 3.2mm thick, 7mm across flats. Note the division by the cosine of half the subtended angle of each face, to compute the diameter of the encompassing circle from the desired width across opposite faces.<br />
<br />
To get a feel for their effect try the following which renders a stack of disks of decreasing size, and adjust the customizer sliders, remembering that $fn must be zero for the others to be effective. If it isn't obvious, zoom in on the smaller disks at the top of the stack.<br />
<br />
<pre><br />
$fa=5;//[1:60]<br />
$fs=0.5;//[0.05:0.05:5]<br />
$fn=0;//[0:90]<br />
<br />
rs=[0.2,0.3,0.5,0.8,1,1.5,2,3,5,8,10,15,20];<br />
<br />
for(i=[1:len(rs)]){<br />
r=rs[i];<br />
translate([0,0,5*(len(rs)+1-i)])<br />
cylinder(h=3,r=r);<br />
}<br />
</pre><br />
<br />
== Scripting OpenSCAD ==<br />
You can run OpenSCAD from the command line and either silently render to a file or launch the GUI with command line options for preset customization or setting variables. See: [https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Using_OpenSCAD_in_a_command_line_environment Using OpenSCAD in a command line environment] in its user manual for details.<br />
<br />
Note that any variables set using the -D option have file scope and silently override any pre-existing file scope definitions for them in the file. They are persistent while the OpenSCAD GUI remains open. To clear the -D set variables, restart OpenSCAD!<br />
<br />
'''-D''' ''<varname>'''''='''''<value>''<br />
<br />
repeated for as many ''<varname>'' as you want to set, each with its own '''-D'''. If setting string variables you'll probably need to escape the quotes(") after the = and at the end of the string. See your OS specific documentation for command line / shell escape sequences for special characters.<br />
<br />
As an example, see: [[Ian M's £99 ZHUHAI CTC DiY I3 3D printer#5 July 2022 - Visualizing the bed levelling mesh|Visualizing the bed levelling mesh]] in my CTC DiY I3 printer blog page, for how I send the bed levelling mesh data from a Pronterface script (Python) to OpenSCAD for visualization.<br />
<br />
== What's BOSL2 and why should I use it? ==<br />
BOSL2 is the Belfry OpenScad Library, v2 (see link and description in [[#Recommended Libraries|'Recommended Libraries']] below). In this section I intend to show various cases where BOSL2 will make your life much easier. Lets start with:<br />
=== Threading ===<br />
[[File:NonBOSL screw.png|thumb|M10 male thread rendered with 'vanilla' OpenSCAD ]]<br />
Threaded objects in 'vanilla' OpenSCAD, without BOSL2 or any other threading library are a PITA!<br />
<pre><br />
//M10 thread parameters<br />
OD=10;<br />
P=1.5;<br />
L=15;<br />
TD=0.92;<br />
<br />
$fa=1; $fs=0.3; <br />
</pre><br />
<snipped 33 lines of support modules & functions + comments. See: [[File:NonBOSL screw.zip]]>[[File:NonBOSL screw section+profile.png|thumb|Cross-section and thread profile]]<br />
<pre> <br />
//Generate the thread cross section (XY plane) <br />
shape2=concat(arc2l(OD/2,ang=[0,22.5]),arc2l(OD/2,ang=[22.5,135],ri=-3.2*TD),arc2l(OD/2-TD,ang=[135,225]),arc2l(OD/2-TD,ang=[225,337.5],ri=3.2*TD),arc2l(OD/2,ang=[337.5,360])); <br />
<br />
linear_extrude(height = L, twist = -360*L/P)<br />
polygon(shape2); //Do the threaded rod<br />
</pre><br />
Note the complexity of building the cross section of the M10 thread, and that's before you even dig into what my arc2l() function does. It will probably take you an hour or two to match the thread form to the specification if you need to change it, and you have to look up the thread parameters manually for each size you want to be able to render<br />
<br />
With BOSL2 that reduces to:<br />
<pre><br />
include <BOSL2/std.scad><br />
include <BOSL2/screws.scad><br />
$fa=1; $fs=0.3; <br />
screw("M10", length=15);<br />
</pre><br />
and you can simply specify the screw by named size. Apart from coarse and fine ISO (metric) threads, [https://github.com/revarbat/BOSL2/wiki/screws.scad screws.scad] also handles UNC and UNF and a couple of other. If you need a Whitworth or BA thread you'll have to provide the profile and use the generic threading modules in [[https://github.com/revarbat/BOSL2/wiki/threading.scad threading.scad]]<br />
<br />
=== Pyramids! ===<br />
''Elsewhere 'M' wrote:''<br />
<blockquote><br />
I use ''%GUI_CAD%'', but struggle with it. Mostly because I use it infrequently and have to start over every time.<br />
<br />
Last time, I wanted a simple 3D trapezoid (flat top pyramid) and could not figure out all the dimensions. I have not gone beyond dropping in simple shapes and modifying them. It would be easy some times to start with a cube and then draw a slicing plane or line to complete a plane, but none of that is apparent how to do.<br />
</blockquote><br />
''(Nym and CAD software used anonymized for privacy) and I replied:''<br />
<br />
[[File:Truncpyramid.png|thumb]]In 'vanilla' OpenSCAD, a truncated square right pyramid is simply:<br />
<br />
<pre>rotate([0,0,45]) cylinder(h=10, d1=20*sqrt(2), d2=10*sqrt(2), $fn=4);</pre><br />
You may well ask what does a cylinder have to do with a pyramid?<br />
Well OpenSCAD allows you to use the cylinder object to make right regular prisms, by setting the number of vertices (and thus sides) with which it renders round objects. The $fn=4 thus gives four sides. You can also use the cylinder object for cones and frustums - you get a cone if you set r1 or d1 to the base size and r2 or d2 to 0 for a point at the top. Set r2 or d2 to a size smaller than the base and you get a frustum. The only remaining complexity is the '''*sqrt(2)''', and that's because when using $fn to make prisms, the diameter (or radius) gives the circumcircle, so we are effectively specifying the diagonal of the base and top squares, not their side length, so by Pythagoras, we need that correction factor. Finally as the circumcircle is divided into four equal sides starting with a vertex at angle 0, rotating it 45 deg about the Z axis brings the base and top sides parallel to the XY axes.<br />
<br />
If you are using OpenSCAD with the BOSL2 library, its a lot simpler:<br />
<pre>include <BOSL2/std.scad><br />
prismoid(size1=20, size2=10, h=10);</pre><br />
as prismoid specifically creates rectangular prisms and frustums.<br />
<br />
[[File:Bentpyramid.png|thumb]]It also easily allows you to stack them e.g. to model the [https://en.wikipedia.org/wiki/Bent_Pyramid Bent Pyramid of Sneferu] at a scale of 1:10000 (assuming the usual 3D printing convention of using mm as the unit):<br />
<pre>include <BOSL2/std.scad><br />
prismoid(size1=18.943, size2=12.358, h=4.704) attach(TOP) prismoid(size1=12.358, size2=0, h=5.767);</pre><br />
I find it a lot easier to explore OpenSCAD, simply keeping the 'vanilla' and BOSL2 cheatsheats bookmarked in my browser, than it is to explore the myriad modes of ''%GUI_CAD%'' to find a reasonable method to do anything semi-fancy.<br />
<br />
=== Bezier Curves ===<br />
[[File:Bezier.png|thumb|The Excel97 GUI Bezier Editor]]<br />
BOSL2 has various functions and modules to aid generating and using [https://en.wikipedia.org/wiki/B%C3%A9zier_curve#:~:text=A%20B%C3%A9zier%20curve%20(%2F%CB%88b,by%20means%20of%20a%20formula. Bezier curves]. However it lacks easy click & drag customization of the curve as the OpenSCAD customizer doesn't have any 'click in the plot' coordinate setting functionality, or even X and Y sliders for points, and also borks lists of lists, so I wrote an Excel 97 spreadsheet to generate OpenSCAD Bezier points lists for three, four and five control point Bezier curves.<br />
<br />
It should work in Excel 97 - 2003. Excel 2007 onwards lack the capability to drag plot points<sup>*</sup>. <br />
<br />
''* It may be possible to get point dragging (or at least GUI manipulation) back with the (depreciated) [https://web.archive.org/web/20170904131448/https://blogs.office.com/en-us/2009/11/02/excel-add-in-for-manipulating-points-on-charts-mpoc/ MPOC addin] (which you have to get from a 3rd party site as Microsoft have killed it and all related pages - try the Internet Archive [http://download.microsoft.com/download/9/D/D/9DDA9AFB-A349-41F5-9757-70D4DBA9238D/MPOC.zip [here<nowiki>]</nowiki>] to download) but as I don't have Excel 2007 or higher, that's untested and YMMV!''<br />
<br />
[[File:Bezier.xls]]<br />
<br />
==== A nose cap for the RML Dremel ====<br />
The original went walkabout many moons ago and genuine ones are ridiculously expensive so we needed to 3D print one. <br />
[[File:DremelCapProfile.png|thumb|A Bezier curve for the outer profile of the cap, to generate a solid of revolution]] <br />
[[File:DremelCap.png|thumb|A render of the complete cap]]<br />
Note the use of multiplication by a scaling matrix:<br />
<pre>bezier_points*[[Xscale/100,0],[0,Yscale/100]]</pre><br />
to scale the fixed size curve to the parametric cap diameter and length.<br />
<br />
The complete code:<br />
<br />
<pre>include <BOSL2/std.scad><br />
include <BOSL2/beziers.scad><br />
include <BOSL2/threading.scad><br />
<br />
//Dremel:<br />
//thread len 8.8mm plain 2.5mm total 11.3mm#<br />
//collet nut od 10.6mm<br />
<br />
/* [Thread (US inch)] */<br />
D=0.75; <br />
TPI=12; <br />
<br />
/*[Other Parameters (Metric)][*/<br />
// Diameter of Dremel body at nose<br />
OD=22.6;<br />
// Length of noze<br />
tl=11.3;<br />
// unthreaded length at base of nose<br />
ul=2;<br />
// Thickness (additional length) of cap<br />
cl=2;<br />
// Hole dia. for spindle<br />
id=12;<br />
/*[Printer calibration]*/<br />
//See BOSL2 wiki: Constants.scad: $slop: Calibration<br />
$slop=0.3;//[0:0.05:0.35]<br />
/*[Arc resolution]*/<br />
$fa=5;<br />
$fs=0.1;<br />
<br />
module __Customizer_Limit__ () {} // end customizer<br />
$dd=0+1E-3;<br />
bez=[[100,0],[102.62,74.95],[85,85],[159.96,102.1],[100,100]];<br />
<br />
*debug_bezier(bez, N=len(bez)-1); // show only with ! or exclude with *<br />
<br />
pl=close_path(concat([[0,0]],bezier_curve(bez, 32),[[0,100]]));<br />
<br />
//render() // only needed for graphics cards with broken OpenGL<br />
diff("x"){<br />
// "x" cuts<br />
tag("x") threaded_rod(d=D*INCH, l=tl+2*$dd, pitch=INCH/TPI, internal=true){<br />
attach(BOTTOM,BOTTOM,norot=true)<br />
cyl(d=D*INCH+4*$slop,h=ul+INCH/(2*TPI),chamfer2=INCH/(2*TPI)) ;<br />
attach(TOP,BOTTOM,overlap=$dd)<br />
cyl(d=id+4*$slop,h=cl+$dd)<br />
attach(TOP,BOTTOM) cyl(r=OD,h=10)<br />
;<br />
attach(BOTTOM,TOP) cyl(r=OD,h=10);<br />
} //end "x" cuts<br />
down(tl/2) rotate_sweep(pl*[[OD/200,0],[0,(tl+cl)/100]]); // Plain<br />
//down(tl/2) textured_revolution(pl*[[OD/200,0],[0,(tl+cl)/100]], "ribs",[2,0.2],tscale=0.6); // Ridged for grip<br />
}</pre><br />
<br />
''I printed it on my CTC DiY I3 at home, and it fitted my non-Dremel rotary tool nicely, so I knew the thread's OK. The next Tuesday I fitted it to the RML Dremel, and it turned out to be a very nice snug fit, with a barely noticeable ridge at the transition between cap and body.''<br />
<br />
=== TLDR: Use BOSL2! ===<br />
<under construction><br />
<br />
== BOSL2 Issues ==<br />
<br />
=== The documentation doesn't match! ===<br />
Sometimes you find that when you paste (complete) example code from the BOSL2 wiki into OpenSCAD, it doesn't work and you get a '''WARNING: Ignoring unknown function''' ... or '''WARNING: Ignoring unknown module''' ... error. <br />
<br />
Looking in your local copy of the corresponding BOSL2 library source file, you find the function or module has a different name or is simply missing. This usually doesn't mean the wiki is wrong, as its a big hint that your BOSL2 is out of date and you need to download it again (as the documentation is usually updated to reflect the current state of development). Archive a copy of the previous version in case the new version breaks any of your older OpenSCAD BOSL2 projects.<br />
<br />
There is a BOSL2 version number, currently<sup>*</sup> 2.0.652, which you can interrogate but it isn't much use for checking code compatibility as it hasn't been incremented since last year, and usually isn't 'bumped' for changes that break backwards compatibility!<br />
<br />
''* as of August 2022''<br />
<br />
=== Reading the BOSL2 documentation on Github restricted ===<br />
If not logged in to Github, you may get an error page:<br />
: Access to this site has been restricted<br />
while browsing the documentation. It can be triggered by only following a few links, and is persistent, blocking all access to any Github pages (including login). It may clear after ten minutes inactivity. Alternatively try clearing all Github cookies and restart your browser. If you get it, you will need to log in to Github to prevent it recurring, as persisting unauthenticated may result in an IP ban.<br />
<br />
== Laser Cutting with OpenSCAD ==<br />
Has its own page: [[OpenSCAD to Laser Cutter]]<br />
<br />
Also see: B. M. Sleight's Lasercut library (link below)<br />
<br />
== Recommended Libraries ==<br />
https://github.com/BelfrySCAD/BOSL2 - The Belfry OpenScad Library, v2. A massive 'Swiss Army Knife' library that handles nearly everything you'll need to construct complex objects. e.g. attaching child objects to anchor points on a parent without having to worry about their absolute position, rounding/chamfering edges and corners, screw threading and more other stuff than you can shake a stick at. My #1 recommendation for *any* OpenSCAD user.<br><br />
<br><br />
https://github.com/bmsleight/lasercut - B. M. Sleight's Lasercut library handles extracting 2D geometry from components of a 3D model and 'plating' the result for laser cutting. See full description in the [[OpenSCAD to Laser Cutter#Recommended Libraries for laser cutting|Libraries section]] of my OpenSCAD to Laser Cutter page<br />
<br />
== Useful Links ==<br />
https://mastering-openscad.eu/ - "Mastering OpenSCAD: within 10 projects" by Jochen Kerdels, ISBN: 978 3753 458 588<br />
<blockquote>The book Mastering OpenSCAD introduces you to all important concepts and functionalities of OpenSCAD. The book guides you through 10 selected projects step by step, each project focusing on a limited set of functions and concepts. After these 10 projects, you will know all practically relevant features of OpenSCAD. For the sake of completeness, a final chapter briefly presents the functions that were not addressed in any of the projects.</blockquote><br />
Read online for free [https://mastering-openscad.eu/buch/introduction/ [here<nowiki>]</nowiki>] or buy the [https://www.amazon.co.uk/dp/3753458589 paperback from Amazon].<br />
<br />
<br />
https://www.reddit.com/r/openscad/ - Reddit: r/OpenSCAD - a fairly popular<sup>*</sup> unofficial forum for OpenSCAD discussions. The [https://forum.openscad.org/ official forum] originally was integrated with the OpenSCAD mailing list, but Nabble broke that so its mostly inactive.<br />
<br />
''* 29 threads in the last month, when I wrote this.''</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_Lathe_Notes&diff=17591Ian M's Lathe Notes2023-11-25T09:20:09Z<p>IanM: /* Issues and Annoyances */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br />
<br />
''Currently these notes are semi-organized and non-authoritative. As I become more experienced with the RML CJ18A mini-lathe, I'm cleaning up, extending and reorganising them. Some lathe operating experience is assumed. If in doubt, '''*ASK*''' me, Andy H<sup>*</sup> , Jonathan H or another experienced minilathe operator!<br />
<br />
''* Andy H should be asked (for an authoritative answer) any questions involving RML usage policies or acquiring tooling or materials through RML.''<br />
<br />
== The Lathe ==<br />
Our Facilities page [[Facilities#Lathe|has]]:<br />
<blockquote><br />
'''Lathe'''<br />
[[File: Lathe2.jpg |200px|right | Lathe]]<br />
In the kitchen. <br />
<br />
Marked as a CJ18A Mini-Lathe from [[https://www.amadeal.co.uk/acatalog/CJ18A-Mini-Lathe-7x14-Machine-100mm-3jaw-Metric-With-Metal-Gears-AMA_LA_CJ18_M_3_MGRB.html Amadeal]]<br />
[[https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Manual]] <br />
<br />
[[Media:Lathe InductionNotes.pdf| Induction Document]]<br />
<br />
Possible upgrades:<br />
*https://www.youtube.com/watch?v=GwT-JQLbNPA<br />
<br />
''Please do not use the lathe until you have received induction'' <br />
<br clear=all><br />
</blockquote><br />
Its a Chinese import 7x14 mini-lathe. The 7x14 refers to the maximum diameter and length of work, in inches and is only a theoretical measure of the working envelope as you loose length to the chuck + any tailstock tooling, and the diameter is over the bed, not the cross-slide. See actual specifications below. <br />
<br />
Most if not all Chinese 7x10 to 7x16 mini-lathes seem to be remarkably similar (not uncommon with Chinese products due to [https://www.bunniestudios.com/blog/?p=284 Shanzhai (山寨)] )<br />
and the OEM of our Amadeal CJ18A Mini-Lathe was probably [https://www.made-in-china.com/showroom/cheap-lathe Yangzhou Realbull Machinery Co. Ltd]. Very similar lathes are also made by [https://www.siegind.com/lathe-machine.html Sieg], but their lathes tend to be slightly less sophisticated than the equivalent Realbull models.<br />
<br />
''N.B. Many Sieg parts are known to have slight but critical differences from Realbull parts, so '''DON'T''' order Sieg spares for a Realbull lathe!<br />
<br />
== Key Specifications ==<br />
Amadeal says the CJ18A Mini-Lathe is a 7x14 model with:<br />
<blockquote><br />
* Power 550 W<br />
* Distance between centres : 350 mm<br />
* Swing Over Bed: 180 mm<br />
* Swing Over Cross Slide: 110 mm<br />
* Taper: MT3<br />
* Tailstock Taper: MT2<br />
* Chuck diameter: 100 mm<br />
* Spindle Speed: 50 - 2500 rpm ''(with digital readout)''<br />
* Spindle Bore: 20 mm<br />
* Cross slide Travel: 65 mm<br />
* Range of Metric Threads: 0.5 - 2.5mm.<br />
</blockquote><br />
* The lead screw is metric, pitch 1.5 mm.<br />
* The spindle center is 90.6 mm above the flat of the bed (measured).<br />
<br />
Even though the compound and cross slide handwheels appear to be calibrated in thousandths of an inch, as ours is a metric machine, they only approximate that. One turn of a slide handwheel is 1mm advance, and they have 40 divisions, so each division is 0.025 mm, (approx. 0.984 [https://en.wikipedia.org/wiki/Thousandth_of_an_inch thou]). Similarly, the tailstock quill advances 1.25 mm per handwheel turn, which has 50 division dial, giving the same 0.025 mm divisions, but only 4 turns per 5 mm. The carriage handwheel is awkward - it moves approx. 19.2 mm per turn, and doesn't have a dial scale.<br />
<br />
== Notable Accessories ==<br />
We have:<br />
* [https://www.amadeal.co.uk/acatalog/160mm-Face-Plate-for-the-4-Mini-lathe-AMA_AC_CJ18A_FP160RB.html#SID=129 160 mm (6 1/4") Faceplate]<br />
* 100 mm (4") three jaw self-centering chuck (OEM standard) 22.5mm bore, with inside and outside jaw sets<br />
* 100 mm (4") four jaw (independent) chuck with reversible jaws (8 TPI screws)<br />
* Tailstock drill chuck (max. 13 mm dia.)<br />
* Live center for tailstock (+ OEM fixed center) <br />
* Four way Tool Post (OEM Standard)<br />
* [https://www.amadeal.co.uk/acatalog/Quick_Change_Tool_Post_for_the_mini-lathe.html Quick Change Tool Post] + 3 tool holders<br />
* [https://www.amadeal.co.uk/acatalog/Fixed-Steady-for-Mini-Lathes-AMA_AC_CJ18A_FSRB.html#SID=145 Fixed Steady Rest]<br />
* [https://www.amadeal.co.uk/acatalog/Travelling-Rest-for-Mini-Lathes-AMA_AC_CJ18_TSRB.html#SID=144 Travelling Steady Rest]<br />
<br />
''You'll find all of the above on the shelf above the lathe, with the accessories in the wooden box, apart from the steadies, which live next to it. Change gears, spare parts, and most cutting tool tips/blanks are in labelled white rectangular tins behind the lathe.''<br />
=== Measuring Tools ===<br />
We have:<br />
* Various dial indicators - the one with the adjustable magnetic base stand is the most convenient for most lathe setup work.<br />
* 25mm micrometer (in little grey case)<br />
* Grey case containing set of measurement tools including dial calipers, micrometer, steel rule (metric & inch), engineers square, and a fish-tail gauge<br />
<br />
''We currently lack''<br />
* ''A tool height setting gauge''<br />
<br />
=== Hand Tools ===<br />
Some common tools needed for normal use are kept with the lathe, in or attached to the wooden accessories box:<br />
* 2 mm Allen key - adjusting cross-slide and compound gibs<br />
* 4 mm Allen key - quick change toolholder tool clamping screws + height adjust, tightening dials<br />
* 5 mm Allen key - four way toolpost tool clamping screws, engaging/disengaging threading indicator<br />
* 6 mm Allen key - locking/unlocking quick change toolholder<br />
* 8 mm spanner - locking carriage when 8 mm socket can't be used, locking gib adjuster nuts <br />
* 13 mm spanner - changing chucks, locking steady rest jaws<br />
* Very long needle nose pliers - for grabbing swarf safely, holding one end of emery cloth safely so you can keep your fingers away from the jaws, and extricating small objects from awkward places.<br />
<br />
== Change Gears ==<br />
[[File:BC puller 1.jpg|thumb|Custom puller for B-C stub shaft]] [[File:BC puller 2.jpg|thumb|Pulling the B-C stub shaft]]<br />
See "Conquest Super Lathe" manual ([[#Manuals|below]]), section '''4.7 Change Gears''', PDF pages 28-29, but see below for mesh adjustment. The LittleMachineShop.com "Mini Lathe User’s Guide" (also below) section '''Threading''' gives a far better explanation, with pictures and diagrams, but its for a lathe with a US 1/16 inch pitch leadscrew, not a metric 1.5 mm pitch one like ours, so you *MUST* ignore all the tables in that section, replacing them with metric mini-lathe (with 1.5 mm pitch leadscrew) equivalents. <br />
<br />
We have the following tooth count gears: 20,20, 30, 35, 40,40, 45, 50,50, 60,60, 80,80<br />
which consist of the OEM power feed gears + the metric change gear set. Apart from the metal 20 tooth pinions, they are all plastic, probably Delrin if the molded in 'POM' marking can be trusted, but possibly plain Nylon 6, and are metric Module 1.<br />
<br />
If we wanted to add the capability to cut US/Imperial threads we'd need to buy additional 55, 57 and 65 tooth gears, and possibly a 21 tooth metal pinion.<br />
<br />
CGTK's [https://www.cgtk.co.uk/metalwork/calculators/changegears/minilathe?gears1=20,20,30,35,40,40,45&gears2=50,50,60,60,80,80&gears3= Change Gear Calculator] ''(link preloaded with our gear list)'' is useful if you don't want to calculate the ratios from first principles. Not all suggested combos will physically fit.<br />
<br />
* Take care *NOT* to loose the keys in the A and D shaft keyways - turn each shaft till the keyway is up before removing the gear. <br />
* The B and C gears are coupled by a hollow stub shaft (with an integral key), which is so tight in the gears it has to be pressed or driven out - I've made a puller just for this task, kept in the change gears tin.<br />
* The center of the B-C stub shaft *MUST* be lubricated where it runs on its pin on the change gear banjo bracket, with grease or heavy oil. ''Seizure of the stub shaft due to running dry is a frequent cause of catastrophic mini-lathe geartrain failures!''<br />
* Don't get oil on the change gears as it can cause plastic gears to crack. Only PTFE drylube or plastic compatible white grease should be used on their teeth. <br />
* Adjust the B-C pin position in the straight slot first to set the C to D gear mesh, tighten its nut, then swing the whole banjo about the D shaft boss to set the A to B mesh, and finally tighten the banjo clamping nut.<br />
* Check both gear meshes have running clearance by turning the chuck by hand enough to complete one full turn of the leadscrew, and by attempting to turn the intermediate gear(s) to assess backlash, If excessive resistance is felt or if there's significant backlash, readjust the gears. If you have difficulty judging the mesh, a strip of 80 gsm copier paper (approx. 0.1 mm thick) wound into the meshing teeth before tightening the stud or banjo will give appropriate clearance once removed. Once setup, check the gears run quietly under power.<br />
* If the sum of the tooth counts C+D is the same as for the ones you just removed and they were correctly meshed, you don't need to move the stub shaft pin. If A+B is <u>also</u> the same, you don't need to move the banjo. e.g. If it was set up for 16:1 reduction power feed, 1 mm (40:60 - 50:50) for M6 and 1.5 mm (e.g. 40:60:40) for M10 pitches can thus be achieved by only swapping gears. <br />
<br />
''The change gears, puller, etc. and a box spanner for the banjo nut are kept in a white rectangular tin behind the lathe.''<br />
<br />
=== Power Feed ===<br />
When used for turning with power feed, the change gears should be set for a 16:1 reduction (A:20 : B:80 - C:20 : D:80) using the pair of small metal 20 tooth pinions and the 80 tooth plastic gears (largest in set), for a feed of 0.09375 mm per turn (1.5 mm/16). Unless continuing your threading project the next session, please re-fit the 16:1 power feed set after threading so the power feed is ready for use. <br />
<br />
* *ALWAYS* leave the feed direction selector lever in its neutral (no feed) position, and the half-nuts open after use.<br />
* *ALWAYS* check the carriage lock is disengaged before engaging power feed. Unlock the carriage after use. <br />
<br />
=== Threading Dial ===<br />
The threading dial is an aid to re-engaging the half-nuts at the right moment so the tool will retrace its previous path cutting deeper, rather than offsetting axially some fraction of the thread pitch and ruining your work. Its based on the concept of the lowest integer multiples of the leadscrew and thread ''(being cut)'' pitches that exactly match, but for mechanical simplicity it only covers certain selected multiples of the leadscrew pitch.<br />
<br />
We have a choice of three pinion gears:<br />
{| class=wikitable<br />
|+ Threading dial Pinion Gears<br />
|-<br />
! Teeth !! Colour Dot !! Usable lines !! OD gear !! Dist. per turn<br />
|-<br />
| 14 || Red || 1,7 || 7.51 mm || 21 mm<br />
|-<br />
| 15 || Orange || 1,5,9 || 8.05 mm || 22.5 mm<br />
|-<br />
| 16 || Green || 1,4,7,10 || 8.37 mm || 24 mm (2 mm/div)<br />
|}<br />
They are now colour coded, with a paint dot on the gear end face ''(the only non-wear surface)''. The 16 tooth one is normally left on the lathe, but disengaged when not threading to minimise wear on the lead screw. The others are kept in the Change Gear tin.<br />
<br />
There's a threading dial 'pickup' calculator here: https://www.cgtk.co.uk/metalwork/calculators/threaddialindicator <br />
<br />
Initially select ''Lathe:'' '''Custom''', and enter the following below:<br />
* ''Units:'' '''Metric'''<br />
* ''Lead Screw Pitch (mm):'' '''1.5'''<br />
* ''Thread Dial Indicator Gear Teeth:'' '''16,15,14''' <br />
* ''Lines on Thread Dial Indicator:'' '''12''' <br />
* ''Line Marking:'' '''Every Line Numbered'''<br />
Note the teeth list is entered in reverse order so the resulting table highlights any required pinion changes.<br />
<br />
N.B. The dial is only friction clamped to the pinion by its center screw. If you have any reason to suspect it may not be properly aligned: <br />
# With the power off and the carriage unlocked, engage the feed direction lever upwards. You'll probably need to turn the chuck by hand to get it to engage.<br />
# If the threading indicator isn't already engaged, loosen the threading dial support block bolt, pivot the block to engage the pinion with the leadscrew and retighten the bolt.<br />
# Engage the half nuts, again turning the chuck by hand till they drop in. <br />
# Turn the chuck a couple of turns, top towards you to take up any backlash, then lock the carriage, taking care not to push it left while locking it.<br />
# Loosen the screw securing the dial to the pinion.<br />
# Align the '1' line of the dial with the index line, by rotating the dial clockwise, then retighten the screw.<br />
# Don't forget to disengage half-nuts and unlock the carriage!<br />
<br />
The above instructions should result in the half-nuts engaging cleanly when exactly on any valid line when threading towards the headstock. If it is required to thread away from the headstock, there will be a slight offset from the line due to backlash between the spindle gear and leadscrew, so engage slightly early.<br />
<br />
Changing the pinion:<br />
# Loosen the threading dial support block bolt and disengage from the leadscrew.<br />
# Undo dial center screw, and remove it and the dial, dropping the old pinion out the bottom.<br />
# Oil the shaft of the new pinion with a drop of light oil and insert it from below, gear end down.<br />
# Refit dial and screw.<br />
# Check the dial and pinion turn freely with minimal resistance.<br />
# Align as above.<br />
<br />
== Tailstock and Steadies ==<br />
These are mostly used to support long work ''(long with respect to its diameter)'' to improve rigidity, increasing accuracy and reducing chatter. The Tailstock quill is also used with a drill chuck for drilling.<br />
=== Tailstock ===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock base]]<br />
The tailstock can be offset to turn shallow tapers between centers. We don't currently have the accessories to turn between centers, namely <s>a MT3 dead center for the spindle, or</s> any drive dogs for the work. Also realigning the tailstock after turning a taper can be a PITA. The photo shows the tailstock adjusting screw locations ''(C - Lateral, and D - Skew)'' and the block on the baseplate they engage with. Adjustments can only take effect when the tailstock locking lever is eased to take the pressure off the baseplate. As we don't have a MT3 center, one has to turn a fresh point on a test workpiece for a rough tailstock alignment reference. Fine alignment, to avoid inadvertent taper turning, can be done by mounting a long precision ground bar between the chuck (or preferably a center in the spindle), and a dead center in the tailstock and sweeping it with a dial indicator on the carriage. Finally a test cut should be taken at either end of a bar between centers, and the diameters checked with a micrometer. Assuming the bed has previously been properly levelled and shimmed to take out twist ''(not the case at RML as we don't have it bolted down)'', any remaining difference in diameter will be double the tailstock offset, smaller at the tailstock being offset towards the front. Fine adjustment cant be achieved by jacking with the screws, its best to ease the adjusting screws, bump the tailstock into alignment then take up the screws again, checking the alignment is maintained when the tailstock is unlocked and relocked. There is no vertical adjustment, though shims can be added between the tailstock and its base.<br />
<br />
==== Tailstock Quill ====<br />
There is a metric/imperial scale on the top of the quill, read against the end of the tailstock, for depth measurement when drilling. The tailstock quill has a 1.25 mm pitch thread and a 50 division dial. Each division is therefore 0.025 mm, and it only takes 4 full turns of the handwheel to move the quill 5 mm. <br />
<br />
To eject MT2 taper tooling and centers from the tailstock, wind the quill all the way in.<br />
<br />
N.B. The quill anti-rotation pin (dog-tip setscrew + locking nut in top of tailstock near to the quill lock) is only M5. It will sheer if a large diameter drill jams in the work. Please back it out clear of its keyway if using large drills, and use alternative methods of preventing chuck rotation. To re-engage it, crank the quill out till you can see the keyway, align it with the screw and screw in the screw till it gently bottoms out, then back it off a quarter turn. Try twisting the quill to check its properly engaged, then tighten the locking nut gently to hold the screw in position clear of the bottom of the keyway.<br />
<br />
=== Steady Rests ===<br />
We have two, both with brass tips that must be kept lubricated during use.<br />
<br />
The fixed steady mounts on the ways, and is most useful when turning longer work that wont fit through the spindle bore. Adjustment is critical, and the surface the tips run on must be smooth and concentric, as any misalignment that forces the work off center will result in the work wobbling in the chuck, marring it, with a high risk of it becoming un-chucked, which can be dangerous at speed.<br />
<br />
The travelling steady mounts to the headstock side of the carriage to locally resist the deflection of thin long work, due to the cutting forces. It only has two tips, to resist climb, and deflection away from the tool, and requires readjustment after every cutting pass.<br />
<br />
== Tooling and Tool Holders ==<br />
'''Key dimensional data:'''<br />
* The quick change holders accept up to 10 mm shank tools. <br />
* The four way toolpost has 50 mm long sides, a seat width of 15 mm and can clamp tools of up to 5/8" (15.875 mm) shank ''(check this)'', but the slot base is only 10.4 mm below the spindle center so cannot be used with >10 mm shank tooling unless it has a dropped tip. Large tooling with a centered tip is also problematic as you run out of height above the shank when trying to shim to match the spindle center height. <br />
<br />
===Quick Change Toolpost===<br />
I've got the quick change toolpost and toolholders setup for mostly easy use. The three toolholders came with cantilever height setting arms which historically haven't been installed as the supplied fixing screws were too short. That's all now sorted out and a HSS RH turning tool and a HSS hand-ground grooving/parting-off tool are now mounted in two of the holders and set to height. The third is kept free for other tools. <br />
<br />
The quick change toolpost has been modified with a spring to press the dovetail clamp outwards and help stop it twisting or flopping about to ease toolholder fitting and removal. The dovetail clamp (socket headed screw on toolpost side opposite dovetail) feels a bit stiffer than before, but will take less than half a turn to go from open (with the toolholder lifting out or dropping in easily) to fully clamped. As there is so much less clearance in the open position you should no longer need to wiggle the toolholder while clamping it to get a consistent height. If the dovetail clamp ever gets misaligned, twist it straight by eye, slacken off a bit further than usual to get a toolholder on, clamp it to align the dovetail then release, reseat the toolholder and re-clamp to ensure its at its preset height. You cant adjust the height by 'jacking' with the height screw due to its offset leverage. Instead, back off the height screw and hold the toolholder at the desired height while locking the dovetail clamp, then adjust the height screw (and locking nut) to hold it there, then check it doesnt change height significantly when you unclamp and reclamp the dovetail. <br />
<br />
Unfortunately the OEM height setting screws foul the toolpost locking nut handle. Currently, if you need to swap toolposts you will have to first remove the quick-change tool holder from the post. There is enough nut handle swing to allow the quick change toolpost to be unclamped and rotated to fine set the tool angle without removing the toolholder. It also seems the mating surfaces may be slightly out of square, as if you rotate the toolpost 90° or 180°, the nut swing may be insufficient to re-clamp it without removing the toolholder to do so. Add a M10 washer under the locking nut if the handle ends up pointing in an undesirable direction! A thin M10 washer is kept with the toolpost collar for this purpose, and will shift the handle position by about a third of a turn. <br />
<br />
''ToDo: Make a taller nut of a similar pattern, to clear the height setting screws.''<br />
<br />
===Four Way Toolpost===<br />
The OEM four way toolpost is significantly more rigid than the quick change toolpost + holders because it has fewer and thicker parts and less overhang. Therefore the four way toolpost should be used when using carbide tooling. It requires shimming under the tool to set the tip height to the spindle center height - see below. The tool shanks are mostly significantly less than 15 mm wide, so need to be centered under its clamping screws, tempting as it is push the shank in for full side contact with the toolpost. If possible clamp the shank with all three screws not just two.<br />
<br />
==== Shimming ====<br />
We typically only mount up to two tools, and want maximum rigidity, so use 50 mm x 15 mm shims, (the full seat area), preferably with deburred edges and radiused corners so they aren't a hazard to the operator.<br />
<br />
We have pre-cut and marked shims of the following thicknesses: <br />
* 1x 3.23 mm, 2.42 mm, 1.56 mm, 0.32 mm, and 0.25 mm<br />
* 2x 1.00 mm, 0.77 mm, 0.12 mm, 0.11 mm, 0.10 mm and 0.05 mm<br />
* 4x 0.53 mm<br />
<br />
Our shims are mostly found materials (hence the awkward thicknesses) and are mostly a mixture of aluminium and steel, with a couple of GRP ones. The toolpost seat '''<u>must be absolutely clean</u>''' to avoid embedding debris in the aluminium or GRP shims, to get a consistent height and avoid tilting the tool - wipe it every time you change a tool! Put the thin shims at the bottom of the stack to avoid the tool shank edges creasing them. Shims are kept in a little yellow plastic box with a clear lid, near the carbide tools case.<br />
<br />
I made a tool height setting gauge (T shaped black acrylic with steps in its sides) which can be used to check the tool tip height matches the spindle center height using either the flat of the ways or the saddle as a reference. The tool tip should just fit under the lip of the appropriate step, with the T arms across the ways flats or on the saddle. It is kept in the box with the carbide insert tools.<br />
<br />
''ToDo:'' <br />
<br />
* ''Cut more shims neatly, mark them with their thickness.''<br />
* <s>''Do test cuts and start noting shim stack-ups for various tools.''</s><br />
* ''Organise shim storage!''<br />
<br />
=== HSS Tools ===<br />
[[File:Tool Bit Geometry.jpeg|thumb|Single point cutting tool geometry]]<br />
Our HSS tools are made from 8 mm square bar stock, hand-ground to tip profile in-house. See LittleMachineShop's [https://littlemachineshop.com/images/gallery/instructions/grindingtoolbits.pdf Grinding Tool Bits] notes. <br />
<br />
I've installed our usual HSS LH turning and parting off tools in two of the quick change holders and set the heights correctly. There are a couple of other HSS tools or tool blanks knocking about. Taking heavy cuts turning steel (even with good cutting oil) blunts HSS tools fairly quickly, which are time-consuming to re-sharpen nicely without a dedicated tool & cutter grinder with appropriate jigs. Its worth noting that the usual 'speeds & feeds' tables are commonly based on surface speeds expected to give a half hour (active cutting) tool life before resharpening.<br />
<br />
I touched up the LH turning tool by lapping on wet & dry (silicon carbide) paper on glass (Aka: [https://en.wikipedia.org/wiki/Scary_sharp 'Scary Sharp']) working upwards through the grits 200, 400, 600 and finally 1000, initially 'bluing' the surfaces to be lapped with a marker pen to see which areas needed taking down more. The end of the tool was significantly uneven so I touched that up freehand on the bench grinder to flatten it when it became apparent that 200 grit lapping wasn't cutting where it needed to. There was an existing micro-bevel on the leading side, which I kept. Finally I 'dubbed' the leading corner vertical edge on the 1000 grit to give it a very slight nose radius. A test cut on brass gave a very nice finish when turning.<br />
<br />
''Ian B has purchased some spare 8mm HSS tool blanks - talk to a lathe trainer if your proposed lathe work needs custom ground HSS tooling.'''<br />
<br />
=== Brazed Tungsten Carbide Tools ===<br />
Somewhat of a half-way house between hand ground HSS tooling and insert tooling with the disadvantages of both and some more besides - e.g. they are much harder to sharpen. So why do we bother? Some tool geometries would be awkward and tedious to hand grind, and Chinese import brazed carbide tooling is about half the price of similar HSS tooling, and far more readily available. Also, for space constrained tooling like boring bars, if you want carbide, for insert tooling, the size of the insert and its clamping seriously limits the minimum hole diameter you can work in. I have purchased a set of 3/8" shank brazed carbide tipped boring bars, but we currently cant sharpen them, due to lack of a diamond grinding wheel. <br />
<br />
=== Tungsten Carbide Insert Tools===<br />
Decoding ISO insert tooling part numbers: https://www.cutwel.co.uk/blog/learn-the-turning-tool-iso-code-system<br />
[[File:Carbide set.jpg|800px|thumb|left|Our set of Tungsten carbide insert lathe tools (before the new inserts were fitted)]]<br />
<br />
{| class=wikitable<br />
|+ Tools, left to right, (+ last across top):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| SSKCR0610H06 || 75° through boring || SCMT06204 || Long || 6 || 6.34 || ''4.33''<br />
|-<br />
| SSSCR0610H06 || 45° deep facing, internal chamfering || SCMT06204 || Long || 6 || 6.13 || ''4.58''<br />
|-<br />
| SWUCR0610H05 || 93° boring, deep facing || WCMT050308 || Long || 6 || 6.22 || ''4.48''<br />
|-<br />
| SWGCR0810E05 || 90° RH turning & facing || WCMT050308 || Short || 8 || 8.25 || '''2.45'''<br />
|-<br />
| SSSCR0610E06 || 45° turning, chamfering || SCMT06204 || Short || 8 || 8.75 || ''1.93''<br />
|-<br />
| SSBCR0610E06 || 75° RH turning, chamfering || SCMT06204 || Short || 8 || 8.72 || ''1.98''<br />
|-<br />
| LW0810R-04 || 60° external threading || JCL15-120 || Short || 8 || 7.44 * || ''3.28''<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || 8.23 || ''2.5 ?''<br />
|-<br />
| LN0813R-04 || 60° internal threading || JCL15-120 || Long || 7.95 || 7.44 * || ''3.28''<br />
|}<br />
<br />
{| class=wikitable<br />
|+ More Tools, (loose in tin):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || ~8.5 (not in use) ||<br />
|-<br />
| [https://www.glanze.co.uk/product/glanze-12-mm-60-degree-metric-internal-threading-tool/ Glanse SIR0012K11] || 60° internal threading bar || 11IRA60 || Long || 12 dia || ??? || ???<br />
|}<br />
''Shim stack heights in bold are tested, in italic are only calculated.'' ''Tip heights marked * are with new JCL15-120I inserts. The single remaining plain JCL15-120 insert has a slightly higher tip height.''<br />
<br />
Carbide tooling typically requires two to three times more speed than HSS and at least a couple of 'thou' depth of cut for best results.<br />
<br />
Chatter can rapidly kill carbide tooling by chipping the cutting edge. To improve rigidity and reduce the risk of chatter, the cross-slide and compound gib screws need to be well adjusted so there is minimal play in the slides, tool stick-out should be minimised, the four way toolpost should be kept over the cross-slide, and the work should be kept close to the chuck (or otherwise supported by tailstock or steady rest) to avoid excessive deflection.<br />
<br />
Thermal shock is almost instant death to carbide, and when dry cutting the insert tip can run very hot, so do not add extra cutting fluid manually during the cut. Pre-apply what you need, evenly, before starting the cut.<br />
<br />
Parting off or facing to center is high risk - if the tool tip is even slightly below center or if tool or work deflection takes it below center, the work will tend to climb over the tool tip as the cut approaches center, breaking the insert. To avoid this, the tool should be shimmed slightly above center, sufficient to allow for work and tool deflection, and unless very close to the chuck, a steady should be used. Its often preferable to part to a couple of mm dia. remaining then stop and saw through the remainder. Parting off hollow parts is much lower risk.<br />
<br />
Further investigation of the Tungsten carbide insert tool height situation is not encouraging - the so-called 'set' in question does not have a consistent tip height ''(see above table)''! In a real set, the insert seats *should* be machined allowing for the insert thickness to bring all the cutting edges to the same height with respect to the shank underside. However if you place them tip to tip on a table its easy to see there is considerable height variation, so they need to be individually shimmed (or at best, one machined shim will only be right for two or three tools). At this time we don't have dedicated shim stacks for each tool.<br />
<br />
A 2.42 mm thick shim brings the SWGCR0810E05 90° RH turning & facing tool almost exactly to center height, and good results were obtained turning 1" steel pipe. However facing 50mm steel bar stock to center found it to be slightly low, leaving a fractionally under 0.05 mm 'pip' so it needs another 0.03 mm to bring it fractionally above center. Fractionally too high is generally preferable to fractionally too low, due to tool deflection, so adding an 0.05 mm shim to the stack should produce optimum results.<br />
<br />
==== Inserts ====<br />
Ian B has purchased the spare inserts we needed in sets of five. He even was able to get the CK3 parting-off inserts which had been difficult to source!<br />
<br />
Inserts used in above tool set:<br />
* 3x SCMT06204 (square, indexable) https://www.rdgtools.co.uk/acatalog/SCMT-06-Carbide-Insert.html<br />
* 2x WCMT050308 (triangular, indexable) https://www.rdgtools.co.uk/acatalog/WCMT-05-T3-08-5XTIP-8813.html<br />
* 2x JCL15-120 (60 deg threading point) https://www.rdgtools.co.uk/acatalog/X5-JCL-15-120L-THREADING-TIPS-60-DEGREE--X5-TIP---23455.html<br />
* CK3 (parting off) https://www.rdgtools.co.uk/acatalog/CK3-CARBIDE-TIPS---PARTING--BOX-OF-5PCS--9437.html<br />
<br />
Inserts used in other tools:<br />
* 1x CK3 (as above) also missing from spare parting off tool<br />
* 1x 11IRA60 in Glanse threading bar + 1x spare<br />
<br />
=== Drills ===<br />
Various sizes of center drills are kept in a plastic bag next to the wooden accessories tray. There's also a small box of 2.5 mm center drills.<br />
<br />
We have a set of 11 TiN coated HSS drill bits from 1.5 to 8 mm, (in a cylindrical plastic index box) for tailstock drilling of brass, aluminium and non-abrasive plastics. To keep them sharp enough for the precision work we expect from the lathe, please don't use them for steel or reinforced plastics, and don't borrow them for non-lathe use. Metric and US [https://littlemachineshop.com/reference/numberdrillsize.php numbered]/[https://littlemachineshop.com/reference/letterdrillsize.php lettered] general use HSS drill bits are kept in two red metal index boxes next to the drill press.<br />
<br />
== Using the Lathe ==<br />
=== General ===<br />
A cutting speed chart for HSS tooling, published by Model Engineer magazine can be found [https://www.model-engineer.co.uk/sites/7/documents/cutting%20speed%20chart.pdf [here<nowiki>]</nowiki>]. The second row is the target feed rate and the rest of the chart, apart from the diameter column is RPM.<br />
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For carbide tooling cutting iron and steels, recommended speeds are generally three times higher than for HSS, but the CJ18A 2500 RPM max. spindle speed (in high gear) means you can only reach the optimum speed range for over 15 mm dia work. For small diameter work, HSS tooling may well be a better choice.<br />
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An online metric speeds calculator is here: https://www.cgtk.co.uk/metalwork/calculators/cuttingspeeds <br />
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How to do the maths to calculate speeds and feeds: https://www.cutwel.co.uk/blog/speeds-feeds-made-easy<br />
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Making dimensioned parts is primarily done by touching off the tool tip on a reference surface (with the lathe stopped, turning the chuck by hand), zeroing the handwheel dial, then manually counting turns and divisions. When backing off the tool its best to do so by exactly one whole turn so you don't forget the previous dial position. Stopping and measuring the work before taking the final cuts is essential if high accuracy is required. ''I've changed out the dial setscrews for flat tip ones with a tiny slug of solder under them so the dials are now friction fit on their shafts. i.e. if you hold the handle firmly taking up the backlash in the direction of cut, you can zero the dial just by grabbing and twisting it.''<br />
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Carriage movement is less easy to measure as the handwheel is uncalibrated and advances an awkward bit over 19.2 mm per turn. Your options here when shoulders or other features must be exactly positioned are, in order of increasing accuracy: <br />
* Use measuring instruments, scribe the work at the desired length then work to the scribed line. Its often convenient to black the work with a permanent marker, then scribe with the tool tip, turning the chuck by hand.<br />
* for short distances, lock the carriage and use the compound, set parallel to the work<br />
* Set up a long travel dial indicator to measure carriage motion. <br />
N.B. with the leadscrew stopped, and the threading dial engaged, with its default 16 tooth gear, it will make one turn for every 24 mm of carriage movement (2 mm/div). This isn't accurate enough for positioning but is sufficient to check you aren't out by a whole mm or more.<br />
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Do not allow any solvents to contact the chuck guard clear plastic as it will make the plastic brittle, or even craze it, and try to avoid melting it with the work light!<br />
<br />
=== Slide Locks ===<br />
* The carriage can be locked to the ways using the M5 hex screw through the top of the saddle to the left of the cross-slide. Double check the leadscrew is disengaged and the half-nuts open before locking it. Lock it when facing.<br />
* The cross slide can be locked by a M4 socket headed cap screw just in front of its middle gib screw. Locking the cross slide is helpful when turning very shallow conical features where the cross slide handle is in the way of the compound.<br />
* The compound slide can be locked by a M4 socket headed cap screw in line with the edge of the toolpost mount on the side with the gib adjustment screws. In normal use it should be kept backed off half a turn but it is desirable to tighten it for parting off operations to keep the resulting end faces flat.<br />
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=== Chucks and Chuck Jaws ===<br />
==== Terminology ====<br />
* Inside jaws have steps on the outside to grip the ID of hollow work, but can also be used as outside jaws on small diameter parts (i.e. that fit through the spindle). <br />
* Outside jaws have steps on the inside to grip the OD of the work.<br />
* Universal chucks have a scroll plate with a spiral screw thread that moves all the jaws.<br />
* Independent chucks have individual adjusting screws for each jaw.<br />
<br />
==== The Chucks ====<br />
* The three jaw universal chuck can only grip near round or hexagonal work, which it centers, but its concentricity is not perfect so e.g. if you reverse the work and continue turning at the same diameter from the other end, you will see a line where the turned surfaces meet. It has separate sets of inside and outside jaws, and we normally keep the inside set installed to use as outside jaws for small diameter work.<br />
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** Our jaws are individually numbered, stamped in the groove. They must be fitted in the correct sequence. The jaw slots are not clearly marked. Lowest runout for small dia. parts is achieved if you fit the jaws with #1 anticlockwise of the makers mark, then continue anticlockwise for #2 and #3.<br />
** A large strong rubber band is a great help getting all the jaws started on the scroll together - with slots #1 and #3 above the centerline and the scroll thread outer tip between #1 and #3, insert jaws #1 and #2 and put the rubber band round them to keep them in their slots. Insert jaw #3 and stretch the rubber band over it to hold it up into its slot. If the scroll was positioned correctly, all jaws should be at the same initial radius. The jaws can now be cranked in with the chuck key and they should all engage in step so they meet in the middle.<br />
:: ''Mini-lathe.com have the best instructions for [https://www.mini-lathe.com/mini_lathe/chucks/chucks.htm#Installing_Chuck_Jaws changing the jaws].'' <br />
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* The four independent jaw chuck can grip most roundish or squarish work, which can either be carefully centered by the user, or deliberately gripped off-center. <br />
** Its jaws are reversible so can be swapped from inside to outside by simply cranking each jaw out and reinserting it the other way round, one at a time. DON'T move the jaws to different slots as they are likely to bind.<br />
** When setting up to face the sides of rectangular objects held crossways, it may be helpful to use both inside and outside jaw orientations, in symmetrical opposing pairs.<br />
** Its screws move their jaw 1/8" (3.125 mm) per turn<br />
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* The jaws must '''never''' protrude from the chuck OD by more than one step, and for safety, its preferable they don't protrude at all, as they make the gap between the front of the bed and the chuck body an even more unforgiving meat grinder, and as the number of teeth engaged with the scroll or screw decreases, they loose strength, just when you need it the most to grip larger/heavier work. <br />
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''Neither chuck is well suited to gripping tapered work safely. When seating work that doesn't quite fit through the chuck bore (which is larger than the 20mm spindle bore limit), be careful that it isn't seating on the chamfered edge of the chuck bore as it is far to easy to get the work slightly cocked so it doesn't run true.''<br />
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==== Changing Chucks ====<br />
* When changing chucks, use the small grey plastic mat to protect the ways under the jaws in case you drop the chuck.<br />
* The spindle nose has two patterns of holes - the three hole pattern is for the three jaw chuck and the faceplate, and the four hole pattern is for the four jaw chuck. One hole is shared between the patterns, and is marked on the spindle nose.<br />
* To fit a chuck:<br />
** First check that the spindle nose and chuck back and recess are free of swarf, grit or other debris. Any foreign objects will tilt the chuck causing excessive runout and may mar the surfaces.<br />
** Remove the nuts and split lock washers from its studs, line its studs up with the hole pattern (preferably with the stud nearest anticlockwise to the makers mark through the marked spindle hole), fit and hold it in place with your right hand, and with your left, get the lock washer and nut on the top stud, and take up the slack.<br />
** One one nut is on, you no longer have to worry about dropping it, and can work round fitting the remaining washers and nuts, taking up the slack on each as you fit it. <br />
** Next, work round again getting them all finger tight, then tighten them gently, and finally work round fully tightening them. <br />
* Removal is the reverse of refitting. Put the washers and nuts back on the chuck's studs so they don't get lost.<br />
<br />
=== Faceplate Work ===<br />
Faceplate work is probably the most dangerous operation you can (or rather should) perform on a lathe. The working area is a large diameter spinning surface with protruding clamps to fixture the part that it is impractical to guard. Protruding clamps, studs, nuts etc. are very difficult to see at speed.<br />
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'''Treat the faceplate with great respect and caution if you wish to continue to be able to count to ten on your fingers!''' <br />
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The 65 mm cross-slide travel vs the 80 mm faceplate radius is a serious limitation that may require creative compound, toolpost and tool setups for larger parts, and doing full face cuts in two sections.<br />
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''It is common practice to skim the faceplate to ensure it runs true. We have not (yet) done this, and wont till the spindle is in better bearings and the nose reground to minimise runout.''<br />
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==== Clamping ====<br />
Open ended/sided clamps should be oriented so that cutting forces drive the work towards the clamping bolt/stud, not out from under the clamp. Minimize the protruding length of thread past the clamping nut, if necessary using sacrificial bolts or studs you can cut to length, or even using a long M8 stud for one of the faceplate mountings, so you can get a clamp nearer to the faceplate center. Double-check all clamps are secure, manually turn the faceplate to check the work and clamps clear the ways, top-slide and toolpost, and stand out of the 'line of fire' (a disc extending from the faceplate) when spinning up the work for the first time. <br />
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If you need to machine close to a clamp, consider marking a safe limit circle on the faceplate and work with a marker pen to make it easier to see how close the cutting tool is to crash disaster. <br />
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I strongly advise reading chapter two of Tubal Cain's book "Workholding in the Lathe" several times before your first faceplate setup, and if possible get another experienced lathe user to check your first few setups before spinning them up.<br />
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==== Chuck Guard Removal ====<br />
The faceplate is too large diameter to fit under the chuck guard, but the guard has an interlock switch wqhich must be closed for the lathe to run. The guard is now fitted with wing nuts so it can be removed allowing the the interlock switch to close when using the faceplate. It *SHOULD* *ALWAYS* be refitted if a chuck is fitted, except when turning work too large to clear the guard. <br />
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''The chuck guard is primarily there to make it very difficult to start the lathe without removing the chuck key and to reduce the area of large diameter spinning surface exposed. It may slow down the projectile if a chuck sheds a jaw but is unlikely to stop it. Also it serves to contain coolant spray spun off the chuck. As we don't use flood coolant this usually isn't an issue for us. As setting up for faceplate work doesn't use a chuck key, and the most hazardous zone is the face of the faceplate, with its spinning projecting clamps, with full access required for machining operations, which a guard would not cover, the consensus is that removing the guard is an acceptable risk.''<br />
<br />
=== Turning and Facing ===<br />
We are getting good results in aluminium, brass, and even steel using HSS cutting tools in quick-change tool holders, and the ~ 94 um/turn power feed. Unfortunately due to lack of rigidity in both the machine and smaller diameter parts, if you don't want the outer end to be over diameter, a light final cut and multiple 'spring' passes will probably be required.<br />
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For aluminium, a sharp HSS tool and 0.5 mm (20 div) depth of cut gives good results with power feed for rapid stock removal. Its also easy maths as each cut takes ~ 1 mm off the diameter. Finish cuts should be much finer, 0.1 mm (4 div) is 'in the ballpark'.<br />
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For steel, using carbide insert tooling, a 0.25 mm (10 div) depth of cut is more appropriate, and with pre-applied cutting oil, gives reasonable results with power feed if you use enough speed. The maths is not quite so easy as you are only taking 0.5 mm off the diameter per pass. Again, use finer finish cuts but try to plan your cuts so the final cut is still cutting, not smearing the surface!<br />
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When facing or parting off, some skill is required to turn the cross-slide handwheel steadily to get a decent finish and to avoid shock-loading the tool tip. Increasing the spindle speed in one or more steps to keep up with the reducing diameter is advisable, but avoid speeds that cause resonances (resulting in chatter). When parting off, small through-hole parts may be caught on a thin rod chucked in the tailstock, and pre-positioned inside the work with its tip right up to the parting off position.<br />
<br />
==== Using the Steady Rests ====<br />
For the fixed steady rest, see Blondihacks' Lathe Skills #26 - How To Use a Steady Rest! [[#Youtube_Playlists_&_Videos|{below}]]<br />
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Ours doesn't have ball bearing fingers, so a smooth surface on the work and adequate lubrication are essential. The thumbscrews can only tighten the fingers, so for small adjustments outwards you need to either slack off the clamping nuts or ease them slightly and use a drift against the back of the finger's slot. Once set, check the chuck still turns freely.<br />
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The traveling steady rest needs to run on a machined surface, so at least for the first pass, must follow the tool, so its difficult to avoid using more compound slide overhang than is desirable. An initial surface should be cut next to the chuck or tailstock center before fitting the steady rest.<br />
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Both are a PITA to fit - the fixed one has to have its clamping post inserted up through the bed, and the supplied spanner is useless near the headstock, and the travelling one's mounting holes on the saddle almost invariably need swarf picked out of them.<br />
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==== Turning Between Centers ====<br />
<s>Using a MT3 to MT2 reducing sleeve, the MT2 dead center can be fitted in the spindle.</s> ''Currently the MT3 spindle taper is compromised.'' Alternatively, a soft center can be turned immediately before use in the three jaw chuck, but that must have its 60° point re-cut to concentric if the chuck is disturbed, and needs to be either large enough to bear on the chuck body, or must have a lip to bear on the end face of the jaws to take the axial thrust. Recutting the center is a PITA, as the compound angle must be set to 30° anticlockwise, then reset to a true 0° afterwards. Maybe a right-hand 30° end angle zero rake form tool is the answer, or use the carbide insert tool SSKCR0610H06 as a form tool with the toolpost rotated 15° anticlockwise.<br />
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With the MT2 live center in the tailstock quill, this gives us a center either end of the work to hold it.<br />
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We also need a drive dog similar to [https://littlemachineshop.com/products/product_view.php?ProductID=4473&category=1 this], and the corresponding drive post to bolt to the spindle nose. I have some 25mm bore thick wall iron pipe, which should do nicely. Lengths of the dog's straight tail and of the post TBD after I check how much the center protrudes. N.B. its recommended to tie the tail to the post to keep them in contact so they don't slam. ''Currently we will need to drive from the chuck jaws. Possibly use the exterior jaws with a short soft center gripped on the inside end and drive from the highest step.''<br />
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=== Drilling ===<br />
Always start with a center drill so deflection of longer bits doesn't start the hole off-center. For larger bits (> 5 mm), first drill to the web size, then to final diameter. For a precision hole, drill slightly undersize and ream to final diameter. ''Supply your own reamers!''<br />
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Caution: See note about the quill anti-rotation pin in section [[#Tailstock Quill|Tailstock Quill]] above.<br />
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=== Boring ===<br />
Caution: As the spindle doesn't extend right through the headstock housing, if boring in a through hole, chips tend to fall out the back and tumble in the spindle bore till they fall into the change gears. To avoid this, one should plug the spindle bore with a wad of paper towel or rag and when cleaning up afterwards, use a rod to push it through towards the tailstock, with the chuck jaws (if fitted) wound clear of the spindle bore.<br />
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A swivel bladed hole deburring tool (pale blue handle) can be found in the main room on the windowsill behind the drill press.<br />
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A couple of boring jobs have been bodged with an awkwardly angled turning tool and achieving acceptable effective rake with enough clearance to reach deep enough into the hole has been problematic. I reviewed the tools we had and found none suitable for starting out in a 13mm bore, the max diameter we can (easily) drill. I therefore decided to buy a set of boring bars and make a holder for them. I had difficulty finding anything affordable under 10mm shank - the best low cost option was a [https://www.amazon.co.uk/dp/B07P5LGVBX set of nine 3/8" (9.525 mm) shank brazed carbide tipped boring bars], which would be close to the max capacity of the quick change boring bar holder - if we had one! Unfortunately this holder for our specific toolpost is difficult to find except in a toolpost bundle. Another annoyance is the variable tip height of the set, varying from 1.8 mm to 2.8 mm above the center of the shank.<br />
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I therefore decided to make a boring bar holder of the [https://littlemachineshop.com/products/product_view.php?ProductID=1700 Littlemachineshop.com (USA) style] for use in the four way toolpost, as the additional rigidity will certainly help. Starting with a slightly over 50 mm length of 16 mm aluminium square bar and using the four jaw chuck , both ends were faced and an attempt was made to find its center and center drill it. It was then drilled out to ~9.8 mm after much drama due to blunt drills and drills that cut ~1mm oversize. Too big, but beggars cant be choosers as we didn't have a boring bar holder or a 3/8" reamer. Unfortunately the final hole ended up significantly off center. It was then chucked crossways and ~1 mm skimmed off its thickest side to gain clearance to allow it to be shimmed to height, then one side was slit lengthwise manually with a hacksaw.<br />
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It was fitted to the for way toolpost and loaded with a booring bar, which clamped firmly. A 0.86 mm shim stack brought the tip of the largest boring bar almost spot on center height, with the difference easily accommodated by twisting the tool slightly. The three jaw chuck was then remounted, and a piece of iron pipe chucked for a test. It cuts well and leaves a decent surface finish.<br />
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''The boring bar setup is a work in progress - talk to me before attempting to use them if you have a project that would benefit from boring..''<br />
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ToDo: get something that can sharpen tools tipped with this grade of carbide - it needs some sort of diamond (or possibly CBN) wheel as green grit silicon carbide does little more than polish it. ''N.B. diamond wheels are rapidly eroded by grinding steel, so the supporting steel seat must be undercut with a regular grinding wheel before the diamond wheel can contact it.'' <br />
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We'll also need 50 mm square sheet shims to fit under the toolpost to gain clearance in the toolpost above the tool or toolholder. A 2.4 mm shim would give us about the same above and below spindle center height, and we probably need a small selection of thinner ones.<br />
<br />
=== Thread Cutting ===<br />
The objective is to cut a thread that complies with the ISO metric thread profile. Our lathe is not currently equipped to cut non-metric threads, (with the exception of BA which have pitches based on metric threads of that era).<br />
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[[File:ISO and UTS Thread Dimensions.svg|frame|center|Metric Thread Profile - from the geometry, H is ~86.6% of P]]<br />
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Metric thread data - See 'Preferred Sizes' at: https://en.wikipedia.org/wiki/ISO_metric_screw_thread<br />
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See "Mini Lathe User’s Guide" section '''Threading''' for general techniques *ONLY*, and above for change gears and threading dial setup.<br />
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Amadeal specify the max. thread pitch as 2.5 mm. Any thread pitch greater than 1.5 nn requires the change gears to gear up. When gearing up it is desirable to distribute the ratio as evenly as possible over the two pairs of gears in the geartrain to avoid excessive tooth loading.<br />
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==== External Threading ====<br />
Initially turn work to required Major Diameter, set up change gears and threading tool, touch off on the work, zero the top and cross slide dials, and do a 'scratch' pass to check the pitch. Back off the tool, return the carriage, and re-engage the half nuts on a valid dial line clear of the end of the thread then immediately stop the lathe, and hand turn the chuck till the tool tip is (hopefully) over the scratch to check the thread pickup. If all is good, return the carriage again, restart the lathe and start cutting your thread. <br />
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Methods of doing so vary depending on the size of the thread and toughness of the metal, but straight-in plunge cutting is generally to be avoided as has the highest cutting forces, and does not reliably keep the carriage (and top-slide if set parallel to the work) loaded to avoid pitch errors due to backlash. <br />
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If leaving the half-nuts engaged and reversing the lathe to return to the start of the thread for the next pass, its absolutely essential to back the tool out of the thread for the return pass as it will not follow the path of the cutting pass due to backlash in the geartrain, leadscrew mounts and half-nuts.<br />
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==== Internal Threading ====<br />
''<nothing here yet>''<br />
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== Cutting fluids ==<br />
=== Why bother? ===<br />
[https://youtu.be/mRuSYQ5Npek Watch this video] and contemplate what's actually happening to that thin ribbon of metal being removed. Most of the lathe's motor power is being turned into heat by internal friction in the chip being removed in the zone around the cutting edge, and surface friction at, and immediately behind the cutting edge, near-instantly heating the chip by up to several hundred degrees. Reducing the surface friction using a suitable cutting oil reduces the strain on the machine as a whole, and reduces workpiece and tool heating (and thus expansion) with consequent improvements in maximum usable feed and depth of cut, surface finish and accuracy. It also drastically increases the life of the cutting edge.<br />
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=== Practicalities === <br />
We don't have a coolant system for the lathe and *really* don't want the maintenance hassles of using soluble cutting oil/coolant as if used infrequently its a PITA to keep recirculated high water content cutting fluids from going rancid and stinky, and they can also rust the ways, so even a total loss gravity feed system is problematic. Therefore if dry machining doesn't give a good enough finish, we tend to use oil applied topically, by hand to the work. <br />
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* Hard brass is typically free-turning without oil, however some light oil for the final cut can improve surface finish, but with the disadvantage that it will increase loose chip buildup on the tool as hard brass typically forms short spalls or splinters rather than curly chips.<br />
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* Many Aluminium alloys tend to be gummy, and Paraffin or other mineral spirits mixed with a little oil can help prevent the aluminum welding to the tool edge. WD40 will do at a pinch, but its messy to apply from a spray can.<br />
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* Steel really needs *GOOD* cutting oil. Lard oil is the traditional choice for steel. If there are any objections to lard oil, we should bite the bullet and get some commercial dark high Sulphur cutting oil, but beware, many such oils use an additive package that includes lard oil.<br />
* Cast iron (except ductile) should be cut dry, as the carbon micro-inclusions self-lubricate it, and the carbide in the dust (primarily Cementite) are very abrasive, so tend to form a grinding compound if mixed with oil. <br />
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I've sorted out an oil pot lid with a 1/2" brass collar soldered in to give a nice smooth sided hole, for ease of use and to minimize the risk of spills when using a brush to apply cutting oils, and got some dirt-cheap brushes. It fits Shippam's paste (and similar own-brand spread) jars and I've found several jars and ordinary lids to seal them for storage. Unfortunately it isn't the easiest to get this type of jars' lids back on square so they seal properly, and if you over-tighten them and there's a temperature change, they can be a total <expletive> to reopen. Using the rubberised handles of a large pair of pliers to grip the jar lid just above its rim is the best option, and avoids damaging the lids.<br />
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''N.B. For the smaller brushes, the glue holding the bristles in is attacked by paraffin. To prevent loss of bristles, crimp the aluminium ferrule of each new brush of this type before use.''<br />
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We have, in labelled jars:<br />
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* Sulphurised Lard oil thinned with paraffin. Best choice for heavy cuts and threading in steel but stinky.<br />
* Lard oil thinned with paraffin. Good for steel and acceptable for softer copper alloys<br />
* Paraffin with a trace of light oil. Good for aluminium, and can help prevent squealing chatter on finish cuts in brass.<br />
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I've also got some paraffin wax (in the form of a stubby candle), which can be applied lightly (under power) to brass and aluminium stock especially on the finish pass. It makes less mess than oil but unfortunately tends to build up on the tool tip, making it difficult to 'work by eye' without frequent pauses to clean the tool tip.<br />
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We've also got a tin of [https://www.rocol.com/products/rtd-compound Rocol RTD cutting compound], which is a thick paste. Its highly recommended for drilling and tapping steel (in the drill press or by hand), but as a paste, is less useful for general lathe work unless thinned to a fluid consistency, e.g. with paraffin or white spirits. OTOH its certainly worth trying for high speed facing steel as it is less likely to get flung off.<br />
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== Cleaning and Maintenance ==<br />
Swarf is a significant cut hazard to the operator, especially stringy swarf from cutting steel. Never touch it bare-handed - always use a tool e.g. a brush, or a hook, or needle nose pliers for grabbing long swarf.<br />
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* After use, brush all swarf off the toolholder, compound and cross slide etc. ways and leadscrew. Ian B has blocked off the opening at the headstock end of the rear splashguard (to try to keep swarf out of the motor), so one must sweep the swarf towards the open tailstock end and catch it in a dustpan or similar. Preferably, also thoroughly clean out the chip tray under the lathe, but at least sweep out visible swarf.<br />
* Wipe up any cutting fluid residue and re-lubricate affected sliding surfaces with way oil.<br />
* Do not solvent clean the chuck guard, as it will make the plastic brittle, or even craze it. Water with a little detergent is permissible for cleaning it, with the guard totally removed from the lathe.<br />
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Before engaging the half-nuts for power feed/threading, check the leadscrew is clean! ''Best cleaned under power, with a toothbrush.'' <br />
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'''Caution:''' The traverse gears behind the carriage handwheel are in an open-backed housing and tend to become packed with swarf! Swarf buildup here will result in jerky carriage movement. Clean out as much as you can with a toothbrush ...<br />
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===Lack of lubrication and/or swarf or dirt build-up can be disastrous===<br />
* If using the change gears/power feed, lack of lubrication of the B-C stub shaft center pin or either leadscrew end bearing can result in seizure and immediate destruction of one or more gears in the gear train or worse. <br />
* Small pieces of swarf can get between the saddle and ways, or into the slides degrading accuracy, possibly permanently if hard swarf scores them, or jamming them. The carriage handwheel gears behind the apron are notorious for accumulating swarf, and swarf buildup on the leadscrew can prevent the half-nuts engaging properly, resulting in scrapped work, and possibly stripped half-nuts. <br />
* Metal swarf can get into the motor (''though Ian B has modified the rear chip catcher to reduce the risk)'' or into the control box via the leadscrew, and short-circuit stuff. At best it will blow the fuse and need a strip-down to clean it out, at worst it may require a replacement [https://www.amadeal.co.uk/acatalog/Speed-Control-Circuit-Board--12amp-AMA_SP_CJ18_SCB12.html#SID=12 speed controller] ''(currently £96)'' and/or [https://www.amadeal.co.uk/acatalog/550W-motor-for-CJ18A-Mini-Lathe-467.html#SID=240 motor] ''(currently £105)'' and possibly other electrical parts. We should probably fit a [https://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C3-Mini-Lathe-Spares/C3-256-Leadscrew-Grommet-Dustproof-Cover C3-256 Leadscrew Grommet] to keep swarf out of the control box, as it tends to drop onto the 'Filter' board which is mounted horizontally, below the leadscrew.<br />
* Grit from grinding, sanding etc. forms a grinding paste with the way oil, and will rapidly wear out the ways, saddle and slides. Keep grit off at all costs e.g. by covering the ways and slides during grinding/sanding operations, and if there's any chance grit has gotten where it shouldn't, clean and re-lubricate *BEFORE* moving the carriage or slides, then move the carriage and slides, wipe down where they were with a clean paper towel and check there's no remaining traces of dirt other than clean way oil on the paper towel. If it doesn't come clean when you re-lubricate and move it again, a full strip down may be required to solvent clean and relubricate the precision sliding surfaces.<br />
* Although a metalworking lathe *can* be used to turn hardwood, wood dust and small chips are extremely pernicious, as they get everywhere, even clinging to clean surfaces, are abrasive due to their silica content, and are hygroscopic, promoting rust. An even more thorough clean-up than after using abrasives is needed, immediately afterwards. Oily wood dust and fine wood chips in significant quantities are a fire hazard, even in the trash bin.<br />
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===Lubrication===<br />
See section: "Lubrication" in LittleMachineShop.com "Mini Lathe User’s Guide" [[Ian_M's_Lathe_Notes#Manuals|(below)]]. As we usually only open two nights a week, in the table on page 16, Daily lubrication becomes Weekly and Weekly becomes Monthly.<br />
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===General Maintenance===<br />
* The grubscrews holding the cross-slide and compound slide dials tend to loosen due to vibration and use of the dials. Keep them snugged up, but not so tight the dials cant be set without an Allen key.<br />
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* The screws holding the cross-slide nut tend to work loose due to vibration. Crank the handle to and fro through the backlash and visually check there is no movement of the screw heads in their holes. If there is, see the [[#Excessive_cross-slide_backlash|notes below]].<br />
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===Removing the Carriage===<br />
Its possible to remove the carriage from the bed for cleaning etc. without dismantling it. The only stop to its motion is the righthand leadscrew bearing.<br />
<br />
Start by removing the tailstock. Crank the carriage to the tailstock end then remove the leadscrew bearing (two screws and a nyloc nut on the leadscrew end). With the half-nuts open, hold the leadscrew centered in them and crank the carriage off the end of its rack, then slide it off the end of the bed.<br />
<br />
Refitting is the reverse of removal, except (if its gibs are correctly adjusted) the carriage will be very tight on the end of the bed ways so may be difficult to work onto the ways without a stack of blocks of wood or similar to support it at exactly the right height. The righthand leadscrew bearing must be refitted with the carriage as close as possible to it and the half-nuts firmly closed to support the leadscrew at the correct height to hold it in alignment while the screws are being tightened. The nyloc nut controls leadscrew end-play. Fully tighten it then back it off slightly till the leadscrew turns freely with its change gear removed.<br />
<br />
If the Apron has been off, refit it with the screws no more than lightly finger tight and only finally tighten them after checking lead screw engagement at both ends of the carriage travel and that the rack and pinion operates smoothly over the full travel.<br />
<br />
== Issues and Annoyances ==<br />
As of September 2023 - mostly resolved, apart from the spindle bearings and runout, the lathe is in better condition than it has been for a number of years.<br />
<br />
===Four Jaw Chuck has two jaws too tight===<br />
Fixed 27/10/2023: Two of the chuck jaws were tight in their slots, making precise adjustment difficult due to lack of 'feel'. Moving the jaws round the slots showed the problem mostly followed the jaw not the slot. The grooves in the opposite sides of the affected jaws that run in the chuck slots were slightly out of true, and the rails either side of the slots were slightly too thick towards the center. Due to the difficulty of seeing the high spots, after cleaning up and deburring the jaws didn't do enough to ease them, I decided to grind the top of the rails where they were binding. Several repetitions of spotting with Engineer's blue, grinding, then diamond filing the high spots has eased them enough. I cleaned everything, greased the jaw slides and screws, and refitted the studs so the chuck is now fit for service.<br />
<br />
''N.B. Don't move the jaws to a different slot - the formerly tight jaws *must* stay in the slots furthest from the makers mark.''<br />
<br />
===Excessive Runout===<br />
Mostly fixed 24/10/2022: I ground the chuck seating surface of the spindle nose (outside lip) to under half a thou runout. This also cleaned up several burrs. It would be possible to do better, but that would need good spindle bearings, and a more rigid toolpost grinder mount.<br />
<br />
Our spindle nose was damaged years ago by a person with little mechanical aptitude (who shall remain nameless) beating it up with a hammer mushrooming the spindle nose. We are getting several thousandths runout at the end of the MT3 bore, a MT3 to MT2 reducer sleeve in it runs visibly out of true, as does the spindle nose flange. When you put a chuck on it, the runout is magnified by the distance from the spindle nose. Ideally we would replace the spindle when we change the bearings but its £52 [https://www.amadeal.co.uk/acatalog/4-Spindle-Upgrade-Real-Bull-Mini-lathe-CJ18-series-AMA_SP_CJ18_003RB.html#SID=9 from Amadeal] and money is tight. It may well require more work after the bearing upgrade. Once good bearings are in, if we can borrow a decent MT3 arbour as a reference, we should consider skimming the bore.<br />
<br />
===Spindle bearings===<br />
* The spindle bearings appear to be close to worn out. They are notably noisy when running, and there appears to be more slop in the spindle than is desirable. We have some ideas for possible replacement/upgrade, but it requires a major teardown.<br />
<br />
: The original bearings are allegedly 6206-2RS or 6206-ZZ deep groove ball bearings - 2RS codes rubber seals both sides and ZZ codes metal shields. Although the deep groove gives reasonable ability to withstand axial loads, the bearing balls point contact means they are vulnerable to [https://en.wikipedia.org/wiki/Brinelling brinelling] due to shock loading. The jammed on three jaw chuck didn't help this, as before we skimmed the spindle nose lip, it had to be driven off using a bar through the spindle bore, shock loading the bearings every time. Also even a minor 'crash' could have brinelled them due to eccentric shock loading, and the lathe has previously been crashed badly enough to need drive gear replacement. There are also issues with the 'approved' method of spindle and bearing removal from the headstock brinelling them, even if you don't abuse the spindle nose with a hammer!<br />
<br />
: A possible replacement is 30206 tapered roller bearings. The new bearings are slightly thicker so the plastic spindle spacer (15) needs to be machined to length to get the 45 tooth spur gear that drives the change gears laterally aligned with the tumbler gears. If a temporary replacement (3D printed?) is fitted, the lathe can be run (without power feed capability) so this can be done on the lathe after fitting the new bearings. As tapered roller bearings have line contact, they are significantly more resistant to brinelling.<br />
<br />
: ''See [[Talk:Ian_M%27s_Lathe_Notes]] for notes, links etc. for this upgrade.''<br />
<br />
===Motor stuttering===<br />
* Fixed 21/09/2023: The motor was running very erratically and it was very difficult to set a speed. Several loose connections were found in the control box, mostly loose female spades to the motor controller board, but also a dry jointed braking resistor on the 'Filter' board, and an inhibit wire completely off its terminal on the forward/reverse switch, making intermittent contact. After tightening and/or remaking all affected connections, it was much improved but still not right below 300 RPM. The remaining issues were due to poor wiper contact in the speed control pot, and stripping it, cleaning the track and contact ring and re-tensioning the contacts resulted in the motor now running smoothly over the full speed range. The speed is slow to settle, and while part of that is probably the lag in the digital tach, I suspect that the KBIC motor speed controller isn't properly tuned as it was (allegedly) previously replaced.<br />
<br />
===Drive belt slipping===<br />
* Fixed 28/9/2022: During testing the motor after the above issue, it was noted that the chuck could be stalled, slipping the drive belt, with not much torque. The drive belt was determined to be loose and a bit worn, but still in acceptable condition. <br />
<br />
: Access for servicing the belt requires removing the control box ''(2 spades to ZVR switch disconnect the supply, speed sensor and motor simply unplug from the 'filter board')'', the motor cover, chuck guard switch assembly + wiring cover, the change gear 'A' (drive) shaft carrier assembly, and the tumbler gear assembly. See https://youtu.be/EkxlIz01BdA for disassembly/reassembly, though on our lathe, the speed encoder ring on the spindle prevents the belt cover from being fully removed without disturbing the spindle nuts. There is enough room to work with it loose, but still trapped by the encoder ring. Also, unlike the video, if the 'jack' screws under the headstock are correctly adjusted, and the studs aren't excessively bent, there is no need to make custom studs. <br />
<br />
: It turns out that our lathe was missing the M6 hex headed jack screws that press the motor down to resist the belt tension, and the motor had cocked out of position at a severe angle. I know Ian B had had considerable trouble adjusting it after the motor fault back in October 2022, and I believe it had been getting slowly worse ever since. The jack screws were probably mistaken for headstock fixing bolts during disassembly after the crash that resulted in the metal Hi/Lo gears being fitted, then lost. The penny washers on the studs had dished, so I turned them over and backed them up with smaller washers and switched to Nyloc nuts so they cant back off due to vibration. N.B. There is a packing washer on the motor side on one of the studs, presumably so the shaft is true to the ways. Adjusting the motor is awkward to say the least. One has to slack the stud nuts off a lot, pry under its rear end to lift it enough to be parallel to the ways, snug the stud nuts, check alignment, then set the jack screws and their lock nuts to hold it there, and finally tighten the stud nuts. <br />
<br />
: Tension: According to Sieg, it should be possible to twist the belt 90° mid span with a light finger grip. Other sources say 1/32" - 3/32" deflection mid span with light finger pressure.<br />
<br />
===Speed display blanking===<br />
* The speed display has been intermittent, blanking and flashing 8888 and 0 at certain speeds for as long as I have been using the lathe. Finally on 18/07/2022 it failed completely, with no display. I removed the display module and bench tested it - the pins are labelled 5V GND PL PE, PE is frame ground and PL is a TTL level pulse from the speed sensor - confirming that it was in good working order. My suspicions then turned to its power supply on the 'Filter' board. With both the sensor and display unplugged, the 5V rail was found to have a only a couple of volts, but the unreg DC was 17V and stable. Replacing the 78L05 5V regulator restored the 5V rail and normal operation.<br />
<br />
: ''I conclude its been failing for a while with high load current due to speeds with more lit segments causing it to drop out, resetting the speed display, causing it to blank, lowering the current enough for the regulator to recover, then the display MCU lamp tests (8888) then re-acquires the speed, repeating ad-nauseum till the speed is changed. I don't like the design as the high input voltage results in excessive dissipation.'' <br />
<br />
: ''ToDo: If it fails again, bench test display to measure its worst case current consumption, then fit an appropriate dropper resistor to reduce the 78L05 dissipation.''<br />
<br />
===Quill spinning when drilling===<br />
* The quill was tending to spin while drilling because its anti-rotation pin (a M5 dog tip setscrew) was sheered. I've removed the debris, aligned the scale with the top of the tailstock and fitted a longer M5 dog-tip setscrew to replace it, with a nut to lock it at the correct height. N.B. the pin isn't that 'meaty' so if using big drills in tough metals, to prevent shearing it, it should be backed out so the quill can be turned by hand and unwanted rotation controlled by being quick with the quill lock if it starts to spin, or even using a close fitting rod in one of the chuck key holes with plastic tube over it to protect the ways. <br />
: ''If the screw sheers again, the quill will need to be removed and the tailstock taken off the lathe so the sheered tip can be shaken out, and if the setscrew is difficult to remove it probably means the threads are mangled where it sheered. Try driving it right through with the quill out.''<br />
<br />
===Sloppy quick change toolpost locking mechanism===<br />
* Once the dovetail clamp screw was slackened, there was nothing preventing the dovetail twisting or cocking significantly, and friction with the toolholder made it tend to do so, making toolholder insertion and removal more difficult unless the clamping screw was backed off excessively. I added a compression spring around the clamp screw inside the toolpost to push the dovetail outwards so it mostly retains alignment when open, allowing toolholders to slide on or off cleanly with far less screw slackening.<br />
<br />
===Leadscrew rubbing===<br />
* The leadscrew shaft is rubbing on the insulating separator inside the control box. Unfortunately the corner of the relay on the Filter Control Board (#160) doesn't allow enough clearance. Although the friction isn't much of a problem at high reduction ratios, e.g. 16:1 power feed, it increases the stress on the change gear train, and may be problematic when threading at feeds above 1:1. ''Possibly pack out the control box mountings by a couple of mm.'' <br />
<br />
===High/Low lever backwards!===<br />
* The high-low drive gear selector behind the headstock is incorrectly labelled and differs from the manual: low gear (which we normally use) is with the lever towards the tailstock. ''I suspect that the gears in the headstock were refitted the wrong way round when it was upgraded to metal gears.''<br />
<br />
: ''ToDo: Get it reassembled the right way round during the spindle bearing upgrade!''<br />
<br />
===Carriage lock fouls top slide===<br />
* The T handscrew has been replaced with a M5 hex headed bolt, to permit access when the top slide is over it. An 1/4" drive 8mm socket is usually left on it, but needs to be removed when the full cross slide travel is needed. The small (4 jaw) chuck key is near enough 1/4" to use for it. If you need to (un)lock it while the compound is over it, you'll need an 8mm spanner. ''The [https://www.amadeal.co.uk/acatalog/Mini-Lathe-Carriage-Lock-463.html Amadeal lock screw] is in the spares tin as it was too high and fouled the compound slide.''<br />
<br />
===Tailstock locking lever loose===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock - See full image for key to screws]]<br />
* Diagnosed and fixed 10/1/2023 - In the base of the upper section of the tailstock, there are two dog tip set screws that engage with locating grooves in the counter-rotating shafts carrying the eccentric locking cams. They'd backed off, probably due to vibration. They need to be tightened till they bottom out in the groove, making sure they are '''in''' the groove, backed off half a turn so the shafts can turn easily, and locked in place. There's no facility to do so, so reassemble with weak threadlocker. Unfortunately to get to them you have to remove the tailstock base slide, which is held on by the pressure of four adjusting grub screws, which all need backing off, and one socket headed bolt from underneath so full tailstock realignment is required after reassembly, which even for a rough alignment is tedious.<br />
: <s>The tailstock locking lever is loose and can be pulled out on its axis. It works OK when fully pushed home but needs investigating. ''I tightened the grub screw as the lever was coming off its shaft, but the whole shaft pushes/pulls in and out. It works OK fully pushed in, but it seems something that is meant to retain it has failed inside the tailstock base.</s><br />
<br />
===Gear alignment issues===<br />
* Change gear alignment is poor. I've currently got a gapped washer (to clear the key) packing out the A shaft so the gears line up, but this reduces the key's engagement so is problematic due to the high loading if the gears are set up for coarser threads. <s>Also I need to turn down some penny washers to slightly less than the root diameter of the metal 20T pinions, as gear retaining washers.</s> ''The gear retaining washers for A gear and B-C stub shaft are now done, turned down to slightly under 16 mm dia. Spares in the change gear tin. ToDo: The D (leadscrew) washer requires a larger center hole, so make two more with that hole.'' <br />
<br />
===Saddle gibs loose===<br />
* Fixed 11/04/2023: I took the apron off for access (and to clean the carriage handwheel gears), and found the front sheer plate screws were completely loose. I've snugged them up some and set the opposing grub screws and got a lot of the slop out. I've re-checked the front ones, and taken up the slop in the rear ones - Unfortunately it wasn't possible to get carriage movement to have an even 'feel' over its whole travel, and its noticeably tighter near the tailstock. If light hand pressure on the side of the unlocked carriage can cause movement (with the half-nuts open), its time to readjust them again, though it should be possible to move the carriage with a firm push. <s>The saddle gibs (actually the sheer plates) were too loose, to the point that engaging a slightly stiff threading dial could cause it to self-feed, an obvious crash hazard if working near the chuck or a step in the work.</s><br />
<br />
''N.B. the lefthand front opposing grubscrew is short, (fully recessed) and unlike the others does *NOT* have a locking nut as it must clear the traverse pinion. A wrap of PTFE tape provides enough friction to keep it in place, though possibly a bit of nylon fishing line down its hole would be better.''<br />
<br />
===Excessive cross-slide backlash===<br />
* ''Fixed 21/11/2023.'' Originally, back in October 2023, The cross-slide screw had excessive backlash (nearly three turns), which increases the risk of loosing track of the cut depth when cutting steps, and during threading operations. If you ended up off by a turn too far in, a crash would be the most likely outcome.<br />
: The original excessive backlash was traced to loose cross-slide screw nut mountings. The nut has two socket headed cap screws pulling up, one either end, accessible from the top of the cross-slide, which control the tilt of the nut to take up backlash in the nut, and an opposing grub screw pressing down on the center of the nut to make it longitudinally rigid. Snugging up the grub screw reduced the backlash to 10 divisions or so, or 0.25 mm. A year later, the backlash had increased to one turn due to the cross-slide nut mounting screws working loose again.<br />
<br />
: 07/11/2023: I investigated further: It is difficult to get the cross-slide nut aligned correctly as it must be at the same height as the screw which is constrained by the bearing surfaces in the bracket. With the cross-slide almost at the front limit of its travel, I removed the screw and set the nut as level as possible and visually centered in the bore, then re-fitted the bracket and screw, then adjusted the tilt till it turned freely through the backlash. I then tilted it up at the front till some drag was felt to minimise the backlash and tightened the screws to lock it in place balancing them to maintain the same feel as I tightened them. The result was 7 divisions of backlash, acceptable but not great. During normal turning operations, the load on the nut is tension on the front screw and pressure on the grubscrew, so if it slackens again due to vibration from chatter, odds are it will be the rear screw that's loosened.<br />
<br />
: 16/11/2023 - 21/11/2023: The backlash had crept back up to 11 divisions (0.275 mm). We don't have any >14 mm brass stock (or even near that) so I tried making the shim washer out of aluminium. I was shooting for 0.24 mm but due to poor technique got 0.28 mm. No good - locked solid. I lapped it down and tried it till I got it down to 0.20 mm which gave about 3 divisions backlash - good enough, but the screw was too tight due to the shim washer not being bevelled at its outer edge resulting in it cupping in its seat. Filing a bevel round the OD and re-lapping it resulted in a 3 - 4 divisions of backlash. Its a little mushy due to the washer having been kinked removing it, so ideally a new (brass) washer should be made. <br />
<br />
* Further reduction of backlash: https://youtu.be/Wu_tI29JL2Y?t=163 <br />
: Brass tinned with Pb-free solder to form a white metal bearing surface should work at least as well as the bronze used in the video. The shim washer needs to be 10.2mm ID, with a full thickness bevel on a 14 mm OD. It isn't necessary to remove the lead screw from the cross slide, as the washer can be fitted in-situ with only the bracket removed.<br />
<br />
===3 Jaw chuck didn't mount properly===<br />
* Fixed 7/4/2023 by grinding the spindle nose lip. The three jaw chuck can now be installed and removed by hand with no hammering. A test bar in it now has only 2 thou runout (TIR) at the chuck.<br />
: <s>The three jaw chuck and the faceplate aren't seating properly on the spindle nose. Its too tight on the register diameter of the lip. This results in grossly excessive runout, and also makes this chuck and the faceplate a PITA to fit or remove.</s><br />
: ''The spindle nose had been abused with a hammer (before my time) which mushroomed it and may have brinelled its bearings. See '''Excessive Runout''' and '''Spindle bearings''' above.''<br />
<br />
== Manuals, Books and other resources ==<br />
=== Manuals ===<br />
The [https://wiki.richmondmakerlabs.uk/images/a/a3/Lathe_InductionNotes.pdf RML CJ18A Mini-Lathe Induction Notes]. Your mandatory Lathe Induction will cover most of this but its good to be able to refer back to it.<br />
<br />
Official [https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Amadeal CJ18A Manual], or paper copy (less complete) kept on shelf above lathe.<br />
<br />
The [https://www.chesterhobbystore.com/wp-content/uploads/2022/11/Conquest-Super-Lathe.pdf Conquest Super Lathe manual] is considerably better than the Amadeal manual and is for a near-identical machine.<br />
<br />
The [https://littlemachineshop.com/images/gallery/info/minilatheusersguide.pdf Mini Lathe User’s Guide] from LittleMachineShop.com is even more comprehensive, going into its usage in some detail, with a proper TOC, and covers both US and Metric versions of Realbull Mini-lathes. ''The only fly in the ointment is the threading section assumes a US lead screw so change gear selections and threading dial divisions will not be correct for our lathe.''<br />
<br />
[https://www.arceurotrade.co.uk/machineguides/C3-Mini-Lathe-Dismantling-and-Reassembly-Guide.pdf Sieg C3 Mini-lathe Dismantling and Reassembly Guide] "A picture story book to help you dismantle and reassemble your Sieg C3 Mini-Lathe" ''It is similar enough to ours to serve as a maintenance guide, except for the electronics, spindle drive and other headstock innards.<br />
<br />
The motor controller is a clone of a [https://acim.nidec.com/drives/kbelectronics/-/media/kbelectronics/documents/dc-drives/manuals/kbic_manual.ashx?la=en KBIC® SCR DC Motor Speed Control]<br />
<br />
=== Books ===<br />
'''Metal Turning on the Lathe''', by David A Clark, Crowood Metalworking Guides, ISBN-13: 978-1847975232 [https://www.amazon.co.uk/gp/product/B00E78RKIG Kindle Edition (£8.99)]. ''A 'free' epub can be googled for, *NOT* linked here due to dubious legality.''<br />
<br />
'''[https://archive.org/details/03screwcuttinginthelathe Screwcutting In The Lathe]''', by Martin Cleeve (a pen-name of Kenneth C Hart), Workshop Practice series #3, ISBN-13: 9780852428382<br />
<br />
'''[https://archive.org/details/15workholdinginthelathe Workholding in the Lathe]''', by 'Tubal Cain' (a pen-name of Tom Walsh), Workshop Practice series #15, Argus Books, ISBN-10: 0852429088<br />
<br />
'''[https://archive.org/details/20metalworkandmachininghintsandtips Metalwork and Machining Hints and Tips]''', by Ian Bradley, Workshop Practice series #20, ISBN-13: 9780852429471<br />
<br />
'''[https://archive.org/details/38toolandcuttersharpening Tool and Cutter Sharpening]''', by Harold Hall, Workshop Practice series #38, ISBN-13: 9781854862419<br />
<br />
'''[https://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpaperT204.pdf Cutting Fluids]''', by EC Bingham, NIST Tech. Paper No. 204, 1921<br />
<br />
=== WWW resources ===<br />
==== Mini-lathe Specific ====<br />
There's a *LOT* of mini-lathe info online. Notable sites include:<br />
* http://www.mini-lathe.com/ - A major Realbull/Sieg mini-lathe resource.<br />
* http://mikesworkshop.weebly.com/lathe-modifications.html - many mods including carriage DRO autostop, and variable speed leadscrew motor drive, cross-slide motor drive, etc. He also has a page with a bunch of accessories, toolholders etc. - http://mikesworkshop.weebly.com/lathe-accessories-and-tooling.html<br />
* http://andysmachines.weebly.com/variable-speed-controls.html - Scroll down to the 'UPDATE' section for the schematic of a very similar SCR speed control board. It also has the schematic for an earlier version of the Auxiliary Control Board (aka: 'Filter' board).<br />
<br />
==== Forums ====<br />
''with publicly accessible archives''<br />
* https://groups.io/g/7x12MiniLathe - Mini-lathe specific, active<br />
* https://www.hobby-machinist.com/forums/mini-lathe-mini-mill-information.220/ - active<br />
==== Youtube Playlists & Videos ====<br />
* Blondihacks: [https://www.youtube.com/playlist?list=PLY67-4BrEae9Ad91LPRIhcLJM9fO-HJyN Lathe Skills] (playlist) - "This is an educational series to help you learn to use your metal lathe. Watch them in order for best results! Satisfaction not guaranteed, especially if you're a cranky sort of person."<br />
* Frank Hoose (Minilathe.com) has a couple of relevant Youtube playlists:<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn7ON0jGM5UbM-KZDT56MOIp Mini Lathe Operations]<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn4nGRZaVq3wTOlvZNOmdAZ2 Mini Lathe Overview]<br />
<br />
==== General Machining ====<br />
* https://www.machiningdoctor.com/ - "THE #1 MACHINING TECHNICAL HUB"<br />
<br />
==Projects==<br />
[[File:VESA mount.jpg|thumb|Machined VESA mounting plate (left) and plate from Dell monitor stand it must match (right). The translucent washer shows the size of the original center hole.]]<br />
* My first faceplate project was boring out the center hole in a VESA mounting plate to adapt it to fit onto a surplus Dell 1708FP monitor stand. The part was centered using the tailstock dead center engaging with its original center hole. I clamped the part with studs and penny washers on the driving side of two opposite corners, with cap screws in the next slot round to trap the corners under the clamping washers, then withdrew the tailstock and dead center. After machining out the bore, I used the tip of the tool, rotating the chuck by hand, to scribe a circle for laying out the bolt holes. I finished off laying out and drilling the bolt and locating holes by hand at home, fitted it to the stand, and mounted the 2nd hand LG 24" widescreen monitor.<br />
<br />
* Another ultimately unsuccessful project was fly cutting aluminum flat bar to thickness to make custom shims for the set of carbide insert tools, for the four way toolpost. The 8 mm shank tools need ~2.5 mm shim stacks, and the 6 mm shank tools need ~4.5 mm shim stacks. Ideally I'd machine single shims, but the only stock I've got handy cleans up to only 3.2mm, and some fine shimming may be needed to fine-tune the tool height.<br />
<br />
: After sorting out the clamps so they were no longer twisting the aluminum flat bar stock, and switching to the short 45° turning SCMT06204 insert tool in the four way toolpost, to improve rigidity and get a well controlled tip radius, the finish was much improved. I'm still having problems getting an even thickness and am getting approx. 0.05mm variation, I suspect due to the aluminium bar stock distorting due to internal stresses as its surface is cut away. ''ToDo: try supergluing the stock to the faceplate before clamping to further reduce chatter and stop the warping.''<br />
: Looking back on this project a year later, its fairly obvious that the thickness variation was probably due to faceplate surface runout due to the damaged spindle nose.<br />
<br />
* Raphael has been working on a steel rocket nozzle with some assistance from myself. We have set up the rough cut chunk of ~ 50mm steel bar, faced both ends (to 50mm length) and turned the OD to 49mm to clean it up. Its going to need through drilling, probably some boring, and quite a bit of detail work on the OD. It will then need to be transferred to a jig in the drill press vice to allow a pattern of angled traverse holes to be drilled with acceptable accuracy.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_Lathe_Notes&diff=17590Ian M's Lathe Notes2023-11-23T10:30:58Z<p>IanM: /* Excessive cross-slide backlash */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br />
<br />
''Currently these notes are semi-organized and non-authoritative. As I become more experienced with the RML CJ18A mini-lathe, I'm cleaning up, extending and reorganising them. Some lathe operating experience is assumed. If in doubt, '''*ASK*''' me, Andy H<sup>*</sup> , Jonathan H or another experienced minilathe operator!<br />
<br />
''* Andy H should be asked (for an authoritative answer) any questions involving RML usage policies or acquiring tooling or materials through RML.''<br />
<br />
== The Lathe ==<br />
Our Facilities page [[Facilities#Lathe|has]]:<br />
<blockquote><br />
'''Lathe'''<br />
[[File: Lathe2.jpg |200px|right | Lathe]]<br />
In the kitchen. <br />
<br />
Marked as a CJ18A Mini-Lathe from [[https://www.amadeal.co.uk/acatalog/CJ18A-Mini-Lathe-7x14-Machine-100mm-3jaw-Metric-With-Metal-Gears-AMA_LA_CJ18_M_3_MGRB.html Amadeal]]<br />
[[https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Manual]] <br />
<br />
[[Media:Lathe InductionNotes.pdf| Induction Document]]<br />
<br />
Possible upgrades:<br />
*https://www.youtube.com/watch?v=GwT-JQLbNPA<br />
<br />
''Please do not use the lathe until you have received induction'' <br />
<br clear=all><br />
</blockquote><br />
Its a Chinese import 7x14 mini-lathe. The 7x14 refers to the maximum diameter and length of work, in inches and is only a theoretical measure of the working envelope as you loose length to the chuck + any tailstock tooling, and the diameter is over the bed, not the cross-slide. See actual specifications below. <br />
<br />
Most if not all Chinese 7x10 to 7x16 mini-lathes seem to be remarkably similar (not uncommon with Chinese products due to [https://www.bunniestudios.com/blog/?p=284 Shanzhai (山寨)] )<br />
and the OEM of our Amadeal CJ18A Mini-Lathe was probably [https://www.made-in-china.com/showroom/cheap-lathe Yangzhou Realbull Machinery Co. Ltd]. Very similar lathes are also made by [https://www.siegind.com/lathe-machine.html Sieg], but their lathes tend to be slightly less sophisticated than the equivalent Realbull models.<br />
<br />
''N.B. Many Sieg parts are known to have slight but critical differences from Realbull parts, so '''DON'T''' order Sieg spares for a Realbull lathe!<br />
<br />
== Key Specifications ==<br />
Amadeal says the CJ18A Mini-Lathe is a 7x14 model with:<br />
<blockquote><br />
* Power 550 W<br />
* Distance between centres : 350 mm<br />
* Swing Over Bed: 180 mm<br />
* Swing Over Cross Slide: 110 mm<br />
* Taper: MT3<br />
* Tailstock Taper: MT2<br />
* Chuck diameter: 100 mm<br />
* Spindle Speed: 50 - 2500 rpm ''(with digital readout)''<br />
* Spindle Bore: 20 mm<br />
* Cross slide Travel: 65 mm<br />
* Range of Metric Threads: 0.5 - 2.5mm.<br />
</blockquote><br />
* The lead screw is metric, pitch 1.5 mm.<br />
* The spindle center is 90.6 mm above the flat of the bed (measured).<br />
<br />
Even though the compound and cross slide handwheels appear to be calibrated in thousandths of an inch, as ours is a metric machine, they only approximate that. One turn of a slide handwheel is 1mm advance, and they have 40 divisions, so each division is 0.025 mm, (approx. 0.984 [https://en.wikipedia.org/wiki/Thousandth_of_an_inch thou]). Similarly, the tailstock quill advances 1.25 mm per handwheel turn, which has 50 division dial, giving the same 0.025 mm divisions, but only 4 turns per 5 mm. The carriage handwheel is awkward - it moves approx. 19.2 mm per turn, and doesn't have a dial scale.<br />
<br />
== Notable Accessories ==<br />
We have:<br />
* [https://www.amadeal.co.uk/acatalog/160mm-Face-Plate-for-the-4-Mini-lathe-AMA_AC_CJ18A_FP160RB.html#SID=129 160 mm (6 1/4") Faceplate]<br />
* 100 mm (4") three jaw self-centering chuck (OEM standard) 22.5mm bore, with inside and outside jaw sets<br />
* 100 mm (4") four jaw (independent) chuck with reversible jaws (8 TPI screws)<br />
* Tailstock drill chuck (max. 13 mm dia.)<br />
* Live center for tailstock (+ OEM fixed center) <br />
* Four way Tool Post (OEM Standard)<br />
* [https://www.amadeal.co.uk/acatalog/Quick_Change_Tool_Post_for_the_mini-lathe.html Quick Change Tool Post] + 3 tool holders<br />
* [https://www.amadeal.co.uk/acatalog/Fixed-Steady-for-Mini-Lathes-AMA_AC_CJ18A_FSRB.html#SID=145 Fixed Steady Rest]<br />
* [https://www.amadeal.co.uk/acatalog/Travelling-Rest-for-Mini-Lathes-AMA_AC_CJ18_TSRB.html#SID=144 Travelling Steady Rest]<br />
<br />
''You'll find all of the above on the shelf above the lathe, with the accessories in the wooden box, apart from the steadies, which live next to it. Change gears, spare parts, and most cutting tool tips/blanks are in labelled white rectangular tins behind the lathe.''<br />
=== Measuring Tools ===<br />
We have:<br />
* Various dial indicators - the one with the adjustable magnetic base stand is the most convenient for most lathe setup work.<br />
* 25mm micrometer (in little grey case)<br />
* Grey case containing set of measurement tools including dial calipers, micrometer, steel rule (metric & inch), engineers square, and a fish-tail gauge<br />
<br />
''We currently lack''<br />
* ''A tool height setting gauge''<br />
<br />
=== Hand Tools ===<br />
Some common tools needed for normal use are kept with the lathe, in or attached to the wooden accessories box:<br />
* 2 mm Allen key - adjusting cross-slide and compound gibs<br />
* 4 mm Allen key - quick change toolholder tool clamping screws + height adjust, tightening dials<br />
* 5 mm Allen key - four way toolpost tool clamping screws, engaging/disengaging threading indicator<br />
* 6 mm Allen key - locking/unlocking quick change toolholder<br />
* 8 mm spanner - locking carriage when 8 mm socket can't be used, locking gib adjuster nuts <br />
* 13 mm spanner - changing chucks, locking steady rest jaws<br />
* Very long needle nose pliers - for grabbing swarf safely, holding one end of emery cloth safely so you can keep your fingers away from the jaws, and extricating small objects from awkward places.<br />
<br />
== Change Gears ==<br />
[[File:BC puller 1.jpg|thumb|Custom puller for B-C stub shaft]] [[File:BC puller 2.jpg|thumb|Pulling the B-C stub shaft]]<br />
See "Conquest Super Lathe" manual ([[#Manuals|below]]), section '''4.7 Change Gears''', PDF pages 28-29, but see below for mesh adjustment. The LittleMachineShop.com "Mini Lathe User’s Guide" (also below) section '''Threading''' gives a far better explanation, with pictures and diagrams, but its for a lathe with a US 1/16 inch pitch leadscrew, not a metric 1.5 mm pitch one like ours, so you *MUST* ignore all the tables in that section, replacing them with metric mini-lathe (with 1.5 mm pitch leadscrew) equivalents. <br />
<br />
We have the following tooth count gears: 20,20, 30, 35, 40,40, 45, 50,50, 60,60, 80,80<br />
which consist of the OEM power feed gears + the metric change gear set. Apart from the metal 20 tooth pinions, they are all plastic, probably Delrin if the molded in 'POM' marking can be trusted, but possibly plain Nylon 6, and are metric Module 1.<br />
<br />
If we wanted to add the capability to cut US/Imperial threads we'd need to buy additional 55, 57 and 65 tooth gears, and possibly a 21 tooth metal pinion.<br />
<br />
CGTK's [https://www.cgtk.co.uk/metalwork/calculators/changegears/minilathe?gears1=20,20,30,35,40,40,45&gears2=50,50,60,60,80,80&gears3= Change Gear Calculator] ''(link preloaded with our gear list)'' is useful if you don't want to calculate the ratios from first principles. Not all suggested combos will physically fit.<br />
<br />
* Take care *NOT* to loose the keys in the A and D shaft keyways - turn each shaft till the keyway is up before removing the gear. <br />
* The B and C gears are coupled by a hollow stub shaft (with an integral key), which is so tight in the gears it has to be pressed or driven out - I've made a puller just for this task, kept in the change gears tin.<br />
* The center of the B-C stub shaft *MUST* be lubricated where it runs on its pin on the change gear banjo bracket, with grease or heavy oil. ''Seizure of the stub shaft due to running dry is a frequent cause of catastrophic mini-lathe geartrain failures!''<br />
* Don't get oil on the change gears as it can cause plastic gears to crack. Only PTFE drylube or plastic compatible white grease should be used on their teeth. <br />
* Adjust the B-C pin position in the straight slot first to set the C to D gear mesh, tighten its nut, then swing the whole banjo about the D shaft boss to set the A to B mesh, and finally tighten the banjo clamping nut.<br />
* Check both gear meshes have running clearance by turning the chuck by hand enough to complete one full turn of the leadscrew, and by attempting to turn the intermediate gear(s) to assess backlash, If excessive resistance is felt or if there's significant backlash, readjust the gears. If you have difficulty judging the mesh, a strip of 80 gsm copier paper (approx. 0.1 mm thick) wound into the meshing teeth before tightening the stud or banjo will give appropriate clearance once removed. Once setup, check the gears run quietly under power.<br />
* If the sum of the tooth counts C+D is the same as for the ones you just removed and they were correctly meshed, you don't need to move the stub shaft pin. If A+B is <u>also</u> the same, you don't need to move the banjo. e.g. If it was set up for 16:1 reduction power feed, 1 mm (40:60 - 50:50) for M6 and 1.5 mm (e.g. 40:60:40) for M10 pitches can thus be achieved by only swapping gears. <br />
<br />
''The change gears, puller, etc. and a box spanner for the banjo nut are kept in a white rectangular tin behind the lathe.''<br />
<br />
=== Power Feed ===<br />
When used for turning with power feed, the change gears should be set for a 16:1 reduction (A:20 : B:80 - C:20 : D:80) using the pair of small metal 20 tooth pinions and the 80 tooth plastic gears (largest in set), for a feed of 0.09375 mm per turn (1.5 mm/16). Unless continuing your threading project the next session, please re-fit the 16:1 power feed set after threading so the power feed is ready for use. <br />
<br />
* *ALWAYS* leave the feed direction selector lever in its neutral (no feed) position, and the half-nuts open after use.<br />
* *ALWAYS* check the carriage lock is disengaged before engaging power feed. Unlock the carriage after use. <br />
<br />
=== Threading Dial ===<br />
The threading dial is an aid to re-engaging the half-nuts at the right moment so the tool will retrace its previous path cutting deeper, rather than offsetting axially some fraction of the thread pitch and ruining your work. Its based on the concept of the lowest integer multiples of the leadscrew and thread ''(being cut)'' pitches that exactly match, but for mechanical simplicity it only covers certain selected multiples of the leadscrew pitch.<br />
<br />
We have a choice of three pinion gears:<br />
{| class=wikitable<br />
|+ Threading dial Pinion Gears<br />
|-<br />
! Teeth !! Colour Dot !! Usable lines !! OD gear !! Dist. per turn<br />
|-<br />
| 14 || Red || 1,7 || 7.51 mm || 21 mm<br />
|-<br />
| 15 || Orange || 1,5,9 || 8.05 mm || 22.5 mm<br />
|-<br />
| 16 || Green || 1,4,7,10 || 8.37 mm || 24 mm (2 mm/div)<br />
|}<br />
They are now colour coded, with a paint dot on the gear end face ''(the only non-wear surface)''. The 16 tooth one is normally left on the lathe, but disengaged when not threading to minimise wear on the lead screw. The others are kept in the Change Gear tin.<br />
<br />
There's a threading dial 'pickup' calculator here: https://www.cgtk.co.uk/metalwork/calculators/threaddialindicator <br />
<br />
Initially select ''Lathe:'' '''Custom''', and enter the following below:<br />
* ''Units:'' '''Metric'''<br />
* ''Lead Screw Pitch (mm):'' '''1.5'''<br />
* ''Thread Dial Indicator Gear Teeth:'' '''16,15,14''' <br />
* ''Lines on Thread Dial Indicator:'' '''12''' <br />
* ''Line Marking:'' '''Every Line Numbered'''<br />
Note the teeth list is entered in reverse order so the resulting table highlights any required pinion changes.<br />
<br />
N.B. The dial is only friction clamped to the pinion by its center screw. If you have any reason to suspect it may not be properly aligned: <br />
# With the power off and the carriage unlocked, engage the feed direction lever upwards. You'll probably need to turn the chuck by hand to get it to engage.<br />
# If the threading indicator isn't already engaged, loosen the threading dial support block bolt, pivot the block to engage the pinion with the leadscrew and retighten the bolt.<br />
# Engage the half nuts, again turning the chuck by hand till they drop in. <br />
# Turn the chuck a couple of turns, top towards you to take up any backlash, then lock the carriage, taking care not to push it left while locking it.<br />
# Loosen the screw securing the dial to the pinion.<br />
# Align the '1' line of the dial with the index line, by rotating the dial clockwise, then retighten the screw.<br />
# Don't forget to disengage half-nuts and unlock the carriage!<br />
<br />
The above instructions should result in the half-nuts engaging cleanly when exactly on any valid line when threading towards the headstock. If it is required to thread away from the headstock, there will be a slight offset from the line due to backlash between the spindle gear and leadscrew, so engage slightly early.<br />
<br />
Changing the pinion:<br />
# Loosen the threading dial support block bolt and disengage from the leadscrew.<br />
# Undo dial center screw, and remove it and the dial, dropping the old pinion out the bottom.<br />
# Oil the shaft of the new pinion with a drop of light oil and insert it from below, gear end down.<br />
# Refit dial and screw.<br />
# Check the dial and pinion turn freely with minimal resistance.<br />
# Align as above.<br />
<br />
== Tailstock and Steadies ==<br />
These are mostly used to support long work ''(long with respect to its diameter)'' to improve rigidity, increasing accuracy and reducing chatter. The Tailstock quill is also used with a drill chuck for drilling.<br />
=== Tailstock ===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock base]]<br />
The tailstock can be offset to turn shallow tapers between centers. We don't currently have the accessories to turn between centers, namely <s>a MT3 dead center for the spindle, or</s> any drive dogs for the work. Also realigning the tailstock after turning a taper can be a PITA. The photo shows the tailstock adjusting screw locations ''(C - Lateral, and D - Skew)'' and the block on the baseplate they engage with. Adjustments can only take effect when the tailstock locking lever is eased to take the pressure off the baseplate. As we don't have a MT3 center, one has to turn a fresh point on a test workpiece for a rough tailstock alignment reference. Fine alignment, to avoid inadvertent taper turning, can be done by mounting a long precision ground bar between the chuck (or preferably a center in the spindle), and a dead center in the tailstock and sweeping it with a dial indicator on the carriage. Finally a test cut should be taken at either end of a bar between centers, and the diameters checked with a micrometer. Assuming the bed has previously been properly levelled and shimmed to take out twist ''(not the case at RML as we don't have it bolted down)'', any remaining difference in diameter will be double the tailstock offset, smaller at the tailstock being offset towards the front. Fine adjustment cant be achieved by jacking with the screws, its best to ease the adjusting screws, bump the tailstock into alignment then take up the screws again, checking the alignment is maintained when the tailstock is unlocked and relocked. There is no vertical adjustment, though shims can be added between the tailstock and its base.<br />
<br />
==== Tailstock Quill ====<br />
There is a metric/imperial scale on the top of the quill, read against the end of the tailstock, for depth measurement when drilling. The tailstock quill has a 1.25 mm pitch thread and a 50 division dial. Each division is therefore 0.025 mm, and it only takes 4 full turns of the handwheel to move the quill 5 mm. <br />
<br />
To eject MT2 taper tooling and centers from the tailstock, wind the quill all the way in.<br />
<br />
N.B. The quill anti-rotation pin (dog-tip setscrew + locking nut in top of tailstock near to the quill lock) is only M5. It will sheer if a large diameter drill jams in the work. Please back it out clear of its keyway if using large drills, and use alternative methods of preventing chuck rotation. To re-engage it, crank the quill out till you can see the keyway, align it with the screw and screw in the screw till it gently bottoms out, then back it off a quarter turn. Try twisting the quill to check its properly engaged, then tighten the locking nut gently to hold the screw in position clear of the bottom of the keyway.<br />
<br />
=== Steady Rests ===<br />
We have two, both with brass tips that must be kept lubricated during use.<br />
<br />
The fixed steady mounts on the ways, and is most useful when turning longer work that wont fit through the spindle bore. Adjustment is critical, and the surface the tips run on must be smooth and concentric, as any misalignment that forces the work off center will result in the work wobbling in the chuck, marring it, with a high risk of it becoming un-chucked, which can be dangerous at speed.<br />
<br />
The travelling steady mounts to the headstock side of the carriage to locally resist the deflection of thin long work, due to the cutting forces. It only has two tips, to resist climb, and deflection away from the tool, and requires readjustment after every cutting pass.<br />
<br />
== Tooling and Tool Holders ==<br />
'''Key dimensional data:'''<br />
* The quick change holders accept up to 10 mm shank tools. <br />
* The four way toolpost has 50 mm long sides, a seat width of 15 mm and can clamp tools of up to 5/8" (15.875 mm) shank ''(check this)'', but the slot base is only 10.4 mm below the spindle center so cannot be used with >10 mm shank tooling unless it has a dropped tip. Large tooling with a centered tip is also problematic as you run out of height above the shank when trying to shim to match the spindle center height. <br />
<br />
===Quick Change Toolpost===<br />
I've got the quick change toolpost and toolholders setup for mostly easy use. The three toolholders came with cantilever height setting arms which historically haven't been installed as the supplied fixing screws were too short. That's all now sorted out and a HSS RH turning tool and a HSS hand-ground grooving/parting-off tool are now mounted in two of the holders and set to height. The third is kept free for other tools. <br />
<br />
The quick change toolpost has been modified with a spring to press the dovetail clamp outwards and help stop it twisting or flopping about to ease toolholder fitting and removal. The dovetail clamp (socket headed screw on toolpost side opposite dovetail) feels a bit stiffer than before, but will take less than half a turn to go from open (with the toolholder lifting out or dropping in easily) to fully clamped. As there is so much less clearance in the open position you should no longer need to wiggle the toolholder while clamping it to get a consistent height. If the dovetail clamp ever gets misaligned, twist it straight by eye, slacken off a bit further than usual to get a toolholder on, clamp it to align the dovetail then release, reseat the toolholder and re-clamp to ensure its at its preset height. You cant adjust the height by 'jacking' with the height screw due to its offset leverage. Instead, back off the height screw and hold the toolholder at the desired height while locking the dovetail clamp, then adjust the height screw (and locking nut) to hold it there, then check it doesnt change height significantly when you unclamp and reclamp the dovetail. <br />
<br />
Unfortunately the OEM height setting screws foul the toolpost locking nut handle. Currently, if you need to swap toolposts you will have to first remove the quick-change tool holder from the post. There is enough nut handle swing to allow the quick change toolpost to be unclamped and rotated to fine set the tool angle without removing the toolholder. It also seems the mating surfaces may be slightly out of square, as if you rotate the toolpost 90° or 180°, the nut swing may be insufficient to re-clamp it without removing the toolholder to do so. Add a M10 washer under the locking nut if the handle ends up pointing in an undesirable direction! A thin M10 washer is kept with the toolpost collar for this purpose, and will shift the handle position by about a third of a turn. <br />
<br />
''ToDo: Make a taller nut of a similar pattern, to clear the height setting screws.''<br />
<br />
===Four Way Toolpost===<br />
The OEM four way toolpost is significantly more rigid than the quick change toolpost + holders because it has fewer and thicker parts and less overhang. Therefore the four way toolpost should be used when using carbide tooling. It requires shimming under the tool to set the tip height to the spindle center height - see below. The tool shanks are mostly significantly less than 15 mm wide, so need to be centered under its clamping screws, tempting as it is push the shank in for full side contact with the toolpost. If possible clamp the shank with all three screws not just two.<br />
<br />
==== Shimming ====<br />
We typically only mount up to two tools, and want maximum rigidity, so use 50 mm x 15 mm shims, (the full seat area), preferably with deburred edges and radiused corners so they aren't a hazard to the operator.<br />
<br />
We have pre-cut and marked shims of the following thicknesses: <br />
* 1x 3.23 mm, 2.42 mm, 1.56 mm, 0.32 mm, and 0.25 mm<br />
* 2x 1.00 mm, 0.77 mm, 0.12 mm, 0.11 mm, 0.10 mm and 0.05 mm<br />
* 4x 0.53 mm<br />
<br />
Our shims are mostly found materials (hence the awkward thicknesses) and are mostly a mixture of aluminium and steel, with a couple of GRP ones. The toolpost seat '''<u>must be absolutely clean</u>''' to avoid embedding debris in the aluminium or GRP shims, to get a consistent height and avoid tilting the tool - wipe it every time you change a tool! Put the thin shims at the bottom of the stack to avoid the tool shank edges creasing them. Shims are kept in a little yellow plastic box with a clear lid, near the carbide tools case.<br />
<br />
I made a tool height setting gauge (T shaped black acrylic with steps in its sides) which can be used to check the tool tip height matches the spindle center height using either the flat of the ways or the saddle as a reference. The tool tip should just fit under the lip of the appropriate step, with the T arms across the ways flats or on the saddle. It is kept in the box with the carbide insert tools.<br />
<br />
''ToDo:'' <br />
<br />
* ''Cut more shims neatly, mark them with their thickness.''<br />
* <s>''Do test cuts and start noting shim stack-ups for various tools.''</s><br />
* ''Organise shim storage!''<br />
<br />
=== HSS Tools ===<br />
[[File:Tool Bit Geometry.jpeg|thumb|Single point cutting tool geometry]]<br />
Our HSS tools are made from 8 mm square bar stock, hand-ground to tip profile in-house. See LittleMachineShop's [https://littlemachineshop.com/images/gallery/instructions/grindingtoolbits.pdf Grinding Tool Bits] notes. <br />
<br />
I've installed our usual HSS LH turning and parting off tools in two of the quick change holders and set the heights correctly. There are a couple of other HSS tools or tool blanks knocking about. Taking heavy cuts turning steel (even with good cutting oil) blunts HSS tools fairly quickly, which are time-consuming to re-sharpen nicely without a dedicated tool & cutter grinder with appropriate jigs. Its worth noting that the usual 'speeds & feeds' tables are commonly based on surface speeds expected to give a half hour (active cutting) tool life before resharpening.<br />
<br />
I touched up the LH turning tool by lapping on wet & dry (silicon carbide) paper on glass (Aka: [https://en.wikipedia.org/wiki/Scary_sharp 'Scary Sharp']) working upwards through the grits 200, 400, 600 and finally 1000, initially 'bluing' the surfaces to be lapped with a marker pen to see which areas needed taking down more. The end of the tool was significantly uneven so I touched that up freehand on the bench grinder to flatten it when it became apparent that 200 grit lapping wasn't cutting where it needed to. There was an existing micro-bevel on the leading side, which I kept. Finally I 'dubbed' the leading corner vertical edge on the 1000 grit to give it a very slight nose radius. A test cut on brass gave a very nice finish when turning.<br />
<br />
''Ian B has purchased some spare 8mm HSS tool blanks - talk to a lathe trainer if your proposed lathe work needs custom ground HSS tooling.'''<br />
<br />
=== Brazed Tungsten Carbide Tools ===<br />
Somewhat of a half-way house between hand ground HSS tooling and insert tooling with the disadvantages of both and some more besides - e.g. they are much harder to sharpen. So why do we bother? Some tool geometries would be awkward and tedious to hand grind, and Chinese import brazed carbide tooling is about half the price of similar HSS tooling, and far more readily available. Also, for space constrained tooling like boring bars, if you want carbide, for insert tooling, the size of the insert and its clamping seriously limits the minimum hole diameter you can work in. I have purchased a set of 3/8" shank brazed carbide tipped boring bars, but we currently cant sharpen them, due to lack of a diamond grinding wheel. <br />
<br />
=== Tungsten Carbide Insert Tools===<br />
Decoding ISO insert tooling part numbers: https://www.cutwel.co.uk/blog/learn-the-turning-tool-iso-code-system<br />
[[File:Carbide set.jpg|800px|thumb|left|Our set of Tungsten carbide insert lathe tools (before the new inserts were fitted)]]<br />
<br />
{| class=wikitable<br />
|+ Tools, left to right, (+ last across top):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| SSKCR0610H06 || 75° through boring || SCMT06204 || Long || 6 || 6.34 || ''4.33''<br />
|-<br />
| SSSCR0610H06 || 45° deep facing, internal chamfering || SCMT06204 || Long || 6 || 6.13 || ''4.58''<br />
|-<br />
| SWUCR0610H05 || 93° boring, deep facing || WCMT050308 || Long || 6 || 6.22 || ''4.48''<br />
|-<br />
| SWGCR0810E05 || 90° RH turning & facing || WCMT050308 || Short || 8 || 8.25 || '''2.45'''<br />
|-<br />
| SSSCR0610E06 || 45° turning, chamfering || SCMT06204 || Short || 8 || 8.75 || ''1.93''<br />
|-<br />
| SSBCR0610E06 || 75° RH turning, chamfering || SCMT06204 || Short || 8 || 8.72 || ''1.98''<br />
|-<br />
| LW0810R-04 || 60° external threading || JCL15-120 || Short || 8 || 7.44 * || ''3.28''<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || 8.23 || ''2.5 ?''<br />
|-<br />
| LN0813R-04 || 60° internal threading || JCL15-120 || Long || 7.95 || 7.44 * || ''3.28''<br />
|}<br />
<br />
{| class=wikitable<br />
|+ More Tools, (loose in tin):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || ~8.5 (not in use) ||<br />
|-<br />
| [https://www.glanze.co.uk/product/glanze-12-mm-60-degree-metric-internal-threading-tool/ Glanse SIR0012K11] || 60° internal threading bar || 11IRA60 || Long || 12 dia || ??? || ???<br />
|}<br />
''Shim stack heights in bold are tested, in italic are only calculated.'' ''Tip heights marked * are with new JCL15-120I inserts. The single remaining plain JCL15-120 insert has a slightly higher tip height.''<br />
<br />
Carbide tooling typically requires two to three times more speed than HSS and at least a couple of 'thou' depth of cut for best results.<br />
<br />
Chatter can rapidly kill carbide tooling by chipping the cutting edge. To improve rigidity and reduce the risk of chatter, the cross-slide and compound gib screws need to be well adjusted so there is minimal play in the slides, tool stick-out should be minimised, the four way toolpost should be kept over the cross-slide, and the work should be kept close to the chuck (or otherwise supported by tailstock or steady rest) to avoid excessive deflection.<br />
<br />
Thermal shock is almost instant death to carbide, and when dry cutting the insert tip can run very hot, so do not add extra cutting fluid manually during the cut. Pre-apply what you need, evenly, before starting the cut.<br />
<br />
Parting off or facing to center is high risk - if the tool tip is even slightly below center or if tool or work deflection takes it below center, the work will tend to climb over the tool tip as the cut approaches center, breaking the insert. To avoid this, the tool should be shimmed slightly above center, sufficient to allow for work and tool deflection, and unless very close to the chuck, a steady should be used. Its often preferable to part to a couple of mm dia. remaining then stop and saw through the remainder. Parting off hollow parts is much lower risk.<br />
<br />
Further investigation of the Tungsten carbide insert tool height situation is not encouraging - the so-called 'set' in question does not have a consistent tip height ''(see above table)''! In a real set, the insert seats *should* be machined allowing for the insert thickness to bring all the cutting edges to the same height with respect to the shank underside. However if you place them tip to tip on a table its easy to see there is considerable height variation, so they need to be individually shimmed (or at best, one machined shim will only be right for two or three tools). At this time we don't have dedicated shim stacks for each tool.<br />
<br />
A 2.42 mm thick shim brings the SWGCR0810E05 90° RH turning & facing tool almost exactly to center height, and good results were obtained turning 1" steel pipe. However facing 50mm steel bar stock to center found it to be slightly low, leaving a fractionally under 0.05 mm 'pip' so it needs another 0.03 mm to bring it fractionally above center. Fractionally too high is generally preferable to fractionally too low, due to tool deflection, so adding an 0.05 mm shim to the stack should produce optimum results.<br />
<br />
==== Inserts ====<br />
Ian B has purchased the spare inserts we needed in sets of five. He even was able to get the CK3 parting-off inserts which had been difficult to source!<br />
<br />
Inserts used in above tool set:<br />
* 3x SCMT06204 (square, indexable) https://www.rdgtools.co.uk/acatalog/SCMT-06-Carbide-Insert.html<br />
* 2x WCMT050308 (triangular, indexable) https://www.rdgtools.co.uk/acatalog/WCMT-05-T3-08-5XTIP-8813.html<br />
* 2x JCL15-120 (60 deg threading point) https://www.rdgtools.co.uk/acatalog/X5-JCL-15-120L-THREADING-TIPS-60-DEGREE--X5-TIP---23455.html<br />
* CK3 (parting off) https://www.rdgtools.co.uk/acatalog/CK3-CARBIDE-TIPS---PARTING--BOX-OF-5PCS--9437.html<br />
<br />
Inserts used in other tools:<br />
* 1x CK3 (as above) also missing from spare parting off tool<br />
* 1x 11IRA60 in Glanse threading bar + 1x spare<br />
<br />
=== Drills ===<br />
Various sizes of center drills are kept in a plastic bag next to the wooden accessories tray. There's also a small box of 2.5 mm center drills.<br />
<br />
We have a set of 11 TiN coated HSS drill bits from 1.5 to 8 mm, (in a cylindrical plastic index box) for tailstock drilling of brass, aluminium and non-abrasive plastics. To keep them sharp enough for the precision work we expect from the lathe, please don't use them for steel or reinforced plastics, and don't borrow them for non-lathe use. Metric and US [https://littlemachineshop.com/reference/numberdrillsize.php numbered]/[https://littlemachineshop.com/reference/letterdrillsize.php lettered] general use HSS drill bits are kept in two red metal index boxes next to the drill press.<br />
<br />
== Using the Lathe ==<br />
=== General ===<br />
A cutting speed chart for HSS tooling, published by Model Engineer magazine can be found [https://www.model-engineer.co.uk/sites/7/documents/cutting%20speed%20chart.pdf [here<nowiki>]</nowiki>]. The second row is the target feed rate and the rest of the chart, apart from the diameter column is RPM.<br />
<br />
For carbide tooling cutting iron and steels, recommended speeds are generally three times higher than for HSS, but the CJ18A 2500 RPM max. spindle speed (in high gear) means you can only reach the optimum speed range for over 15 mm dia work. For small diameter work, HSS tooling may well be a better choice.<br />
<br />
An online metric speeds calculator is here: https://www.cgtk.co.uk/metalwork/calculators/cuttingspeeds <br />
<br />
How to do the maths to calculate speeds and feeds: https://www.cutwel.co.uk/blog/speeds-feeds-made-easy<br />
<br />
Making dimensioned parts is primarily done by touching off the tool tip on a reference surface (with the lathe stopped, turning the chuck by hand), zeroing the handwheel dial, then manually counting turns and divisions. When backing off the tool its best to do so by exactly one whole turn so you don't forget the previous dial position. Stopping and measuring the work before taking the final cuts is essential if high accuracy is required. ''I've changed out the dial setscrews for flat tip ones with a tiny slug of solder under them so the dials are now friction fit on their shafts. i.e. if you hold the handle firmly taking up the backlash in the direction of cut, you can zero the dial just by grabbing and twisting it.''<br />
<br />
Carriage movement is less easy to measure as the handwheel is uncalibrated and advances an awkward bit over 19.2 mm per turn. Your options here when shoulders or other features must be exactly positioned are, in order of increasing accuracy: <br />
* Use measuring instruments, scribe the work at the desired length then work to the scribed line. Its often convenient to black the work with a permanent marker, then scribe with the tool tip, turning the chuck by hand.<br />
* for short distances, lock the carriage and use the compound, set parallel to the work<br />
* Set up a long travel dial indicator to measure carriage motion. <br />
N.B. with the leadscrew stopped, and the threading dial engaged, with its default 16 tooth gear, it will make one turn for every 24 mm of carriage movement (2 mm/div). This isn't accurate enough for positioning but is sufficient to check you aren't out by a whole mm or more.<br />
<br />
Do not allow any solvents to contact the chuck guard clear plastic as it will make the plastic brittle, or even craze it, and try to avoid melting it with the work light!<br />
<br />
=== Slide Locks ===<br />
* The carriage can be locked to the ways using the M5 hex screw through the top of the saddle to the left of the cross-slide. Double check the leadscrew is disengaged and the half-nuts open before locking it. Lock it when facing.<br />
* The cross slide can be locked by a M4 socket headed cap screw just in front of its middle gib screw. Locking the cross slide is helpful when turning very shallow conical features where the cross slide handle is in the way of the compound.<br />
* The compound slide can be locked by a M4 socket headed cap screw in line with the edge of the toolpost mount on the side with the gib adjustment screws. In normal use it should be kept backed off half a turn but it is desirable to tighten it for parting off operations to keep the resulting end faces flat.<br />
<br />
=== Chucks and Chuck Jaws ===<br />
==== Terminology ====<br />
* Inside jaws have steps on the outside to grip the ID of hollow work, but can also be used as outside jaws on small diameter parts (i.e. that fit through the spindle). <br />
* Outside jaws have steps on the inside to grip the OD of the work.<br />
* Universal chucks have a scroll plate with a spiral screw thread that moves all the jaws.<br />
* Independent chucks have individual adjusting screws for each jaw.<br />
<br />
==== The Chucks ====<br />
* The three jaw universal chuck can only grip near round or hexagonal work, which it centers, but its concentricity is not perfect so e.g. if you reverse the work and continue turning at the same diameter from the other end, you will see a line where the turned surfaces meet. It has separate sets of inside and outside jaws, and we normally keep the inside set installed to use as outside jaws for small diameter work.<br />
<br />
** Our jaws are individually numbered, stamped in the groove. They must be fitted in the correct sequence. The jaw slots are not clearly marked. Lowest runout for small dia. parts is achieved if you fit the jaws with #1 anticlockwise of the makers mark, then continue anticlockwise for #2 and #3.<br />
** A large strong rubber band is a great help getting all the jaws started on the scroll together - with slots #1 and #3 above the centerline and the scroll thread outer tip between #1 and #3, insert jaws #1 and #2 and put the rubber band round them to keep them in their slots. Insert jaw #3 and stretch the rubber band over it to hold it up into its slot. If the scroll was positioned correctly, all jaws should be at the same initial radius. The jaws can now be cranked in with the chuck key and they should all engage in step so they meet in the middle.<br />
:: ''Mini-lathe.com have the best instructions for [https://www.mini-lathe.com/mini_lathe/chucks/chucks.htm#Installing_Chuck_Jaws changing the jaws].'' <br />
<br />
* The four independent jaw chuck can grip most roundish or squarish work, which can either be carefully centered by the user, or deliberately gripped off-center. <br />
** Its jaws are reversible so can be swapped from inside to outside by simply cranking each jaw out and reinserting it the other way round, one at a time. DON'T move the jaws to different slots as they are likely to bind.<br />
** When setting up to face the sides of rectangular objects held crossways, it may be helpful to use both inside and outside jaw orientations, in symmetrical opposing pairs.<br />
** Its screws move their jaw 1/8" (3.125 mm) per turn<br />
<br />
* The jaws must '''never''' protrude from the chuck OD by more than one step, and for safety, its preferable they don't protrude at all, as they make the gap between the front of the bed and the chuck body an even more unforgiving meat grinder, and as the number of teeth engaged with the scroll or screw decreases, they loose strength, just when you need it the most to grip larger/heavier work. <br />
<br />
''Neither chuck is well suited to gripping tapered work safely. When seating work that doesn't quite fit through the chuck bore (which is larger than the 20mm spindle bore limit), be careful that it isn't seating on the chamfered edge of the chuck bore as it is far to easy to get the work slightly cocked so it doesn't run true.''<br />
<br />
==== Changing Chucks ====<br />
* When changing chucks, use the small grey plastic mat to protect the ways under the jaws in case you drop the chuck.<br />
* The spindle nose has two patterns of holes - the three hole pattern is for the three jaw chuck and the faceplate, and the four hole pattern is for the four jaw chuck. One hole is shared between the patterns, and is marked on the spindle nose.<br />
* To fit a chuck:<br />
** First check that the spindle nose and chuck back and recess are free of swarf, grit or other debris. Any foreign objects will tilt the chuck causing excessive runout and may mar the surfaces.<br />
** Remove the nuts and split lock washers from its studs, line its studs up with the hole pattern (preferably with the stud nearest anticlockwise to the makers mark through the marked spindle hole), fit and hold it in place with your right hand, and with your left, get the lock washer and nut on the top stud, and take up the slack.<br />
** One one nut is on, you no longer have to worry about dropping it, and can work round fitting the remaining washers and nuts, taking up the slack on each as you fit it. <br />
** Next, work round again getting them all finger tight, then tighten them gently, and finally work round fully tightening them. <br />
* Removal is the reverse of refitting. Put the washers and nuts back on the chuck's studs so they don't get lost.<br />
<br />
=== Faceplate Work ===<br />
Faceplate work is probably the most dangerous operation you can (or rather should) perform on a lathe. The working area is a large diameter spinning surface with protruding clamps to fixture the part that it is impractical to guard. Protruding clamps, studs, nuts etc. are very difficult to see at speed.<br />
<br />
'''Treat the faceplate with great respect and caution if you wish to continue to be able to count to ten on your fingers!''' <br />
<br />
The 65 mm cross-slide travel vs the 80 mm faceplate radius is a serious limitation that may require creative compound, toolpost and tool setups for larger parts, and doing full face cuts in two sections.<br />
<br />
''It is common practice to skim the faceplate to ensure it runs true. We have not (yet) done this, and wont till the spindle is in better bearings and the nose reground to minimise runout.''<br />
<br />
==== Clamping ====<br />
Open ended/sided clamps should be oriented so that cutting forces drive the work towards the clamping bolt/stud, not out from under the clamp. Minimize the protruding length of thread past the clamping nut, if necessary using sacrificial bolts or studs you can cut to length, or even using a long M8 stud for one of the faceplate mountings, so you can get a clamp nearer to the faceplate center. Double-check all clamps are secure, manually turn the faceplate to check the work and clamps clear the ways, top-slide and toolpost, and stand out of the 'line of fire' (a disc extending from the faceplate) when spinning up the work for the first time. <br />
<br />
If you need to machine close to a clamp, consider marking a safe limit circle on the faceplate and work with a marker pen to make it easier to see how close the cutting tool is to crash disaster. <br />
<br />
I strongly advise reading chapter two of Tubal Cain's book "Workholding in the Lathe" several times before your first faceplate setup, and if possible get another experienced lathe user to check your first few setups before spinning them up.<br />
<br />
==== Chuck Guard Removal ====<br />
The faceplate is too large diameter to fit under the chuck guard, but the guard has an interlock switch wqhich must be closed for the lathe to run. The guard is now fitted with wing nuts so it can be removed allowing the the interlock switch to close when using the faceplate. It *SHOULD* *ALWAYS* be refitted if a chuck is fitted, except when turning work too large to clear the guard. <br />
<br />
''The chuck guard is primarily there to make it very difficult to start the lathe without removing the chuck key and to reduce the area of large diameter spinning surface exposed. It may slow down the projectile if a chuck sheds a jaw but is unlikely to stop it. Also it serves to contain coolant spray spun off the chuck. As we don't use flood coolant this usually isn't an issue for us. As setting up for faceplate work doesn't use a chuck key, and the most hazardous zone is the face of the faceplate, with its spinning projecting clamps, with full access required for machining operations, which a guard would not cover, the consensus is that removing the guard is an acceptable risk.''<br />
<br />
=== Turning and Facing ===<br />
We are getting good results in aluminium, brass, and even steel using HSS cutting tools in quick-change tool holders, and the ~ 94 um/turn power feed. Unfortunately due to lack of rigidity in both the machine and smaller diameter parts, if you don't want the outer end to be over diameter, a light final cut and multiple 'spring' passes will probably be required.<br />
<br />
For aluminium, a sharp HSS tool and 0.5 mm (20 div) depth of cut gives good results with power feed for rapid stock removal. Its also easy maths as each cut takes ~ 1 mm off the diameter. Finish cuts should be much finer, 0.1 mm (4 div) is 'in the ballpark'.<br />
<br />
For steel, using carbide insert tooling, a 0.25 mm (10 div) depth of cut is more appropriate, and with pre-applied cutting oil, gives reasonable results with power feed if you use enough speed. The maths is not quite so easy as you are only taking 0.5 mm off the diameter per pass. Again, use finer finish cuts but try to plan your cuts so the final cut is still cutting, not smearing the surface!<br />
<br />
When facing or parting off, some skill is required to turn the cross-slide handwheel steadily to get a decent finish and to avoid shock-loading the tool tip. Increasing the spindle speed in one or more steps to keep up with the reducing diameter is advisable, but avoid speeds that cause resonances (resulting in chatter). When parting off, small through-hole parts may be caught on a thin rod chucked in the tailstock, and pre-positioned inside the work with its tip right up to the parting off position.<br />
<br />
==== Using the Steady Rests ====<br />
For the fixed steady rest, see Blondihacks' Lathe Skills #26 - How To Use a Steady Rest! [[#Youtube_Playlists_&_Videos|{below}]]<br />
<br />
Ours doesn't have ball bearing fingers, so a smooth surface on the work and adequate lubrication are essential. The thumbscrews can only tighten the fingers, so for small adjustments outwards you need to either slack off the clamping nuts or ease them slightly and use a drift against the back of the finger's slot. Once set, check the chuck still turns freely.<br />
<br />
The traveling steady rest needs to run on a machined surface, so at least for the first pass, must follow the tool, so its difficult to avoid using more compound slide overhang than is desirable. An initial surface should be cut next to the chuck or tailstock center before fitting the steady rest.<br />
<br />
Both are a PITA to fit - the fixed one has to have its clamping post inserted up through the bed, and the supplied spanner is useless near the headstock, and the travelling one's mounting holes on the saddle almost invariably need swarf picked out of them.<br />
<br />
==== Turning Between Centers ====<br />
<s>Using a MT3 to MT2 reducing sleeve, the MT2 dead center can be fitted in the spindle.</s> ''Currently the MT3 spindle taper is compromised.'' Alternatively, a soft center can be turned immediately before use in the three jaw chuck, but that must have its 60° point re-cut to concentric if the chuck is disturbed, and needs to be either large enough to bear on the chuck body, or must have a lip to bear on the end face of the jaws to take the axial thrust. Recutting the center is a PITA, as the compound angle must be set to 30° anticlockwise, then reset to a true 0° afterwards. Maybe a right-hand 30° end angle zero rake form tool is the answer, or use the carbide insert tool SSKCR0610H06 as a form tool with the toolpost rotated 15° anticlockwise.<br />
<br />
With the MT2 live center in the tailstock quill, this gives us a center either end of the work to hold it.<br />
<br />
We also need a drive dog similar to [https://littlemachineshop.com/products/product_view.php?ProductID=4473&category=1 this], and the corresponding drive post to bolt to the spindle nose. I have some 25mm bore thick wall iron pipe, which should do nicely. Lengths of the dog's straight tail and of the post TBD after I check how much the center protrudes. N.B. its recommended to tie the tail to the post to keep them in contact so they don't slam. ''Currently we will need to drive from the chuck jaws. Possibly use the exterior jaws with a short soft center gripped on the inside end and drive from the highest step.''<br />
<br />
=== Drilling ===<br />
Always start with a center drill so deflection of longer bits doesn't start the hole off-center. For larger bits (> 5 mm), first drill to the web size, then to final diameter. For a precision hole, drill slightly undersize and ream to final diameter. ''Supply your own reamers!''<br />
<br />
Caution: See note about the quill anti-rotation pin in section [[#Tailstock Quill|Tailstock Quill]] above.<br />
<br />
=== Boring ===<br />
Caution: As the spindle doesn't extend right through the headstock housing, if boring in a through hole, chips tend to fall out the back and tumble in the spindle bore till they fall into the change gears. To avoid this, one should plug the spindle bore with a wad of paper towel or rag and when cleaning up afterwards, use a rod to push it through towards the tailstock, with the chuck jaws (if fitted) wound clear of the spindle bore.<br />
<br />
A swivel bladed hole deburring tool (pale blue handle) can be found in the main room on the windowsill behind the drill press.<br />
<br />
A couple of boring jobs have been bodged with an awkwardly angled turning tool and achieving acceptable effective rake with enough clearance to reach deep enough into the hole has been problematic. I reviewed the tools we had and found none suitable for starting out in a 13mm bore, the max diameter we can (easily) drill. I therefore decided to buy a set of boring bars and make a holder for them. I had difficulty finding anything affordable under 10mm shank - the best low cost option was a [https://www.amazon.co.uk/dp/B07P5LGVBX set of nine 3/8" (9.525 mm) shank brazed carbide tipped boring bars], which would be close to the max capacity of the quick change boring bar holder - if we had one! Unfortunately this holder for our specific toolpost is difficult to find except in a toolpost bundle. Another annoyance is the variable tip height of the set, varying from 1.8 mm to 2.8 mm above the center of the shank.<br />
<br />
I therefore decided to make a boring bar holder of the [https://littlemachineshop.com/products/product_view.php?ProductID=1700 Littlemachineshop.com (USA) style] for use in the four way toolpost, as the additional rigidity will certainly help. Starting with a slightly over 50 mm length of 16 mm aluminium square bar and using the four jaw chuck , both ends were faced and an attempt was made to find its center and center drill it. It was then drilled out to ~9.8 mm after much drama due to blunt drills and drills that cut ~1mm oversize. Too big, but beggars cant be choosers as we didn't have a boring bar holder or a 3/8" reamer. Unfortunately the final hole ended up significantly off center. It was then chucked crossways and ~1 mm skimmed off its thickest side to gain clearance to allow it to be shimmed to height, then one side was slit lengthwise manually with a hacksaw.<br />
<br />
It was fitted to the for way toolpost and loaded with a booring bar, which clamped firmly. A 0.86 mm shim stack brought the tip of the largest boring bar almost spot on center height, with the difference easily accommodated by twisting the tool slightly. The three jaw chuck was then remounted, and a piece of iron pipe chucked for a test. It cuts well and leaves a decent surface finish.<br />
<br />
''The boring bar setup is a work in progress - talk to me before attempting to use them if you have a project that would benefit from boring..''<br />
<br />
ToDo: get something that can sharpen tools tipped with this grade of carbide - it needs some sort of diamond (or possibly CBN) wheel as green grit silicon carbide does little more than polish it. ''N.B. diamond wheels are rapidly eroded by grinding steel, so the supporting steel seat must be undercut with a regular grinding wheel before the diamond wheel can contact it.'' <br />
<br />
We'll also need 50 mm square sheet shims to fit under the toolpost to gain clearance in the toolpost above the tool or toolholder. A 2.4 mm shim would give us about the same above and below spindle center height, and we probably need a small selection of thinner ones.<br />
<br />
=== Thread Cutting ===<br />
The objective is to cut a thread that complies with the ISO metric thread profile. Our lathe is not currently equipped to cut non-metric threads, (with the exception of BA which have pitches based on metric threads of that era).<br />
<br />
[[File:ISO and UTS Thread Dimensions.svg|frame|center|Metric Thread Profile - from the geometry, H is ~86.6% of P]]<br />
<br />
Metric thread data - See 'Preferred Sizes' at: https://en.wikipedia.org/wiki/ISO_metric_screw_thread<br />
<br />
See "Mini Lathe User’s Guide" section '''Threading''' for general techniques *ONLY*, and above for change gears and threading dial setup.<br />
<br />
Amadeal specify the max. thread pitch as 2.5 mm. Any thread pitch greater than 1.5 nn requires the change gears to gear up. When gearing up it is desirable to distribute the ratio as evenly as possible over the two pairs of gears in the geartrain to avoid excessive tooth loading.<br />
<br />
==== External Threading ====<br />
Initially turn work to required Major Diameter, set up change gears and threading tool, touch off on the work, zero the top and cross slide dials, and do a 'scratch' pass to check the pitch. Back off the tool, return the carriage, and re-engage the half nuts on a valid dial line clear of the end of the thread then immediately stop the lathe, and hand turn the chuck till the tool tip is (hopefully) over the scratch to check the thread pickup. If all is good, return the carriage again, restart the lathe and start cutting your thread. <br />
<br />
Methods of doing so vary depending on the size of the thread and toughness of the metal, but straight-in plunge cutting is generally to be avoided as has the highest cutting forces, and does not reliably keep the carriage (and top-slide if set parallel to the work) loaded to avoid pitch errors due to backlash. <br />
<br />
If leaving the half-nuts engaged and reversing the lathe to return to the start of the thread for the next pass, its absolutely essential to back the tool out of the thread for the return pass as it will not follow the path of the cutting pass due to backlash in the geartrain, leadscrew mounts and half-nuts.<br />
<br />
==== Internal Threading ====<br />
''<nothing here yet>''<br />
<br />
== Cutting fluids ==<br />
=== Why bother? ===<br />
[https://youtu.be/mRuSYQ5Npek Watch this video] and contemplate what's actually happening to that thin ribbon of metal being removed. Most of the lathe's motor power is being turned into heat by internal friction in the chip being removed in the zone around the cutting edge, and surface friction at, and immediately behind the cutting edge, near-instantly heating the chip by up to several hundred degrees. Reducing the surface friction using a suitable cutting oil reduces the strain on the machine as a whole, and reduces workpiece and tool heating (and thus expansion) with consequent improvements in maximum usable feed and depth of cut, surface finish and accuracy. It also drastically increases the life of the cutting edge.<br />
<br />
=== Practicalities === <br />
We don't have a coolant system for the lathe and *really* don't want the maintenance hassles of using soluble cutting oil/coolant as if used infrequently its a PITA to keep recirculated high water content cutting fluids from going rancid and stinky, and they can also rust the ways, so even a total loss gravity feed system is problematic. Therefore if dry machining doesn't give a good enough finish, we tend to use oil applied topically, by hand to the work. <br />
<br />
* Hard brass is typically free-turning without oil, however some light oil for the final cut can improve surface finish, but with the disadvantage that it will increase loose chip buildup on the tool as hard brass typically forms short spalls or splinters rather than curly chips.<br />
<br />
* Many Aluminium alloys tend to be gummy, and Paraffin or other mineral spirits mixed with a little oil can help prevent the aluminum welding to the tool edge. WD40 will do at a pinch, but its messy to apply from a spray can.<br />
<br />
* Steel really needs *GOOD* cutting oil. Lard oil is the traditional choice for steel. If there are any objections to lard oil, we should bite the bullet and get some commercial dark high Sulphur cutting oil, but beware, many such oils use an additive package that includes lard oil.<br />
* Cast iron (except ductile) should be cut dry, as the carbon micro-inclusions self-lubricate it, and the carbide in the dust (primarily Cementite) are very abrasive, so tend to form a grinding compound if mixed with oil. <br />
<br />
I've sorted out an oil pot lid with a 1/2" brass collar soldered in to give a nice smooth sided hole, for ease of use and to minimize the risk of spills when using a brush to apply cutting oils, and got some dirt-cheap brushes. It fits Shippam's paste (and similar own-brand spread) jars and I've found several jars and ordinary lids to seal them for storage. Unfortunately it isn't the easiest to get this type of jars' lids back on square so they seal properly, and if you over-tighten them and there's a temperature change, they can be a total <expletive> to reopen. Using the rubberised handles of a large pair of pliers to grip the jar lid just above its rim is the best option, and avoids damaging the lids.<br />
<br />
''N.B. For the smaller brushes, the glue holding the bristles in is attacked by paraffin. To prevent loss of bristles, crimp the aluminium ferrule of each new brush of this type before use.''<br />
<br />
We have, in labelled jars:<br />
<br />
* Sulphurised Lard oil thinned with paraffin. Best choice for heavy cuts and threading in steel but stinky.<br />
* Lard oil thinned with paraffin. Good for steel and acceptable for softer copper alloys<br />
* Paraffin with a trace of light oil. Good for aluminium, and can help prevent squealing chatter on finish cuts in brass.<br />
<br />
I've also got some paraffin wax (in the form of a stubby candle), which can be applied lightly (under power) to brass and aluminium stock especially on the finish pass. It makes less mess than oil but unfortunately tends to build up on the tool tip, making it difficult to 'work by eye' without frequent pauses to clean the tool tip.<br />
<br />
We've also got a tin of [https://www.rocol.com/products/rtd-compound Rocol RTD cutting compound], which is a thick paste. Its highly recommended for drilling and tapping steel (in the drill press or by hand), but as a paste, is less useful for general lathe work unless thinned to a fluid consistency, e.g. with paraffin or white spirits. OTOH its certainly worth trying for high speed facing steel as it is less likely to get flung off.<br />
<br />
== Cleaning and Maintenance ==<br />
Swarf is a significant cut hazard to the operator, especially stringy swarf from cutting steel. Never touch it bare-handed - always use a tool e.g. a brush, or a hook, or needle nose pliers for grabbing long swarf.<br />
<br />
* After use, brush all swarf off the toolholder, compound and cross slide etc. ways and leadscrew. Ian B has blocked off the opening at the headstock end of the rear splashguard (to try to keep swarf out of the motor), so one must sweep the swarf towards the open tailstock end and catch it in a dustpan or similar. Preferably, also thoroughly clean out the chip tray under the lathe, but at least sweep out visible swarf.<br />
* Wipe up any cutting fluid residue and re-lubricate affected sliding surfaces with way oil.<br />
* Do not solvent clean the chuck guard, as it will make the plastic brittle, or even craze it. Water with a little detergent is permissible for cleaning it, with the guard totally removed from the lathe.<br />
<br />
Before engaging the half-nuts for power feed/threading, check the leadscrew is clean! ''Best cleaned under power, with a toothbrush.'' <br />
<br />
'''Caution:''' The traverse gears behind the carriage handwheel are in an open-backed housing and tend to become packed with swarf! Swarf buildup here will result in jerky carriage movement. Clean out as much as you can with a toothbrush ...<br />
<br />
===Lack of lubrication and/or swarf or dirt build-up can be disastrous===<br />
* If using the change gears/power feed, lack of lubrication of the B-C stub shaft center pin or either leadscrew end bearing can result in seizure and immediate destruction of one or more gears in the gear train or worse. <br />
* Small pieces of swarf can get between the saddle and ways, or into the slides degrading accuracy, possibly permanently if hard swarf scores them, or jamming them. The carriage handwheel gears behind the apron are notorious for accumulating swarf, and swarf buildup on the leadscrew can prevent the half-nuts engaging properly, resulting in scrapped work, and possibly stripped half-nuts. <br />
* Metal swarf can get into the motor (''though Ian B has modified the rear chip catcher to reduce the risk)'' or into the control box via the leadscrew, and short-circuit stuff. At best it will blow the fuse and need a strip-down to clean it out, at worst it may require a replacement [https://www.amadeal.co.uk/acatalog/Speed-Control-Circuit-Board--12amp-AMA_SP_CJ18_SCB12.html#SID=12 speed controller] ''(currently £96)'' and/or [https://www.amadeal.co.uk/acatalog/550W-motor-for-CJ18A-Mini-Lathe-467.html#SID=240 motor] ''(currently £105)'' and possibly other electrical parts. We should probably fit a [https://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C3-Mini-Lathe-Spares/C3-256-Leadscrew-Grommet-Dustproof-Cover C3-256 Leadscrew Grommet] to keep swarf out of the control box, as it tends to drop onto the 'Filter' board which is mounted horizontally, below the leadscrew.<br />
* Grit from grinding, sanding etc. forms a grinding paste with the way oil, and will rapidly wear out the ways, saddle and slides. Keep grit off at all costs e.g. by covering the ways and slides during grinding/sanding operations, and if there's any chance grit has gotten where it shouldn't, clean and re-lubricate *BEFORE* moving the carriage or slides, then move the carriage and slides, wipe down where they were with a clean paper towel and check there's no remaining traces of dirt other than clean way oil on the paper towel. If it doesn't come clean when you re-lubricate and move it again, a full strip down may be required to solvent clean and relubricate the precision sliding surfaces.<br />
* Although a metalworking lathe *can* be used to turn hardwood, wood dust and small chips are extremely pernicious, as they get everywhere, even clinging to clean surfaces, are abrasive due to their silica content, and are hygroscopic, promoting rust. An even more thorough clean-up than after using abrasives is needed, immediately afterwards. Oily wood dust and fine wood chips in significant quantities are a fire hazard, even in the trash bin.<br />
<br />
===Lubrication===<br />
See section: "Lubrication" in LittleMachineShop.com "Mini Lathe User’s Guide" [[Ian_M's_Lathe_Notes#Manuals|(below)]]. As we usually only open two nights a week, in the table on page 16, Daily lubrication becomes Weekly and Weekly becomes Monthly.<br />
<br />
===General Maintenance===<br />
* The grubscrews holding the cross-slide and compound slide dials tend to loosen due to vibration and use of the dials. Keep them snugged up, but not so tight the dials cant be set without an Allen key.<br />
<br />
* The screws holding the cross-slide nut tend to work loose due to vibration. Crank the handle to and fro through the backlash and visually check there is no movement of the screw heads in their holes. If there is, see the [[#Excessive_cross-slide_backlash|notes below]].<br />
<br />
===Removing the Carriage===<br />
Its possible to remove the carriage from the bed for cleaning etc. without dismantling it. The only stop to its motion is the righthand leadscrew bearing.<br />
<br />
Start by removing the tailstock. Crank the carriage to the tailstock end then remove the leadscrew bearing (two screws and a nyloc nut on the leadscrew end). With the half-nuts open, hold the leadscrew centered in them and crank the carriage off the end of its rack, then slide it off the end of the bed.<br />
<br />
Refitting is the reverse of removal, except (if its gibs are correctly adjusted) the carriage will be very tight on the end of the bed ways so may be difficult to work onto the ways without a stack of blocks of wood or similar to support it at exactly the right height. The righthand leadscrew bearing must be refitted with the carriage as close as possible to it and the half-nuts firmly closed to support the leadscrew at the correct height to hold it in alignment while the screws are being tightened. The nyloc nut controls leadscrew end-play. Fully tighten it then back it off slightly till the leadscrew turns freely with its change gear removed.<br />
<br />
If the Apron has been off, refit it with the screws no more than lightly finger tight and only finally tighten them after checking lead screw engagement at both ends of the carriage travel and that the rack and pinion operates smoothly over the full travel.<br />
<br />
== Issues and Annoyances ==<br />
As of September 2023 - mostly resolved, apart from the spindle bearings and runout, the lathe is in better condition than it has been for a number of years.<br />
<br />
===Four Jaw Chuck has two jaws too tight===<br />
Fixed 27/10/2023: The grooves in the opposite sides of the jaws that run in the chuck slots were slightly out of true, and the rails either side of the slots were slightly too thick towards the center. Due to the difficulty of seeing the high spots, after cleaning up and deburring the jaws didn't do enough to ease them, I decided to grind the top of the rails where they were binding. Several repetitions of spotting, grinding then diamond filing the high spots has eased them enough. I cleaned everything, greased the jaw slides and screws, and refitted the studs so the chuck is now fit for service. <s>Two of the chuck jaws are tight in their slots, making precise adjustment difficult due to lack of 'feel'. Moving the jaws round the slots shows the problem follows the jaw not the slot, and stoning various edges hasn't helped so it seems that the affected jaws are slightly oversize. Need Engineer's spotting blue to determine which of the sliding surfaces is binding, so we can see what needs scraping/stoning/grinding to fix them</s><br />
<br />
''N.B. Don't move the jaws to a different slot - the formerly tight jaws *must* stay in the slots furthest from the makers mark.''<br />
<br />
===Excessive Runout===<br />
Mostly fixed 24/10/2022: I ground the chuck seating surface of the spindle nose (outside lip) to under half a thou runout. This also cleaned up several burrs. It would be possible to do better, but that would need good spindle bearings, and a more rigid toolpost grinder mount.<br />
<br />
Our spindle nose was damaged years ago by a person with little mechanical aptitude (who shall remain nameless) beating it up with a hammer mushrooming the spindle nose. We are getting several thousandths runout at the end of the MT3 bore, a MT3 to MT2 reducer sleeve in it runs visibly out of true, as does the spindle nose flange. When you put a chuck on it, the runout is magnified by the distance from the spindle nose. Ideally we would replace the spindle when we change the bearings but its £52 [https://www.amadeal.co.uk/acatalog/4-Spindle-Upgrade-Real-Bull-Mini-lathe-CJ18-series-AMA_SP_CJ18_003RB.html#SID=9 from Amadeal] and money is tight. It may well require more work after the bearing upgrade. Once good bearings are in, if we can borrow a decent MT3 arbour as a reference, we should consider skimming the bore.<br />
<br />
===Spindle bearings===<br />
* The spindle bearings appear to be close to worn out. They are notably noisy when running, and there appears to be more slop in the spindle than is desirable. We have some ideas for possible replacement/upgrade, but it requires a major teardown.<br />
<br />
: The original bearings are allegedly 6206-2RS or 6206-ZZ deep groove ball bearings - 2RS codes rubber seals both sides and ZZ codes metal shields. Although the deep groove gives reasonable ability to withstand axial loads, the bearing balls point contact means they are vulnerable to [https://en.wikipedia.org/wiki/Brinelling brinelling] due to shock loading. The jammed on three jaw chuck didn't help this, as before we skimmed the spindle nose lip, it had to be driven off using a bar through the spindle bore, shock loading the bearings every time. Also even a minor 'crash' could have brinelled them due to eccentric shock loading, and the lathe has previously been crashed badly enough to need drive gear replacement. There are also issues with the 'approved' method of spindle and bearing removal from the headstock brinelling them, even if you don't abuse the spindle nose with a hammer!<br />
<br />
: A possible replacement is 30206 tapered roller bearings. The new bearings are slightly thicker so the plastic spindle spacer (15) needs to be machined to length to get the 45 tooth spur gear that drives the change gears laterally aligned with the tumbler gears. If a temporary replacement (3D printed?) is fitted, the lathe can be run (without power feed capability) so this can be done on the lathe after fitting the new bearings. As tapered roller bearings have line contact, they are significantly more resistant to brinelling.<br />
<br />
: ''See [[Talk:Ian_M%27s_Lathe_Notes]] for notes, links etc. for this upgrade.''<br />
<br />
===Motor stuttering===<br />
* Fixed 21/09/2023: The motor was running very erratically and it was very difficult to set a speed. Several loose connections were found in the control box, mostly loose female spades to the motor controller board, but also a dry jointed braking resistor on the 'Filter' board, and an inhibit wire completely off its terminal on the forward/reverse switch, making intermittent contact. After tightening and/or remaking all affected connections, it was much improved but still not right below 300 RPM. The remaining issues were due to poor wiper contact in the speed control pot, and stripping it, cleaning the track and contact ring and re-tensioning the contacts resulted in the motor now running smoothly over the full speed range. The speed is slow to settle, and while part of that is probably the lag in the digital tach, I suspect that the KBIC motor speed controller isn't properly tuned as it was (allegedly) previously replaced.<br />
<br />
===Drive belt slipping===<br />
* Fixed 28/9/2022: During testing the motor after the above issue, it was noted that the chuck could be stalled, slipping the drive belt, with not much torque. The drive belt was determined to be loose and a bit worn, but still in acceptable condition. <br />
<br />
: Access for servicing the belt requires removing the control box ''(2 spades to ZVR switch disconnect the supply, speed sensor and motor simply unplug from the 'filter board')'', the motor cover, chuck guard switch assembly + wiring cover, the change gear 'A' (drive) shaft carrier assembly, and the tumbler gear assembly. See https://youtu.be/EkxlIz01BdA for disassembly/reassembly, though on our lathe, the speed encoder ring on the spindle prevents the belt cover from being fully removed without disturbing the spindle nuts. There is enough room to work with it loose, but still trapped by the encoder ring. Also, unlike the video, if the 'jack' screws under the headstock are correctly adjusted, and the studs aren't excessively bent, there is no need to make custom studs. <br />
<br />
: It turns out that our lathe was missing the M6 hex headed jack screws that press the motor down to resist the belt tension, and the motor had cocked out of position at a severe angle. I know Ian B had had considerable trouble adjusting it after the motor fault back in October 2022, and I believe it had been getting slowly worse ever since. The jack screws were probably mistaken for headstock fixing bolts during disassembly after the crash that resulted in the metal Hi/Lo gears being fitted, then lost. The penny washers on the studs had dished, so I turned them over and backed them up with smaller washers and switched to nyloc nuts so they cant back off due to vibration. N.B. there is a packing washer on the motor side on one of the studs, presumably so the shaft is true to the ways. Adjusting the motor is awkward to say the least. One has to slack the stud nuts off a lot, pry under its rear end to lift it enough to be parallel to the ways, snug the stud nuts, check alignment, then set the jack screws and their lock nuts to hold it there, and finally tighten the stud nuts. <br />
<br />
: Tension: According to Sieg, it should be possible to twist the belt 90° mid span with a light finger grip. Other sources say 1/32" - 3/32" deflection mid span with light finger pressure.<br />
<br />
===Speed display blanking===<br />
* The speed display has been intermittent, blanking and flashing 8888 and 0 at certain speeds for as long as I have been using the lathe. Finally on 18/07/2022 it failed completely, with no display. I removed the display module and bench tested it - the pins are labelled 5V GND PL PE, PE is frame ground and PL is a TTL level pulse from the speed sensor - confirming that it was in good working order. My suspicions then turned to its power supply on the 'Filter' board. With both the sensor and display unplugged, the 5V rail was found to have a only a couple of volts, but the unreg DC was 17V and stable. Replacing the 78L05 5V regulator restored the 5V rail and normal operation.<br />
<br />
: ''I conclude its been failing for a while with high load current due to speeds with more lit segments causing it to drop out, resetting the speed display, causing it to blank, lowering the current enough for the regulator to recover, then the display MCU lamp tests (8888) then re-acquires the speed, repeating ad-nauseum till the speed is changed. I don't like the design as the high input voltage results in excessive dissipation.'' <br />
<br />
: ''ToDo: Bench test display to measure its worst case current consumption, then fit an appropriate dropper resistor to reduce the 78L05 dissipation.''<br />
<br />
===Quill spinning when drilling===<br />
* The quill was tending to spin while drilling because its anti-rotation pin (a M5 dog tip setscrew) was sheered. I've removed the debris, aligned the scale with the top of the tailstock and fitted a longer M5 dog-tip setscrew to replace it, with a nut to lock it at the correct height. N.B. the pin isn't that 'meaty' so if using big drills in tough metals, to prevent shearing it, it should be backed out so the quill can be turned by hand and unwanted rotation controlled by being quick with the quill lock if it starts to spin, or even using a close fitting rod in one of the chuck key holes with plastic tube over it to protect the ways. <br />
: ''If the screw sheers again, the quill will need to be removed and the tailstock taken off the lathe so the sheered tip can be shaken out, and if the setscrew is difficult to remove it probably means the threads are mangled where it sheered. Try driving it right through with the quill out.''<br />
<br />
===Sloppy quick change toolpost locking mechanism===<br />
* Once the dovetail clamp screw was slackened, there was nothing preventing the dovetail twisting or cocking significantly, and friction with the toolholder made it tend to do so, making toolholder insertion and removal more difficult unless the clamping screw was backed off excessively. I added a compression spring around the clamp screw inside the toolpost to push the dovetail outwards so it mostly retains alignment when open, allowing toolholders to slide on or off cleanly with far less screw slackening.<br />
<br />
===Leadscrew rubbing===<br />
* The leadscrew shaft is rubbing on the insulating separator inside the control box. Unfortunately the corner of the relay on the Filter Control Board (#160) doesn't allow enough clearance. Although the friction isn't much of a problem at high reduction ratios, e.g. 16:1 power feed, it increases the stress on the change gear train, and may be problematic when threading at feeds above 1:1. ''Possibly pack out the control box mountings by a couple of mm.'' <br />
<br />
===High/Low lever backwards!===<br />
* The high-low drive gear selector behind the headstock is incorrectly labelled and differs from the manual: low gear (which we normally use) is with the lever towards the tailstock. ''I suspect that the gears in the headstock were refitted the wrong way round when it was upgraded to metal gears.''<br />
<br />
: ''ToDo: Get it reassembled the right way round during the spindle bearing upgrade!''<br />
<br />
===Carriage lock fouls top slide===<br />
* The T handscrew has been replaced with a M5 hex headed bolt, to permit access when the top slide is over it. An 1/4" drive 8mm socket is usually left on it, but needs to be removed when the full cross slide travel is needed. The small (4 jaw) chuck key is near enough 1/4" to use for it. If you need to (un)lock it while the compound is over it, you'll need an 8mm spanner. ''The [https://www.amadeal.co.uk/acatalog/Mini-Lathe-Carriage-Lock-463.html Amadeal lock screw] is in the spares tin as it was too high and fouled the compound slide.''<br />
<br />
===Tailstock locking lever loose===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock - See full image for key to screws]]<br />
* Diagnosed and fixed 10/1/2023 - In the base of the upper section of the tailstock, there are two dog tip set screws that engage with locating grooves in the counter-rotating shafts carrying the eccentric locking cams. They'd backed off, probably due to vibration. They need to be tightened till they bottom out in the groove, making sure they are '''in''' the groove, backed off half a turn so the shafts can turn easily, and locked in place. There's no facility to do so, so reassemble with weak threadlocker. Unfortunately to get to them you have to remove the tailstock base slide, which is held on by the pressure of four adjusting grub screws, which all need backing off, and one socket headed bolt from underneath so full tailstock realignment is required after reassembly, which even for a rough alignment is tedious.<br />
: <s>The tailstock locking lever is loose and can be pulled out on its axis. It works OK when fully pushed home but needs investigating. ''I tightened the grub screw as the lever was coming off its shaft, but the whole shaft pushes/pulls in and out. It works OK fully pushed in, but it seems something that is meant to retain it has failed inside the tailstock base.</s><br />
<br />
===Gear alignment issues===<br />
* Change gear alignment is poor. I've currently got a gapped washer (to clear the key) packing out the A shaft so the gears line up, but this reduces the key's engagement so is problematic due to the high loading if the gears are set up for coarser threads. <s>Also I need to turn down some penny washers to slightly less than the root diameter of the metal 20T pinions, as gear retaining washers.</s> ''The gear retaining washers for A gear and B-C stub shaft are now done, turned down to slightly under 16 mm dia. Spares in the change gear tin. ToDo: The D (leadscrew) washer requires a larger center hole, so make two more with that hole.'' <br />
<br />
===Saddle gibs loose===<br />
* Fixed 11/04/2023: I took the apron off for access (and to clean the carriage handwheel gears), and found the front sheer plate screws were completely loose. I've snugged them up some and set the opposing grub screws and got a lot of the slop out. I've re-checked the front ones, and taken up the slop in the rear ones - Unfortunately it wasn't possible to get carriage movement to have an even 'feel' over its whole travel, and its noticeably tighter near the tailstock. If light hand pressure on the side of the unlocked carriage can cause movement (with the half-nuts open), its time to readjust them again, though it should be possible to move the carriage with a firm push. <s>The saddle gibs (actually the sheer plates) were too loose, to the point that engaging a slightly stiff threading dial could cause it to self-feed, an obvious crash hazard if working near the chuck or a step in the work.</s><br />
<br />
''N.B. the lefthand front opposing grubscrew is short, (fully recessed) and unlike the others does *NOT* have a locking nut as it must clear the traverse pinion. A wrap of PTFE tape provides enough friction to keep it in place, though possibly a bit of nylon fishing line down its hole would be better.''<br />
<br />
===Excessive cross-slide backlash===<br />
* ''Fixed 21/11/2023.'' Originally, back in October 2023, The cross-slide screw had excessive backlash (nearly three turns), which increases the risk of loosing track of the cut depth when cutting steps, and during threading operations. If you ended up off by a turn too far in, a crash would be the most likely outcome.<br />
: The original excessive backlash was traced to loose cross-slide screw nut mountings. The nut has two socket headed cap screws pulling up, one either end, accessible from the top of the cross-slide, which control the tilt of the nut to take up backlash in the nut, and an opposing grub screw pressing down on the center of the nut to make it longitudinally rigid. Snugging up the grub screw reduced the backlash to 10 divisions or so, or 0.25 mm. A year later, the backlash had increased to one turn due to the cross-slide nut mounting screws working loose again.<br />
<br />
: 07/11/2023: I investigated further: It is difficult to get the cross-slide nut aligned correctly as it must be at the same height as the screw which is constrained by the bearing surfaces in the bracket. With the cross-slide almost at the front limit of its travel, I removed the screw and set the nut as level as possible and visually centered in the bore, then re-fitted the bracket and screw, then adjusted the tilt till it turned freely through the backlash. I then tilted it up at the front till some drag was felt to minimise the backlash and tightened the screws to lock it in place balancing them to maintain the same feel as I tightened them. The result was 7 divisions of backlash, acceptable but not great. During normal turning operations, the load on the nut is tension on the front screw and pressure on the grubscrew, so if it slackens again due to vibration from chatter, odds are it will be the rear screw that's loosened.<br />
<br />
: 16/11/2023 - 21/11/2023: The backlash had crept back up to 11 divisions (0.275 mm). We don't have any >14 mm brass stock (or even near that) so I tried making the shim washer out of aluminium. I was shooting for 0.24 mm but due to poor technique got 0.28 mm. No good - locked solid. I lapped it down and tried it till I got it down to 0.20 mm which gave about 3 divisions backlash - good enough, but the screw was too tight due to the shim washer not being bevelled at its outer edge resulting in it cupping in its seat. Filing a bevel round the OD and re-lapping it resulted in a 3 - 4 divisions of backlash. Its a little mushy due to the washer having been kinked removing it, so ideally a new (brass) washer should be made. <br />
<br />
* Further reduction of backlash: https://youtu.be/Wu_tI29JL2Y?t=163 <br />
: Brass tinned with Pb-free solder to form a white metal bearing surface should work at least as well as the bronze used in the video. The shim washer needs to be 10.2mm ID, with a full thickness bevel on a 14 mm OD. It isn't necessary to remove the lead screw from the cross slide, as the washer can be fitted in-situ with only the bracket removed.<br />
<br />
===3 Jaw chuck didn't mount properly===<br />
* Fixed 7/4/2023 by grinding the spindle nose lip. The three jaw chuck can now be installed and removed by hand with no hammering. A test bar in it now has only 2 thou runout (TIR) at the chuck.<br />
: <s>The three jaw chuck and the faceplate aren't seating properly on the spindle nose. Its too tight on the register diameter of the lip. This results in grossly excessive runout, and also makes this chuck and the faceplate a PITA to fit or remove.</s><br />
: ''The spindle nose had been abused with a hammer (before my time) which mushroomed it and may have brinelled its bearings. See '''Excessive Runout''' and '''Spindle bearings''' above.''<br />
<br />
== Manuals, Books and other resources ==<br />
=== Manuals ===<br />
The [https://wiki.richmondmakerlabs.uk/images/a/a3/Lathe_InductionNotes.pdf RML CJ18A Mini-Lathe Induction Notes]. Your mandatory Lathe Induction will cover most of this but its good to be able to refer back to it.<br />
<br />
Official [https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Amadeal CJ18A Manual], or paper copy (less complete) kept on shelf above lathe.<br />
<br />
The [https://www.chesterhobbystore.com/wp-content/uploads/2022/11/Conquest-Super-Lathe.pdf Conquest Super Lathe manual] is considerably better than the Amadeal manual and is for a near-identical machine.<br />
<br />
The [https://littlemachineshop.com/images/gallery/info/minilatheusersguide.pdf Mini Lathe User’s Guide] from LittleMachineShop.com is even more comprehensive, going into its usage in some detail, with a proper TOC, and covers both US and Metric versions of Realbull Mini-lathes. ''The only fly in the ointment is the threading section assumes a US lead screw so change gear selections and threading dial divisions will not be correct for our lathe.''<br />
<br />
[https://www.arceurotrade.co.uk/machineguides/C3-Mini-Lathe-Dismantling-and-Reassembly-Guide.pdf Sieg C3 Mini-lathe Dismantling and Reassembly Guide] "A picture story book to help you dismantle and reassemble your Sieg C3 Mini-Lathe" ''It is similar enough to ours to serve as a maintenance guide, except for the electronics, spindle drive and other headstock innards.<br />
<br />
The motor controller is a clone of a [https://acim.nidec.com/drives/kbelectronics/-/media/kbelectronics/documents/dc-drives/manuals/kbic_manual.ashx?la=en KBIC® SCR DC Motor Speed Control]<br />
<br />
=== Books ===<br />
'''Metal Turning on the Lathe''', by David A Clark, Crowood Metalworking Guides, ISBN-13: 978-1847975232 [https://www.amazon.co.uk/gp/product/B00E78RKIG Kindle Edition (£8.99)]. ''A 'free' epub can be googled for, *NOT* linked here due to dubious legality.''<br />
<br />
'''[https://archive.org/details/03screwcuttinginthelathe Screwcutting In The Lathe]''', by Martin Cleeve (a pen-name of Kenneth C Hart), Workshop Practice series #3, ISBN-13: 9780852428382<br />
<br />
'''[https://archive.org/details/15workholdinginthelathe Workholding in the Lathe]''', by 'Tubal Cain' (a pen-name of Tom Walsh), Workshop Practice series #15, Argus Books, ISBN-10: 0852429088<br />
<br />
'''[https://archive.org/details/20metalworkandmachininghintsandtips Metalwork and Machining Hints and Tips]''', by Ian Bradley, Workshop Practice series #20, ISBN-13: 9780852429471<br />
<br />
'''[https://archive.org/details/38toolandcuttersharpening Tool and Cutter Sharpening]''', by Harold Hall, Workshop Practice series #38, ISBN-13: 9781854862419<br />
<br />
'''[https://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpaperT204.pdf Cutting Fluids]''', by EC Bingham, NIST Tech. Paper No. 204, 1921<br />
<br />
=== WWW resources ===<br />
==== Mini-lathe Specific ====<br />
There's a *LOT* of mini-lathe info online. Notable sites include:<br />
* http://www.mini-lathe.com/ - A major Realbull/Sieg mini-lathe resource.<br />
* http://mikesworkshop.weebly.com/lathe-modifications.html - many mods including carriage DRO autostop, and variable speed leadscrew motor drive, cross-slide motor drive, etc. He also has a page with a bunch of accessories, toolholders etc. - http://mikesworkshop.weebly.com/lathe-accessories-and-tooling.html<br />
* http://andysmachines.weebly.com/variable-speed-controls.html - Scroll down to the 'UPDATE' section for the schematic of a very similar SCR speed control board. It also has the schematic for an earlier version of the Auxiliary Control Board (aka: 'Filter' board).<br />
<br />
==== Forums ====<br />
''with publicly accessible archives''<br />
* https://groups.io/g/7x12MiniLathe - Mini-lathe specific, active<br />
* https://www.hobby-machinist.com/forums/mini-lathe-mini-mill-information.220/ - active<br />
==== Youtube Playlists & Videos ====<br />
* Blondihacks: [https://www.youtube.com/playlist?list=PLY67-4BrEae9Ad91LPRIhcLJM9fO-HJyN Lathe Skills] (playlist) - "This is an educational series to help you learn to use your metal lathe. Watch them in order for best results! Satisfaction not guaranteed, especially if you're a cranky sort of person."<br />
* Frank Hoose (Minilathe.com) has a couple of relevant Youtube playlists:<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn7ON0jGM5UbM-KZDT56MOIp Mini Lathe Operations]<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn4nGRZaVq3wTOlvZNOmdAZ2 Mini Lathe Overview]<br />
<br />
==== General Machining ====<br />
* https://www.machiningdoctor.com/ - "THE #1 MACHINING TECHNICAL HUB"<br />
<br />
==Projects==<br />
[[File:VESA mount.jpg|thumb|Machined VESA mounting plate (left) and plate from Dell monitor stand it must match (right). The translucent washer shows the size of the original center hole.]]<br />
* My first faceplate project was boring out the center hole in a VESA mounting plate to adapt it to fit onto a surplus Dell 1708FP monitor stand. The part was centered using the tailstock dead center engaging with its original center hole. I clamped the part with studs and penny washers on the driving side of two opposite corners, with cap screws in the next slot round to trap the corners under the clamping washers, then withdrew the tailstock and dead center. After machining out the bore, I used the tip of the tool, rotating the chuck by hand, to scribe a circle for laying out the bolt holes. I finished off laying out and drilling the bolt and locating holes by hand at home, fitted it to the stand, and mounted the 2nd hand LG 24" widescreen monitor.<br />
<br />
* Another ultimately unsuccessful project was fly cutting aluminum flat bar to thickness to make custom shims for the set of carbide insert tools, for the four way toolpost. The 8 mm shank tools need ~2.5 mm shim stacks, and the 6 mm shank tools need ~4.5 mm shim stacks. Ideally I'd machine single shims, but the only stock I've got handy cleans up to only 3.2mm, and some fine shimming may be needed to fine-tune the tool height.<br />
<br />
: After sorting out the clamps so they were no longer twisting the aluminum flat bar stock, and switching to the short 45° turning SCMT06204 insert tool in the four way toolpost, to improve rigidity and get a well controlled tip radius, the finish was much improved. I'm still having problems getting an even thickness and am getting approx. 0.05mm variation, I suspect due to the aluminium bar stock distorting due to internal stresses as its surface is cut away. ''ToDo: try supergluing the stock to the faceplate before clamping to further reduce chatter and stop the warping.''<br />
: Looking back on this project a year later, its fairly obvious that the thickness variation was probably due to faceplate surface runout due to the damaged spindle nose.<br />
<br />
* Raphael has been working on a steel rocket nozzle with some assistance from myself. We have set up the rough cut chunk of ~ 50mm steel bar, faced both ends (to 50mm length) and turned the OD to 49mm to clean it up. Its going to need through drilling, probably some boring, and quite a bit of detail work on the OD. It will then need to be transferred to a jig in the drill press vice to allow a pattern of angled traverse holes to be drilled with acceptable accuracy.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_Lathe_Notes&diff=17589Ian M's Lathe Notes2023-11-23T10:30:37Z<p>IanM: /* Excessive cross-slide backlash */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br />
<br />
''Currently these notes are semi-organized and non-authoritative. As I become more experienced with the RML CJ18A mini-lathe, I'm cleaning up, extending and reorganising them. Some lathe operating experience is assumed. If in doubt, '''*ASK*''' me, Andy H<sup>*</sup> , Jonathan H or another experienced minilathe operator!<br />
<br />
''* Andy H should be asked (for an authoritative answer) any questions involving RML usage policies or acquiring tooling or materials through RML.''<br />
<br />
== The Lathe ==<br />
Our Facilities page [[Facilities#Lathe|has]]:<br />
<blockquote><br />
'''Lathe'''<br />
[[File: Lathe2.jpg |200px|right | Lathe]]<br />
In the kitchen. <br />
<br />
Marked as a CJ18A Mini-Lathe from [[https://www.amadeal.co.uk/acatalog/CJ18A-Mini-Lathe-7x14-Machine-100mm-3jaw-Metric-With-Metal-Gears-AMA_LA_CJ18_M_3_MGRB.html Amadeal]]<br />
[[https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Manual]] <br />
<br />
[[Media:Lathe InductionNotes.pdf| Induction Document]]<br />
<br />
Possible upgrades:<br />
*https://www.youtube.com/watch?v=GwT-JQLbNPA<br />
<br />
''Please do not use the lathe until you have received induction'' <br />
<br clear=all><br />
</blockquote><br />
Its a Chinese import 7x14 mini-lathe. The 7x14 refers to the maximum diameter and length of work, in inches and is only a theoretical measure of the working envelope as you loose length to the chuck + any tailstock tooling, and the diameter is over the bed, not the cross-slide. See actual specifications below. <br />
<br />
Most if not all Chinese 7x10 to 7x16 mini-lathes seem to be remarkably similar (not uncommon with Chinese products due to [https://www.bunniestudios.com/blog/?p=284 Shanzhai (山寨)] )<br />
and the OEM of our Amadeal CJ18A Mini-Lathe was probably [https://www.made-in-china.com/showroom/cheap-lathe Yangzhou Realbull Machinery Co. Ltd]. Very similar lathes are also made by [https://www.siegind.com/lathe-machine.html Sieg], but their lathes tend to be slightly less sophisticated than the equivalent Realbull models.<br />
<br />
''N.B. Many Sieg parts are known to have slight but critical differences from Realbull parts, so '''DON'T''' order Sieg spares for a Realbull lathe!<br />
<br />
== Key Specifications ==<br />
Amadeal says the CJ18A Mini-Lathe is a 7x14 model with:<br />
<blockquote><br />
* Power 550 W<br />
* Distance between centres : 350 mm<br />
* Swing Over Bed: 180 mm<br />
* Swing Over Cross Slide: 110 mm<br />
* Taper: MT3<br />
* Tailstock Taper: MT2<br />
* Chuck diameter: 100 mm<br />
* Spindle Speed: 50 - 2500 rpm ''(with digital readout)''<br />
* Spindle Bore: 20 mm<br />
* Cross slide Travel: 65 mm<br />
* Range of Metric Threads: 0.5 - 2.5mm.<br />
</blockquote><br />
* The lead screw is metric, pitch 1.5 mm.<br />
* The spindle center is 90.6 mm above the flat of the bed (measured).<br />
<br />
Even though the compound and cross slide handwheels appear to be calibrated in thousandths of an inch, as ours is a metric machine, they only approximate that. One turn of a slide handwheel is 1mm advance, and they have 40 divisions, so each division is 0.025 mm, (approx. 0.984 [https://en.wikipedia.org/wiki/Thousandth_of_an_inch thou]). Similarly, the tailstock quill advances 1.25 mm per handwheel turn, which has 50 division dial, giving the same 0.025 mm divisions, but only 4 turns per 5 mm. The carriage handwheel is awkward - it moves approx. 19.2 mm per turn, and doesn't have a dial scale.<br />
<br />
== Notable Accessories ==<br />
We have:<br />
* [https://www.amadeal.co.uk/acatalog/160mm-Face-Plate-for-the-4-Mini-lathe-AMA_AC_CJ18A_FP160RB.html#SID=129 160 mm (6 1/4") Faceplate]<br />
* 100 mm (4") three jaw self-centering chuck (OEM standard) 22.5mm bore, with inside and outside jaw sets<br />
* 100 mm (4") four jaw (independent) chuck with reversible jaws (8 TPI screws)<br />
* Tailstock drill chuck (max. 13 mm dia.)<br />
* Live center for tailstock (+ OEM fixed center) <br />
* Four way Tool Post (OEM Standard)<br />
* [https://www.amadeal.co.uk/acatalog/Quick_Change_Tool_Post_for_the_mini-lathe.html Quick Change Tool Post] + 3 tool holders<br />
* [https://www.amadeal.co.uk/acatalog/Fixed-Steady-for-Mini-Lathes-AMA_AC_CJ18A_FSRB.html#SID=145 Fixed Steady Rest]<br />
* [https://www.amadeal.co.uk/acatalog/Travelling-Rest-for-Mini-Lathes-AMA_AC_CJ18_TSRB.html#SID=144 Travelling Steady Rest]<br />
<br />
''You'll find all of the above on the shelf above the lathe, with the accessories in the wooden box, apart from the steadies, which live next to it. Change gears, spare parts, and most cutting tool tips/blanks are in labelled white rectangular tins behind the lathe.''<br />
=== Measuring Tools ===<br />
We have:<br />
* Various dial indicators - the one with the adjustable magnetic base stand is the most convenient for most lathe setup work.<br />
* 25mm micrometer (in little grey case)<br />
* Grey case containing set of measurement tools including dial calipers, micrometer, steel rule (metric & inch), engineers square, and a fish-tail gauge<br />
<br />
''We currently lack''<br />
* ''A tool height setting gauge''<br />
<br />
=== Hand Tools ===<br />
Some common tools needed for normal use are kept with the lathe, in or attached to the wooden accessories box:<br />
* 2 mm Allen key - adjusting cross-slide and compound gibs<br />
* 4 mm Allen key - quick change toolholder tool clamping screws + height adjust, tightening dials<br />
* 5 mm Allen key - four way toolpost tool clamping screws, engaging/disengaging threading indicator<br />
* 6 mm Allen key - locking/unlocking quick change toolholder<br />
* 8 mm spanner - locking carriage when 8 mm socket can't be used, locking gib adjuster nuts <br />
* 13 mm spanner - changing chucks, locking steady rest jaws<br />
* Very long needle nose pliers - for grabbing swarf safely, holding one end of emery cloth safely so you can keep your fingers away from the jaws, and extricating small objects from awkward places.<br />
<br />
== Change Gears ==<br />
[[File:BC puller 1.jpg|thumb|Custom puller for B-C stub shaft]] [[File:BC puller 2.jpg|thumb|Pulling the B-C stub shaft]]<br />
See "Conquest Super Lathe" manual ([[#Manuals|below]]), section '''4.7 Change Gears''', PDF pages 28-29, but see below for mesh adjustment. The LittleMachineShop.com "Mini Lathe User’s Guide" (also below) section '''Threading''' gives a far better explanation, with pictures and diagrams, but its for a lathe with a US 1/16 inch pitch leadscrew, not a metric 1.5 mm pitch one like ours, so you *MUST* ignore all the tables in that section, replacing them with metric mini-lathe (with 1.5 mm pitch leadscrew) equivalents. <br />
<br />
We have the following tooth count gears: 20,20, 30, 35, 40,40, 45, 50,50, 60,60, 80,80<br />
which consist of the OEM power feed gears + the metric change gear set. Apart from the metal 20 tooth pinions, they are all plastic, probably Delrin if the molded in 'POM' marking can be trusted, but possibly plain Nylon 6, and are metric Module 1.<br />
<br />
If we wanted to add the capability to cut US/Imperial threads we'd need to buy additional 55, 57 and 65 tooth gears, and possibly a 21 tooth metal pinion.<br />
<br />
CGTK's [https://www.cgtk.co.uk/metalwork/calculators/changegears/minilathe?gears1=20,20,30,35,40,40,45&gears2=50,50,60,60,80,80&gears3= Change Gear Calculator] ''(link preloaded with our gear list)'' is useful if you don't want to calculate the ratios from first principles. Not all suggested combos will physically fit.<br />
<br />
* Take care *NOT* to loose the keys in the A and D shaft keyways - turn each shaft till the keyway is up before removing the gear. <br />
* The B and C gears are coupled by a hollow stub shaft (with an integral key), which is so tight in the gears it has to be pressed or driven out - I've made a puller just for this task, kept in the change gears tin.<br />
* The center of the B-C stub shaft *MUST* be lubricated where it runs on its pin on the change gear banjo bracket, with grease or heavy oil. ''Seizure of the stub shaft due to running dry is a frequent cause of catastrophic mini-lathe geartrain failures!''<br />
* Don't get oil on the change gears as it can cause plastic gears to crack. Only PTFE drylube or plastic compatible white grease should be used on their teeth. <br />
* Adjust the B-C pin position in the straight slot first to set the C to D gear mesh, tighten its nut, then swing the whole banjo about the D shaft boss to set the A to B mesh, and finally tighten the banjo clamping nut.<br />
* Check both gear meshes have running clearance by turning the chuck by hand enough to complete one full turn of the leadscrew, and by attempting to turn the intermediate gear(s) to assess backlash, If excessive resistance is felt or if there's significant backlash, readjust the gears. If you have difficulty judging the mesh, a strip of 80 gsm copier paper (approx. 0.1 mm thick) wound into the meshing teeth before tightening the stud or banjo will give appropriate clearance once removed. Once setup, check the gears run quietly under power.<br />
* If the sum of the tooth counts C+D is the same as for the ones you just removed and they were correctly meshed, you don't need to move the stub shaft pin. If A+B is <u>also</u> the same, you don't need to move the banjo. e.g. If it was set up for 16:1 reduction power feed, 1 mm (40:60 - 50:50) for M6 and 1.5 mm (e.g. 40:60:40) for M10 pitches can thus be achieved by only swapping gears. <br />
<br />
''The change gears, puller, etc. and a box spanner for the banjo nut are kept in a white rectangular tin behind the lathe.''<br />
<br />
=== Power Feed ===<br />
When used for turning with power feed, the change gears should be set for a 16:1 reduction (A:20 : B:80 - C:20 : D:80) using the pair of small metal 20 tooth pinions and the 80 tooth plastic gears (largest in set), for a feed of 0.09375 mm per turn (1.5 mm/16). Unless continuing your threading project the next session, please re-fit the 16:1 power feed set after threading so the power feed is ready for use. <br />
<br />
* *ALWAYS* leave the feed direction selector lever in its neutral (no feed) position, and the half-nuts open after use.<br />
* *ALWAYS* check the carriage lock is disengaged before engaging power feed. Unlock the carriage after use. <br />
<br />
=== Threading Dial ===<br />
The threading dial is an aid to re-engaging the half-nuts at the right moment so the tool will retrace its previous path cutting deeper, rather than offsetting axially some fraction of the thread pitch and ruining your work. Its based on the concept of the lowest integer multiples of the leadscrew and thread ''(being cut)'' pitches that exactly match, but for mechanical simplicity it only covers certain selected multiples of the leadscrew pitch.<br />
<br />
We have a choice of three pinion gears:<br />
{| class=wikitable<br />
|+ Threading dial Pinion Gears<br />
|-<br />
! Teeth !! Colour Dot !! Usable lines !! OD gear !! Dist. per turn<br />
|-<br />
| 14 || Red || 1,7 || 7.51 mm || 21 mm<br />
|-<br />
| 15 || Orange || 1,5,9 || 8.05 mm || 22.5 mm<br />
|-<br />
| 16 || Green || 1,4,7,10 || 8.37 mm || 24 mm (2 mm/div)<br />
|}<br />
They are now colour coded, with a paint dot on the gear end face ''(the only non-wear surface)''. The 16 tooth one is normally left on the lathe, but disengaged when not threading to minimise wear on the lead screw. The others are kept in the Change Gear tin.<br />
<br />
There's a threading dial 'pickup' calculator here: https://www.cgtk.co.uk/metalwork/calculators/threaddialindicator <br />
<br />
Initially select ''Lathe:'' '''Custom''', and enter the following below:<br />
* ''Units:'' '''Metric'''<br />
* ''Lead Screw Pitch (mm):'' '''1.5'''<br />
* ''Thread Dial Indicator Gear Teeth:'' '''16,15,14''' <br />
* ''Lines on Thread Dial Indicator:'' '''12''' <br />
* ''Line Marking:'' '''Every Line Numbered'''<br />
Note the teeth list is entered in reverse order so the resulting table highlights any required pinion changes.<br />
<br />
N.B. The dial is only friction clamped to the pinion by its center screw. If you have any reason to suspect it may not be properly aligned: <br />
# With the power off and the carriage unlocked, engage the feed direction lever upwards. You'll probably need to turn the chuck by hand to get it to engage.<br />
# If the threading indicator isn't already engaged, loosen the threading dial support block bolt, pivot the block to engage the pinion with the leadscrew and retighten the bolt.<br />
# Engage the half nuts, again turning the chuck by hand till they drop in. <br />
# Turn the chuck a couple of turns, top towards you to take up any backlash, then lock the carriage, taking care not to push it left while locking it.<br />
# Loosen the screw securing the dial to the pinion.<br />
# Align the '1' line of the dial with the index line, by rotating the dial clockwise, then retighten the screw.<br />
# Don't forget to disengage half-nuts and unlock the carriage!<br />
<br />
The above instructions should result in the half-nuts engaging cleanly when exactly on any valid line when threading towards the headstock. If it is required to thread away from the headstock, there will be a slight offset from the line due to backlash between the spindle gear and leadscrew, so engage slightly early.<br />
<br />
Changing the pinion:<br />
# Loosen the threading dial support block bolt and disengage from the leadscrew.<br />
# Undo dial center screw, and remove it and the dial, dropping the old pinion out the bottom.<br />
# Oil the shaft of the new pinion with a drop of light oil and insert it from below, gear end down.<br />
# Refit dial and screw.<br />
# Check the dial and pinion turn freely with minimal resistance.<br />
# Align as above.<br />
<br />
== Tailstock and Steadies ==<br />
These are mostly used to support long work ''(long with respect to its diameter)'' to improve rigidity, increasing accuracy and reducing chatter. The Tailstock quill is also used with a drill chuck for drilling.<br />
=== Tailstock ===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock base]]<br />
The tailstock can be offset to turn shallow tapers between centers. We don't currently have the accessories to turn between centers, namely <s>a MT3 dead center for the spindle, or</s> any drive dogs for the work. Also realigning the tailstock after turning a taper can be a PITA. The photo shows the tailstock adjusting screw locations ''(C - Lateral, and D - Skew)'' and the block on the baseplate they engage with. Adjustments can only take effect when the tailstock locking lever is eased to take the pressure off the baseplate. As we don't have a MT3 center, one has to turn a fresh point on a test workpiece for a rough tailstock alignment reference. Fine alignment, to avoid inadvertent taper turning, can be done by mounting a long precision ground bar between the chuck (or preferably a center in the spindle), and a dead center in the tailstock and sweeping it with a dial indicator on the carriage. Finally a test cut should be taken at either end of a bar between centers, and the diameters checked with a micrometer. Assuming the bed has previously been properly levelled and shimmed to take out twist ''(not the case at RML as we don't have it bolted down)'', any remaining difference in diameter will be double the tailstock offset, smaller at the tailstock being offset towards the front. Fine adjustment cant be achieved by jacking with the screws, its best to ease the adjusting screws, bump the tailstock into alignment then take up the screws again, checking the alignment is maintained when the tailstock is unlocked and relocked. There is no vertical adjustment, though shims can be added between the tailstock and its base.<br />
<br />
==== Tailstock Quill ====<br />
There is a metric/imperial scale on the top of the quill, read against the end of the tailstock, for depth measurement when drilling. The tailstock quill has a 1.25 mm pitch thread and a 50 division dial. Each division is therefore 0.025 mm, and it only takes 4 full turns of the handwheel to move the quill 5 mm. <br />
<br />
To eject MT2 taper tooling and centers from the tailstock, wind the quill all the way in.<br />
<br />
N.B. The quill anti-rotation pin (dog-tip setscrew + locking nut in top of tailstock near to the quill lock) is only M5. It will sheer if a large diameter drill jams in the work. Please back it out clear of its keyway if using large drills, and use alternative methods of preventing chuck rotation. To re-engage it, crank the quill out till you can see the keyway, align it with the screw and screw in the screw till it gently bottoms out, then back it off a quarter turn. Try twisting the quill to check its properly engaged, then tighten the locking nut gently to hold the screw in position clear of the bottom of the keyway.<br />
<br />
=== Steady Rests ===<br />
We have two, both with brass tips that must be kept lubricated during use.<br />
<br />
The fixed steady mounts on the ways, and is most useful when turning longer work that wont fit through the spindle bore. Adjustment is critical, and the surface the tips run on must be smooth and concentric, as any misalignment that forces the work off center will result in the work wobbling in the chuck, marring it, with a high risk of it becoming un-chucked, which can be dangerous at speed.<br />
<br />
The travelling steady mounts to the headstock side of the carriage to locally resist the deflection of thin long work, due to the cutting forces. It only has two tips, to resist climb, and deflection away from the tool, and requires readjustment after every cutting pass.<br />
<br />
== Tooling and Tool Holders ==<br />
'''Key dimensional data:'''<br />
* The quick change holders accept up to 10 mm shank tools. <br />
* The four way toolpost has 50 mm long sides, a seat width of 15 mm and can clamp tools of up to 5/8" (15.875 mm) shank ''(check this)'', but the slot base is only 10.4 mm below the spindle center so cannot be used with >10 mm shank tooling unless it has a dropped tip. Large tooling with a centered tip is also problematic as you run out of height above the shank when trying to shim to match the spindle center height. <br />
<br />
===Quick Change Toolpost===<br />
I've got the quick change toolpost and toolholders setup for mostly easy use. The three toolholders came with cantilever height setting arms which historically haven't been installed as the supplied fixing screws were too short. That's all now sorted out and a HSS RH turning tool and a HSS hand-ground grooving/parting-off tool are now mounted in two of the holders and set to height. The third is kept free for other tools. <br />
<br />
The quick change toolpost has been modified with a spring to press the dovetail clamp outwards and help stop it twisting or flopping about to ease toolholder fitting and removal. The dovetail clamp (socket headed screw on toolpost side opposite dovetail) feels a bit stiffer than before, but will take less than half a turn to go from open (with the toolholder lifting out or dropping in easily) to fully clamped. As there is so much less clearance in the open position you should no longer need to wiggle the toolholder while clamping it to get a consistent height. If the dovetail clamp ever gets misaligned, twist it straight by eye, slacken off a bit further than usual to get a toolholder on, clamp it to align the dovetail then release, reseat the toolholder and re-clamp to ensure its at its preset height. You cant adjust the height by 'jacking' with the height screw due to its offset leverage. Instead, back off the height screw and hold the toolholder at the desired height while locking the dovetail clamp, then adjust the height screw (and locking nut) to hold it there, then check it doesnt change height significantly when you unclamp and reclamp the dovetail. <br />
<br />
Unfortunately the OEM height setting screws foul the toolpost locking nut handle. Currently, if you need to swap toolposts you will have to first remove the quick-change tool holder from the post. There is enough nut handle swing to allow the quick change toolpost to be unclamped and rotated to fine set the tool angle without removing the toolholder. It also seems the mating surfaces may be slightly out of square, as if you rotate the toolpost 90° or 180°, the nut swing may be insufficient to re-clamp it without removing the toolholder to do so. Add a M10 washer under the locking nut if the handle ends up pointing in an undesirable direction! A thin M10 washer is kept with the toolpost collar for this purpose, and will shift the handle position by about a third of a turn. <br />
<br />
''ToDo: Make a taller nut of a similar pattern, to clear the height setting screws.''<br />
<br />
===Four Way Toolpost===<br />
The OEM four way toolpost is significantly more rigid than the quick change toolpost + holders because it has fewer and thicker parts and less overhang. Therefore the four way toolpost should be used when using carbide tooling. It requires shimming under the tool to set the tip height to the spindle center height - see below. The tool shanks are mostly significantly less than 15 mm wide, so need to be centered under its clamping screws, tempting as it is push the shank in for full side contact with the toolpost. If possible clamp the shank with all three screws not just two.<br />
<br />
==== Shimming ====<br />
We typically only mount up to two tools, and want maximum rigidity, so use 50 mm x 15 mm shims, (the full seat area), preferably with deburred edges and radiused corners so they aren't a hazard to the operator.<br />
<br />
We have pre-cut and marked shims of the following thicknesses: <br />
* 1x 3.23 mm, 2.42 mm, 1.56 mm, 0.32 mm, and 0.25 mm<br />
* 2x 1.00 mm, 0.77 mm, 0.12 mm, 0.11 mm, 0.10 mm and 0.05 mm<br />
* 4x 0.53 mm<br />
<br />
Our shims are mostly found materials (hence the awkward thicknesses) and are mostly a mixture of aluminium and steel, with a couple of GRP ones. The toolpost seat '''<u>must be absolutely clean</u>''' to avoid embedding debris in the aluminium or GRP shims, to get a consistent height and avoid tilting the tool - wipe it every time you change a tool! Put the thin shims at the bottom of the stack to avoid the tool shank edges creasing them. Shims are kept in a little yellow plastic box with a clear lid, near the carbide tools case.<br />
<br />
I made a tool height setting gauge (T shaped black acrylic with steps in its sides) which can be used to check the tool tip height matches the spindle center height using either the flat of the ways or the saddle as a reference. The tool tip should just fit under the lip of the appropriate step, with the T arms across the ways flats or on the saddle. It is kept in the box with the carbide insert tools.<br />
<br />
''ToDo:'' <br />
<br />
* ''Cut more shims neatly, mark them with their thickness.''<br />
* <s>''Do test cuts and start noting shim stack-ups for various tools.''</s><br />
* ''Organise shim storage!''<br />
<br />
=== HSS Tools ===<br />
[[File:Tool Bit Geometry.jpeg|thumb|Single point cutting tool geometry]]<br />
Our HSS tools are made from 8 mm square bar stock, hand-ground to tip profile in-house. See LittleMachineShop's [https://littlemachineshop.com/images/gallery/instructions/grindingtoolbits.pdf Grinding Tool Bits] notes. <br />
<br />
I've installed our usual HSS LH turning and parting off tools in two of the quick change holders and set the heights correctly. There are a couple of other HSS tools or tool blanks knocking about. Taking heavy cuts turning steel (even with good cutting oil) blunts HSS tools fairly quickly, which are time-consuming to re-sharpen nicely without a dedicated tool & cutter grinder with appropriate jigs. Its worth noting that the usual 'speeds & feeds' tables are commonly based on surface speeds expected to give a half hour (active cutting) tool life before resharpening.<br />
<br />
I touched up the LH turning tool by lapping on wet & dry (silicon carbide) paper on glass (Aka: [https://en.wikipedia.org/wiki/Scary_sharp 'Scary Sharp']) working upwards through the grits 200, 400, 600 and finally 1000, initially 'bluing' the surfaces to be lapped with a marker pen to see which areas needed taking down more. The end of the tool was significantly uneven so I touched that up freehand on the bench grinder to flatten it when it became apparent that 200 grit lapping wasn't cutting where it needed to. There was an existing micro-bevel on the leading side, which I kept. Finally I 'dubbed' the leading corner vertical edge on the 1000 grit to give it a very slight nose radius. A test cut on brass gave a very nice finish when turning.<br />
<br />
''Ian B has purchased some spare 8mm HSS tool blanks - talk to a lathe trainer if your proposed lathe work needs custom ground HSS tooling.'''<br />
<br />
=== Brazed Tungsten Carbide Tools ===<br />
Somewhat of a half-way house between hand ground HSS tooling and insert tooling with the disadvantages of both and some more besides - e.g. they are much harder to sharpen. So why do we bother? Some tool geometries would be awkward and tedious to hand grind, and Chinese import brazed carbide tooling is about half the price of similar HSS tooling, and far more readily available. Also, for space constrained tooling like boring bars, if you want carbide, for insert tooling, the size of the insert and its clamping seriously limits the minimum hole diameter you can work in. I have purchased a set of 3/8" shank brazed carbide tipped boring bars, but we currently cant sharpen them, due to lack of a diamond grinding wheel. <br />
<br />
=== Tungsten Carbide Insert Tools===<br />
Decoding ISO insert tooling part numbers: https://www.cutwel.co.uk/blog/learn-the-turning-tool-iso-code-system<br />
[[File:Carbide set.jpg|800px|thumb|left|Our set of Tungsten carbide insert lathe tools (before the new inserts were fitted)]]<br />
<br />
{| class=wikitable<br />
|+ Tools, left to right, (+ last across top):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| SSKCR0610H06 || 75° through boring || SCMT06204 || Long || 6 || 6.34 || ''4.33''<br />
|-<br />
| SSSCR0610H06 || 45° deep facing, internal chamfering || SCMT06204 || Long || 6 || 6.13 || ''4.58''<br />
|-<br />
| SWUCR0610H05 || 93° boring, deep facing || WCMT050308 || Long || 6 || 6.22 || ''4.48''<br />
|-<br />
| SWGCR0810E05 || 90° RH turning & facing || WCMT050308 || Short || 8 || 8.25 || '''2.45'''<br />
|-<br />
| SSSCR0610E06 || 45° turning, chamfering || SCMT06204 || Short || 8 || 8.75 || ''1.93''<br />
|-<br />
| SSBCR0610E06 || 75° RH turning, chamfering || SCMT06204 || Short || 8 || 8.72 || ''1.98''<br />
|-<br />
| LW0810R-04 || 60° external threading || JCL15-120 || Short || 8 || 7.44 * || ''3.28''<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || 8.23 || ''2.5 ?''<br />
|-<br />
| LN0813R-04 || 60° internal threading || JCL15-120 || Long || 7.95 || 7.44 * || ''3.28''<br />
|}<br />
<br />
{| class=wikitable<br />
|+ More Tools, (loose in tin):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || ~8.5 (not in use) ||<br />
|-<br />
| [https://www.glanze.co.uk/product/glanze-12-mm-60-degree-metric-internal-threading-tool/ Glanse SIR0012K11] || 60° internal threading bar || 11IRA60 || Long || 12 dia || ??? || ???<br />
|}<br />
''Shim stack heights in bold are tested, in italic are only calculated.'' ''Tip heights marked * are with new JCL15-120I inserts. The single remaining plain JCL15-120 insert has a slightly higher tip height.''<br />
<br />
Carbide tooling typically requires two to three times more speed than HSS and at least a couple of 'thou' depth of cut for best results.<br />
<br />
Chatter can rapidly kill carbide tooling by chipping the cutting edge. To improve rigidity and reduce the risk of chatter, the cross-slide and compound gib screws need to be well adjusted so there is minimal play in the slides, tool stick-out should be minimised, the four way toolpost should be kept over the cross-slide, and the work should be kept close to the chuck (or otherwise supported by tailstock or steady rest) to avoid excessive deflection.<br />
<br />
Thermal shock is almost instant death to carbide, and when dry cutting the insert tip can run very hot, so do not add extra cutting fluid manually during the cut. Pre-apply what you need, evenly, before starting the cut.<br />
<br />
Parting off or facing to center is high risk - if the tool tip is even slightly below center or if tool or work deflection takes it below center, the work will tend to climb over the tool tip as the cut approaches center, breaking the insert. To avoid this, the tool should be shimmed slightly above center, sufficient to allow for work and tool deflection, and unless very close to the chuck, a steady should be used. Its often preferable to part to a couple of mm dia. remaining then stop and saw through the remainder. Parting off hollow parts is much lower risk.<br />
<br />
Further investigation of the Tungsten carbide insert tool height situation is not encouraging - the so-called 'set' in question does not have a consistent tip height ''(see above table)''! In a real set, the insert seats *should* be machined allowing for the insert thickness to bring all the cutting edges to the same height with respect to the shank underside. However if you place them tip to tip on a table its easy to see there is considerable height variation, so they need to be individually shimmed (or at best, one machined shim will only be right for two or three tools). At this time we don't have dedicated shim stacks for each tool.<br />
<br />
A 2.42 mm thick shim brings the SWGCR0810E05 90° RH turning & facing tool almost exactly to center height, and good results were obtained turning 1" steel pipe. However facing 50mm steel bar stock to center found it to be slightly low, leaving a fractionally under 0.05 mm 'pip' so it needs another 0.03 mm to bring it fractionally above center. Fractionally too high is generally preferable to fractionally too low, due to tool deflection, so adding an 0.05 mm shim to the stack should produce optimum results.<br />
<br />
==== Inserts ====<br />
Ian B has purchased the spare inserts we needed in sets of five. He even was able to get the CK3 parting-off inserts which had been difficult to source!<br />
<br />
Inserts used in above tool set:<br />
* 3x SCMT06204 (square, indexable) https://www.rdgtools.co.uk/acatalog/SCMT-06-Carbide-Insert.html<br />
* 2x WCMT050308 (triangular, indexable) https://www.rdgtools.co.uk/acatalog/WCMT-05-T3-08-5XTIP-8813.html<br />
* 2x JCL15-120 (60 deg threading point) https://www.rdgtools.co.uk/acatalog/X5-JCL-15-120L-THREADING-TIPS-60-DEGREE--X5-TIP---23455.html<br />
* CK3 (parting off) https://www.rdgtools.co.uk/acatalog/CK3-CARBIDE-TIPS---PARTING--BOX-OF-5PCS--9437.html<br />
<br />
Inserts used in other tools:<br />
* 1x CK3 (as above) also missing from spare parting off tool<br />
* 1x 11IRA60 in Glanse threading bar + 1x spare<br />
<br />
=== Drills ===<br />
Various sizes of center drills are kept in a plastic bag next to the wooden accessories tray. There's also a small box of 2.5 mm center drills.<br />
<br />
We have a set of 11 TiN coated HSS drill bits from 1.5 to 8 mm, (in a cylindrical plastic index box) for tailstock drilling of brass, aluminium and non-abrasive plastics. To keep them sharp enough for the precision work we expect from the lathe, please don't use them for steel or reinforced plastics, and don't borrow them for non-lathe use. Metric and US [https://littlemachineshop.com/reference/numberdrillsize.php numbered]/[https://littlemachineshop.com/reference/letterdrillsize.php lettered] general use HSS drill bits are kept in two red metal index boxes next to the drill press.<br />
<br />
== Using the Lathe ==<br />
=== General ===<br />
A cutting speed chart for HSS tooling, published by Model Engineer magazine can be found [https://www.model-engineer.co.uk/sites/7/documents/cutting%20speed%20chart.pdf [here<nowiki>]</nowiki>]. The second row is the target feed rate and the rest of the chart, apart from the diameter column is RPM.<br />
<br />
For carbide tooling cutting iron and steels, recommended speeds are generally three times higher than for HSS, but the CJ18A 2500 RPM max. spindle speed (in high gear) means you can only reach the optimum speed range for over 15 mm dia work. For small diameter work, HSS tooling may well be a better choice.<br />
<br />
An online metric speeds calculator is here: https://www.cgtk.co.uk/metalwork/calculators/cuttingspeeds <br />
<br />
How to do the maths to calculate speeds and feeds: https://www.cutwel.co.uk/blog/speeds-feeds-made-easy<br />
<br />
Making dimensioned parts is primarily done by touching off the tool tip on a reference surface (with the lathe stopped, turning the chuck by hand), zeroing the handwheel dial, then manually counting turns and divisions. When backing off the tool its best to do so by exactly one whole turn so you don't forget the previous dial position. Stopping and measuring the work before taking the final cuts is essential if high accuracy is required. ''I've changed out the dial setscrews for flat tip ones with a tiny slug of solder under them so the dials are now friction fit on their shafts. i.e. if you hold the handle firmly taking up the backlash in the direction of cut, you can zero the dial just by grabbing and twisting it.''<br />
<br />
Carriage movement is less easy to measure as the handwheel is uncalibrated and advances an awkward bit over 19.2 mm per turn. Your options here when shoulders or other features must be exactly positioned are, in order of increasing accuracy: <br />
* Use measuring instruments, scribe the work at the desired length then work to the scribed line. Its often convenient to black the work with a permanent marker, then scribe with the tool tip, turning the chuck by hand.<br />
* for short distances, lock the carriage and use the compound, set parallel to the work<br />
* Set up a long travel dial indicator to measure carriage motion. <br />
N.B. with the leadscrew stopped, and the threading dial engaged, with its default 16 tooth gear, it will make one turn for every 24 mm of carriage movement (2 mm/div). This isn't accurate enough for positioning but is sufficient to check you aren't out by a whole mm or more.<br />
<br />
Do not allow any solvents to contact the chuck guard clear plastic as it will make the plastic brittle, or even craze it, and try to avoid melting it with the work light!<br />
<br />
=== Slide Locks ===<br />
* The carriage can be locked to the ways using the M5 hex screw through the top of the saddle to the left of the cross-slide. Double check the leadscrew is disengaged and the half-nuts open before locking it. Lock it when facing.<br />
* The cross slide can be locked by a M4 socket headed cap screw just in front of its middle gib screw. Locking the cross slide is helpful when turning very shallow conical features where the cross slide handle is in the way of the compound.<br />
* The compound slide can be locked by a M4 socket headed cap screw in line with the edge of the toolpost mount on the side with the gib adjustment screws. In normal use it should be kept backed off half a turn but it is desirable to tighten it for parting off operations to keep the resulting end faces flat.<br />
<br />
=== Chucks and Chuck Jaws ===<br />
==== Terminology ====<br />
* Inside jaws have steps on the outside to grip the ID of hollow work, but can also be used as outside jaws on small diameter parts (i.e. that fit through the spindle). <br />
* Outside jaws have steps on the inside to grip the OD of the work.<br />
* Universal chucks have a scroll plate with a spiral screw thread that moves all the jaws.<br />
* Independent chucks have individual adjusting screws for each jaw.<br />
<br />
==== The Chucks ====<br />
* The three jaw universal chuck can only grip near round or hexagonal work, which it centers, but its concentricity is not perfect so e.g. if you reverse the work and continue turning at the same diameter from the other end, you will see a line where the turned surfaces meet. It has separate sets of inside and outside jaws, and we normally keep the inside set installed to use as outside jaws for small diameter work.<br />
<br />
** Our jaws are individually numbered, stamped in the groove. They must be fitted in the correct sequence. The jaw slots are not clearly marked. Lowest runout for small dia. parts is achieved if you fit the jaws with #1 anticlockwise of the makers mark, then continue anticlockwise for #2 and #3.<br />
** A large strong rubber band is a great help getting all the jaws started on the scroll together - with slots #1 and #3 above the centerline and the scroll thread outer tip between #1 and #3, insert jaws #1 and #2 and put the rubber band round them to keep them in their slots. Insert jaw #3 and stretch the rubber band over it to hold it up into its slot. If the scroll was positioned correctly, all jaws should be at the same initial radius. The jaws can now be cranked in with the chuck key and they should all engage in step so they meet in the middle.<br />
:: ''Mini-lathe.com have the best instructions for [https://www.mini-lathe.com/mini_lathe/chucks/chucks.htm#Installing_Chuck_Jaws changing the jaws].'' <br />
<br />
* The four independent jaw chuck can grip most roundish or squarish work, which can either be carefully centered by the user, or deliberately gripped off-center. <br />
** Its jaws are reversible so can be swapped from inside to outside by simply cranking each jaw out and reinserting it the other way round, one at a time. DON'T move the jaws to different slots as they are likely to bind.<br />
** When setting up to face the sides of rectangular objects held crossways, it may be helpful to use both inside and outside jaw orientations, in symmetrical opposing pairs.<br />
** Its screws move their jaw 1/8" (3.125 mm) per turn<br />
<br />
* The jaws must '''never''' protrude from the chuck OD by more than one step, and for safety, its preferable they don't protrude at all, as they make the gap between the front of the bed and the chuck body an even more unforgiving meat grinder, and as the number of teeth engaged with the scroll or screw decreases, they loose strength, just when you need it the most to grip larger/heavier work. <br />
<br />
''Neither chuck is well suited to gripping tapered work safely. When seating work that doesn't quite fit through the chuck bore (which is larger than the 20mm spindle bore limit), be careful that it isn't seating on the chamfered edge of the chuck bore as it is far to easy to get the work slightly cocked so it doesn't run true.''<br />
<br />
==== Changing Chucks ====<br />
* When changing chucks, use the small grey plastic mat to protect the ways under the jaws in case you drop the chuck.<br />
* The spindle nose has two patterns of holes - the three hole pattern is for the three jaw chuck and the faceplate, and the four hole pattern is for the four jaw chuck. One hole is shared between the patterns, and is marked on the spindle nose.<br />
* To fit a chuck:<br />
** First check that the spindle nose and chuck back and recess are free of swarf, grit or other debris. Any foreign objects will tilt the chuck causing excessive runout and may mar the surfaces.<br />
** Remove the nuts and split lock washers from its studs, line its studs up with the hole pattern (preferably with the stud nearest anticlockwise to the makers mark through the marked spindle hole), fit and hold it in place with your right hand, and with your left, get the lock washer and nut on the top stud, and take up the slack.<br />
** One one nut is on, you no longer have to worry about dropping it, and can work round fitting the remaining washers and nuts, taking up the slack on each as you fit it. <br />
** Next, work round again getting them all finger tight, then tighten them gently, and finally work round fully tightening them. <br />
* Removal is the reverse of refitting. Put the washers and nuts back on the chuck's studs so they don't get lost.<br />
<br />
=== Faceplate Work ===<br />
Faceplate work is probably the most dangerous operation you can (or rather should) perform on a lathe. The working area is a large diameter spinning surface with protruding clamps to fixture the part that it is impractical to guard. Protruding clamps, studs, nuts etc. are very difficult to see at speed.<br />
<br />
'''Treat the faceplate with great respect and caution if you wish to continue to be able to count to ten on your fingers!''' <br />
<br />
The 65 mm cross-slide travel vs the 80 mm faceplate radius is a serious limitation that may require creative compound, toolpost and tool setups for larger parts, and doing full face cuts in two sections.<br />
<br />
''It is common practice to skim the faceplate to ensure it runs true. We have not (yet) done this, and wont till the spindle is in better bearings and the nose reground to minimise runout.''<br />
<br />
==== Clamping ====<br />
Open ended/sided clamps should be oriented so that cutting forces drive the work towards the clamping bolt/stud, not out from under the clamp. Minimize the protruding length of thread past the clamping nut, if necessary using sacrificial bolts or studs you can cut to length, or even using a long M8 stud for one of the faceplate mountings, so you can get a clamp nearer to the faceplate center. Double-check all clamps are secure, manually turn the faceplate to check the work and clamps clear the ways, top-slide and toolpost, and stand out of the 'line of fire' (a disc extending from the faceplate) when spinning up the work for the first time. <br />
<br />
If you need to machine close to a clamp, consider marking a safe limit circle on the faceplate and work with a marker pen to make it easier to see how close the cutting tool is to crash disaster. <br />
<br />
I strongly advise reading chapter two of Tubal Cain's book "Workholding in the Lathe" several times before your first faceplate setup, and if possible get another experienced lathe user to check your first few setups before spinning them up.<br />
<br />
==== Chuck Guard Removal ====<br />
The faceplate is too large diameter to fit under the chuck guard, but the guard has an interlock switch wqhich must be closed for the lathe to run. The guard is now fitted with wing nuts so it can be removed allowing the the interlock switch to close when using the faceplate. It *SHOULD* *ALWAYS* be refitted if a chuck is fitted, except when turning work too large to clear the guard. <br />
<br />
''The chuck guard is primarily there to make it very difficult to start the lathe without removing the chuck key and to reduce the area of large diameter spinning surface exposed. It may slow down the projectile if a chuck sheds a jaw but is unlikely to stop it. Also it serves to contain coolant spray spun off the chuck. As we don't use flood coolant this usually isn't an issue for us. As setting up for faceplate work doesn't use a chuck key, and the most hazardous zone is the face of the faceplate, with its spinning projecting clamps, with full access required for machining operations, which a guard would not cover, the consensus is that removing the guard is an acceptable risk.''<br />
<br />
=== Turning and Facing ===<br />
We are getting good results in aluminium, brass, and even steel using HSS cutting tools in quick-change tool holders, and the ~ 94 um/turn power feed. Unfortunately due to lack of rigidity in both the machine and smaller diameter parts, if you don't want the outer end to be over diameter, a light final cut and multiple 'spring' passes will probably be required.<br />
<br />
For aluminium, a sharp HSS tool and 0.5 mm (20 div) depth of cut gives good results with power feed for rapid stock removal. Its also easy maths as each cut takes ~ 1 mm off the diameter. Finish cuts should be much finer, 0.1 mm (4 div) is 'in the ballpark'.<br />
<br />
For steel, using carbide insert tooling, a 0.25 mm (10 div) depth of cut is more appropriate, and with pre-applied cutting oil, gives reasonable results with power feed if you use enough speed. The maths is not quite so easy as you are only taking 0.5 mm off the diameter per pass. Again, use finer finish cuts but try to plan your cuts so the final cut is still cutting, not smearing the surface!<br />
<br />
When facing or parting off, some skill is required to turn the cross-slide handwheel steadily to get a decent finish and to avoid shock-loading the tool tip. Increasing the spindle speed in one or more steps to keep up with the reducing diameter is advisable, but avoid speeds that cause resonances (resulting in chatter). When parting off, small through-hole parts may be caught on a thin rod chucked in the tailstock, and pre-positioned inside the work with its tip right up to the parting off position.<br />
<br />
==== Using the Steady Rests ====<br />
For the fixed steady rest, see Blondihacks' Lathe Skills #26 - How To Use a Steady Rest! [[#Youtube_Playlists_&_Videos|{below}]]<br />
<br />
Ours doesn't have ball bearing fingers, so a smooth surface on the work and adequate lubrication are essential. The thumbscrews can only tighten the fingers, so for small adjustments outwards you need to either slack off the clamping nuts or ease them slightly and use a drift against the back of the finger's slot. Once set, check the chuck still turns freely.<br />
<br />
The traveling steady rest needs to run on a machined surface, so at least for the first pass, must follow the tool, so its difficult to avoid using more compound slide overhang than is desirable. An initial surface should be cut next to the chuck or tailstock center before fitting the steady rest.<br />
<br />
Both are a PITA to fit - the fixed one has to have its clamping post inserted up through the bed, and the supplied spanner is useless near the headstock, and the travelling one's mounting holes on the saddle almost invariably need swarf picked out of them.<br />
<br />
==== Turning Between Centers ====<br />
<s>Using a MT3 to MT2 reducing sleeve, the MT2 dead center can be fitted in the spindle.</s> ''Currently the MT3 spindle taper is compromised.'' Alternatively, a soft center can be turned immediately before use in the three jaw chuck, but that must have its 60° point re-cut to concentric if the chuck is disturbed, and needs to be either large enough to bear on the chuck body, or must have a lip to bear on the end face of the jaws to take the axial thrust. Recutting the center is a PITA, as the compound angle must be set to 30° anticlockwise, then reset to a true 0° afterwards. Maybe a right-hand 30° end angle zero rake form tool is the answer, or use the carbide insert tool SSKCR0610H06 as a form tool with the toolpost rotated 15° anticlockwise.<br />
<br />
With the MT2 live center in the tailstock quill, this gives us a center either end of the work to hold it.<br />
<br />
We also need a drive dog similar to [https://littlemachineshop.com/products/product_view.php?ProductID=4473&category=1 this], and the corresponding drive post to bolt to the spindle nose. I have some 25mm bore thick wall iron pipe, which should do nicely. Lengths of the dog's straight tail and of the post TBD after I check how much the center protrudes. N.B. its recommended to tie the tail to the post to keep them in contact so they don't slam. ''Currently we will need to drive from the chuck jaws. Possibly use the exterior jaws with a short soft center gripped on the inside end and drive from the highest step.''<br />
<br />
=== Drilling ===<br />
Always start with a center drill so deflection of longer bits doesn't start the hole off-center. For larger bits (> 5 mm), first drill to the web size, then to final diameter. For a precision hole, drill slightly undersize and ream to final diameter. ''Supply your own reamers!''<br />
<br />
Caution: See note about the quill anti-rotation pin in section [[#Tailstock Quill|Tailstock Quill]] above.<br />
<br />
=== Boring ===<br />
Caution: As the spindle doesn't extend right through the headstock housing, if boring in a through hole, chips tend to fall out the back and tumble in the spindle bore till they fall into the change gears. To avoid this, one should plug the spindle bore with a wad of paper towel or rag and when cleaning up afterwards, use a rod to push it through towards the tailstock, with the chuck jaws (if fitted) wound clear of the spindle bore.<br />
<br />
A swivel bladed hole deburring tool (pale blue handle) can be found in the main room on the windowsill behind the drill press.<br />
<br />
A couple of boring jobs have been bodged with an awkwardly angled turning tool and achieving acceptable effective rake with enough clearance to reach deep enough into the hole has been problematic. I reviewed the tools we had and found none suitable for starting out in a 13mm bore, the max diameter we can (easily) drill. I therefore decided to buy a set of boring bars and make a holder for them. I had difficulty finding anything affordable under 10mm shank - the best low cost option was a [https://www.amazon.co.uk/dp/B07P5LGVBX set of nine 3/8" (9.525 mm) shank brazed carbide tipped boring bars], which would be close to the max capacity of the quick change boring bar holder - if we had one! Unfortunately this holder for our specific toolpost is difficult to find except in a toolpost bundle. Another annoyance is the variable tip height of the set, varying from 1.8 mm to 2.8 mm above the center of the shank.<br />
<br />
I therefore decided to make a boring bar holder of the [https://littlemachineshop.com/products/product_view.php?ProductID=1700 Littlemachineshop.com (USA) style] for use in the four way toolpost, as the additional rigidity will certainly help. Starting with a slightly over 50 mm length of 16 mm aluminium square bar and using the four jaw chuck , both ends were faced and an attempt was made to find its center and center drill it. It was then drilled out to ~9.8 mm after much drama due to blunt drills and drills that cut ~1mm oversize. Too big, but beggars cant be choosers as we didn't have a boring bar holder or a 3/8" reamer. Unfortunately the final hole ended up significantly off center. It was then chucked crossways and ~1 mm skimmed off its thickest side to gain clearance to allow it to be shimmed to height, then one side was slit lengthwise manually with a hacksaw.<br />
<br />
It was fitted to the for way toolpost and loaded with a booring bar, which clamped firmly. A 0.86 mm shim stack brought the tip of the largest boring bar almost spot on center height, with the difference easily accommodated by twisting the tool slightly. The three jaw chuck was then remounted, and a piece of iron pipe chucked for a test. It cuts well and leaves a decent surface finish.<br />
<br />
''The boring bar setup is a work in progress - talk to me before attempting to use them if you have a project that would benefit from boring..''<br />
<br />
ToDo: get something that can sharpen tools tipped with this grade of carbide - it needs some sort of diamond (or possibly CBN) wheel as green grit silicon carbide does little more than polish it. ''N.B. diamond wheels are rapidly eroded by grinding steel, so the supporting steel seat must be undercut with a regular grinding wheel before the diamond wheel can contact it.'' <br />
<br />
We'll also need 50 mm square sheet shims to fit under the toolpost to gain clearance in the toolpost above the tool or toolholder. A 2.4 mm shim would give us about the same above and below spindle center height, and we probably need a small selection of thinner ones.<br />
<br />
=== Thread Cutting ===<br />
The objective is to cut a thread that complies with the ISO metric thread profile. Our lathe is not currently equipped to cut non-metric threads, (with the exception of BA which have pitches based on metric threads of that era).<br />
<br />
[[File:ISO and UTS Thread Dimensions.svg|frame|center|Metric Thread Profile - from the geometry, H is ~86.6% of P]]<br />
<br />
Metric thread data - See 'Preferred Sizes' at: https://en.wikipedia.org/wiki/ISO_metric_screw_thread<br />
<br />
See "Mini Lathe User’s Guide" section '''Threading''' for general techniques *ONLY*, and above for change gears and threading dial setup.<br />
<br />
Amadeal specify the max. thread pitch as 2.5 mm. Any thread pitch greater than 1.5 nn requires the change gears to gear up. When gearing up it is desirable to distribute the ratio as evenly as possible over the two pairs of gears in the geartrain to avoid excessive tooth loading.<br />
<br />
==== External Threading ====<br />
Initially turn work to required Major Diameter, set up change gears and threading tool, touch off on the work, zero the top and cross slide dials, and do a 'scratch' pass to check the pitch. Back off the tool, return the carriage, and re-engage the half nuts on a valid dial line clear of the end of the thread then immediately stop the lathe, and hand turn the chuck till the tool tip is (hopefully) over the scratch to check the thread pickup. If all is good, return the carriage again, restart the lathe and start cutting your thread. <br />
<br />
Methods of doing so vary depending on the size of the thread and toughness of the metal, but straight-in plunge cutting is generally to be avoided as has the highest cutting forces, and does not reliably keep the carriage (and top-slide if set parallel to the work) loaded to avoid pitch errors due to backlash. <br />
<br />
If leaving the half-nuts engaged and reversing the lathe to return to the start of the thread for the next pass, its absolutely essential to back the tool out of the thread for the return pass as it will not follow the path of the cutting pass due to backlash in the geartrain, leadscrew mounts and half-nuts.<br />
<br />
==== Internal Threading ====<br />
''<nothing here yet>''<br />
<br />
== Cutting fluids ==<br />
=== Why bother? ===<br />
[https://youtu.be/mRuSYQ5Npek Watch this video] and contemplate what's actually happening to that thin ribbon of metal being removed. Most of the lathe's motor power is being turned into heat by internal friction in the chip being removed in the zone around the cutting edge, and surface friction at, and immediately behind the cutting edge, near-instantly heating the chip by up to several hundred degrees. Reducing the surface friction using a suitable cutting oil reduces the strain on the machine as a whole, and reduces workpiece and tool heating (and thus expansion) with consequent improvements in maximum usable feed and depth of cut, surface finish and accuracy. It also drastically increases the life of the cutting edge.<br />
<br />
=== Practicalities === <br />
We don't have a coolant system for the lathe and *really* don't want the maintenance hassles of using soluble cutting oil/coolant as if used infrequently its a PITA to keep recirculated high water content cutting fluids from going rancid and stinky, and they can also rust the ways, so even a total loss gravity feed system is problematic. Therefore if dry machining doesn't give a good enough finish, we tend to use oil applied topically, by hand to the work. <br />
<br />
* Hard brass is typically free-turning without oil, however some light oil for the final cut can improve surface finish, but with the disadvantage that it will increase loose chip buildup on the tool as hard brass typically forms short spalls or splinters rather than curly chips.<br />
<br />
* Many Aluminium alloys tend to be gummy, and Paraffin or other mineral spirits mixed with a little oil can help prevent the aluminum welding to the tool edge. WD40 will do at a pinch, but its messy to apply from a spray can.<br />
<br />
* Steel really needs *GOOD* cutting oil. Lard oil is the traditional choice for steel. If there are any objections to lard oil, we should bite the bullet and get some commercial dark high Sulphur cutting oil, but beware, many such oils use an additive package that includes lard oil.<br />
* Cast iron (except ductile) should be cut dry, as the carbon micro-inclusions self-lubricate it, and the carbide in the dust (primarily Cementite) are very abrasive, so tend to form a grinding compound if mixed with oil. <br />
<br />
I've sorted out an oil pot lid with a 1/2" brass collar soldered in to give a nice smooth sided hole, for ease of use and to minimize the risk of spills when using a brush to apply cutting oils, and got some dirt-cheap brushes. It fits Shippam's paste (and similar own-brand spread) jars and I've found several jars and ordinary lids to seal them for storage. Unfortunately it isn't the easiest to get this type of jars' lids back on square so they seal properly, and if you over-tighten them and there's a temperature change, they can be a total <expletive> to reopen. Using the rubberised handles of a large pair of pliers to grip the jar lid just above its rim is the best option, and avoids damaging the lids.<br />
<br />
''N.B. For the smaller brushes, the glue holding the bristles in is attacked by paraffin. To prevent loss of bristles, crimp the aluminium ferrule of each new brush of this type before use.''<br />
<br />
We have, in labelled jars:<br />
<br />
* Sulphurised Lard oil thinned with paraffin. Best choice for heavy cuts and threading in steel but stinky.<br />
* Lard oil thinned with paraffin. Good for steel and acceptable for softer copper alloys<br />
* Paraffin with a trace of light oil. Good for aluminium, and can help prevent squealing chatter on finish cuts in brass.<br />
<br />
I've also got some paraffin wax (in the form of a stubby candle), which can be applied lightly (under power) to brass and aluminium stock especially on the finish pass. It makes less mess than oil but unfortunately tends to build up on the tool tip, making it difficult to 'work by eye' without frequent pauses to clean the tool tip.<br />
<br />
We've also got a tin of [https://www.rocol.com/products/rtd-compound Rocol RTD cutting compound], which is a thick paste. Its highly recommended for drilling and tapping steel (in the drill press or by hand), but as a paste, is less useful for general lathe work unless thinned to a fluid consistency, e.g. with paraffin or white spirits. OTOH its certainly worth trying for high speed facing steel as it is less likely to get flung off.<br />
<br />
== Cleaning and Maintenance ==<br />
Swarf is a significant cut hazard to the operator, especially stringy swarf from cutting steel. Never touch it bare-handed - always use a tool e.g. a brush, or a hook, or needle nose pliers for grabbing long swarf.<br />
<br />
* After use, brush all swarf off the toolholder, compound and cross slide etc. ways and leadscrew. Ian B has blocked off the opening at the headstock end of the rear splashguard (to try to keep swarf out of the motor), so one must sweep the swarf towards the open tailstock end and catch it in a dustpan or similar. Preferably, also thoroughly clean out the chip tray under the lathe, but at least sweep out visible swarf.<br />
* Wipe up any cutting fluid residue and re-lubricate affected sliding surfaces with way oil.<br />
* Do not solvent clean the chuck guard, as it will make the plastic brittle, or even craze it. Water with a little detergent is permissible for cleaning it, with the guard totally removed from the lathe.<br />
<br />
Before engaging the half-nuts for power feed/threading, check the leadscrew is clean! ''Best cleaned under power, with a toothbrush.'' <br />
<br />
'''Caution:''' The traverse gears behind the carriage handwheel are in an open-backed housing and tend to become packed with swarf! Swarf buildup here will result in jerky carriage movement. Clean out as much as you can with a toothbrush ...<br />
<br />
===Lack of lubrication and/or swarf or dirt build-up can be disastrous===<br />
* If using the change gears/power feed, lack of lubrication of the B-C stub shaft center pin or either leadscrew end bearing can result in seizure and immediate destruction of one or more gears in the gear train or worse. <br />
* Small pieces of swarf can get between the saddle and ways, or into the slides degrading accuracy, possibly permanently if hard swarf scores them, or jamming them. The carriage handwheel gears behind the apron are notorious for accumulating swarf, and swarf buildup on the leadscrew can prevent the half-nuts engaging properly, resulting in scrapped work, and possibly stripped half-nuts. <br />
* Metal swarf can get into the motor (''though Ian B has modified the rear chip catcher to reduce the risk)'' or into the control box via the leadscrew, and short-circuit stuff. At best it will blow the fuse and need a strip-down to clean it out, at worst it may require a replacement [https://www.amadeal.co.uk/acatalog/Speed-Control-Circuit-Board--12amp-AMA_SP_CJ18_SCB12.html#SID=12 speed controller] ''(currently £96)'' and/or [https://www.amadeal.co.uk/acatalog/550W-motor-for-CJ18A-Mini-Lathe-467.html#SID=240 motor] ''(currently £105)'' and possibly other electrical parts. We should probably fit a [https://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C3-Mini-Lathe-Spares/C3-256-Leadscrew-Grommet-Dustproof-Cover C3-256 Leadscrew Grommet] to keep swarf out of the control box, as it tends to drop onto the 'Filter' board which is mounted horizontally, below the leadscrew.<br />
* Grit from grinding, sanding etc. forms a grinding paste with the way oil, and will rapidly wear out the ways, saddle and slides. Keep grit off at all costs e.g. by covering the ways and slides during grinding/sanding operations, and if there's any chance grit has gotten where it shouldn't, clean and re-lubricate *BEFORE* moving the carriage or slides, then move the carriage and slides, wipe down where they were with a clean paper towel and check there's no remaining traces of dirt other than clean way oil on the paper towel. If it doesn't come clean when you re-lubricate and move it again, a full strip down may be required to solvent clean and relubricate the precision sliding surfaces.<br />
* Although a metalworking lathe *can* be used to turn hardwood, wood dust and small chips are extremely pernicious, as they get everywhere, even clinging to clean surfaces, are abrasive due to their silica content, and are hygroscopic, promoting rust. An even more thorough clean-up than after using abrasives is needed, immediately afterwards. Oily wood dust and fine wood chips in significant quantities are a fire hazard, even in the trash bin.<br />
<br />
===Lubrication===<br />
See section: "Lubrication" in LittleMachineShop.com "Mini Lathe User’s Guide" [[Ian_M's_Lathe_Notes#Manuals|(below)]]. As we usually only open two nights a week, in the table on page 16, Daily lubrication becomes Weekly and Weekly becomes Monthly.<br />
<br />
===General Maintenance===<br />
* The grubscrews holding the cross-slide and compound slide dials tend to loosen due to vibration and use of the dials. Keep them snugged up, but not so tight the dials cant be set without an Allen key.<br />
<br />
* The screws holding the cross-slide nut tend to work loose due to vibration. Crank the handle to and fro through the backlash and visually check there is no movement of the screw heads in their holes. If there is, see the [[#Excessive_cross-slide_backlash|notes below]].<br />
<br />
===Removing the Carriage===<br />
Its possible to remove the carriage from the bed for cleaning etc. without dismantling it. The only stop to its motion is the righthand leadscrew bearing.<br />
<br />
Start by removing the tailstock. Crank the carriage to the tailstock end then remove the leadscrew bearing (two screws and a nyloc nut on the leadscrew end). With the half-nuts open, hold the leadscrew centered in them and crank the carriage off the end of its rack, then slide it off the end of the bed.<br />
<br />
Refitting is the reverse of removal, except (if its gibs are correctly adjusted) the carriage will be very tight on the end of the bed ways so may be difficult to work onto the ways without a stack of blocks of wood or similar to support it at exactly the right height. The righthand leadscrew bearing must be refitted with the carriage as close as possible to it and the half-nuts firmly closed to support the leadscrew at the correct height to hold it in alignment while the screws are being tightened. The nyloc nut controls leadscrew end-play. Fully tighten it then back it off slightly till the leadscrew turns freely with its change gear removed.<br />
<br />
If the Apron has been off, refit it with the screws no more than lightly finger tight and only finally tighten them after checking lead screw engagement at both ends of the carriage travel and that the rack and pinion operates smoothly over the full travel.<br />
<br />
== Issues and Annoyances ==<br />
As of September 2023 - mostly resolved, apart from the spindle bearings and runout, the lathe is in better condition than it has been for a number of years.<br />
<br />
===Four Jaw Chuck has two jaws too tight===<br />
Fixed 27/10/2023: The grooves in the opposite sides of the jaws that run in the chuck slots were slightly out of true, and the rails either side of the slots were slightly too thick towards the center. Due to the difficulty of seeing the high spots, after cleaning up and deburring the jaws didn't do enough to ease them, I decided to grind the top of the rails where they were binding. Several repetitions of spotting, grinding then diamond filing the high spots has eased them enough. I cleaned everything, greased the jaw slides and screws, and refitted the studs so the chuck is now fit for service. <s>Two of the chuck jaws are tight in their slots, making precise adjustment difficult due to lack of 'feel'. Moving the jaws round the slots shows the problem follows the jaw not the slot, and stoning various edges hasn't helped so it seems that the affected jaws are slightly oversize. Need Engineer's spotting blue to determine which of the sliding surfaces is binding, so we can see what needs scraping/stoning/grinding to fix them</s><br />
<br />
''N.B. Don't move the jaws to a different slot - the formerly tight jaws *must* stay in the slots furthest from the makers mark.''<br />
<br />
===Excessive Runout===<br />
Mostly fixed 24/10/2022: I ground the chuck seating surface of the spindle nose (outside lip) to under half a thou runout. This also cleaned up several burrs. It would be possible to do better, but that would need good spindle bearings, and a more rigid toolpost grinder mount.<br />
<br />
Our spindle nose was damaged years ago by a person with little mechanical aptitude (who shall remain nameless) beating it up with a hammer mushrooming the spindle nose. We are getting several thousandths runout at the end of the MT3 bore, a MT3 to MT2 reducer sleeve in it runs visibly out of true, as does the spindle nose flange. When you put a chuck on it, the runout is magnified by the distance from the spindle nose. Ideally we would replace the spindle when we change the bearings but its £52 [https://www.amadeal.co.uk/acatalog/4-Spindle-Upgrade-Real-Bull-Mini-lathe-CJ18-series-AMA_SP_CJ18_003RB.html#SID=9 from Amadeal] and money is tight. It may well require more work after the bearing upgrade. Once good bearings are in, if we can borrow a decent MT3 arbour as a reference, we should consider skimming the bore.<br />
<br />
===Spindle bearings===<br />
* The spindle bearings appear to be close to worn out. They are notably noisy when running, and there appears to be more slop in the spindle than is desirable. We have some ideas for possible replacement/upgrade, but it requires a major teardown.<br />
<br />
: The original bearings are allegedly 6206-2RS or 6206-ZZ deep groove ball bearings - 2RS codes rubber seals both sides and ZZ codes metal shields. Although the deep groove gives reasonable ability to withstand axial loads, the bearing balls point contact means they are vulnerable to [https://en.wikipedia.org/wiki/Brinelling brinelling] due to shock loading. The jammed on three jaw chuck didn't help this, as before we skimmed the spindle nose lip, it had to be driven off using a bar through the spindle bore, shock loading the bearings every time. Also even a minor 'crash' could have brinelled them due to eccentric shock loading, and the lathe has previously been crashed badly enough to need drive gear replacement. There are also issues with the 'approved' method of spindle and bearing removal from the headstock brinelling them, even if you don't abuse the spindle nose with a hammer!<br />
<br />
: A possible replacement is 30206 tapered roller bearings. The new bearings are slightly thicker so the plastic spindle spacer (15) needs to be machined to length to get the 45 tooth spur gear that drives the change gears laterally aligned with the tumbler gears. If a temporary replacement (3D printed?) is fitted, the lathe can be run (without power feed capability) so this can be done on the lathe after fitting the new bearings. As tapered roller bearings have line contact, they are significantly more resistant to brinelling.<br />
<br />
: ''See [[Talk:Ian_M%27s_Lathe_Notes]] for notes, links etc. for this upgrade.''<br />
<br />
===Motor stuttering===<br />
* Fixed 21/09/2023: The motor was running very erratically and it was very difficult to set a speed. Several loose connections were found in the control box, mostly loose female spades to the motor controller board, but also a dry jointed braking resistor on the 'Filter' board, and an inhibit wire completely off its terminal on the forward/reverse switch, making intermittent contact. After tightening and/or remaking all affected connections, it was much improved but still not right below 300 RPM. The remaining issues were due to poor wiper contact in the speed control pot, and stripping it, cleaning the track and contact ring and re-tensioning the contacts resulted in the motor now running smoothly over the full speed range. The speed is slow to settle, and while part of that is probably the lag in the digital tach, I suspect that the KBIC motor speed controller isn't properly tuned as it was (allegedly) previously replaced.<br />
<br />
===Drive belt slipping===<br />
* Fixed 28/9/2022: During testing the motor after the above issue, it was noted that the chuck could be stalled, slipping the drive belt, with not much torque. The drive belt was determined to be loose and a bit worn, but still in acceptable condition. <br />
<br />
: Access for servicing the belt requires removing the control box ''(2 spades to ZVR switch disconnect the supply, speed sensor and motor simply unplug from the 'filter board')'', the motor cover, chuck guard switch assembly + wiring cover, the change gear 'A' (drive) shaft carrier assembly, and the tumbler gear assembly. See https://youtu.be/EkxlIz01BdA for disassembly/reassembly, though on our lathe, the speed encoder ring on the spindle prevents the belt cover from being fully removed without disturbing the spindle nuts. There is enough room to work with it loose, but still trapped by the encoder ring. Also, unlike the video, if the 'jack' screws under the headstock are correctly adjusted, and the studs aren't excessively bent, there is no need to make custom studs. <br />
<br />
: It turns out that our lathe was missing the M6 hex headed jack screws that press the motor down to resist the belt tension, and the motor had cocked out of position at a severe angle. I know Ian B had had considerable trouble adjusting it after the motor fault back in October 2022, and I believe it had been getting slowly worse ever since. The jack screws were probably mistaken for headstock fixing bolts during disassembly after the crash that resulted in the metal Hi/Lo gears being fitted, then lost. The penny washers on the studs had dished, so I turned them over and backed them up with smaller washers and switched to nyloc nuts so they cant back off due to vibration. N.B. there is a packing washer on the motor side on one of the studs, presumably so the shaft is true to the ways. Adjusting the motor is awkward to say the least. One has to slack the stud nuts off a lot, pry under its rear end to lift it enough to be parallel to the ways, snug the stud nuts, check alignment, then set the jack screws and their lock nuts to hold it there, and finally tighten the stud nuts. <br />
<br />
: Tension: According to Sieg, it should be possible to twist the belt 90° mid span with a light finger grip. Other sources say 1/32" - 3/32" deflection mid span with light finger pressure.<br />
<br />
===Speed display blanking===<br />
* The speed display has been intermittent, blanking and flashing 8888 and 0 at certain speeds for as long as I have been using the lathe. Finally on 18/07/2022 it failed completely, with no display. I removed the display module and bench tested it - the pins are labelled 5V GND PL PE, PE is frame ground and PL is a TTL level pulse from the speed sensor - confirming that it was in good working order. My suspicions then turned to its power supply on the 'Filter' board. With both the sensor and display unplugged, the 5V rail was found to have a only a couple of volts, but the unreg DC was 17V and stable. Replacing the 78L05 5V regulator restored the 5V rail and normal operation.<br />
<br />
: ''I conclude its been failing for a while with high load current due to speeds with more lit segments causing it to drop out, resetting the speed display, causing it to blank, lowering the current enough for the regulator to recover, then the display MCU lamp tests (8888) then re-acquires the speed, repeating ad-nauseum till the speed is changed. I don't like the design as the high input voltage results in excessive dissipation.'' <br />
<br />
: ''ToDo: Bench test display to measure its worst case current consumption, then fit an appropriate dropper resistor to reduce the 78L05 dissipation.''<br />
<br />
===Quill spinning when drilling===<br />
* The quill was tending to spin while drilling because its anti-rotation pin (a M5 dog tip setscrew) was sheered. I've removed the debris, aligned the scale with the top of the tailstock and fitted a longer M5 dog-tip setscrew to replace it, with a nut to lock it at the correct height. N.B. the pin isn't that 'meaty' so if using big drills in tough metals, to prevent shearing it, it should be backed out so the quill can be turned by hand and unwanted rotation controlled by being quick with the quill lock if it starts to spin, or even using a close fitting rod in one of the chuck key holes with plastic tube over it to protect the ways. <br />
: ''If the screw sheers again, the quill will need to be removed and the tailstock taken off the lathe so the sheered tip can be shaken out, and if the setscrew is difficult to remove it probably means the threads are mangled where it sheered. Try driving it right through with the quill out.''<br />
<br />
===Sloppy quick change toolpost locking mechanism===<br />
* Once the dovetail clamp screw was slackened, there was nothing preventing the dovetail twisting or cocking significantly, and friction with the toolholder made it tend to do so, making toolholder insertion and removal more difficult unless the clamping screw was backed off excessively. I added a compression spring around the clamp screw inside the toolpost to push the dovetail outwards so it mostly retains alignment when open, allowing toolholders to slide on or off cleanly with far less screw slackening.<br />
<br />
===Leadscrew rubbing===<br />
* The leadscrew shaft is rubbing on the insulating separator inside the control box. Unfortunately the corner of the relay on the Filter Control Board (#160) doesn't allow enough clearance. Although the friction isn't much of a problem at high reduction ratios, e.g. 16:1 power feed, it increases the stress on the change gear train, and may be problematic when threading at feeds above 1:1. ''Possibly pack out the control box mountings by a couple of mm.'' <br />
<br />
===High/Low lever backwards!===<br />
* The high-low drive gear selector behind the headstock is incorrectly labelled and differs from the manual: low gear (which we normally use) is with the lever towards the tailstock. ''I suspect that the gears in the headstock were refitted the wrong way round when it was upgraded to metal gears.''<br />
<br />
: ''ToDo: Get it reassembled the right way round during the spindle bearing upgrade!''<br />
<br />
===Carriage lock fouls top slide===<br />
* The T handscrew has been replaced with a M5 hex headed bolt, to permit access when the top slide is over it. An 1/4" drive 8mm socket is usually left on it, but needs to be removed when the full cross slide travel is needed. The small (4 jaw) chuck key is near enough 1/4" to use for it. If you need to (un)lock it while the compound is over it, you'll need an 8mm spanner. ''The [https://www.amadeal.co.uk/acatalog/Mini-Lathe-Carriage-Lock-463.html Amadeal lock screw] is in the spares tin as it was too high and fouled the compound slide.''<br />
<br />
===Tailstock locking lever loose===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock - See full image for key to screws]]<br />
* Diagnosed and fixed 10/1/2023 - In the base of the upper section of the tailstock, there are two dog tip set screws that engage with locating grooves in the counter-rotating shafts carrying the eccentric locking cams. They'd backed off, probably due to vibration. They need to be tightened till they bottom out in the groove, making sure they are '''in''' the groove, backed off half a turn so the shafts can turn easily, and locked in place. There's no facility to do so, so reassemble with weak threadlocker. Unfortunately to get to them you have to remove the tailstock base slide, which is held on by the pressure of four adjusting grub screws, which all need backing off, and one socket headed bolt from underneath so full tailstock realignment is required after reassembly, which even for a rough alignment is tedious.<br />
: <s>The tailstock locking lever is loose and can be pulled out on its axis. It works OK when fully pushed home but needs investigating. ''I tightened the grub screw as the lever was coming off its shaft, but the whole shaft pushes/pulls in and out. It works OK fully pushed in, but it seems something that is meant to retain it has failed inside the tailstock base.</s><br />
<br />
===Gear alignment issues===<br />
* Change gear alignment is poor. I've currently got a gapped washer (to clear the key) packing out the A shaft so the gears line up, but this reduces the key's engagement so is problematic due to the high loading if the gears are set up for coarser threads. <s>Also I need to turn down some penny washers to slightly less than the root diameter of the metal 20T pinions, as gear retaining washers.</s> ''The gear retaining washers for A gear and B-C stub shaft are now done, turned down to slightly under 16 mm dia. Spares in the change gear tin. ToDo: The D (leadscrew) washer requires a larger center hole, so make two more with that hole.'' <br />
<br />
===Saddle gibs loose===<br />
* Fixed 11/04/2023: I took the apron off for access (and to clean the carriage handwheel gears), and found the front sheer plate screws were completely loose. I've snugged them up some and set the opposing grub screws and got a lot of the slop out. I've re-checked the front ones, and taken up the slop in the rear ones - Unfortunately it wasn't possible to get carriage movement to have an even 'feel' over its whole travel, and its noticeably tighter near the tailstock. If light hand pressure on the side of the unlocked carriage can cause movement (with the half-nuts open), its time to readjust them again, though it should be possible to move the carriage with a firm push. <s>The saddle gibs (actually the sheer plates) were too loose, to the point that engaging a slightly stiff threading dial could cause it to self-feed, an obvious crash hazard if working near the chuck or a step in the work.</s><br />
<br />
''N.B. the lefthand front opposing grubscrew is short, (fully recessed) and unlike the others does *NOT* have a locking nut as it must clear the traverse pinion. A wrap of PTFE tape provides enough friction to keep it in place, though possibly a bit of nylon fishing line down its hole would be better.''<br />
<br />
===Excessive cross-slide backlash===<br />
* ''Fixed 21/11/2023. Originally, back in October 2023, The cross-slide screw had excessive backlash (nearly three turns), which increases the risk of loosing track of the cut depth when cutting steps, and during threading operations. If you ended up off by a turn too far in, a crash would be the most likely outcome.<br />
: The original excessive backlash was traced to loose cross-slide screw nut mountings. The nut has two socket headed cap screws pulling up, one either end, accessible from the top of the cross-slide, which control the tilt of the nut to take up backlash in the nut, and an opposing grub screw pressing down on the center of the nut to make it longitudinally rigid. Snugging up the grub screw reduced the backlash to 10 divisions or so, or 0.25 mm. A year later, the backlash had increased to one turn due to the cross-slide nut mounting screws working loose again.<br />
<br />
: 07/11/2023: I investigated further: It is difficult to get the cross-slide nut aligned correctly as it must be at the same height as the screw which is constrained by the bearing surfaces in the bracket. With the cross-slide almost at the front limit of its travel, I removed the screw and set the nut as level as possible and visually centered in the bore, then re-fitted the bracket and screw, then adjusted the tilt till it turned freely through the backlash. I then tilted it up at the front till some drag was felt to minimise the backlash and tightened the screws to lock it in place balancing them to maintain the same feel as I tightened them. The result was 7 divisions of backlash, acceptable but not great. During normal turning operations, the load on the nut is tension on the front screw and pressure on the grubscrew, so if it slackens again due to vibration from chatter, odds are it will be the rear screw that's loosened.<br />
<br />
: 16/11/2023 - 21/11/2023: The backlash had crept back up to 11 divisions (0.275 mm). We don't have any >14 mm brass stock (or even near that) so I tried making the shim washer out of aluminium. I was shooting for 0.24 mm but due to poor technique got 0.28 mm. No good - locked solid. I lapped it down and tried it till I got it down to 0.20 mm which gave about 3 divisions backlash - good enough, but the screw was too tight due to the shim washer not being bevelled at its outer edge resulting in it cupping in its seat. Filing a bevel round the OD and re-lapping it resulted in a 3 - 4 divisions of backlash. Its a little mushy due to the washer having been kinked removing it, so ideally a new (brass) washer should be made. <br />
<br />
* Further reduction of backlash: https://youtu.be/Wu_tI29JL2Y?t=163 <br />
: Brass tinned with Pb-free solder to form a white metal bearing surface should work at least as well as the bronze used in the video. The shim washer needs to be 10.2mm ID, with a full thickness bevel on a 14 mm OD. It isn't necessary to remove the lead screw from the cross slide, as the washer can be fitted in-situ with only the bracket removed.<br />
<br />
===3 Jaw chuck didn't mount properly===<br />
* Fixed 7/4/2023 by grinding the spindle nose lip. The three jaw chuck can now be installed and removed by hand with no hammering. A test bar in it now has only 2 thou runout (TIR) at the chuck.<br />
: <s>The three jaw chuck and the faceplate aren't seating properly on the spindle nose. Its too tight on the register diameter of the lip. This results in grossly excessive runout, and also makes this chuck and the faceplate a PITA to fit or remove.</s><br />
: ''The spindle nose had been abused with a hammer (before my time) which mushroomed it and may have brinelled its bearings. See '''Excessive Runout''' and '''Spindle bearings''' above.''<br />
<br />
== Manuals, Books and other resources ==<br />
=== Manuals ===<br />
The [https://wiki.richmondmakerlabs.uk/images/a/a3/Lathe_InductionNotes.pdf RML CJ18A Mini-Lathe Induction Notes]. Your mandatory Lathe Induction will cover most of this but its good to be able to refer back to it.<br />
<br />
Official [https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Amadeal CJ18A Manual], or paper copy (less complete) kept on shelf above lathe.<br />
<br />
The [https://www.chesterhobbystore.com/wp-content/uploads/2022/11/Conquest-Super-Lathe.pdf Conquest Super Lathe manual] is considerably better than the Amadeal manual and is for a near-identical machine.<br />
<br />
The [https://littlemachineshop.com/images/gallery/info/minilatheusersguide.pdf Mini Lathe User’s Guide] from LittleMachineShop.com is even more comprehensive, going into its usage in some detail, with a proper TOC, and covers both US and Metric versions of Realbull Mini-lathes. ''The only fly in the ointment is the threading section assumes a US lead screw so change gear selections and threading dial divisions will not be correct for our lathe.''<br />
<br />
[https://www.arceurotrade.co.uk/machineguides/C3-Mini-Lathe-Dismantling-and-Reassembly-Guide.pdf Sieg C3 Mini-lathe Dismantling and Reassembly Guide] "A picture story book to help you dismantle and reassemble your Sieg C3 Mini-Lathe" ''It is similar enough to ours to serve as a maintenance guide, except for the electronics, spindle drive and other headstock innards.<br />
<br />
The motor controller is a clone of a [https://acim.nidec.com/drives/kbelectronics/-/media/kbelectronics/documents/dc-drives/manuals/kbic_manual.ashx?la=en KBIC® SCR DC Motor Speed Control]<br />
<br />
=== Books ===<br />
'''Metal Turning on the Lathe''', by David A Clark, Crowood Metalworking Guides, ISBN-13: 978-1847975232 [https://www.amazon.co.uk/gp/product/B00E78RKIG Kindle Edition (£8.99)]. ''A 'free' epub can be googled for, *NOT* linked here due to dubious legality.''<br />
<br />
'''[https://archive.org/details/03screwcuttinginthelathe Screwcutting In The Lathe]''', by Martin Cleeve (a pen-name of Kenneth C Hart), Workshop Practice series #3, ISBN-13: 9780852428382<br />
<br />
'''[https://archive.org/details/15workholdinginthelathe Workholding in the Lathe]''', by 'Tubal Cain' (a pen-name of Tom Walsh), Workshop Practice series #15, Argus Books, ISBN-10: 0852429088<br />
<br />
'''[https://archive.org/details/20metalworkandmachininghintsandtips Metalwork and Machining Hints and Tips]''', by Ian Bradley, Workshop Practice series #20, ISBN-13: 9780852429471<br />
<br />
'''[https://archive.org/details/38toolandcuttersharpening Tool and Cutter Sharpening]''', by Harold Hall, Workshop Practice series #38, ISBN-13: 9781854862419<br />
<br />
'''[https://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpaperT204.pdf Cutting Fluids]''', by EC Bingham, NIST Tech. Paper No. 204, 1921<br />
<br />
=== WWW resources ===<br />
==== Mini-lathe Specific ====<br />
There's a *LOT* of mini-lathe info online. Notable sites include:<br />
* http://www.mini-lathe.com/ - A major Realbull/Sieg mini-lathe resource.<br />
* http://mikesworkshop.weebly.com/lathe-modifications.html - many mods including carriage DRO autostop, and variable speed leadscrew motor drive, cross-slide motor drive, etc. He also has a page with a bunch of accessories, toolholders etc. - http://mikesworkshop.weebly.com/lathe-accessories-and-tooling.html<br />
* http://andysmachines.weebly.com/variable-speed-controls.html - Scroll down to the 'UPDATE' section for the schematic of a very similar SCR speed control board. It also has the schematic for an earlier version of the Auxiliary Control Board (aka: 'Filter' board).<br />
<br />
==== Forums ====<br />
''with publicly accessible archives''<br />
* https://groups.io/g/7x12MiniLathe - Mini-lathe specific, active<br />
* https://www.hobby-machinist.com/forums/mini-lathe-mini-mill-information.220/ - active<br />
==== Youtube Playlists & Videos ====<br />
* Blondihacks: [https://www.youtube.com/playlist?list=PLY67-4BrEae9Ad91LPRIhcLJM9fO-HJyN Lathe Skills] (playlist) - "This is an educational series to help you learn to use your metal lathe. Watch them in order for best results! Satisfaction not guaranteed, especially if you're a cranky sort of person."<br />
* Frank Hoose (Minilathe.com) has a couple of relevant Youtube playlists:<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn7ON0jGM5UbM-KZDT56MOIp Mini Lathe Operations]<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn4nGRZaVq3wTOlvZNOmdAZ2 Mini Lathe Overview]<br />
<br />
==== General Machining ====<br />
* https://www.machiningdoctor.com/ - "THE #1 MACHINING TECHNICAL HUB"<br />
<br />
==Projects==<br />
[[File:VESA mount.jpg|thumb|Machined VESA mounting plate (left) and plate from Dell monitor stand it must match (right). The translucent washer shows the size of the original center hole.]]<br />
* My first faceplate project was boring out the center hole in a VESA mounting plate to adapt it to fit onto a surplus Dell 1708FP monitor stand. The part was centered using the tailstock dead center engaging with its original center hole. I clamped the part with studs and penny washers on the driving side of two opposite corners, with cap screws in the next slot round to trap the corners under the clamping washers, then withdrew the tailstock and dead center. After machining out the bore, I used the tip of the tool, rotating the chuck by hand, to scribe a circle for laying out the bolt holes. I finished off laying out and drilling the bolt and locating holes by hand at home, fitted it to the stand, and mounted the 2nd hand LG 24" widescreen monitor.<br />
<br />
* Another ultimately unsuccessful project was fly cutting aluminum flat bar to thickness to make custom shims for the set of carbide insert tools, for the four way toolpost. The 8 mm shank tools need ~2.5 mm shim stacks, and the 6 mm shank tools need ~4.5 mm shim stacks. Ideally I'd machine single shims, but the only stock I've got handy cleans up to only 3.2mm, and some fine shimming may be needed to fine-tune the tool height.<br />
<br />
: After sorting out the clamps so they were no longer twisting the aluminum flat bar stock, and switching to the short 45° turning SCMT06204 insert tool in the four way toolpost, to improve rigidity and get a well controlled tip radius, the finish was much improved. I'm still having problems getting an even thickness and am getting approx. 0.05mm variation, I suspect due to the aluminium bar stock distorting due to internal stresses as its surface is cut away. ''ToDo: try supergluing the stock to the faceplate before clamping to further reduce chatter and stop the warping.''<br />
: Looking back on this project a year later, its fairly obvious that the thickness variation was probably due to faceplate surface runout due to the damaged spindle nose.<br />
<br />
* Raphael has been working on a steel rocket nozzle with some assistance from myself. We have set up the rough cut chunk of ~ 50mm steel bar, faced both ends (to 50mm length) and turned the OD to 49mm to clean it up. Its going to need through drilling, probably some boring, and quite a bit of detail work on the OD. It will then need to be transferred to a jig in the drill press vice to allow a pattern of angled traverse holes to be drilled with acceptable accuracy.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_Lathe_Notes&diff=17588Ian M's Lathe Notes2023-11-17T07:33:10Z<p>IanM: /* Excessive cross-slide backlash */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br />
<br />
''Currently these notes are semi-organized and non-authoritative. As I become more experienced with the RML CJ18A mini-lathe, I'm cleaning up, extending and reorganising them. Some lathe operating experience is assumed. If in doubt, '''*ASK*''' me, Andy H<sup>*</sup> , Jonathan H or another experienced minilathe operator!<br />
<br />
''* Andy H should be asked (for an authoritative answer) any questions involving RML usage policies or acquiring tooling or materials through RML.''<br />
<br />
== The Lathe ==<br />
Our Facilities page [[Facilities#Lathe|has]]:<br />
<blockquote><br />
'''Lathe'''<br />
[[File: Lathe2.jpg |200px|right | Lathe]]<br />
In the kitchen. <br />
<br />
Marked as a CJ18A Mini-Lathe from [[https://www.amadeal.co.uk/acatalog/CJ18A-Mini-Lathe-7x14-Machine-100mm-3jaw-Metric-With-Metal-Gears-AMA_LA_CJ18_M_3_MGRB.html Amadeal]]<br />
[[https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Manual]] <br />
<br />
[[Media:Lathe InductionNotes.pdf| Induction Document]]<br />
<br />
Possible upgrades:<br />
*https://www.youtube.com/watch?v=GwT-JQLbNPA<br />
<br />
''Please do not use the lathe until you have received induction'' <br />
<br clear=all><br />
</blockquote><br />
Its a Chinese import 7x14 mini-lathe. The 7x14 refers to the maximum diameter and length of work, in inches and is only a theoretical measure of the working envelope as you loose length to the chuck + any tailstock tooling, and the diameter is over the bed, not the cross-slide. See actual specifications below. <br />
<br />
Most if not all Chinese 7x10 to 7x16 mini-lathes seem to be remarkably similar (not uncommon with Chinese products due to [https://www.bunniestudios.com/blog/?p=284 Shanzhai (山寨)] )<br />
and the OEM of our Amadeal CJ18A Mini-Lathe was probably [https://www.made-in-china.com/showroom/cheap-lathe Yangzhou Realbull Machinery Co. Ltd]. Very similar lathes are also made by [https://www.siegind.com/lathe-machine.html Sieg], but their lathes tend to be slightly less sophisticated than the equivalent Realbull models.<br />
<br />
''N.B. Many Sieg parts are known to have slight but critical differences from Realbull parts, so '''DON'T''' order Sieg spares for a Realbull lathe!<br />
<br />
== Key Specifications ==<br />
Amadeal says the CJ18A Mini-Lathe is a 7x14 model with:<br />
<blockquote><br />
* Power 550 W<br />
* Distance between centres : 350 mm<br />
* Swing Over Bed: 180 mm<br />
* Swing Over Cross Slide: 110 mm<br />
* Taper: MT3<br />
* Tailstock Taper: MT2<br />
* Chuck diameter: 100 mm<br />
* Spindle Speed: 50 - 2500 rpm ''(with digital readout)''<br />
* Spindle Bore: 20 mm<br />
* Cross slide Travel: 65 mm<br />
* Range of Metric Threads: 0.5 - 2.5mm.<br />
</blockquote><br />
* The lead screw is metric, pitch 1.5 mm.<br />
* The spindle center is 90.6 mm above the flat of the bed (measured).<br />
<br />
Even though the compound and cross slide handwheels appear to be calibrated in thousandths of an inch, as ours is a metric machine, they only approximate that. One turn of a slide handwheel is 1mm advance, and they have 40 divisions, so each division is 0.025 mm, (approx. 0.984 [https://en.wikipedia.org/wiki/Thousandth_of_an_inch thou]). Similarly, the tailstock quill advances 1.25 mm per handwheel turn, which has 50 division dial, giving the same 0.025 mm divisions, but only 4 turns per 5 mm. The carriage handwheel is awkward - it moves approx. 19.2 mm per turn, and doesn't have a dial scale.<br />
<br />
== Notable Accessories ==<br />
We have:<br />
* [https://www.amadeal.co.uk/acatalog/160mm-Face-Plate-for-the-4-Mini-lathe-AMA_AC_CJ18A_FP160RB.html#SID=129 160 mm (6 1/4") Faceplate]<br />
* 100 mm (4") three jaw self-centering chuck (OEM standard) 22.5mm bore, with inside and outside jaw sets<br />
* 100 mm (4") four jaw (independent) chuck with reversible jaws (8 TPI screws)<br />
* Tailstock drill chuck (max. 13 mm dia.)<br />
* Live center for tailstock (+ OEM fixed center) <br />
* Four way Tool Post (OEM Standard)<br />
* [https://www.amadeal.co.uk/acatalog/Quick_Change_Tool_Post_for_the_mini-lathe.html Quick Change Tool Post] + 3 tool holders<br />
* [https://www.amadeal.co.uk/acatalog/Fixed-Steady-for-Mini-Lathes-AMA_AC_CJ18A_FSRB.html#SID=145 Fixed Steady Rest]<br />
* [https://www.amadeal.co.uk/acatalog/Travelling-Rest-for-Mini-Lathes-AMA_AC_CJ18_TSRB.html#SID=144 Travelling Steady Rest]<br />
<br />
''You'll find all of the above on the shelf above the lathe, with the accessories in the wooden box, apart from the steadies, which live next to it. Change gears, spare parts, and most cutting tool tips/blanks are in labelled white rectangular tins behind the lathe.''<br />
=== Measuring Tools ===<br />
We have:<br />
* Various dial indicators - the one with the adjustable magnetic base stand is the most convenient for most lathe setup work.<br />
* 25mm micrometer (in little grey case)<br />
* Grey case containing set of measurement tools including dial calipers, micrometer, steel rule (metric & inch), engineers square, and a fish-tail gauge<br />
<br />
''We currently lack''<br />
* ''A tool height setting gauge''<br />
<br />
=== Hand Tools ===<br />
Some common tools needed for normal use are kept with the lathe, in or attached to the wooden accessories box:<br />
* 2 mm Allen key - adjusting cross-slide and compound gibs<br />
* 4 mm Allen key - quick change toolholder tool clamping screws + height adjust, tightening dials<br />
* 5 mm Allen key - four way toolpost tool clamping screws, engaging/disengaging threading indicator<br />
* 6 mm Allen key - locking/unlocking quick change toolholder<br />
* 8 mm spanner - locking carriage when 8 mm socket can't be used, locking gib adjuster nuts <br />
* 13 mm spanner - changing chucks, locking steady rest jaws<br />
* Very long needle nose pliers - for grabbing swarf safely, holding one end of emery cloth safely so you can keep your fingers away from the jaws, and extricating small objects from awkward places.<br />
<br />
== Change Gears ==<br />
[[File:BC puller 1.jpg|thumb|Custom puller for B-C stub shaft]] [[File:BC puller 2.jpg|thumb|Pulling the B-C stub shaft]]<br />
See "Conquest Super Lathe" manual ([[#Manuals|below]]), section '''4.7 Change Gears''', PDF pages 28-29, but see below for mesh adjustment. The LittleMachineShop.com "Mini Lathe User’s Guide" (also below) section '''Threading''' gives a far better explanation, with pictures and diagrams, but its for a lathe with a US 1/16 inch pitch leadscrew, not a metric 1.5 mm pitch one like ours, so you *MUST* ignore all the tables in that section, replacing them with metric mini-lathe (with 1.5 mm pitch leadscrew) equivalents. <br />
<br />
We have the following tooth count gears: 20,20, 30, 35, 40,40, 45, 50,50, 60,60, 80,80<br />
which consist of the OEM power feed gears + the metric change gear set. Apart from the metal 20 tooth pinions, they are all plastic, probably Delrin if the molded in 'POM' marking can be trusted, but possibly plain Nylon 6, and are metric Module 1.<br />
<br />
If we wanted to add the capability to cut US/Imperial threads we'd need to buy additional 55, 57 and 65 tooth gears, and possibly a 21 tooth metal pinion.<br />
<br />
CGTK's [https://www.cgtk.co.uk/metalwork/calculators/changegears/minilathe?gears1=20,20,30,35,40,40,45&gears2=50,50,60,60,80,80&gears3= Change Gear Calculator] ''(link preloaded with our gear list)'' is useful if you don't want to calculate the ratios from first principles. Not all suggested combos will physically fit.<br />
<br />
* Take care *NOT* to loose the keys in the A and D shaft keyways - turn each shaft till the keyway is up before removing the gear. <br />
* The B and C gears are coupled by a hollow stub shaft (with an integral key), which is so tight in the gears it has to be pressed or driven out - I've made a puller just for this task, kept in the change gears tin.<br />
* The center of the B-C stub shaft *MUST* be lubricated where it runs on its pin on the change gear banjo bracket, with grease or heavy oil. ''Seizure of the stub shaft due to running dry is a frequent cause of catastrophic mini-lathe geartrain failures!''<br />
* Don't get oil on the change gears as it can cause plastic gears to crack. Only PTFE drylube or plastic compatible white grease should be used on their teeth. <br />
* Adjust the B-C pin position in the straight slot first to set the C to D gear mesh, tighten its nut, then swing the whole banjo about the D shaft boss to set the A to B mesh, and finally tighten the banjo clamping nut.<br />
* Check both gear meshes have running clearance by turning the chuck by hand enough to complete one full turn of the leadscrew, and by attempting to turn the intermediate gear(s) to assess backlash, If excessive resistance is felt or if there's significant backlash, readjust the gears. If you have difficulty judging the mesh, a strip of 80 gsm copier paper (approx. 0.1 mm thick) wound into the meshing teeth before tightening the stud or banjo will give appropriate clearance once removed. Once setup, check the gears run quietly under power.<br />
* If the sum of the tooth counts C+D is the same as for the ones you just removed and they were correctly meshed, you don't need to move the stub shaft pin. If A+B is <u>also</u> the same, you don't need to move the banjo. e.g. If it was set up for 16:1 reduction power feed, 1 mm (40:60 - 50:50) for M6 and 1.5 mm (e.g. 40:60:40) for M10 pitches can thus be achieved by only swapping gears. <br />
<br />
''The change gears, puller, etc. and a box spanner for the banjo nut are kept in a white rectangular tin behind the lathe.''<br />
<br />
=== Power Feed ===<br />
When used for turning with power feed, the change gears should be set for a 16:1 reduction (A:20 : B:80 - C:20 : D:80) using the pair of small metal 20 tooth pinions and the 80 tooth plastic gears (largest in set), for a feed of 0.09375 mm per turn (1.5 mm/16). Unless continuing your threading project the next session, please re-fit the 16:1 power feed set after threading so the power feed is ready for use. <br />
<br />
* *ALWAYS* leave the feed direction selector lever in its neutral (no feed) position, and the half-nuts open after use.<br />
* *ALWAYS* check the carriage lock is disengaged before engaging power feed. Unlock the carriage after use. <br />
<br />
=== Threading Dial ===<br />
The threading dial is an aid to re-engaging the half-nuts at the right moment so the tool will retrace its previous path cutting deeper, rather than offsetting axially some fraction of the thread pitch and ruining your work. Its based on the concept of the lowest integer multiples of the leadscrew and thread ''(being cut)'' pitches that exactly match, but for mechanical simplicity it only covers certain selected multiples of the leadscrew pitch.<br />
<br />
We have a choice of three pinion gears:<br />
{| class=wikitable<br />
|+ Threading dial Pinion Gears<br />
|-<br />
! Teeth !! Colour Dot !! Usable lines !! OD gear !! Dist. per turn<br />
|-<br />
| 14 || Red || 1,7 || 7.51 mm || 21 mm<br />
|-<br />
| 15 || Orange || 1,5,9 || 8.05 mm || 22.5 mm<br />
|-<br />
| 16 || Green || 1,4,7,10 || 8.37 mm || 24 mm (2 mm/div)<br />
|}<br />
They are now colour coded, with a paint dot on the gear end face ''(the only non-wear surface)''. The 16 tooth one is normally left on the lathe, but disengaged when not threading to minimise wear on the lead screw. The others are kept in the Change Gear tin.<br />
<br />
There's a threading dial 'pickup' calculator here: https://www.cgtk.co.uk/metalwork/calculators/threaddialindicator <br />
<br />
Initially select ''Lathe:'' '''Custom''', and enter the following below:<br />
* ''Units:'' '''Metric'''<br />
* ''Lead Screw Pitch (mm):'' '''1.5'''<br />
* ''Thread Dial Indicator Gear Teeth:'' '''16,15,14''' <br />
* ''Lines on Thread Dial Indicator:'' '''12''' <br />
* ''Line Marking:'' '''Every Line Numbered'''<br />
Note the teeth list is entered in reverse order so the resulting table highlights any required pinion changes.<br />
<br />
N.B. The dial is only friction clamped to the pinion by its center screw. If you have any reason to suspect it may not be properly aligned: <br />
# With the power off and the carriage unlocked, engage the feed direction lever upwards. You'll probably need to turn the chuck by hand to get it to engage.<br />
# If the threading indicator isn't already engaged, loosen the threading dial support block bolt, pivot the block to engage the pinion with the leadscrew and retighten the bolt.<br />
# Engage the half nuts, again turning the chuck by hand till they drop in. <br />
# Turn the chuck a couple of turns, top towards you to take up any backlash, then lock the carriage, taking care not to push it left while locking it.<br />
# Loosen the screw securing the dial to the pinion.<br />
# Align the '1' line of the dial with the index line, by rotating the dial clockwise, then retighten the screw.<br />
# Don't forget to disengage half-nuts and unlock the carriage!<br />
<br />
The above instructions should result in the half-nuts engaging cleanly when exactly on any valid line when threading towards the headstock. If it is required to thread away from the headstock, there will be a slight offset from the line due to backlash between the spindle gear and leadscrew, so engage slightly early.<br />
<br />
Changing the pinion:<br />
# Loosen the threading dial support block bolt and disengage from the leadscrew.<br />
# Undo dial center screw, and remove it and the dial, dropping the old pinion out the bottom.<br />
# Oil the shaft of the new pinion with a drop of light oil and insert it from below, gear end down.<br />
# Refit dial and screw.<br />
# Check the dial and pinion turn freely with minimal resistance.<br />
# Align as above.<br />
<br />
== Tailstock and Steadies ==<br />
These are mostly used to support long work ''(long with respect to its diameter)'' to improve rigidity, increasing accuracy and reducing chatter. The Tailstock quill is also used with a drill chuck for drilling.<br />
=== Tailstock ===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock base]]<br />
The tailstock can be offset to turn shallow tapers between centers. We don't currently have the accessories to turn between centers, namely <s>a MT3 dead center for the spindle, or</s> any drive dogs for the work. Also realigning the tailstock after turning a taper can be a PITA. The photo shows the tailstock adjusting screw locations ''(C - Lateral, and D - Skew)'' and the block on the baseplate they engage with. Adjustments can only take effect when the tailstock locking lever is eased to take the pressure off the baseplate. As we don't have a MT3 center, one has to turn a fresh point on a test workpiece for a rough tailstock alignment reference. Fine alignment, to avoid inadvertent taper turning, can be done by mounting a long precision ground bar between the chuck (or preferably a center in the spindle), and a dead center in the tailstock and sweeping it with a dial indicator on the carriage. Finally a test cut should be taken at either end of a bar between centers, and the diameters checked with a micrometer. Assuming the bed has previously been properly levelled and shimmed to take out twist ''(not the case at RML as we don't have it bolted down)'', any remaining difference in diameter will be double the tailstock offset, smaller at the tailstock being offset towards the front. Fine adjustment cant be achieved by jacking with the screws, its best to ease the adjusting screws, bump the tailstock into alignment then take up the screws again, checking the alignment is maintained when the tailstock is unlocked and relocked. There is no vertical adjustment, though shims can be added between the tailstock and its base.<br />
<br />
==== Tailstock Quill ====<br />
There is a metric/imperial scale on the top of the quill, read against the end of the tailstock, for depth measurement when drilling. The tailstock quill has a 1.25 mm pitch thread and a 50 division dial. Each division is therefore 0.025 mm, and it only takes 4 full turns of the handwheel to move the quill 5 mm. <br />
<br />
To eject MT2 taper tooling and centers from the tailstock, wind the quill all the way in.<br />
<br />
N.B. The quill anti-rotation pin (dog-tip setscrew + locking nut in top of tailstock near to the quill lock) is only M5. It will sheer if a large diameter drill jams in the work. Please back it out clear of its keyway if using large drills, and use alternative methods of preventing chuck rotation. To re-engage it, crank the quill out till you can see the keyway, align it with the screw and screw in the screw till it gently bottoms out, then back it off a quarter turn. Try twisting the quill to check its properly engaged, then tighten the locking nut gently to hold the screw in position clear of the bottom of the keyway.<br />
<br />
=== Steady Rests ===<br />
We have two, both with brass tips that must be kept lubricated during use.<br />
<br />
The fixed steady mounts on the ways, and is most useful when turning longer work that wont fit through the spindle bore. Adjustment is critical, and the surface the tips run on must be smooth and concentric, as any misalignment that forces the work off center will result in the work wobbling in the chuck, marring it, with a high risk of it becoming un-chucked, which can be dangerous at speed.<br />
<br />
The travelling steady mounts to the headstock side of the carriage to locally resist the deflection of thin long work, due to the cutting forces. It only has two tips, to resist climb, and deflection away from the tool, and requires readjustment after every cutting pass.<br />
<br />
== Tooling and Tool Holders ==<br />
'''Key dimensional data:'''<br />
* The quick change holders accept up to 10 mm shank tools. <br />
* The four way toolpost has 50 mm long sides, a seat width of 15 mm and can clamp tools of up to 5/8" (15.875 mm) shank ''(check this)'', but the slot base is only 10.4 mm below the spindle center so cannot be used with >10 mm shank tooling unless it has a dropped tip. Large tooling with a centered tip is also problematic as you run out of height above the shank when trying to shim to match the spindle center height. <br />
<br />
===Quick Change Toolpost===<br />
I've got the quick change toolpost and toolholders setup for mostly easy use. The three toolholders came with cantilever height setting arms which historically haven't been installed as the supplied fixing screws were too short. That's all now sorted out and a HSS RH turning tool and a HSS hand-ground grooving/parting-off tool are now mounted in two of the holders and set to height. The third is kept free for other tools. <br />
<br />
The quick change toolpost has been modified with a spring to press the dovetail clamp outwards and help stop it twisting or flopping about to ease toolholder fitting and removal. The dovetail clamp (socket headed screw on toolpost side opposite dovetail) feels a bit stiffer than before, but will take less than half a turn to go from open (with the toolholder lifting out or dropping in easily) to fully clamped. As there is so much less clearance in the open position you should no longer need to wiggle the toolholder while clamping it to get a consistent height. If the dovetail clamp ever gets misaligned, twist it straight by eye, slacken off a bit further than usual to get a toolholder on, clamp it to align the dovetail then release, reseat the toolholder and re-clamp to ensure its at its preset height. You cant adjust the height by 'jacking' with the height screw due to its offset leverage. Instead, back off the height screw and hold the toolholder at the desired height while locking the dovetail clamp, then adjust the height screw (and locking nut) to hold it there, then check it doesnt change height significantly when you unclamp and reclamp the dovetail. <br />
<br />
Unfortunately the OEM height setting screws foul the toolpost locking nut handle. Currently, if you need to swap toolposts you will have to first remove the quick-change tool holder from the post. There is enough nut handle swing to allow the quick change toolpost to be unclamped and rotated to fine set the tool angle without removing the toolholder. It also seems the mating surfaces may be slightly out of square, as if you rotate the toolpost 90° or 180°, the nut swing may be insufficient to re-clamp it without removing the toolholder to do so. Add a M10 washer under the locking nut if the handle ends up pointing in an undesirable direction! A thin M10 washer is kept with the toolpost collar for this purpose, and will shift the handle position by about a third of a turn. <br />
<br />
''ToDo: Make a taller nut of a similar pattern, to clear the height setting screws.''<br />
<br />
===Four Way Toolpost===<br />
The OEM four way toolpost is significantly more rigid than the quick change toolpost + holders because it has fewer and thicker parts and less overhang. Therefore the four way toolpost should be used when using carbide tooling. It requires shimming under the tool to set the tip height to the spindle center height - see below. The tool shanks are mostly significantly less than 15 mm wide, so need to be centered under its clamping screws, tempting as it is push the shank in for full side contact with the toolpost. If possible clamp the shank with all three screws not just two.<br />
<br />
==== Shimming ====<br />
We typically only mount up to two tools, and want maximum rigidity, so use 50 mm x 15 mm shims, (the full seat area), preferably with deburred edges and radiused corners so they aren't a hazard to the operator.<br />
<br />
We have pre-cut and marked shims of the following thicknesses: <br />
* 1x 3.23 mm, 2.42 mm, 1.56 mm, 0.32 mm, and 0.25 mm<br />
* 2x 1.00 mm, 0.77 mm, 0.12 mm, 0.11 mm, 0.10 mm and 0.05 mm<br />
* 4x 0.53 mm<br />
<br />
Our shims are mostly found materials (hence the awkward thicknesses) and are mostly a mixture of aluminium and steel, with a couple of GRP ones. The toolpost seat '''<u>must be absolutely clean</u>''' to avoid embedding debris in the aluminium or GRP shims, to get a consistent height and avoid tilting the tool - wipe it every time you change a tool! Put the thin shims at the bottom of the stack to avoid the tool shank edges creasing them. Shims are kept in a little yellow plastic box with a clear lid, near the carbide tools case.<br />
<br />
I made a tool height setting gauge (T shaped black acrylic with steps in its sides) which can be used to check the tool tip height matches the spindle center height using either the flat of the ways or the saddle as a reference. The tool tip should just fit under the lip of the appropriate step, with the T arms across the ways flats or on the saddle. It is kept in the box with the carbide insert tools.<br />
<br />
''ToDo:'' <br />
<br />
* ''Cut more shims neatly, mark them with their thickness.''<br />
* <s>''Do test cuts and start noting shim stack-ups for various tools.''</s><br />
* ''Organise shim storage!''<br />
<br />
=== HSS Tools ===<br />
[[File:Tool Bit Geometry.jpeg|thumb|Single point cutting tool geometry]]<br />
Our HSS tools are made from 8 mm square bar stock, hand-ground to tip profile in-house. See LittleMachineShop's [https://littlemachineshop.com/images/gallery/instructions/grindingtoolbits.pdf Grinding Tool Bits] notes. <br />
<br />
I've installed our usual HSS LH turning and parting off tools in two of the quick change holders and set the heights correctly. There are a couple of other HSS tools or tool blanks knocking about. Taking heavy cuts turning steel (even with good cutting oil) blunts HSS tools fairly quickly, which are time-consuming to re-sharpen nicely without a dedicated tool & cutter grinder with appropriate jigs. Its worth noting that the usual 'speeds & feeds' tables are commonly based on surface speeds expected to give a half hour (active cutting) tool life before resharpening.<br />
<br />
I touched up the LH turning tool by lapping on wet & dry (silicon carbide) paper on glass (Aka: [https://en.wikipedia.org/wiki/Scary_sharp 'Scary Sharp']) working upwards through the grits 200, 400, 600 and finally 1000, initially 'bluing' the surfaces to be lapped with a marker pen to see which areas needed taking down more. The end of the tool was significantly uneven so I touched that up freehand on the bench grinder to flatten it when it became apparent that 200 grit lapping wasn't cutting where it needed to. There was an existing micro-bevel on the leading side, which I kept. Finally I 'dubbed' the leading corner vertical edge on the 1000 grit to give it a very slight nose radius. A test cut on brass gave a very nice finish when turning.<br />
<br />
''Ian B has purchased some spare 8mm HSS tool blanks - talk to a lathe trainer if your proposed lathe work needs custom ground HSS tooling.'''<br />
<br />
=== Brazed Tungsten Carbide Tools ===<br />
Somewhat of a half-way house between hand ground HSS tooling and insert tooling with the disadvantages of both and some more besides - e.g. they are much harder to sharpen. So why do we bother? Some tool geometries would be awkward and tedious to hand grind, and Chinese import brazed carbide tooling is about half the price of similar HSS tooling, and far more readily available. Also, for space constrained tooling like boring bars, if you want carbide, for insert tooling, the size of the insert and its clamping seriously limits the minimum hole diameter you can work in. I have purchased a set of 3/8" shank brazed carbide tipped boring bars, but we currently cant sharpen them, due to lack of a diamond grinding wheel. <br />
<br />
=== Tungsten Carbide Insert Tools===<br />
Decoding ISO insert tooling part numbers: https://www.cutwel.co.uk/blog/learn-the-turning-tool-iso-code-system<br />
[[File:Carbide set.jpg|800px|thumb|left|Our set of Tungsten carbide insert lathe tools (before the new inserts were fitted)]]<br />
<br />
{| class=wikitable<br />
|+ Tools, left to right, (+ last across top):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| SSKCR0610H06 || 75° through boring || SCMT06204 || Long || 6 || 6.34 || ''4.33''<br />
|-<br />
| SSSCR0610H06 || 45° deep facing, internal chamfering || SCMT06204 || Long || 6 || 6.13 || ''4.58''<br />
|-<br />
| SWUCR0610H05 || 93° boring, deep facing || WCMT050308 || Long || 6 || 6.22 || ''4.48''<br />
|-<br />
| SWGCR0810E05 || 90° RH turning & facing || WCMT050308 || Short || 8 || 8.25 || '''2.45'''<br />
|-<br />
| SSSCR0610E06 || 45° turning, chamfering || SCMT06204 || Short || 8 || 8.75 || ''1.93''<br />
|-<br />
| SSBCR0610E06 || 75° RH turning, chamfering || SCMT06204 || Short || 8 || 8.72 || ''1.98''<br />
|-<br />
| LW0810R-04 || 60° external threading || JCL15-120 || Short || 8 || 7.44 * || ''3.28''<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || 8.23 || ''2.5 ?''<br />
|-<br />
| LN0813R-04 || 60° internal threading || JCL15-120 || Long || 7.95 || 7.44 * || ''3.28''<br />
|}<br />
<br />
{| class=wikitable<br />
|+ More Tools, (loose in tin):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || ~8.5 (not in use) ||<br />
|-<br />
| [https://www.glanze.co.uk/product/glanze-12-mm-60-degree-metric-internal-threading-tool/ Glanse SIR0012K11] || 60° internal threading bar || 11IRA60 || Long || 12 dia || ??? || ???<br />
|}<br />
''Shim stack heights in bold are tested, in italic are only calculated.'' ''Tip heights marked * are with new JCL15-120I inserts. The single remaining plain JCL15-120 insert has a slightly higher tip height.''<br />
<br />
Carbide tooling typically requires two to three times more speed than HSS and at least a couple of 'thou' depth of cut for best results.<br />
<br />
Chatter can rapidly kill carbide tooling by chipping the cutting edge. To improve rigidity and reduce the risk of chatter, the cross-slide and compound gib screws need to be well adjusted so there is minimal play in the slides, tool stick-out should be minimised, the four way toolpost should be kept over the cross-slide, and the work should be kept close to the chuck (or otherwise supported by tailstock or steady rest) to avoid excessive deflection.<br />
<br />
Thermal shock is almost instant death to carbide, and when dry cutting the insert tip can run very hot, so do not add extra cutting fluid manually during the cut. Pre-apply what you need, evenly, before starting the cut.<br />
<br />
Parting off or facing to center is high risk - if the tool tip is even slightly below center or if tool or work deflection takes it below center, the work will tend to climb over the tool tip as the cut approaches center, breaking the insert. To avoid this, the tool should be shimmed slightly above center, sufficient to allow for work and tool deflection, and unless very close to the chuck, a steady should be used. Its often preferable to part to a couple of mm dia. remaining then stop and saw through the remainder. Parting off hollow parts is much lower risk.<br />
<br />
Further investigation of the Tungsten carbide insert tool height situation is not encouraging - the so-called 'set' in question does not have a consistent tip height ''(see above table)''! In a real set, the insert seats *should* be machined allowing for the insert thickness to bring all the cutting edges to the same height with respect to the shank underside. However if you place them tip to tip on a table its easy to see there is considerable height variation, so they need to be individually shimmed (or at best, one machined shim will only be right for two or three tools). At this time we don't have dedicated shim stacks for each tool.<br />
<br />
A 2.42 mm thick shim brings the SWGCR0810E05 90° RH turning & facing tool almost exactly to center height, and good results were obtained turning 1" steel pipe. However facing 50mm steel bar stock to center found it to be slightly low, leaving a fractionally under 0.05 mm 'pip' so it needs another 0.03 mm to bring it fractionally above center. Fractionally too high is generally preferable to fractionally too low, due to tool deflection, so adding an 0.05 mm shim to the stack should produce optimum results.<br />
<br />
==== Inserts ====<br />
Ian B has purchased the spare inserts we needed in sets of five. He even was able to get the CK3 parting-off inserts which had been difficult to source!<br />
<br />
Inserts used in above tool set:<br />
* 3x SCMT06204 (square, indexable) https://www.rdgtools.co.uk/acatalog/SCMT-06-Carbide-Insert.html<br />
* 2x WCMT050308 (triangular, indexable) https://www.rdgtools.co.uk/acatalog/WCMT-05-T3-08-5XTIP-8813.html<br />
* 2x JCL15-120 (60 deg threading point) https://www.rdgtools.co.uk/acatalog/X5-JCL-15-120L-THREADING-TIPS-60-DEGREE--X5-TIP---23455.html<br />
* CK3 (parting off) https://www.rdgtools.co.uk/acatalog/CK3-CARBIDE-TIPS---PARTING--BOX-OF-5PCS--9437.html<br />
<br />
Inserts used in other tools:<br />
* 1x CK3 (as above) also missing from spare parting off tool<br />
* 1x 11IRA60 in Glanse threading bar + 1x spare<br />
<br />
=== Drills ===<br />
Various sizes of center drills are kept in a plastic bag next to the wooden accessories tray. There's also a small box of 2.5 mm center drills.<br />
<br />
We have a set of 11 TiN coated HSS drill bits from 1.5 to 8 mm, (in a cylindrical plastic index box) for tailstock drilling of brass, aluminium and non-abrasive plastics. To keep them sharp enough for the precision work we expect from the lathe, please don't use them for steel or reinforced plastics, and don't borrow them for non-lathe use. Metric and US [https://littlemachineshop.com/reference/numberdrillsize.php numbered]/[https://littlemachineshop.com/reference/letterdrillsize.php lettered] general use HSS drill bits are kept in two red metal index boxes next to the drill press.<br />
<br />
== Using the Lathe ==<br />
=== General ===<br />
A cutting speed chart for HSS tooling, published by Model Engineer magazine can be found [https://www.model-engineer.co.uk/sites/7/documents/cutting%20speed%20chart.pdf [here<nowiki>]</nowiki>]. The second row is the target feed rate and the rest of the chart, apart from the diameter column is RPM.<br />
<br />
For carbide tooling cutting iron and steels, recommended speeds are generally three times higher than for HSS, but the CJ18A 2500 RPM max. spindle speed (in high gear) means you can only reach the optimum speed range for over 15 mm dia work. For small diameter work, HSS tooling may well be a better choice.<br />
<br />
An online metric speeds calculator is here: https://www.cgtk.co.uk/metalwork/calculators/cuttingspeeds <br />
<br />
How to do the maths to calculate speeds and feeds: https://www.cutwel.co.uk/blog/speeds-feeds-made-easy<br />
<br />
Making dimensioned parts is primarily done by touching off the tool tip on a reference surface (with the lathe stopped, turning the chuck by hand), zeroing the handwheel dial, then manually counting turns and divisions. When backing off the tool its best to do so by exactly one whole turn so you don't forget the previous dial position. Stopping and measuring the work before taking the final cuts is essential if high accuracy is required. ''I've changed out the dial setscrews for flat tip ones with a tiny slug of solder under them so the dials are now friction fit on their shafts. i.e. if you hold the handle firmly taking up the backlash in the direction of cut, you can zero the dial just by grabbing and twisting it.''<br />
<br />
Carriage movement is less easy to measure as the handwheel is uncalibrated and advances an awkward bit over 19.2 mm per turn. Your options here when shoulders or other features must be exactly positioned are, in order of increasing accuracy: <br />
* Use measuring instruments, scribe the work at the desired length then work to the scribed line. Its often convenient to black the work with a permanent marker, then scribe with the tool tip, turning the chuck by hand.<br />
* for short distances, lock the carriage and use the compound, set parallel to the work<br />
* Set up a long travel dial indicator to measure carriage motion. <br />
N.B. with the leadscrew stopped, and the threading dial engaged, with its default 16 tooth gear, it will make one turn for every 24 mm of carriage movement (2 mm/div). This isn't accurate enough for positioning but is sufficient to check you aren't out by a whole mm or more.<br />
<br />
Do not allow any solvents to contact the chuck guard clear plastic as it will make the plastic brittle, or even craze it, and try to avoid melting it with the work light!<br />
<br />
=== Slide Locks ===<br />
* The carriage can be locked to the ways using the M5 hex screw through the top of the saddle to the left of the cross-slide. Double check the leadscrew is disengaged and the half-nuts open before locking it. Lock it when facing.<br />
* The cross slide can be locked by a M4 socket headed cap screw just in front of its middle gib screw. Locking the cross slide is helpful when turning very shallow conical features where the cross slide handle is in the way of the compound.<br />
* The compound slide can be locked by a M4 socket headed cap screw in line with the edge of the toolpost mount on the side with the gib adjustment screws. In normal use it should be kept backed off half a turn but it is desirable to tighten it for parting off operations to keep the resulting end faces flat.<br />
<br />
=== Chucks and Chuck Jaws ===<br />
==== Terminology ====<br />
* Inside jaws have steps on the outside to grip the ID of hollow work, but can also be used as outside jaws on small diameter parts (i.e. that fit through the spindle). <br />
* Outside jaws have steps on the inside to grip the OD of the work.<br />
* Universal chucks have a scroll plate with a spiral screw thread that moves all the jaws.<br />
* Independent chucks have individual adjusting screws for each jaw.<br />
<br />
==== The Chucks ====<br />
* The three jaw universal chuck can only grip near round or hexagonal work, which it centers, but its concentricity is not perfect so e.g. if you reverse the work and continue turning at the same diameter from the other end, you will see a line where the turned surfaces meet. It has separate sets of inside and outside jaws, and we normally keep the inside set installed to use as outside jaws for small diameter work.<br />
<br />
** Our jaws are individually numbered, stamped in the groove. They must be fitted in the correct sequence. The jaw slots are not clearly marked. Lowest runout for small dia. parts is achieved if you fit the jaws with #1 anticlockwise of the makers mark, then continue anticlockwise for #2 and #3.<br />
** A large strong rubber band is a great help getting all the jaws started on the scroll together - with slots #1 and #3 above the centerline and the scroll thread outer tip between #1 and #3, insert jaws #1 and #2 and put the rubber band round them to keep them in their slots. Insert jaw #3 and stretch the rubber band over it to hold it up into its slot. If the scroll was positioned correctly, all jaws should be at the same initial radius. The jaws can now be cranked in with the chuck key and they should all engage in step so they meet in the middle.<br />
:: ''Mini-lathe.com have the best instructions for [https://www.mini-lathe.com/mini_lathe/chucks/chucks.htm#Installing_Chuck_Jaws changing the jaws].'' <br />
<br />
* The four independent jaw chuck can grip most roundish or squarish work, which can either be carefully centered by the user, or deliberately gripped off-center. <br />
** Its jaws are reversible so can be swapped from inside to outside by simply cranking each jaw out and reinserting it the other way round, one at a time. DON'T move the jaws to different slots as they are likely to bind.<br />
** When setting up to face the sides of rectangular objects held crossways, it may be helpful to use both inside and outside jaw orientations, in symmetrical opposing pairs.<br />
** Its screws move their jaw 1/8" (3.125 mm) per turn<br />
<br />
* The jaws must '''never''' protrude from the chuck OD by more than one step, and for safety, its preferable they don't protrude at all, as they make the gap between the front of the bed and the chuck body an even more unforgiving meat grinder, and as the number of teeth engaged with the scroll or screw decreases, they loose strength, just when you need it the most to grip larger/heavier work. <br />
<br />
''Neither chuck is well suited to gripping tapered work safely. When seating work that doesn't quite fit through the chuck bore (which is larger than the 20mm spindle bore limit), be careful that it isn't seating on the chamfered edge of the chuck bore as it is far to easy to get the work slightly cocked so it doesn't run true.''<br />
<br />
==== Changing Chucks ====<br />
* When changing chucks, use the small grey plastic mat to protect the ways under the jaws in case you drop the chuck.<br />
* The spindle nose has two patterns of holes - the three hole pattern is for the three jaw chuck and the faceplate, and the four hole pattern is for the four jaw chuck. One hole is shared between the patterns, and is marked on the spindle nose.<br />
* To fit a chuck:<br />
** First check that the spindle nose and chuck back and recess are free of swarf, grit or other debris. Any foreign objects will tilt the chuck causing excessive runout and may mar the surfaces.<br />
** Remove the nuts and split lock washers from its studs, line its studs up with the hole pattern (preferably with the stud nearest anticlockwise to the makers mark through the marked spindle hole), fit and hold it in place with your right hand, and with your left, get the lock washer and nut on the top stud, and take up the slack.<br />
** One one nut is on, you no longer have to worry about dropping it, and can work round fitting the remaining washers and nuts, taking up the slack on each as you fit it. <br />
** Next, work round again getting them all finger tight, then tighten them gently, and finally work round fully tightening them. <br />
* Removal is the reverse of refitting. Put the washers and nuts back on the chuck's studs so they don't get lost.<br />
<br />
=== Faceplate Work ===<br />
Faceplate work is probably the most dangerous operation you can (or rather should) perform on a lathe. The working area is a large diameter spinning surface with protruding clamps to fixture the part that it is impractical to guard. Protruding clamps, studs, nuts etc. are very difficult to see at speed.<br />
<br />
'''Treat the faceplate with great respect and caution if you wish to continue to be able to count to ten on your fingers!''' <br />
<br />
The 65 mm cross-slide travel vs the 80 mm faceplate radius is a serious limitation that may require creative compound, toolpost and tool setups for larger parts, and doing full face cuts in two sections.<br />
<br />
''It is common practice to skim the faceplate to ensure it runs true. We have not (yet) done this, and wont till the spindle is in better bearings and the nose reground to minimise runout.''<br />
<br />
==== Clamping ====<br />
Open ended/sided clamps should be oriented so that cutting forces drive the work towards the clamping bolt/stud, not out from under the clamp. Minimize the protruding length of thread past the clamping nut, if necessary using sacrificial bolts or studs you can cut to length, or even using a long M8 stud for one of the faceplate mountings, so you can get a clamp nearer to the faceplate center. Double-check all clamps are secure, manually turn the faceplate to check the work and clamps clear the ways, top-slide and toolpost, and stand out of the 'line of fire' (a disc extending from the faceplate) when spinning up the work for the first time. <br />
<br />
If you need to machine close to a clamp, consider marking a safe limit circle on the faceplate and work with a marker pen to make it easier to see how close the cutting tool is to crash disaster. <br />
<br />
I strongly advise reading chapter two of Tubal Cain's book "Workholding in the Lathe" several times before your first faceplate setup, and if possible get another experienced lathe user to check your first few setups before spinning them up.<br />
<br />
==== Chuck Guard Removal ====<br />
The faceplate is too large diameter to fit under the chuck guard, but the guard has an interlock switch wqhich must be closed for the lathe to run. The guard is now fitted with wing nuts so it can be removed allowing the the interlock switch to close when using the faceplate. It *SHOULD* *ALWAYS* be refitted if a chuck is fitted, except when turning work too large to clear the guard. <br />
<br />
''The chuck guard is primarily there to make it very difficult to start the lathe without removing the chuck key and to reduce the area of large diameter spinning surface exposed. It may slow down the projectile if a chuck sheds a jaw but is unlikely to stop it. Also it serves to contain coolant spray spun off the chuck. As we don't use flood coolant this usually isn't an issue for us. As setting up for faceplate work doesn't use a chuck key, and the most hazardous zone is the face of the faceplate, with its spinning projecting clamps, with full access required for machining operations, which a guard would not cover, the consensus is that removing the guard is an acceptable risk.''<br />
<br />
=== Turning and Facing ===<br />
We are getting good results in aluminium, brass, and even steel using HSS cutting tools in quick-change tool holders, and the ~ 94 um/turn power feed. Unfortunately due to lack of rigidity in both the machine and smaller diameter parts, if you don't want the outer end to be over diameter, a light final cut and multiple 'spring' passes will probably be required.<br />
<br />
For aluminium, a sharp HSS tool and 0.5 mm (20 div) depth of cut gives good results with power feed for rapid stock removal. Its also easy maths as each cut takes ~ 1 mm off the diameter. Finish cuts should be much finer, 0.1 mm (4 div) is 'in the ballpark'.<br />
<br />
For steel, using carbide insert tooling, a 0.25 mm (10 div) depth of cut is more appropriate, and with pre-applied cutting oil, gives reasonable results with power feed if you use enough speed. The maths is not quite so easy as you are only taking 0.5 mm off the diameter per pass. Again, use finer finish cuts but try to plan your cuts so the final cut is still cutting, not smearing the surface!<br />
<br />
When facing or parting off, some skill is required to turn the cross-slide handwheel steadily to get a decent finish and to avoid shock-loading the tool tip. Increasing the spindle speed in one or more steps to keep up with the reducing diameter is advisable, but avoid speeds that cause resonances (resulting in chatter). When parting off, small through-hole parts may be caught on a thin rod chucked in the tailstock, and pre-positioned inside the work with its tip right up to the parting off position.<br />
<br />
==== Using the Steady Rests ====<br />
For the fixed steady rest, see Blondihacks' Lathe Skills #26 - How To Use a Steady Rest! [[#Youtube_Playlists_&_Videos|{below}]]<br />
<br />
Ours doesn't have ball bearing fingers, so a smooth surface on the work and adequate lubrication are essential. The thumbscrews can only tighten the fingers, so for small adjustments outwards you need to either slack off the clamping nuts or ease them slightly and use a drift against the back of the finger's slot. Once set, check the chuck still turns freely.<br />
<br />
The traveling steady rest needs to run on a machined surface, so at least for the first pass, must follow the tool, so its difficult to avoid using more compound slide overhang than is desirable. An initial surface should be cut next to the chuck or tailstock center before fitting the steady rest.<br />
<br />
Both are a PITA to fit - the fixed one has to have its clamping post inserted up through the bed, and the supplied spanner is useless near the headstock, and the travelling one's mounting holes on the saddle almost invariably need swarf picked out of them.<br />
<br />
==== Turning Between Centers ====<br />
<s>Using a MT3 to MT2 reducing sleeve, the MT2 dead center can be fitted in the spindle.</s> ''Currently the MT3 spindle taper is compromised.'' Alternatively, a soft center can be turned immediately before use in the three jaw chuck, but that must have its 60° point re-cut to concentric if the chuck is disturbed, and needs to be either large enough to bear on the chuck body, or must have a lip to bear on the end face of the jaws to take the axial thrust. Recutting the center is a PITA, as the compound angle must be set to 30° anticlockwise, then reset to a true 0° afterwards. Maybe a right-hand 30° end angle zero rake form tool is the answer, or use the carbide insert tool SSKCR0610H06 as a form tool with the toolpost rotated 15° anticlockwise.<br />
<br />
With the MT2 live center in the tailstock quill, this gives us a center either end of the work to hold it.<br />
<br />
We also need a drive dog similar to [https://littlemachineshop.com/products/product_view.php?ProductID=4473&category=1 this], and the corresponding drive post to bolt to the spindle nose. I have some 25mm bore thick wall iron pipe, which should do nicely. Lengths of the dog's straight tail and of the post TBD after I check how much the center protrudes. N.B. its recommended to tie the tail to the post to keep them in contact so they don't slam. ''Currently we will need to drive from the chuck jaws. Possibly use the exterior jaws with a short soft center gripped on the inside end and drive from the highest step.''<br />
<br />
=== Drilling ===<br />
Always start with a center drill so deflection of longer bits doesn't start the hole off-center. For larger bits (> 5 mm), first drill to the web size, then to final diameter. For a precision hole, drill slightly undersize and ream to final diameter. ''Supply your own reamers!''<br />
<br />
Caution: See note about the quill anti-rotation pin in section [[#Tailstock Quill|Tailstock Quill]] above.<br />
<br />
=== Boring ===<br />
Caution: As the spindle doesn't extend right through the headstock housing, if boring in a through hole, chips tend to fall out the back and tumble in the spindle bore till they fall into the change gears. To avoid this, one should plug the spindle bore with a wad of paper towel or rag and when cleaning up afterwards, use a rod to push it through towards the tailstock, with the chuck jaws (if fitted) wound clear of the spindle bore.<br />
<br />
A swivel bladed hole deburring tool (pale blue handle) can be found in the main room on the windowsill behind the drill press.<br />
<br />
A couple of boring jobs have been bodged with an awkwardly angled turning tool and achieving acceptable effective rake with enough clearance to reach deep enough into the hole has been problematic. I reviewed the tools we had and found none suitable for starting out in a 13mm bore, the max diameter we can (easily) drill. I therefore decided to buy a set of boring bars and make a holder for them. I had difficulty finding anything affordable under 10mm shank - the best low cost option was a [https://www.amazon.co.uk/dp/B07P5LGVBX set of nine 3/8" (9.525 mm) shank brazed carbide tipped boring bars], which would be close to the max capacity of the quick change boring bar holder - if we had one! Unfortunately this holder for our specific toolpost is difficult to find except in a toolpost bundle. Another annoyance is the variable tip height of the set, varying from 1.8 mm to 2.8 mm above the center of the shank.<br />
<br />
I therefore decided to make a boring bar holder of the [https://littlemachineshop.com/products/product_view.php?ProductID=1700 Littlemachineshop.com (USA) style] for use in the four way toolpost, as the additional rigidity will certainly help. Starting with a slightly over 50 mm length of 16 mm aluminium square bar and using the four jaw chuck , both ends were faced and an attempt was made to find its center and center drill it. It was then drilled out to ~9.8 mm after much drama due to blunt drills and drills that cut ~1mm oversize. Too big, but beggars cant be choosers as we didn't have a boring bar holder or a 3/8" reamer. Unfortunately the final hole ended up significantly off center. It was then chucked crossways and ~1 mm skimmed off its thickest side to gain clearance to allow it to be shimmed to height, then one side was slit lengthwise manually with a hacksaw.<br />
<br />
It was fitted to the for way toolpost and loaded with a booring bar, which clamped firmly. A 0.86 mm shim stack brought the tip of the largest boring bar almost spot on center height, with the difference easily accommodated by twisting the tool slightly. The three jaw chuck was then remounted, and a piece of iron pipe chucked for a test. It cuts well and leaves a decent surface finish.<br />
<br />
''The boring bar setup is a work in progress - talk to me before attempting to use them if you have a project that would benefit from boring..''<br />
<br />
ToDo: get something that can sharpen tools tipped with this grade of carbide - it needs some sort of diamond (or possibly CBN) wheel as green grit silicon carbide does little more than polish it. ''N.B. diamond wheels are rapidly eroded by grinding steel, so the supporting steel seat must be undercut with a regular grinding wheel before the diamond wheel can contact it.'' <br />
<br />
We'll also need 50 mm square sheet shims to fit under the toolpost to gain clearance in the toolpost above the tool or toolholder. A 2.4 mm shim would give us about the same above and below spindle center height, and we probably need a small selection of thinner ones.<br />
<br />
=== Thread Cutting ===<br />
The objective is to cut a thread that complies with the ISO metric thread profile. Our lathe is not currently equipped to cut non-metric threads, (with the exception of BA which have pitches based on metric threads of that era).<br />
<br />
[[File:ISO and UTS Thread Dimensions.svg|frame|center|Metric Thread Profile - from the geometry, H is ~86.6% of P]]<br />
<br />
Metric thread data - See 'Preferred Sizes' at: https://en.wikipedia.org/wiki/ISO_metric_screw_thread<br />
<br />
See "Mini Lathe User’s Guide" section '''Threading''' for general techniques *ONLY*, and above for change gears and threading dial setup.<br />
<br />
Amadeal specify the max. thread pitch as 2.5 mm. Any thread pitch greater than 1.5 nn requires the change gears to gear up. When gearing up it is desirable to distribute the ratio as evenly as possible over the two pairs of gears in the geartrain to avoid excessive tooth loading.<br />
<br />
==== External Threading ====<br />
Initially turn work to required Major Diameter, set up change gears and threading tool, touch off on the work, zero the top and cross slide dials, and do a 'scratch' pass to check the pitch. Back off the tool, return the carriage, and re-engage the half nuts on a valid dial line clear of the end of the thread then immediately stop the lathe, and hand turn the chuck till the tool tip is (hopefully) over the scratch to check the thread pickup. If all is good, return the carriage again, restart the lathe and start cutting your thread. <br />
<br />
Methods of doing so vary depending on the size of the thread and toughness of the metal, but straight-in plunge cutting is generally to be avoided as has the highest cutting forces, and does not reliably keep the carriage (and top-slide if set parallel to the work) loaded to avoid pitch errors due to backlash. <br />
<br />
If leaving the half-nuts engaged and reversing the lathe to return to the start of the thread for the next pass, its absolutely essential to back the tool out of the thread for the return pass as it will not follow the path of the cutting pass due to backlash in the geartrain, leadscrew mounts and half-nuts.<br />
<br />
==== Internal Threading ====<br />
''<nothing here yet>''<br />
<br />
== Cutting fluids ==<br />
=== Why bother? ===<br />
[https://youtu.be/mRuSYQ5Npek Watch this video] and contemplate what's actually happening to that thin ribbon of metal being removed. Most of the lathe's motor power is being turned into heat by internal friction in the chip being removed in the zone around the cutting edge, and surface friction at, and immediately behind the cutting edge, near-instantly heating the chip by up to several hundred degrees. Reducing the surface friction using a suitable cutting oil reduces the strain on the machine as a whole, and reduces workpiece and tool heating (and thus expansion) with consequent improvements in maximum usable feed and depth of cut, surface finish and accuracy. It also drastically increases the life of the cutting edge.<br />
<br />
=== Practicalities === <br />
We don't have a coolant system for the lathe and *really* don't want the maintenance hassles of using soluble cutting oil/coolant as if used infrequently its a PITA to keep recirculated high water content cutting fluids from going rancid and stinky, and they can also rust the ways, so even a total loss gravity feed system is problematic. Therefore if dry machining doesn't give a good enough finish, we tend to use oil applied topically, by hand to the work. <br />
<br />
* Hard brass is typically free-turning without oil, however some light oil for the final cut can improve surface finish, but with the disadvantage that it will increase loose chip buildup on the tool as hard brass typically forms short spalls or splinters rather than curly chips.<br />
<br />
* Many Aluminium alloys tend to be gummy, and Paraffin or other mineral spirits mixed with a little oil can help prevent the aluminum welding to the tool edge. WD40 will do at a pinch, but its messy to apply from a spray can.<br />
<br />
* Steel really needs *GOOD* cutting oil. Lard oil is the traditional choice for steel. If there are any objections to lard oil, we should bite the bullet and get some commercial dark high Sulphur cutting oil, but beware, many such oils use an additive package that includes lard oil.<br />
* Cast iron (except ductile) should be cut dry, as the carbon micro-inclusions self-lubricate it, and the carbide in the dust (primarily Cementite) are very abrasive, so tend to form a grinding compound if mixed with oil. <br />
<br />
I've sorted out an oil pot lid with a 1/2" brass collar soldered in to give a nice smooth sided hole, for ease of use and to minimize the risk of spills when using a brush to apply cutting oils, and got some dirt-cheap brushes. It fits Shippam's paste (and similar own-brand spread) jars and I've found several jars and ordinary lids to seal them for storage. Unfortunately it isn't the easiest to get this type of jars' lids back on square so they seal properly, and if you over-tighten them and there's a temperature change, they can be a total <expletive> to reopen. Using the rubberised handles of a large pair of pliers to grip the jar lid just above its rim is the best option, and avoids damaging the lids.<br />
<br />
''N.B. For the smaller brushes, the glue holding the bristles in is attacked by paraffin. To prevent loss of bristles, crimp the aluminium ferrule of each new brush of this type before use.''<br />
<br />
We have, in labelled jars:<br />
<br />
* Sulphurised Lard oil thinned with paraffin. Best choice for heavy cuts and threading in steel but stinky.<br />
* Lard oil thinned with paraffin. Good for steel and acceptable for softer copper alloys<br />
* Paraffin with a trace of light oil. Good for aluminium, and can help prevent squealing chatter on finish cuts in brass.<br />
<br />
I've also got some paraffin wax (in the form of a stubby candle), which can be applied lightly (under power) to brass and aluminium stock especially on the finish pass. It makes less mess than oil but unfortunately tends to build up on the tool tip, making it difficult to 'work by eye' without frequent pauses to clean the tool tip.<br />
<br />
We've also got a tin of [https://www.rocol.com/products/rtd-compound Rocol RTD cutting compound], which is a thick paste. Its highly recommended for drilling and tapping steel (in the drill press or by hand), but as a paste, is less useful for general lathe work unless thinned to a fluid consistency, e.g. with paraffin or white spirits. OTOH its certainly worth trying for high speed facing steel as it is less likely to get flung off.<br />
<br />
== Cleaning and Maintenance ==<br />
Swarf is a significant cut hazard to the operator, especially stringy swarf from cutting steel. Never touch it bare-handed - always use a tool e.g. a brush, or a hook, or needle nose pliers for grabbing long swarf.<br />
<br />
* After use, brush all swarf off the toolholder, compound and cross slide etc. ways and leadscrew. Ian B has blocked off the opening at the headstock end of the rear splashguard (to try to keep swarf out of the motor), so one must sweep the swarf towards the open tailstock end and catch it in a dustpan or similar. Preferably, also thoroughly clean out the chip tray under the lathe, but at least sweep out visible swarf.<br />
* Wipe up any cutting fluid residue and re-lubricate affected sliding surfaces with way oil.<br />
* Do not solvent clean the chuck guard, as it will make the plastic brittle, or even craze it. Water with a little detergent is permissible for cleaning it, with the guard totally removed from the lathe.<br />
<br />
Before engaging the half-nuts for power feed/threading, check the leadscrew is clean! ''Best cleaned under power, with a toothbrush.'' <br />
<br />
'''Caution:''' The traverse gears behind the carriage handwheel are in an open-backed housing and tend to become packed with swarf! Swarf buildup here will result in jerky carriage movement. Clean out as much as you can with a toothbrush ...<br />
<br />
===Lack of lubrication and/or swarf or dirt build-up can be disastrous===<br />
* If using the change gears/power feed, lack of lubrication of the B-C stub shaft center pin or either leadscrew end bearing can result in seizure and immediate destruction of one or more gears in the gear train or worse. <br />
* Small pieces of swarf can get between the saddle and ways, or into the slides degrading accuracy, possibly permanently if hard swarf scores them, or jamming them. The carriage handwheel gears behind the apron are notorious for accumulating swarf, and swarf buildup on the leadscrew can prevent the half-nuts engaging properly, resulting in scrapped work, and possibly stripped half-nuts. <br />
* Metal swarf can get into the motor (''though Ian B has modified the rear chip catcher to reduce the risk)'' or into the control box via the leadscrew, and short-circuit stuff. At best it will blow the fuse and need a strip-down to clean it out, at worst it may require a replacement [https://www.amadeal.co.uk/acatalog/Speed-Control-Circuit-Board--12amp-AMA_SP_CJ18_SCB12.html#SID=12 speed controller] ''(currently £96)'' and/or [https://www.amadeal.co.uk/acatalog/550W-motor-for-CJ18A-Mini-Lathe-467.html#SID=240 motor] ''(currently £105)'' and possibly other electrical parts. We should probably fit a [https://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C3-Mini-Lathe-Spares/C3-256-Leadscrew-Grommet-Dustproof-Cover C3-256 Leadscrew Grommet] to keep swarf out of the control box, as it tends to drop onto the 'Filter' board which is mounted horizontally, below the leadscrew.<br />
* Grit from grinding, sanding etc. forms a grinding paste with the way oil, and will rapidly wear out the ways, saddle and slides. Keep grit off at all costs e.g. by covering the ways and slides during grinding/sanding operations, and if there's any chance grit has gotten where it shouldn't, clean and re-lubricate *BEFORE* moving the carriage or slides, then move the carriage and slides, wipe down where they were with a clean paper towel and check there's no remaining traces of dirt other than clean way oil on the paper towel. If it doesn't come clean when you re-lubricate and move it again, a full strip down may be required to solvent clean and relubricate the precision sliding surfaces.<br />
* Although a metalworking lathe *can* be used to turn hardwood, wood dust and small chips are extremely pernicious, as they get everywhere, even clinging to clean surfaces, are abrasive due to their silica content, and are hygroscopic, promoting rust. An even more thorough clean-up than after using abrasives is needed, immediately afterwards. Oily wood dust and fine wood chips in significant quantities are a fire hazard, even in the trash bin.<br />
<br />
===Lubrication===<br />
See section: "Lubrication" in LittleMachineShop.com "Mini Lathe User’s Guide" [[Ian_M's_Lathe_Notes#Manuals|(below)]]. As we usually only open two nights a week, in the table on page 16, Daily lubrication becomes Weekly and Weekly becomes Monthly.<br />
<br />
===General Maintenance===<br />
* The grubscrews holding the cross-slide and compound slide dials tend to loosen due to vibration and use of the dials. Keep them snugged up, but not so tight the dials cant be set without an Allen key.<br />
<br />
* The screws holding the cross-slide nut tend to work loose due to vibration. Crank the handle to and fro through the backlash and visually check there is no movement of the screw heads in their holes. If there is, see the [[#Excessive_cross-slide_backlash|notes below]].<br />
<br />
===Removing the Carriage===<br />
Its possible to remove the carriage from the bed for cleaning etc. without dismantling it. The only stop to its motion is the righthand leadscrew bearing.<br />
<br />
Start by removing the tailstock. Crank the carriage to the tailstock end then remove the leadscrew bearing (two screws and a nyloc nut on the leadscrew end). With the half-nuts open, hold the leadscrew centered in them and crank the carriage off the end of its rack, then slide it off the end of the bed.<br />
<br />
Refitting is the reverse of removal, except (if its gibs are correctly adjusted) the carriage will be very tight on the end of the bed ways so may be difficult to work onto the ways without a stack of blocks of wood or similar to support it at exactly the right height. The righthand leadscrew bearing must be refitted with the carriage as close as possible to it and the half-nuts firmly closed to support the leadscrew at the correct height to hold it in alignment while the screws are being tightened. The nyloc nut controls leadscrew end-play. Fully tighten it then back it off slightly till the leadscrew turns freely with its change gear removed.<br />
<br />
If the Apron has been off, refit it with the screws no more than lightly finger tight and only finally tighten them after checking lead screw engagement at both ends of the carriage travel and that the rack and pinion operates smoothly over the full travel.<br />
<br />
== Issues and Annoyances ==<br />
As of September 2023 - mostly resolved, apart from the spindle bearings and runout, the lathe is in better condition than it has been for a number of years.<br />
<br />
===Four Jaw Chuck has two jaws too tight===<br />
Fixed 27/10/2023: The grooves in the opposite sides of the jaws that run in the chuck slots were slightly out of true, and the rails either side of the slots were slightly too thick towards the center. Due to the difficulty of seeing the high spots, after cleaning up and deburring the jaws didn't do enough to ease them, I decided to grind the top of the rails where they were binding. Several repetitions of spotting, grinding then diamond filing the high spots has eased them enough. I cleaned everything, greased the jaw slides and screws, and refitted the studs so the chuck is now fit for service. <s>Two of the chuck jaws are tight in their slots, making precise adjustment difficult due to lack of 'feel'. Moving the jaws round the slots shows the problem follows the jaw not the slot, and stoning various edges hasn't helped so it seems that the affected jaws are slightly oversize. Need Engineer's spotting blue to determine which of the sliding surfaces is binding, so we can see what needs scraping/stoning/grinding to fix them</s><br />
<br />
''N.B. Don't move the jaws to a different slot - the formerly tight jaws *must* stay in the slots furthest from the makers mark.''<br />
<br />
===Excessive Runout===<br />
Mostly fixed 24/10/2022: I ground the chuck seating surface of the spindle nose (outside lip) to under half a thou runout. This also cleaned up several burrs. It would be possible to do better, but that would need good spindle bearings, and a more rigid toolpost grinder mount.<br />
<br />
Our spindle nose was damaged years ago by a person with little mechanical aptitude (who shall remain nameless) beating it up with a hammer mushrooming the spindle nose. We are getting several thousandths runout at the end of the MT3 bore, a MT3 to MT2 reducer sleeve in it runs visibly out of true, as does the spindle nose flange. When you put a chuck on it, the runout is magnified by the distance from the spindle nose. Ideally we would replace the spindle when we change the bearings but its £52 [https://www.amadeal.co.uk/acatalog/4-Spindle-Upgrade-Real-Bull-Mini-lathe-CJ18-series-AMA_SP_CJ18_003RB.html#SID=9 from Amadeal] and money is tight. It may well require more work after the bearing upgrade. Once good bearings are in, if we can borrow a decent MT3 arbour as a reference, we should consider skimming the bore.<br />
<br />
===Spindle bearings===<br />
* The spindle bearings appear to be close to worn out. They are notably noisy when running, and there appears to be more slop in the spindle than is desirable. We have some ideas for possible replacement/upgrade, but it requires a major teardown.<br />
<br />
: The original bearings are allegedly 6206-2RS or 6206-ZZ deep groove ball bearings - 2RS codes rubber seals both sides and ZZ codes metal shields. Although the deep groove gives reasonable ability to withstand axial loads, the bearing balls point contact means they are vulnerable to [https://en.wikipedia.org/wiki/Brinelling brinelling] due to shock loading. The jammed on three jaw chuck didn't help this, as before we skimmed the spindle nose lip, it had to be driven off using a bar through the spindle bore, shock loading the bearings every time. Also even a minor 'crash' could have brinelled them due to eccentric shock loading, and the lathe has previously been crashed badly enough to need drive gear replacement. There are also issues with the 'approved' method of spindle and bearing removal from the headstock brinelling them, even if you don't abuse the spindle nose with a hammer!<br />
<br />
: A possible replacement is 30206 tapered roller bearings. The new bearings are slightly thicker so the plastic spindle spacer (15) needs to be machined to length to get the 45 tooth spur gear that drives the change gears laterally aligned with the tumbler gears. If a temporary replacement (3D printed?) is fitted, the lathe can be run (without power feed capability) so this can be done on the lathe after fitting the new bearings. As tapered roller bearings have line contact, they are significantly more resistant to brinelling.<br />
<br />
: ''See [[Talk:Ian_M%27s_Lathe_Notes]] for notes, links etc. for this upgrade.''<br />
<br />
===Motor stuttering===<br />
* Fixed 21/09/2023: The motor was running very erratically and it was very difficult to set a speed. Several loose connections were found in the control box, mostly loose female spades to the motor controller board, but also a dry jointed braking resistor on the 'Filter' board, and an inhibit wire completely off its terminal on the forward/reverse switch, making intermittent contact. After tightening and/or remaking all affected connections, it was much improved but still not right below 300 RPM. The remaining issues were due to poor wiper contact in the speed control pot, and stripping it, cleaning the track and contact ring and re-tensioning the contacts resulted in the motor now running smoothly over the full speed range. The speed is slow to settle, and while part of that is probably the lag in the digital tach, I suspect that the KBIC motor speed controller isn't properly tuned as it was (allegedly) previously replaced.<br />
<br />
===Drive belt slipping===<br />
* Fixed 28/9/2022: During testing the motor after the above issue, it was noted that the chuck could be stalled, slipping the drive belt, with not much torque. The drive belt was determined to be loose and a bit worn, but still in acceptable condition. <br />
<br />
: Access for servicing the belt requires removing the control box ''(2 spades to ZVR switch disconnect the supply, speed sensor and motor simply unplug from the 'filter board')'', the motor cover, chuck guard switch assembly + wiring cover, the change gear 'A' (drive) shaft carrier assembly, and the tumbler gear assembly. See https://youtu.be/EkxlIz01BdA for disassembly/reassembly, though on our lathe, the speed encoder ring on the spindle prevents the belt cover from being fully removed without disturbing the spindle nuts. There is enough room to work with it loose, but still trapped by the encoder ring. Also, unlike the video, if the 'jack' screws under the headstock are correctly adjusted, and the studs aren't excessively bent, there is no need to make custom studs. <br />
<br />
: It turns out that our lathe was missing the M6 hex headed jack screws that press the motor down to resist the belt tension, and the motor had cocked out of position at a severe angle. I know Ian B had had considerable trouble adjusting it after the motor fault back in October 2022, and I believe it had been getting slowly worse ever since. The jack screws were probably mistaken for headstock fixing bolts during disassembly after the crash that resulted in the metal Hi/Lo gears being fitted, then lost. The penny washers on the studs had dished, so I turned them over and backed them up with smaller washers and switched to nyloc nuts so they cant back off due to vibration. N.B. there is a packing washer on the motor side on one of the studs, presumably so the shaft is true to the ways. Adjusting the motor is awkward to say the least. One has to slack the stud nuts off a lot, pry under its rear end to lift it enough to be parallel to the ways, snug the stud nuts, check alignment, then set the jack screws and their lock nuts to hold it there, and finally tighten the stud nuts. <br />
<br />
: Tension: According to Sieg, it should be possible to twist the belt 90° mid span with a light finger grip. Other sources say 1/32" - 3/32" deflection mid span with light finger pressure.<br />
<br />
===Speed display blanking===<br />
* The speed display has been intermittent, blanking and flashing 8888 and 0 at certain speeds for as long as I have been using the lathe. Finally on 18/07/2022 it failed completely, with no display. I removed the display module and bench tested it - the pins are labelled 5V GND PL PE, PE is frame ground and PL is a TTL level pulse from the speed sensor - confirming that it was in good working order. My suspicions then turned to its power supply on the 'Filter' board. With both the sensor and display unplugged, the 5V rail was found to have a only a couple of volts, but the unreg DC was 17V and stable. Replacing the 78L05 5V regulator restored the 5V rail and normal operation.<br />
<br />
: ''I conclude its been failing for a while with high load current due to speeds with more lit segments causing it to drop out, resetting the speed display, causing it to blank, lowering the current enough for the regulator to recover, then the display MCU lamp tests (8888) then re-acquires the speed, repeating ad-nauseum till the speed is changed. I don't like the design as the high input voltage results in excessive dissipation.'' <br />
<br />
: ''ToDo: Bench test display to measure its worst case current consumption, then fit an appropriate dropper resistor to reduce the 78L05 dissipation.''<br />
<br />
===Quill spinning when drilling===<br />
* The quill was tending to spin while drilling because its anti-rotation pin (a M5 dog tip setscrew) was sheered. I've removed the debris, aligned the scale with the top of the tailstock and fitted a longer M5 dog-tip setscrew to replace it, with a nut to lock it at the correct height. N.B. the pin isn't that 'meaty' so if using big drills in tough metals, to prevent shearing it, it should be backed out so the quill can be turned by hand and unwanted rotation controlled by being quick with the quill lock if it starts to spin, or even using a close fitting rod in one of the chuck key holes with plastic tube over it to protect the ways. <br />
: ''If the screw sheers again, the quill will need to be removed and the tailstock taken off the lathe so the sheered tip can be shaken out, and if the setscrew is difficult to remove it probably means the threads are mangled where it sheered. Try driving it right through with the quill out.''<br />
<br />
===Sloppy quick change toolpost locking mechanism===<br />
* Once the dovetail clamp screw was slackened, there was nothing preventing the dovetail twisting or cocking significantly, and friction with the toolholder made it tend to do so, making toolholder insertion and removal more difficult unless the clamping screw was backed off excessively. I added a compression spring around the clamp screw inside the toolpost to push the dovetail outwards so it mostly retains alignment when open, allowing toolholders to slide on or off cleanly with far less screw slackening.<br />
<br />
===Leadscrew rubbing===<br />
* The leadscrew shaft is rubbing on the insulating separator inside the control box. Unfortunately the corner of the relay on the Filter Control Board (#160) doesn't allow enough clearance. Although the friction isn't much of a problem at high reduction ratios, e.g. 16:1 power feed, it increases the stress on the change gear train, and may be problematic when threading at feeds above 1:1. ''Possibly pack out the control box mountings by a couple of mm.'' <br />
<br />
===High/Low lever backwards!===<br />
* The high-low drive gear selector behind the headstock is incorrectly labelled and differs from the manual: low gear (which we normally use) is with the lever towards the tailstock. ''I suspect that the gears in the headstock were refitted the wrong way round when it was upgraded to metal gears.''<br />
<br />
: ''ToDo: Get it reassembled the right way round during the spindle bearing upgrade!''<br />
<br />
===Carriage lock fouls top slide===<br />
* The T handscrew has been replaced with a M5 hex headed bolt, to permit access when the top slide is over it. An 1/4" drive 8mm socket is usually left on it, but needs to be removed when the full cross slide travel is needed. The small (4 jaw) chuck key is near enough 1/4" to use for it. If you need to (un)lock it while the compound is over it, you'll need an 8mm spanner. ''The [https://www.amadeal.co.uk/acatalog/Mini-Lathe-Carriage-Lock-463.html Amadeal lock screw] is in the spares tin as it was too high and fouled the compound slide.''<br />
<br />
===Tailstock locking lever loose===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock - See full image for key to screws]]<br />
* Diagnosed and fixed 10/1/2023 - In the base of the upper section of the tailstock, there are two dog tip set screws that engage with locating grooves in the counter-rotating shafts carrying the eccentric locking cams. They'd backed off, probably due to vibration. They need to be tightened till they bottom out in the groove, making sure they are '''in''' the groove, backed off half a turn so the shafts can turn easily, and locked in place. There's no facility to do so, so reassemble with weak threadlocker. Unfortunately to get to them you have to remove the tailstock base slide, which is held on by the pressure of four adjusting grub screws, which all need backing off, and one socket headed bolt from underneath so full tailstock realignment is required after reassembly, which even for a rough alignment is tedious.<br />
: <s>The tailstock locking lever is loose and can be pulled out on its axis. It works OK when fully pushed home but needs investigating. ''I tightened the grub screw as the lever was coming off its shaft, but the whole shaft pushes/pulls in and out. It works OK fully pushed in, but it seems something that is meant to retain it has failed inside the tailstock base.</s><br />
<br />
===Gear alignment issues===<br />
* Change gear alignment is poor. I've currently got a gapped washer (to clear the key) packing out the A shaft so the gears line up, but this reduces the key's engagement so is problematic due to the high loading if the gears are set up for coarser threads. <s>Also I need to turn down some penny washers to slightly less than the root diameter of the metal 20T pinions, as gear retaining washers.</s> ''The gear retaining washers for A gear and B-C stub shaft are now done, turned down to slightly under 16 mm dia. Spares in the change gear tin. ToDo: The D (leadscrew) washer requires a larger center hole, so make two more with that hole.'' <br />
<br />
===Saddle gibs loose===<br />
* Fixed 11/04/2023: I took the apron off for access (and to clean the carriage handwheel gears), and found the front sheer plate screws were completely loose. I've snugged them up some and set the opposing grub screws and got a lot of the slop out. I've re-checked the front ones, and taken up the slop in the rear ones - Unfortunately it wasn't possible to get carriage movement to have an even 'feel' over its whole travel, and its noticeably tighter near the tailstock. If light hand pressure on the side of the unlocked carriage can cause movement (with the half-nuts open), its time to readjust them again, though it should be possible to move the carriage with a firm push. <s>The saddle gibs (actually the sheer plates) were too loose, to the point that engaging a slightly stiff threading dial could cause it to self-feed, an obvious crash hazard if working near the chuck or a step in the work.</s><br />
<br />
''N.B. the lefthand front opposing grubscrew is short, (fully recessed) and unlike the others does *NOT* have a locking nut as it must clear the traverse pinion. A wrap of PTFE tape provides enough friction to keep it in place, though possibly a bit of nylon fishing line down its hole would be better.''<br />
<br />
===Excessive cross-slide backlash===<br />
* ''Mostly Fixed <s>11/10/2022</s> again 07/11/2023:'' The cross-slide screw had excessive backlash (nearly three turns), possibly due to end float, which increases the risk of loosing track of the cut depth during threading operations. If you ended up off by a turn too far in, a crash was the most likely outcome.* 02/11/2023: The backlash is back up to one turn. I suspect the cross-slide screw nut mountings are working loose again.<br />
<br />
: So it turned out that the reason the cross-slide had nearly 3mm of backlash wasn't end float, it was loose cross-slide screw nut mountings. The nut has two socket headed cap screws pulling up, one either end, accessible from the top of the cross-slide, which control the tilt of the nut to take up backlash in the nut, and an opposing grub screw pressing down on the center of the nut to make it longitudinally rigid. I gambled the cap screws weren't too far out and snugged up the grub screw, and that immediately took out over 95% of the backlash which is now down to 10 divisions or so, or 0.25 mm. Shimming the cross-slide screw collar should take out some of what's left and careful adjustment of the nut tilt should get that down to under 0.1mm.<br />
<br />
: 07/11/2023: When the problem recurred I investigated further . It is difficult to get the cross-slide nut aligned correctly as it must be at the same height as the screw which is constrained by the bearing surfaces in the bracket. With the cross-slide almost at the front limit of its travel, I removed the screw and set the nut as level as possible and visually centered in the bore, then re-fitted the bracket and screw, then adjusted the tilt till it turned freely through the backlash. I then tilted it up at the front till some drag was felt to minimise the backlash and tightened the screws to lock it in place balancing them to maintain the same feel as I tightened them. The result was 7 divisions of backlash, acceptable but not great. During normal turning operations, the load on the nut is tension on the front screw and pressure on the grubscrew, so if it slackens again due to vibration from chatter, odds are it will be the rear screw that's loosened.<br />
<br />
: 16/11/2023: The backlash had crept back up to 11 divisions (0.275 mm). We don't have any >14 mm brass stock (or even near that) so I tried making the shim washer out of aluminium. I was shooting for 0.24 mm but due to poor technique got 0.28 mm. No good - locked solid. I lapped it down and tried it till I got it down to 0.20 mm which gave about 3 divisions backlash - good enough. However the cross-slide is now too tight. Maybe its pinching the edge, maybe a screw alignment issue or maybe there's a burr on the gib. A strip down will tell. <br />
<br />
* Further reduction of backlash: https://youtu.be/Wu_tI29JL2Y?t=163 <br />
: Brass tinned with Pb-free solder to form a white metal bearing surface should work at least as well as the bronze used in the video. The shim washer needs to be slightly over 10 mm ID and ~14 mm OD. It isn't necessary to remove the lead screw from the cross slide, as the washer can be fitted in-situ with only the bracket removed. Its also possible to closely estimate the required washer thickness from the backlash - note the number of dial divisions of backlash, then strip down the dial and bracket and with the gibs tight enough to keep the cross-slide from moving, push and pull the screw to assess its end float. A dial indicator mounted on the cross slide probing the screw flange will give you the total end float. Subtract the end float from the backlash, than take off another thou (0.025 mm) for running clearance to get the washer thickness (assuming it seats fully in the recess). If after fitting it, snugging up the bracket screws makes the screw too stiff to turn, the washer is too thick - either make another one or try to lap it down.<br />
: TLDR: measure flange on cross-slide screw and depth of recess in cross-slide bracket (behind dial) and machine a shim washer to take up nearly all the difference.<br />
<br />
===3 Jaw chuck didn't mount properly===<br />
* Fixed 7/4/2023 by grinding the spindle nose lip. The three jaw chuck can now be installed and removed by hand with no hammering. A test bar in it now has only 2 thou runout (TIR) at the chuck.<br />
: <s>The three jaw chuck and the faceplate aren't seating properly on the spindle nose. Its too tight on the register diameter of the lip. This results in grossly excessive runout, and also makes this chuck and the faceplate a PITA to fit or remove.</s><br />
: ''The spindle nose had been abused with a hammer (before my time) which mushroomed it and may have brinelled its bearings. See '''Excessive Runout''' and '''Spindle bearings''' above.''<br />
<br />
== Manuals, Books and other resources ==<br />
=== Manuals ===<br />
The [https://wiki.richmondmakerlabs.uk/images/a/a3/Lathe_InductionNotes.pdf RML CJ18A Mini-Lathe Induction Notes]. Your mandatory Lathe Induction will cover most of this but its good to be able to refer back to it.<br />
<br />
Official [https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Amadeal CJ18A Manual], or paper copy (less complete) kept on shelf above lathe.<br />
<br />
The [https://www.chesterhobbystore.com/wp-content/uploads/2022/11/Conquest-Super-Lathe.pdf Conquest Super Lathe manual] is considerably better than the Amadeal manual and is for a near-identical machine.<br />
<br />
The [https://littlemachineshop.com/images/gallery/info/minilatheusersguide.pdf Mini Lathe User’s Guide] from LittleMachineShop.com is even more comprehensive, going into its usage in some detail, with a proper TOC, and covers both US and Metric versions of Realbull Mini-lathes. ''The only fly in the ointment is the threading section assumes a US lead screw so change gear selections and threading dial divisions will not be correct for our lathe.''<br />
<br />
[https://www.arceurotrade.co.uk/machineguides/C3-Mini-Lathe-Dismantling-and-Reassembly-Guide.pdf Sieg C3 Mini-lathe Dismantling and Reassembly Guide] "A picture story book to help you dismantle and reassemble your Sieg C3 Mini-Lathe" ''It is similar enough to ours to serve as a maintenance guide, except for the electronics, spindle drive and other headstock innards.<br />
<br />
The motor controller is a clone of a [https://acim.nidec.com/drives/kbelectronics/-/media/kbelectronics/documents/dc-drives/manuals/kbic_manual.ashx?la=en KBIC® SCR DC Motor Speed Control]<br />
<br />
=== Books ===<br />
'''Metal Turning on the Lathe''', by David A Clark, Crowood Metalworking Guides, ISBN-13: 978-1847975232 [https://www.amazon.co.uk/gp/product/B00E78RKIG Kindle Edition (£8.99)]. ''A 'free' epub can be googled for, *NOT* linked here due to dubious legality.''<br />
<br />
'''[https://archive.org/details/03screwcuttinginthelathe Screwcutting In The Lathe]''', by Martin Cleeve (a pen-name of Kenneth C Hart), Workshop Practice series #3, ISBN-13: 9780852428382<br />
<br />
'''[https://archive.org/details/15workholdinginthelathe Workholding in the Lathe]''', by 'Tubal Cain' (a pen-name of Tom Walsh), Workshop Practice series #15, Argus Books, ISBN-10: 0852429088<br />
<br />
'''[https://archive.org/details/20metalworkandmachininghintsandtips Metalwork and Machining Hints and Tips]''', by Ian Bradley, Workshop Practice series #20, ISBN-13: 9780852429471<br />
<br />
'''[https://archive.org/details/38toolandcuttersharpening Tool and Cutter Sharpening]''', by Harold Hall, Workshop Practice series #38, ISBN-13: 9781854862419<br />
<br />
'''[https://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpaperT204.pdf Cutting Fluids]''', by EC Bingham, NIST Tech. Paper No. 204, 1921<br />
<br />
=== WWW resources ===<br />
==== Mini-lathe Specific ====<br />
There's a *LOT* of mini-lathe info online. Notable sites include:<br />
* http://www.mini-lathe.com/ - A major Realbull/Sieg mini-lathe resource.<br />
* http://mikesworkshop.weebly.com/lathe-modifications.html - many mods including carriage DRO autostop, and variable speed leadscrew motor drive, cross-slide motor drive, etc. He also has a page with a bunch of accessories, toolholders etc. - http://mikesworkshop.weebly.com/lathe-accessories-and-tooling.html<br />
* http://andysmachines.weebly.com/variable-speed-controls.html - Scroll down to the 'UPDATE' section for the schematic of a very similar SCR speed control board. It also has the schematic for an earlier version of the Auxiliary Control Board (aka: 'Filter' board).<br />
<br />
==== Forums ====<br />
''with publicly accessible archives''<br />
* https://groups.io/g/7x12MiniLathe - Mini-lathe specific, active<br />
* https://www.hobby-machinist.com/forums/mini-lathe-mini-mill-information.220/ - active<br />
==== Youtube Playlists & Videos ====<br />
* Blondihacks: [https://www.youtube.com/playlist?list=PLY67-4BrEae9Ad91LPRIhcLJM9fO-HJyN Lathe Skills] (playlist) - "This is an educational series to help you learn to use your metal lathe. Watch them in order for best results! Satisfaction not guaranteed, especially if you're a cranky sort of person."<br />
* Frank Hoose (Minilathe.com) has a couple of relevant Youtube playlists:<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn7ON0jGM5UbM-KZDT56MOIp Mini Lathe Operations]<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn4nGRZaVq3wTOlvZNOmdAZ2 Mini Lathe Overview]<br />
<br />
==== General Machining ====<br />
* https://www.machiningdoctor.com/ - "THE #1 MACHINING TECHNICAL HUB"<br />
<br />
==Projects==<br />
[[File:VESA mount.jpg|thumb|Machined VESA mounting plate (left) and plate from Dell monitor stand it must match (right). The translucent washer shows the size of the original center hole.]]<br />
* My first faceplate project was boring out the center hole in a VESA mounting plate to adapt it to fit onto a surplus Dell 1708FP monitor stand. The part was centered using the tailstock dead center engaging with its original center hole. I clamped the part with studs and penny washers on the driving side of two opposite corners, with cap screws in the next slot round to trap the corners under the clamping washers, then withdrew the tailstock and dead center. After machining out the bore, I used the tip of the tool, rotating the chuck by hand, to scribe a circle for laying out the bolt holes. I finished off laying out and drilling the bolt and locating holes by hand at home, fitted it to the stand, and mounted the 2nd hand LG 24" widescreen monitor.<br />
<br />
* Another ultimately unsuccessful project was fly cutting aluminum flat bar to thickness to make custom shims for the set of carbide insert tools, for the four way toolpost. The 8 mm shank tools need ~2.5 mm shim stacks, and the 6 mm shank tools need ~4.5 mm shim stacks. Ideally I'd machine single shims, but the only stock I've got handy cleans up to only 3.2mm, and some fine shimming may be needed to fine-tune the tool height.<br />
<br />
: After sorting out the clamps so they were no longer twisting the aluminum flat bar stock, and switching to the short 45° turning SCMT06204 insert tool in the four way toolpost, to improve rigidity and get a well controlled tip radius, the finish was much improved. I'm still having problems getting an even thickness and am getting approx. 0.05mm variation, I suspect due to the aluminium bar stock distorting due to internal stresses as its surface is cut away. ''ToDo: try supergluing the stock to the faceplate before clamping to further reduce chatter and stop the warping.''<br />
: Looking back on this project a year later, its fairly obvious that the thickness variation was probably due to faceplate surface runout due to the damaged spindle nose.<br />
<br />
* Raphael has been working on a steel rocket nozzle with some assistance from myself. We have set up the rough cut chunk of ~ 50mm steel bar, faced both ends (to 50mm length) and turned the OD to 49mm to clean it up. Its going to need through drilling, probably some boring, and quite a bit of detail work on the OD. It will then need to be transferred to a jig in the drill press vice to allow a pattern of angled traverse holes to be drilled with acceptable accuracy.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=File:CJ18A_Cutting_Speeds.pdf&diff=17587File:CJ18A Cutting Speeds.pdf2023-11-16T12:20:16Z<p>IanM: Max. RPM for various materials on our CJ18A minilathe. Computed by Ian.M. Source data from LittleMachineShop.com</p>
<hr />
<div>== Summary ==<br />
Max. RPM for various materials on our CJ18A minilathe. Computed by Ian.M. Source data from LittleMachineShop.com</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_Lathe_Notes&diff=17586Ian M's Lathe Notes2023-11-15T00:58:05Z<p>IanM: /* Shimming */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br />
<br />
''Currently these notes are semi-organized and non-authoritative. As I become more experienced with the RML CJ18A mini-lathe, I'm cleaning up, extending and reorganising them. Some lathe operating experience is assumed. If in doubt, '''*ASK*''' me, Andy H<sup>*</sup> , Jonathan H or another experienced minilathe operator!<br />
<br />
''* Andy H should be asked (for an authoritative answer) any questions involving RML usage policies or acquiring tooling or materials through RML.''<br />
<br />
== The Lathe ==<br />
Our Facilities page [[Facilities#Lathe|has]]:<br />
<blockquote><br />
'''Lathe'''<br />
[[File: Lathe2.jpg |200px|right | Lathe]]<br />
In the kitchen. <br />
<br />
Marked as a CJ18A Mini-Lathe from [[https://www.amadeal.co.uk/acatalog/CJ18A-Mini-Lathe-7x14-Machine-100mm-3jaw-Metric-With-Metal-Gears-AMA_LA_CJ18_M_3_MGRB.html Amadeal]]<br />
[[https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Manual]] <br />
<br />
[[Media:Lathe InductionNotes.pdf| Induction Document]]<br />
<br />
Possible upgrades:<br />
*https://www.youtube.com/watch?v=GwT-JQLbNPA<br />
<br />
''Please do not use the lathe until you have received induction'' <br />
<br clear=all><br />
</blockquote><br />
Its a Chinese import 7x14 mini-lathe. The 7x14 refers to the maximum diameter and length of work, in inches and is only a theoretical measure of the working envelope as you loose length to the chuck + any tailstock tooling, and the diameter is over the bed, not the cross-slide. See actual specifications below. <br />
<br />
Most if not all Chinese 7x10 to 7x16 mini-lathes seem to be remarkably similar (not uncommon with Chinese products due to [https://www.bunniestudios.com/blog/?p=284 Shanzhai (山寨)] )<br />
and the OEM of our Amadeal CJ18A Mini-Lathe was probably [https://www.made-in-china.com/showroom/cheap-lathe Yangzhou Realbull Machinery Co. Ltd]. Very similar lathes are also made by [https://www.siegind.com/lathe-machine.html Sieg], but their lathes tend to be slightly less sophisticated than the equivalent Realbull models.<br />
<br />
''N.B. Many Sieg parts are known to have slight but critical differences from Realbull parts, so '''DON'T''' order Sieg spares for a Realbull lathe!<br />
<br />
== Key Specifications ==<br />
Amadeal says the CJ18A Mini-Lathe is a 7x14 model with:<br />
<blockquote><br />
* Power 550 W<br />
* Distance between centres : 350 mm<br />
* Swing Over Bed: 180 mm<br />
* Swing Over Cross Slide: 110 mm<br />
* Taper: MT3<br />
* Tailstock Taper: MT2<br />
* Chuck diameter: 100 mm<br />
* Spindle Speed: 50 - 2500 rpm ''(with digital readout)''<br />
* Spindle Bore: 20 mm<br />
* Cross slide Travel: 65 mm<br />
* Range of Metric Threads: 0.5 - 2.5mm.<br />
</blockquote><br />
* The lead screw is metric, pitch 1.5 mm.<br />
* The spindle center is 90.6 mm above the flat of the bed (measured).<br />
<br />
Even though the compound and cross slide handwheels appear to be calibrated in thousandths of an inch, as ours is a metric machine, they only approximate that. One turn of a slide handwheel is 1mm advance, and they have 40 divisions, so each division is 0.025 mm, (approx. 0.984 [https://en.wikipedia.org/wiki/Thousandth_of_an_inch thou]). Similarly, the tailstock quill advances 1.25 mm per handwheel turn, which has 50 division dial, giving the same 0.025 mm divisions, but only 4 turns per 5 mm. The carriage handwheel is awkward - it moves approx. 19.2 mm per turn, and doesn't have a dial scale.<br />
<br />
== Notable Accessories ==<br />
We have:<br />
* [https://www.amadeal.co.uk/acatalog/160mm-Face-Plate-for-the-4-Mini-lathe-AMA_AC_CJ18A_FP160RB.html#SID=129 160 mm (6 1/4") Faceplate]<br />
* 100 mm (4") three jaw self-centering chuck (OEM standard) 22.5mm bore, with inside and outside jaw sets<br />
* 100 mm (4") four jaw (independent) chuck with reversible jaws (8 TPI screws)<br />
* Tailstock drill chuck (max. 13 mm dia.)<br />
* Live center for tailstock (+ OEM fixed center) <br />
* Four way Tool Post (OEM Standard)<br />
* [https://www.amadeal.co.uk/acatalog/Quick_Change_Tool_Post_for_the_mini-lathe.html Quick Change Tool Post] + 3 tool holders<br />
* [https://www.amadeal.co.uk/acatalog/Fixed-Steady-for-Mini-Lathes-AMA_AC_CJ18A_FSRB.html#SID=145 Fixed Steady Rest]<br />
* [https://www.amadeal.co.uk/acatalog/Travelling-Rest-for-Mini-Lathes-AMA_AC_CJ18_TSRB.html#SID=144 Travelling Steady Rest]<br />
<br />
''You'll find all of the above on the shelf above the lathe, with the accessories in the wooden box, apart from the steadies, which live next to it. Change gears, spare parts, and most cutting tool tips/blanks are in labelled white rectangular tins behind the lathe.''<br />
=== Measuring Tools ===<br />
We have:<br />
* Various dial indicators - the one with the adjustable magnetic base stand is the most convenient for most lathe setup work.<br />
* 25mm micrometer (in little grey case)<br />
* Grey case containing set of measurement tools including dial calipers, micrometer, steel rule (metric & inch), engineers square, and a fish-tail gauge<br />
<br />
''We currently lack''<br />
* ''A tool height setting gauge''<br />
<br />
=== Hand Tools ===<br />
Some common tools needed for normal use are kept with the lathe, in or attached to the wooden accessories box:<br />
* 2 mm Allen key - adjusting cross-slide and compound gibs<br />
* 4 mm Allen key - quick change toolholder tool clamping screws + height adjust, tightening dials<br />
* 5 mm Allen key - four way toolpost tool clamping screws, engaging/disengaging threading indicator<br />
* 6 mm Allen key - locking/unlocking quick change toolholder<br />
* 8 mm spanner - locking carriage when 8 mm socket can't be used, locking gib adjuster nuts <br />
* 13 mm spanner - changing chucks, locking steady rest jaws<br />
* Very long needle nose pliers - for grabbing swarf safely, holding one end of emery cloth safely so you can keep your fingers away from the jaws, and extricating small objects from awkward places.<br />
<br />
== Change Gears ==<br />
[[File:BC puller 1.jpg|thumb|Custom puller for B-C stub shaft]] [[File:BC puller 2.jpg|thumb|Pulling the B-C stub shaft]]<br />
See "Conquest Super Lathe" manual ([[#Manuals|below]]), section '''4.7 Change Gears''', PDF pages 28-29, but see below for mesh adjustment. The LittleMachineShop.com "Mini Lathe User’s Guide" (also below) section '''Threading''' gives a far better explanation, with pictures and diagrams, but its for a lathe with a US 1/16 inch pitch leadscrew, not a metric 1.5 mm pitch one like ours, so you *MUST* ignore all the tables in that section, replacing them with metric mini-lathe (with 1.5 mm pitch leadscrew) equivalents. <br />
<br />
We have the following tooth count gears: 20,20, 30, 35, 40,40, 45, 50,50, 60,60, 80,80<br />
which consist of the OEM power feed gears + the metric change gear set. Apart from the metal 20 tooth pinions, they are all plastic, probably Delrin if the molded in 'POM' marking can be trusted, but possibly plain Nylon 6, and are metric Module 1.<br />
<br />
If we wanted to add the capability to cut US/Imperial threads we'd need to buy additional 55, 57 and 65 tooth gears, and possibly a 21 tooth metal pinion.<br />
<br />
CGTK's [https://www.cgtk.co.uk/metalwork/calculators/changegears/minilathe?gears1=20,20,30,35,40,40,45&gears2=50,50,60,60,80,80&gears3= Change Gear Calculator] ''(link preloaded with our gear list)'' is useful if you don't want to calculate the ratios from first principles. Not all suggested combos will physically fit.<br />
<br />
* Take care *NOT* to loose the keys in the A and D shaft keyways - turn each shaft till the keyway is up before removing the gear. <br />
* The B and C gears are coupled by a hollow stub shaft (with an integral key), which is so tight in the gears it has to be pressed or driven out - I've made a puller just for this task, kept in the change gears tin.<br />
* The center of the B-C stub shaft *MUST* be lubricated where it runs on its pin on the change gear banjo bracket, with grease or heavy oil. ''Seizure of the stub shaft due to running dry is a frequent cause of catastrophic mini-lathe geartrain failures!''<br />
* Don't get oil on the change gears as it can cause plastic gears to crack. Only PTFE drylube or plastic compatible white grease should be used on their teeth. <br />
* Adjust the B-C pin position in the straight slot first to set the C to D gear mesh, tighten its nut, then swing the whole banjo about the D shaft boss to set the A to B mesh, and finally tighten the banjo clamping nut.<br />
* Check both gear meshes have running clearance by turning the chuck by hand enough to complete one full turn of the leadscrew, and by attempting to turn the intermediate gear(s) to assess backlash, If excessive resistance is felt or if there's significant backlash, readjust the gears. If you have difficulty judging the mesh, a strip of 80 gsm copier paper (approx. 0.1 mm thick) wound into the meshing teeth before tightening the stud or banjo will give appropriate clearance once removed. Once setup, check the gears run quietly under power.<br />
* If the sum of the tooth counts C+D is the same as for the ones you just removed and they were correctly meshed, you don't need to move the stub shaft pin. If A+B is <u>also</u> the same, you don't need to move the banjo. e.g. If it was set up for 16:1 reduction power feed, 1 mm (40:60 - 50:50) for M6 and 1.5 mm (e.g. 40:60:40) for M10 pitches can thus be achieved by only swapping gears. <br />
<br />
''The change gears, puller, etc. and a box spanner for the banjo nut are kept in a white rectangular tin behind the lathe.''<br />
<br />
=== Power Feed ===<br />
When used for turning with power feed, the change gears should be set for a 16:1 reduction (A:20 : B:80 - C:20 : D:80) using the pair of small metal 20 tooth pinions and the 80 tooth plastic gears (largest in set), for a feed of 0.09375 mm per turn (1.5 mm/16). Unless continuing your threading project the next session, please re-fit the 16:1 power feed set after threading so the power feed is ready for use. <br />
<br />
* *ALWAYS* leave the feed direction selector lever in its neutral (no feed) position, and the half-nuts open after use.<br />
* *ALWAYS* check the carriage lock is disengaged before engaging power feed. Unlock the carriage after use. <br />
<br />
=== Threading Dial ===<br />
The threading dial is an aid to re-engaging the half-nuts at the right moment so the tool will retrace its previous path cutting deeper, rather than offsetting axially some fraction of the thread pitch and ruining your work. Its based on the concept of the lowest integer multiples of the leadscrew and thread ''(being cut)'' pitches that exactly match, but for mechanical simplicity it only covers certain selected multiples of the leadscrew pitch.<br />
<br />
We have a choice of three pinion gears:<br />
{| class=wikitable<br />
|+ Threading dial Pinion Gears<br />
|-<br />
! Teeth !! Colour Dot !! Usable lines !! OD gear !! Dist. per turn<br />
|-<br />
| 14 || Red || 1,7 || 7.51 mm || 21 mm<br />
|-<br />
| 15 || Orange || 1,5,9 || 8.05 mm || 22.5 mm<br />
|-<br />
| 16 || Green || 1,4,7,10 || 8.37 mm || 24 mm (2 mm/div)<br />
|}<br />
They are now colour coded, with a paint dot on the gear end face ''(the only non-wear surface)''. The 16 tooth one is normally left on the lathe, but disengaged when not threading to minimise wear on the lead screw. The others are kept in the Change Gear tin.<br />
<br />
There's a threading dial 'pickup' calculator here: https://www.cgtk.co.uk/metalwork/calculators/threaddialindicator <br />
<br />
Initially select ''Lathe:'' '''Custom''', and enter the following below:<br />
* ''Units:'' '''Metric'''<br />
* ''Lead Screw Pitch (mm):'' '''1.5'''<br />
* ''Thread Dial Indicator Gear Teeth:'' '''16,15,14''' <br />
* ''Lines on Thread Dial Indicator:'' '''12''' <br />
* ''Line Marking:'' '''Every Line Numbered'''<br />
Note the teeth list is entered in reverse order so the resulting table highlights any required pinion changes.<br />
<br />
N.B. The dial is only friction clamped to the pinion by its center screw. If you have any reason to suspect it may not be properly aligned: <br />
# With the power off and the carriage unlocked, engage the feed direction lever upwards. You'll probably need to turn the chuck by hand to get it to engage.<br />
# If the threading indicator isn't already engaged, loosen the threading dial support block bolt, pivot the block to engage the pinion with the leadscrew and retighten the bolt.<br />
# Engage the half nuts, again turning the chuck by hand till they drop in. <br />
# Turn the chuck a couple of turns, top towards you to take up any backlash, then lock the carriage, taking care not to push it left while locking it.<br />
# Loosen the screw securing the dial to the pinion.<br />
# Align the '1' line of the dial with the index line, by rotating the dial clockwise, then retighten the screw.<br />
# Don't forget to disengage half-nuts and unlock the carriage!<br />
<br />
The above instructions should result in the half-nuts engaging cleanly when exactly on any valid line when threading towards the headstock. If it is required to thread away from the headstock, there will be a slight offset from the line due to backlash between the spindle gear and leadscrew, so engage slightly early.<br />
<br />
Changing the pinion:<br />
# Loosen the threading dial support block bolt and disengage from the leadscrew.<br />
# Undo dial center screw, and remove it and the dial, dropping the old pinion out the bottom.<br />
# Oil the shaft of the new pinion with a drop of light oil and insert it from below, gear end down.<br />
# Refit dial and screw.<br />
# Check the dial and pinion turn freely with minimal resistance.<br />
# Align as above.<br />
<br />
== Tailstock and Steadies ==<br />
These are mostly used to support long work ''(long with respect to its diameter)'' to improve rigidity, increasing accuracy and reducing chatter. The Tailstock quill is also used with a drill chuck for drilling.<br />
=== Tailstock ===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock base]]<br />
The tailstock can be offset to turn shallow tapers between centers. We don't currently have the accessories to turn between centers, namely <s>a MT3 dead center for the spindle, or</s> any drive dogs for the work. Also realigning the tailstock after turning a taper can be a PITA. The photo shows the tailstock adjusting screw locations ''(C - Lateral, and D - Skew)'' and the block on the baseplate they engage with. Adjustments can only take effect when the tailstock locking lever is eased to take the pressure off the baseplate. As we don't have a MT3 center, one has to turn a fresh point on a test workpiece for a rough tailstock alignment reference. Fine alignment, to avoid inadvertent taper turning, can be done by mounting a long precision ground bar between the chuck (or preferably a center in the spindle), and a dead center in the tailstock and sweeping it with a dial indicator on the carriage. Finally a test cut should be taken at either end of a bar between centers, and the diameters checked with a micrometer. Assuming the bed has previously been properly levelled and shimmed to take out twist ''(not the case at RML as we don't have it bolted down)'', any remaining difference in diameter will be double the tailstock offset, smaller at the tailstock being offset towards the front. Fine adjustment cant be achieved by jacking with the screws, its best to ease the adjusting screws, bump the tailstock into alignment then take up the screws again, checking the alignment is maintained when the tailstock is unlocked and relocked. There is no vertical adjustment, though shims can be added between the tailstock and its base.<br />
<br />
==== Tailstock Quill ====<br />
There is a metric/imperial scale on the top of the quill, read against the end of the tailstock, for depth measurement when drilling. The tailstock quill has a 1.25 mm pitch thread and a 50 division dial. Each division is therefore 0.025 mm, and it only takes 4 full turns of the handwheel to move the quill 5 mm. <br />
<br />
To eject MT2 taper tooling and centers from the tailstock, wind the quill all the way in.<br />
<br />
N.B. The quill anti-rotation pin (dog-tip setscrew + locking nut in top of tailstock near to the quill lock) is only M5. It will sheer if a large diameter drill jams in the work. Please back it out clear of its keyway if using large drills, and use alternative methods of preventing chuck rotation. To re-engage it, crank the quill out till you can see the keyway, align it with the screw and screw in the screw till it gently bottoms out, then back it off a quarter turn. Try twisting the quill to check its properly engaged, then tighten the locking nut gently to hold the screw in position clear of the bottom of the keyway.<br />
<br />
=== Steady Rests ===<br />
We have two, both with brass tips that must be kept lubricated during use.<br />
<br />
The fixed steady mounts on the ways, and is most useful when turning longer work that wont fit through the spindle bore. Adjustment is critical, and the surface the tips run on must be smooth and concentric, as any misalignment that forces the work off center will result in the work wobbling in the chuck, marring it, with a high risk of it becoming un-chucked, which can be dangerous at speed.<br />
<br />
The travelling steady mounts to the headstock side of the carriage to locally resist the deflection of thin long work, due to the cutting forces. It only has two tips, to resist climb, and deflection away from the tool, and requires readjustment after every cutting pass.<br />
<br />
== Tooling and Tool Holders ==<br />
'''Key dimensional data:'''<br />
* The quick change holders accept up to 10 mm shank tools. <br />
* The four way toolpost has 50 mm long sides, a seat width of 15 mm and can clamp tools of up to 5/8" (15.875 mm) shank ''(check this)'', but the slot base is only 10.4 mm below the spindle center so cannot be used with >10 mm shank tooling unless it has a dropped tip. Large tooling with a centered tip is also problematic as you run out of height above the shank when trying to shim to match the spindle center height. <br />
<br />
===Quick Change Toolpost===<br />
I've got the quick change toolpost and toolholders setup for mostly easy use. The three toolholders came with cantilever height setting arms which historically haven't been installed as the supplied fixing screws were too short. That's all now sorted out and a HSS RH turning tool and a HSS hand-ground grooving/parting-off tool are now mounted in two of the holders and set to height. The third is kept free for other tools. <br />
<br />
The quick change toolpost has been modified with a spring to press the dovetail clamp outwards and help stop it twisting or flopping about to ease toolholder fitting and removal. The dovetail clamp (socket headed screw on toolpost side opposite dovetail) feels a bit stiffer than before, but will take less than half a turn to go from open (with the toolholder lifting out or dropping in easily) to fully clamped. As there is so much less clearance in the open position you should no longer need to wiggle the toolholder while clamping it to get a consistent height. If the dovetail clamp ever gets misaligned, twist it straight by eye, slacken off a bit further than usual to get a toolholder on, clamp it to align the dovetail then release, reseat the toolholder and re-clamp to ensure its at its preset height. You cant adjust the height by 'jacking' with the height screw due to its offset leverage. Instead, back off the height screw and hold the toolholder at the desired height while locking the dovetail clamp, then adjust the height screw (and locking nut) to hold it there, then check it doesnt change height significantly when you unclamp and reclamp the dovetail. <br />
<br />
Unfortunately the OEM height setting screws foul the toolpost locking nut handle. Currently, if you need to swap toolposts you will have to first remove the quick-change tool holder from the post. There is enough nut handle swing to allow the quick change toolpost to be unclamped and rotated to fine set the tool angle without removing the toolholder. It also seems the mating surfaces may be slightly out of square, as if you rotate the toolpost 90° or 180°, the nut swing may be insufficient to re-clamp it without removing the toolholder to do so. Add a M10 washer under the locking nut if the handle ends up pointing in an undesirable direction! A thin M10 washer is kept with the toolpost collar for this purpose, and will shift the handle position by about a third of a turn. <br />
<br />
''ToDo: Make a taller nut of a similar pattern, to clear the height setting screws.''<br />
<br />
===Four Way Toolpost===<br />
The OEM four way toolpost is significantly more rigid than the quick change toolpost + holders because it has fewer and thicker parts and less overhang. Therefore the four way toolpost should be used when using carbide tooling. It requires shimming under the tool to set the tip height to the spindle center height - see below. The tool shanks are mostly significantly less than 15 mm wide, so need to be centered under its clamping screws, tempting as it is push the shank in for full side contact with the toolpost. If possible clamp the shank with all three screws not just two.<br />
<br />
==== Shimming ====<br />
We typically only mount up to two tools, and want maximum rigidity, so use 50 mm x 15 mm shims, (the full seat area), preferably with deburred edges and radiused corners so they aren't a hazard to the operator.<br />
<br />
We have pre-cut and marked shims of the following thicknesses: <br />
* 1x 3.23 mm, 2.42 mm, 1.56 mm, 0.32 mm, and 0.25 mm<br />
* 2x 1.00 mm, 0.77 mm, 0.12 mm, 0.11 mm, 0.10 mm and 0.05 mm<br />
* 4x 0.53 mm<br />
<br />
Our shims are mostly found materials (hence the awkward thicknesses) and are mostly a mixture of aluminium and steel, with a couple of GRP ones. The toolpost seat '''<u>must be absolutely clean</u>''' to avoid embedding debris in the aluminium or GRP shims, to get a consistent height and avoid tilting the tool - wipe it every time you change a tool! Put the thin shims at the bottom of the stack to avoid the tool shank edges creasing them. Shims are kept in a little yellow plastic box with a clear lid, near the carbide tools case.<br />
<br />
I made a tool height setting gauge (T shaped black acrylic with steps in its sides) which can be used to check the tool tip height matches the spindle center height using either the flat of the ways or the saddle as a reference. The tool tip should just fit under the lip of the appropriate step, with the T arms across the ways flats or on the saddle. It is kept in the box with the carbide insert tools.<br />
<br />
''ToDo:'' <br />
<br />
* ''Cut more shims neatly, mark them with their thickness.''<br />
* <s>''Do test cuts and start noting shim stack-ups for various tools.''</s><br />
* ''Organise shim storage!''<br />
<br />
=== HSS Tools ===<br />
[[File:Tool Bit Geometry.jpeg|thumb|Single point cutting tool geometry]]<br />
Our HSS tools are made from 8 mm square bar stock, hand-ground to tip profile in-house. See LittleMachineShop's [https://littlemachineshop.com/images/gallery/instructions/grindingtoolbits.pdf Grinding Tool Bits] notes. <br />
<br />
I've installed our usual HSS LH turning and parting off tools in two of the quick change holders and set the heights correctly. There are a couple of other HSS tools or tool blanks knocking about. Taking heavy cuts turning steel (even with good cutting oil) blunts HSS tools fairly quickly, which are time-consuming to re-sharpen nicely without a dedicated tool & cutter grinder with appropriate jigs. Its worth noting that the usual 'speeds & feeds' tables are commonly based on surface speeds expected to give a half hour (active cutting) tool life before resharpening.<br />
<br />
I touched up the LH turning tool by lapping on wet & dry (silicon carbide) paper on glass (Aka: [https://en.wikipedia.org/wiki/Scary_sharp 'Scary Sharp']) working upwards through the grits 200, 400, 600 and finally 1000, initially 'bluing' the surfaces to be lapped with a marker pen to see which areas needed taking down more. The end of the tool was significantly uneven so I touched that up freehand on the bench grinder to flatten it when it became apparent that 200 grit lapping wasn't cutting where it needed to. There was an existing micro-bevel on the leading side, which I kept. Finally I 'dubbed' the leading corner vertical edge on the 1000 grit to give it a very slight nose radius. A test cut on brass gave a very nice finish when turning.<br />
<br />
''Ian B has purchased some spare 8mm HSS tool blanks - talk to a lathe trainer if your proposed lathe work needs custom ground HSS tooling.'''<br />
<br />
=== Brazed Tungsten Carbide Tools ===<br />
Somewhat of a half-way house between hand ground HSS tooling and insert tooling with the disadvantages of both and some more besides - e.g. they are much harder to sharpen. So why do we bother? Some tool geometries would be awkward and tedious to hand grind, and Chinese import brazed carbide tooling is about half the price of similar HSS tooling, and far more readily available. Also, for space constrained tooling like boring bars, if you want carbide, for insert tooling, the size of the insert and its clamping seriously limits the minimum hole diameter you can work in. I have purchased a set of 3/8" shank brazed carbide tipped boring bars, but we currently cant sharpen them, due to lack of a diamond grinding wheel. <br />
<br />
=== Tungsten Carbide Insert Tools===<br />
Decoding ISO insert tooling part numbers: https://www.cutwel.co.uk/blog/learn-the-turning-tool-iso-code-system<br />
[[File:Carbide set.jpg|800px|thumb|left|Our set of Tungsten carbide insert lathe tools (before the new inserts were fitted)]]<br />
<br />
{| class=wikitable<br />
|+ Tools, left to right, (+ last across top):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| SSKCR0610H06 || 75° through boring || SCMT06204 || Long || 6 || 6.34 || ''4.33''<br />
|-<br />
| SSSCR0610H06 || 45° deep facing, internal chamfering || SCMT06204 || Long || 6 || 6.13 || ''4.58''<br />
|-<br />
| SWUCR0610H05 || 93° boring, deep facing || WCMT050308 || Long || 6 || 6.22 || ''4.48''<br />
|-<br />
| SWGCR0810E05 || 90° RH turning & facing || WCMT050308 || Short || 8 || 8.25 || '''2.45'''<br />
|-<br />
| SSSCR0610E06 || 45° turning, chamfering || SCMT06204 || Short || 8 || 8.75 || ''1.93''<br />
|-<br />
| SSBCR0610E06 || 75° RH turning, chamfering || SCMT06204 || Short || 8 || 8.72 || ''1.98''<br />
|-<br />
| LW0810R-04 || 60° external threading || JCL15-120 || Short || 8 || 7.44 * || ''3.28''<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || 8.23 || ''2.5 ?''<br />
|-<br />
| LN0813R-04 || 60° internal threading || JCL15-120 || Long || 7.95 || 7.44 * || ''3.28''<br />
|}<br />
<br />
{| class=wikitable<br />
|+ More Tools, (loose in tin):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || ~8.5 (not in use) ||<br />
|-<br />
| [https://www.glanze.co.uk/product/glanze-12-mm-60-degree-metric-internal-threading-tool/ Glanse SIR0012K11] || 60° internal threading bar || 11IRA60 || Long || 12 dia || ??? || ???<br />
|}<br />
''Shim stack heights in bold are tested, in italic are only calculated.'' ''Tip heights marked * are with new JCL15-120I inserts. The single remaining plain JCL15-120 insert has a slightly higher tip height.''<br />
<br />
Carbide tooling typically requires two to three times more speed than HSS and at least a couple of 'thou' depth of cut for best results.<br />
<br />
Chatter can rapidly kill carbide tooling by chipping the cutting edge. To improve rigidity and reduce the risk of chatter, the cross-slide and compound gib screws need to be well adjusted so there is minimal play in the slides, tool stick-out should be minimised, the four way toolpost should be kept over the cross-slide, and the work should be kept close to the chuck (or otherwise supported by tailstock or steady rest) to avoid excessive deflection.<br />
<br />
Thermal shock is almost instant death to carbide, and when dry cutting the insert tip can run very hot, so do not add extra cutting fluid manually during the cut. Pre-apply what you need, evenly, before starting the cut.<br />
<br />
Parting off or facing to center is high risk - if the tool tip is even slightly below center or if tool or work deflection takes it below center, the work will tend to climb over the tool tip as the cut approaches center, breaking the insert. To avoid this, the tool should be shimmed slightly above center, sufficient to allow for work and tool deflection, and unless very close to the chuck, a steady should be used. Its often preferable to part to a couple of mm dia. remaining then stop and saw through the remainder. Parting off hollow parts is much lower risk.<br />
<br />
Further investigation of the Tungsten carbide insert tool height situation is not encouraging - the so-called 'set' in question does not have a consistent tip height ''(see above table)''! In a real set, the insert seats *should* be machined allowing for the insert thickness to bring all the cutting edges to the same height with respect to the shank underside. However if you place them tip to tip on a table its easy to see there is considerable height variation, so they need to be individually shimmed (or at best, one machined shim will only be right for two or three tools). At this time we don't have dedicated shim stacks for each tool.<br />
<br />
A 2.42 mm thick shim brings the SWGCR0810E05 90° RH turning & facing tool almost exactly to center height, and good results were obtained turning 1" steel pipe. However facing 50mm steel bar stock to center found it to be slightly low, leaving a fractionally under 0.05 mm 'pip' so it needs another 0.03 mm to bring it fractionally above center. Fractionally too high is generally preferable to fractionally too low, due to tool deflection, so adding an 0.05 mm shim to the stack should produce optimum results.<br />
<br />
==== Inserts ====<br />
Ian B has purchased the spare inserts we needed in sets of five. He even was able to get the CK3 parting-off inserts which had been difficult to source!<br />
<br />
Inserts used in above tool set:<br />
* 3x SCMT06204 (square, indexable) https://www.rdgtools.co.uk/acatalog/SCMT-06-Carbide-Insert.html<br />
* 2x WCMT050308 (triangular, indexable) https://www.rdgtools.co.uk/acatalog/WCMT-05-T3-08-5XTIP-8813.html<br />
* 2x JCL15-120 (60 deg threading point) https://www.rdgtools.co.uk/acatalog/X5-JCL-15-120L-THREADING-TIPS-60-DEGREE--X5-TIP---23455.html<br />
* CK3 (parting off) https://www.rdgtools.co.uk/acatalog/CK3-CARBIDE-TIPS---PARTING--BOX-OF-5PCS--9437.html<br />
<br />
Inserts used in other tools:<br />
* 1x CK3 (as above) also missing from spare parting off tool<br />
* 1x 11IRA60 in Glanse threading bar + 1x spare<br />
<br />
=== Drills ===<br />
Various sizes of center drills are kept in a plastic bag next to the wooden accessories tray. There's also a small box of 2.5 mm center drills.<br />
<br />
We have a set of 11 TiN coated HSS drill bits from 1.5 to 8 mm, (in a cylindrical plastic index box) for tailstock drilling of brass, aluminium and non-abrasive plastics. To keep them sharp enough for the precision work we expect from the lathe, please don't use them for steel or reinforced plastics, and don't borrow them for non-lathe use. Metric and US [https://littlemachineshop.com/reference/numberdrillsize.php numbered]/[https://littlemachineshop.com/reference/letterdrillsize.php lettered] general use HSS drill bits are kept in two red metal index boxes next to the drill press.<br />
<br />
== Using the Lathe ==<br />
=== General ===<br />
A cutting speed chart for HSS tooling, published by Model Engineer magazine can be found [https://www.model-engineer.co.uk/sites/7/documents/cutting%20speed%20chart.pdf [here<nowiki>]</nowiki>]. The second row is the target feed rate and the rest of the chart, apart from the diameter column is RPM.<br />
<br />
For carbide tooling cutting iron and steels, recommended speeds are generally three times higher than for HSS, but the CJ18A 2500 RPM max. spindle speed (in high gear) means you can only reach the optimum speed range for over 15 mm dia work. For small diameter work, HSS tooling may well be a better choice.<br />
<br />
An online metric speeds calculator is here: https://www.cgtk.co.uk/metalwork/calculators/cuttingspeeds <br />
<br />
How to do the maths to calculate speeds and feeds: https://www.cutwel.co.uk/blog/speeds-feeds-made-easy<br />
<br />
Making dimensioned parts is primarily done by touching off the tool tip on a reference surface (with the lathe stopped, turning the chuck by hand), zeroing the handwheel dial, then manually counting turns and divisions. When backing off the tool its best to do so by exactly one whole turn so you don't forget the previous dial position. Stopping and measuring the work before taking the final cuts is essential if high accuracy is required. ''I've changed out the dial setscrews for flat tip ones with a tiny slug of solder under them so the dials are now friction fit on their shafts. i.e. if you hold the handle firmly taking up the backlash in the direction of cut, you can zero the dial just by grabbing and twisting it.''<br />
<br />
Carriage movement is less easy to measure as the handwheel is uncalibrated and advances an awkward bit over 19.2 mm per turn. Your options here when shoulders or other features must be exactly positioned are, in order of increasing accuracy: <br />
* Use measuring instruments, scribe the work at the desired length then work to the scribed line. Its often convenient to black the work with a permanent marker, then scribe with the tool tip, turning the chuck by hand.<br />
* for short distances, lock the carriage and use the compound, set parallel to the work<br />
* Set up a long travel dial indicator to measure carriage motion. <br />
N.B. with the leadscrew stopped, and the threading dial engaged, with its default 16 tooth gear, it will make one turn for every 24 mm of carriage movement (2 mm/div). This isn't accurate enough for positioning but is sufficient to check you aren't out by a whole mm or more.<br />
<br />
Do not allow any solvents to contact the chuck guard clear plastic as it will make the plastic brittle, or even craze it, and try to avoid melting it with the work light!<br />
<br />
=== Slide Locks ===<br />
* The carriage can be locked to the ways using the M5 hex screw through the top of the saddle to the left of the cross-slide. Double check the leadscrew is disengaged and the half-nuts open before locking it. Lock it when facing.<br />
* The cross slide can be locked by a M4 socket headed cap screw just in front of its middle gib screw. Locking the cross slide is helpful when turning very shallow conical features where the cross slide handle is in the way of the compound.<br />
* The compound slide can be locked by a M4 socket headed cap screw in line with the edge of the toolpost mount on the side with the gib adjustment screws. In normal use it should be kept backed off half a turn but it is desirable to tighten it for parting off operations to keep the resulting end faces flat.<br />
<br />
=== Chucks and Chuck Jaws ===<br />
==== Terminology ====<br />
* Inside jaws have steps on the outside to grip the ID of hollow work, but can also be used as outside jaws on small diameter parts (i.e. that fit through the spindle). <br />
* Outside jaws have steps on the inside to grip the OD of the work.<br />
* Universal chucks have a scroll plate with a spiral screw thread that moves all the jaws.<br />
* Independent chucks have individual adjusting screws for each jaw.<br />
<br />
==== The Chucks ====<br />
* The three jaw universal chuck can only grip near round or hexagonal work, which it centers, but its concentricity is not perfect so e.g. if you reverse the work and continue turning at the same diameter from the other end, you will see a line where the turned surfaces meet. It has separate sets of inside and outside jaws, and we normally keep the inside set installed to use as outside jaws for small diameter work.<br />
<br />
** Our jaws are individually numbered, stamped in the groove. They must be fitted in the correct sequence. The jaw slots are not clearly marked. Lowest runout for small dia. parts is achieved if you fit the jaws with #1 anticlockwise of the makers mark, then continue anticlockwise for #2 and #3.<br />
** A large strong rubber band is a great help getting all the jaws started on the scroll together - with slots #1 and #3 above the centerline and the scroll thread outer tip between #1 and #3, insert jaws #1 and #2 and put the rubber band round them to keep them in their slots. Insert jaw #3 and stretch the rubber band over it to hold it up into its slot. If the scroll was positioned correctly, all jaws should be at the same initial radius. The jaws can now be cranked in with the chuck key and they should all engage in step so they meet in the middle.<br />
:: ''Mini-lathe.com have the best instructions for [https://www.mini-lathe.com/mini_lathe/chucks/chucks.htm#Installing_Chuck_Jaws changing the jaws].'' <br />
<br />
* The four independent jaw chuck can grip most roundish or squarish work, which can either be carefully centered by the user, or deliberately gripped off-center. <br />
** Its jaws are reversible so can be swapped from inside to outside by simply cranking each jaw out and reinserting it the other way round, one at a time. DON'T move the jaws to different slots as they are likely to bind.<br />
** When setting up to face the sides of rectangular objects held crossways, it may be helpful to use both inside and outside jaw orientations, in symmetrical opposing pairs.<br />
** Its screws move their jaw 1/8" (3.125 mm) per turn<br />
<br />
* The jaws must '''never''' protrude from the chuck OD by more than one step, and for safety, its preferable they don't protrude at all, as they make the gap between the front of the bed and the chuck body an even more unforgiving meat grinder, and as the number of teeth engaged with the scroll or screw decreases, they loose strength, just when you need it the most to grip larger/heavier work. <br />
<br />
''Neither chuck is well suited to gripping tapered work safely. When seating work that doesn't quite fit through the chuck bore (which is larger than the 20mm spindle bore limit), be careful that it isn't seating on the chamfered edge of the chuck bore as it is far to easy to get the work slightly cocked so it doesn't run true.''<br />
<br />
==== Changing Chucks ====<br />
* When changing chucks, use the small grey plastic mat to protect the ways under the jaws in case you drop the chuck.<br />
* The spindle nose has two patterns of holes - the three hole pattern is for the three jaw chuck and the faceplate, and the four hole pattern is for the four jaw chuck. One hole is shared between the patterns, and is marked on the spindle nose.<br />
* To fit a chuck:<br />
** First check that the spindle nose and chuck back and recess are free of swarf, grit or other debris. Any foreign objects will tilt the chuck causing excessive runout and may mar the surfaces.<br />
** Remove the nuts and split lock washers from its studs, line its studs up with the hole pattern (preferably with the stud nearest anticlockwise to the makers mark through the marked spindle hole), fit and hold it in place with your right hand, and with your left, get the lock washer and nut on the top stud, and take up the slack.<br />
** One one nut is on, you no longer have to worry about dropping it, and can work round fitting the remaining washers and nuts, taking up the slack on each as you fit it. <br />
** Next, work round again getting them all finger tight, then tighten them gently, and finally work round fully tightening them. <br />
* Removal is the reverse of refitting. Put the washers and nuts back on the chuck's studs so they don't get lost.<br />
<br />
=== Faceplate Work ===<br />
Faceplate work is probably the most dangerous operation you can (or rather should) perform on a lathe. The working area is a large diameter spinning surface with protruding clamps to fixture the part that it is impractical to guard. Protruding clamps, studs, nuts etc. are very difficult to see at speed.<br />
<br />
'''Treat the faceplate with great respect and caution if you wish to continue to be able to count to ten on your fingers!''' <br />
<br />
The 65 mm cross-slide travel vs the 80 mm faceplate radius is a serious limitation that may require creative compound, toolpost and tool setups for larger parts, and doing full face cuts in two sections.<br />
<br />
''It is common practice to skim the faceplate to ensure it runs true. We have not (yet) done this, and wont till the spindle is in better bearings and the nose reground to minimise runout.''<br />
<br />
==== Clamping ====<br />
Open ended/sided clamps should be oriented so that cutting forces drive the work towards the clamping bolt/stud, not out from under the clamp. Minimize the protruding length of thread past the clamping nut, if necessary using sacrificial bolts or studs you can cut to length, or even using a long M8 stud for one of the faceplate mountings, so you can get a clamp nearer to the faceplate center. Double-check all clamps are secure, manually turn the faceplate to check the work and clamps clear the ways, top-slide and toolpost, and stand out of the 'line of fire' (a disc extending from the faceplate) when spinning up the work for the first time. <br />
<br />
If you need to machine close to a clamp, consider marking a safe limit circle on the faceplate and work with a marker pen to make it easier to see how close the cutting tool is to crash disaster. <br />
<br />
I strongly advise reading chapter two of Tubal Cain's book "Workholding in the Lathe" several times before your first faceplate setup, and if possible get another experienced lathe user to check your first few setups before spinning them up.<br />
<br />
==== Chuck Guard Removal ====<br />
The faceplate is too large diameter to fit under the chuck guard, but the guard has an interlock switch wqhich must be closed for the lathe to run. The guard is now fitted with wing nuts so it can be removed allowing the the interlock switch to close when using the faceplate. It *SHOULD* *ALWAYS* be refitted if a chuck is fitted, except when turning work too large to clear the guard. <br />
<br />
''The chuck guard is primarily there to make it very difficult to start the lathe without removing the chuck key and to reduce the area of large diameter spinning surface exposed. It may slow down the projectile if a chuck sheds a jaw but is unlikely to stop it. Also it serves to contain coolant spray spun off the chuck. As we don't use flood coolant this usually isn't an issue for us. As setting up for faceplate work doesn't use a chuck key, and the most hazardous zone is the face of the faceplate, with its spinning projecting clamps, with full access required for machining operations, which a guard would not cover, the consensus is that removing the guard is an acceptable risk.''<br />
<br />
=== Turning and Facing ===<br />
We are getting good results in aluminium, brass, and even steel using HSS cutting tools in quick-change tool holders, and the ~ 94 um/turn power feed. Unfortunately due to lack of rigidity in both the machine and smaller diameter parts, if you don't want the outer end to be over diameter, a light final cut and multiple 'spring' passes will probably be required.<br />
<br />
For aluminium, a sharp HSS tool and 0.5 mm (20 div) depth of cut gives good results with power feed for rapid stock removal. Its also easy maths as each cut takes ~ 1 mm off the diameter. Finish cuts should be much finer, 0.1 mm (4 div) is 'in the ballpark'.<br />
<br />
For steel, using carbide insert tooling, a 0.25 mm (10 div) depth of cut is more appropriate, and with pre-applied cutting oil, gives reasonable results with power feed if you use enough speed. The maths is not quite so easy as you are only taking 0.5 mm off the diameter per pass. Again, use finer finish cuts but try to plan your cuts so the final cut is still cutting, not smearing the surface!<br />
<br />
When facing or parting off, some skill is required to turn the cross-slide handwheel steadily to get a decent finish and to avoid shock-loading the tool tip. Increasing the spindle speed in one or more steps to keep up with the reducing diameter is advisable, but avoid speeds that cause resonances (resulting in chatter). When parting off, small through-hole parts may be caught on a thin rod chucked in the tailstock, and pre-positioned inside the work with its tip right up to the parting off position.<br />
<br />
==== Using the Steady Rests ====<br />
For the fixed steady rest, see Blondihacks' Lathe Skills #26 - How To Use a Steady Rest! [[#Youtube_Playlists_&_Videos|{below}]]<br />
<br />
Ours doesn't have ball bearing fingers, so a smooth surface on the work and adequate lubrication are essential. The thumbscrews can only tighten the fingers, so for small adjustments outwards you need to either slack off the clamping nuts or ease them slightly and use a drift against the back of the finger's slot. Once set, check the chuck still turns freely.<br />
<br />
The traveling steady rest needs to run on a machined surface, so at least for the first pass, must follow the tool, so its difficult to avoid using more compound slide overhang than is desirable. An initial surface should be cut next to the chuck or tailstock center before fitting the steady rest.<br />
<br />
Both are a PITA to fit - the fixed one has to have its clamping post inserted up through the bed, and the supplied spanner is useless near the headstock, and the travelling one's mounting holes on the saddle almost invariably need swarf picked out of them.<br />
<br />
==== Turning Between Centers ====<br />
<s>Using a MT3 to MT2 reducing sleeve, the MT2 dead center can be fitted in the spindle.</s> ''Currently the MT3 spindle taper is compromised.'' Alternatively, a soft center can be turned immediately before use in the three jaw chuck, but that must have its 60° point re-cut to concentric if the chuck is disturbed, and needs to be either large enough to bear on the chuck body, or must have a lip to bear on the end face of the jaws to take the axial thrust. Recutting the center is a PITA, as the compound angle must be set to 30° anticlockwise, then reset to a true 0° afterwards. Maybe a right-hand 30° end angle zero rake form tool is the answer, or use the carbide insert tool SSKCR0610H06 as a form tool with the toolpost rotated 15° anticlockwise.<br />
<br />
With the MT2 live center in the tailstock quill, this gives us a center either end of the work to hold it.<br />
<br />
We also need a drive dog similar to [https://littlemachineshop.com/products/product_view.php?ProductID=4473&category=1 this], and the corresponding drive post to bolt to the spindle nose. I have some 25mm bore thick wall iron pipe, which should do nicely. Lengths of the dog's straight tail and of the post TBD after I check how much the center protrudes. N.B. its recommended to tie the tail to the post to keep them in contact so they don't slam. ''Currently we will need to drive from the chuck jaws. Possibly use the exterior jaws with a short soft center gripped on the inside end and drive from the highest step.''<br />
<br />
=== Drilling ===<br />
Always start with a center drill so deflection of longer bits doesn't start the hole off-center. For larger bits (> 5 mm), first drill to the web size, then to final diameter. For a precision hole, drill slightly undersize and ream to final diameter. ''Supply your own reamers!''<br />
<br />
Caution: See note about the quill anti-rotation pin in section [[#Tailstock Quill|Tailstock Quill]] above.<br />
<br />
=== Boring ===<br />
Caution: As the spindle doesn't extend right through the headstock housing, if boring in a through hole, chips tend to fall out the back and tumble in the spindle bore till they fall into the change gears. To avoid this, one should plug the spindle bore with a wad of paper towel or rag and when cleaning up afterwards, use a rod to push it through towards the tailstock, with the chuck jaws (if fitted) wound clear of the spindle bore.<br />
<br />
A swivel bladed hole deburring tool (pale blue handle) can be found in the main room on the windowsill behind the drill press.<br />
<br />
A couple of boring jobs have been bodged with an awkwardly angled turning tool and achieving acceptable effective rake with enough clearance to reach deep enough into the hole has been problematic. I reviewed the tools we had and found none suitable for starting out in a 13mm bore, the max diameter we can (easily) drill. I therefore decided to buy a set of boring bars and make a holder for them. I had difficulty finding anything affordable under 10mm shank - the best low cost option was a [https://www.amazon.co.uk/dp/B07P5LGVBX set of nine 3/8" (9.525 mm) shank brazed carbide tipped boring bars], which would be close to the max capacity of the quick change boring bar holder - if we had one! Unfortunately this holder for our specific toolpost is difficult to find except in a toolpost bundle. Another annoyance is the variable tip height of the set, varying from 1.8 mm to 2.8 mm above the center of the shank.<br />
<br />
I therefore decided to make a boring bar holder of the [https://littlemachineshop.com/products/product_view.php?ProductID=1700 Littlemachineshop.com (USA) style] for use in the four way toolpost, as the additional rigidity will certainly help. Starting with a slightly over 50 mm length of 16 mm aluminium square bar and using the four jaw chuck , both ends were faced and an attempt was made to find its center and center drill it. It was then drilled out to ~9.8 mm after much drama due to blunt drills and drills that cut ~1mm oversize. Too big, but beggars cant be choosers as we didn't have a boring bar holder or a 3/8" reamer. Unfortunately the final hole ended up significantly off center. It was then chucked crossways and ~1 mm skimmed off its thickest side to gain clearance to allow it to be shimmed to height, then one side was slit lengthwise manually with a hacksaw.<br />
<br />
It was fitted to the for way toolpost and loaded with a booring bar, which clamped firmly. A 0.86 mm shim stack brought the tip of the largest boring bar almost spot on center height, with the difference easily accommodated by twisting the tool slightly. The three jaw chuck was then remounted, and a piece of iron pipe chucked for a test. It cuts well and leaves a decent surface finish.<br />
<br />
''The boring bar setup is a work in progress - talk to me before attempting to use them if you have a project that would benefit from boring..''<br />
<br />
ToDo: get something that can sharpen tools tipped with this grade of carbide - it needs some sort of diamond (or possibly CBN) wheel as green grit silicon carbide does little more than polish it. ''N.B. diamond wheels are rapidly eroded by grinding steel, so the supporting steel seat must be undercut with a regular grinding wheel before the diamond wheel can contact it.'' <br />
<br />
We'll also need 50 mm square sheet shims to fit under the toolpost to gain clearance in the toolpost above the tool or toolholder. A 2.4 mm shim would give us about the same above and below spindle center height, and we probably need a small selection of thinner ones.<br />
<br />
=== Thread Cutting ===<br />
The objective is to cut a thread that complies with the ISO metric thread profile. Our lathe is not currently equipped to cut non-metric threads, (with the exception of BA which have pitches based on metric threads of that era).<br />
<br />
[[File:ISO and UTS Thread Dimensions.svg|frame|center|Metric Thread Profile - from the geometry, H is ~86.6% of P]]<br />
<br />
Metric thread data - See 'Preferred Sizes' at: https://en.wikipedia.org/wiki/ISO_metric_screw_thread<br />
<br />
See "Mini Lathe User’s Guide" section '''Threading''' for general techniques *ONLY*, and above for change gears and threading dial setup.<br />
<br />
Amadeal specify the max. thread pitch as 2.5 mm. Any thread pitch greater than 1.5 nn requires the change gears to gear up. When gearing up it is desirable to distribute the ratio as evenly as possible over the two pairs of gears in the geartrain to avoid excessive tooth loading.<br />
<br />
==== External Threading ====<br />
Initially turn work to required Major Diameter, set up change gears and threading tool, touch off on the work, zero the top and cross slide dials, and do a 'scratch' pass to check the pitch. Back off the tool, return the carriage, and re-engage the half nuts on a valid dial line clear of the end of the thread then immediately stop the lathe, and hand turn the chuck till the tool tip is (hopefully) over the scratch to check the thread pickup. If all is good, return the carriage again, restart the lathe and start cutting your thread. <br />
<br />
Methods of doing so vary depending on the size of the thread and toughness of the metal, but straight-in plunge cutting is generally to be avoided as has the highest cutting forces, and does not reliably keep the carriage (and top-slide if set parallel to the work) loaded to avoid pitch errors due to backlash. <br />
<br />
If leaving the half-nuts engaged and reversing the lathe to return to the start of the thread for the next pass, its absolutely essential to back the tool out of the thread for the return pass as it will not follow the path of the cutting pass due to backlash in the geartrain, leadscrew mounts and half-nuts.<br />
<br />
==== Internal Threading ====<br />
''<nothing here yet>''<br />
<br />
== Cutting fluids ==<br />
=== Why bother? ===<br />
[https://youtu.be/mRuSYQ5Npek Watch this video] and contemplate what's actually happening to that thin ribbon of metal being removed. Most of the lathe's motor power is being turned into heat by internal friction in the chip being removed in the zone around the cutting edge, and surface friction at, and immediately behind the cutting edge, near-instantly heating the chip by up to several hundred degrees. Reducing the surface friction using a suitable cutting oil reduces the strain on the machine as a whole, and reduces workpiece and tool heating (and thus expansion) with consequent improvements in maximum usable feed and depth of cut, surface finish and accuracy. It also drastically increases the life of the cutting edge.<br />
<br />
=== Practicalities === <br />
We don't have a coolant system for the lathe and *really* don't want the maintenance hassles of using soluble cutting oil/coolant as if used infrequently its a PITA to keep recirculated high water content cutting fluids from going rancid and stinky, and they can also rust the ways, so even a total loss gravity feed system is problematic. Therefore if dry machining doesn't give a good enough finish, we tend to use oil applied topically, by hand to the work. <br />
<br />
* Hard brass is typically free-turning without oil, however some light oil for the final cut can improve surface finish, but with the disadvantage that it will increase loose chip buildup on the tool as hard brass typically forms short spalls or splinters rather than curly chips.<br />
<br />
* Many Aluminium alloys tend to be gummy, and Paraffin or other mineral spirits mixed with a little oil can help prevent the aluminum welding to the tool edge. WD40 will do at a pinch, but its messy to apply from a spray can.<br />
<br />
* Steel really needs *GOOD* cutting oil. Lard oil is the traditional choice for steel. If there are any objections to lard oil, we should bite the bullet and get some commercial dark high Sulphur cutting oil, but beware, many such oils use an additive package that includes lard oil.<br />
* Cast iron (except ductile) should be cut dry, as the carbon micro-inclusions self-lubricate it, and the carbide in the dust (primarily Cementite) are very abrasive, so tend to form a grinding compound if mixed with oil. <br />
<br />
I've sorted out an oil pot lid with a 1/2" brass collar soldered in to give a nice smooth sided hole, for ease of use and to minimize the risk of spills when using a brush to apply cutting oils, and got some dirt-cheap brushes. It fits Shippam's paste (and similar own-brand spread) jars and I've found several jars and ordinary lids to seal them for storage. Unfortunately it isn't the easiest to get this type of jars' lids back on square so they seal properly, and if you over-tighten them and there's a temperature change, they can be a total <expletive> to reopen. Using the rubberised handles of a large pair of pliers to grip the jar lid just above its rim is the best option, and avoids damaging the lids.<br />
<br />
''N.B. For the smaller brushes, the glue holding the bristles in is attacked by paraffin. To prevent loss of bristles, crimp the aluminium ferrule of each new brush of this type before use.''<br />
<br />
We have, in labelled jars:<br />
<br />
* Sulphurised Lard oil thinned with paraffin. Best choice for heavy cuts and threading in steel but stinky.<br />
* Lard oil thinned with paraffin. Good for steel and acceptable for softer copper alloys<br />
* Paraffin with a trace of light oil. Good for aluminium, and can help prevent squealing chatter on finish cuts in brass.<br />
<br />
I've also got some paraffin wax (in the form of a stubby candle), which can be applied lightly (under power) to brass and aluminium stock especially on the finish pass. It makes less mess than oil but unfortunately tends to build up on the tool tip, making it difficult to 'work by eye' without frequent pauses to clean the tool tip.<br />
<br />
We've also got a tin of [https://www.rocol.com/products/rtd-compound Rocol RTD cutting compound], which is a thick paste. Its highly recommended for drilling and tapping steel (in the drill press or by hand), but as a paste, is less useful for general lathe work unless thinned to a fluid consistency, e.g. with paraffin or white spirits. OTOH its certainly worth trying for high speed facing steel as it is less likely to get flung off.<br />
<br />
== Cleaning and Maintenance ==<br />
Swarf is a significant cut hazard to the operator, especially stringy swarf from cutting steel. Never touch it bare-handed - always use a tool e.g. a brush, or a hook, or needle nose pliers for grabbing long swarf.<br />
<br />
* After use, brush all swarf off the toolholder, compound and cross slide etc. ways and leadscrew. Ian B has blocked off the opening at the headstock end of the rear splashguard (to try to keep swarf out of the motor), so one must sweep the swarf towards the open tailstock end and catch it in a dustpan or similar. Preferably, also thoroughly clean out the chip tray under the lathe, but at least sweep out visible swarf.<br />
* Wipe up any cutting fluid residue and re-lubricate affected sliding surfaces with way oil.<br />
* Do not solvent clean the chuck guard, as it will make the plastic brittle, or even craze it. Water with a little detergent is permissible for cleaning it, with the guard totally removed from the lathe.<br />
<br />
Before engaging the half-nuts for power feed/threading, check the leadscrew is clean! ''Best cleaned under power, with a toothbrush.'' <br />
<br />
'''Caution:''' The traverse gears behind the carriage handwheel are in an open-backed housing and tend to become packed with swarf! Swarf buildup here will result in jerky carriage movement. Clean out as much as you can with a toothbrush ...<br />
<br />
===Lack of lubrication and/or swarf or dirt build-up can be disastrous===<br />
* If using the change gears/power feed, lack of lubrication of the B-C stub shaft center pin or either leadscrew end bearing can result in seizure and immediate destruction of one or more gears in the gear train or worse. <br />
* Small pieces of swarf can get between the saddle and ways, or into the slides degrading accuracy, possibly permanently if hard swarf scores them, or jamming them. The carriage handwheel gears behind the apron are notorious for accumulating swarf, and swarf buildup on the leadscrew can prevent the half-nuts engaging properly, resulting in scrapped work, and possibly stripped half-nuts. <br />
* Metal swarf can get into the motor (''though Ian B has modified the rear chip catcher to reduce the risk)'' or into the control box via the leadscrew, and short-circuit stuff. At best it will blow the fuse and need a strip-down to clean it out, at worst it may require a replacement [https://www.amadeal.co.uk/acatalog/Speed-Control-Circuit-Board--12amp-AMA_SP_CJ18_SCB12.html#SID=12 speed controller] ''(currently £96)'' and/or [https://www.amadeal.co.uk/acatalog/550W-motor-for-CJ18A-Mini-Lathe-467.html#SID=240 motor] ''(currently £105)'' and possibly other electrical parts. We should probably fit a [https://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C3-Mini-Lathe-Spares/C3-256-Leadscrew-Grommet-Dustproof-Cover C3-256 Leadscrew Grommet] to keep swarf out of the control box, as it tends to drop onto the 'Filter' board which is mounted horizontally, below the leadscrew.<br />
* Grit from grinding, sanding etc. forms a grinding paste with the way oil, and will rapidly wear out the ways, saddle and slides. Keep grit off at all costs e.g. by covering the ways and slides during grinding/sanding operations, and if there's any chance grit has gotten where it shouldn't, clean and re-lubricate *BEFORE* moving the carriage or slides, then move the carriage and slides, wipe down where they were with a clean paper towel and check there's no remaining traces of dirt other than clean way oil on the paper towel. If it doesn't come clean when you re-lubricate and move it again, a full strip down may be required to solvent clean and relubricate the precision sliding surfaces.<br />
* Although a metalworking lathe *can* be used to turn hardwood, wood dust and small chips are extremely pernicious, as they get everywhere, even clinging to clean surfaces, are abrasive due to their silica content, and are hygroscopic, promoting rust. An even more thorough clean-up than after using abrasives is needed, immediately afterwards. Oily wood dust and fine wood chips in significant quantities are a fire hazard, even in the trash bin.<br />
<br />
===Lubrication===<br />
See section: "Lubrication" in LittleMachineShop.com "Mini Lathe User’s Guide" [[Ian_M's_Lathe_Notes#Manuals|(below)]]. As we usually only open two nights a week, in the table on page 16, Daily lubrication becomes Weekly and Weekly becomes Monthly.<br />
<br />
===General Maintenance===<br />
* The grubscrews holding the cross-slide and compound slide dials tend to loosen due to vibration and use of the dials. Keep them snugged up, but not so tight the dials cant be set without an Allen key.<br />
<br />
* The screws holding the cross-slide nut tend to work loose due to vibration. Crank the handle to and fro through the backlash and visually check there is no movement of the screw heads in their holes. If there is, see the [[#Excessive_cross-slide_backlash|notes below]].<br />
<br />
===Removing the Carriage===<br />
Its possible to remove the carriage from the bed for cleaning etc. without dismantling it. The only stop to its motion is the righthand leadscrew bearing.<br />
<br />
Start by removing the tailstock. Crank the carriage to the tailstock end then remove the leadscrew bearing (two screws and a nyloc nut on the leadscrew end). With the half-nuts open, hold the leadscrew centered in them and crank the carriage off the end of its rack, then slide it off the end of the bed.<br />
<br />
Refitting is the reverse of removal, except (if its gibs are correctly adjusted) the carriage will be very tight on the end of the bed ways so may be difficult to work onto the ways without a stack of blocks of wood or similar to support it at exactly the right height. The righthand leadscrew bearing must be refitted with the carriage as close as possible to it and the half-nuts firmly closed to support the leadscrew at the correct height to hold it in alignment while the screws are being tightened. The nyloc nut controls leadscrew end-play. Fully tighten it then back it off slightly till the leadscrew turns freely with its change gear removed.<br />
<br />
If the Apron has been off, refit it with the screws no more than lightly finger tight and only finally tighten them after checking lead screw engagement at both ends of the carriage travel and that the rack and pinion operates smoothly over the full travel.<br />
<br />
== Issues and Annoyances ==<br />
As of September 2023 - mostly resolved, apart from the spindle bearings and runout, the lathe is in better condition than it has been for a number of years.<br />
<br />
===Four Jaw Chuck has two jaws too tight===<br />
Fixed 27/10/2023: The grooves in the opposite sides of the jaws that run in the chuck slots were slightly out of true, and the rails either side of the slots were slightly too thick towards the center. Due to the difficulty of seeing the high spots, after cleaning up and deburring the jaws didn't do enough to ease them, I decided to grind the top of the rails where they were binding. Several repetitions of spotting, grinding then diamond filing the high spots has eased them enough. I cleaned everything, greased the jaw slides and screws, and refitted the studs so the chuck is now fit for service. <s>Two of the chuck jaws are tight in their slots, making precise adjustment difficult due to lack of 'feel'. Moving the jaws round the slots shows the problem follows the jaw not the slot, and stoning various edges hasn't helped so it seems that the affected jaws are slightly oversize. Need Engineer's spotting blue to determine which of the sliding surfaces is binding, so we can see what needs scraping/stoning/grinding to fix them</s><br />
<br />
''N.B. Don't move the jaws to a different slot - the formerly tight jaws *must* stay in the slots furthest from the makers mark.''<br />
<br />
===Excessive Runout===<br />
Mostly fixed 24/10/2022: I ground the chuck seating surface of the spindle nose (outside lip) to under half a thou runout. This also cleaned up several burrs. It would be possible to do better, but that would need good spindle bearings, and a more rigid toolpost grinder mount.<br />
<br />
Our spindle nose was damaged years ago by a person with little mechanical aptitude (who shall remain nameless) beating it up with a hammer mushrooming the spindle nose. We are getting several thousandths runout at the end of the MT3 bore, a MT3 to MT2 reducer sleeve in it runs visibly out of true, as does the spindle nose flange. When you put a chuck on it, the runout is magnified by the distance from the spindle nose. Ideally we would replace the spindle when we change the bearings but its £52 [https://www.amadeal.co.uk/acatalog/4-Spindle-Upgrade-Real-Bull-Mini-lathe-CJ18-series-AMA_SP_CJ18_003RB.html#SID=9 from Amadeal] and money is tight. It may well require more work after the bearing upgrade. Once good bearings are in, if we can borrow a decent MT3 arbour as a reference, we should consider skimming the bore.<br />
<br />
===Spindle bearings===<br />
* The spindle bearings appear to be close to worn out. They are notably noisy when running, and there appears to be more slop in the spindle than is desirable. We have some ideas for possible replacement/upgrade, but it requires a major teardown.<br />
<br />
: The original bearings are allegedly 6206-2RS or 6206-ZZ deep groove ball bearings - 2RS codes rubber seals both sides and ZZ codes metal shields. Although the deep groove gives reasonable ability to withstand axial loads, the bearing balls point contact means they are vulnerable to [https://en.wikipedia.org/wiki/Brinelling brinelling] due to shock loading. The jammed on three jaw chuck didn't help this, as before we skimmed the spindle nose lip, it had to be driven off using a bar through the spindle bore, shock loading the bearings every time. Also even a minor 'crash' could have brinelled them due to eccentric shock loading, and the lathe has previously been crashed badly enough to need drive gear replacement. There are also issues with the 'approved' method of spindle and bearing removal from the headstock brinelling them, even if you don't abuse the spindle nose with a hammer!<br />
<br />
: A possible replacement is 30206 tapered roller bearings. The new bearings are slightly thicker so the plastic spindle spacer (15) needs to be machined to length to get the 45 tooth spur gear that drives the change gears laterally aligned with the tumbler gears. If a temporary replacement (3D printed?) is fitted, the lathe can be run (without power feed capability) so this can be done on the lathe after fitting the new bearings. As tapered roller bearings have line contact, they are significantly more resistant to brinelling.<br />
<br />
: ''See [[Talk:Ian_M%27s_Lathe_Notes]] for notes, links etc. for this upgrade.''<br />
<br />
===Motor stuttering===<br />
* Fixed 21/09/2023: The motor was running very erratically and it was very difficult to set a speed. Several loose connections were found in the control box, mostly loose female spades to the motor controller board, but also a dry jointed braking resistor on the 'Filter' board, and an inhibit wire completely off its terminal on the forward/reverse switch, making intermittent contact. After tightening and/or remaking all affected connections, it was much improved but still not right below 300 RPM. The remaining issues were due to poor wiper contact in the speed control pot, and stripping it, cleaning the track and contact ring and re-tensioning the contacts resulted in the motor now running smoothly over the full speed range. The speed is slow to settle, and while part of that is probably the lag in the digital tach, I suspect that the KBIC motor speed controller isn't properly tuned as it was (allegedly) previously replaced.<br />
<br />
===Drive belt slipping===<br />
* Fixed 28/9/2022: During testing the motor after the above issue, it was noted that the chuck could be stalled, slipping the drive belt, with not much torque. The drive belt was determined to be loose and a bit worn, but still in acceptable condition. <br />
<br />
: Access for servicing the belt requires removing the control box ''(2 spades to ZVR switch disconnect the supply, speed sensor and motor simply unplug from the 'filter board')'', the motor cover, chuck guard switch assembly + wiring cover, the change gear 'A' (drive) shaft carrier assembly, and the tumbler gear assembly. See https://youtu.be/EkxlIz01BdA for disassembly/reassembly, though on our lathe, the speed encoder ring on the spindle prevents the belt cover from being fully removed without disturbing the spindle nuts. There is enough room to work with it loose, but still trapped by the encoder ring. Also, unlike the video, if the 'jack' screws under the headstock are correctly adjusted, and the studs aren't excessively bent, there is no need to make custom studs. <br />
<br />
: It turns out that our lathe was missing the M6 hex headed jack screws that press the motor down to resist the belt tension, and the motor had cocked out of position at a severe angle. I know Ian B had had considerable trouble adjusting it after the motor fault back in October 2022, and I believe it had been getting slowly worse ever since. The jack screws were probably mistaken for headstock fixing bolts during disassembly after the crash that resulted in the metal Hi/Lo gears being fitted, then lost. The penny washers on the studs had dished, so I turned them over and backed them up with smaller washers and switched to nyloc nuts so they cant back off due to vibration. N.B. there is a packing washer on the motor side on one of the studs, presumably so the shaft is true to the ways. Adjusting the motor is awkward to say the least. One has to slack the stud nuts off a lot, pry under its rear end to lift it enough to be parallel to the ways, snug the stud nuts, check alignment, then set the jack screws and their lock nuts to hold it there, and finally tighten the stud nuts. <br />
<br />
: Tension: According to Sieg, it should be possible to twist the belt 90° mid span with a light finger grip. Other sources say 1/32" - 3/32" deflection mid span with light finger pressure.<br />
<br />
===Speed display blanking===<br />
* The speed display has been intermittent, blanking and flashing 8888 and 0 at certain speeds for as long as I have been using the lathe. Finally on 18/07/2022 it failed completely, with no display. I removed the display module and bench tested it - the pins are labelled 5V GND PL PE, PE is frame ground and PL is a TTL level pulse from the speed sensor - confirming that it was in good working order. My suspicions then turned to its power supply on the 'Filter' board. With both the sensor and display unplugged, the 5V rail was found to have a only a couple of volts, but the unreg DC was 17V and stable. Replacing the 78L05 5V regulator restored the 5V rail and normal operation.<br />
<br />
: ''I conclude its been failing for a while with high load current due to speeds with more lit segments causing it to drop out, resetting the speed display, causing it to blank, lowering the current enough for the regulator to recover, then the display MCU lamp tests (8888) then re-acquires the speed, repeating ad-nauseum till the speed is changed. I don't like the design as the high input voltage results in excessive dissipation.'' <br />
<br />
: ''ToDo: Bench test display to measure its worst case current consumption, then fit an appropriate dropper resistor to reduce the 78L05 dissipation.''<br />
<br />
===Quill spinning when drilling===<br />
* The quill was tending to spin while drilling because its anti-rotation pin (a M5 dog tip setscrew) was sheered. I've removed the debris, aligned the scale with the top of the tailstock and fitted a longer M5 dog-tip setscrew to replace it, with a nut to lock it at the correct height. N.B. the pin isn't that 'meaty' so if using big drills in tough metals, to prevent shearing it, it should be backed out so the quill can be turned by hand and unwanted rotation controlled by being quick with the quill lock if it starts to spin, or even using a close fitting rod in one of the chuck key holes with plastic tube over it to protect the ways. <br />
: ''If the screw sheers again, the quill will need to be removed and the tailstock taken off the lathe so the sheered tip can be shaken out, and if the setscrew is difficult to remove it probably means the threads are mangled where it sheered. Try driving it right through with the quill out.''<br />
<br />
===Sloppy quick change toolpost locking mechanism===<br />
* Once the dovetail clamp screw was slackened, there was nothing preventing the dovetail twisting or cocking significantly, and friction with the toolholder made it tend to do so, making toolholder insertion and removal more difficult unless the clamping screw was backed off excessively. I added a compression spring around the clamp screw inside the toolpost to push the dovetail outwards so it mostly retains alignment when open, allowing toolholders to slide on or off cleanly with far less screw slackening.<br />
<br />
===Leadscrew rubbing===<br />
* The leadscrew shaft is rubbing on the insulating separator inside the control box. Unfortunately the corner of the relay on the Filter Control Board (#160) doesn't allow enough clearance. Although the friction isn't much of a problem at high reduction ratios, e.g. 16:1 power feed, it increases the stress on the change gear train, and may be problematic when threading at feeds above 1:1. ''Possibly pack out the control box mountings by a couple of mm.'' <br />
<br />
===High/Low lever backwards!===<br />
* The high-low drive gear selector behind the headstock is incorrectly labelled and differs from the manual: low gear (which we normally use) is with the lever towards the tailstock. ''I suspect that the gears in the headstock were refitted the wrong way round when it was upgraded to metal gears.''<br />
<br />
: ''ToDo: Get it reassembled the right way round during the spindle bearing upgrade!''<br />
<br />
===Carriage lock fouls top slide===<br />
* The T handscrew has been replaced with a M5 hex headed bolt, to permit access when the top slide is over it. An 1/4" drive 8mm socket is usually left on it, but needs to be removed when the full cross slide travel is needed. The small (4 jaw) chuck key is near enough 1/4" to use for it. If you need to (un)lock it while the compound is over it, you'll need an 8mm spanner. ''The [https://www.amadeal.co.uk/acatalog/Mini-Lathe-Carriage-Lock-463.html Amadeal lock screw] is in the spares tin as it was too high and fouled the compound slide.''<br />
<br />
===Tailstock locking lever loose===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock - See full image for key to screws]]<br />
* Diagnosed and fixed 10/1/2023 - In the base of the upper section of the tailstock, there are two dog tip set screws that engage with locating grooves in the counter-rotating shafts carrying the eccentric locking cams. They'd backed off, probably due to vibration. They need to be tightened till they bottom out in the groove, making sure they are '''in''' the groove, backed off half a turn so the shafts can turn easily, and locked in place. There's no facility to do so, so reassemble with weak threadlocker. Unfortunately to get to them you have to remove the tailstock base slide, which is held on by the pressure of four adjusting grub screws, which all need backing off, and one socket headed bolt from underneath so full tailstock realignment is required after reassembly, which even for a rough alignment is tedious.<br />
: <s>The tailstock locking lever is loose and can be pulled out on its axis. It works OK when fully pushed home but needs investigating. ''I tightened the grub screw as the lever was coming off its shaft, but the whole shaft pushes/pulls in and out. It works OK fully pushed in, but it seems something that is meant to retain it has failed inside the tailstock base.</s><br />
<br />
===Gear alignment issues===<br />
* Change gear alignment is poor. I've currently got a gapped washer (to clear the key) packing out the A shaft so the gears line up, but this reduces the key's engagement so is problematic due to the high loading if the gears are set up for coarser threads. <s>Also I need to turn down some penny washers to slightly less than the root diameter of the metal 20T pinions, as gear retaining washers.</s> ''The gear retaining washers for A gear and B-C stub shaft are now done, turned down to slightly under 16 mm dia. Spares in the change gear tin. ToDo: The D (leadscrew) washer requires a larger center hole, so make two more with that hole.'' <br />
<br />
===Saddle gibs loose===<br />
* Fixed 11/04/2023: I took the apron off for access (and to clean the carriage handwheel gears), and found the front sheer plate screws were completely loose. I've snugged them up some and set the opposing grub screws and got a lot of the slop out. I've re-checked the front ones, and taken up the slop in the rear ones - Unfortunately it wasn't possible to get carriage movement to have an even 'feel' over its whole travel, and its noticeably tighter near the tailstock. If light hand pressure on the side of the unlocked carriage can cause movement (with the half-nuts open), its time to readjust them again, though it should be possible to move the carriage with a firm push. <s>The saddle gibs (actually the sheer plates) were too loose, to the point that engaging a slightly stiff threading dial could cause it to self-feed, an obvious crash hazard if working near the chuck or a step in the work.</s><br />
<br />
''N.B. the lefthand front opposing grubscrew is short, (fully recessed) and unlike the others does *NOT* have a locking nut as it must clear the traverse pinion. A wrap of PTFE tape provides enough friction to keep it in place, though possibly a bit of nylon fishing line down its hole would be better.''<br />
<br />
===Excessive cross-slide backlash===<br />
* ''Mostly Fixed <s>11/10/2022</s> again 07/11/2023:'' The cross-slide screw had excessive backlash (nearly three turns), possibly due to end float, which increases the risk of loosing track of the cut depth during threading operations. If you ended up off by a turn too far in, a crash was the most likely outcome.* 02/11/2023: The backlash is back up to one turn. I suspect the cross-slide screw nut mountings are working loose again.<br />
<br />
: So it turned out that the reason the cross-slide had nearly 3mm of backlash wasn't end float, it was loose cross-slide screw nut mountings. The nut has two socket headed cap screws pulling up, one either end, accessible from the top of the cross-slide, which control the tilt of the nut to take up backlash in the nut, and an opposing grub screw pressing down on the center of the nut to make it longitudinally rigid. I gambled the cap screws weren't too far out and snugged up the grub screw, and that immediately took out over 95% of the backlash which is now down to 10 divisions or so, or 0.25 mm. Shimming the cross-slide screw collar should take out some of what's left and careful adjustment of the nut tilt should get that down to under 0.1mm.<br />
<br />
: 07/11/2023: When the problem recurred I investigated further . It is difficult to get the cross-slide nut aligned correctly as it must be at the same height as the screw which is constrained by the bearing surfaces in the bracket. With the cross-slide almost at the front limit of its travel, I removed the screw and set the nut as level as possible and visually centered in the bore, then re-fitted the bracket and screw, then adjusted the tilt till it turned freely through the backlash. I then tilted it up at the front till some drag was felt to minimise the backlash and tightened the screws to lock it in place balancing them to maintain the same feel as I tightened them. The result was 7 divisions of backlash, acceptable but not great. During normal turning operations, the load on the nut is tension on the front screw and pressure on the grubscrew, so if it slackens again due to vibration from chatter, odds are it will be the rear screw that's loosened. <br />
<br />
* Further reduction of backlash: https://youtu.be/Wu_tI29JL2Y?t=163 <br />
: Brass tinned with Pb-free solder to form a white metal bearing surface should work at least as well as the bronze used in the video. The shim washer needs to be 10 mm ID and ~14 mm OD. It isn't necessary to remove the lead screw from the cross slide, as the washer can be fitted in-situ with only the bracket removed. Its also possible to closely estimate the required washer thickness from the backlash - note the number of dial divisions of backlash, then strip down the dial and bracket and with the gibs tight enough to keep the cross-slide from moving, push and pull the screw to assess its end float. A dial indicator mounted on the cross slide probing the screw flange will give you the total end float. Subtract the end float from the backlash, than take off another thou (0.025 mm) for running clearance to get the washer thickness (assuming it seats fully in the recess). If after fitting it, snugging up the bracket screws makes the screw too stiff to turn, the washer is too thick - either make another one or try to lap it down.<br />
: TLDR: measure flange on cross-slide screw and depth of recess in cross-slide bracket (behind dial) and machine a shim washer to take up nearly all the difference.<br />
<br />
===3 Jaw chuck didn't mount properly===<br />
* Fixed 7/4/2023 by grinding the spindle nose lip. The three jaw chuck can now be installed and removed by hand with no hammering. A test bar in it now has only 2 thou runout (TIR) at the chuck.<br />
: <s>The three jaw chuck and the faceplate aren't seating properly on the spindle nose. Its too tight on the register diameter of the lip. This results in grossly excessive runout, and also makes this chuck and the faceplate a PITA to fit or remove.</s><br />
: ''The spindle nose had been abused with a hammer (before my time) which mushroomed it and may have brinelled its bearings. See '''Excessive Runout''' and '''Spindle bearings''' above.''<br />
<br />
== Manuals, Books and other resources ==<br />
=== Manuals ===<br />
The [https://wiki.richmondmakerlabs.uk/images/a/a3/Lathe_InductionNotes.pdf RML CJ18A Mini-Lathe Induction Notes]. Your mandatory Lathe Induction will cover most of this but its good to be able to refer back to it.<br />
<br />
Official [https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Amadeal CJ18A Manual], or paper copy (less complete) kept on shelf above lathe.<br />
<br />
The [https://www.chesterhobbystore.com/wp-content/uploads/2022/11/Conquest-Super-Lathe.pdf Conquest Super Lathe manual] is considerably better than the Amadeal manual and is for a near-identical machine.<br />
<br />
The [https://littlemachineshop.com/images/gallery/info/minilatheusersguide.pdf Mini Lathe User’s Guide] from LittleMachineShop.com is even more comprehensive, going into its usage in some detail, with a proper TOC, and covers both US and Metric versions of Realbull Mini-lathes. ''The only fly in the ointment is the threading section assumes a US lead screw so change gear selections and threading dial divisions will not be correct for our lathe.''<br />
<br />
[https://www.arceurotrade.co.uk/machineguides/C3-Mini-Lathe-Dismantling-and-Reassembly-Guide.pdf Sieg C3 Mini-lathe Dismantling and Reassembly Guide] "A picture story book to help you dismantle and reassemble your Sieg C3 Mini-Lathe" ''It is similar enough to ours to serve as a maintenance guide, except for the electronics, spindle drive and other headstock innards.<br />
<br />
The motor controller is a clone of a [https://acim.nidec.com/drives/kbelectronics/-/media/kbelectronics/documents/dc-drives/manuals/kbic_manual.ashx?la=en KBIC® SCR DC Motor Speed Control]<br />
<br />
=== Books ===<br />
'''Metal Turning on the Lathe''', by David A Clark, Crowood Metalworking Guides, ISBN-13: 978-1847975232 [https://www.amazon.co.uk/gp/product/B00E78RKIG Kindle Edition (£8.99)]. ''A 'free' epub can be googled for, *NOT* linked here due to dubious legality.''<br />
<br />
'''[https://archive.org/details/03screwcuttinginthelathe Screwcutting In The Lathe]''', by Martin Cleeve (a pen-name of Kenneth C Hart), Workshop Practice series #3, ISBN-13: 9780852428382<br />
<br />
'''[https://archive.org/details/15workholdinginthelathe Workholding in the Lathe]''', by 'Tubal Cain' (a pen-name of Tom Walsh), Workshop Practice series #15, Argus Books, ISBN-10: 0852429088<br />
<br />
'''[https://archive.org/details/20metalworkandmachininghintsandtips Metalwork and Machining Hints and Tips]''', by Ian Bradley, Workshop Practice series #20, ISBN-13: 9780852429471<br />
<br />
'''[https://archive.org/details/38toolandcuttersharpening Tool and Cutter Sharpening]''', by Harold Hall, Workshop Practice series #38, ISBN-13: 9781854862419<br />
<br />
'''[https://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpaperT204.pdf Cutting Fluids]''', by EC Bingham, NIST Tech. Paper No. 204, 1921<br />
<br />
=== WWW resources ===<br />
==== Mini-lathe Specific ====<br />
There's a *LOT* of mini-lathe info online. Notable sites include:<br />
* http://www.mini-lathe.com/ - A major Realbull/Sieg mini-lathe resource.<br />
* http://mikesworkshop.weebly.com/lathe-modifications.html - many mods including carriage DRO autostop, and variable speed leadscrew motor drive, cross-slide motor drive, etc. He also has a page with a bunch of accessories, toolholders etc. - http://mikesworkshop.weebly.com/lathe-accessories-and-tooling.html<br />
* http://andysmachines.weebly.com/variable-speed-controls.html - Scroll down to the 'UPDATE' section for the schematic of a very similar SCR speed control board. It also has the schematic for an earlier version of the Auxiliary Control Board (aka: 'Filter' board).<br />
<br />
==== Forums ====<br />
''with publicly accessible archives''<br />
* https://groups.io/g/7x12MiniLathe - Mini-lathe specific, active<br />
* https://www.hobby-machinist.com/forums/mini-lathe-mini-mill-information.220/ - active<br />
==== Youtube Playlists & Videos ====<br />
* Blondihacks: [https://www.youtube.com/playlist?list=PLY67-4BrEae9Ad91LPRIhcLJM9fO-HJyN Lathe Skills] (playlist) - "This is an educational series to help you learn to use your metal lathe. Watch them in order for best results! Satisfaction not guaranteed, especially if you're a cranky sort of person."<br />
* Frank Hoose (Minilathe.com) has a couple of relevant Youtube playlists:<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn7ON0jGM5UbM-KZDT56MOIp Mini Lathe Operations]<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn4nGRZaVq3wTOlvZNOmdAZ2 Mini Lathe Overview]<br />
<br />
==== General Machining ====<br />
* https://www.machiningdoctor.com/ - "THE #1 MACHINING TECHNICAL HUB"<br />
<br />
==Projects==<br />
[[File:VESA mount.jpg|thumb|Machined VESA mounting plate (left) and plate from Dell monitor stand it must match (right). The translucent washer shows the size of the original center hole.]]<br />
* My first faceplate project was boring out the center hole in a VESA mounting plate to adapt it to fit onto a surplus Dell 1708FP monitor stand. The part was centered using the tailstock dead center engaging with its original center hole. I clamped the part with studs and penny washers on the driving side of two opposite corners, with cap screws in the next slot round to trap the corners under the clamping washers, then withdrew the tailstock and dead center. After machining out the bore, I used the tip of the tool, rotating the chuck by hand, to scribe a circle for laying out the bolt holes. I finished off laying out and drilling the bolt and locating holes by hand at home, fitted it to the stand, and mounted the 2nd hand LG 24" widescreen monitor.<br />
<br />
* Another ultimately unsuccessful project was fly cutting aluminum flat bar to thickness to make custom shims for the set of carbide insert tools, for the four way toolpost. The 8 mm shank tools need ~2.5 mm shim stacks, and the 6 mm shank tools need ~4.5 mm shim stacks. Ideally I'd machine single shims, but the only stock I've got handy cleans up to only 3.2mm, and some fine shimming may be needed to fine-tune the tool height.<br />
<br />
: After sorting out the clamps so they were no longer twisting the aluminum flat bar stock, and switching to the short 45° turning SCMT06204 insert tool in the four way toolpost, to improve rigidity and get a well controlled tip radius, the finish was much improved. I'm still having problems getting an even thickness and am getting approx. 0.05mm variation, I suspect due to the aluminium bar stock distorting due to internal stresses as its surface is cut away. ''ToDo: try supergluing the stock to the faceplate before clamping to further reduce chatter and stop the warping.''<br />
: Looking back on this project a year later, its fairly obvious that the thickness variation was probably due to faceplate surface runout due to the damaged spindle nose.<br />
<br />
* Raphael has been working on a steel rocket nozzle with some assistance from myself. We have set up the rough cut chunk of ~ 50mm steel bar, faced both ends (to 50mm length) and turned the OD to 49mm to clean it up. Its going to need through drilling, probably some boring, and quite a bit of detail work on the OD. It will then need to be transferred to a jig in the drill press vice to allow a pattern of angled traverse holes to be drilled with acceptable accuracy.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_Lathe_Notes&diff=17585Ian M's Lathe Notes2023-11-15T00:56:50Z<p>IanM: /* Shimming */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br />
<br />
''Currently these notes are semi-organized and non-authoritative. As I become more experienced with the RML CJ18A mini-lathe, I'm cleaning up, extending and reorganising them. Some lathe operating experience is assumed. If in doubt, '''*ASK*''' me, Andy H<sup>*</sup> , Jonathan H or another experienced minilathe operator!<br />
<br />
''* Andy H should be asked (for an authoritative answer) any questions involving RML usage policies or acquiring tooling or materials through RML.''<br />
<br />
== The Lathe ==<br />
Our Facilities page [[Facilities#Lathe|has]]:<br />
<blockquote><br />
'''Lathe'''<br />
[[File: Lathe2.jpg |200px|right | Lathe]]<br />
In the kitchen. <br />
<br />
Marked as a CJ18A Mini-Lathe from [[https://www.amadeal.co.uk/acatalog/CJ18A-Mini-Lathe-7x14-Machine-100mm-3jaw-Metric-With-Metal-Gears-AMA_LA_CJ18_M_3_MGRB.html Amadeal]]<br />
[[https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Manual]] <br />
<br />
[[Media:Lathe InductionNotes.pdf| Induction Document]]<br />
<br />
Possible upgrades:<br />
*https://www.youtube.com/watch?v=GwT-JQLbNPA<br />
<br />
''Please do not use the lathe until you have received induction'' <br />
<br clear=all><br />
</blockquote><br />
Its a Chinese import 7x14 mini-lathe. The 7x14 refers to the maximum diameter and length of work, in inches and is only a theoretical measure of the working envelope as you loose length to the chuck + any tailstock tooling, and the diameter is over the bed, not the cross-slide. See actual specifications below. <br />
<br />
Most if not all Chinese 7x10 to 7x16 mini-lathes seem to be remarkably similar (not uncommon with Chinese products due to [https://www.bunniestudios.com/blog/?p=284 Shanzhai (山寨)] )<br />
and the OEM of our Amadeal CJ18A Mini-Lathe was probably [https://www.made-in-china.com/showroom/cheap-lathe Yangzhou Realbull Machinery Co. Ltd]. Very similar lathes are also made by [https://www.siegind.com/lathe-machine.html Sieg], but their lathes tend to be slightly less sophisticated than the equivalent Realbull models.<br />
<br />
''N.B. Many Sieg parts are known to have slight but critical differences from Realbull parts, so '''DON'T''' order Sieg spares for a Realbull lathe!<br />
<br />
== Key Specifications ==<br />
Amadeal says the CJ18A Mini-Lathe is a 7x14 model with:<br />
<blockquote><br />
* Power 550 W<br />
* Distance between centres : 350 mm<br />
* Swing Over Bed: 180 mm<br />
* Swing Over Cross Slide: 110 mm<br />
* Taper: MT3<br />
* Tailstock Taper: MT2<br />
* Chuck diameter: 100 mm<br />
* Spindle Speed: 50 - 2500 rpm ''(with digital readout)''<br />
* Spindle Bore: 20 mm<br />
* Cross slide Travel: 65 mm<br />
* Range of Metric Threads: 0.5 - 2.5mm.<br />
</blockquote><br />
* The lead screw is metric, pitch 1.5 mm.<br />
* The spindle center is 90.6 mm above the flat of the bed (measured).<br />
<br />
Even though the compound and cross slide handwheels appear to be calibrated in thousandths of an inch, as ours is a metric machine, they only approximate that. One turn of a slide handwheel is 1mm advance, and they have 40 divisions, so each division is 0.025 mm, (approx. 0.984 [https://en.wikipedia.org/wiki/Thousandth_of_an_inch thou]). Similarly, the tailstock quill advances 1.25 mm per handwheel turn, which has 50 division dial, giving the same 0.025 mm divisions, but only 4 turns per 5 mm. The carriage handwheel is awkward - it moves approx. 19.2 mm per turn, and doesn't have a dial scale.<br />
<br />
== Notable Accessories ==<br />
We have:<br />
* [https://www.amadeal.co.uk/acatalog/160mm-Face-Plate-for-the-4-Mini-lathe-AMA_AC_CJ18A_FP160RB.html#SID=129 160 mm (6 1/4") Faceplate]<br />
* 100 mm (4") three jaw self-centering chuck (OEM standard) 22.5mm bore, with inside and outside jaw sets<br />
* 100 mm (4") four jaw (independent) chuck with reversible jaws (8 TPI screws)<br />
* Tailstock drill chuck (max. 13 mm dia.)<br />
* Live center for tailstock (+ OEM fixed center) <br />
* Four way Tool Post (OEM Standard)<br />
* [https://www.amadeal.co.uk/acatalog/Quick_Change_Tool_Post_for_the_mini-lathe.html Quick Change Tool Post] + 3 tool holders<br />
* [https://www.amadeal.co.uk/acatalog/Fixed-Steady-for-Mini-Lathes-AMA_AC_CJ18A_FSRB.html#SID=145 Fixed Steady Rest]<br />
* [https://www.amadeal.co.uk/acatalog/Travelling-Rest-for-Mini-Lathes-AMA_AC_CJ18_TSRB.html#SID=144 Travelling Steady Rest]<br />
<br />
''You'll find all of the above on the shelf above the lathe, with the accessories in the wooden box, apart from the steadies, which live next to it. Change gears, spare parts, and most cutting tool tips/blanks are in labelled white rectangular tins behind the lathe.''<br />
=== Measuring Tools ===<br />
We have:<br />
* Various dial indicators - the one with the adjustable magnetic base stand is the most convenient for most lathe setup work.<br />
* 25mm micrometer (in little grey case)<br />
* Grey case containing set of measurement tools including dial calipers, micrometer, steel rule (metric & inch), engineers square, and a fish-tail gauge<br />
<br />
''We currently lack''<br />
* ''A tool height setting gauge''<br />
<br />
=== Hand Tools ===<br />
Some common tools needed for normal use are kept with the lathe, in or attached to the wooden accessories box:<br />
* 2 mm Allen key - adjusting cross-slide and compound gibs<br />
* 4 mm Allen key - quick change toolholder tool clamping screws + height adjust, tightening dials<br />
* 5 mm Allen key - four way toolpost tool clamping screws, engaging/disengaging threading indicator<br />
* 6 mm Allen key - locking/unlocking quick change toolholder<br />
* 8 mm spanner - locking carriage when 8 mm socket can't be used, locking gib adjuster nuts <br />
* 13 mm spanner - changing chucks, locking steady rest jaws<br />
* Very long needle nose pliers - for grabbing swarf safely, holding one end of emery cloth safely so you can keep your fingers away from the jaws, and extricating small objects from awkward places.<br />
<br />
== Change Gears ==<br />
[[File:BC puller 1.jpg|thumb|Custom puller for B-C stub shaft]] [[File:BC puller 2.jpg|thumb|Pulling the B-C stub shaft]]<br />
See "Conquest Super Lathe" manual ([[#Manuals|below]]), section '''4.7 Change Gears''', PDF pages 28-29, but see below for mesh adjustment. The LittleMachineShop.com "Mini Lathe User’s Guide" (also below) section '''Threading''' gives a far better explanation, with pictures and diagrams, but its for a lathe with a US 1/16 inch pitch leadscrew, not a metric 1.5 mm pitch one like ours, so you *MUST* ignore all the tables in that section, replacing them with metric mini-lathe (with 1.5 mm pitch leadscrew) equivalents. <br />
<br />
We have the following tooth count gears: 20,20, 30, 35, 40,40, 45, 50,50, 60,60, 80,80<br />
which consist of the OEM power feed gears + the metric change gear set. Apart from the metal 20 tooth pinions, they are all plastic, probably Delrin if the molded in 'POM' marking can be trusted, but possibly plain Nylon 6, and are metric Module 1.<br />
<br />
If we wanted to add the capability to cut US/Imperial threads we'd need to buy additional 55, 57 and 65 tooth gears, and possibly a 21 tooth metal pinion.<br />
<br />
CGTK's [https://www.cgtk.co.uk/metalwork/calculators/changegears/minilathe?gears1=20,20,30,35,40,40,45&gears2=50,50,60,60,80,80&gears3= Change Gear Calculator] ''(link preloaded with our gear list)'' is useful if you don't want to calculate the ratios from first principles. Not all suggested combos will physically fit.<br />
<br />
* Take care *NOT* to loose the keys in the A and D shaft keyways - turn each shaft till the keyway is up before removing the gear. <br />
* The B and C gears are coupled by a hollow stub shaft (with an integral key), which is so tight in the gears it has to be pressed or driven out - I've made a puller just for this task, kept in the change gears tin.<br />
* The center of the B-C stub shaft *MUST* be lubricated where it runs on its pin on the change gear banjo bracket, with grease or heavy oil. ''Seizure of the stub shaft due to running dry is a frequent cause of catastrophic mini-lathe geartrain failures!''<br />
* Don't get oil on the change gears as it can cause plastic gears to crack. Only PTFE drylube or plastic compatible white grease should be used on their teeth. <br />
* Adjust the B-C pin position in the straight slot first to set the C to D gear mesh, tighten its nut, then swing the whole banjo about the D shaft boss to set the A to B mesh, and finally tighten the banjo clamping nut.<br />
* Check both gear meshes have running clearance by turning the chuck by hand enough to complete one full turn of the leadscrew, and by attempting to turn the intermediate gear(s) to assess backlash, If excessive resistance is felt or if there's significant backlash, readjust the gears. If you have difficulty judging the mesh, a strip of 80 gsm copier paper (approx. 0.1 mm thick) wound into the meshing teeth before tightening the stud or banjo will give appropriate clearance once removed. Once setup, check the gears run quietly under power.<br />
* If the sum of the tooth counts C+D is the same as for the ones you just removed and they were correctly meshed, you don't need to move the stub shaft pin. If A+B is <u>also</u> the same, you don't need to move the banjo. e.g. If it was set up for 16:1 reduction power feed, 1 mm (40:60 - 50:50) for M6 and 1.5 mm (e.g. 40:60:40) for M10 pitches can thus be achieved by only swapping gears. <br />
<br />
''The change gears, puller, etc. and a box spanner for the banjo nut are kept in a white rectangular tin behind the lathe.''<br />
<br />
=== Power Feed ===<br />
When used for turning with power feed, the change gears should be set for a 16:1 reduction (A:20 : B:80 - C:20 : D:80) using the pair of small metal 20 tooth pinions and the 80 tooth plastic gears (largest in set), for a feed of 0.09375 mm per turn (1.5 mm/16). Unless continuing your threading project the next session, please re-fit the 16:1 power feed set after threading so the power feed is ready for use. <br />
<br />
* *ALWAYS* leave the feed direction selector lever in its neutral (no feed) position, and the half-nuts open after use.<br />
* *ALWAYS* check the carriage lock is disengaged before engaging power feed. Unlock the carriage after use. <br />
<br />
=== Threading Dial ===<br />
The threading dial is an aid to re-engaging the half-nuts at the right moment so the tool will retrace its previous path cutting deeper, rather than offsetting axially some fraction of the thread pitch and ruining your work. Its based on the concept of the lowest integer multiples of the leadscrew and thread ''(being cut)'' pitches that exactly match, but for mechanical simplicity it only covers certain selected multiples of the leadscrew pitch.<br />
<br />
We have a choice of three pinion gears:<br />
{| class=wikitable<br />
|+ Threading dial Pinion Gears<br />
|-<br />
! Teeth !! Colour Dot !! Usable lines !! OD gear !! Dist. per turn<br />
|-<br />
| 14 || Red || 1,7 || 7.51 mm || 21 mm<br />
|-<br />
| 15 || Orange || 1,5,9 || 8.05 mm || 22.5 mm<br />
|-<br />
| 16 || Green || 1,4,7,10 || 8.37 mm || 24 mm (2 mm/div)<br />
|}<br />
They are now colour coded, with a paint dot on the gear end face ''(the only non-wear surface)''. The 16 tooth one is normally left on the lathe, but disengaged when not threading to minimise wear on the lead screw. The others are kept in the Change Gear tin.<br />
<br />
There's a threading dial 'pickup' calculator here: https://www.cgtk.co.uk/metalwork/calculators/threaddialindicator <br />
<br />
Initially select ''Lathe:'' '''Custom''', and enter the following below:<br />
* ''Units:'' '''Metric'''<br />
* ''Lead Screw Pitch (mm):'' '''1.5'''<br />
* ''Thread Dial Indicator Gear Teeth:'' '''16,15,14''' <br />
* ''Lines on Thread Dial Indicator:'' '''12''' <br />
* ''Line Marking:'' '''Every Line Numbered'''<br />
Note the teeth list is entered in reverse order so the resulting table highlights any required pinion changes.<br />
<br />
N.B. The dial is only friction clamped to the pinion by its center screw. If you have any reason to suspect it may not be properly aligned: <br />
# With the power off and the carriage unlocked, engage the feed direction lever upwards. You'll probably need to turn the chuck by hand to get it to engage.<br />
# If the threading indicator isn't already engaged, loosen the threading dial support block bolt, pivot the block to engage the pinion with the leadscrew and retighten the bolt.<br />
# Engage the half nuts, again turning the chuck by hand till they drop in. <br />
# Turn the chuck a couple of turns, top towards you to take up any backlash, then lock the carriage, taking care not to push it left while locking it.<br />
# Loosen the screw securing the dial to the pinion.<br />
# Align the '1' line of the dial with the index line, by rotating the dial clockwise, then retighten the screw.<br />
# Don't forget to disengage half-nuts and unlock the carriage!<br />
<br />
The above instructions should result in the half-nuts engaging cleanly when exactly on any valid line when threading towards the headstock. If it is required to thread away from the headstock, there will be a slight offset from the line due to backlash between the spindle gear and leadscrew, so engage slightly early.<br />
<br />
Changing the pinion:<br />
# Loosen the threading dial support block bolt and disengage from the leadscrew.<br />
# Undo dial center screw, and remove it and the dial, dropping the old pinion out the bottom.<br />
# Oil the shaft of the new pinion with a drop of light oil and insert it from below, gear end down.<br />
# Refit dial and screw.<br />
# Check the dial and pinion turn freely with minimal resistance.<br />
# Align as above.<br />
<br />
== Tailstock and Steadies ==<br />
These are mostly used to support long work ''(long with respect to its diameter)'' to improve rigidity, increasing accuracy and reducing chatter. The Tailstock quill is also used with a drill chuck for drilling.<br />
=== Tailstock ===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock base]]<br />
The tailstock can be offset to turn shallow tapers between centers. We don't currently have the accessories to turn between centers, namely <s>a MT3 dead center for the spindle, or</s> any drive dogs for the work. Also realigning the tailstock after turning a taper can be a PITA. The photo shows the tailstock adjusting screw locations ''(C - Lateral, and D - Skew)'' and the block on the baseplate they engage with. Adjustments can only take effect when the tailstock locking lever is eased to take the pressure off the baseplate. As we don't have a MT3 center, one has to turn a fresh point on a test workpiece for a rough tailstock alignment reference. Fine alignment, to avoid inadvertent taper turning, can be done by mounting a long precision ground bar between the chuck (or preferably a center in the spindle), and a dead center in the tailstock and sweeping it with a dial indicator on the carriage. Finally a test cut should be taken at either end of a bar between centers, and the diameters checked with a micrometer. Assuming the bed has previously been properly levelled and shimmed to take out twist ''(not the case at RML as we don't have it bolted down)'', any remaining difference in diameter will be double the tailstock offset, smaller at the tailstock being offset towards the front. Fine adjustment cant be achieved by jacking with the screws, its best to ease the adjusting screws, bump the tailstock into alignment then take up the screws again, checking the alignment is maintained when the tailstock is unlocked and relocked. There is no vertical adjustment, though shims can be added between the tailstock and its base.<br />
<br />
==== Tailstock Quill ====<br />
There is a metric/imperial scale on the top of the quill, read against the end of the tailstock, for depth measurement when drilling. The tailstock quill has a 1.25 mm pitch thread and a 50 division dial. Each division is therefore 0.025 mm, and it only takes 4 full turns of the handwheel to move the quill 5 mm. <br />
<br />
To eject MT2 taper tooling and centers from the tailstock, wind the quill all the way in.<br />
<br />
N.B. The quill anti-rotation pin (dog-tip setscrew + locking nut in top of tailstock near to the quill lock) is only M5. It will sheer if a large diameter drill jams in the work. Please back it out clear of its keyway if using large drills, and use alternative methods of preventing chuck rotation. To re-engage it, crank the quill out till you can see the keyway, align it with the screw and screw in the screw till it gently bottoms out, then back it off a quarter turn. Try twisting the quill to check its properly engaged, then tighten the locking nut gently to hold the screw in position clear of the bottom of the keyway.<br />
<br />
=== Steady Rests ===<br />
We have two, both with brass tips that must be kept lubricated during use.<br />
<br />
The fixed steady mounts on the ways, and is most useful when turning longer work that wont fit through the spindle bore. Adjustment is critical, and the surface the tips run on must be smooth and concentric, as any misalignment that forces the work off center will result in the work wobbling in the chuck, marring it, with a high risk of it becoming un-chucked, which can be dangerous at speed.<br />
<br />
The travelling steady mounts to the headstock side of the carriage to locally resist the deflection of thin long work, due to the cutting forces. It only has two tips, to resist climb, and deflection away from the tool, and requires readjustment after every cutting pass.<br />
<br />
== Tooling and Tool Holders ==<br />
'''Key dimensional data:'''<br />
* The quick change holders accept up to 10 mm shank tools. <br />
* The four way toolpost has 50 mm long sides, a seat width of 15 mm and can clamp tools of up to 5/8" (15.875 mm) shank ''(check this)'', but the slot base is only 10.4 mm below the spindle center so cannot be used with >10 mm shank tooling unless it has a dropped tip. Large tooling with a centered tip is also problematic as you run out of height above the shank when trying to shim to match the spindle center height. <br />
<br />
===Quick Change Toolpost===<br />
I've got the quick change toolpost and toolholders setup for mostly easy use. The three toolholders came with cantilever height setting arms which historically haven't been installed as the supplied fixing screws were too short. That's all now sorted out and a HSS RH turning tool and a HSS hand-ground grooving/parting-off tool are now mounted in two of the holders and set to height. The third is kept free for other tools. <br />
<br />
The quick change toolpost has been modified with a spring to press the dovetail clamp outwards and help stop it twisting or flopping about to ease toolholder fitting and removal. The dovetail clamp (socket headed screw on toolpost side opposite dovetail) feels a bit stiffer than before, but will take less than half a turn to go from open (with the toolholder lifting out or dropping in easily) to fully clamped. As there is so much less clearance in the open position you should no longer need to wiggle the toolholder while clamping it to get a consistent height. If the dovetail clamp ever gets misaligned, twist it straight by eye, slacken off a bit further than usual to get a toolholder on, clamp it to align the dovetail then release, reseat the toolholder and re-clamp to ensure its at its preset height. You cant adjust the height by 'jacking' with the height screw due to its offset leverage. Instead, back off the height screw and hold the toolholder at the desired height while locking the dovetail clamp, then adjust the height screw (and locking nut) to hold it there, then check it doesnt change height significantly when you unclamp and reclamp the dovetail. <br />
<br />
Unfortunately the OEM height setting screws foul the toolpost locking nut handle. Currently, if you need to swap toolposts you will have to first remove the quick-change tool holder from the post. There is enough nut handle swing to allow the quick change toolpost to be unclamped and rotated to fine set the tool angle without removing the toolholder. It also seems the mating surfaces may be slightly out of square, as if you rotate the toolpost 90° or 180°, the nut swing may be insufficient to re-clamp it without removing the toolholder to do so. Add a M10 washer under the locking nut if the handle ends up pointing in an undesirable direction! A thin M10 washer is kept with the toolpost collar for this purpose, and will shift the handle position by about a third of a turn. <br />
<br />
''ToDo: Make a taller nut of a similar pattern, to clear the height setting screws.''<br />
<br />
===Four Way Toolpost===<br />
The OEM four way toolpost is significantly more rigid than the quick change toolpost + holders because it has fewer and thicker parts and less overhang. Therefore the four way toolpost should be used when using carbide tooling. It requires shimming under the tool to set the tip height to the spindle center height - see below. The tool shanks are mostly significantly less than 15 mm wide, so need to be centered under its clamping screws, tempting as it is push the shank in for full side contact with the toolpost. If possible clamp the shank with all three screws not just two.<br />
<br />
==== Shimming ====<br />
We typically only mount up to two tools, and want maximum rigidity, so use 50 mm x 15 mm shims, (the full seat area), preferably with deburred edges and radiused corners so they aren't a hazard to the operator.<br />
<br />
We have pre-cut and marked shims of the following thicknesses: <br />
* 1x 3.23 mm, 2.42 mm, 1.56 mm, 0.32 mm, and 0.25 mm<br />
* 2x 1.00 mm, 0.77 mm, 0.12 mm, 0.11 mm, 0.10 mm and 0.05 mm<br />
* 4x 0.53 mm<br />
<br />
Our shims are mostly found materials (hence the awkward thicknesses) and are mostly a mixture of aluminium and steel, with a couple of GRP ones. The toolpost seat '''<u>must be absolutely clean</u>''' to avoid embedding debris in the aluminium or GRP shims, to get a consistent height and avoid tilting the tool - wipe it every time you change a tool! Put the thin shims at the bottom of the stack to avoid the tool shank edges creasing them. Shims are kept in a little yellow plastic box with a clear lid, near the carbide tools case.<br />
<br />
I made a tool height setting gauge (T shaped black acrylic with steps in its sides) which can be used to check the tool tip height matches the spindle center height using either the flat of the ways or the saddle as a reference. The tool tip should just fit under the lip of the appropriate step, with the T arms across the ways flats or on the saddle.<br />
<br />
''ToDo:'' <br />
<br />
* ''Cut more shims neatly, mark them with their thickness.''<br />
* <s>''Do test cuts and start noting shim stack-ups for various tools.''</s><br />
* ''Organise shim storage!''<br />
<br />
=== HSS Tools ===<br />
[[File:Tool Bit Geometry.jpeg|thumb|Single point cutting tool geometry]]<br />
Our HSS tools are made from 8 mm square bar stock, hand-ground to tip profile in-house. See LittleMachineShop's [https://littlemachineshop.com/images/gallery/instructions/grindingtoolbits.pdf Grinding Tool Bits] notes. <br />
<br />
I've installed our usual HSS LH turning and parting off tools in two of the quick change holders and set the heights correctly. There are a couple of other HSS tools or tool blanks knocking about. Taking heavy cuts turning steel (even with good cutting oil) blunts HSS tools fairly quickly, which are time-consuming to re-sharpen nicely without a dedicated tool & cutter grinder with appropriate jigs. Its worth noting that the usual 'speeds & feeds' tables are commonly based on surface speeds expected to give a half hour (active cutting) tool life before resharpening.<br />
<br />
I touched up the LH turning tool by lapping on wet & dry (silicon carbide) paper on glass (Aka: [https://en.wikipedia.org/wiki/Scary_sharp 'Scary Sharp']) working upwards through the grits 200, 400, 600 and finally 1000, initially 'bluing' the surfaces to be lapped with a marker pen to see which areas needed taking down more. The end of the tool was significantly uneven so I touched that up freehand on the bench grinder to flatten it when it became apparent that 200 grit lapping wasn't cutting where it needed to. There was an existing micro-bevel on the leading side, which I kept. Finally I 'dubbed' the leading corner vertical edge on the 1000 grit to give it a very slight nose radius. A test cut on brass gave a very nice finish when turning.<br />
<br />
''Ian B has purchased some spare 8mm HSS tool blanks - talk to a lathe trainer if your proposed lathe work needs custom ground HSS tooling.'''<br />
<br />
=== Brazed Tungsten Carbide Tools ===<br />
Somewhat of a half-way house between hand ground HSS tooling and insert tooling with the disadvantages of both and some more besides - e.g. they are much harder to sharpen. So why do we bother? Some tool geometries would be awkward and tedious to hand grind, and Chinese import brazed carbide tooling is about half the price of similar HSS tooling, and far more readily available. Also, for space constrained tooling like boring bars, if you want carbide, for insert tooling, the size of the insert and its clamping seriously limits the minimum hole diameter you can work in. I have purchased a set of 3/8" shank brazed carbide tipped boring bars, but we currently cant sharpen them, due to lack of a diamond grinding wheel. <br />
<br />
=== Tungsten Carbide Insert Tools===<br />
Decoding ISO insert tooling part numbers: https://www.cutwel.co.uk/blog/learn-the-turning-tool-iso-code-system<br />
[[File:Carbide set.jpg|800px|thumb|left|Our set of Tungsten carbide insert lathe tools (before the new inserts were fitted)]]<br />
<br />
{| class=wikitable<br />
|+ Tools, left to right, (+ last across top):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| SSKCR0610H06 || 75° through boring || SCMT06204 || Long || 6 || 6.34 || ''4.33''<br />
|-<br />
| SSSCR0610H06 || 45° deep facing, internal chamfering || SCMT06204 || Long || 6 || 6.13 || ''4.58''<br />
|-<br />
| SWUCR0610H05 || 93° boring, deep facing || WCMT050308 || Long || 6 || 6.22 || ''4.48''<br />
|-<br />
| SWGCR0810E05 || 90° RH turning & facing || WCMT050308 || Short || 8 || 8.25 || '''2.45'''<br />
|-<br />
| SSSCR0610E06 || 45° turning, chamfering || SCMT06204 || Short || 8 || 8.75 || ''1.93''<br />
|-<br />
| SSBCR0610E06 || 75° RH turning, chamfering || SCMT06204 || Short || 8 || 8.72 || ''1.98''<br />
|-<br />
| LW0810R-04 || 60° external threading || JCL15-120 || Short || 8 || 7.44 * || ''3.28''<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || 8.23 || ''2.5 ?''<br />
|-<br />
| LN0813R-04 || 60° internal threading || JCL15-120 || Long || 7.95 || 7.44 * || ''3.28''<br />
|}<br />
<br />
{| class=wikitable<br />
|+ More Tools, (loose in tin):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || ~8.5 (not in use) ||<br />
|-<br />
| [https://www.glanze.co.uk/product/glanze-12-mm-60-degree-metric-internal-threading-tool/ Glanse SIR0012K11] || 60° internal threading bar || 11IRA60 || Long || 12 dia || ??? || ???<br />
|}<br />
''Shim stack heights in bold are tested, in italic are only calculated.'' ''Tip heights marked * are with new JCL15-120I inserts. The single remaining plain JCL15-120 insert has a slightly higher tip height.''<br />
<br />
Carbide tooling typically requires two to three times more speed than HSS and at least a couple of 'thou' depth of cut for best results.<br />
<br />
Chatter can rapidly kill carbide tooling by chipping the cutting edge. To improve rigidity and reduce the risk of chatter, the cross-slide and compound gib screws need to be well adjusted so there is minimal play in the slides, tool stick-out should be minimised, the four way toolpost should be kept over the cross-slide, and the work should be kept close to the chuck (or otherwise supported by tailstock or steady rest) to avoid excessive deflection.<br />
<br />
Thermal shock is almost instant death to carbide, and when dry cutting the insert tip can run very hot, so do not add extra cutting fluid manually during the cut. Pre-apply what you need, evenly, before starting the cut.<br />
<br />
Parting off or facing to center is high risk - if the tool tip is even slightly below center or if tool or work deflection takes it below center, the work will tend to climb over the tool tip as the cut approaches center, breaking the insert. To avoid this, the tool should be shimmed slightly above center, sufficient to allow for work and tool deflection, and unless very close to the chuck, a steady should be used. Its often preferable to part to a couple of mm dia. remaining then stop and saw through the remainder. Parting off hollow parts is much lower risk.<br />
<br />
Further investigation of the Tungsten carbide insert tool height situation is not encouraging - the so-called 'set' in question does not have a consistent tip height ''(see above table)''! In a real set, the insert seats *should* be machined allowing for the insert thickness to bring all the cutting edges to the same height with respect to the shank underside. However if you place them tip to tip on a table its easy to see there is considerable height variation, so they need to be individually shimmed (or at best, one machined shim will only be right for two or three tools). At this time we don't have dedicated shim stacks for each tool.<br />
<br />
A 2.42 mm thick shim brings the SWGCR0810E05 90° RH turning & facing tool almost exactly to center height, and good results were obtained turning 1" steel pipe. However facing 50mm steel bar stock to center found it to be slightly low, leaving a fractionally under 0.05 mm 'pip' so it needs another 0.03 mm to bring it fractionally above center. Fractionally too high is generally preferable to fractionally too low, due to tool deflection, so adding an 0.05 mm shim to the stack should produce optimum results.<br />
<br />
==== Inserts ====<br />
Ian B has purchased the spare inserts we needed in sets of five. He even was able to get the CK3 parting-off inserts which had been difficult to source!<br />
<br />
Inserts used in above tool set:<br />
* 3x SCMT06204 (square, indexable) https://www.rdgtools.co.uk/acatalog/SCMT-06-Carbide-Insert.html<br />
* 2x WCMT050308 (triangular, indexable) https://www.rdgtools.co.uk/acatalog/WCMT-05-T3-08-5XTIP-8813.html<br />
* 2x JCL15-120 (60 deg threading point) https://www.rdgtools.co.uk/acatalog/X5-JCL-15-120L-THREADING-TIPS-60-DEGREE--X5-TIP---23455.html<br />
* CK3 (parting off) https://www.rdgtools.co.uk/acatalog/CK3-CARBIDE-TIPS---PARTING--BOX-OF-5PCS--9437.html<br />
<br />
Inserts used in other tools:<br />
* 1x CK3 (as above) also missing from spare parting off tool<br />
* 1x 11IRA60 in Glanse threading bar + 1x spare<br />
<br />
=== Drills ===<br />
Various sizes of center drills are kept in a plastic bag next to the wooden accessories tray. There's also a small box of 2.5 mm center drills.<br />
<br />
We have a set of 11 TiN coated HSS drill bits from 1.5 to 8 mm, (in a cylindrical plastic index box) for tailstock drilling of brass, aluminium and non-abrasive plastics. To keep them sharp enough for the precision work we expect from the lathe, please don't use them for steel or reinforced plastics, and don't borrow them for non-lathe use. Metric and US [https://littlemachineshop.com/reference/numberdrillsize.php numbered]/[https://littlemachineshop.com/reference/letterdrillsize.php lettered] general use HSS drill bits are kept in two red metal index boxes next to the drill press.<br />
<br />
== Using the Lathe ==<br />
=== General ===<br />
A cutting speed chart for HSS tooling, published by Model Engineer magazine can be found [https://www.model-engineer.co.uk/sites/7/documents/cutting%20speed%20chart.pdf [here<nowiki>]</nowiki>]. The second row is the target feed rate and the rest of the chart, apart from the diameter column is RPM.<br />
<br />
For carbide tooling cutting iron and steels, recommended speeds are generally three times higher than for HSS, but the CJ18A 2500 RPM max. spindle speed (in high gear) means you can only reach the optimum speed range for over 15 mm dia work. For small diameter work, HSS tooling may well be a better choice.<br />
<br />
An online metric speeds calculator is here: https://www.cgtk.co.uk/metalwork/calculators/cuttingspeeds <br />
<br />
How to do the maths to calculate speeds and feeds: https://www.cutwel.co.uk/blog/speeds-feeds-made-easy<br />
<br />
Making dimensioned parts is primarily done by touching off the tool tip on a reference surface (with the lathe stopped, turning the chuck by hand), zeroing the handwheel dial, then manually counting turns and divisions. When backing off the tool its best to do so by exactly one whole turn so you don't forget the previous dial position. Stopping and measuring the work before taking the final cuts is essential if high accuracy is required. ''I've changed out the dial setscrews for flat tip ones with a tiny slug of solder under them so the dials are now friction fit on their shafts. i.e. if you hold the handle firmly taking up the backlash in the direction of cut, you can zero the dial just by grabbing and twisting it.''<br />
<br />
Carriage movement is less easy to measure as the handwheel is uncalibrated and advances an awkward bit over 19.2 mm per turn. Your options here when shoulders or other features must be exactly positioned are, in order of increasing accuracy: <br />
* Use measuring instruments, scribe the work at the desired length then work to the scribed line. Its often convenient to black the work with a permanent marker, then scribe with the tool tip, turning the chuck by hand.<br />
* for short distances, lock the carriage and use the compound, set parallel to the work<br />
* Set up a long travel dial indicator to measure carriage motion. <br />
N.B. with the leadscrew stopped, and the threading dial engaged, with its default 16 tooth gear, it will make one turn for every 24 mm of carriage movement (2 mm/div). This isn't accurate enough for positioning but is sufficient to check you aren't out by a whole mm or more.<br />
<br />
Do not allow any solvents to contact the chuck guard clear plastic as it will make the plastic brittle, or even craze it, and try to avoid melting it with the work light!<br />
<br />
=== Slide Locks ===<br />
* The carriage can be locked to the ways using the M5 hex screw through the top of the saddle to the left of the cross-slide. Double check the leadscrew is disengaged and the half-nuts open before locking it. Lock it when facing.<br />
* The cross slide can be locked by a M4 socket headed cap screw just in front of its middle gib screw. Locking the cross slide is helpful when turning very shallow conical features where the cross slide handle is in the way of the compound.<br />
* The compound slide can be locked by a M4 socket headed cap screw in line with the edge of the toolpost mount on the side with the gib adjustment screws. In normal use it should be kept backed off half a turn but it is desirable to tighten it for parting off operations to keep the resulting end faces flat.<br />
<br />
=== Chucks and Chuck Jaws ===<br />
==== Terminology ====<br />
* Inside jaws have steps on the outside to grip the ID of hollow work, but can also be used as outside jaws on small diameter parts (i.e. that fit through the spindle). <br />
* Outside jaws have steps on the inside to grip the OD of the work.<br />
* Universal chucks have a scroll plate with a spiral screw thread that moves all the jaws.<br />
* Independent chucks have individual adjusting screws for each jaw.<br />
<br />
==== The Chucks ====<br />
* The three jaw universal chuck can only grip near round or hexagonal work, which it centers, but its concentricity is not perfect so e.g. if you reverse the work and continue turning at the same diameter from the other end, you will see a line where the turned surfaces meet. It has separate sets of inside and outside jaws, and we normally keep the inside set installed to use as outside jaws for small diameter work.<br />
<br />
** Our jaws are individually numbered, stamped in the groove. They must be fitted in the correct sequence. The jaw slots are not clearly marked. Lowest runout for small dia. parts is achieved if you fit the jaws with #1 anticlockwise of the makers mark, then continue anticlockwise for #2 and #3.<br />
** A large strong rubber band is a great help getting all the jaws started on the scroll together - with slots #1 and #3 above the centerline and the scroll thread outer tip between #1 and #3, insert jaws #1 and #2 and put the rubber band round them to keep them in their slots. Insert jaw #3 and stretch the rubber band over it to hold it up into its slot. If the scroll was positioned correctly, all jaws should be at the same initial radius. The jaws can now be cranked in with the chuck key and they should all engage in step so they meet in the middle.<br />
:: ''Mini-lathe.com have the best instructions for [https://www.mini-lathe.com/mini_lathe/chucks/chucks.htm#Installing_Chuck_Jaws changing the jaws].'' <br />
<br />
* The four independent jaw chuck can grip most roundish or squarish work, which can either be carefully centered by the user, or deliberately gripped off-center. <br />
** Its jaws are reversible so can be swapped from inside to outside by simply cranking each jaw out and reinserting it the other way round, one at a time. DON'T move the jaws to different slots as they are likely to bind.<br />
** When setting up to face the sides of rectangular objects held crossways, it may be helpful to use both inside and outside jaw orientations, in symmetrical opposing pairs.<br />
** Its screws move their jaw 1/8" (3.125 mm) per turn<br />
<br />
* The jaws must '''never''' protrude from the chuck OD by more than one step, and for safety, its preferable they don't protrude at all, as they make the gap between the front of the bed and the chuck body an even more unforgiving meat grinder, and as the number of teeth engaged with the scroll or screw decreases, they loose strength, just when you need it the most to grip larger/heavier work. <br />
<br />
''Neither chuck is well suited to gripping tapered work safely. When seating work that doesn't quite fit through the chuck bore (which is larger than the 20mm spindle bore limit), be careful that it isn't seating on the chamfered edge of the chuck bore as it is far to easy to get the work slightly cocked so it doesn't run true.''<br />
<br />
==== Changing Chucks ====<br />
* When changing chucks, use the small grey plastic mat to protect the ways under the jaws in case you drop the chuck.<br />
* The spindle nose has two patterns of holes - the three hole pattern is for the three jaw chuck and the faceplate, and the four hole pattern is for the four jaw chuck. One hole is shared between the patterns, and is marked on the spindle nose.<br />
* To fit a chuck:<br />
** First check that the spindle nose and chuck back and recess are free of swarf, grit or other debris. Any foreign objects will tilt the chuck causing excessive runout and may mar the surfaces.<br />
** Remove the nuts and split lock washers from its studs, line its studs up with the hole pattern (preferably with the stud nearest anticlockwise to the makers mark through the marked spindle hole), fit and hold it in place with your right hand, and with your left, get the lock washer and nut on the top stud, and take up the slack.<br />
** One one nut is on, you no longer have to worry about dropping it, and can work round fitting the remaining washers and nuts, taking up the slack on each as you fit it. <br />
** Next, work round again getting them all finger tight, then tighten them gently, and finally work round fully tightening them. <br />
* Removal is the reverse of refitting. Put the washers and nuts back on the chuck's studs so they don't get lost.<br />
<br />
=== Faceplate Work ===<br />
Faceplate work is probably the most dangerous operation you can (or rather should) perform on a lathe. The working area is a large diameter spinning surface with protruding clamps to fixture the part that it is impractical to guard. Protruding clamps, studs, nuts etc. are very difficult to see at speed.<br />
<br />
'''Treat the faceplate with great respect and caution if you wish to continue to be able to count to ten on your fingers!''' <br />
<br />
The 65 mm cross-slide travel vs the 80 mm faceplate radius is a serious limitation that may require creative compound, toolpost and tool setups for larger parts, and doing full face cuts in two sections.<br />
<br />
''It is common practice to skim the faceplate to ensure it runs true. We have not (yet) done this, and wont till the spindle is in better bearings and the nose reground to minimise runout.''<br />
<br />
==== Clamping ====<br />
Open ended/sided clamps should be oriented so that cutting forces drive the work towards the clamping bolt/stud, not out from under the clamp. Minimize the protruding length of thread past the clamping nut, if necessary using sacrificial bolts or studs you can cut to length, or even using a long M8 stud for one of the faceplate mountings, so you can get a clamp nearer to the faceplate center. Double-check all clamps are secure, manually turn the faceplate to check the work and clamps clear the ways, top-slide and toolpost, and stand out of the 'line of fire' (a disc extending from the faceplate) when spinning up the work for the first time. <br />
<br />
If you need to machine close to a clamp, consider marking a safe limit circle on the faceplate and work with a marker pen to make it easier to see how close the cutting tool is to crash disaster. <br />
<br />
I strongly advise reading chapter two of Tubal Cain's book "Workholding in the Lathe" several times before your first faceplate setup, and if possible get another experienced lathe user to check your first few setups before spinning them up.<br />
<br />
==== Chuck Guard Removal ====<br />
The faceplate is too large diameter to fit under the chuck guard, but the guard has an interlock switch wqhich must be closed for the lathe to run. The guard is now fitted with wing nuts so it can be removed allowing the the interlock switch to close when using the faceplate. It *SHOULD* *ALWAYS* be refitted if a chuck is fitted, except when turning work too large to clear the guard. <br />
<br />
''The chuck guard is primarily there to make it very difficult to start the lathe without removing the chuck key and to reduce the area of large diameter spinning surface exposed. It may slow down the projectile if a chuck sheds a jaw but is unlikely to stop it. Also it serves to contain coolant spray spun off the chuck. As we don't use flood coolant this usually isn't an issue for us. As setting up for faceplate work doesn't use a chuck key, and the most hazardous zone is the face of the faceplate, with its spinning projecting clamps, with full access required for machining operations, which a guard would not cover, the consensus is that removing the guard is an acceptable risk.''<br />
<br />
=== Turning and Facing ===<br />
We are getting good results in aluminium, brass, and even steel using HSS cutting tools in quick-change tool holders, and the ~ 94 um/turn power feed. Unfortunately due to lack of rigidity in both the machine and smaller diameter parts, if you don't want the outer end to be over diameter, a light final cut and multiple 'spring' passes will probably be required.<br />
<br />
For aluminium, a sharp HSS tool and 0.5 mm (20 div) depth of cut gives good results with power feed for rapid stock removal. Its also easy maths as each cut takes ~ 1 mm off the diameter. Finish cuts should be much finer, 0.1 mm (4 div) is 'in the ballpark'.<br />
<br />
For steel, using carbide insert tooling, a 0.25 mm (10 div) depth of cut is more appropriate, and with pre-applied cutting oil, gives reasonable results with power feed if you use enough speed. The maths is not quite so easy as you are only taking 0.5 mm off the diameter per pass. Again, use finer finish cuts but try to plan your cuts so the final cut is still cutting, not smearing the surface!<br />
<br />
When facing or parting off, some skill is required to turn the cross-slide handwheel steadily to get a decent finish and to avoid shock-loading the tool tip. Increasing the spindle speed in one or more steps to keep up with the reducing diameter is advisable, but avoid speeds that cause resonances (resulting in chatter). When parting off, small through-hole parts may be caught on a thin rod chucked in the tailstock, and pre-positioned inside the work with its tip right up to the parting off position.<br />
<br />
==== Using the Steady Rests ====<br />
For the fixed steady rest, see Blondihacks' Lathe Skills #26 - How To Use a Steady Rest! [[#Youtube_Playlists_&_Videos|{below}]]<br />
<br />
Ours doesn't have ball bearing fingers, so a smooth surface on the work and adequate lubrication are essential. The thumbscrews can only tighten the fingers, so for small adjustments outwards you need to either slack off the clamping nuts or ease them slightly and use a drift against the back of the finger's slot. Once set, check the chuck still turns freely.<br />
<br />
The traveling steady rest needs to run on a machined surface, so at least for the first pass, must follow the tool, so its difficult to avoid using more compound slide overhang than is desirable. An initial surface should be cut next to the chuck or tailstock center before fitting the steady rest.<br />
<br />
Both are a PITA to fit - the fixed one has to have its clamping post inserted up through the bed, and the supplied spanner is useless near the headstock, and the travelling one's mounting holes on the saddle almost invariably need swarf picked out of them.<br />
<br />
==== Turning Between Centers ====<br />
<s>Using a MT3 to MT2 reducing sleeve, the MT2 dead center can be fitted in the spindle.</s> ''Currently the MT3 spindle taper is compromised.'' Alternatively, a soft center can be turned immediately before use in the three jaw chuck, but that must have its 60° point re-cut to concentric if the chuck is disturbed, and needs to be either large enough to bear on the chuck body, or must have a lip to bear on the end face of the jaws to take the axial thrust. Recutting the center is a PITA, as the compound angle must be set to 30° anticlockwise, then reset to a true 0° afterwards. Maybe a right-hand 30° end angle zero rake form tool is the answer, or use the carbide insert tool SSKCR0610H06 as a form tool with the toolpost rotated 15° anticlockwise.<br />
<br />
With the MT2 live center in the tailstock quill, this gives us a center either end of the work to hold it.<br />
<br />
We also need a drive dog similar to [https://littlemachineshop.com/products/product_view.php?ProductID=4473&category=1 this], and the corresponding drive post to bolt to the spindle nose. I have some 25mm bore thick wall iron pipe, which should do nicely. Lengths of the dog's straight tail and of the post TBD after I check how much the center protrudes. N.B. its recommended to tie the tail to the post to keep them in contact so they don't slam. ''Currently we will need to drive from the chuck jaws. Possibly use the exterior jaws with a short soft center gripped on the inside end and drive from the highest step.''<br />
<br />
=== Drilling ===<br />
Always start with a center drill so deflection of longer bits doesn't start the hole off-center. For larger bits (> 5 mm), first drill to the web size, then to final diameter. For a precision hole, drill slightly undersize and ream to final diameter. ''Supply your own reamers!''<br />
<br />
Caution: See note about the quill anti-rotation pin in section [[#Tailstock Quill|Tailstock Quill]] above.<br />
<br />
=== Boring ===<br />
Caution: As the spindle doesn't extend right through the headstock housing, if boring in a through hole, chips tend to fall out the back and tumble in the spindle bore till they fall into the change gears. To avoid this, one should plug the spindle bore with a wad of paper towel or rag and when cleaning up afterwards, use a rod to push it through towards the tailstock, with the chuck jaws (if fitted) wound clear of the spindle bore.<br />
<br />
A swivel bladed hole deburring tool (pale blue handle) can be found in the main room on the windowsill behind the drill press.<br />
<br />
A couple of boring jobs have been bodged with an awkwardly angled turning tool and achieving acceptable effective rake with enough clearance to reach deep enough into the hole has been problematic. I reviewed the tools we had and found none suitable for starting out in a 13mm bore, the max diameter we can (easily) drill. I therefore decided to buy a set of boring bars and make a holder for them. I had difficulty finding anything affordable under 10mm shank - the best low cost option was a [https://www.amazon.co.uk/dp/B07P5LGVBX set of nine 3/8" (9.525 mm) shank brazed carbide tipped boring bars], which would be close to the max capacity of the quick change boring bar holder - if we had one! Unfortunately this holder for our specific toolpost is difficult to find except in a toolpost bundle. Another annoyance is the variable tip height of the set, varying from 1.8 mm to 2.8 mm above the center of the shank.<br />
<br />
I therefore decided to make a boring bar holder of the [https://littlemachineshop.com/products/product_view.php?ProductID=1700 Littlemachineshop.com (USA) style] for use in the four way toolpost, as the additional rigidity will certainly help. Starting with a slightly over 50 mm length of 16 mm aluminium square bar and using the four jaw chuck , both ends were faced and an attempt was made to find its center and center drill it. It was then drilled out to ~9.8 mm after much drama due to blunt drills and drills that cut ~1mm oversize. Too big, but beggars cant be choosers as we didn't have a boring bar holder or a 3/8" reamer. Unfortunately the final hole ended up significantly off center. It was then chucked crossways and ~1 mm skimmed off its thickest side to gain clearance to allow it to be shimmed to height, then one side was slit lengthwise manually with a hacksaw.<br />
<br />
It was fitted to the for way toolpost and loaded with a booring bar, which clamped firmly. A 0.86 mm shim stack brought the tip of the largest boring bar almost spot on center height, with the difference easily accommodated by twisting the tool slightly. The three jaw chuck was then remounted, and a piece of iron pipe chucked for a test. It cuts well and leaves a decent surface finish.<br />
<br />
''The boring bar setup is a work in progress - talk to me before attempting to use them if you have a project that would benefit from boring..''<br />
<br />
ToDo: get something that can sharpen tools tipped with this grade of carbide - it needs some sort of diamond (or possibly CBN) wheel as green grit silicon carbide does little more than polish it. ''N.B. diamond wheels are rapidly eroded by grinding steel, so the supporting steel seat must be undercut with a regular grinding wheel before the diamond wheel can contact it.'' <br />
<br />
We'll also need 50 mm square sheet shims to fit under the toolpost to gain clearance in the toolpost above the tool or toolholder. A 2.4 mm shim would give us about the same above and below spindle center height, and we probably need a small selection of thinner ones.<br />
<br />
=== Thread Cutting ===<br />
The objective is to cut a thread that complies with the ISO metric thread profile. Our lathe is not currently equipped to cut non-metric threads, (with the exception of BA which have pitches based on metric threads of that era).<br />
<br />
[[File:ISO and UTS Thread Dimensions.svg|frame|center|Metric Thread Profile - from the geometry, H is ~86.6% of P]]<br />
<br />
Metric thread data - See 'Preferred Sizes' at: https://en.wikipedia.org/wiki/ISO_metric_screw_thread<br />
<br />
See "Mini Lathe User’s Guide" section '''Threading''' for general techniques *ONLY*, and above for change gears and threading dial setup.<br />
<br />
Amadeal specify the max. thread pitch as 2.5 mm. Any thread pitch greater than 1.5 nn requires the change gears to gear up. When gearing up it is desirable to distribute the ratio as evenly as possible over the two pairs of gears in the geartrain to avoid excessive tooth loading.<br />
<br />
==== External Threading ====<br />
Initially turn work to required Major Diameter, set up change gears and threading tool, touch off on the work, zero the top and cross slide dials, and do a 'scratch' pass to check the pitch. Back off the tool, return the carriage, and re-engage the half nuts on a valid dial line clear of the end of the thread then immediately stop the lathe, and hand turn the chuck till the tool tip is (hopefully) over the scratch to check the thread pickup. If all is good, return the carriage again, restart the lathe and start cutting your thread. <br />
<br />
Methods of doing so vary depending on the size of the thread and toughness of the metal, but straight-in plunge cutting is generally to be avoided as has the highest cutting forces, and does not reliably keep the carriage (and top-slide if set parallel to the work) loaded to avoid pitch errors due to backlash. <br />
<br />
If leaving the half-nuts engaged and reversing the lathe to return to the start of the thread for the next pass, its absolutely essential to back the tool out of the thread for the return pass as it will not follow the path of the cutting pass due to backlash in the geartrain, leadscrew mounts and half-nuts.<br />
<br />
==== Internal Threading ====<br />
''<nothing here yet>''<br />
<br />
== Cutting fluids ==<br />
=== Why bother? ===<br />
[https://youtu.be/mRuSYQ5Npek Watch this video] and contemplate what's actually happening to that thin ribbon of metal being removed. Most of the lathe's motor power is being turned into heat by internal friction in the chip being removed in the zone around the cutting edge, and surface friction at, and immediately behind the cutting edge, near-instantly heating the chip by up to several hundred degrees. Reducing the surface friction using a suitable cutting oil reduces the strain on the machine as a whole, and reduces workpiece and tool heating (and thus expansion) with consequent improvements in maximum usable feed and depth of cut, surface finish and accuracy. It also drastically increases the life of the cutting edge.<br />
<br />
=== Practicalities === <br />
We don't have a coolant system for the lathe and *really* don't want the maintenance hassles of using soluble cutting oil/coolant as if used infrequently its a PITA to keep recirculated high water content cutting fluids from going rancid and stinky, and they can also rust the ways, so even a total loss gravity feed system is problematic. Therefore if dry machining doesn't give a good enough finish, we tend to use oil applied topically, by hand to the work. <br />
<br />
* Hard brass is typically free-turning without oil, however some light oil for the final cut can improve surface finish, but with the disadvantage that it will increase loose chip buildup on the tool as hard brass typically forms short spalls or splinters rather than curly chips.<br />
<br />
* Many Aluminium alloys tend to be gummy, and Paraffin or other mineral spirits mixed with a little oil can help prevent the aluminum welding to the tool edge. WD40 will do at a pinch, but its messy to apply from a spray can.<br />
<br />
* Steel really needs *GOOD* cutting oil. Lard oil is the traditional choice for steel. If there are any objections to lard oil, we should bite the bullet and get some commercial dark high Sulphur cutting oil, but beware, many such oils use an additive package that includes lard oil.<br />
* Cast iron (except ductile) should be cut dry, as the carbon micro-inclusions self-lubricate it, and the carbide in the dust (primarily Cementite) are very abrasive, so tend to form a grinding compound if mixed with oil. <br />
<br />
I've sorted out an oil pot lid with a 1/2" brass collar soldered in to give a nice smooth sided hole, for ease of use and to minimize the risk of spills when using a brush to apply cutting oils, and got some dirt-cheap brushes. It fits Shippam's paste (and similar own-brand spread) jars and I've found several jars and ordinary lids to seal them for storage. Unfortunately it isn't the easiest to get this type of jars' lids back on square so they seal properly, and if you over-tighten them and there's a temperature change, they can be a total <expletive> to reopen. Using the rubberised handles of a large pair of pliers to grip the jar lid just above its rim is the best option, and avoids damaging the lids.<br />
<br />
''N.B. For the smaller brushes, the glue holding the bristles in is attacked by paraffin. To prevent loss of bristles, crimp the aluminium ferrule of each new brush of this type before use.''<br />
<br />
We have, in labelled jars:<br />
<br />
* Sulphurised Lard oil thinned with paraffin. Best choice for heavy cuts and threading in steel but stinky.<br />
* Lard oil thinned with paraffin. Good for steel and acceptable for softer copper alloys<br />
* Paraffin with a trace of light oil. Good for aluminium, and can help prevent squealing chatter on finish cuts in brass.<br />
<br />
I've also got some paraffin wax (in the form of a stubby candle), which can be applied lightly (under power) to brass and aluminium stock especially on the finish pass. It makes less mess than oil but unfortunately tends to build up on the tool tip, making it difficult to 'work by eye' without frequent pauses to clean the tool tip.<br />
<br />
We've also got a tin of [https://www.rocol.com/products/rtd-compound Rocol RTD cutting compound], which is a thick paste. Its highly recommended for drilling and tapping steel (in the drill press or by hand), but as a paste, is less useful for general lathe work unless thinned to a fluid consistency, e.g. with paraffin or white spirits. OTOH its certainly worth trying for high speed facing steel as it is less likely to get flung off.<br />
<br />
== Cleaning and Maintenance ==<br />
Swarf is a significant cut hazard to the operator, especially stringy swarf from cutting steel. Never touch it bare-handed - always use a tool e.g. a brush, or a hook, or needle nose pliers for grabbing long swarf.<br />
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* After use, brush all swarf off the toolholder, compound and cross slide etc. ways and leadscrew. Ian B has blocked off the opening at the headstock end of the rear splashguard (to try to keep swarf out of the motor), so one must sweep the swarf towards the open tailstock end and catch it in a dustpan or similar. Preferably, also thoroughly clean out the chip tray under the lathe, but at least sweep out visible swarf.<br />
* Wipe up any cutting fluid residue and re-lubricate affected sliding surfaces with way oil.<br />
* Do not solvent clean the chuck guard, as it will make the plastic brittle, or even craze it. Water with a little detergent is permissible for cleaning it, with the guard totally removed from the lathe.<br />
<br />
Before engaging the half-nuts for power feed/threading, check the leadscrew is clean! ''Best cleaned under power, with a toothbrush.'' <br />
<br />
'''Caution:''' The traverse gears behind the carriage handwheel are in an open-backed housing and tend to become packed with swarf! Swarf buildup here will result in jerky carriage movement. Clean out as much as you can with a toothbrush ...<br />
<br />
===Lack of lubrication and/or swarf or dirt build-up can be disastrous===<br />
* If using the change gears/power feed, lack of lubrication of the B-C stub shaft center pin or either leadscrew end bearing can result in seizure and immediate destruction of one or more gears in the gear train or worse. <br />
* Small pieces of swarf can get between the saddle and ways, or into the slides degrading accuracy, possibly permanently if hard swarf scores them, or jamming them. The carriage handwheel gears behind the apron are notorious for accumulating swarf, and swarf buildup on the leadscrew can prevent the half-nuts engaging properly, resulting in scrapped work, and possibly stripped half-nuts. <br />
* Metal swarf can get into the motor (''though Ian B has modified the rear chip catcher to reduce the risk)'' or into the control box via the leadscrew, and short-circuit stuff. At best it will blow the fuse and need a strip-down to clean it out, at worst it may require a replacement [https://www.amadeal.co.uk/acatalog/Speed-Control-Circuit-Board--12amp-AMA_SP_CJ18_SCB12.html#SID=12 speed controller] ''(currently £96)'' and/or [https://www.amadeal.co.uk/acatalog/550W-motor-for-CJ18A-Mini-Lathe-467.html#SID=240 motor] ''(currently £105)'' and possibly other electrical parts. We should probably fit a [https://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C3-Mini-Lathe-Spares/C3-256-Leadscrew-Grommet-Dustproof-Cover C3-256 Leadscrew Grommet] to keep swarf out of the control box, as it tends to drop onto the 'Filter' board which is mounted horizontally, below the leadscrew.<br />
* Grit from grinding, sanding etc. forms a grinding paste with the way oil, and will rapidly wear out the ways, saddle and slides. Keep grit off at all costs e.g. by covering the ways and slides during grinding/sanding operations, and if there's any chance grit has gotten where it shouldn't, clean and re-lubricate *BEFORE* moving the carriage or slides, then move the carriage and slides, wipe down where they were with a clean paper towel and check there's no remaining traces of dirt other than clean way oil on the paper towel. If it doesn't come clean when you re-lubricate and move it again, a full strip down may be required to solvent clean and relubricate the precision sliding surfaces.<br />
* Although a metalworking lathe *can* be used to turn hardwood, wood dust and small chips are extremely pernicious, as they get everywhere, even clinging to clean surfaces, are abrasive due to their silica content, and are hygroscopic, promoting rust. An even more thorough clean-up than after using abrasives is needed, immediately afterwards. Oily wood dust and fine wood chips in significant quantities are a fire hazard, even in the trash bin.<br />
<br />
===Lubrication===<br />
See section: "Lubrication" in LittleMachineShop.com "Mini Lathe User’s Guide" [[Ian_M's_Lathe_Notes#Manuals|(below)]]. As we usually only open two nights a week, in the table on page 16, Daily lubrication becomes Weekly and Weekly becomes Monthly.<br />
<br />
===General Maintenance===<br />
* The grubscrews holding the cross-slide and compound slide dials tend to loosen due to vibration and use of the dials. Keep them snugged up, but not so tight the dials cant be set without an Allen key.<br />
<br />
* The screws holding the cross-slide nut tend to work loose due to vibration. Crank the handle to and fro through the backlash and visually check there is no movement of the screw heads in their holes. If there is, see the [[#Excessive_cross-slide_backlash|notes below]].<br />
<br />
===Removing the Carriage===<br />
Its possible to remove the carriage from the bed for cleaning etc. without dismantling it. The only stop to its motion is the righthand leadscrew bearing.<br />
<br />
Start by removing the tailstock. Crank the carriage to the tailstock end then remove the leadscrew bearing (two screws and a nyloc nut on the leadscrew end). With the half-nuts open, hold the leadscrew centered in them and crank the carriage off the end of its rack, then slide it off the end of the bed.<br />
<br />
Refitting is the reverse of removal, except (if its gibs are correctly adjusted) the carriage will be very tight on the end of the bed ways so may be difficult to work onto the ways without a stack of blocks of wood or similar to support it at exactly the right height. The righthand leadscrew bearing must be refitted with the carriage as close as possible to it and the half-nuts firmly closed to support the leadscrew at the correct height to hold it in alignment while the screws are being tightened. The nyloc nut controls leadscrew end-play. Fully tighten it then back it off slightly till the leadscrew turns freely with its change gear removed.<br />
<br />
If the Apron has been off, refit it with the screws no more than lightly finger tight and only finally tighten them after checking lead screw engagement at both ends of the carriage travel and that the rack and pinion operates smoothly over the full travel.<br />
<br />
== Issues and Annoyances ==<br />
As of September 2023 - mostly resolved, apart from the spindle bearings and runout, the lathe is in better condition than it has been for a number of years.<br />
<br />
===Four Jaw Chuck has two jaws too tight===<br />
Fixed 27/10/2023: The grooves in the opposite sides of the jaws that run in the chuck slots were slightly out of true, and the rails either side of the slots were slightly too thick towards the center. Due to the difficulty of seeing the high spots, after cleaning up and deburring the jaws didn't do enough to ease them, I decided to grind the top of the rails where they were binding. Several repetitions of spotting, grinding then diamond filing the high spots has eased them enough. I cleaned everything, greased the jaw slides and screws, and refitted the studs so the chuck is now fit for service. <s>Two of the chuck jaws are tight in their slots, making precise adjustment difficult due to lack of 'feel'. Moving the jaws round the slots shows the problem follows the jaw not the slot, and stoning various edges hasn't helped so it seems that the affected jaws are slightly oversize. Need Engineer's spotting blue to determine which of the sliding surfaces is binding, so we can see what needs scraping/stoning/grinding to fix them</s><br />
<br />
''N.B. Don't move the jaws to a different slot - the formerly tight jaws *must* stay in the slots furthest from the makers mark.''<br />
<br />
===Excessive Runout===<br />
Mostly fixed 24/10/2022: I ground the chuck seating surface of the spindle nose (outside lip) to under half a thou runout. This also cleaned up several burrs. It would be possible to do better, but that would need good spindle bearings, and a more rigid toolpost grinder mount.<br />
<br />
Our spindle nose was damaged years ago by a person with little mechanical aptitude (who shall remain nameless) beating it up with a hammer mushrooming the spindle nose. We are getting several thousandths runout at the end of the MT3 bore, a MT3 to MT2 reducer sleeve in it runs visibly out of true, as does the spindle nose flange. When you put a chuck on it, the runout is magnified by the distance from the spindle nose. Ideally we would replace the spindle when we change the bearings but its £52 [https://www.amadeal.co.uk/acatalog/4-Spindle-Upgrade-Real-Bull-Mini-lathe-CJ18-series-AMA_SP_CJ18_003RB.html#SID=9 from Amadeal] and money is tight. It may well require more work after the bearing upgrade. Once good bearings are in, if we can borrow a decent MT3 arbour as a reference, we should consider skimming the bore.<br />
<br />
===Spindle bearings===<br />
* The spindle bearings appear to be close to worn out. They are notably noisy when running, and there appears to be more slop in the spindle than is desirable. We have some ideas for possible replacement/upgrade, but it requires a major teardown.<br />
<br />
: The original bearings are allegedly 6206-2RS or 6206-ZZ deep groove ball bearings - 2RS codes rubber seals both sides and ZZ codes metal shields. Although the deep groove gives reasonable ability to withstand axial loads, the bearing balls point contact means they are vulnerable to [https://en.wikipedia.org/wiki/Brinelling brinelling] due to shock loading. The jammed on three jaw chuck didn't help this, as before we skimmed the spindle nose lip, it had to be driven off using a bar through the spindle bore, shock loading the bearings every time. Also even a minor 'crash' could have brinelled them due to eccentric shock loading, and the lathe has previously been crashed badly enough to need drive gear replacement. There are also issues with the 'approved' method of spindle and bearing removal from the headstock brinelling them, even if you don't abuse the spindle nose with a hammer!<br />
<br />
: A possible replacement is 30206 tapered roller bearings. The new bearings are slightly thicker so the plastic spindle spacer (15) needs to be machined to length to get the 45 tooth spur gear that drives the change gears laterally aligned with the tumbler gears. If a temporary replacement (3D printed?) is fitted, the lathe can be run (without power feed capability) so this can be done on the lathe after fitting the new bearings. As tapered roller bearings have line contact, they are significantly more resistant to brinelling.<br />
<br />
: ''See [[Talk:Ian_M%27s_Lathe_Notes]] for notes, links etc. for this upgrade.''<br />
<br />
===Motor stuttering===<br />
* Fixed 21/09/2023: The motor was running very erratically and it was very difficult to set a speed. Several loose connections were found in the control box, mostly loose female spades to the motor controller board, but also a dry jointed braking resistor on the 'Filter' board, and an inhibit wire completely off its terminal on the forward/reverse switch, making intermittent contact. After tightening and/or remaking all affected connections, it was much improved but still not right below 300 RPM. The remaining issues were due to poor wiper contact in the speed control pot, and stripping it, cleaning the track and contact ring and re-tensioning the contacts resulted in the motor now running smoothly over the full speed range. The speed is slow to settle, and while part of that is probably the lag in the digital tach, I suspect that the KBIC motor speed controller isn't properly tuned as it was (allegedly) previously replaced.<br />
<br />
===Drive belt slipping===<br />
* Fixed 28/9/2022: During testing the motor after the above issue, it was noted that the chuck could be stalled, slipping the drive belt, with not much torque. The drive belt was determined to be loose and a bit worn, but still in acceptable condition. <br />
<br />
: Access for servicing the belt requires removing the control box ''(2 spades to ZVR switch disconnect the supply, speed sensor and motor simply unplug from the 'filter board')'', the motor cover, chuck guard switch assembly + wiring cover, the change gear 'A' (drive) shaft carrier assembly, and the tumbler gear assembly. See https://youtu.be/EkxlIz01BdA for disassembly/reassembly, though on our lathe, the speed encoder ring on the spindle prevents the belt cover from being fully removed without disturbing the spindle nuts. There is enough room to work with it loose, but still trapped by the encoder ring. Also, unlike the video, if the 'jack' screws under the headstock are correctly adjusted, and the studs aren't excessively bent, there is no need to make custom studs. <br />
<br />
: It turns out that our lathe was missing the M6 hex headed jack screws that press the motor down to resist the belt tension, and the motor had cocked out of position at a severe angle. I know Ian B had had considerable trouble adjusting it after the motor fault back in October 2022, and I believe it had been getting slowly worse ever since. The jack screws were probably mistaken for headstock fixing bolts during disassembly after the crash that resulted in the metal Hi/Lo gears being fitted, then lost. The penny washers on the studs had dished, so I turned them over and backed them up with smaller washers and switched to nyloc nuts so they cant back off due to vibration. N.B. there is a packing washer on the motor side on one of the studs, presumably so the shaft is true to the ways. Adjusting the motor is awkward to say the least. One has to slack the stud nuts off a lot, pry under its rear end to lift it enough to be parallel to the ways, snug the stud nuts, check alignment, then set the jack screws and their lock nuts to hold it there, and finally tighten the stud nuts. <br />
<br />
: Tension: According to Sieg, it should be possible to twist the belt 90° mid span with a light finger grip. Other sources say 1/32" - 3/32" deflection mid span with light finger pressure.<br />
<br />
===Speed display blanking===<br />
* The speed display has been intermittent, blanking and flashing 8888 and 0 at certain speeds for as long as I have been using the lathe. Finally on 18/07/2022 it failed completely, with no display. I removed the display module and bench tested it - the pins are labelled 5V GND PL PE, PE is frame ground and PL is a TTL level pulse from the speed sensor - confirming that it was in good working order. My suspicions then turned to its power supply on the 'Filter' board. With both the sensor and display unplugged, the 5V rail was found to have a only a couple of volts, but the unreg DC was 17V and stable. Replacing the 78L05 5V regulator restored the 5V rail and normal operation.<br />
<br />
: ''I conclude its been failing for a while with high load current due to speeds with more lit segments causing it to drop out, resetting the speed display, causing it to blank, lowering the current enough for the regulator to recover, then the display MCU lamp tests (8888) then re-acquires the speed, repeating ad-nauseum till the speed is changed. I don't like the design as the high input voltage results in excessive dissipation.'' <br />
<br />
: ''ToDo: Bench test display to measure its worst case current consumption, then fit an appropriate dropper resistor to reduce the 78L05 dissipation.''<br />
<br />
===Quill spinning when drilling===<br />
* The quill was tending to spin while drilling because its anti-rotation pin (a M5 dog tip setscrew) was sheered. I've removed the debris, aligned the scale with the top of the tailstock and fitted a longer M5 dog-tip setscrew to replace it, with a nut to lock it at the correct height. N.B. the pin isn't that 'meaty' so if using big drills in tough metals, to prevent shearing it, it should be backed out so the quill can be turned by hand and unwanted rotation controlled by being quick with the quill lock if it starts to spin, or even using a close fitting rod in one of the chuck key holes with plastic tube over it to protect the ways. <br />
: ''If the screw sheers again, the quill will need to be removed and the tailstock taken off the lathe so the sheered tip can be shaken out, and if the setscrew is difficult to remove it probably means the threads are mangled where it sheered. Try driving it right through with the quill out.''<br />
<br />
===Sloppy quick change toolpost locking mechanism===<br />
* Once the dovetail clamp screw was slackened, there was nothing preventing the dovetail twisting or cocking significantly, and friction with the toolholder made it tend to do so, making toolholder insertion and removal more difficult unless the clamping screw was backed off excessively. I added a compression spring around the clamp screw inside the toolpost to push the dovetail outwards so it mostly retains alignment when open, allowing toolholders to slide on or off cleanly with far less screw slackening.<br />
<br />
===Leadscrew rubbing===<br />
* The leadscrew shaft is rubbing on the insulating separator inside the control box. Unfortunately the corner of the relay on the Filter Control Board (#160) doesn't allow enough clearance. Although the friction isn't much of a problem at high reduction ratios, e.g. 16:1 power feed, it increases the stress on the change gear train, and may be problematic when threading at feeds above 1:1. ''Possibly pack out the control box mountings by a couple of mm.'' <br />
<br />
===High/Low lever backwards!===<br />
* The high-low drive gear selector behind the headstock is incorrectly labelled and differs from the manual: low gear (which we normally use) is with the lever towards the tailstock. ''I suspect that the gears in the headstock were refitted the wrong way round when it was upgraded to metal gears.''<br />
<br />
: ''ToDo: Get it reassembled the right way round during the spindle bearing upgrade!''<br />
<br />
===Carriage lock fouls top slide===<br />
* The T handscrew has been replaced with a M5 hex headed bolt, to permit access when the top slide is over it. An 1/4" drive 8mm socket is usually left on it, but needs to be removed when the full cross slide travel is needed. The small (4 jaw) chuck key is near enough 1/4" to use for it. If you need to (un)lock it while the compound is over it, you'll need an 8mm spanner. ''The [https://www.amadeal.co.uk/acatalog/Mini-Lathe-Carriage-Lock-463.html Amadeal lock screw] is in the spares tin as it was too high and fouled the compound slide.''<br />
<br />
===Tailstock locking lever loose===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock - See full image for key to screws]]<br />
* Diagnosed and fixed 10/1/2023 - In the base of the upper section of the tailstock, there are two dog tip set screws that engage with locating grooves in the counter-rotating shafts carrying the eccentric locking cams. They'd backed off, probably due to vibration. They need to be tightened till they bottom out in the groove, making sure they are '''in''' the groove, backed off half a turn so the shafts can turn easily, and locked in place. There's no facility to do so, so reassemble with weak threadlocker. Unfortunately to get to them you have to remove the tailstock base slide, which is held on by the pressure of four adjusting grub screws, which all need backing off, and one socket headed bolt from underneath so full tailstock realignment is required after reassembly, which even for a rough alignment is tedious.<br />
: <s>The tailstock locking lever is loose and can be pulled out on its axis. It works OK when fully pushed home but needs investigating. ''I tightened the grub screw as the lever was coming off its shaft, but the whole shaft pushes/pulls in and out. It works OK fully pushed in, but it seems something that is meant to retain it has failed inside the tailstock base.</s><br />
<br />
===Gear alignment issues===<br />
* Change gear alignment is poor. I've currently got a gapped washer (to clear the key) packing out the A shaft so the gears line up, but this reduces the key's engagement so is problematic due to the high loading if the gears are set up for coarser threads. <s>Also I need to turn down some penny washers to slightly less than the root diameter of the metal 20T pinions, as gear retaining washers.</s> ''The gear retaining washers for A gear and B-C stub shaft are now done, turned down to slightly under 16 mm dia. Spares in the change gear tin. ToDo: The D (leadscrew) washer requires a larger center hole, so make two more with that hole.'' <br />
<br />
===Saddle gibs loose===<br />
* Fixed 11/04/2023: I took the apron off for access (and to clean the carriage handwheel gears), and found the front sheer plate screws were completely loose. I've snugged them up some and set the opposing grub screws and got a lot of the slop out. I've re-checked the front ones, and taken up the slop in the rear ones - Unfortunately it wasn't possible to get carriage movement to have an even 'feel' over its whole travel, and its noticeably tighter near the tailstock. If light hand pressure on the side of the unlocked carriage can cause movement (with the half-nuts open), its time to readjust them again, though it should be possible to move the carriage with a firm push. <s>The saddle gibs (actually the sheer plates) were too loose, to the point that engaging a slightly stiff threading dial could cause it to self-feed, an obvious crash hazard if working near the chuck or a step in the work.</s><br />
<br />
''N.B. the lefthand front opposing grubscrew is short, (fully recessed) and unlike the others does *NOT* have a locking nut as it must clear the traverse pinion. A wrap of PTFE tape provides enough friction to keep it in place, though possibly a bit of nylon fishing line down its hole would be better.''<br />
<br />
===Excessive cross-slide backlash===<br />
* ''Mostly Fixed <s>11/10/2022</s> again 07/11/2023:'' The cross-slide screw had excessive backlash (nearly three turns), possibly due to end float, which increases the risk of loosing track of the cut depth during threading operations. If you ended up off by a turn too far in, a crash was the most likely outcome.* 02/11/2023: The backlash is back up to one turn. I suspect the cross-slide screw nut mountings are working loose again.<br />
<br />
: So it turned out that the reason the cross-slide had nearly 3mm of backlash wasn't end float, it was loose cross-slide screw nut mountings. The nut has two socket headed cap screws pulling up, one either end, accessible from the top of the cross-slide, which control the tilt of the nut to take up backlash in the nut, and an opposing grub screw pressing down on the center of the nut to make it longitudinally rigid. I gambled the cap screws weren't too far out and snugged up the grub screw, and that immediately took out over 95% of the backlash which is now down to 10 divisions or so, or 0.25 mm. Shimming the cross-slide screw collar should take out some of what's left and careful adjustment of the nut tilt should get that down to under 0.1mm.<br />
<br />
: 07/11/2023: When the problem recurred I investigated further . It is difficult to get the cross-slide nut aligned correctly as it must be at the same height as the screw which is constrained by the bearing surfaces in the bracket. With the cross-slide almost at the front limit of its travel, I removed the screw and set the nut as level as possible and visually centered in the bore, then re-fitted the bracket and screw, then adjusted the tilt till it turned freely through the backlash. I then tilted it up at the front till some drag was felt to minimise the backlash and tightened the screws to lock it in place balancing them to maintain the same feel as I tightened them. The result was 7 divisions of backlash, acceptable but not great. During normal turning operations, the load on the nut is tension on the front screw and pressure on the grubscrew, so if it slackens again due to vibration from chatter, odds are it will be the rear screw that's loosened. <br />
<br />
* Further reduction of backlash: https://youtu.be/Wu_tI29JL2Y?t=163 <br />
: Brass tinned with Pb-free solder to form a white metal bearing surface should work at least as well as the bronze used in the video. The shim washer needs to be 10 mm ID and ~14 mm OD. It isn't necessary to remove the lead screw from the cross slide, as the washer can be fitted in-situ with only the bracket removed. Its also possible to closely estimate the required washer thickness from the backlash - note the number of dial divisions of backlash, then strip down the dial and bracket and with the gibs tight enough to keep the cross-slide from moving, push and pull the screw to assess its end float. A dial indicator mounted on the cross slide probing the screw flange will give you the total end float. Subtract the end float from the backlash, than take off another thou (0.025 mm) for running clearance to get the washer thickness (assuming it seats fully in the recess). If after fitting it, snugging up the bracket screws makes the screw too stiff to turn, the washer is too thick - either make another one or try to lap it down.<br />
: TLDR: measure flange on cross-slide screw and depth of recess in cross-slide bracket (behind dial) and machine a shim washer to take up nearly all the difference.<br />
<br />
===3 Jaw chuck didn't mount properly===<br />
* Fixed 7/4/2023 by grinding the spindle nose lip. The three jaw chuck can now be installed and removed by hand with no hammering. A test bar in it now has only 2 thou runout (TIR) at the chuck.<br />
: <s>The three jaw chuck and the faceplate aren't seating properly on the spindle nose. Its too tight on the register diameter of the lip. This results in grossly excessive runout, and also makes this chuck and the faceplate a PITA to fit or remove.</s><br />
: ''The spindle nose had been abused with a hammer (before my time) which mushroomed it and may have brinelled its bearings. See '''Excessive Runout''' and '''Spindle bearings''' above.''<br />
<br />
== Manuals, Books and other resources ==<br />
=== Manuals ===<br />
The [https://wiki.richmondmakerlabs.uk/images/a/a3/Lathe_InductionNotes.pdf RML CJ18A Mini-Lathe Induction Notes]. Your mandatory Lathe Induction will cover most of this but its good to be able to refer back to it.<br />
<br />
Official [https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Amadeal CJ18A Manual], or paper copy (less complete) kept on shelf above lathe.<br />
<br />
The [https://www.chesterhobbystore.com/wp-content/uploads/2022/11/Conquest-Super-Lathe.pdf Conquest Super Lathe manual] is considerably better than the Amadeal manual and is for a near-identical machine.<br />
<br />
The [https://littlemachineshop.com/images/gallery/info/minilatheusersguide.pdf Mini Lathe User’s Guide] from LittleMachineShop.com is even more comprehensive, going into its usage in some detail, with a proper TOC, and covers both US and Metric versions of Realbull Mini-lathes. ''The only fly in the ointment is the threading section assumes a US lead screw so change gear selections and threading dial divisions will not be correct for our lathe.''<br />
<br />
[https://www.arceurotrade.co.uk/machineguides/C3-Mini-Lathe-Dismantling-and-Reassembly-Guide.pdf Sieg C3 Mini-lathe Dismantling and Reassembly Guide] "A picture story book to help you dismantle and reassemble your Sieg C3 Mini-Lathe" ''It is similar enough to ours to serve as a maintenance guide, except for the electronics, spindle drive and other headstock innards.<br />
<br />
The motor controller is a clone of a [https://acim.nidec.com/drives/kbelectronics/-/media/kbelectronics/documents/dc-drives/manuals/kbic_manual.ashx?la=en KBIC® SCR DC Motor Speed Control]<br />
<br />
=== Books ===<br />
'''Metal Turning on the Lathe''', by David A Clark, Crowood Metalworking Guides, ISBN-13: 978-1847975232 [https://www.amazon.co.uk/gp/product/B00E78RKIG Kindle Edition (£8.99)]. ''A 'free' epub can be googled for, *NOT* linked here due to dubious legality.''<br />
<br />
'''[https://archive.org/details/03screwcuttinginthelathe Screwcutting In The Lathe]''', by Martin Cleeve (a pen-name of Kenneth C Hart), Workshop Practice series #3, ISBN-13: 9780852428382<br />
<br />
'''[https://archive.org/details/15workholdinginthelathe Workholding in the Lathe]''', by 'Tubal Cain' (a pen-name of Tom Walsh), Workshop Practice series #15, Argus Books, ISBN-10: 0852429088<br />
<br />
'''[https://archive.org/details/20metalworkandmachininghintsandtips Metalwork and Machining Hints and Tips]''', by Ian Bradley, Workshop Practice series #20, ISBN-13: 9780852429471<br />
<br />
'''[https://archive.org/details/38toolandcuttersharpening Tool and Cutter Sharpening]''', by Harold Hall, Workshop Practice series #38, ISBN-13: 9781854862419<br />
<br />
'''[https://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpaperT204.pdf Cutting Fluids]''', by EC Bingham, NIST Tech. Paper No. 204, 1921<br />
<br />
=== WWW resources ===<br />
==== Mini-lathe Specific ====<br />
There's a *LOT* of mini-lathe info online. Notable sites include:<br />
* http://www.mini-lathe.com/ - A major Realbull/Sieg mini-lathe resource.<br />
* http://mikesworkshop.weebly.com/lathe-modifications.html - many mods including carriage DRO autostop, and variable speed leadscrew motor drive, cross-slide motor drive, etc. He also has a page with a bunch of accessories, toolholders etc. - http://mikesworkshop.weebly.com/lathe-accessories-and-tooling.html<br />
* http://andysmachines.weebly.com/variable-speed-controls.html - Scroll down to the 'UPDATE' section for the schematic of a very similar SCR speed control board. It also has the schematic for an earlier version of the Auxiliary Control Board (aka: 'Filter' board).<br />
<br />
==== Forums ====<br />
''with publicly accessible archives''<br />
* https://groups.io/g/7x12MiniLathe - Mini-lathe specific, active<br />
* https://www.hobby-machinist.com/forums/mini-lathe-mini-mill-information.220/ - active<br />
==== Youtube Playlists & Videos ====<br />
* Blondihacks: [https://www.youtube.com/playlist?list=PLY67-4BrEae9Ad91LPRIhcLJM9fO-HJyN Lathe Skills] (playlist) - "This is an educational series to help you learn to use your metal lathe. Watch them in order for best results! Satisfaction not guaranteed, especially if you're a cranky sort of person."<br />
* Frank Hoose (Minilathe.com) has a couple of relevant Youtube playlists:<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn7ON0jGM5UbM-KZDT56MOIp Mini Lathe Operations]<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn4nGRZaVq3wTOlvZNOmdAZ2 Mini Lathe Overview]<br />
<br />
==== General Machining ====<br />
* https://www.machiningdoctor.com/ - "THE #1 MACHINING TECHNICAL HUB"<br />
<br />
==Projects==<br />
[[File:VESA mount.jpg|thumb|Machined VESA mounting plate (left) and plate from Dell monitor stand it must match (right). The translucent washer shows the size of the original center hole.]]<br />
* My first faceplate project was boring out the center hole in a VESA mounting plate to adapt it to fit onto a surplus Dell 1708FP monitor stand. The part was centered using the tailstock dead center engaging with its original center hole. I clamped the part with studs and penny washers on the driving side of two opposite corners, with cap screws in the next slot round to trap the corners under the clamping washers, then withdrew the tailstock and dead center. After machining out the bore, I used the tip of the tool, rotating the chuck by hand, to scribe a circle for laying out the bolt holes. I finished off laying out and drilling the bolt and locating holes by hand at home, fitted it to the stand, and mounted the 2nd hand LG 24" widescreen monitor.<br />
<br />
* Another ultimately unsuccessful project was fly cutting aluminum flat bar to thickness to make custom shims for the set of carbide insert tools, for the four way toolpost. The 8 mm shank tools need ~2.5 mm shim stacks, and the 6 mm shank tools need ~4.5 mm shim stacks. Ideally I'd machine single shims, but the only stock I've got handy cleans up to only 3.2mm, and some fine shimming may be needed to fine-tune the tool height.<br />
<br />
: After sorting out the clamps so they were no longer twisting the aluminum flat bar stock, and switching to the short 45° turning SCMT06204 insert tool in the four way toolpost, to improve rigidity and get a well controlled tip radius, the finish was much improved. I'm still having problems getting an even thickness and am getting approx. 0.05mm variation, I suspect due to the aluminium bar stock distorting due to internal stresses as its surface is cut away. ''ToDo: try supergluing the stock to the faceplate before clamping to further reduce chatter and stop the warping.''<br />
: Looking back on this project a year later, its fairly obvious that the thickness variation was probably due to faceplate surface runout due to the damaged spindle nose.<br />
<br />
* Raphael has been working on a steel rocket nozzle with some assistance from myself. We have set up the rough cut chunk of ~ 50mm steel bar, faced both ends (to 50mm length) and turned the OD to 49mm to clean it up. Its going to need through drilling, probably some boring, and quite a bit of detail work on the OD. It will then need to be transferred to a jig in the drill press vice to allow a pattern of angled traverse holes to be drilled with acceptable accuracy.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_Lathe_Notes&diff=17584Ian M's Lathe Notes2023-11-15T00:51:16Z<p>IanM: /* Shimming */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br />
<br />
''Currently these notes are semi-organized and non-authoritative. As I become more experienced with the RML CJ18A mini-lathe, I'm cleaning up, extending and reorganising them. Some lathe operating experience is assumed. If in doubt, '''*ASK*''' me, Andy H<sup>*</sup> , Jonathan H or another experienced minilathe operator!<br />
<br />
''* Andy H should be asked (for an authoritative answer) any questions involving RML usage policies or acquiring tooling or materials through RML.''<br />
<br />
== The Lathe ==<br />
Our Facilities page [[Facilities#Lathe|has]]:<br />
<blockquote><br />
'''Lathe'''<br />
[[File: Lathe2.jpg |200px|right | Lathe]]<br />
In the kitchen. <br />
<br />
Marked as a CJ18A Mini-Lathe from [[https://www.amadeal.co.uk/acatalog/CJ18A-Mini-Lathe-7x14-Machine-100mm-3jaw-Metric-With-Metal-Gears-AMA_LA_CJ18_M_3_MGRB.html Amadeal]]<br />
[[https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Manual]] <br />
<br />
[[Media:Lathe InductionNotes.pdf| Induction Document]]<br />
<br />
Possible upgrades:<br />
*https://www.youtube.com/watch?v=GwT-JQLbNPA<br />
<br />
''Please do not use the lathe until you have received induction'' <br />
<br clear=all><br />
</blockquote><br />
Its a Chinese import 7x14 mini-lathe. The 7x14 refers to the maximum diameter and length of work, in inches and is only a theoretical measure of the working envelope as you loose length to the chuck + any tailstock tooling, and the diameter is over the bed, not the cross-slide. See actual specifications below. <br />
<br />
Most if not all Chinese 7x10 to 7x16 mini-lathes seem to be remarkably similar (not uncommon with Chinese products due to [https://www.bunniestudios.com/blog/?p=284 Shanzhai (山寨)] )<br />
and the OEM of our Amadeal CJ18A Mini-Lathe was probably [https://www.made-in-china.com/showroom/cheap-lathe Yangzhou Realbull Machinery Co. Ltd]. Very similar lathes are also made by [https://www.siegind.com/lathe-machine.html Sieg], but their lathes tend to be slightly less sophisticated than the equivalent Realbull models.<br />
<br />
''N.B. Many Sieg parts are known to have slight but critical differences from Realbull parts, so '''DON'T''' order Sieg spares for a Realbull lathe!<br />
<br />
== Key Specifications ==<br />
Amadeal says the CJ18A Mini-Lathe is a 7x14 model with:<br />
<blockquote><br />
* Power 550 W<br />
* Distance between centres : 350 mm<br />
* Swing Over Bed: 180 mm<br />
* Swing Over Cross Slide: 110 mm<br />
* Taper: MT3<br />
* Tailstock Taper: MT2<br />
* Chuck diameter: 100 mm<br />
* Spindle Speed: 50 - 2500 rpm ''(with digital readout)''<br />
* Spindle Bore: 20 mm<br />
* Cross slide Travel: 65 mm<br />
* Range of Metric Threads: 0.5 - 2.5mm.<br />
</blockquote><br />
* The lead screw is metric, pitch 1.5 mm.<br />
* The spindle center is 90.6 mm above the flat of the bed (measured).<br />
<br />
Even though the compound and cross slide handwheels appear to be calibrated in thousandths of an inch, as ours is a metric machine, they only approximate that. One turn of a slide handwheel is 1mm advance, and they have 40 divisions, so each division is 0.025 mm, (approx. 0.984 [https://en.wikipedia.org/wiki/Thousandth_of_an_inch thou]). Similarly, the tailstock quill advances 1.25 mm per handwheel turn, which has 50 division dial, giving the same 0.025 mm divisions, but only 4 turns per 5 mm. The carriage handwheel is awkward - it moves approx. 19.2 mm per turn, and doesn't have a dial scale.<br />
<br />
== Notable Accessories ==<br />
We have:<br />
* [https://www.amadeal.co.uk/acatalog/160mm-Face-Plate-for-the-4-Mini-lathe-AMA_AC_CJ18A_FP160RB.html#SID=129 160 mm (6 1/4") Faceplate]<br />
* 100 mm (4") three jaw self-centering chuck (OEM standard) 22.5mm bore, with inside and outside jaw sets<br />
* 100 mm (4") four jaw (independent) chuck with reversible jaws (8 TPI screws)<br />
* Tailstock drill chuck (max. 13 mm dia.)<br />
* Live center for tailstock (+ OEM fixed center) <br />
* Four way Tool Post (OEM Standard)<br />
* [https://www.amadeal.co.uk/acatalog/Quick_Change_Tool_Post_for_the_mini-lathe.html Quick Change Tool Post] + 3 tool holders<br />
* [https://www.amadeal.co.uk/acatalog/Fixed-Steady-for-Mini-Lathes-AMA_AC_CJ18A_FSRB.html#SID=145 Fixed Steady Rest]<br />
* [https://www.amadeal.co.uk/acatalog/Travelling-Rest-for-Mini-Lathes-AMA_AC_CJ18_TSRB.html#SID=144 Travelling Steady Rest]<br />
<br />
''You'll find all of the above on the shelf above the lathe, with the accessories in the wooden box, apart from the steadies, which live next to it. Change gears, spare parts, and most cutting tool tips/blanks are in labelled white rectangular tins behind the lathe.''<br />
=== Measuring Tools ===<br />
We have:<br />
* Various dial indicators - the one with the adjustable magnetic base stand is the most convenient for most lathe setup work.<br />
* 25mm micrometer (in little grey case)<br />
* Grey case containing set of measurement tools including dial calipers, micrometer, steel rule (metric & inch), engineers square, and a fish-tail gauge<br />
<br />
''We currently lack''<br />
* ''A tool height setting gauge''<br />
<br />
=== Hand Tools ===<br />
Some common tools needed for normal use are kept with the lathe, in or attached to the wooden accessories box:<br />
* 2 mm Allen key - adjusting cross-slide and compound gibs<br />
* 4 mm Allen key - quick change toolholder tool clamping screws + height adjust, tightening dials<br />
* 5 mm Allen key - four way toolpost tool clamping screws, engaging/disengaging threading indicator<br />
* 6 mm Allen key - locking/unlocking quick change toolholder<br />
* 8 mm spanner - locking carriage when 8 mm socket can't be used, locking gib adjuster nuts <br />
* 13 mm spanner - changing chucks, locking steady rest jaws<br />
* Very long needle nose pliers - for grabbing swarf safely, holding one end of emery cloth safely so you can keep your fingers away from the jaws, and extricating small objects from awkward places.<br />
<br />
== Change Gears ==<br />
[[File:BC puller 1.jpg|thumb|Custom puller for B-C stub shaft]] [[File:BC puller 2.jpg|thumb|Pulling the B-C stub shaft]]<br />
See "Conquest Super Lathe" manual ([[#Manuals|below]]), section '''4.7 Change Gears''', PDF pages 28-29, but see below for mesh adjustment. The LittleMachineShop.com "Mini Lathe User’s Guide" (also below) section '''Threading''' gives a far better explanation, with pictures and diagrams, but its for a lathe with a US 1/16 inch pitch leadscrew, not a metric 1.5 mm pitch one like ours, so you *MUST* ignore all the tables in that section, replacing them with metric mini-lathe (with 1.5 mm pitch leadscrew) equivalents. <br />
<br />
We have the following tooth count gears: 20,20, 30, 35, 40,40, 45, 50,50, 60,60, 80,80<br />
which consist of the OEM power feed gears + the metric change gear set. Apart from the metal 20 tooth pinions, they are all plastic, probably Delrin if the molded in 'POM' marking can be trusted, but possibly plain Nylon 6, and are metric Module 1.<br />
<br />
If we wanted to add the capability to cut US/Imperial threads we'd need to buy additional 55, 57 and 65 tooth gears, and possibly a 21 tooth metal pinion.<br />
<br />
CGTK's [https://www.cgtk.co.uk/metalwork/calculators/changegears/minilathe?gears1=20,20,30,35,40,40,45&gears2=50,50,60,60,80,80&gears3= Change Gear Calculator] ''(link preloaded with our gear list)'' is useful if you don't want to calculate the ratios from first principles. Not all suggested combos will physically fit.<br />
<br />
* Take care *NOT* to loose the keys in the A and D shaft keyways - turn each shaft till the keyway is up before removing the gear. <br />
* The B and C gears are coupled by a hollow stub shaft (with an integral key), which is so tight in the gears it has to be pressed or driven out - I've made a puller just for this task, kept in the change gears tin.<br />
* The center of the B-C stub shaft *MUST* be lubricated where it runs on its pin on the change gear banjo bracket, with grease or heavy oil. ''Seizure of the stub shaft due to running dry is a frequent cause of catastrophic mini-lathe geartrain failures!''<br />
* Don't get oil on the change gears as it can cause plastic gears to crack. Only PTFE drylube or plastic compatible white grease should be used on their teeth. <br />
* Adjust the B-C pin position in the straight slot first to set the C to D gear mesh, tighten its nut, then swing the whole banjo about the D shaft boss to set the A to B mesh, and finally tighten the banjo clamping nut.<br />
* Check both gear meshes have running clearance by turning the chuck by hand enough to complete one full turn of the leadscrew, and by attempting to turn the intermediate gear(s) to assess backlash, If excessive resistance is felt or if there's significant backlash, readjust the gears. If you have difficulty judging the mesh, a strip of 80 gsm copier paper (approx. 0.1 mm thick) wound into the meshing teeth before tightening the stud or banjo will give appropriate clearance once removed. Once setup, check the gears run quietly under power.<br />
* If the sum of the tooth counts C+D is the same as for the ones you just removed and they were correctly meshed, you don't need to move the stub shaft pin. If A+B is <u>also</u> the same, you don't need to move the banjo. e.g. If it was set up for 16:1 reduction power feed, 1 mm (40:60 - 50:50) for M6 and 1.5 mm (e.g. 40:60:40) for M10 pitches can thus be achieved by only swapping gears. <br />
<br />
''The change gears, puller, etc. and a box spanner for the banjo nut are kept in a white rectangular tin behind the lathe.''<br />
<br />
=== Power Feed ===<br />
When used for turning with power feed, the change gears should be set for a 16:1 reduction (A:20 : B:80 - C:20 : D:80) using the pair of small metal 20 tooth pinions and the 80 tooth plastic gears (largest in set), for a feed of 0.09375 mm per turn (1.5 mm/16). Unless continuing your threading project the next session, please re-fit the 16:1 power feed set after threading so the power feed is ready for use. <br />
<br />
* *ALWAYS* leave the feed direction selector lever in its neutral (no feed) position, and the half-nuts open after use.<br />
* *ALWAYS* check the carriage lock is disengaged before engaging power feed. Unlock the carriage after use. <br />
<br />
=== Threading Dial ===<br />
The threading dial is an aid to re-engaging the half-nuts at the right moment so the tool will retrace its previous path cutting deeper, rather than offsetting axially some fraction of the thread pitch and ruining your work. Its based on the concept of the lowest integer multiples of the leadscrew and thread ''(being cut)'' pitches that exactly match, but for mechanical simplicity it only covers certain selected multiples of the leadscrew pitch.<br />
<br />
We have a choice of three pinion gears:<br />
{| class=wikitable<br />
|+ Threading dial Pinion Gears<br />
|-<br />
! Teeth !! Colour Dot !! Usable lines !! OD gear !! Dist. per turn<br />
|-<br />
| 14 || Red || 1,7 || 7.51 mm || 21 mm<br />
|-<br />
| 15 || Orange || 1,5,9 || 8.05 mm || 22.5 mm<br />
|-<br />
| 16 || Green || 1,4,7,10 || 8.37 mm || 24 mm (2 mm/div)<br />
|}<br />
They are now colour coded, with a paint dot on the gear end face ''(the only non-wear surface)''. The 16 tooth one is normally left on the lathe, but disengaged when not threading to minimise wear on the lead screw. The others are kept in the Change Gear tin.<br />
<br />
There's a threading dial 'pickup' calculator here: https://www.cgtk.co.uk/metalwork/calculators/threaddialindicator <br />
<br />
Initially select ''Lathe:'' '''Custom''', and enter the following below:<br />
* ''Units:'' '''Metric'''<br />
* ''Lead Screw Pitch (mm):'' '''1.5'''<br />
* ''Thread Dial Indicator Gear Teeth:'' '''16,15,14''' <br />
* ''Lines on Thread Dial Indicator:'' '''12''' <br />
* ''Line Marking:'' '''Every Line Numbered'''<br />
Note the teeth list is entered in reverse order so the resulting table highlights any required pinion changes.<br />
<br />
N.B. The dial is only friction clamped to the pinion by its center screw. If you have any reason to suspect it may not be properly aligned: <br />
# With the power off and the carriage unlocked, engage the feed direction lever upwards. You'll probably need to turn the chuck by hand to get it to engage.<br />
# If the threading indicator isn't already engaged, loosen the threading dial support block bolt, pivot the block to engage the pinion with the leadscrew and retighten the bolt.<br />
# Engage the half nuts, again turning the chuck by hand till they drop in. <br />
# Turn the chuck a couple of turns, top towards you to take up any backlash, then lock the carriage, taking care not to push it left while locking it.<br />
# Loosen the screw securing the dial to the pinion.<br />
# Align the '1' line of the dial with the index line, by rotating the dial clockwise, then retighten the screw.<br />
# Don't forget to disengage half-nuts and unlock the carriage!<br />
<br />
The above instructions should result in the half-nuts engaging cleanly when exactly on any valid line when threading towards the headstock. If it is required to thread away from the headstock, there will be a slight offset from the line due to backlash between the spindle gear and leadscrew, so engage slightly early.<br />
<br />
Changing the pinion:<br />
# Loosen the threading dial support block bolt and disengage from the leadscrew.<br />
# Undo dial center screw, and remove it and the dial, dropping the old pinion out the bottom.<br />
# Oil the shaft of the new pinion with a drop of light oil and insert it from below, gear end down.<br />
# Refit dial and screw.<br />
# Check the dial and pinion turn freely with minimal resistance.<br />
# Align as above.<br />
<br />
== Tailstock and Steadies ==<br />
These are mostly used to support long work ''(long with respect to its diameter)'' to improve rigidity, increasing accuracy and reducing chatter. The Tailstock quill is also used with a drill chuck for drilling.<br />
=== Tailstock ===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock base]]<br />
The tailstock can be offset to turn shallow tapers between centers. We don't currently have the accessories to turn between centers, namely <s>a MT3 dead center for the spindle, or</s> any drive dogs for the work. Also realigning the tailstock after turning a taper can be a PITA. The photo shows the tailstock adjusting screw locations ''(C - Lateral, and D - Skew)'' and the block on the baseplate they engage with. Adjustments can only take effect when the tailstock locking lever is eased to take the pressure off the baseplate. As we don't have a MT3 center, one has to turn a fresh point on a test workpiece for a rough tailstock alignment reference. Fine alignment, to avoid inadvertent taper turning, can be done by mounting a long precision ground bar between the chuck (or preferably a center in the spindle), and a dead center in the tailstock and sweeping it with a dial indicator on the carriage. Finally a test cut should be taken at either end of a bar between centers, and the diameters checked with a micrometer. Assuming the bed has previously been properly levelled and shimmed to take out twist ''(not the case at RML as we don't have it bolted down)'', any remaining difference in diameter will be double the tailstock offset, smaller at the tailstock being offset towards the front. Fine adjustment cant be achieved by jacking with the screws, its best to ease the adjusting screws, bump the tailstock into alignment then take up the screws again, checking the alignment is maintained when the tailstock is unlocked and relocked. There is no vertical adjustment, though shims can be added between the tailstock and its base.<br />
<br />
==== Tailstock Quill ====<br />
There is a metric/imperial scale on the top of the quill, read against the end of the tailstock, for depth measurement when drilling. The tailstock quill has a 1.25 mm pitch thread and a 50 division dial. Each division is therefore 0.025 mm, and it only takes 4 full turns of the handwheel to move the quill 5 mm. <br />
<br />
To eject MT2 taper tooling and centers from the tailstock, wind the quill all the way in.<br />
<br />
N.B. The quill anti-rotation pin (dog-tip setscrew + locking nut in top of tailstock near to the quill lock) is only M5. It will sheer if a large diameter drill jams in the work. Please back it out clear of its keyway if using large drills, and use alternative methods of preventing chuck rotation. To re-engage it, crank the quill out till you can see the keyway, align it with the screw and screw in the screw till it gently bottoms out, then back it off a quarter turn. Try twisting the quill to check its properly engaged, then tighten the locking nut gently to hold the screw in position clear of the bottom of the keyway.<br />
<br />
=== Steady Rests ===<br />
We have two, both with brass tips that must be kept lubricated during use.<br />
<br />
The fixed steady mounts on the ways, and is most useful when turning longer work that wont fit through the spindle bore. Adjustment is critical, and the surface the tips run on must be smooth and concentric, as any misalignment that forces the work off center will result in the work wobbling in the chuck, marring it, with a high risk of it becoming un-chucked, which can be dangerous at speed.<br />
<br />
The travelling steady mounts to the headstock side of the carriage to locally resist the deflection of thin long work, due to the cutting forces. It only has two tips, to resist climb, and deflection away from the tool, and requires readjustment after every cutting pass.<br />
<br />
== Tooling and Tool Holders ==<br />
'''Key dimensional data:'''<br />
* The quick change holders accept up to 10 mm shank tools. <br />
* The four way toolpost has 50 mm long sides, a seat width of 15 mm and can clamp tools of up to 5/8" (15.875 mm) shank ''(check this)'', but the slot base is only 10.4 mm below the spindle center so cannot be used with >10 mm shank tooling unless it has a dropped tip. Large tooling with a centered tip is also problematic as you run out of height above the shank when trying to shim to match the spindle center height. <br />
<br />
===Quick Change Toolpost===<br />
I've got the quick change toolpost and toolholders setup for mostly easy use. The three toolholders came with cantilever height setting arms which historically haven't been installed as the supplied fixing screws were too short. That's all now sorted out and a HSS RH turning tool and a HSS hand-ground grooving/parting-off tool are now mounted in two of the holders and set to height. The third is kept free for other tools. <br />
<br />
The quick change toolpost has been modified with a spring to press the dovetail clamp outwards and help stop it twisting or flopping about to ease toolholder fitting and removal. The dovetail clamp (socket headed screw on toolpost side opposite dovetail) feels a bit stiffer than before, but will take less than half a turn to go from open (with the toolholder lifting out or dropping in easily) to fully clamped. As there is so much less clearance in the open position you should no longer need to wiggle the toolholder while clamping it to get a consistent height. If the dovetail clamp ever gets misaligned, twist it straight by eye, slacken off a bit further than usual to get a toolholder on, clamp it to align the dovetail then release, reseat the toolholder and re-clamp to ensure its at its preset height. You cant adjust the height by 'jacking' with the height screw due to its offset leverage. Instead, back off the height screw and hold the toolholder at the desired height while locking the dovetail clamp, then adjust the height screw (and locking nut) to hold it there, then check it doesnt change height significantly when you unclamp and reclamp the dovetail. <br />
<br />
Unfortunately the OEM height setting screws foul the toolpost locking nut handle. Currently, if you need to swap toolposts you will have to first remove the quick-change tool holder from the post. There is enough nut handle swing to allow the quick change toolpost to be unclamped and rotated to fine set the tool angle without removing the toolholder. It also seems the mating surfaces may be slightly out of square, as if you rotate the toolpost 90° or 180°, the nut swing may be insufficient to re-clamp it without removing the toolholder to do so. Add a M10 washer under the locking nut if the handle ends up pointing in an undesirable direction! A thin M10 washer is kept with the toolpost collar for this purpose, and will shift the handle position by about a third of a turn. <br />
<br />
''ToDo: Make a taller nut of a similar pattern, to clear the height setting screws.''<br />
<br />
===Four Way Toolpost===<br />
The OEM four way toolpost is significantly more rigid than the quick change toolpost + holders because it has fewer and thicker parts and less overhang. Therefore the four way toolpost should be used when using carbide tooling. It requires shimming under the tool to set the tip height to the spindle center height - see below. The tool shanks are mostly significantly less than 15 mm wide, so need to be centered under its clamping screws, tempting as it is push the shank in for full side contact with the toolpost. If possible clamp the shank with all three screws not just two.<br />
<br />
==== Shimming ====<br />
We typically only mount up to two tools, and want maximum rigidity, so use 50 mm x 15 mm shims, (the full seat area), preferably with deburred edges and radiused corners so they aren't a hazard to the operator.<br />
<br />
We have pre-cut and marked shims of the following thicknesses: <br />
* 1x 3.23 mm, 2.42 mm, 1.56 mm, 0.32 mm, and 0.25 mm<br />
* 2x 1.00 mm, 0.77 mm, 0.12 mm, 0.11 mm, 0.10 mm and 0.05 mm<br />
* 4x 0.53 mm<br />
<br />
Our shims are mostly found materials (hence the awkward thicknesses) and are mostly a mixture of aluminium and steel, with a couple of GRP ones. The toolpost seat '''<u>must be absolutely clean</u>''' to avoid embedding debris in the aluminium or GRP shims, to get a consistent height and avoid tilting the tool - wipe it every time you change a tool! Put the thin shims at the bottom of the stack to avoid the tool shank edges creasing them. Shims are kept in a little yellow plastic box with a clear lid, near the carbide tools case.<br />
<br />
''ToDo:'' <br />
<br />
* ''Cut more shims neatly, mark them with their thickness.''<br />
* <s>''Do test cuts and start noting shim stack-ups for various tools.''</s><br />
* ''Organise shim storage!''<br />
<br />
=== HSS Tools ===<br />
[[File:Tool Bit Geometry.jpeg|thumb|Single point cutting tool geometry]]<br />
Our HSS tools are made from 8 mm square bar stock, hand-ground to tip profile in-house. See LittleMachineShop's [https://littlemachineshop.com/images/gallery/instructions/grindingtoolbits.pdf Grinding Tool Bits] notes. <br />
<br />
I've installed our usual HSS LH turning and parting off tools in two of the quick change holders and set the heights correctly. There are a couple of other HSS tools or tool blanks knocking about. Taking heavy cuts turning steel (even with good cutting oil) blunts HSS tools fairly quickly, which are time-consuming to re-sharpen nicely without a dedicated tool & cutter grinder with appropriate jigs. Its worth noting that the usual 'speeds & feeds' tables are commonly based on surface speeds expected to give a half hour (active cutting) tool life before resharpening.<br />
<br />
I touched up the LH turning tool by lapping on wet & dry (silicon carbide) paper on glass (Aka: [https://en.wikipedia.org/wiki/Scary_sharp 'Scary Sharp']) working upwards through the grits 200, 400, 600 and finally 1000, initially 'bluing' the surfaces to be lapped with a marker pen to see which areas needed taking down more. The end of the tool was significantly uneven so I touched that up freehand on the bench grinder to flatten it when it became apparent that 200 grit lapping wasn't cutting where it needed to. There was an existing micro-bevel on the leading side, which I kept. Finally I 'dubbed' the leading corner vertical edge on the 1000 grit to give it a very slight nose radius. A test cut on brass gave a very nice finish when turning.<br />
<br />
''Ian B has purchased some spare 8mm HSS tool blanks - talk to a lathe trainer if your proposed lathe work needs custom ground HSS tooling.'''<br />
<br />
=== Brazed Tungsten Carbide Tools ===<br />
Somewhat of a half-way house between hand ground HSS tooling and insert tooling with the disadvantages of both and some more besides - e.g. they are much harder to sharpen. So why do we bother? Some tool geometries would be awkward and tedious to hand grind, and Chinese import brazed carbide tooling is about half the price of similar HSS tooling, and far more readily available. Also, for space constrained tooling like boring bars, if you want carbide, for insert tooling, the size of the insert and its clamping seriously limits the minimum hole diameter you can work in. I have purchased a set of 3/8" shank brazed carbide tipped boring bars, but we currently cant sharpen them, due to lack of a diamond grinding wheel. <br />
<br />
=== Tungsten Carbide Insert Tools===<br />
Decoding ISO insert tooling part numbers: https://www.cutwel.co.uk/blog/learn-the-turning-tool-iso-code-system<br />
[[File:Carbide set.jpg|800px|thumb|left|Our set of Tungsten carbide insert lathe tools (before the new inserts were fitted)]]<br />
<br />
{| class=wikitable<br />
|+ Tools, left to right, (+ last across top):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| SSKCR0610H06 || 75° through boring || SCMT06204 || Long || 6 || 6.34 || ''4.33''<br />
|-<br />
| SSSCR0610H06 || 45° deep facing, internal chamfering || SCMT06204 || Long || 6 || 6.13 || ''4.58''<br />
|-<br />
| SWUCR0610H05 || 93° boring, deep facing || WCMT050308 || Long || 6 || 6.22 || ''4.48''<br />
|-<br />
| SWGCR0810E05 || 90° RH turning & facing || WCMT050308 || Short || 8 || 8.25 || '''2.45'''<br />
|-<br />
| SSSCR0610E06 || 45° turning, chamfering || SCMT06204 || Short || 8 || 8.75 || ''1.93''<br />
|-<br />
| SSBCR0610E06 || 75° RH turning, chamfering || SCMT06204 || Short || 8 || 8.72 || ''1.98''<br />
|-<br />
| LW0810R-04 || 60° external threading || JCL15-120 || Short || 8 || 7.44 * || ''3.28''<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || 8.23 || ''2.5 ?''<br />
|-<br />
| LN0813R-04 || 60° internal threading || JCL15-120 || Long || 7.95 || 7.44 * || ''3.28''<br />
|}<br />
<br />
{| class=wikitable<br />
|+ More Tools, (loose in tin):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || ~8.5 (not in use) ||<br />
|-<br />
| [https://www.glanze.co.uk/product/glanze-12-mm-60-degree-metric-internal-threading-tool/ Glanse SIR0012K11] || 60° internal threading bar || 11IRA60 || Long || 12 dia || ??? || ???<br />
|}<br />
''Shim stack heights in bold are tested, in italic are only calculated.'' ''Tip heights marked * are with new JCL15-120I inserts. The single remaining plain JCL15-120 insert has a slightly higher tip height.''<br />
<br />
Carbide tooling typically requires two to three times more speed than HSS and at least a couple of 'thou' depth of cut for best results.<br />
<br />
Chatter can rapidly kill carbide tooling by chipping the cutting edge. To improve rigidity and reduce the risk of chatter, the cross-slide and compound gib screws need to be well adjusted so there is minimal play in the slides, tool stick-out should be minimised, the four way toolpost should be kept over the cross-slide, and the work should be kept close to the chuck (or otherwise supported by tailstock or steady rest) to avoid excessive deflection.<br />
<br />
Thermal shock is almost instant death to carbide, and when dry cutting the insert tip can run very hot, so do not add extra cutting fluid manually during the cut. Pre-apply what you need, evenly, before starting the cut.<br />
<br />
Parting off or facing to center is high risk - if the tool tip is even slightly below center or if tool or work deflection takes it below center, the work will tend to climb over the tool tip as the cut approaches center, breaking the insert. To avoid this, the tool should be shimmed slightly above center, sufficient to allow for work and tool deflection, and unless very close to the chuck, a steady should be used. Its often preferable to part to a couple of mm dia. remaining then stop and saw through the remainder. Parting off hollow parts is much lower risk.<br />
<br />
Further investigation of the Tungsten carbide insert tool height situation is not encouraging - the so-called 'set' in question does not have a consistent tip height ''(see above table)''! In a real set, the insert seats *should* be machined allowing for the insert thickness to bring all the cutting edges to the same height with respect to the shank underside. However if you place them tip to tip on a table its easy to see there is considerable height variation, so they need to be individually shimmed (or at best, one machined shim will only be right for two or three tools). At this time we don't have dedicated shim stacks for each tool.<br />
<br />
A 2.42 mm thick shim brings the SWGCR0810E05 90° RH turning & facing tool almost exactly to center height, and good results were obtained turning 1" steel pipe. However facing 50mm steel bar stock to center found it to be slightly low, leaving a fractionally under 0.05 mm 'pip' so it needs another 0.03 mm to bring it fractionally above center. Fractionally too high is generally preferable to fractionally too low, due to tool deflection, so adding an 0.05 mm shim to the stack should produce optimum results.<br />
<br />
==== Inserts ====<br />
Ian B has purchased the spare inserts we needed in sets of five. He even was able to get the CK3 parting-off inserts which had been difficult to source!<br />
<br />
Inserts used in above tool set:<br />
* 3x SCMT06204 (square, indexable) https://www.rdgtools.co.uk/acatalog/SCMT-06-Carbide-Insert.html<br />
* 2x WCMT050308 (triangular, indexable) https://www.rdgtools.co.uk/acatalog/WCMT-05-T3-08-5XTIP-8813.html<br />
* 2x JCL15-120 (60 deg threading point) https://www.rdgtools.co.uk/acatalog/X5-JCL-15-120L-THREADING-TIPS-60-DEGREE--X5-TIP---23455.html<br />
* CK3 (parting off) https://www.rdgtools.co.uk/acatalog/CK3-CARBIDE-TIPS---PARTING--BOX-OF-5PCS--9437.html<br />
<br />
Inserts used in other tools:<br />
* 1x CK3 (as above) also missing from spare parting off tool<br />
* 1x 11IRA60 in Glanse threading bar + 1x spare<br />
<br />
=== Drills ===<br />
Various sizes of center drills are kept in a plastic bag next to the wooden accessories tray. There's also a small box of 2.5 mm center drills.<br />
<br />
We have a set of 11 TiN coated HSS drill bits from 1.5 to 8 mm, (in a cylindrical plastic index box) for tailstock drilling of brass, aluminium and non-abrasive plastics. To keep them sharp enough for the precision work we expect from the lathe, please don't use them for steel or reinforced plastics, and don't borrow them for non-lathe use. Metric and US [https://littlemachineshop.com/reference/numberdrillsize.php numbered]/[https://littlemachineshop.com/reference/letterdrillsize.php lettered] general use HSS drill bits are kept in two red metal index boxes next to the drill press.<br />
<br />
== Using the Lathe ==<br />
=== General ===<br />
A cutting speed chart for HSS tooling, published by Model Engineer magazine can be found [https://www.model-engineer.co.uk/sites/7/documents/cutting%20speed%20chart.pdf [here<nowiki>]</nowiki>]. The second row is the target feed rate and the rest of the chart, apart from the diameter column is RPM.<br />
<br />
For carbide tooling cutting iron and steels, recommended speeds are generally three times higher than for HSS, but the CJ18A 2500 RPM max. spindle speed (in high gear) means you can only reach the optimum speed range for over 15 mm dia work. For small diameter work, HSS tooling may well be a better choice.<br />
<br />
An online metric speeds calculator is here: https://www.cgtk.co.uk/metalwork/calculators/cuttingspeeds <br />
<br />
How to do the maths to calculate speeds and feeds: https://www.cutwel.co.uk/blog/speeds-feeds-made-easy<br />
<br />
Making dimensioned parts is primarily done by touching off the tool tip on a reference surface (with the lathe stopped, turning the chuck by hand), zeroing the handwheel dial, then manually counting turns and divisions. When backing off the tool its best to do so by exactly one whole turn so you don't forget the previous dial position. Stopping and measuring the work before taking the final cuts is essential if high accuracy is required. ''I've changed out the dial setscrews for flat tip ones with a tiny slug of solder under them so the dials are now friction fit on their shafts. i.e. if you hold the handle firmly taking up the backlash in the direction of cut, you can zero the dial just by grabbing and twisting it.''<br />
<br />
Carriage movement is less easy to measure as the handwheel is uncalibrated and advances an awkward bit over 19.2 mm per turn. Your options here when shoulders or other features must be exactly positioned are, in order of increasing accuracy: <br />
* Use measuring instruments, scribe the work at the desired length then work to the scribed line. Its often convenient to black the work with a permanent marker, then scribe with the tool tip, turning the chuck by hand.<br />
* for short distances, lock the carriage and use the compound, set parallel to the work<br />
* Set up a long travel dial indicator to measure carriage motion. <br />
N.B. with the leadscrew stopped, and the threading dial engaged, with its default 16 tooth gear, it will make one turn for every 24 mm of carriage movement (2 mm/div). This isn't accurate enough for positioning but is sufficient to check you aren't out by a whole mm or more.<br />
<br />
Do not allow any solvents to contact the chuck guard clear plastic as it will make the plastic brittle, or even craze it, and try to avoid melting it with the work light!<br />
<br />
=== Slide Locks ===<br />
* The carriage can be locked to the ways using the M5 hex screw through the top of the saddle to the left of the cross-slide. Double check the leadscrew is disengaged and the half-nuts open before locking it. Lock it when facing.<br />
* The cross slide can be locked by a M4 socket headed cap screw just in front of its middle gib screw. Locking the cross slide is helpful when turning very shallow conical features where the cross slide handle is in the way of the compound.<br />
* The compound slide can be locked by a M4 socket headed cap screw in line with the edge of the toolpost mount on the side with the gib adjustment screws. In normal use it should be kept backed off half a turn but it is desirable to tighten it for parting off operations to keep the resulting end faces flat.<br />
<br />
=== Chucks and Chuck Jaws ===<br />
==== Terminology ====<br />
* Inside jaws have steps on the outside to grip the ID of hollow work, but can also be used as outside jaws on small diameter parts (i.e. that fit through the spindle). <br />
* Outside jaws have steps on the inside to grip the OD of the work.<br />
* Universal chucks have a scroll plate with a spiral screw thread that moves all the jaws.<br />
* Independent chucks have individual adjusting screws for each jaw.<br />
<br />
==== The Chucks ====<br />
* The three jaw universal chuck can only grip near round or hexagonal work, which it centers, but its concentricity is not perfect so e.g. if you reverse the work and continue turning at the same diameter from the other end, you will see a line where the turned surfaces meet. It has separate sets of inside and outside jaws, and we normally keep the inside set installed to use as outside jaws for small diameter work.<br />
<br />
** Our jaws are individually numbered, stamped in the groove. They must be fitted in the correct sequence. The jaw slots are not clearly marked. Lowest runout for small dia. parts is achieved if you fit the jaws with #1 anticlockwise of the makers mark, then continue anticlockwise for #2 and #3.<br />
** A large strong rubber band is a great help getting all the jaws started on the scroll together - with slots #1 and #3 above the centerline and the scroll thread outer tip between #1 and #3, insert jaws #1 and #2 and put the rubber band round them to keep them in their slots. Insert jaw #3 and stretch the rubber band over it to hold it up into its slot. If the scroll was positioned correctly, all jaws should be at the same initial radius. The jaws can now be cranked in with the chuck key and they should all engage in step so they meet in the middle.<br />
:: ''Mini-lathe.com have the best instructions for [https://www.mini-lathe.com/mini_lathe/chucks/chucks.htm#Installing_Chuck_Jaws changing the jaws].'' <br />
<br />
* The four independent jaw chuck can grip most roundish or squarish work, which can either be carefully centered by the user, or deliberately gripped off-center. <br />
** Its jaws are reversible so can be swapped from inside to outside by simply cranking each jaw out and reinserting it the other way round, one at a time. DON'T move the jaws to different slots as they are likely to bind.<br />
** When setting up to face the sides of rectangular objects held crossways, it may be helpful to use both inside and outside jaw orientations, in symmetrical opposing pairs.<br />
** Its screws move their jaw 1/8" (3.125 mm) per turn<br />
<br />
* The jaws must '''never''' protrude from the chuck OD by more than one step, and for safety, its preferable they don't protrude at all, as they make the gap between the front of the bed and the chuck body an even more unforgiving meat grinder, and as the number of teeth engaged with the scroll or screw decreases, they loose strength, just when you need it the most to grip larger/heavier work. <br />
<br />
''Neither chuck is well suited to gripping tapered work safely. When seating work that doesn't quite fit through the chuck bore (which is larger than the 20mm spindle bore limit), be careful that it isn't seating on the chamfered edge of the chuck bore as it is far to easy to get the work slightly cocked so it doesn't run true.''<br />
<br />
==== Changing Chucks ====<br />
* When changing chucks, use the small grey plastic mat to protect the ways under the jaws in case you drop the chuck.<br />
* The spindle nose has two patterns of holes - the three hole pattern is for the three jaw chuck and the faceplate, and the four hole pattern is for the four jaw chuck. One hole is shared between the patterns, and is marked on the spindle nose.<br />
* To fit a chuck:<br />
** First check that the spindle nose and chuck back and recess are free of swarf, grit or other debris. Any foreign objects will tilt the chuck causing excessive runout and may mar the surfaces.<br />
** Remove the nuts and split lock washers from its studs, line its studs up with the hole pattern (preferably with the stud nearest anticlockwise to the makers mark through the marked spindle hole), fit and hold it in place with your right hand, and with your left, get the lock washer and nut on the top stud, and take up the slack.<br />
** One one nut is on, you no longer have to worry about dropping it, and can work round fitting the remaining washers and nuts, taking up the slack on each as you fit it. <br />
** Next, work round again getting them all finger tight, then tighten them gently, and finally work round fully tightening them. <br />
* Removal is the reverse of refitting. Put the washers and nuts back on the chuck's studs so they don't get lost.<br />
<br />
=== Faceplate Work ===<br />
Faceplate work is probably the most dangerous operation you can (or rather should) perform on a lathe. The working area is a large diameter spinning surface with protruding clamps to fixture the part that it is impractical to guard. Protruding clamps, studs, nuts etc. are very difficult to see at speed.<br />
<br />
'''Treat the faceplate with great respect and caution if you wish to continue to be able to count to ten on your fingers!''' <br />
<br />
The 65 mm cross-slide travel vs the 80 mm faceplate radius is a serious limitation that may require creative compound, toolpost and tool setups for larger parts, and doing full face cuts in two sections.<br />
<br />
''It is common practice to skim the faceplate to ensure it runs true. We have not (yet) done this, and wont till the spindle is in better bearings and the nose reground to minimise runout.''<br />
<br />
==== Clamping ====<br />
Open ended/sided clamps should be oriented so that cutting forces drive the work towards the clamping bolt/stud, not out from under the clamp. Minimize the protruding length of thread past the clamping nut, if necessary using sacrificial bolts or studs you can cut to length, or even using a long M8 stud for one of the faceplate mountings, so you can get a clamp nearer to the faceplate center. Double-check all clamps are secure, manually turn the faceplate to check the work and clamps clear the ways, top-slide and toolpost, and stand out of the 'line of fire' (a disc extending from the faceplate) when spinning up the work for the first time. <br />
<br />
If you need to machine close to a clamp, consider marking a safe limit circle on the faceplate and work with a marker pen to make it easier to see how close the cutting tool is to crash disaster. <br />
<br />
I strongly advise reading chapter two of Tubal Cain's book "Workholding in the Lathe" several times before your first faceplate setup, and if possible get another experienced lathe user to check your first few setups before spinning them up.<br />
<br />
==== Chuck Guard Removal ====<br />
The faceplate is too large diameter to fit under the chuck guard, but the guard has an interlock switch wqhich must be closed for the lathe to run. The guard is now fitted with wing nuts so it can be removed allowing the the interlock switch to close when using the faceplate. It *SHOULD* *ALWAYS* be refitted if a chuck is fitted, except when turning work too large to clear the guard. <br />
<br />
''The chuck guard is primarily there to make it very difficult to start the lathe without removing the chuck key and to reduce the area of large diameter spinning surface exposed. It may slow down the projectile if a chuck sheds a jaw but is unlikely to stop it. Also it serves to contain coolant spray spun off the chuck. As we don't use flood coolant this usually isn't an issue for us. As setting up for faceplate work doesn't use a chuck key, and the most hazardous zone is the face of the faceplate, with its spinning projecting clamps, with full access required for machining operations, which a guard would not cover, the consensus is that removing the guard is an acceptable risk.''<br />
<br />
=== Turning and Facing ===<br />
We are getting good results in aluminium, brass, and even steel using HSS cutting tools in quick-change tool holders, and the ~ 94 um/turn power feed. Unfortunately due to lack of rigidity in both the machine and smaller diameter parts, if you don't want the outer end to be over diameter, a light final cut and multiple 'spring' passes will probably be required.<br />
<br />
For aluminium, a sharp HSS tool and 0.5 mm (20 div) depth of cut gives good results with power feed for rapid stock removal. Its also easy maths as each cut takes ~ 1 mm off the diameter. Finish cuts should be much finer, 0.1 mm (4 div) is 'in the ballpark'.<br />
<br />
For steel, using carbide insert tooling, a 0.25 mm (10 div) depth of cut is more appropriate, and with pre-applied cutting oil, gives reasonable results with power feed if you use enough speed. The maths is not quite so easy as you are only taking 0.5 mm off the diameter per pass. Again, use finer finish cuts but try to plan your cuts so the final cut is still cutting, not smearing the surface!<br />
<br />
When facing or parting off, some skill is required to turn the cross-slide handwheel steadily to get a decent finish and to avoid shock-loading the tool tip. Increasing the spindle speed in one or more steps to keep up with the reducing diameter is advisable, but avoid speeds that cause resonances (resulting in chatter). When parting off, small through-hole parts may be caught on a thin rod chucked in the tailstock, and pre-positioned inside the work with its tip right up to the parting off position.<br />
<br />
==== Using the Steady Rests ====<br />
For the fixed steady rest, see Blondihacks' Lathe Skills #26 - How To Use a Steady Rest! [[#Youtube_Playlists_&_Videos|{below}]]<br />
<br />
Ours doesn't have ball bearing fingers, so a smooth surface on the work and adequate lubrication are essential. The thumbscrews can only tighten the fingers, so for small adjustments outwards you need to either slack off the clamping nuts or ease them slightly and use a drift against the back of the finger's slot. Once set, check the chuck still turns freely.<br />
<br />
The traveling steady rest needs to run on a machined surface, so at least for the first pass, must follow the tool, so its difficult to avoid using more compound slide overhang than is desirable. An initial surface should be cut next to the chuck or tailstock center before fitting the steady rest.<br />
<br />
Both are a PITA to fit - the fixed one has to have its clamping post inserted up through the bed, and the supplied spanner is useless near the headstock, and the travelling one's mounting holes on the saddle almost invariably need swarf picked out of them.<br />
<br />
==== Turning Between Centers ====<br />
<s>Using a MT3 to MT2 reducing sleeve, the MT2 dead center can be fitted in the spindle.</s> ''Currently the MT3 spindle taper is compromised.'' Alternatively, a soft center can be turned immediately before use in the three jaw chuck, but that must have its 60° point re-cut to concentric if the chuck is disturbed, and needs to be either large enough to bear on the chuck body, or must have a lip to bear on the end face of the jaws to take the axial thrust. Recutting the center is a PITA, as the compound angle must be set to 30° anticlockwise, then reset to a true 0° afterwards. Maybe a right-hand 30° end angle zero rake form tool is the answer, or use the carbide insert tool SSKCR0610H06 as a form tool with the toolpost rotated 15° anticlockwise.<br />
<br />
With the MT2 live center in the tailstock quill, this gives us a center either end of the work to hold it.<br />
<br />
We also need a drive dog similar to [https://littlemachineshop.com/products/product_view.php?ProductID=4473&category=1 this], and the corresponding drive post to bolt to the spindle nose. I have some 25mm bore thick wall iron pipe, which should do nicely. Lengths of the dog's straight tail and of the post TBD after I check how much the center protrudes. N.B. its recommended to tie the tail to the post to keep them in contact so they don't slam. ''Currently we will need to drive from the chuck jaws. Possibly use the exterior jaws with a short soft center gripped on the inside end and drive from the highest step.''<br />
<br />
=== Drilling ===<br />
Always start with a center drill so deflection of longer bits doesn't start the hole off-center. For larger bits (> 5 mm), first drill to the web size, then to final diameter. For a precision hole, drill slightly undersize and ream to final diameter. ''Supply your own reamers!''<br />
<br />
Caution: See note about the quill anti-rotation pin in section [[#Tailstock Quill|Tailstock Quill]] above.<br />
<br />
=== Boring ===<br />
Caution: As the spindle doesn't extend right through the headstock housing, if boring in a through hole, chips tend to fall out the back and tumble in the spindle bore till they fall into the change gears. To avoid this, one should plug the spindle bore with a wad of paper towel or rag and when cleaning up afterwards, use a rod to push it through towards the tailstock, with the chuck jaws (if fitted) wound clear of the spindle bore.<br />
<br />
A swivel bladed hole deburring tool (pale blue handle) can be found in the main room on the windowsill behind the drill press.<br />
<br />
A couple of boring jobs have been bodged with an awkwardly angled turning tool and achieving acceptable effective rake with enough clearance to reach deep enough into the hole has been problematic. I reviewed the tools we had and found none suitable for starting out in a 13mm bore, the max diameter we can (easily) drill. I therefore decided to buy a set of boring bars and make a holder for them. I had difficulty finding anything affordable under 10mm shank - the best low cost option was a [https://www.amazon.co.uk/dp/B07P5LGVBX set of nine 3/8" (9.525 mm) shank brazed carbide tipped boring bars], which would be close to the max capacity of the quick change boring bar holder - if we had one! Unfortunately this holder for our specific toolpost is difficult to find except in a toolpost bundle. Another annoyance is the variable tip height of the set, varying from 1.8 mm to 2.8 mm above the center of the shank.<br />
<br />
I therefore decided to make a boring bar holder of the [https://littlemachineshop.com/products/product_view.php?ProductID=1700 Littlemachineshop.com (USA) style] for use in the four way toolpost, as the additional rigidity will certainly help. Starting with a slightly over 50 mm length of 16 mm aluminium square bar and using the four jaw chuck , both ends were faced and an attempt was made to find its center and center drill it. It was then drilled out to ~9.8 mm after much drama due to blunt drills and drills that cut ~1mm oversize. Too big, but beggars cant be choosers as we didn't have a boring bar holder or a 3/8" reamer. Unfortunately the final hole ended up significantly off center. It was then chucked crossways and ~1 mm skimmed off its thickest side to gain clearance to allow it to be shimmed to height, then one side was slit lengthwise manually with a hacksaw.<br />
<br />
It was fitted to the for way toolpost and loaded with a booring bar, which clamped firmly. A 0.86 mm shim stack brought the tip of the largest boring bar almost spot on center height, with the difference easily accommodated by twisting the tool slightly. The three jaw chuck was then remounted, and a piece of iron pipe chucked for a test. It cuts well and leaves a decent surface finish.<br />
<br />
''The boring bar setup is a work in progress - talk to me before attempting to use them if you have a project that would benefit from boring..''<br />
<br />
ToDo: get something that can sharpen tools tipped with this grade of carbide - it needs some sort of diamond (or possibly CBN) wheel as green grit silicon carbide does little more than polish it. ''N.B. diamond wheels are rapidly eroded by grinding steel, so the supporting steel seat must be undercut with a regular grinding wheel before the diamond wheel can contact it.'' <br />
<br />
We'll also need 50 mm square sheet shims to fit under the toolpost to gain clearance in the toolpost above the tool or toolholder. A 2.4 mm shim would give us about the same above and below spindle center height, and we probably need a small selection of thinner ones.<br />
<br />
=== Thread Cutting ===<br />
The objective is to cut a thread that complies with the ISO metric thread profile. Our lathe is not currently equipped to cut non-metric threads, (with the exception of BA which have pitches based on metric threads of that era).<br />
<br />
[[File:ISO and UTS Thread Dimensions.svg|frame|center|Metric Thread Profile - from the geometry, H is ~86.6% of P]]<br />
<br />
Metric thread data - See 'Preferred Sizes' at: https://en.wikipedia.org/wiki/ISO_metric_screw_thread<br />
<br />
See "Mini Lathe User’s Guide" section '''Threading''' for general techniques *ONLY*, and above for change gears and threading dial setup.<br />
<br />
Amadeal specify the max. thread pitch as 2.5 mm. Any thread pitch greater than 1.5 nn requires the change gears to gear up. When gearing up it is desirable to distribute the ratio as evenly as possible over the two pairs of gears in the geartrain to avoid excessive tooth loading.<br />
<br />
==== External Threading ====<br />
Initially turn work to required Major Diameter, set up change gears and threading tool, touch off on the work, zero the top and cross slide dials, and do a 'scratch' pass to check the pitch. Back off the tool, return the carriage, and re-engage the half nuts on a valid dial line clear of the end of the thread then immediately stop the lathe, and hand turn the chuck till the tool tip is (hopefully) over the scratch to check the thread pickup. If all is good, return the carriage again, restart the lathe and start cutting your thread. <br />
<br />
Methods of doing so vary depending on the size of the thread and toughness of the metal, but straight-in plunge cutting is generally to be avoided as has the highest cutting forces, and does not reliably keep the carriage (and top-slide if set parallel to the work) loaded to avoid pitch errors due to backlash. <br />
<br />
If leaving the half-nuts engaged and reversing the lathe to return to the start of the thread for the next pass, its absolutely essential to back the tool out of the thread for the return pass as it will not follow the path of the cutting pass due to backlash in the geartrain, leadscrew mounts and half-nuts.<br />
<br />
==== Internal Threading ====<br />
''<nothing here yet>''<br />
<br />
== Cutting fluids ==<br />
=== Why bother? ===<br />
[https://youtu.be/mRuSYQ5Npek Watch this video] and contemplate what's actually happening to that thin ribbon of metal being removed. Most of the lathe's motor power is being turned into heat by internal friction in the chip being removed in the zone around the cutting edge, and surface friction at, and immediately behind the cutting edge, near-instantly heating the chip by up to several hundred degrees. Reducing the surface friction using a suitable cutting oil reduces the strain on the machine as a whole, and reduces workpiece and tool heating (and thus expansion) with consequent improvements in maximum usable feed and depth of cut, surface finish and accuracy. It also drastically increases the life of the cutting edge.<br />
<br />
=== Practicalities === <br />
We don't have a coolant system for the lathe and *really* don't want the maintenance hassles of using soluble cutting oil/coolant as if used infrequently its a PITA to keep recirculated high water content cutting fluids from going rancid and stinky, and they can also rust the ways, so even a total loss gravity feed system is problematic. Therefore if dry machining doesn't give a good enough finish, we tend to use oil applied topically, by hand to the work. <br />
<br />
* Hard brass is typically free-turning without oil, however some light oil for the final cut can improve surface finish, but with the disadvantage that it will increase loose chip buildup on the tool as hard brass typically forms short spalls or splinters rather than curly chips.<br />
<br />
* Many Aluminium alloys tend to be gummy, and Paraffin or other mineral spirits mixed with a little oil can help prevent the aluminum welding to the tool edge. WD40 will do at a pinch, but its messy to apply from a spray can.<br />
<br />
* Steel really needs *GOOD* cutting oil. Lard oil is the traditional choice for steel. If there are any objections to lard oil, we should bite the bullet and get some commercial dark high Sulphur cutting oil, but beware, many such oils use an additive package that includes lard oil.<br />
* Cast iron (except ductile) should be cut dry, as the carbon micro-inclusions self-lubricate it, and the carbide in the dust (primarily Cementite) are very abrasive, so tend to form a grinding compound if mixed with oil. <br />
<br />
I've sorted out an oil pot lid with a 1/2" brass collar soldered in to give a nice smooth sided hole, for ease of use and to minimize the risk of spills when using a brush to apply cutting oils, and got some dirt-cheap brushes. It fits Shippam's paste (and similar own-brand spread) jars and I've found several jars and ordinary lids to seal them for storage. Unfortunately it isn't the easiest to get this type of jars' lids back on square so they seal properly, and if you over-tighten them and there's a temperature change, they can be a total <expletive> to reopen. Using the rubberised handles of a large pair of pliers to grip the jar lid just above its rim is the best option, and avoids damaging the lids.<br />
<br />
''N.B. For the smaller brushes, the glue holding the bristles in is attacked by paraffin. To prevent loss of bristles, crimp the aluminium ferrule of each new brush of this type before use.''<br />
<br />
We have, in labelled jars:<br />
<br />
* Sulphurised Lard oil thinned with paraffin. Best choice for heavy cuts and threading in steel but stinky.<br />
* Lard oil thinned with paraffin. Good for steel and acceptable for softer copper alloys<br />
* Paraffin with a trace of light oil. Good for aluminium, and can help prevent squealing chatter on finish cuts in brass.<br />
<br />
I've also got some paraffin wax (in the form of a stubby candle), which can be applied lightly (under power) to brass and aluminium stock especially on the finish pass. It makes less mess than oil but unfortunately tends to build up on the tool tip, making it difficult to 'work by eye' without frequent pauses to clean the tool tip.<br />
<br />
We've also got a tin of [https://www.rocol.com/products/rtd-compound Rocol RTD cutting compound], which is a thick paste. Its highly recommended for drilling and tapping steel (in the drill press or by hand), but as a paste, is less useful for general lathe work unless thinned to a fluid consistency, e.g. with paraffin or white spirits. OTOH its certainly worth trying for high speed facing steel as it is less likely to get flung off.<br />
<br />
== Cleaning and Maintenance ==<br />
Swarf is a significant cut hazard to the operator, especially stringy swarf from cutting steel. Never touch it bare-handed - always use a tool e.g. a brush, or a hook, or needle nose pliers for grabbing long swarf.<br />
<br />
* After use, brush all swarf off the toolholder, compound and cross slide etc. ways and leadscrew. Ian B has blocked off the opening at the headstock end of the rear splashguard (to try to keep swarf out of the motor), so one must sweep the swarf towards the open tailstock end and catch it in a dustpan or similar. Preferably, also thoroughly clean out the chip tray under the lathe, but at least sweep out visible swarf.<br />
* Wipe up any cutting fluid residue and re-lubricate affected sliding surfaces with way oil.<br />
* Do not solvent clean the chuck guard, as it will make the plastic brittle, or even craze it. Water with a little detergent is permissible for cleaning it, with the guard totally removed from the lathe.<br />
<br />
Before engaging the half-nuts for power feed/threading, check the leadscrew is clean! ''Best cleaned under power, with a toothbrush.'' <br />
<br />
'''Caution:''' The traverse gears behind the carriage handwheel are in an open-backed housing and tend to become packed with swarf! Swarf buildup here will result in jerky carriage movement. Clean out as much as you can with a toothbrush ...<br />
<br />
===Lack of lubrication and/or swarf or dirt build-up can be disastrous===<br />
* If using the change gears/power feed, lack of lubrication of the B-C stub shaft center pin or either leadscrew end bearing can result in seizure and immediate destruction of one or more gears in the gear train or worse. <br />
* Small pieces of swarf can get between the saddle and ways, or into the slides degrading accuracy, possibly permanently if hard swarf scores them, or jamming them. The carriage handwheel gears behind the apron are notorious for accumulating swarf, and swarf buildup on the leadscrew can prevent the half-nuts engaging properly, resulting in scrapped work, and possibly stripped half-nuts. <br />
* Metal swarf can get into the motor (''though Ian B has modified the rear chip catcher to reduce the risk)'' or into the control box via the leadscrew, and short-circuit stuff. At best it will blow the fuse and need a strip-down to clean it out, at worst it may require a replacement [https://www.amadeal.co.uk/acatalog/Speed-Control-Circuit-Board--12amp-AMA_SP_CJ18_SCB12.html#SID=12 speed controller] ''(currently £96)'' and/or [https://www.amadeal.co.uk/acatalog/550W-motor-for-CJ18A-Mini-Lathe-467.html#SID=240 motor] ''(currently £105)'' and possibly other electrical parts. We should probably fit a [https://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C3-Mini-Lathe-Spares/C3-256-Leadscrew-Grommet-Dustproof-Cover C3-256 Leadscrew Grommet] to keep swarf out of the control box, as it tends to drop onto the 'Filter' board which is mounted horizontally, below the leadscrew.<br />
* Grit from grinding, sanding etc. forms a grinding paste with the way oil, and will rapidly wear out the ways, saddle and slides. Keep grit off at all costs e.g. by covering the ways and slides during grinding/sanding operations, and if there's any chance grit has gotten where it shouldn't, clean and re-lubricate *BEFORE* moving the carriage or slides, then move the carriage and slides, wipe down where they were with a clean paper towel and check there's no remaining traces of dirt other than clean way oil on the paper towel. If it doesn't come clean when you re-lubricate and move it again, a full strip down may be required to solvent clean and relubricate the precision sliding surfaces.<br />
* Although a metalworking lathe *can* be used to turn hardwood, wood dust and small chips are extremely pernicious, as they get everywhere, even clinging to clean surfaces, are abrasive due to their silica content, and are hygroscopic, promoting rust. An even more thorough clean-up than after using abrasives is needed, immediately afterwards. Oily wood dust and fine wood chips in significant quantities are a fire hazard, even in the trash bin.<br />
<br />
===Lubrication===<br />
See section: "Lubrication" in LittleMachineShop.com "Mini Lathe User’s Guide" [[Ian_M's_Lathe_Notes#Manuals|(below)]]. As we usually only open two nights a week, in the table on page 16, Daily lubrication becomes Weekly and Weekly becomes Monthly.<br />
<br />
===General Maintenance===<br />
* The grubscrews holding the cross-slide and compound slide dials tend to loosen due to vibration and use of the dials. Keep them snugged up, but not so tight the dials cant be set without an Allen key.<br />
<br />
* The screws holding the cross-slide nut tend to work loose due to vibration. Crank the handle to and fro through the backlash and visually check there is no movement of the screw heads in their holes. If there is, see the [[#Excessive_cross-slide_backlash|notes below]].<br />
<br />
===Removing the Carriage===<br />
Its possible to remove the carriage from the bed for cleaning etc. without dismantling it. The only stop to its motion is the righthand leadscrew bearing.<br />
<br />
Start by removing the tailstock. Crank the carriage to the tailstock end then remove the leadscrew bearing (two screws and a nyloc nut on the leadscrew end). With the half-nuts open, hold the leadscrew centered in them and crank the carriage off the end of its rack, then slide it off the end of the bed.<br />
<br />
Refitting is the reverse of removal, except (if its gibs are correctly adjusted) the carriage will be very tight on the end of the bed ways so may be difficult to work onto the ways without a stack of blocks of wood or similar to support it at exactly the right height. The righthand leadscrew bearing must be refitted with the carriage as close as possible to it and the half-nuts firmly closed to support the leadscrew at the correct height to hold it in alignment while the screws are being tightened. The nyloc nut controls leadscrew end-play. Fully tighten it then back it off slightly till the leadscrew turns freely with its change gear removed.<br />
<br />
If the Apron has been off, refit it with the screws no more than lightly finger tight and only finally tighten them after checking lead screw engagement at both ends of the carriage travel and that the rack and pinion operates smoothly over the full travel.<br />
<br />
== Issues and Annoyances ==<br />
As of September 2023 - mostly resolved, apart from the spindle bearings and runout, the lathe is in better condition than it has been for a number of years.<br />
<br />
===Four Jaw Chuck has two jaws too tight===<br />
Fixed 27/10/2023: The grooves in the opposite sides of the jaws that run in the chuck slots were slightly out of true, and the rails either side of the slots were slightly too thick towards the center. Due to the difficulty of seeing the high spots, after cleaning up and deburring the jaws didn't do enough to ease them, I decided to grind the top of the rails where they were binding. Several repetitions of spotting, grinding then diamond filing the high spots has eased them enough. I cleaned everything, greased the jaw slides and screws, and refitted the studs so the chuck is now fit for service. <s>Two of the chuck jaws are tight in their slots, making precise adjustment difficult due to lack of 'feel'. Moving the jaws round the slots shows the problem follows the jaw not the slot, and stoning various edges hasn't helped so it seems that the affected jaws are slightly oversize. Need Engineer's spotting blue to determine which of the sliding surfaces is binding, so we can see what needs scraping/stoning/grinding to fix them</s><br />
<br />
''N.B. Don't move the jaws to a different slot - the formerly tight jaws *must* stay in the slots furthest from the makers mark.''<br />
<br />
===Excessive Runout===<br />
Mostly fixed 24/10/2022: I ground the chuck seating surface of the spindle nose (outside lip) to under half a thou runout. This also cleaned up several burrs. It would be possible to do better, but that would need good spindle bearings, and a more rigid toolpost grinder mount.<br />
<br />
Our spindle nose was damaged years ago by a person with little mechanical aptitude (who shall remain nameless) beating it up with a hammer mushrooming the spindle nose. We are getting several thousandths runout at the end of the MT3 bore, a MT3 to MT2 reducer sleeve in it runs visibly out of true, as does the spindle nose flange. When you put a chuck on it, the runout is magnified by the distance from the spindle nose. Ideally we would replace the spindle when we change the bearings but its £52 [https://www.amadeal.co.uk/acatalog/4-Spindle-Upgrade-Real-Bull-Mini-lathe-CJ18-series-AMA_SP_CJ18_003RB.html#SID=9 from Amadeal] and money is tight. It may well require more work after the bearing upgrade. Once good bearings are in, if we can borrow a decent MT3 arbour as a reference, we should consider skimming the bore.<br />
<br />
===Spindle bearings===<br />
* The spindle bearings appear to be close to worn out. They are notably noisy when running, and there appears to be more slop in the spindle than is desirable. We have some ideas for possible replacement/upgrade, but it requires a major teardown.<br />
<br />
: The original bearings are allegedly 6206-2RS or 6206-ZZ deep groove ball bearings - 2RS codes rubber seals both sides and ZZ codes metal shields. Although the deep groove gives reasonable ability to withstand axial loads, the bearing balls point contact means they are vulnerable to [https://en.wikipedia.org/wiki/Brinelling brinelling] due to shock loading. The jammed on three jaw chuck didn't help this, as before we skimmed the spindle nose lip, it had to be driven off using a bar through the spindle bore, shock loading the bearings every time. Also even a minor 'crash' could have brinelled them due to eccentric shock loading, and the lathe has previously been crashed badly enough to need drive gear replacement. There are also issues with the 'approved' method of spindle and bearing removal from the headstock brinelling them, even if you don't abuse the spindle nose with a hammer!<br />
<br />
: A possible replacement is 30206 tapered roller bearings. The new bearings are slightly thicker so the plastic spindle spacer (15) needs to be machined to length to get the 45 tooth spur gear that drives the change gears laterally aligned with the tumbler gears. If a temporary replacement (3D printed?) is fitted, the lathe can be run (without power feed capability) so this can be done on the lathe after fitting the new bearings. As tapered roller bearings have line contact, they are significantly more resistant to brinelling.<br />
<br />
: ''See [[Talk:Ian_M%27s_Lathe_Notes]] for notes, links etc. for this upgrade.''<br />
<br />
===Motor stuttering===<br />
* Fixed 21/09/2023: The motor was running very erratically and it was very difficult to set a speed. Several loose connections were found in the control box, mostly loose female spades to the motor controller board, but also a dry jointed braking resistor on the 'Filter' board, and an inhibit wire completely off its terminal on the forward/reverse switch, making intermittent contact. After tightening and/or remaking all affected connections, it was much improved but still not right below 300 RPM. The remaining issues were due to poor wiper contact in the speed control pot, and stripping it, cleaning the track and contact ring and re-tensioning the contacts resulted in the motor now running smoothly over the full speed range. The speed is slow to settle, and while part of that is probably the lag in the digital tach, I suspect that the KBIC motor speed controller isn't properly tuned as it was (allegedly) previously replaced.<br />
<br />
===Drive belt slipping===<br />
* Fixed 28/9/2022: During testing the motor after the above issue, it was noted that the chuck could be stalled, slipping the drive belt, with not much torque. The drive belt was determined to be loose and a bit worn, but still in acceptable condition. <br />
<br />
: Access for servicing the belt requires removing the control box ''(2 spades to ZVR switch disconnect the supply, speed sensor and motor simply unplug from the 'filter board')'', the motor cover, chuck guard switch assembly + wiring cover, the change gear 'A' (drive) shaft carrier assembly, and the tumbler gear assembly. See https://youtu.be/EkxlIz01BdA for disassembly/reassembly, though on our lathe, the speed encoder ring on the spindle prevents the belt cover from being fully removed without disturbing the spindle nuts. There is enough room to work with it loose, but still trapped by the encoder ring. Also, unlike the video, if the 'jack' screws under the headstock are correctly adjusted, and the studs aren't excessively bent, there is no need to make custom studs. <br />
<br />
: It turns out that our lathe was missing the M6 hex headed jack screws that press the motor down to resist the belt tension, and the motor had cocked out of position at a severe angle. I know Ian B had had considerable trouble adjusting it after the motor fault back in October 2022, and I believe it had been getting slowly worse ever since. The jack screws were probably mistaken for headstock fixing bolts during disassembly after the crash that resulted in the metal Hi/Lo gears being fitted, then lost. The penny washers on the studs had dished, so I turned them over and backed them up with smaller washers and switched to nyloc nuts so they cant back off due to vibration. N.B. there is a packing washer on the motor side on one of the studs, presumably so the shaft is true to the ways. Adjusting the motor is awkward to say the least. One has to slack the stud nuts off a lot, pry under its rear end to lift it enough to be parallel to the ways, snug the stud nuts, check alignment, then set the jack screws and their lock nuts to hold it there, and finally tighten the stud nuts. <br />
<br />
: Tension: According to Sieg, it should be possible to twist the belt 90° mid span with a light finger grip. Other sources say 1/32" - 3/32" deflection mid span with light finger pressure.<br />
<br />
===Speed display blanking===<br />
* The speed display has been intermittent, blanking and flashing 8888 and 0 at certain speeds for as long as I have been using the lathe. Finally on 18/07/2022 it failed completely, with no display. I removed the display module and bench tested it - the pins are labelled 5V GND PL PE, PE is frame ground and PL is a TTL level pulse from the speed sensor - confirming that it was in good working order. My suspicions then turned to its power supply on the 'Filter' board. With both the sensor and display unplugged, the 5V rail was found to have a only a couple of volts, but the unreg DC was 17V and stable. Replacing the 78L05 5V regulator restored the 5V rail and normal operation.<br />
<br />
: ''I conclude its been failing for a while with high load current due to speeds with more lit segments causing it to drop out, resetting the speed display, causing it to blank, lowering the current enough for the regulator to recover, then the display MCU lamp tests (8888) then re-acquires the speed, repeating ad-nauseum till the speed is changed. I don't like the design as the high input voltage results in excessive dissipation.'' <br />
<br />
: ''ToDo: Bench test display to measure its worst case current consumption, then fit an appropriate dropper resistor to reduce the 78L05 dissipation.''<br />
<br />
===Quill spinning when drilling===<br />
* The quill was tending to spin while drilling because its anti-rotation pin (a M5 dog tip setscrew) was sheered. I've removed the debris, aligned the scale with the top of the tailstock and fitted a longer M5 dog-tip setscrew to replace it, with a nut to lock it at the correct height. N.B. the pin isn't that 'meaty' so if using big drills in tough metals, to prevent shearing it, it should be backed out so the quill can be turned by hand and unwanted rotation controlled by being quick with the quill lock if it starts to spin, or even using a close fitting rod in one of the chuck key holes with plastic tube over it to protect the ways. <br />
: ''If the screw sheers again, the quill will need to be removed and the tailstock taken off the lathe so the sheered tip can be shaken out, and if the setscrew is difficult to remove it probably means the threads are mangled where it sheered. Try driving it right through with the quill out.''<br />
<br />
===Sloppy quick change toolpost locking mechanism===<br />
* Once the dovetail clamp screw was slackened, there was nothing preventing the dovetail twisting or cocking significantly, and friction with the toolholder made it tend to do so, making toolholder insertion and removal more difficult unless the clamping screw was backed off excessively. I added a compression spring around the clamp screw inside the toolpost to push the dovetail outwards so it mostly retains alignment when open, allowing toolholders to slide on or off cleanly with far less screw slackening.<br />
<br />
===Leadscrew rubbing===<br />
* The leadscrew shaft is rubbing on the insulating separator inside the control box. Unfortunately the corner of the relay on the Filter Control Board (#160) doesn't allow enough clearance. Although the friction isn't much of a problem at high reduction ratios, e.g. 16:1 power feed, it increases the stress on the change gear train, and may be problematic when threading at feeds above 1:1. ''Possibly pack out the control box mountings by a couple of mm.'' <br />
<br />
===High/Low lever backwards!===<br />
* The high-low drive gear selector behind the headstock is incorrectly labelled and differs from the manual: low gear (which we normally use) is with the lever towards the tailstock. ''I suspect that the gears in the headstock were refitted the wrong way round when it was upgraded to metal gears.''<br />
<br />
: ''ToDo: Get it reassembled the right way round during the spindle bearing upgrade!''<br />
<br />
===Carriage lock fouls top slide===<br />
* The T handscrew has been replaced with a M5 hex headed bolt, to permit access when the top slide is over it. An 1/4" drive 8mm socket is usually left on it, but needs to be removed when the full cross slide travel is needed. The small (4 jaw) chuck key is near enough 1/4" to use for it. If you need to (un)lock it while the compound is over it, you'll need an 8mm spanner. ''The [https://www.amadeal.co.uk/acatalog/Mini-Lathe-Carriage-Lock-463.html Amadeal lock screw] is in the spares tin as it was too high and fouled the compound slide.''<br />
<br />
===Tailstock locking lever loose===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock - See full image for key to screws]]<br />
* Diagnosed and fixed 10/1/2023 - In the base of the upper section of the tailstock, there are two dog tip set screws that engage with locating grooves in the counter-rotating shafts carrying the eccentric locking cams. They'd backed off, probably due to vibration. They need to be tightened till they bottom out in the groove, making sure they are '''in''' the groove, backed off half a turn so the shafts can turn easily, and locked in place. There's no facility to do so, so reassemble with weak threadlocker. Unfortunately to get to them you have to remove the tailstock base slide, which is held on by the pressure of four adjusting grub screws, which all need backing off, and one socket headed bolt from underneath so full tailstock realignment is required after reassembly, which even for a rough alignment is tedious.<br />
: <s>The tailstock locking lever is loose and can be pulled out on its axis. It works OK when fully pushed home but needs investigating. ''I tightened the grub screw as the lever was coming off its shaft, but the whole shaft pushes/pulls in and out. It works OK fully pushed in, but it seems something that is meant to retain it has failed inside the tailstock base.</s><br />
<br />
===Gear alignment issues===<br />
* Change gear alignment is poor. I've currently got a gapped washer (to clear the key) packing out the A shaft so the gears line up, but this reduces the key's engagement so is problematic due to the high loading if the gears are set up for coarser threads. <s>Also I need to turn down some penny washers to slightly less than the root diameter of the metal 20T pinions, as gear retaining washers.</s> ''The gear retaining washers for A gear and B-C stub shaft are now done, turned down to slightly under 16 mm dia. Spares in the change gear tin. ToDo: The D (leadscrew) washer requires a larger center hole, so make two more with that hole.'' <br />
<br />
===Saddle gibs loose===<br />
* Fixed 11/04/2023: I took the apron off for access (and to clean the carriage handwheel gears), and found the front sheer plate screws were completely loose. I've snugged them up some and set the opposing grub screws and got a lot of the slop out. I've re-checked the front ones, and taken up the slop in the rear ones - Unfortunately it wasn't possible to get carriage movement to have an even 'feel' over its whole travel, and its noticeably tighter near the tailstock. If light hand pressure on the side of the unlocked carriage can cause movement (with the half-nuts open), its time to readjust them again, though it should be possible to move the carriage with a firm push. <s>The saddle gibs (actually the sheer plates) were too loose, to the point that engaging a slightly stiff threading dial could cause it to self-feed, an obvious crash hazard if working near the chuck or a step in the work.</s><br />
<br />
''N.B. the lefthand front opposing grubscrew is short, (fully recessed) and unlike the others does *NOT* have a locking nut as it must clear the traverse pinion. A wrap of PTFE tape provides enough friction to keep it in place, though possibly a bit of nylon fishing line down its hole would be better.''<br />
<br />
===Excessive cross-slide backlash===<br />
* ''Mostly Fixed <s>11/10/2022</s> again 07/11/2023:'' The cross-slide screw had excessive backlash (nearly three turns), possibly due to end float, which increases the risk of loosing track of the cut depth during threading operations. If you ended up off by a turn too far in, a crash was the most likely outcome.* 02/11/2023: The backlash is back up to one turn. I suspect the cross-slide screw nut mountings are working loose again.<br />
<br />
: So it turned out that the reason the cross-slide had nearly 3mm of backlash wasn't end float, it was loose cross-slide screw nut mountings. The nut has two socket headed cap screws pulling up, one either end, accessible from the top of the cross-slide, which control the tilt of the nut to take up backlash in the nut, and an opposing grub screw pressing down on the center of the nut to make it longitudinally rigid. I gambled the cap screws weren't too far out and snugged up the grub screw, and that immediately took out over 95% of the backlash which is now down to 10 divisions or so, or 0.25 mm. Shimming the cross-slide screw collar should take out some of what's left and careful adjustment of the nut tilt should get that down to under 0.1mm.<br />
<br />
: 07/11/2023: When the problem recurred I investigated further . It is difficult to get the cross-slide nut aligned correctly as it must be at the same height as the screw which is constrained by the bearing surfaces in the bracket. With the cross-slide almost at the front limit of its travel, I removed the screw and set the nut as level as possible and visually centered in the bore, then re-fitted the bracket and screw, then adjusted the tilt till it turned freely through the backlash. I then tilted it up at the front till some drag was felt to minimise the backlash and tightened the screws to lock it in place balancing them to maintain the same feel as I tightened them. The result was 7 divisions of backlash, acceptable but not great. During normal turning operations, the load on the nut is tension on the front screw and pressure on the grubscrew, so if it slackens again due to vibration from chatter, odds are it will be the rear screw that's loosened. <br />
<br />
* Further reduction of backlash: https://youtu.be/Wu_tI29JL2Y?t=163 <br />
: Brass tinned with Pb-free solder to form a white metal bearing surface should work at least as well as the bronze used in the video. The shim washer needs to be 10 mm ID and ~14 mm OD. It isn't necessary to remove the lead screw from the cross slide, as the washer can be fitted in-situ with only the bracket removed. Its also possible to closely estimate the required washer thickness from the backlash - note the number of dial divisions of backlash, then strip down the dial and bracket and with the gibs tight enough to keep the cross-slide from moving, push and pull the screw to assess its end float. A dial indicator mounted on the cross slide probing the screw flange will give you the total end float. Subtract the end float from the backlash, than take off another thou (0.025 mm) for running clearance to get the washer thickness (assuming it seats fully in the recess). If after fitting it, snugging up the bracket screws makes the screw too stiff to turn, the washer is too thick - either make another one or try to lap it down.<br />
: TLDR: measure flange on cross-slide screw and depth of recess in cross-slide bracket (behind dial) and machine a shim washer to take up nearly all the difference.<br />
<br />
===3 Jaw chuck didn't mount properly===<br />
* Fixed 7/4/2023 by grinding the spindle nose lip. The three jaw chuck can now be installed and removed by hand with no hammering. A test bar in it now has only 2 thou runout (TIR) at the chuck.<br />
: <s>The three jaw chuck and the faceplate aren't seating properly on the spindle nose. Its too tight on the register diameter of the lip. This results in grossly excessive runout, and also makes this chuck and the faceplate a PITA to fit or remove.</s><br />
: ''The spindle nose had been abused with a hammer (before my time) which mushroomed it and may have brinelled its bearings. See '''Excessive Runout''' and '''Spindle bearings''' above.''<br />
<br />
== Manuals, Books and other resources ==<br />
=== Manuals ===<br />
The [https://wiki.richmondmakerlabs.uk/images/a/a3/Lathe_InductionNotes.pdf RML CJ18A Mini-Lathe Induction Notes]. Your mandatory Lathe Induction will cover most of this but its good to be able to refer back to it.<br />
<br />
Official [https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Amadeal CJ18A Manual], or paper copy (less complete) kept on shelf above lathe.<br />
<br />
The [https://www.chesterhobbystore.com/wp-content/uploads/2022/11/Conquest-Super-Lathe.pdf Conquest Super Lathe manual] is considerably better than the Amadeal manual and is for a near-identical machine.<br />
<br />
The [https://littlemachineshop.com/images/gallery/info/minilatheusersguide.pdf Mini Lathe User’s Guide] from LittleMachineShop.com is even more comprehensive, going into its usage in some detail, with a proper TOC, and covers both US and Metric versions of Realbull Mini-lathes. ''The only fly in the ointment is the threading section assumes a US lead screw so change gear selections and threading dial divisions will not be correct for our lathe.''<br />
<br />
[https://www.arceurotrade.co.uk/machineguides/C3-Mini-Lathe-Dismantling-and-Reassembly-Guide.pdf Sieg C3 Mini-lathe Dismantling and Reassembly Guide] "A picture story book to help you dismantle and reassemble your Sieg C3 Mini-Lathe" ''It is similar enough to ours to serve as a maintenance guide, except for the electronics, spindle drive and other headstock innards.<br />
<br />
The motor controller is a clone of a [https://acim.nidec.com/drives/kbelectronics/-/media/kbelectronics/documents/dc-drives/manuals/kbic_manual.ashx?la=en KBIC® SCR DC Motor Speed Control]<br />
<br />
=== Books ===<br />
'''Metal Turning on the Lathe''', by David A Clark, Crowood Metalworking Guides, ISBN-13: 978-1847975232 [https://www.amazon.co.uk/gp/product/B00E78RKIG Kindle Edition (£8.99)]. ''A 'free' epub can be googled for, *NOT* linked here due to dubious legality.''<br />
<br />
'''[https://archive.org/details/03screwcuttinginthelathe Screwcutting In The Lathe]''', by Martin Cleeve (a pen-name of Kenneth C Hart), Workshop Practice series #3, ISBN-13: 9780852428382<br />
<br />
'''[https://archive.org/details/15workholdinginthelathe Workholding in the Lathe]''', by 'Tubal Cain' (a pen-name of Tom Walsh), Workshop Practice series #15, Argus Books, ISBN-10: 0852429088<br />
<br />
'''[https://archive.org/details/20metalworkandmachininghintsandtips Metalwork and Machining Hints and Tips]''', by Ian Bradley, Workshop Practice series #20, ISBN-13: 9780852429471<br />
<br />
'''[https://archive.org/details/38toolandcuttersharpening Tool and Cutter Sharpening]''', by Harold Hall, Workshop Practice series #38, ISBN-13: 9781854862419<br />
<br />
'''[https://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpaperT204.pdf Cutting Fluids]''', by EC Bingham, NIST Tech. Paper No. 204, 1921<br />
<br />
=== WWW resources ===<br />
==== Mini-lathe Specific ====<br />
There's a *LOT* of mini-lathe info online. Notable sites include:<br />
* http://www.mini-lathe.com/ - A major Realbull/Sieg mini-lathe resource.<br />
* http://mikesworkshop.weebly.com/lathe-modifications.html - many mods including carriage DRO autostop, and variable speed leadscrew motor drive, cross-slide motor drive, etc. He also has a page with a bunch of accessories, toolholders etc. - http://mikesworkshop.weebly.com/lathe-accessories-and-tooling.html<br />
* http://andysmachines.weebly.com/variable-speed-controls.html - Scroll down to the 'UPDATE' section for the schematic of a very similar SCR speed control board. It also has the schematic for an earlier version of the Auxiliary Control Board (aka: 'Filter' board).<br />
<br />
==== Forums ====<br />
''with publicly accessible archives''<br />
* https://groups.io/g/7x12MiniLathe - Mini-lathe specific, active<br />
* https://www.hobby-machinist.com/forums/mini-lathe-mini-mill-information.220/ - active<br />
==== Youtube Playlists & Videos ====<br />
* Blondihacks: [https://www.youtube.com/playlist?list=PLY67-4BrEae9Ad91LPRIhcLJM9fO-HJyN Lathe Skills] (playlist) - "This is an educational series to help you learn to use your metal lathe. Watch them in order for best results! Satisfaction not guaranteed, especially if you're a cranky sort of person."<br />
* Frank Hoose (Minilathe.com) has a couple of relevant Youtube playlists:<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn7ON0jGM5UbM-KZDT56MOIp Mini Lathe Operations]<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn4nGRZaVq3wTOlvZNOmdAZ2 Mini Lathe Overview]<br />
<br />
==== General Machining ====<br />
* https://www.machiningdoctor.com/ - "THE #1 MACHINING TECHNICAL HUB"<br />
<br />
==Projects==<br />
[[File:VESA mount.jpg|thumb|Machined VESA mounting plate (left) and plate from Dell monitor stand it must match (right). The translucent washer shows the size of the original center hole.]]<br />
* My first faceplate project was boring out the center hole in a VESA mounting plate to adapt it to fit onto a surplus Dell 1708FP monitor stand. The part was centered using the tailstock dead center engaging with its original center hole. I clamped the part with studs and penny washers on the driving side of two opposite corners, with cap screws in the next slot round to trap the corners under the clamping washers, then withdrew the tailstock and dead center. After machining out the bore, I used the tip of the tool, rotating the chuck by hand, to scribe a circle for laying out the bolt holes. I finished off laying out and drilling the bolt and locating holes by hand at home, fitted it to the stand, and mounted the 2nd hand LG 24" widescreen monitor.<br />
<br />
* Another ultimately unsuccessful project was fly cutting aluminum flat bar to thickness to make custom shims for the set of carbide insert tools, for the four way toolpost. The 8 mm shank tools need ~2.5 mm shim stacks, and the 6 mm shank tools need ~4.5 mm shim stacks. Ideally I'd machine single shims, but the only stock I've got handy cleans up to only 3.2mm, and some fine shimming may be needed to fine-tune the tool height.<br />
<br />
: After sorting out the clamps so they were no longer twisting the aluminum flat bar stock, and switching to the short 45° turning SCMT06204 insert tool in the four way toolpost, to improve rigidity and get a well controlled tip radius, the finish was much improved. I'm still having problems getting an even thickness and am getting approx. 0.05mm variation, I suspect due to the aluminium bar stock distorting due to internal stresses as its surface is cut away. ''ToDo: try supergluing the stock to the faceplate before clamping to further reduce chatter and stop the warping.''<br />
: Looking back on this project a year later, its fairly obvious that the thickness variation was probably due to faceplate surface runout due to the damaged spindle nose.<br />
<br />
* Raphael has been working on a steel rocket nozzle with some assistance from myself. We have set up the rough cut chunk of ~ 50mm steel bar, faced both ends (to 50mm length) and turned the OD to 49mm to clean it up. Its going to need through drilling, probably some boring, and quite a bit of detail work on the OD. It will then need to be transferred to a jig in the drill press vice to allow a pattern of angled traverse holes to be drilled with acceptable accuracy.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_Lathe_Notes&diff=17583Ian M's Lathe Notes2023-11-14T22:44:06Z<p>IanM: /* Slide Locks */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br />
<br />
''Currently these notes are semi-organized and non-authoritative. As I become more experienced with the RML CJ18A mini-lathe, I'm cleaning up, extending and reorganising them. Some lathe operating experience is assumed. If in doubt, '''*ASK*''' me, Andy H<sup>*</sup> , Jonathan H or another experienced minilathe operator!<br />
<br />
''* Andy H should be asked (for an authoritative answer) any questions involving RML usage policies or acquiring tooling or materials through RML.''<br />
<br />
== The Lathe ==<br />
Our Facilities page [[Facilities#Lathe|has]]:<br />
<blockquote><br />
'''Lathe'''<br />
[[File: Lathe2.jpg |200px|right | Lathe]]<br />
In the kitchen. <br />
<br />
Marked as a CJ18A Mini-Lathe from [[https://www.amadeal.co.uk/acatalog/CJ18A-Mini-Lathe-7x14-Machine-100mm-3jaw-Metric-With-Metal-Gears-AMA_LA_CJ18_M_3_MGRB.html Amadeal]]<br />
[[https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Manual]] <br />
<br />
[[Media:Lathe InductionNotes.pdf| Induction Document]]<br />
<br />
Possible upgrades:<br />
*https://www.youtube.com/watch?v=GwT-JQLbNPA<br />
<br />
''Please do not use the lathe until you have received induction'' <br />
<br clear=all><br />
</blockquote><br />
Its a Chinese import 7x14 mini-lathe. The 7x14 refers to the maximum diameter and length of work, in inches and is only a theoretical measure of the working envelope as you loose length to the chuck + any tailstock tooling, and the diameter is over the bed, not the cross-slide. See actual specifications below. <br />
<br />
Most if not all Chinese 7x10 to 7x16 mini-lathes seem to be remarkably similar (not uncommon with Chinese products due to [https://www.bunniestudios.com/blog/?p=284 Shanzhai (山寨)] )<br />
and the OEM of our Amadeal CJ18A Mini-Lathe was probably [https://www.made-in-china.com/showroom/cheap-lathe Yangzhou Realbull Machinery Co. Ltd]. Very similar lathes are also made by [https://www.siegind.com/lathe-machine.html Sieg], but their lathes tend to be slightly less sophisticated than the equivalent Realbull models.<br />
<br />
''N.B. Many Sieg parts are known to have slight but critical differences from Realbull parts, so '''DON'T''' order Sieg spares for a Realbull lathe!<br />
<br />
== Key Specifications ==<br />
Amadeal says the CJ18A Mini-Lathe is a 7x14 model with:<br />
<blockquote><br />
* Power 550 W<br />
* Distance between centres : 350 mm<br />
* Swing Over Bed: 180 mm<br />
* Swing Over Cross Slide: 110 mm<br />
* Taper: MT3<br />
* Tailstock Taper: MT2<br />
* Chuck diameter: 100 mm<br />
* Spindle Speed: 50 - 2500 rpm ''(with digital readout)''<br />
* Spindle Bore: 20 mm<br />
* Cross slide Travel: 65 mm<br />
* Range of Metric Threads: 0.5 - 2.5mm.<br />
</blockquote><br />
* The lead screw is metric, pitch 1.5 mm.<br />
* The spindle center is 90.6 mm above the flat of the bed (measured).<br />
<br />
Even though the compound and cross slide handwheels appear to be calibrated in thousandths of an inch, as ours is a metric machine, they only approximate that. One turn of a slide handwheel is 1mm advance, and they have 40 divisions, so each division is 0.025 mm, (approx. 0.984 [https://en.wikipedia.org/wiki/Thousandth_of_an_inch thou]). Similarly, the tailstock quill advances 1.25 mm per handwheel turn, which has 50 division dial, giving the same 0.025 mm divisions, but only 4 turns per 5 mm. The carriage handwheel is awkward - it moves approx. 19.2 mm per turn, and doesn't have a dial scale.<br />
<br />
== Notable Accessories ==<br />
We have:<br />
* [https://www.amadeal.co.uk/acatalog/160mm-Face-Plate-for-the-4-Mini-lathe-AMA_AC_CJ18A_FP160RB.html#SID=129 160 mm (6 1/4") Faceplate]<br />
* 100 mm (4") three jaw self-centering chuck (OEM standard) 22.5mm bore, with inside and outside jaw sets<br />
* 100 mm (4") four jaw (independent) chuck with reversible jaws (8 TPI screws)<br />
* Tailstock drill chuck (max. 13 mm dia.)<br />
* Live center for tailstock (+ OEM fixed center) <br />
* Four way Tool Post (OEM Standard)<br />
* [https://www.amadeal.co.uk/acatalog/Quick_Change_Tool_Post_for_the_mini-lathe.html Quick Change Tool Post] + 3 tool holders<br />
* [https://www.amadeal.co.uk/acatalog/Fixed-Steady-for-Mini-Lathes-AMA_AC_CJ18A_FSRB.html#SID=145 Fixed Steady Rest]<br />
* [https://www.amadeal.co.uk/acatalog/Travelling-Rest-for-Mini-Lathes-AMA_AC_CJ18_TSRB.html#SID=144 Travelling Steady Rest]<br />
<br />
''You'll find all of the above on the shelf above the lathe, with the accessories in the wooden box, apart from the steadies, which live next to it. Change gears, spare parts, and most cutting tool tips/blanks are in labelled white rectangular tins behind the lathe.''<br />
=== Measuring Tools ===<br />
We have:<br />
* Various dial indicators - the one with the adjustable magnetic base stand is the most convenient for most lathe setup work.<br />
* 25mm micrometer (in little grey case)<br />
* Grey case containing set of measurement tools including dial calipers, micrometer, steel rule (metric & inch), engineers square, and a fish-tail gauge<br />
<br />
''We currently lack''<br />
* ''A tool height setting gauge''<br />
<br />
=== Hand Tools ===<br />
Some common tools needed for normal use are kept with the lathe, in or attached to the wooden accessories box:<br />
* 2 mm Allen key - adjusting cross-slide and compound gibs<br />
* 4 mm Allen key - quick change toolholder tool clamping screws + height adjust, tightening dials<br />
* 5 mm Allen key - four way toolpost tool clamping screws, engaging/disengaging threading indicator<br />
* 6 mm Allen key - locking/unlocking quick change toolholder<br />
* 8 mm spanner - locking carriage when 8 mm socket can't be used, locking gib adjuster nuts <br />
* 13 mm spanner - changing chucks, locking steady rest jaws<br />
* Very long needle nose pliers - for grabbing swarf safely, holding one end of emery cloth safely so you can keep your fingers away from the jaws, and extricating small objects from awkward places.<br />
<br />
== Change Gears ==<br />
[[File:BC puller 1.jpg|thumb|Custom puller for B-C stub shaft]] [[File:BC puller 2.jpg|thumb|Pulling the B-C stub shaft]]<br />
See "Conquest Super Lathe" manual ([[#Manuals|below]]), section '''4.7 Change Gears''', PDF pages 28-29, but see below for mesh adjustment. The LittleMachineShop.com "Mini Lathe User’s Guide" (also below) section '''Threading''' gives a far better explanation, with pictures and diagrams, but its for a lathe with a US 1/16 inch pitch leadscrew, not a metric 1.5 mm pitch one like ours, so you *MUST* ignore all the tables in that section, replacing them with metric mini-lathe (with 1.5 mm pitch leadscrew) equivalents. <br />
<br />
We have the following tooth count gears: 20,20, 30, 35, 40,40, 45, 50,50, 60,60, 80,80<br />
which consist of the OEM power feed gears + the metric change gear set. Apart from the metal 20 tooth pinions, they are all plastic, probably Delrin if the molded in 'POM' marking can be trusted, but possibly plain Nylon 6, and are metric Module 1.<br />
<br />
If we wanted to add the capability to cut US/Imperial threads we'd need to buy additional 55, 57 and 65 tooth gears, and possibly a 21 tooth metal pinion.<br />
<br />
CGTK's [https://www.cgtk.co.uk/metalwork/calculators/changegears/minilathe?gears1=20,20,30,35,40,40,45&gears2=50,50,60,60,80,80&gears3= Change Gear Calculator] ''(link preloaded with our gear list)'' is useful if you don't want to calculate the ratios from first principles. Not all suggested combos will physically fit.<br />
<br />
* Take care *NOT* to loose the keys in the A and D shaft keyways - turn each shaft till the keyway is up before removing the gear. <br />
* The B and C gears are coupled by a hollow stub shaft (with an integral key), which is so tight in the gears it has to be pressed or driven out - I've made a puller just for this task, kept in the change gears tin.<br />
* The center of the B-C stub shaft *MUST* be lubricated where it runs on its pin on the change gear banjo bracket, with grease or heavy oil. ''Seizure of the stub shaft due to running dry is a frequent cause of catastrophic mini-lathe geartrain failures!''<br />
* Don't get oil on the change gears as it can cause plastic gears to crack. Only PTFE drylube or plastic compatible white grease should be used on their teeth. <br />
* Adjust the B-C pin position in the straight slot first to set the C to D gear mesh, tighten its nut, then swing the whole banjo about the D shaft boss to set the A to B mesh, and finally tighten the banjo clamping nut.<br />
* Check both gear meshes have running clearance by turning the chuck by hand enough to complete one full turn of the leadscrew, and by attempting to turn the intermediate gear(s) to assess backlash, If excessive resistance is felt or if there's significant backlash, readjust the gears. If you have difficulty judging the mesh, a strip of 80 gsm copier paper (approx. 0.1 mm thick) wound into the meshing teeth before tightening the stud or banjo will give appropriate clearance once removed. Once setup, check the gears run quietly under power.<br />
* If the sum of the tooth counts C+D is the same as for the ones you just removed and they were correctly meshed, you don't need to move the stub shaft pin. If A+B is <u>also</u> the same, you don't need to move the banjo. e.g. If it was set up for 16:1 reduction power feed, 1 mm (40:60 - 50:50) for M6 and 1.5 mm (e.g. 40:60:40) for M10 pitches can thus be achieved by only swapping gears. <br />
<br />
''The change gears, puller, etc. and a box spanner for the banjo nut are kept in a white rectangular tin behind the lathe.''<br />
<br />
=== Power Feed ===<br />
When used for turning with power feed, the change gears should be set for a 16:1 reduction (A:20 : B:80 - C:20 : D:80) using the pair of small metal 20 tooth pinions and the 80 tooth plastic gears (largest in set), for a feed of 0.09375 mm per turn (1.5 mm/16). Unless continuing your threading project the next session, please re-fit the 16:1 power feed set after threading so the power feed is ready for use. <br />
<br />
* *ALWAYS* leave the feed direction selector lever in its neutral (no feed) position, and the half-nuts open after use.<br />
* *ALWAYS* check the carriage lock is disengaged before engaging power feed. Unlock the carriage after use. <br />
<br />
=== Threading Dial ===<br />
The threading dial is an aid to re-engaging the half-nuts at the right moment so the tool will retrace its previous path cutting deeper, rather than offsetting axially some fraction of the thread pitch and ruining your work. Its based on the concept of the lowest integer multiples of the leadscrew and thread ''(being cut)'' pitches that exactly match, but for mechanical simplicity it only covers certain selected multiples of the leadscrew pitch.<br />
<br />
We have a choice of three pinion gears:<br />
{| class=wikitable<br />
|+ Threading dial Pinion Gears<br />
|-<br />
! Teeth !! Colour Dot !! Usable lines !! OD gear !! Dist. per turn<br />
|-<br />
| 14 || Red || 1,7 || 7.51 mm || 21 mm<br />
|-<br />
| 15 || Orange || 1,5,9 || 8.05 mm || 22.5 mm<br />
|-<br />
| 16 || Green || 1,4,7,10 || 8.37 mm || 24 mm (2 mm/div)<br />
|}<br />
They are now colour coded, with a paint dot on the gear end face ''(the only non-wear surface)''. The 16 tooth one is normally left on the lathe, but disengaged when not threading to minimise wear on the lead screw. The others are kept in the Change Gear tin.<br />
<br />
There's a threading dial 'pickup' calculator here: https://www.cgtk.co.uk/metalwork/calculators/threaddialindicator <br />
<br />
Initially select ''Lathe:'' '''Custom''', and enter the following below:<br />
* ''Units:'' '''Metric'''<br />
* ''Lead Screw Pitch (mm):'' '''1.5'''<br />
* ''Thread Dial Indicator Gear Teeth:'' '''16,15,14''' <br />
* ''Lines on Thread Dial Indicator:'' '''12''' <br />
* ''Line Marking:'' '''Every Line Numbered'''<br />
Note the teeth list is entered in reverse order so the resulting table highlights any required pinion changes.<br />
<br />
N.B. The dial is only friction clamped to the pinion by its center screw. If you have any reason to suspect it may not be properly aligned: <br />
# With the power off and the carriage unlocked, engage the feed direction lever upwards. You'll probably need to turn the chuck by hand to get it to engage.<br />
# If the threading indicator isn't already engaged, loosen the threading dial support block bolt, pivot the block to engage the pinion with the leadscrew and retighten the bolt.<br />
# Engage the half nuts, again turning the chuck by hand till they drop in. <br />
# Turn the chuck a couple of turns, top towards you to take up any backlash, then lock the carriage, taking care not to push it left while locking it.<br />
# Loosen the screw securing the dial to the pinion.<br />
# Align the '1' line of the dial with the index line, by rotating the dial clockwise, then retighten the screw.<br />
# Don't forget to disengage half-nuts and unlock the carriage!<br />
<br />
The above instructions should result in the half-nuts engaging cleanly when exactly on any valid line when threading towards the headstock. If it is required to thread away from the headstock, there will be a slight offset from the line due to backlash between the spindle gear and leadscrew, so engage slightly early.<br />
<br />
Changing the pinion:<br />
# Loosen the threading dial support block bolt and disengage from the leadscrew.<br />
# Undo dial center screw, and remove it and the dial, dropping the old pinion out the bottom.<br />
# Oil the shaft of the new pinion with a drop of light oil and insert it from below, gear end down.<br />
# Refit dial and screw.<br />
# Check the dial and pinion turn freely with minimal resistance.<br />
# Align as above.<br />
<br />
== Tailstock and Steadies ==<br />
These are mostly used to support long work ''(long with respect to its diameter)'' to improve rigidity, increasing accuracy and reducing chatter. The Tailstock quill is also used with a drill chuck for drilling.<br />
=== Tailstock ===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock base]]<br />
The tailstock can be offset to turn shallow tapers between centers. We don't currently have the accessories to turn between centers, namely <s>a MT3 dead center for the spindle, or</s> any drive dogs for the work. Also realigning the tailstock after turning a taper can be a PITA. The photo shows the tailstock adjusting screw locations ''(C - Lateral, and D - Skew)'' and the block on the baseplate they engage with. Adjustments can only take effect when the tailstock locking lever is eased to take the pressure off the baseplate. As we don't have a MT3 center, one has to turn a fresh point on a test workpiece for a rough tailstock alignment reference. Fine alignment, to avoid inadvertent taper turning, can be done by mounting a long precision ground bar between the chuck (or preferably a center in the spindle), and a dead center in the tailstock and sweeping it with a dial indicator on the carriage. Finally a test cut should be taken at either end of a bar between centers, and the diameters checked with a micrometer. Assuming the bed has previously been properly levelled and shimmed to take out twist ''(not the case at RML as we don't have it bolted down)'', any remaining difference in diameter will be double the tailstock offset, smaller at the tailstock being offset towards the front. Fine adjustment cant be achieved by jacking with the screws, its best to ease the adjusting screws, bump the tailstock into alignment then take up the screws again, checking the alignment is maintained when the tailstock is unlocked and relocked. There is no vertical adjustment, though shims can be added between the tailstock and its base.<br />
<br />
==== Tailstock Quill ====<br />
There is a metric/imperial scale on the top of the quill, read against the end of the tailstock, for depth measurement when drilling. The tailstock quill has a 1.25 mm pitch thread and a 50 division dial. Each division is therefore 0.025 mm, and it only takes 4 full turns of the handwheel to move the quill 5 mm. <br />
<br />
To eject MT2 taper tooling and centers from the tailstock, wind the quill all the way in.<br />
<br />
N.B. The quill anti-rotation pin (dog-tip setscrew + locking nut in top of tailstock near to the quill lock) is only M5. It will sheer if a large diameter drill jams in the work. Please back it out clear of its keyway if using large drills, and use alternative methods of preventing chuck rotation. To re-engage it, crank the quill out till you can see the keyway, align it with the screw and screw in the screw till it gently bottoms out, then back it off a quarter turn. Try twisting the quill to check its properly engaged, then tighten the locking nut gently to hold the screw in position clear of the bottom of the keyway.<br />
<br />
=== Steady Rests ===<br />
We have two, both with brass tips that must be kept lubricated during use.<br />
<br />
The fixed steady mounts on the ways, and is most useful when turning longer work that wont fit through the spindle bore. Adjustment is critical, and the surface the tips run on must be smooth and concentric, as any misalignment that forces the work off center will result in the work wobbling in the chuck, marring it, with a high risk of it becoming un-chucked, which can be dangerous at speed.<br />
<br />
The travelling steady mounts to the headstock side of the carriage to locally resist the deflection of thin long work, due to the cutting forces. It only has two tips, to resist climb, and deflection away from the tool, and requires readjustment after every cutting pass.<br />
<br />
== Tooling and Tool Holders ==<br />
'''Key dimensional data:'''<br />
* The quick change holders accept up to 10 mm shank tools. <br />
* The four way toolpost has 50 mm long sides, a seat width of 15 mm and can clamp tools of up to 5/8" (15.875 mm) shank ''(check this)'', but the slot base is only 10.4 mm below the spindle center so cannot be used with >10 mm shank tooling unless it has a dropped tip. Large tooling with a centered tip is also problematic as you run out of height above the shank when trying to shim to match the spindle center height. <br />
<br />
===Quick Change Toolpost===<br />
I've got the quick change toolpost and toolholders setup for mostly easy use. The three toolholders came with cantilever height setting arms which historically haven't been installed as the supplied fixing screws were too short. That's all now sorted out and a HSS RH turning tool and a HSS hand-ground grooving/parting-off tool are now mounted in two of the holders and set to height. The third is kept free for other tools. <br />
<br />
The quick change toolpost has been modified with a spring to press the dovetail clamp outwards and help stop it twisting or flopping about to ease toolholder fitting and removal. The dovetail clamp (socket headed screw on toolpost side opposite dovetail) feels a bit stiffer than before, but will take less than half a turn to go from open (with the toolholder lifting out or dropping in easily) to fully clamped. As there is so much less clearance in the open position you should no longer need to wiggle the toolholder while clamping it to get a consistent height. If the dovetail clamp ever gets misaligned, twist it straight by eye, slacken off a bit further than usual to get a toolholder on, clamp it to align the dovetail then release, reseat the toolholder and re-clamp to ensure its at its preset height. You cant adjust the height by 'jacking' with the height screw due to its offset leverage. Instead, back off the height screw and hold the toolholder at the desired height while locking the dovetail clamp, then adjust the height screw (and locking nut) to hold it there, then check it doesnt change height significantly when you unclamp and reclamp the dovetail. <br />
<br />
Unfortunately the OEM height setting screws foul the toolpost locking nut handle. Currently, if you need to swap toolposts you will have to first remove the quick-change tool holder from the post. There is enough nut handle swing to allow the quick change toolpost to be unclamped and rotated to fine set the tool angle without removing the toolholder. It also seems the mating surfaces may be slightly out of square, as if you rotate the toolpost 90° or 180°, the nut swing may be insufficient to re-clamp it without removing the toolholder to do so. Add a M10 washer under the locking nut if the handle ends up pointing in an undesirable direction! A thin M10 washer is kept with the toolpost collar for this purpose, and will shift the handle position by about a third of a turn. <br />
<br />
''ToDo: Make a taller nut of a similar pattern, to clear the height setting screws.''<br />
<br />
===Four Way Toolpost===<br />
The OEM four way toolpost is significantly more rigid than the quick change toolpost + holders because it has fewer and thicker parts and less overhang. Therefore the four way toolpost should be used when using carbide tooling. It requires shimming under the tool to set the tip height to the spindle center height - see below. The tool shanks are mostly significantly less than 15 mm wide, so need to be centered under its clamping screws, tempting as it is push the shank in for full side contact with the toolpost. If possible clamp the shank with all three screws not just two.<br />
<br />
==== Shimming ====<br />
We typically only mount up to two tools, and want maximum rigidity, so use 50 mm x 15 mm shims, (the full seat area), preferably with deburred edges and radiused corners so they aren't a hazard to the operator.<br />
<br />
We have pre-cut and marked shims of the following thicknesses: <br />
* 1x 3.23 mm, 2.42 mm, 1.56 mm, 0.32 mm, and 0.25 mm<br />
* 2x 1.00 mm, 0.77 mm, 0.12 mm, 0.11 mm, 0.10 mm and 0.05 mm<br />
* 4x 0.53 mm<br />
<br />
Our shims are mostly found materials (hence the awkward thicknesses) and are mostly a mixture of aluminium and steel, with a couple of GRP ones. The toolpost seat '''<u>must be absolutely clean</u>''' to avoid embedding debris in the aluminium or GRP shims, to get a consistent height and avoid tilting the tool - wipe it every time you change a tool! Put the thin shims at the bottom of the stack to avoid the tool shank edges creasing them. Shims are kept in a little yellow plastic box with a clear lid, near the carbide tools case.<br />
<br />
''ToDo:'' <br />
<br />
* ''Cut more shims neatly, mark them with their thickness.''<br />
* <s>''Do test cuts and start noting shim stack-ups for various tools.''</s><br />
* ''Organise shim storage!''<br />
* <s>''Possibly acquire, cut down and dismantle a feeler gauge set to get a better selection of marked steel shims.''</s><br />
* ''Make a tip height setting gauge''<br />
<br />
=== HSS Tools ===<br />
[[File:Tool Bit Geometry.jpeg|thumb|Single point cutting tool geometry]]<br />
Our HSS tools are made from 8 mm square bar stock, hand-ground to tip profile in-house. See LittleMachineShop's [https://littlemachineshop.com/images/gallery/instructions/grindingtoolbits.pdf Grinding Tool Bits] notes. <br />
<br />
I've installed our usual HSS LH turning and parting off tools in two of the quick change holders and set the heights correctly. There are a couple of other HSS tools or tool blanks knocking about. Taking heavy cuts turning steel (even with good cutting oil) blunts HSS tools fairly quickly, which are time-consuming to re-sharpen nicely without a dedicated tool & cutter grinder with appropriate jigs. Its worth noting that the usual 'speeds & feeds' tables are commonly based on surface speeds expected to give a half hour (active cutting) tool life before resharpening.<br />
<br />
I touched up the LH turning tool by lapping on wet & dry (silicon carbide) paper on glass (Aka: [https://en.wikipedia.org/wiki/Scary_sharp 'Scary Sharp']) working upwards through the grits 200, 400, 600 and finally 1000, initially 'bluing' the surfaces to be lapped with a marker pen to see which areas needed taking down more. The end of the tool was significantly uneven so I touched that up freehand on the bench grinder to flatten it when it became apparent that 200 grit lapping wasn't cutting where it needed to. There was an existing micro-bevel on the leading side, which I kept. Finally I 'dubbed' the leading corner vertical edge on the 1000 grit to give it a very slight nose radius. A test cut on brass gave a very nice finish when turning.<br />
<br />
''Ian B has purchased some spare 8mm HSS tool blanks - talk to a lathe trainer if your proposed lathe work needs custom ground HSS tooling.'''<br />
<br />
=== Brazed Tungsten Carbide Tools ===<br />
Somewhat of a half-way house between hand ground HSS tooling and insert tooling with the disadvantages of both and some more besides - e.g. they are much harder to sharpen. So why do we bother? Some tool geometries would be awkward and tedious to hand grind, and Chinese import brazed carbide tooling is about half the price of similar HSS tooling, and far more readily available. Also, for space constrained tooling like boring bars, if you want carbide, for insert tooling, the size of the insert and its clamping seriously limits the minimum hole diameter you can work in. I have purchased a set of 3/8" shank brazed carbide tipped boring bars, but we currently cant sharpen them, due to lack of a diamond grinding wheel. <br />
<br />
=== Tungsten Carbide Insert Tools===<br />
Decoding ISO insert tooling part numbers: https://www.cutwel.co.uk/blog/learn-the-turning-tool-iso-code-system<br />
[[File:Carbide set.jpg|800px|thumb|left|Our set of Tungsten carbide insert lathe tools (before the new inserts were fitted)]]<br />
<br />
{| class=wikitable<br />
|+ Tools, left to right, (+ last across top):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| SSKCR0610H06 || 75° through boring || SCMT06204 || Long || 6 || 6.34 || ''4.33''<br />
|-<br />
| SSSCR0610H06 || 45° deep facing, internal chamfering || SCMT06204 || Long || 6 || 6.13 || ''4.58''<br />
|-<br />
| SWUCR0610H05 || 93° boring, deep facing || WCMT050308 || Long || 6 || 6.22 || ''4.48''<br />
|-<br />
| SWGCR0810E05 || 90° RH turning & facing || WCMT050308 || Short || 8 || 8.25 || '''2.45'''<br />
|-<br />
| SSSCR0610E06 || 45° turning, chamfering || SCMT06204 || Short || 8 || 8.75 || ''1.93''<br />
|-<br />
| SSBCR0610E06 || 75° RH turning, chamfering || SCMT06204 || Short || 8 || 8.72 || ''1.98''<br />
|-<br />
| LW0810R-04 || 60° external threading || JCL15-120 || Short || 8 || 7.44 * || ''3.28''<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || 8.23 || ''2.5 ?''<br />
|-<br />
| LN0813R-04 || 60° internal threading || JCL15-120 || Long || 7.95 || 7.44 * || ''3.28''<br />
|}<br />
<br />
{| class=wikitable<br />
|+ More Tools, (loose in tin):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || ~8.5 (not in use) ||<br />
|-<br />
| [https://www.glanze.co.uk/product/glanze-12-mm-60-degree-metric-internal-threading-tool/ Glanse SIR0012K11] || 60° internal threading bar || 11IRA60 || Long || 12 dia || ??? || ???<br />
|}<br />
''Shim stack heights in bold are tested, in italic are only calculated.'' ''Tip heights marked * are with new JCL15-120I inserts. The single remaining plain JCL15-120 insert has a slightly higher tip height.''<br />
<br />
Carbide tooling typically requires two to three times more speed than HSS and at least a couple of 'thou' depth of cut for best results.<br />
<br />
Chatter can rapidly kill carbide tooling by chipping the cutting edge. To improve rigidity and reduce the risk of chatter, the cross-slide and compound gib screws need to be well adjusted so there is minimal play in the slides, tool stick-out should be minimised, the four way toolpost should be kept over the cross-slide, and the work should be kept close to the chuck (or otherwise supported by tailstock or steady rest) to avoid excessive deflection.<br />
<br />
Thermal shock is almost instant death to carbide, and when dry cutting the insert tip can run very hot, so do not add extra cutting fluid manually during the cut. Pre-apply what you need, evenly, before starting the cut.<br />
<br />
Parting off or facing to center is high risk - if the tool tip is even slightly below center or if tool or work deflection takes it below center, the work will tend to climb over the tool tip as the cut approaches center, breaking the insert. To avoid this, the tool should be shimmed slightly above center, sufficient to allow for work and tool deflection, and unless very close to the chuck, a steady should be used. Its often preferable to part to a couple of mm dia. remaining then stop and saw through the remainder. Parting off hollow parts is much lower risk.<br />
<br />
Further investigation of the Tungsten carbide insert tool height situation is not encouraging - the so-called 'set' in question does not have a consistent tip height ''(see above table)''! In a real set, the insert seats *should* be machined allowing for the insert thickness to bring all the cutting edges to the same height with respect to the shank underside. However if you place them tip to tip on a table its easy to see there is considerable height variation, so they need to be individually shimmed (or at best, one machined shim will only be right for two or three tools). At this time we don't have dedicated shim stacks for each tool.<br />
<br />
A 2.42 mm thick shim brings the SWGCR0810E05 90° RH turning & facing tool almost exactly to center height, and good results were obtained turning 1" steel pipe. However facing 50mm steel bar stock to center found it to be slightly low, leaving a fractionally under 0.05 mm 'pip' so it needs another 0.03 mm to bring it fractionally above center. Fractionally too high is generally preferable to fractionally too low, due to tool deflection, so adding an 0.05 mm shim to the stack should produce optimum results.<br />
<br />
==== Inserts ====<br />
Ian B has purchased the spare inserts we needed in sets of five. He even was able to get the CK3 parting-off inserts which had been difficult to source!<br />
<br />
Inserts used in above tool set:<br />
* 3x SCMT06204 (square, indexable) https://www.rdgtools.co.uk/acatalog/SCMT-06-Carbide-Insert.html<br />
* 2x WCMT050308 (triangular, indexable) https://www.rdgtools.co.uk/acatalog/WCMT-05-T3-08-5XTIP-8813.html<br />
* 2x JCL15-120 (60 deg threading point) https://www.rdgtools.co.uk/acatalog/X5-JCL-15-120L-THREADING-TIPS-60-DEGREE--X5-TIP---23455.html<br />
* CK3 (parting off) https://www.rdgtools.co.uk/acatalog/CK3-CARBIDE-TIPS---PARTING--BOX-OF-5PCS--9437.html<br />
<br />
Inserts used in other tools:<br />
* 1x CK3 (as above) also missing from spare parting off tool<br />
* 1x 11IRA60 in Glanse threading bar + 1x spare<br />
<br />
=== Drills ===<br />
Various sizes of center drills are kept in a plastic bag next to the wooden accessories tray. There's also a small box of 2.5 mm center drills.<br />
<br />
We have a set of 11 TiN coated HSS drill bits from 1.5 to 8 mm, (in a cylindrical plastic index box) for tailstock drilling of brass, aluminium and non-abrasive plastics. To keep them sharp enough for the precision work we expect from the lathe, please don't use them for steel or reinforced plastics, and don't borrow them for non-lathe use. Metric and US [https://littlemachineshop.com/reference/numberdrillsize.php numbered]/[https://littlemachineshop.com/reference/letterdrillsize.php lettered] general use HSS drill bits are kept in two red metal index boxes next to the drill press.<br />
<br />
== Using the Lathe ==<br />
=== General ===<br />
A cutting speed chart for HSS tooling, published by Model Engineer magazine can be found [https://www.model-engineer.co.uk/sites/7/documents/cutting%20speed%20chart.pdf [here<nowiki>]</nowiki>]. The second row is the target feed rate and the rest of the chart, apart from the diameter column is RPM.<br />
<br />
For carbide tooling cutting iron and steels, recommended speeds are generally three times higher than for HSS, but the CJ18A 2500 RPM max. spindle speed (in high gear) means you can only reach the optimum speed range for over 15 mm dia work. For small diameter work, HSS tooling may well be a better choice.<br />
<br />
An online metric speeds calculator is here: https://www.cgtk.co.uk/metalwork/calculators/cuttingspeeds <br />
<br />
How to do the maths to calculate speeds and feeds: https://www.cutwel.co.uk/blog/speeds-feeds-made-easy<br />
<br />
Making dimensioned parts is primarily done by touching off the tool tip on a reference surface (with the lathe stopped, turning the chuck by hand), zeroing the handwheel dial, then manually counting turns and divisions. When backing off the tool its best to do so by exactly one whole turn so you don't forget the previous dial position. Stopping and measuring the work before taking the final cuts is essential if high accuracy is required. ''I've changed out the dial setscrews for flat tip ones with a tiny slug of solder under them so the dials are now friction fit on their shafts. i.e. if you hold the handle firmly taking up the backlash in the direction of cut, you can zero the dial just by grabbing and twisting it.''<br />
<br />
Carriage movement is less easy to measure as the handwheel is uncalibrated and advances an awkward bit over 19.2 mm per turn. Your options here when shoulders or other features must be exactly positioned are, in order of increasing accuracy: <br />
* Use measuring instruments, scribe the work at the desired length then work to the scribed line. Its often convenient to black the work with a permanent marker, then scribe with the tool tip, turning the chuck by hand.<br />
* for short distances, lock the carriage and use the compound, set parallel to the work<br />
* Set up a long travel dial indicator to measure carriage motion. <br />
N.B. with the leadscrew stopped, and the threading dial engaged, with its default 16 tooth gear, it will make one turn for every 24 mm of carriage movement (2 mm/div). This isn't accurate enough for positioning but is sufficient to check you aren't out by a whole mm or more.<br />
<br />
Do not allow any solvents to contact the chuck guard clear plastic as it will make the plastic brittle, or even craze it, and try to avoid melting it with the work light!<br />
<br />
=== Slide Locks ===<br />
* The carriage can be locked to the ways using the M5 hex screw through the top of the saddle to the left of the cross-slide. Double check the leadscrew is disengaged and the half-nuts open before locking it. Lock it when facing.<br />
* The cross slide can be locked by a M4 socket headed cap screw just in front of its middle gib screw. Locking the cross slide is helpful when turning very shallow conical features where the cross slide handle is in the way of the compound.<br />
* The compound slide can be locked by a M4 socket headed cap screw in line with the edge of the toolpost mount on the side with the gib adjustment screws. In normal use it should be kept backed off half a turn but it is desirable to tighten it for parting off operations to keep the resulting end faces flat.<br />
<br />
=== Chucks and Chuck Jaws ===<br />
==== Terminology ====<br />
* Inside jaws have steps on the outside to grip the ID of hollow work, but can also be used as outside jaws on small diameter parts (i.e. that fit through the spindle). <br />
* Outside jaws have steps on the inside to grip the OD of the work.<br />
* Universal chucks have a scroll plate with a spiral screw thread that moves all the jaws.<br />
* Independent chucks have individual adjusting screws for each jaw.<br />
<br />
==== The Chucks ====<br />
* The three jaw universal chuck can only grip near round or hexagonal work, which it centers, but its concentricity is not perfect so e.g. if you reverse the work and continue turning at the same diameter from the other end, you will see a line where the turned surfaces meet. It has separate sets of inside and outside jaws, and we normally keep the inside set installed to use as outside jaws for small diameter work.<br />
<br />
** Our jaws are individually numbered, stamped in the groove. They must be fitted in the correct sequence. The jaw slots are not clearly marked. Lowest runout for small dia. parts is achieved if you fit the jaws with #1 anticlockwise of the makers mark, then continue anticlockwise for #2 and #3.<br />
** A large strong rubber band is a great help getting all the jaws started on the scroll together - with slots #1 and #3 above the centerline and the scroll thread outer tip between #1 and #3, insert jaws #1 and #2 and put the rubber band round them to keep them in their slots. Insert jaw #3 and stretch the rubber band over it to hold it up into its slot. If the scroll was positioned correctly, all jaws should be at the same initial radius. The jaws can now be cranked in with the chuck key and they should all engage in step so they meet in the middle.<br />
:: ''Mini-lathe.com have the best instructions for [https://www.mini-lathe.com/mini_lathe/chucks/chucks.htm#Installing_Chuck_Jaws changing the jaws].'' <br />
<br />
* The four independent jaw chuck can grip most roundish or squarish work, which can either be carefully centered by the user, or deliberately gripped off-center. <br />
** Its jaws are reversible so can be swapped from inside to outside by simply cranking each jaw out and reinserting it the other way round, one at a time. DON'T move the jaws to different slots as they are likely to bind.<br />
** When setting up to face the sides of rectangular objects held crossways, it may be helpful to use both inside and outside jaw orientations, in symmetrical opposing pairs.<br />
** Its screws move their jaw 1/8" (3.125 mm) per turn<br />
<br />
* The jaws must '''never''' protrude from the chuck OD by more than one step, and for safety, its preferable they don't protrude at all, as they make the gap between the front of the bed and the chuck body an even more unforgiving meat grinder, and as the number of teeth engaged with the scroll or screw decreases, they loose strength, just when you need it the most to grip larger/heavier work. <br />
<br />
''Neither chuck is well suited to gripping tapered work safely. When seating work that doesn't quite fit through the chuck bore (which is larger than the 20mm spindle bore limit), be careful that it isn't seating on the chamfered edge of the chuck bore as it is far to easy to get the work slightly cocked so it doesn't run true.''<br />
<br />
==== Changing Chucks ====<br />
* When changing chucks, use the small grey plastic mat to protect the ways under the jaws in case you drop the chuck.<br />
* The spindle nose has two patterns of holes - the three hole pattern is for the three jaw chuck and the faceplate, and the four hole pattern is for the four jaw chuck. One hole is shared between the patterns, and is marked on the spindle nose.<br />
* To fit a chuck:<br />
** First check that the spindle nose and chuck back and recess are free of swarf, grit or other debris. Any foreign objects will tilt the chuck causing excessive runout and may mar the surfaces.<br />
** Remove the nuts and split lock washers from its studs, line its studs up with the hole pattern (preferably with the stud nearest anticlockwise to the makers mark through the marked spindle hole), fit and hold it in place with your right hand, and with your left, get the lock washer and nut on the top stud, and take up the slack.<br />
** One one nut is on, you no longer have to worry about dropping it, and can work round fitting the remaining washers and nuts, taking up the slack on each as you fit it. <br />
** Next, work round again getting them all finger tight, then tighten them gently, and finally work round fully tightening them. <br />
* Removal is the reverse of refitting. Put the washers and nuts back on the chuck's studs so they don't get lost.<br />
<br />
=== Faceplate Work ===<br />
Faceplate work is probably the most dangerous operation you can (or rather should) perform on a lathe. The working area is a large diameter spinning surface with protruding clamps to fixture the part that it is impractical to guard. Protruding clamps, studs, nuts etc. are very difficult to see at speed.<br />
<br />
'''Treat the faceplate with great respect and caution if you wish to continue to be able to count to ten on your fingers!''' <br />
<br />
The 65 mm cross-slide travel vs the 80 mm faceplate radius is a serious limitation that may require creative compound, toolpost and tool setups for larger parts, and doing full face cuts in two sections.<br />
<br />
''It is common practice to skim the faceplate to ensure it runs true. We have not (yet) done this, and wont till the spindle is in better bearings and the nose reground to minimise runout.''<br />
<br />
==== Clamping ====<br />
Open ended/sided clamps should be oriented so that cutting forces drive the work towards the clamping bolt/stud, not out from under the clamp. Minimize the protruding length of thread past the clamping nut, if necessary using sacrificial bolts or studs you can cut to length, or even using a long M8 stud for one of the faceplate mountings, so you can get a clamp nearer to the faceplate center. Double-check all clamps are secure, manually turn the faceplate to check the work and clamps clear the ways, top-slide and toolpost, and stand out of the 'line of fire' (a disc extending from the faceplate) when spinning up the work for the first time. <br />
<br />
If you need to machine close to a clamp, consider marking a safe limit circle on the faceplate and work with a marker pen to make it easier to see how close the cutting tool is to crash disaster. <br />
<br />
I strongly advise reading chapter two of Tubal Cain's book "Workholding in the Lathe" several times before your first faceplate setup, and if possible get another experienced lathe user to check your first few setups before spinning them up.<br />
<br />
==== Chuck Guard Removal ====<br />
The faceplate is too large diameter to fit under the chuck guard, but the guard has an interlock switch wqhich must be closed for the lathe to run. The guard is now fitted with wing nuts so it can be removed allowing the the interlock switch to close when using the faceplate. It *SHOULD* *ALWAYS* be refitted if a chuck is fitted, except when turning work too large to clear the guard. <br />
<br />
''The chuck guard is primarily there to make it very difficult to start the lathe without removing the chuck key and to reduce the area of large diameter spinning surface exposed. It may slow down the projectile if a chuck sheds a jaw but is unlikely to stop it. Also it serves to contain coolant spray spun off the chuck. As we don't use flood coolant this usually isn't an issue for us. As setting up for faceplate work doesn't use a chuck key, and the most hazardous zone is the face of the faceplate, with its spinning projecting clamps, with full access required for machining operations, which a guard would not cover, the consensus is that removing the guard is an acceptable risk.''<br />
<br />
=== Turning and Facing ===<br />
We are getting good results in aluminium, brass, and even steel using HSS cutting tools in quick-change tool holders, and the ~ 94 um/turn power feed. Unfortunately due to lack of rigidity in both the machine and smaller diameter parts, if you don't want the outer end to be over diameter, a light final cut and multiple 'spring' passes will probably be required.<br />
<br />
For aluminium, a sharp HSS tool and 0.5 mm (20 div) depth of cut gives good results with power feed for rapid stock removal. Its also easy maths as each cut takes ~ 1 mm off the diameter. Finish cuts should be much finer, 0.1 mm (4 div) is 'in the ballpark'.<br />
<br />
For steel, using carbide insert tooling, a 0.25 mm (10 div) depth of cut is more appropriate, and with pre-applied cutting oil, gives reasonable results with power feed if you use enough speed. The maths is not quite so easy as you are only taking 0.5 mm off the diameter per pass. Again, use finer finish cuts but try to plan your cuts so the final cut is still cutting, not smearing the surface!<br />
<br />
When facing or parting off, some skill is required to turn the cross-slide handwheel steadily to get a decent finish and to avoid shock-loading the tool tip. Increasing the spindle speed in one or more steps to keep up with the reducing diameter is advisable, but avoid speeds that cause resonances (resulting in chatter). When parting off, small through-hole parts may be caught on a thin rod chucked in the tailstock, and pre-positioned inside the work with its tip right up to the parting off position.<br />
<br />
==== Using the Steady Rests ====<br />
For the fixed steady rest, see Blondihacks' Lathe Skills #26 - How To Use a Steady Rest! [[#Youtube_Playlists_&_Videos|{below}]]<br />
<br />
Ours doesn't have ball bearing fingers, so a smooth surface on the work and adequate lubrication are essential. The thumbscrews can only tighten the fingers, so for small adjustments outwards you need to either slack off the clamping nuts or ease them slightly and use a drift against the back of the finger's slot. Once set, check the chuck still turns freely.<br />
<br />
The traveling steady rest needs to run on a machined surface, so at least for the first pass, must follow the tool, so its difficult to avoid using more compound slide overhang than is desirable. An initial surface should be cut next to the chuck or tailstock center before fitting the steady rest.<br />
<br />
Both are a PITA to fit - the fixed one has to have its clamping post inserted up through the bed, and the supplied spanner is useless near the headstock, and the travelling one's mounting holes on the saddle almost invariably need swarf picked out of them.<br />
<br />
==== Turning Between Centers ====<br />
<s>Using a MT3 to MT2 reducing sleeve, the MT2 dead center can be fitted in the spindle.</s> ''Currently the MT3 spindle taper is compromised.'' Alternatively, a soft center can be turned immediately before use in the three jaw chuck, but that must have its 60° point re-cut to concentric if the chuck is disturbed, and needs to be either large enough to bear on the chuck body, or must have a lip to bear on the end face of the jaws to take the axial thrust. Recutting the center is a PITA, as the compound angle must be set to 30° anticlockwise, then reset to a true 0° afterwards. Maybe a right-hand 30° end angle zero rake form tool is the answer, or use the carbide insert tool SSKCR0610H06 as a form tool with the toolpost rotated 15° anticlockwise.<br />
<br />
With the MT2 live center in the tailstock quill, this gives us a center either end of the work to hold it.<br />
<br />
We also need a drive dog similar to [https://littlemachineshop.com/products/product_view.php?ProductID=4473&category=1 this], and the corresponding drive post to bolt to the spindle nose. I have some 25mm bore thick wall iron pipe, which should do nicely. Lengths of the dog's straight tail and of the post TBD after I check how much the center protrudes. N.B. its recommended to tie the tail to the post to keep them in contact so they don't slam. ''Currently we will need to drive from the chuck jaws. Possibly use the exterior jaws with a short soft center gripped on the inside end and drive from the highest step.''<br />
<br />
=== Drilling ===<br />
Always start with a center drill so deflection of longer bits doesn't start the hole off-center. For larger bits (> 5 mm), first drill to the web size, then to final diameter. For a precision hole, drill slightly undersize and ream to final diameter. ''Supply your own reamers!''<br />
<br />
Caution: See note about the quill anti-rotation pin in section [[#Tailstock Quill|Tailstock Quill]] above.<br />
<br />
=== Boring ===<br />
Caution: As the spindle doesn't extend right through the headstock housing, if boring in a through hole, chips tend to fall out the back and tumble in the spindle bore till they fall into the change gears. To avoid this, one should plug the spindle bore with a wad of paper towel or rag and when cleaning up afterwards, use a rod to push it through towards the tailstock, with the chuck jaws (if fitted) wound clear of the spindle bore.<br />
<br />
A swivel bladed hole deburring tool (pale blue handle) can be found in the main room on the windowsill behind the drill press.<br />
<br />
A couple of boring jobs have been bodged with an awkwardly angled turning tool and achieving acceptable effective rake with enough clearance to reach deep enough into the hole has been problematic. I reviewed the tools we had and found none suitable for starting out in a 13mm bore, the max diameter we can (easily) drill. I therefore decided to buy a set of boring bars and make a holder for them. I had difficulty finding anything affordable under 10mm shank - the best low cost option was a [https://www.amazon.co.uk/dp/B07P5LGVBX set of nine 3/8" (9.525 mm) shank brazed carbide tipped boring bars], which would be close to the max capacity of the quick change boring bar holder - if we had one! Unfortunately this holder for our specific toolpost is difficult to find except in a toolpost bundle. Another annoyance is the variable tip height of the set, varying from 1.8 mm to 2.8 mm above the center of the shank.<br />
<br />
I therefore decided to make a boring bar holder of the [https://littlemachineshop.com/products/product_view.php?ProductID=1700 Littlemachineshop.com (USA) style] for use in the four way toolpost, as the additional rigidity will certainly help. Starting with a slightly over 50 mm length of 16 mm aluminium square bar and using the four jaw chuck , both ends were faced and an attempt was made to find its center and center drill it. It was then drilled out to ~9.8 mm after much drama due to blunt drills and drills that cut ~1mm oversize. Too big, but beggars cant be choosers as we didn't have a boring bar holder or a 3/8" reamer. Unfortunately the final hole ended up significantly off center. It was then chucked crossways and ~1 mm skimmed off its thickest side to gain clearance to allow it to be shimmed to height, then one side was slit lengthwise manually with a hacksaw.<br />
<br />
It was fitted to the for way toolpost and loaded with a booring bar, which clamped firmly. A 0.86 mm shim stack brought the tip of the largest boring bar almost spot on center height, with the difference easily accommodated by twisting the tool slightly. The three jaw chuck was then remounted, and a piece of iron pipe chucked for a test. It cuts well and leaves a decent surface finish.<br />
<br />
''The boring bar setup is a work in progress - talk to me before attempting to use them if you have a project that would benefit from boring..''<br />
<br />
ToDo: get something that can sharpen tools tipped with this grade of carbide - it needs some sort of diamond (or possibly CBN) wheel as green grit silicon carbide does little more than polish it. ''N.B. diamond wheels are rapidly eroded by grinding steel, so the supporting steel seat must be undercut with a regular grinding wheel before the diamond wheel can contact it.'' <br />
<br />
We'll also need 50 mm square sheet shims to fit under the toolpost to gain clearance in the toolpost above the tool or toolholder. A 2.4 mm shim would give us about the same above and below spindle center height, and we probably need a small selection of thinner ones.<br />
<br />
=== Thread Cutting ===<br />
The objective is to cut a thread that complies with the ISO metric thread profile. Our lathe is not currently equipped to cut non-metric threads, (with the exception of BA which have pitches based on metric threads of that era).<br />
<br />
[[File:ISO and UTS Thread Dimensions.svg|frame|center|Metric Thread Profile - from the geometry, H is ~86.6% of P]]<br />
<br />
Metric thread data - See 'Preferred Sizes' at: https://en.wikipedia.org/wiki/ISO_metric_screw_thread<br />
<br />
See "Mini Lathe User’s Guide" section '''Threading''' for general techniques *ONLY*, and above for change gears and threading dial setup.<br />
<br />
Amadeal specify the max. thread pitch as 2.5 mm. Any thread pitch greater than 1.5 nn requires the change gears to gear up. When gearing up it is desirable to distribute the ratio as evenly as possible over the two pairs of gears in the geartrain to avoid excessive tooth loading.<br />
<br />
==== External Threading ====<br />
Initially turn work to required Major Diameter, set up change gears and threading tool, touch off on the work, zero the top and cross slide dials, and do a 'scratch' pass to check the pitch. Back off the tool, return the carriage, and re-engage the half nuts on a valid dial line clear of the end of the thread then immediately stop the lathe, and hand turn the chuck till the tool tip is (hopefully) over the scratch to check the thread pickup. If all is good, return the carriage again, restart the lathe and start cutting your thread. <br />
<br />
Methods of doing so vary depending on the size of the thread and toughness of the metal, but straight-in plunge cutting is generally to be avoided as has the highest cutting forces, and does not reliably keep the carriage (and top-slide if set parallel to the work) loaded to avoid pitch errors due to backlash. <br />
<br />
If leaving the half-nuts engaged and reversing the lathe to return to the start of the thread for the next pass, its absolutely essential to back the tool out of the thread for the return pass as it will not follow the path of the cutting pass due to backlash in the geartrain, leadscrew mounts and half-nuts.<br />
<br />
==== Internal Threading ====<br />
''<nothing here yet>''<br />
<br />
== Cutting fluids ==<br />
=== Why bother? ===<br />
[https://youtu.be/mRuSYQ5Npek Watch this video] and contemplate what's actually happening to that thin ribbon of metal being removed. Most of the lathe's motor power is being turned into heat by internal friction in the chip being removed in the zone around the cutting edge, and surface friction at, and immediately behind the cutting edge, near-instantly heating the chip by up to several hundred degrees. Reducing the surface friction using a suitable cutting oil reduces the strain on the machine as a whole, and reduces workpiece and tool heating (and thus expansion) with consequent improvements in maximum usable feed and depth of cut, surface finish and accuracy. It also drastically increases the life of the cutting edge.<br />
<br />
=== Practicalities === <br />
We don't have a coolant system for the lathe and *really* don't want the maintenance hassles of using soluble cutting oil/coolant as if used infrequently its a PITA to keep recirculated high water content cutting fluids from going rancid and stinky, and they can also rust the ways, so even a total loss gravity feed system is problematic. Therefore if dry machining doesn't give a good enough finish, we tend to use oil applied topically, by hand to the work. <br />
<br />
* Hard brass is typically free-turning without oil, however some light oil for the final cut can improve surface finish, but with the disadvantage that it will increase loose chip buildup on the tool as hard brass typically forms short spalls or splinters rather than curly chips.<br />
<br />
* Many Aluminium alloys tend to be gummy, and Paraffin or other mineral spirits mixed with a little oil can help prevent the aluminum welding to the tool edge. WD40 will do at a pinch, but its messy to apply from a spray can.<br />
<br />
* Steel really needs *GOOD* cutting oil. Lard oil is the traditional choice for steel. If there are any objections to lard oil, we should bite the bullet and get some commercial dark high Sulphur cutting oil, but beware, many such oils use an additive package that includes lard oil.<br />
* Cast iron (except ductile) should be cut dry, as the carbon micro-inclusions self-lubricate it, and the carbide in the dust (primarily Cementite) are very abrasive, so tend to form a grinding compound if mixed with oil. <br />
<br />
I've sorted out an oil pot lid with a 1/2" brass collar soldered in to give a nice smooth sided hole, for ease of use and to minimize the risk of spills when using a brush to apply cutting oils, and got some dirt-cheap brushes. It fits Shippam's paste (and similar own-brand spread) jars and I've found several jars and ordinary lids to seal them for storage. Unfortunately it isn't the easiest to get this type of jars' lids back on square so they seal properly, and if you over-tighten them and there's a temperature change, they can be a total <expletive> to reopen. Using the rubberised handles of a large pair of pliers to grip the jar lid just above its rim is the best option, and avoids damaging the lids.<br />
<br />
''N.B. For the smaller brushes, the glue holding the bristles in is attacked by paraffin. To prevent loss of bristles, crimp the aluminium ferrule of each new brush of this type before use.''<br />
<br />
We have, in labelled jars:<br />
<br />
* Sulphurised Lard oil thinned with paraffin. Best choice for heavy cuts and threading in steel but stinky.<br />
* Lard oil thinned with paraffin. Good for steel and acceptable for softer copper alloys<br />
* Paraffin with a trace of light oil. Good for aluminium, and can help prevent squealing chatter on finish cuts in brass.<br />
<br />
I've also got some paraffin wax (in the form of a stubby candle), which can be applied lightly (under power) to brass and aluminium stock especially on the finish pass. It makes less mess than oil but unfortunately tends to build up on the tool tip, making it difficult to 'work by eye' without frequent pauses to clean the tool tip.<br />
<br />
We've also got a tin of [https://www.rocol.com/products/rtd-compound Rocol RTD cutting compound], which is a thick paste. Its highly recommended for drilling and tapping steel (in the drill press or by hand), but as a paste, is less useful for general lathe work unless thinned to a fluid consistency, e.g. with paraffin or white spirits. OTOH its certainly worth trying for high speed facing steel as it is less likely to get flung off.<br />
<br />
== Cleaning and Maintenance ==<br />
Swarf is a significant cut hazard to the operator, especially stringy swarf from cutting steel. Never touch it bare-handed - always use a tool e.g. a brush, or a hook, or needle nose pliers for grabbing long swarf.<br />
<br />
* After use, brush all swarf off the toolholder, compound and cross slide etc. ways and leadscrew. Ian B has blocked off the opening at the headstock end of the rear splashguard (to try to keep swarf out of the motor), so one must sweep the swarf towards the open tailstock end and catch it in a dustpan or similar. Preferably, also thoroughly clean out the chip tray under the lathe, but at least sweep out visible swarf.<br />
* Wipe up any cutting fluid residue and re-lubricate affected sliding surfaces with way oil.<br />
* Do not solvent clean the chuck guard, as it will make the plastic brittle, or even craze it. Water with a little detergent is permissible for cleaning it, with the guard totally removed from the lathe.<br />
<br />
Before engaging the half-nuts for power feed/threading, check the leadscrew is clean! ''Best cleaned under power, with a toothbrush.'' <br />
<br />
'''Caution:''' The traverse gears behind the carriage handwheel are in an open-backed housing and tend to become packed with swarf! Swarf buildup here will result in jerky carriage movement. Clean out as much as you can with a toothbrush ...<br />
<br />
===Lack of lubrication and/or swarf or dirt build-up can be disastrous===<br />
* If using the change gears/power feed, lack of lubrication of the B-C stub shaft center pin or either leadscrew end bearing can result in seizure and immediate destruction of one or more gears in the gear train or worse. <br />
* Small pieces of swarf can get between the saddle and ways, or into the slides degrading accuracy, possibly permanently if hard swarf scores them, or jamming them. The carriage handwheel gears behind the apron are notorious for accumulating swarf, and swarf buildup on the leadscrew can prevent the half-nuts engaging properly, resulting in scrapped work, and possibly stripped half-nuts. <br />
* Metal swarf can get into the motor (''though Ian B has modified the rear chip catcher to reduce the risk)'' or into the control box via the leadscrew, and short-circuit stuff. At best it will blow the fuse and need a strip-down to clean it out, at worst it may require a replacement [https://www.amadeal.co.uk/acatalog/Speed-Control-Circuit-Board--12amp-AMA_SP_CJ18_SCB12.html#SID=12 speed controller] ''(currently £96)'' and/or [https://www.amadeal.co.uk/acatalog/550W-motor-for-CJ18A-Mini-Lathe-467.html#SID=240 motor] ''(currently £105)'' and possibly other electrical parts. We should probably fit a [https://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C3-Mini-Lathe-Spares/C3-256-Leadscrew-Grommet-Dustproof-Cover C3-256 Leadscrew Grommet] to keep swarf out of the control box, as it tends to drop onto the 'Filter' board which is mounted horizontally, below the leadscrew.<br />
* Grit from grinding, sanding etc. forms a grinding paste with the way oil, and will rapidly wear out the ways, saddle and slides. Keep grit off at all costs e.g. by covering the ways and slides during grinding/sanding operations, and if there's any chance grit has gotten where it shouldn't, clean and re-lubricate *BEFORE* moving the carriage or slides, then move the carriage and slides, wipe down where they were with a clean paper towel and check there's no remaining traces of dirt other than clean way oil on the paper towel. If it doesn't come clean when you re-lubricate and move it again, a full strip down may be required to solvent clean and relubricate the precision sliding surfaces.<br />
* Although a metalworking lathe *can* be used to turn hardwood, wood dust and small chips are extremely pernicious, as they get everywhere, even clinging to clean surfaces, are abrasive due to their silica content, and are hygroscopic, promoting rust. An even more thorough clean-up than after using abrasives is needed, immediately afterwards. Oily wood dust and fine wood chips in significant quantities are a fire hazard, even in the trash bin.<br />
<br />
===Lubrication===<br />
See section: "Lubrication" in LittleMachineShop.com "Mini Lathe User’s Guide" [[Ian_M's_Lathe_Notes#Manuals|(below)]]. As we usually only open two nights a week, in the table on page 16, Daily lubrication becomes Weekly and Weekly becomes Monthly.<br />
<br />
===General Maintenance===<br />
* The grubscrews holding the cross-slide and compound slide dials tend to loosen due to vibration and use of the dials. Keep them snugged up, but not so tight the dials cant be set without an Allen key.<br />
<br />
* The screws holding the cross-slide nut tend to work loose due to vibration. Crank the handle to and fro through the backlash and visually check there is no movement of the screw heads in their holes. If there is, see the [[#Excessive_cross-slide_backlash|notes below]].<br />
<br />
===Removing the Carriage===<br />
Its possible to remove the carriage from the bed for cleaning etc. without dismantling it. The only stop to its motion is the righthand leadscrew bearing.<br />
<br />
Start by removing the tailstock. Crank the carriage to the tailstock end then remove the leadscrew bearing (two screws and a nyloc nut on the leadscrew end). With the half-nuts open, hold the leadscrew centered in them and crank the carriage off the end of its rack, then slide it off the end of the bed.<br />
<br />
Refitting is the reverse of removal, except (if its gibs are correctly adjusted) the carriage will be very tight on the end of the bed ways so may be difficult to work onto the ways without a stack of blocks of wood or similar to support it at exactly the right height. The righthand leadscrew bearing must be refitted with the carriage as close as possible to it and the half-nuts firmly closed to support the leadscrew at the correct height to hold it in alignment while the screws are being tightened. The nyloc nut controls leadscrew end-play. Fully tighten it then back it off slightly till the leadscrew turns freely with its change gear removed.<br />
<br />
If the Apron has been off, refit it with the screws no more than lightly finger tight and only finally tighten them after checking lead screw engagement at both ends of the carriage travel and that the rack and pinion operates smoothly over the full travel.<br />
<br />
== Issues and Annoyances ==<br />
As of September 2023 - mostly resolved, apart from the spindle bearings and runout, the lathe is in better condition than it has been for a number of years.<br />
<br />
===Four Jaw Chuck has two jaws too tight===<br />
Fixed 27/10/2023: The grooves in the opposite sides of the jaws that run in the chuck slots were slightly out of true, and the rails either side of the slots were slightly too thick towards the center. Due to the difficulty of seeing the high spots, after cleaning up and deburring the jaws didn't do enough to ease them, I decided to grind the top of the rails where they were binding. Several repetitions of spotting, grinding then diamond filing the high spots has eased them enough. I cleaned everything, greased the jaw slides and screws, and refitted the studs so the chuck is now fit for service. <s>Two of the chuck jaws are tight in their slots, making precise adjustment difficult due to lack of 'feel'. Moving the jaws round the slots shows the problem follows the jaw not the slot, and stoning various edges hasn't helped so it seems that the affected jaws are slightly oversize. Need Engineer's spotting blue to determine which of the sliding surfaces is binding, so we can see what needs scraping/stoning/grinding to fix them</s><br />
<br />
''N.B. Don't move the jaws to a different slot - the formerly tight jaws *must* stay in the slots furthest from the makers mark.''<br />
<br />
===Excessive Runout===<br />
Mostly fixed 24/10/2022: I ground the chuck seating surface of the spindle nose (outside lip) to under half a thou runout. This also cleaned up several burrs. It would be possible to do better, but that would need good spindle bearings, and a more rigid toolpost grinder mount.<br />
<br />
Our spindle nose was damaged years ago by a person with little mechanical aptitude (who shall remain nameless) beating it up with a hammer mushrooming the spindle nose. We are getting several thousandths runout at the end of the MT3 bore, a MT3 to MT2 reducer sleeve in it runs visibly out of true, as does the spindle nose flange. When you put a chuck on it, the runout is magnified by the distance from the spindle nose. Ideally we would replace the spindle when we change the bearings but its £52 [https://www.amadeal.co.uk/acatalog/4-Spindle-Upgrade-Real-Bull-Mini-lathe-CJ18-series-AMA_SP_CJ18_003RB.html#SID=9 from Amadeal] and money is tight. It may well require more work after the bearing upgrade. Once good bearings are in, if we can borrow a decent MT3 arbour as a reference, we should consider skimming the bore.<br />
<br />
===Spindle bearings===<br />
* The spindle bearings appear to be close to worn out. They are notably noisy when running, and there appears to be more slop in the spindle than is desirable. We have some ideas for possible replacement/upgrade, but it requires a major teardown.<br />
<br />
: The original bearings are allegedly 6206-2RS or 6206-ZZ deep groove ball bearings - 2RS codes rubber seals both sides and ZZ codes metal shields. Although the deep groove gives reasonable ability to withstand axial loads, the bearing balls point contact means they are vulnerable to [https://en.wikipedia.org/wiki/Brinelling brinelling] due to shock loading. The jammed on three jaw chuck didn't help this, as before we skimmed the spindle nose lip, it had to be driven off using a bar through the spindle bore, shock loading the bearings every time. Also even a minor 'crash' could have brinelled them due to eccentric shock loading, and the lathe has previously been crashed badly enough to need drive gear replacement. There are also issues with the 'approved' method of spindle and bearing removal from the headstock brinelling them, even if you don't abuse the spindle nose with a hammer!<br />
<br />
: A possible replacement is 30206 tapered roller bearings. The new bearings are slightly thicker so the plastic spindle spacer (15) needs to be machined to length to get the 45 tooth spur gear that drives the change gears laterally aligned with the tumbler gears. If a temporary replacement (3D printed?) is fitted, the lathe can be run (without power feed capability) so this can be done on the lathe after fitting the new bearings. As tapered roller bearings have line contact, they are significantly more resistant to brinelling.<br />
<br />
: ''See [[Talk:Ian_M%27s_Lathe_Notes]] for notes, links etc. for this upgrade.''<br />
<br />
===Motor stuttering===<br />
* Fixed 21/09/2023: The motor was running very erratically and it was very difficult to set a speed. Several loose connections were found in the control box, mostly loose female spades to the motor controller board, but also a dry jointed braking resistor on the 'Filter' board, and an inhibit wire completely off its terminal on the forward/reverse switch, making intermittent contact. After tightening and/or remaking all affected connections, it was much improved but still not right below 300 RPM. The remaining issues were due to poor wiper contact in the speed control pot, and stripping it, cleaning the track and contact ring and re-tensioning the contacts resulted in the motor now running smoothly over the full speed range. The speed is slow to settle, and while part of that is probably the lag in the digital tach, I suspect that the KBIC motor speed controller isn't properly tuned as it was (allegedly) previously replaced.<br />
<br />
===Drive belt slipping===<br />
* Fixed 28/9/2022: During testing the motor after the above issue, it was noted that the chuck could be stalled, slipping the drive belt, with not much torque. The drive belt was determined to be loose and a bit worn, but still in acceptable condition. <br />
<br />
: Access for servicing the belt requires removing the control box ''(2 spades to ZVR switch disconnect the supply, speed sensor and motor simply unplug from the 'filter board')'', the motor cover, chuck guard switch assembly + wiring cover, the change gear 'A' (drive) shaft carrier assembly, and the tumbler gear assembly. See https://youtu.be/EkxlIz01BdA for disassembly/reassembly, though on our lathe, the speed encoder ring on the spindle prevents the belt cover from being fully removed without disturbing the spindle nuts. There is enough room to work with it loose, but still trapped by the encoder ring. Also, unlike the video, if the 'jack' screws under the headstock are correctly adjusted, and the studs aren't excessively bent, there is no need to make custom studs. <br />
<br />
: It turns out that our lathe was missing the M6 hex headed jack screws that press the motor down to resist the belt tension, and the motor had cocked out of position at a severe angle. I know Ian B had had considerable trouble adjusting it after the motor fault back in October 2022, and I believe it had been getting slowly worse ever since. The jack screws were probably mistaken for headstock fixing bolts during disassembly after the crash that resulted in the metal Hi/Lo gears being fitted, then lost. The penny washers on the studs had dished, so I turned them over and backed them up with smaller washers and switched to nyloc nuts so they cant back off due to vibration. N.B. there is a packing washer on the motor side on one of the studs, presumably so the shaft is true to the ways. Adjusting the motor is awkward to say the least. One has to slack the stud nuts off a lot, pry under its rear end to lift it enough to be parallel to the ways, snug the stud nuts, check alignment, then set the jack screws and their lock nuts to hold it there, and finally tighten the stud nuts. <br />
<br />
: Tension: According to Sieg, it should be possible to twist the belt 90° mid span with a light finger grip. Other sources say 1/32" - 3/32" deflection mid span with light finger pressure.<br />
<br />
===Speed display blanking===<br />
* The speed display has been intermittent, blanking and flashing 8888 and 0 at certain speeds for as long as I have been using the lathe. Finally on 18/07/2022 it failed completely, with no display. I removed the display module and bench tested it - the pins are labelled 5V GND PL PE, PE is frame ground and PL is a TTL level pulse from the speed sensor - confirming that it was in good working order. My suspicions then turned to its power supply on the 'Filter' board. With both the sensor and display unplugged, the 5V rail was found to have a only a couple of volts, but the unreg DC was 17V and stable. Replacing the 78L05 5V regulator restored the 5V rail and normal operation.<br />
<br />
: ''I conclude its been failing for a while with high load current due to speeds with more lit segments causing it to drop out, resetting the speed display, causing it to blank, lowering the current enough for the regulator to recover, then the display MCU lamp tests (8888) then re-acquires the speed, repeating ad-nauseum till the speed is changed. I don't like the design as the high input voltage results in excessive dissipation.'' <br />
<br />
: ''ToDo: Bench test display to measure its worst case current consumption, then fit an appropriate dropper resistor to reduce the 78L05 dissipation.''<br />
<br />
===Quill spinning when drilling===<br />
* The quill was tending to spin while drilling because its anti-rotation pin (a M5 dog tip setscrew) was sheered. I've removed the debris, aligned the scale with the top of the tailstock and fitted a longer M5 dog-tip setscrew to replace it, with a nut to lock it at the correct height. N.B. the pin isn't that 'meaty' so if using big drills in tough metals, to prevent shearing it, it should be backed out so the quill can be turned by hand and unwanted rotation controlled by being quick with the quill lock if it starts to spin, or even using a close fitting rod in one of the chuck key holes with plastic tube over it to protect the ways. <br />
: ''If the screw sheers again, the quill will need to be removed and the tailstock taken off the lathe so the sheered tip can be shaken out, and if the setscrew is difficult to remove it probably means the threads are mangled where it sheered. Try driving it right through with the quill out.''<br />
<br />
===Sloppy quick change toolpost locking mechanism===<br />
* Once the dovetail clamp screw was slackened, there was nothing preventing the dovetail twisting or cocking significantly, and friction with the toolholder made it tend to do so, making toolholder insertion and removal more difficult unless the clamping screw was backed off excessively. I added a compression spring around the clamp screw inside the toolpost to push the dovetail outwards so it mostly retains alignment when open, allowing toolholders to slide on or off cleanly with far less screw slackening.<br />
<br />
===Leadscrew rubbing===<br />
* The leadscrew shaft is rubbing on the insulating separator inside the control box. Unfortunately the corner of the relay on the Filter Control Board (#160) doesn't allow enough clearance. Although the friction isn't much of a problem at high reduction ratios, e.g. 16:1 power feed, it increases the stress on the change gear train, and may be problematic when threading at feeds above 1:1. ''Possibly pack out the control box mountings by a couple of mm.'' <br />
<br />
===High/Low lever backwards!===<br />
* The high-low drive gear selector behind the headstock is incorrectly labelled and differs from the manual: low gear (which we normally use) is with the lever towards the tailstock. ''I suspect that the gears in the headstock were refitted the wrong way round when it was upgraded to metal gears.''<br />
<br />
: ''ToDo: Get it reassembled the right way round during the spindle bearing upgrade!''<br />
<br />
===Carriage lock fouls top slide===<br />
* The T handscrew has been replaced with a M5 hex headed bolt, to permit access when the top slide is over it. An 1/4" drive 8mm socket is usually left on it, but needs to be removed when the full cross slide travel is needed. The small (4 jaw) chuck key is near enough 1/4" to use for it. If you need to (un)lock it while the compound is over it, you'll need an 8mm spanner. ''The [https://www.amadeal.co.uk/acatalog/Mini-Lathe-Carriage-Lock-463.html Amadeal lock screw] is in the spares tin as it was too high and fouled the compound slide.''<br />
<br />
===Tailstock locking lever loose===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock - See full image for key to screws]]<br />
* Diagnosed and fixed 10/1/2023 - In the base of the upper section of the tailstock, there are two dog tip set screws that engage with locating grooves in the counter-rotating shafts carrying the eccentric locking cams. They'd backed off, probably due to vibration. They need to be tightened till they bottom out in the groove, making sure they are '''in''' the groove, backed off half a turn so the shafts can turn easily, and locked in place. There's no facility to do so, so reassemble with weak threadlocker. Unfortunately to get to them you have to remove the tailstock base slide, which is held on by the pressure of four adjusting grub screws, which all need backing off, and one socket headed bolt from underneath so full tailstock realignment is required after reassembly, which even for a rough alignment is tedious.<br />
: <s>The tailstock locking lever is loose and can be pulled out on its axis. It works OK when fully pushed home but needs investigating. ''I tightened the grub screw as the lever was coming off its shaft, but the whole shaft pushes/pulls in and out. It works OK fully pushed in, but it seems something that is meant to retain it has failed inside the tailstock base.</s><br />
<br />
===Gear alignment issues===<br />
* Change gear alignment is poor. I've currently got a gapped washer (to clear the key) packing out the A shaft so the gears line up, but this reduces the key's engagement so is problematic due to the high loading if the gears are set up for coarser threads. <s>Also I need to turn down some penny washers to slightly less than the root diameter of the metal 20T pinions, as gear retaining washers.</s> ''The gear retaining washers for A gear and B-C stub shaft are now done, turned down to slightly under 16 mm dia. Spares in the change gear tin. ToDo: The D (leadscrew) washer requires a larger center hole, so make two more with that hole.'' <br />
<br />
===Saddle gibs loose===<br />
* Fixed 11/04/2023: I took the apron off for access (and to clean the carriage handwheel gears), and found the front sheer plate screws were completely loose. I've snugged them up some and set the opposing grub screws and got a lot of the slop out. I've re-checked the front ones, and taken up the slop in the rear ones - Unfortunately it wasn't possible to get carriage movement to have an even 'feel' over its whole travel, and its noticeably tighter near the tailstock. If light hand pressure on the side of the unlocked carriage can cause movement (with the half-nuts open), its time to readjust them again, though it should be possible to move the carriage with a firm push. <s>The saddle gibs (actually the sheer plates) were too loose, to the point that engaging a slightly stiff threading dial could cause it to self-feed, an obvious crash hazard if working near the chuck or a step in the work.</s><br />
<br />
''N.B. the lefthand front opposing grubscrew is short, (fully recessed) and unlike the others does *NOT* have a locking nut as it must clear the traverse pinion. A wrap of PTFE tape provides enough friction to keep it in place, though possibly a bit of nylon fishing line down its hole would be better.''<br />
<br />
===Excessive cross-slide backlash===<br />
* ''Mostly Fixed <s>11/10/2022</s> again 07/11/2023:'' The cross-slide screw had excessive backlash (nearly three turns), possibly due to end float, which increases the risk of loosing track of the cut depth during threading operations. If you ended up off by a turn too far in, a crash was the most likely outcome.* 02/11/2023: The backlash is back up to one turn. I suspect the cross-slide screw nut mountings are working loose again.<br />
<br />
: So it turned out that the reason the cross-slide had nearly 3mm of backlash wasn't end float, it was loose cross-slide screw nut mountings. The nut has two socket headed cap screws pulling up, one either end, accessible from the top of the cross-slide, which control the tilt of the nut to take up backlash in the nut, and an opposing grub screw pressing down on the center of the nut to make it longitudinally rigid. I gambled the cap screws weren't too far out and snugged up the grub screw, and that immediately took out over 95% of the backlash which is now down to 10 divisions or so, or 0.25 mm. Shimming the cross-slide screw collar should take out some of what's left and careful adjustment of the nut tilt should get that down to under 0.1mm.<br />
<br />
: 07/11/2023: When the problem recurred I investigated further . It is difficult to get the cross-slide nut aligned correctly as it must be at the same height as the screw which is constrained by the bearing surfaces in the bracket. With the cross-slide almost at the front limit of its travel, I removed the screw and set the nut as level as possible and visually centered in the bore, then re-fitted the bracket and screw, then adjusted the tilt till it turned freely through the backlash. I then tilted it up at the front till some drag was felt to minimise the backlash and tightened the screws to lock it in place balancing them to maintain the same feel as I tightened them. The result was 7 divisions of backlash, acceptable but not great. During normal turning operations, the load on the nut is tension on the front screw and pressure on the grubscrew, so if it slackens again due to vibration from chatter, odds are it will be the rear screw that's loosened. <br />
<br />
* Further reduction of backlash: https://youtu.be/Wu_tI29JL2Y?t=163 <br />
: Brass tinned with Pb-free solder to form a white metal bearing surface should work at least as well as the bronze used in the video. The shim washer needs to be 10 mm ID and ~14 mm OD. It isn't necessary to remove the lead screw from the cross slide, as the washer can be fitted in-situ with only the bracket removed. Its also possible to closely estimate the required washer thickness from the backlash - note the number of dial divisions of backlash, then strip down the dial and bracket and with the gibs tight enough to keep the cross-slide from moving, push and pull the screw to assess its end float. A dial indicator mounted on the cross slide probing the screw flange will give you the total end float. Subtract the end float from the backlash, than take off another thou (0.025 mm) for running clearance to get the washer thickness (assuming it seats fully in the recess). If after fitting it, snugging up the bracket screws makes the screw too stiff to turn, the washer is too thick - either make another one or try to lap it down.<br />
: TLDR: measure flange on cross-slide screw and depth of recess in cross-slide bracket (behind dial) and machine a shim washer to take up nearly all the difference.<br />
<br />
===3 Jaw chuck didn't mount properly===<br />
* Fixed 7/4/2023 by grinding the spindle nose lip. The three jaw chuck can now be installed and removed by hand with no hammering. A test bar in it now has only 2 thou runout (TIR) at the chuck.<br />
: <s>The three jaw chuck and the faceplate aren't seating properly on the spindle nose. Its too tight on the register diameter of the lip. This results in grossly excessive runout, and also makes this chuck and the faceplate a PITA to fit or remove.</s><br />
: ''The spindle nose had been abused with a hammer (before my time) which mushroomed it and may have brinelled its bearings. See '''Excessive Runout''' and '''Spindle bearings''' above.''<br />
<br />
== Manuals, Books and other resources ==<br />
=== Manuals ===<br />
The [https://wiki.richmondmakerlabs.uk/images/a/a3/Lathe_InductionNotes.pdf RML CJ18A Mini-Lathe Induction Notes]. Your mandatory Lathe Induction will cover most of this but its good to be able to refer back to it.<br />
<br />
Official [https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Amadeal CJ18A Manual], or paper copy (less complete) kept on shelf above lathe.<br />
<br />
The [https://www.chesterhobbystore.com/wp-content/uploads/2022/11/Conquest-Super-Lathe.pdf Conquest Super Lathe manual] is considerably better than the Amadeal manual and is for a near-identical machine.<br />
<br />
The [https://littlemachineshop.com/images/gallery/info/minilatheusersguide.pdf Mini Lathe User’s Guide] from LittleMachineShop.com is even more comprehensive, going into its usage in some detail, with a proper TOC, and covers both US and Metric versions of Realbull Mini-lathes. ''The only fly in the ointment is the threading section assumes a US lead screw so change gear selections and threading dial divisions will not be correct for our lathe.''<br />
<br />
[https://www.arceurotrade.co.uk/machineguides/C3-Mini-Lathe-Dismantling-and-Reassembly-Guide.pdf Sieg C3 Mini-lathe Dismantling and Reassembly Guide] "A picture story book to help you dismantle and reassemble your Sieg C3 Mini-Lathe" ''It is similar enough to ours to serve as a maintenance guide, except for the electronics, spindle drive and other headstock innards.<br />
<br />
The motor controller is a clone of a [https://acim.nidec.com/drives/kbelectronics/-/media/kbelectronics/documents/dc-drives/manuals/kbic_manual.ashx?la=en KBIC® SCR DC Motor Speed Control]<br />
<br />
=== Books ===<br />
'''Metal Turning on the Lathe''', by David A Clark, Crowood Metalworking Guides, ISBN-13: 978-1847975232 [https://www.amazon.co.uk/gp/product/B00E78RKIG Kindle Edition (£8.99)]. ''A 'free' epub can be googled for, *NOT* linked here due to dubious legality.''<br />
<br />
'''[https://archive.org/details/03screwcuttinginthelathe Screwcutting In The Lathe]''', by Martin Cleeve (a pen-name of Kenneth C Hart), Workshop Practice series #3, ISBN-13: 9780852428382<br />
<br />
'''[https://archive.org/details/15workholdinginthelathe Workholding in the Lathe]''', by 'Tubal Cain' (a pen-name of Tom Walsh), Workshop Practice series #15, Argus Books, ISBN-10: 0852429088<br />
<br />
'''[https://archive.org/details/20metalworkandmachininghintsandtips Metalwork and Machining Hints and Tips]''', by Ian Bradley, Workshop Practice series #20, ISBN-13: 9780852429471<br />
<br />
'''[https://archive.org/details/38toolandcuttersharpening Tool and Cutter Sharpening]''', by Harold Hall, Workshop Practice series #38, ISBN-13: 9781854862419<br />
<br />
'''[https://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpaperT204.pdf Cutting Fluids]''', by EC Bingham, NIST Tech. Paper No. 204, 1921<br />
<br />
=== WWW resources ===<br />
==== Mini-lathe Specific ====<br />
There's a *LOT* of mini-lathe info online. Notable sites include:<br />
* http://www.mini-lathe.com/ - A major Realbull/Sieg mini-lathe resource.<br />
* http://mikesworkshop.weebly.com/lathe-modifications.html - many mods including carriage DRO autostop, and variable speed leadscrew motor drive, cross-slide motor drive, etc. He also has a page with a bunch of accessories, toolholders etc. - http://mikesworkshop.weebly.com/lathe-accessories-and-tooling.html<br />
* http://andysmachines.weebly.com/variable-speed-controls.html - Scroll down to the 'UPDATE' section for the schematic of a very similar SCR speed control board. It also has the schematic for an earlier version of the Auxiliary Control Board (aka: 'Filter' board).<br />
<br />
==== Forums ====<br />
''with publicly accessible archives''<br />
* https://groups.io/g/7x12MiniLathe - Mini-lathe specific, active<br />
* https://www.hobby-machinist.com/forums/mini-lathe-mini-mill-information.220/ - active<br />
==== Youtube Playlists & Videos ====<br />
* Blondihacks: [https://www.youtube.com/playlist?list=PLY67-4BrEae9Ad91LPRIhcLJM9fO-HJyN Lathe Skills] (playlist) - "This is an educational series to help you learn to use your metal lathe. Watch them in order for best results! Satisfaction not guaranteed, especially if you're a cranky sort of person."<br />
* Frank Hoose (Minilathe.com) has a couple of relevant Youtube playlists:<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn7ON0jGM5UbM-KZDT56MOIp Mini Lathe Operations]<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn4nGRZaVq3wTOlvZNOmdAZ2 Mini Lathe Overview]<br />
<br />
==== General Machining ====<br />
* https://www.machiningdoctor.com/ - "THE #1 MACHINING TECHNICAL HUB"<br />
<br />
==Projects==<br />
[[File:VESA mount.jpg|thumb|Machined VESA mounting plate (left) and plate from Dell monitor stand it must match (right). The translucent washer shows the size of the original center hole.]]<br />
* My first faceplate project was boring out the center hole in a VESA mounting plate to adapt it to fit onto a surplus Dell 1708FP monitor stand. The part was centered using the tailstock dead center engaging with its original center hole. I clamped the part with studs and penny washers on the driving side of two opposite corners, with cap screws in the next slot round to trap the corners under the clamping washers, then withdrew the tailstock and dead center. After machining out the bore, I used the tip of the tool, rotating the chuck by hand, to scribe a circle for laying out the bolt holes. I finished off laying out and drilling the bolt and locating holes by hand at home, fitted it to the stand, and mounted the 2nd hand LG 24" widescreen monitor.<br />
<br />
* Another ultimately unsuccessful project was fly cutting aluminum flat bar to thickness to make custom shims for the set of carbide insert tools, for the four way toolpost. The 8 mm shank tools need ~2.5 mm shim stacks, and the 6 mm shank tools need ~4.5 mm shim stacks. Ideally I'd machine single shims, but the only stock I've got handy cleans up to only 3.2mm, and some fine shimming may be needed to fine-tune the tool height.<br />
<br />
: After sorting out the clamps so they were no longer twisting the aluminum flat bar stock, and switching to the short 45° turning SCMT06204 insert tool in the four way toolpost, to improve rigidity and get a well controlled tip radius, the finish was much improved. I'm still having problems getting an even thickness and am getting approx. 0.05mm variation, I suspect due to the aluminium bar stock distorting due to internal stresses as its surface is cut away. ''ToDo: try supergluing the stock to the faceplate before clamping to further reduce chatter and stop the warping.''<br />
: Looking back on this project a year later, its fairly obvious that the thickness variation was probably due to faceplate surface runout due to the damaged spindle nose.<br />
<br />
* Raphael has been working on a steel rocket nozzle with some assistance from myself. We have set up the rough cut chunk of ~ 50mm steel bar, faced both ends (to 50mm length) and turned the OD to 49mm to clean it up. Its going to need through drilling, probably some boring, and quite a bit of detail work on the OD. It will then need to be transferred to a jig in the drill press vice to allow a pattern of angled traverse holes to be drilled with acceptable accuracy.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_Lathe_Notes&diff=17582Ian M's Lathe Notes2023-11-14T22:29:40Z<p>IanM: /* The Chucks */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br />
<br />
''Currently these notes are semi-organized and non-authoritative. As I become more experienced with the RML CJ18A mini-lathe, I'm cleaning up, extending and reorganising them. Some lathe operating experience is assumed. If in doubt, '''*ASK*''' me, Andy H<sup>*</sup> , Jonathan H or another experienced minilathe operator!<br />
<br />
''* Andy H should be asked (for an authoritative answer) any questions involving RML usage policies or acquiring tooling or materials through RML.''<br />
<br />
== The Lathe ==<br />
Our Facilities page [[Facilities#Lathe|has]]:<br />
<blockquote><br />
'''Lathe'''<br />
[[File: Lathe2.jpg |200px|right | Lathe]]<br />
In the kitchen. <br />
<br />
Marked as a CJ18A Mini-Lathe from [[https://www.amadeal.co.uk/acatalog/CJ18A-Mini-Lathe-7x14-Machine-100mm-3jaw-Metric-With-Metal-Gears-AMA_LA_CJ18_M_3_MGRB.html Amadeal]]<br />
[[https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Manual]] <br />
<br />
[[Media:Lathe InductionNotes.pdf| Induction Document]]<br />
<br />
Possible upgrades:<br />
*https://www.youtube.com/watch?v=GwT-JQLbNPA<br />
<br />
''Please do not use the lathe until you have received induction'' <br />
<br clear=all><br />
</blockquote><br />
Its a Chinese import 7x14 mini-lathe. The 7x14 refers to the maximum diameter and length of work, in inches and is only a theoretical measure of the working envelope as you loose length to the chuck + any tailstock tooling, and the diameter is over the bed, not the cross-slide. See actual specifications below. <br />
<br />
Most if not all Chinese 7x10 to 7x16 mini-lathes seem to be remarkably similar (not uncommon with Chinese products due to [https://www.bunniestudios.com/blog/?p=284 Shanzhai (山寨)] )<br />
and the OEM of our Amadeal CJ18A Mini-Lathe was probably [https://www.made-in-china.com/showroom/cheap-lathe Yangzhou Realbull Machinery Co. Ltd]. Very similar lathes are also made by [https://www.siegind.com/lathe-machine.html Sieg], but their lathes tend to be slightly less sophisticated than the equivalent Realbull models.<br />
<br />
''N.B. Many Sieg parts are known to have slight but critical differences from Realbull parts, so '''DON'T''' order Sieg spares for a Realbull lathe!<br />
<br />
== Key Specifications ==<br />
Amadeal says the CJ18A Mini-Lathe is a 7x14 model with:<br />
<blockquote><br />
* Power 550 W<br />
* Distance between centres : 350 mm<br />
* Swing Over Bed: 180 mm<br />
* Swing Over Cross Slide: 110 mm<br />
* Taper: MT3<br />
* Tailstock Taper: MT2<br />
* Chuck diameter: 100 mm<br />
* Spindle Speed: 50 - 2500 rpm ''(with digital readout)''<br />
* Spindle Bore: 20 mm<br />
* Cross slide Travel: 65 mm<br />
* Range of Metric Threads: 0.5 - 2.5mm.<br />
</blockquote><br />
* The lead screw is metric, pitch 1.5 mm.<br />
* The spindle center is 90.6 mm above the flat of the bed (measured).<br />
<br />
Even though the compound and cross slide handwheels appear to be calibrated in thousandths of an inch, as ours is a metric machine, they only approximate that. One turn of a slide handwheel is 1mm advance, and they have 40 divisions, so each division is 0.025 mm, (approx. 0.984 [https://en.wikipedia.org/wiki/Thousandth_of_an_inch thou]). Similarly, the tailstock quill advances 1.25 mm per handwheel turn, which has 50 division dial, giving the same 0.025 mm divisions, but only 4 turns per 5 mm. The carriage handwheel is awkward - it moves approx. 19.2 mm per turn, and doesn't have a dial scale.<br />
<br />
== Notable Accessories ==<br />
We have:<br />
* [https://www.amadeal.co.uk/acatalog/160mm-Face-Plate-for-the-4-Mini-lathe-AMA_AC_CJ18A_FP160RB.html#SID=129 160 mm (6 1/4") Faceplate]<br />
* 100 mm (4") three jaw self-centering chuck (OEM standard) 22.5mm bore, with inside and outside jaw sets<br />
* 100 mm (4") four jaw (independent) chuck with reversible jaws (8 TPI screws)<br />
* Tailstock drill chuck (max. 13 mm dia.)<br />
* Live center for tailstock (+ OEM fixed center) <br />
* Four way Tool Post (OEM Standard)<br />
* [https://www.amadeal.co.uk/acatalog/Quick_Change_Tool_Post_for_the_mini-lathe.html Quick Change Tool Post] + 3 tool holders<br />
* [https://www.amadeal.co.uk/acatalog/Fixed-Steady-for-Mini-Lathes-AMA_AC_CJ18A_FSRB.html#SID=145 Fixed Steady Rest]<br />
* [https://www.amadeal.co.uk/acatalog/Travelling-Rest-for-Mini-Lathes-AMA_AC_CJ18_TSRB.html#SID=144 Travelling Steady Rest]<br />
<br />
''You'll find all of the above on the shelf above the lathe, with the accessories in the wooden box, apart from the steadies, which live next to it. Change gears, spare parts, and most cutting tool tips/blanks are in labelled white rectangular tins behind the lathe.''<br />
=== Measuring Tools ===<br />
We have:<br />
* Various dial indicators - the one with the adjustable magnetic base stand is the most convenient for most lathe setup work.<br />
* 25mm micrometer (in little grey case)<br />
* Grey case containing set of measurement tools including dial calipers, micrometer, steel rule (metric & inch), engineers square, and a fish-tail gauge<br />
<br />
''We currently lack''<br />
* ''A tool height setting gauge''<br />
<br />
=== Hand Tools ===<br />
Some common tools needed for normal use are kept with the lathe, in or attached to the wooden accessories box:<br />
* 2 mm Allen key - adjusting cross-slide and compound gibs<br />
* 4 mm Allen key - quick change toolholder tool clamping screws + height adjust, tightening dials<br />
* 5 mm Allen key - four way toolpost tool clamping screws, engaging/disengaging threading indicator<br />
* 6 mm Allen key - locking/unlocking quick change toolholder<br />
* 8 mm spanner - locking carriage when 8 mm socket can't be used, locking gib adjuster nuts <br />
* 13 mm spanner - changing chucks, locking steady rest jaws<br />
* Very long needle nose pliers - for grabbing swarf safely, holding one end of emery cloth safely so you can keep your fingers away from the jaws, and extricating small objects from awkward places.<br />
<br />
== Change Gears ==<br />
[[File:BC puller 1.jpg|thumb|Custom puller for B-C stub shaft]] [[File:BC puller 2.jpg|thumb|Pulling the B-C stub shaft]]<br />
See "Conquest Super Lathe" manual ([[#Manuals|below]]), section '''4.7 Change Gears''', PDF pages 28-29, but see below for mesh adjustment. The LittleMachineShop.com "Mini Lathe User’s Guide" (also below) section '''Threading''' gives a far better explanation, with pictures and diagrams, but its for a lathe with a US 1/16 inch pitch leadscrew, not a metric 1.5 mm pitch one like ours, so you *MUST* ignore all the tables in that section, replacing them with metric mini-lathe (with 1.5 mm pitch leadscrew) equivalents. <br />
<br />
We have the following tooth count gears: 20,20, 30, 35, 40,40, 45, 50,50, 60,60, 80,80<br />
which consist of the OEM power feed gears + the metric change gear set. Apart from the metal 20 tooth pinions, they are all plastic, probably Delrin if the molded in 'POM' marking can be trusted, but possibly plain Nylon 6, and are metric Module 1.<br />
<br />
If we wanted to add the capability to cut US/Imperial threads we'd need to buy additional 55, 57 and 65 tooth gears, and possibly a 21 tooth metal pinion.<br />
<br />
CGTK's [https://www.cgtk.co.uk/metalwork/calculators/changegears/minilathe?gears1=20,20,30,35,40,40,45&gears2=50,50,60,60,80,80&gears3= Change Gear Calculator] ''(link preloaded with our gear list)'' is useful if you don't want to calculate the ratios from first principles. Not all suggested combos will physically fit.<br />
<br />
* Take care *NOT* to loose the keys in the A and D shaft keyways - turn each shaft till the keyway is up before removing the gear. <br />
* The B and C gears are coupled by a hollow stub shaft (with an integral key), which is so tight in the gears it has to be pressed or driven out - I've made a puller just for this task, kept in the change gears tin.<br />
* The center of the B-C stub shaft *MUST* be lubricated where it runs on its pin on the change gear banjo bracket, with grease or heavy oil. ''Seizure of the stub shaft due to running dry is a frequent cause of catastrophic mini-lathe geartrain failures!''<br />
* Don't get oil on the change gears as it can cause plastic gears to crack. Only PTFE drylube or plastic compatible white grease should be used on their teeth. <br />
* Adjust the B-C pin position in the straight slot first to set the C to D gear mesh, tighten its nut, then swing the whole banjo about the D shaft boss to set the A to B mesh, and finally tighten the banjo clamping nut.<br />
* Check both gear meshes have running clearance by turning the chuck by hand enough to complete one full turn of the leadscrew, and by attempting to turn the intermediate gear(s) to assess backlash, If excessive resistance is felt or if there's significant backlash, readjust the gears. If you have difficulty judging the mesh, a strip of 80 gsm copier paper (approx. 0.1 mm thick) wound into the meshing teeth before tightening the stud or banjo will give appropriate clearance once removed. Once setup, check the gears run quietly under power.<br />
* If the sum of the tooth counts C+D is the same as for the ones you just removed and they were correctly meshed, you don't need to move the stub shaft pin. If A+B is <u>also</u> the same, you don't need to move the banjo. e.g. If it was set up for 16:1 reduction power feed, 1 mm (40:60 - 50:50) for M6 and 1.5 mm (e.g. 40:60:40) for M10 pitches can thus be achieved by only swapping gears. <br />
<br />
''The change gears, puller, etc. and a box spanner for the banjo nut are kept in a white rectangular tin behind the lathe.''<br />
<br />
=== Power Feed ===<br />
When used for turning with power feed, the change gears should be set for a 16:1 reduction (A:20 : B:80 - C:20 : D:80) using the pair of small metal 20 tooth pinions and the 80 tooth plastic gears (largest in set), for a feed of 0.09375 mm per turn (1.5 mm/16). Unless continuing your threading project the next session, please re-fit the 16:1 power feed set after threading so the power feed is ready for use. <br />
<br />
* *ALWAYS* leave the feed direction selector lever in its neutral (no feed) position, and the half-nuts open after use.<br />
* *ALWAYS* check the carriage lock is disengaged before engaging power feed. Unlock the carriage after use. <br />
<br />
=== Threading Dial ===<br />
The threading dial is an aid to re-engaging the half-nuts at the right moment so the tool will retrace its previous path cutting deeper, rather than offsetting axially some fraction of the thread pitch and ruining your work. Its based on the concept of the lowest integer multiples of the leadscrew and thread ''(being cut)'' pitches that exactly match, but for mechanical simplicity it only covers certain selected multiples of the leadscrew pitch.<br />
<br />
We have a choice of three pinion gears:<br />
{| class=wikitable<br />
|+ Threading dial Pinion Gears<br />
|-<br />
! Teeth !! Colour Dot !! Usable lines !! OD gear !! Dist. per turn<br />
|-<br />
| 14 || Red || 1,7 || 7.51 mm || 21 mm<br />
|-<br />
| 15 || Orange || 1,5,9 || 8.05 mm || 22.5 mm<br />
|-<br />
| 16 || Green || 1,4,7,10 || 8.37 mm || 24 mm (2 mm/div)<br />
|}<br />
They are now colour coded, with a paint dot on the gear end face ''(the only non-wear surface)''. The 16 tooth one is normally left on the lathe, but disengaged when not threading to minimise wear on the lead screw. The others are kept in the Change Gear tin.<br />
<br />
There's a threading dial 'pickup' calculator here: https://www.cgtk.co.uk/metalwork/calculators/threaddialindicator <br />
<br />
Initially select ''Lathe:'' '''Custom''', and enter the following below:<br />
* ''Units:'' '''Metric'''<br />
* ''Lead Screw Pitch (mm):'' '''1.5'''<br />
* ''Thread Dial Indicator Gear Teeth:'' '''16,15,14''' <br />
* ''Lines on Thread Dial Indicator:'' '''12''' <br />
* ''Line Marking:'' '''Every Line Numbered'''<br />
Note the teeth list is entered in reverse order so the resulting table highlights any required pinion changes.<br />
<br />
N.B. The dial is only friction clamped to the pinion by its center screw. If you have any reason to suspect it may not be properly aligned: <br />
# With the power off and the carriage unlocked, engage the feed direction lever upwards. You'll probably need to turn the chuck by hand to get it to engage.<br />
# If the threading indicator isn't already engaged, loosen the threading dial support block bolt, pivot the block to engage the pinion with the leadscrew and retighten the bolt.<br />
# Engage the half nuts, again turning the chuck by hand till they drop in. <br />
# Turn the chuck a couple of turns, top towards you to take up any backlash, then lock the carriage, taking care not to push it left while locking it.<br />
# Loosen the screw securing the dial to the pinion.<br />
# Align the '1' line of the dial with the index line, by rotating the dial clockwise, then retighten the screw.<br />
# Don't forget to disengage half-nuts and unlock the carriage!<br />
<br />
The above instructions should result in the half-nuts engaging cleanly when exactly on any valid line when threading towards the headstock. If it is required to thread away from the headstock, there will be a slight offset from the line due to backlash between the spindle gear and leadscrew, so engage slightly early.<br />
<br />
Changing the pinion:<br />
# Loosen the threading dial support block bolt and disengage from the leadscrew.<br />
# Undo dial center screw, and remove it and the dial, dropping the old pinion out the bottom.<br />
# Oil the shaft of the new pinion with a drop of light oil and insert it from below, gear end down.<br />
# Refit dial and screw.<br />
# Check the dial and pinion turn freely with minimal resistance.<br />
# Align as above.<br />
<br />
== Tailstock and Steadies ==<br />
These are mostly used to support long work ''(long with respect to its diameter)'' to improve rigidity, increasing accuracy and reducing chatter. The Tailstock quill is also used with a drill chuck for drilling.<br />
=== Tailstock ===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock base]]<br />
The tailstock can be offset to turn shallow tapers between centers. We don't currently have the accessories to turn between centers, namely <s>a MT3 dead center for the spindle, or</s> any drive dogs for the work. Also realigning the tailstock after turning a taper can be a PITA. The photo shows the tailstock adjusting screw locations ''(C - Lateral, and D - Skew)'' and the block on the baseplate they engage with. Adjustments can only take effect when the tailstock locking lever is eased to take the pressure off the baseplate. As we don't have a MT3 center, one has to turn a fresh point on a test workpiece for a rough tailstock alignment reference. Fine alignment, to avoid inadvertent taper turning, can be done by mounting a long precision ground bar between the chuck (or preferably a center in the spindle), and a dead center in the tailstock and sweeping it with a dial indicator on the carriage. Finally a test cut should be taken at either end of a bar between centers, and the diameters checked with a micrometer. Assuming the bed has previously been properly levelled and shimmed to take out twist ''(not the case at RML as we don't have it bolted down)'', any remaining difference in diameter will be double the tailstock offset, smaller at the tailstock being offset towards the front. Fine adjustment cant be achieved by jacking with the screws, its best to ease the adjusting screws, bump the tailstock into alignment then take up the screws again, checking the alignment is maintained when the tailstock is unlocked and relocked. There is no vertical adjustment, though shims can be added between the tailstock and its base.<br />
<br />
==== Tailstock Quill ====<br />
There is a metric/imperial scale on the top of the quill, read against the end of the tailstock, for depth measurement when drilling. The tailstock quill has a 1.25 mm pitch thread and a 50 division dial. Each division is therefore 0.025 mm, and it only takes 4 full turns of the handwheel to move the quill 5 mm. <br />
<br />
To eject MT2 taper tooling and centers from the tailstock, wind the quill all the way in.<br />
<br />
N.B. The quill anti-rotation pin (dog-tip setscrew + locking nut in top of tailstock near to the quill lock) is only M5. It will sheer if a large diameter drill jams in the work. Please back it out clear of its keyway if using large drills, and use alternative methods of preventing chuck rotation. To re-engage it, crank the quill out till you can see the keyway, align it with the screw and screw in the screw till it gently bottoms out, then back it off a quarter turn. Try twisting the quill to check its properly engaged, then tighten the locking nut gently to hold the screw in position clear of the bottom of the keyway.<br />
<br />
=== Steady Rests ===<br />
We have two, both with brass tips that must be kept lubricated during use.<br />
<br />
The fixed steady mounts on the ways, and is most useful when turning longer work that wont fit through the spindle bore. Adjustment is critical, and the surface the tips run on must be smooth and concentric, as any misalignment that forces the work off center will result in the work wobbling in the chuck, marring it, with a high risk of it becoming un-chucked, which can be dangerous at speed.<br />
<br />
The travelling steady mounts to the headstock side of the carriage to locally resist the deflection of thin long work, due to the cutting forces. It only has two tips, to resist climb, and deflection away from the tool, and requires readjustment after every cutting pass.<br />
<br />
== Tooling and Tool Holders ==<br />
'''Key dimensional data:'''<br />
* The quick change holders accept up to 10 mm shank tools. <br />
* The four way toolpost has 50 mm long sides, a seat width of 15 mm and can clamp tools of up to 5/8" (15.875 mm) shank ''(check this)'', but the slot base is only 10.4 mm below the spindle center so cannot be used with >10 mm shank tooling unless it has a dropped tip. Large tooling with a centered tip is also problematic as you run out of height above the shank when trying to shim to match the spindle center height. <br />
<br />
===Quick Change Toolpost===<br />
I've got the quick change toolpost and toolholders setup for mostly easy use. The three toolholders came with cantilever height setting arms which historically haven't been installed as the supplied fixing screws were too short. That's all now sorted out and a HSS RH turning tool and a HSS hand-ground grooving/parting-off tool are now mounted in two of the holders and set to height. The third is kept free for other tools. <br />
<br />
The quick change toolpost has been modified with a spring to press the dovetail clamp outwards and help stop it twisting or flopping about to ease toolholder fitting and removal. The dovetail clamp (socket headed screw on toolpost side opposite dovetail) feels a bit stiffer than before, but will take less than half a turn to go from open (with the toolholder lifting out or dropping in easily) to fully clamped. As there is so much less clearance in the open position you should no longer need to wiggle the toolholder while clamping it to get a consistent height. If the dovetail clamp ever gets misaligned, twist it straight by eye, slacken off a bit further than usual to get a toolholder on, clamp it to align the dovetail then release, reseat the toolholder and re-clamp to ensure its at its preset height. You cant adjust the height by 'jacking' with the height screw due to its offset leverage. Instead, back off the height screw and hold the toolholder at the desired height while locking the dovetail clamp, then adjust the height screw (and locking nut) to hold it there, then check it doesnt change height significantly when you unclamp and reclamp the dovetail. <br />
<br />
Unfortunately the OEM height setting screws foul the toolpost locking nut handle. Currently, if you need to swap toolposts you will have to first remove the quick-change tool holder from the post. There is enough nut handle swing to allow the quick change toolpost to be unclamped and rotated to fine set the tool angle without removing the toolholder. It also seems the mating surfaces may be slightly out of square, as if you rotate the toolpost 90° or 180°, the nut swing may be insufficient to re-clamp it without removing the toolholder to do so. Add a M10 washer under the locking nut if the handle ends up pointing in an undesirable direction! A thin M10 washer is kept with the toolpost collar for this purpose, and will shift the handle position by about a third of a turn. <br />
<br />
''ToDo: Make a taller nut of a similar pattern, to clear the height setting screws.''<br />
<br />
===Four Way Toolpost===<br />
The OEM four way toolpost is significantly more rigid than the quick change toolpost + holders because it has fewer and thicker parts and less overhang. Therefore the four way toolpost should be used when using carbide tooling. It requires shimming under the tool to set the tip height to the spindle center height - see below. The tool shanks are mostly significantly less than 15 mm wide, so need to be centered under its clamping screws, tempting as it is push the shank in for full side contact with the toolpost. If possible clamp the shank with all three screws not just two.<br />
<br />
==== Shimming ====<br />
We typically only mount up to two tools, and want maximum rigidity, so use 50 mm x 15 mm shims, (the full seat area), preferably with deburred edges and radiused corners so they aren't a hazard to the operator.<br />
<br />
We have pre-cut and marked shims of the following thicknesses: <br />
* 1x 3.23 mm, 2.42 mm, 1.56 mm, 0.32 mm, and 0.25 mm<br />
* 2x 1.00 mm, 0.77 mm, 0.12 mm, 0.11 mm, 0.10 mm and 0.05 mm<br />
* 4x 0.53 mm<br />
<br />
Our shims are mostly found materials (hence the awkward thicknesses) and are mostly a mixture of aluminium and steel, with a couple of GRP ones. The toolpost seat '''<u>must be absolutely clean</u>''' to avoid embedding debris in the aluminium or GRP shims, to get a consistent height and avoid tilting the tool - wipe it every time you change a tool! Put the thin shims at the bottom of the stack to avoid the tool shank edges creasing them. Shims are kept in a little yellow plastic box with a clear lid, near the carbide tools case.<br />
<br />
''ToDo:'' <br />
<br />
* ''Cut more shims neatly, mark them with their thickness.''<br />
* <s>''Do test cuts and start noting shim stack-ups for various tools.''</s><br />
* ''Organise shim storage!''<br />
* <s>''Possibly acquire, cut down and dismantle a feeler gauge set to get a better selection of marked steel shims.''</s><br />
* ''Make a tip height setting gauge''<br />
<br />
=== HSS Tools ===<br />
[[File:Tool Bit Geometry.jpeg|thumb|Single point cutting tool geometry]]<br />
Our HSS tools are made from 8 mm square bar stock, hand-ground to tip profile in-house. See LittleMachineShop's [https://littlemachineshop.com/images/gallery/instructions/grindingtoolbits.pdf Grinding Tool Bits] notes. <br />
<br />
I've installed our usual HSS LH turning and parting off tools in two of the quick change holders and set the heights correctly. There are a couple of other HSS tools or tool blanks knocking about. Taking heavy cuts turning steel (even with good cutting oil) blunts HSS tools fairly quickly, which are time-consuming to re-sharpen nicely without a dedicated tool & cutter grinder with appropriate jigs. Its worth noting that the usual 'speeds & feeds' tables are commonly based on surface speeds expected to give a half hour (active cutting) tool life before resharpening.<br />
<br />
I touched up the LH turning tool by lapping on wet & dry (silicon carbide) paper on glass (Aka: [https://en.wikipedia.org/wiki/Scary_sharp 'Scary Sharp']) working upwards through the grits 200, 400, 600 and finally 1000, initially 'bluing' the surfaces to be lapped with a marker pen to see which areas needed taking down more. The end of the tool was significantly uneven so I touched that up freehand on the bench grinder to flatten it when it became apparent that 200 grit lapping wasn't cutting where it needed to. There was an existing micro-bevel on the leading side, which I kept. Finally I 'dubbed' the leading corner vertical edge on the 1000 grit to give it a very slight nose radius. A test cut on brass gave a very nice finish when turning.<br />
<br />
''Ian B has purchased some spare 8mm HSS tool blanks - talk to a lathe trainer if your proposed lathe work needs custom ground HSS tooling.'''<br />
<br />
=== Brazed Tungsten Carbide Tools ===<br />
Somewhat of a half-way house between hand ground HSS tooling and insert tooling with the disadvantages of both and some more besides - e.g. they are much harder to sharpen. So why do we bother? Some tool geometries would be awkward and tedious to hand grind, and Chinese import brazed carbide tooling is about half the price of similar HSS tooling, and far more readily available. Also, for space constrained tooling like boring bars, if you want carbide, for insert tooling, the size of the insert and its clamping seriously limits the minimum hole diameter you can work in. I have purchased a set of 3/8" shank brazed carbide tipped boring bars, but we currently cant sharpen them, due to lack of a diamond grinding wheel. <br />
<br />
=== Tungsten Carbide Insert Tools===<br />
Decoding ISO insert tooling part numbers: https://www.cutwel.co.uk/blog/learn-the-turning-tool-iso-code-system<br />
[[File:Carbide set.jpg|800px|thumb|left|Our set of Tungsten carbide insert lathe tools (before the new inserts were fitted)]]<br />
<br />
{| class=wikitable<br />
|+ Tools, left to right, (+ last across top):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| SSKCR0610H06 || 75° through boring || SCMT06204 || Long || 6 || 6.34 || ''4.33''<br />
|-<br />
| SSSCR0610H06 || 45° deep facing, internal chamfering || SCMT06204 || Long || 6 || 6.13 || ''4.58''<br />
|-<br />
| SWUCR0610H05 || 93° boring, deep facing || WCMT050308 || Long || 6 || 6.22 || ''4.48''<br />
|-<br />
| SWGCR0810E05 || 90° RH turning & facing || WCMT050308 || Short || 8 || 8.25 || '''2.45'''<br />
|-<br />
| SSSCR0610E06 || 45° turning, chamfering || SCMT06204 || Short || 8 || 8.75 || ''1.93''<br />
|-<br />
| SSBCR0610E06 || 75° RH turning, chamfering || SCMT06204 || Short || 8 || 8.72 || ''1.98''<br />
|-<br />
| LW0810R-04 || 60° external threading || JCL15-120 || Short || 8 || 7.44 * || ''3.28''<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || 8.23 || ''2.5 ?''<br />
|-<br />
| LN0813R-04 || 60° internal threading || JCL15-120 || Long || 7.95 || 7.44 * || ''3.28''<br />
|}<br />
<br />
{| class=wikitable<br />
|+ More Tools, (loose in tin):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || ~8.5 (not in use) ||<br />
|-<br />
| [https://www.glanze.co.uk/product/glanze-12-mm-60-degree-metric-internal-threading-tool/ Glanse SIR0012K11] || 60° internal threading bar || 11IRA60 || Long || 12 dia || ??? || ???<br />
|}<br />
''Shim stack heights in bold are tested, in italic are only calculated.'' ''Tip heights marked * are with new JCL15-120I inserts. The single remaining plain JCL15-120 insert has a slightly higher tip height.''<br />
<br />
Carbide tooling typically requires two to three times more speed than HSS and at least a couple of 'thou' depth of cut for best results.<br />
<br />
Chatter can rapidly kill carbide tooling by chipping the cutting edge. To improve rigidity and reduce the risk of chatter, the cross-slide and compound gib screws need to be well adjusted so there is minimal play in the slides, tool stick-out should be minimised, the four way toolpost should be kept over the cross-slide, and the work should be kept close to the chuck (or otherwise supported by tailstock or steady rest) to avoid excessive deflection.<br />
<br />
Thermal shock is almost instant death to carbide, and when dry cutting the insert tip can run very hot, so do not add extra cutting fluid manually during the cut. Pre-apply what you need, evenly, before starting the cut.<br />
<br />
Parting off or facing to center is high risk - if the tool tip is even slightly below center or if tool or work deflection takes it below center, the work will tend to climb over the tool tip as the cut approaches center, breaking the insert. To avoid this, the tool should be shimmed slightly above center, sufficient to allow for work and tool deflection, and unless very close to the chuck, a steady should be used. Its often preferable to part to a couple of mm dia. remaining then stop and saw through the remainder. Parting off hollow parts is much lower risk.<br />
<br />
Further investigation of the Tungsten carbide insert tool height situation is not encouraging - the so-called 'set' in question does not have a consistent tip height ''(see above table)''! In a real set, the insert seats *should* be machined allowing for the insert thickness to bring all the cutting edges to the same height with respect to the shank underside. However if you place them tip to tip on a table its easy to see there is considerable height variation, so they need to be individually shimmed (or at best, one machined shim will only be right for two or three tools). At this time we don't have dedicated shim stacks for each tool.<br />
<br />
A 2.42 mm thick shim brings the SWGCR0810E05 90° RH turning & facing tool almost exactly to center height, and good results were obtained turning 1" steel pipe. However facing 50mm steel bar stock to center found it to be slightly low, leaving a fractionally under 0.05 mm 'pip' so it needs another 0.03 mm to bring it fractionally above center. Fractionally too high is generally preferable to fractionally too low, due to tool deflection, so adding an 0.05 mm shim to the stack should produce optimum results.<br />
<br />
==== Inserts ====<br />
Ian B has purchased the spare inserts we needed in sets of five. He even was able to get the CK3 parting-off inserts which had been difficult to source!<br />
<br />
Inserts used in above tool set:<br />
* 3x SCMT06204 (square, indexable) https://www.rdgtools.co.uk/acatalog/SCMT-06-Carbide-Insert.html<br />
* 2x WCMT050308 (triangular, indexable) https://www.rdgtools.co.uk/acatalog/WCMT-05-T3-08-5XTIP-8813.html<br />
* 2x JCL15-120 (60 deg threading point) https://www.rdgtools.co.uk/acatalog/X5-JCL-15-120L-THREADING-TIPS-60-DEGREE--X5-TIP---23455.html<br />
* CK3 (parting off) https://www.rdgtools.co.uk/acatalog/CK3-CARBIDE-TIPS---PARTING--BOX-OF-5PCS--9437.html<br />
<br />
Inserts used in other tools:<br />
* 1x CK3 (as above) also missing from spare parting off tool<br />
* 1x 11IRA60 in Glanse threading bar + 1x spare<br />
<br />
=== Drills ===<br />
Various sizes of center drills are kept in a plastic bag next to the wooden accessories tray. There's also a small box of 2.5 mm center drills.<br />
<br />
We have a set of 11 TiN coated HSS drill bits from 1.5 to 8 mm, (in a cylindrical plastic index box) for tailstock drilling of brass, aluminium and non-abrasive plastics. To keep them sharp enough for the precision work we expect from the lathe, please don't use them for steel or reinforced plastics, and don't borrow them for non-lathe use. Metric and US [https://littlemachineshop.com/reference/numberdrillsize.php numbered]/[https://littlemachineshop.com/reference/letterdrillsize.php lettered] general use HSS drill bits are kept in two red metal index boxes next to the drill press.<br />
<br />
== Using the Lathe ==<br />
=== General ===<br />
A cutting speed chart for HSS tooling, published by Model Engineer magazine can be found [https://www.model-engineer.co.uk/sites/7/documents/cutting%20speed%20chart.pdf [here<nowiki>]</nowiki>]. The second row is the target feed rate and the rest of the chart, apart from the diameter column is RPM.<br />
<br />
For carbide tooling cutting iron and steels, recommended speeds are generally three times higher than for HSS, but the CJ18A 2500 RPM max. spindle speed (in high gear) means you can only reach the optimum speed range for over 15 mm dia work. For small diameter work, HSS tooling may well be a better choice.<br />
<br />
An online metric speeds calculator is here: https://www.cgtk.co.uk/metalwork/calculators/cuttingspeeds <br />
<br />
How to do the maths to calculate speeds and feeds: https://www.cutwel.co.uk/blog/speeds-feeds-made-easy<br />
<br />
Making dimensioned parts is primarily done by touching off the tool tip on a reference surface (with the lathe stopped, turning the chuck by hand), zeroing the handwheel dial, then manually counting turns and divisions. When backing off the tool its best to do so by exactly one whole turn so you don't forget the previous dial position. Stopping and measuring the work before taking the final cuts is essential if high accuracy is required. ''I've changed out the dial setscrews for flat tip ones with a tiny slug of solder under them so the dials are now friction fit on their shafts. i.e. if you hold the handle firmly taking up the backlash in the direction of cut, you can zero the dial just by grabbing and twisting it.''<br />
<br />
Carriage movement is less easy to measure as the handwheel is uncalibrated and advances an awkward bit over 19.2 mm per turn. Your options here when shoulders or other features must be exactly positioned are, in order of increasing accuracy: <br />
* Use measuring instruments, scribe the work at the desired length then work to the scribed line. Its often convenient to black the work with a permanent marker, then scribe with the tool tip, turning the chuck by hand.<br />
* for short distances, lock the carriage and use the compound, set parallel to the work<br />
* Set up a long travel dial indicator to measure carriage motion. <br />
N.B. with the leadscrew stopped, and the threading dial engaged, with its default 16 tooth gear, it will make one turn for every 24 mm of carriage movement (2 mm/div). This isn't accurate enough for positioning but is sufficient to check you aren't out by a whole mm or more.<br />
<br />
Do not allow any solvents to contact the chuck guard clear plastic as it will make the plastic brittle, or even craze it, and try to avoid melting it with the work light!<br />
<br />
=== Slide Locks ===<br />
* The carriage can be locked to the ways using the M5 hex screw through the top of the saddle to the left of the cross-slide. Double check the leadscrew is disengaged and the half-nuts open before locking it. Lock it when facing.<br />
* The cross slide is drilled and tapped for a M4 locking screw, just in front of its middle gib screw, but currently no screw is fitted. Locking the cross slide is helpful when turning very shallow conical features where the cross slide handle is in the way of the compound.<br />
* The compound slide can be locked by a M4 socket headed cap screw in line with the edge of the toolpost mount on the side with the gib adjustment screws. In normal use it should be kept backed off half a turn but it is desirable to tighten it for parting off operations to keep the resulting end faces flat.<br />
<br />
=== Chucks and Chuck Jaws ===<br />
==== Terminology ====<br />
* Inside jaws have steps on the outside to grip the ID of hollow work, but can also be used as outside jaws on small diameter parts (i.e. that fit through the spindle). <br />
* Outside jaws have steps on the inside to grip the OD of the work.<br />
* Universal chucks have a scroll plate with a spiral screw thread that moves all the jaws.<br />
* Independent chucks have individual adjusting screws for each jaw.<br />
<br />
==== The Chucks ====<br />
* The three jaw universal chuck can only grip near round or hexagonal work, which it centers, but its concentricity is not perfect so e.g. if you reverse the work and continue turning at the same diameter from the other end, you will see a line where the turned surfaces meet. It has separate sets of inside and outside jaws, and we normally keep the inside set installed to use as outside jaws for small diameter work.<br />
<br />
** Our jaws are individually numbered, stamped in the groove. They must be fitted in the correct sequence. The jaw slots are not clearly marked. Lowest runout for small dia. parts is achieved if you fit the jaws with #1 anticlockwise of the makers mark, then continue anticlockwise for #2 and #3.<br />
** A large strong rubber band is a great help getting all the jaws started on the scroll together - with slots #1 and #3 above the centerline and the scroll thread outer tip between #1 and #3, insert jaws #1 and #2 and put the rubber band round them to keep them in their slots. Insert jaw #3 and stretch the rubber band over it to hold it up into its slot. If the scroll was positioned correctly, all jaws should be at the same initial radius. The jaws can now be cranked in with the chuck key and they should all engage in step so they meet in the middle.<br />
:: ''Mini-lathe.com have the best instructions for [https://www.mini-lathe.com/mini_lathe/chucks/chucks.htm#Installing_Chuck_Jaws changing the jaws].'' <br />
<br />
* The four independent jaw chuck can grip most roundish or squarish work, which can either be carefully centered by the user, or deliberately gripped off-center. <br />
** Its jaws are reversible so can be swapped from inside to outside by simply cranking each jaw out and reinserting it the other way round, one at a time. DON'T move the jaws to different slots as they are likely to bind.<br />
** When setting up to face the sides of rectangular objects held crossways, it may be helpful to use both inside and outside jaw orientations, in symmetrical opposing pairs.<br />
** Its screws move their jaw 1/8" (3.125 mm) per turn<br />
<br />
* The jaws must '''never''' protrude from the chuck OD by more than one step, and for safety, its preferable they don't protrude at all, as they make the gap between the front of the bed and the chuck body an even more unforgiving meat grinder, and as the number of teeth engaged with the scroll or screw decreases, they loose strength, just when you need it the most to grip larger/heavier work. <br />
<br />
''Neither chuck is well suited to gripping tapered work safely. When seating work that doesn't quite fit through the chuck bore (which is larger than the 20mm spindle bore limit), be careful that it isn't seating on the chamfered edge of the chuck bore as it is far to easy to get the work slightly cocked so it doesn't run true.''<br />
<br />
==== Changing Chucks ====<br />
* When changing chucks, use the small grey plastic mat to protect the ways under the jaws in case you drop the chuck.<br />
* The spindle nose has two patterns of holes - the three hole pattern is for the three jaw chuck and the faceplate, and the four hole pattern is for the four jaw chuck. One hole is shared between the patterns, and is marked on the spindle nose.<br />
* To fit a chuck:<br />
** First check that the spindle nose and chuck back and recess are free of swarf, grit or other debris. Any foreign objects will tilt the chuck causing excessive runout and may mar the surfaces.<br />
** Remove the nuts and split lock washers from its studs, line its studs up with the hole pattern (preferably with the stud nearest anticlockwise to the makers mark through the marked spindle hole), fit and hold it in place with your right hand, and with your left, get the lock washer and nut on the top stud, and take up the slack.<br />
** One one nut is on, you no longer have to worry about dropping it, and can work round fitting the remaining washers and nuts, taking up the slack on each as you fit it. <br />
** Next, work round again getting them all finger tight, then tighten them gently, and finally work round fully tightening them. <br />
* Removal is the reverse of refitting. Put the washers and nuts back on the chuck's studs so they don't get lost.<br />
<br />
=== Faceplate Work ===<br />
Faceplate work is probably the most dangerous operation you can (or rather should) perform on a lathe. The working area is a large diameter spinning surface with protruding clamps to fixture the part that it is impractical to guard. Protruding clamps, studs, nuts etc. are very difficult to see at speed.<br />
<br />
'''Treat the faceplate with great respect and caution if you wish to continue to be able to count to ten on your fingers!''' <br />
<br />
The 65 mm cross-slide travel vs the 80 mm faceplate radius is a serious limitation that may require creative compound, toolpost and tool setups for larger parts, and doing full face cuts in two sections.<br />
<br />
''It is common practice to skim the faceplate to ensure it runs true. We have not (yet) done this, and wont till the spindle is in better bearings and the nose reground to minimise runout.''<br />
<br />
==== Clamping ====<br />
Open ended/sided clamps should be oriented so that cutting forces drive the work towards the clamping bolt/stud, not out from under the clamp. Minimize the protruding length of thread past the clamping nut, if necessary using sacrificial bolts or studs you can cut to length, or even using a long M8 stud for one of the faceplate mountings, so you can get a clamp nearer to the faceplate center. Double-check all clamps are secure, manually turn the faceplate to check the work and clamps clear the ways, top-slide and toolpost, and stand out of the 'line of fire' (a disc extending from the faceplate) when spinning up the work for the first time. <br />
<br />
If you need to machine close to a clamp, consider marking a safe limit circle on the faceplate and work with a marker pen to make it easier to see how close the cutting tool is to crash disaster. <br />
<br />
I strongly advise reading chapter two of Tubal Cain's book "Workholding in the Lathe" several times before your first faceplate setup, and if possible get another experienced lathe user to check your first few setups before spinning them up.<br />
<br />
==== Chuck Guard Removal ====<br />
The faceplate is too large diameter to fit under the chuck guard, but the guard has an interlock switch wqhich must be closed for the lathe to run. The guard is now fitted with wing nuts so it can be removed allowing the the interlock switch to close when using the faceplate. It *SHOULD* *ALWAYS* be refitted if a chuck is fitted, except when turning work too large to clear the guard. <br />
<br />
''The chuck guard is primarily there to make it very difficult to start the lathe without removing the chuck key and to reduce the area of large diameter spinning surface exposed. It may slow down the projectile if a chuck sheds a jaw but is unlikely to stop it. Also it serves to contain coolant spray spun off the chuck. As we don't use flood coolant this usually isn't an issue for us. As setting up for faceplate work doesn't use a chuck key, and the most hazardous zone is the face of the faceplate, with its spinning projecting clamps, with full access required for machining operations, which a guard would not cover, the consensus is that removing the guard is an acceptable risk.''<br />
<br />
=== Turning and Facing ===<br />
We are getting good results in aluminium, brass, and even steel using HSS cutting tools in quick-change tool holders, and the ~ 94 um/turn power feed. Unfortunately due to lack of rigidity in both the machine and smaller diameter parts, if you don't want the outer end to be over diameter, a light final cut and multiple 'spring' passes will probably be required.<br />
<br />
For aluminium, a sharp HSS tool and 0.5 mm (20 div) depth of cut gives good results with power feed for rapid stock removal. Its also easy maths as each cut takes ~ 1 mm off the diameter. Finish cuts should be much finer, 0.1 mm (4 div) is 'in the ballpark'.<br />
<br />
For steel, using carbide insert tooling, a 0.25 mm (10 div) depth of cut is more appropriate, and with pre-applied cutting oil, gives reasonable results with power feed if you use enough speed. The maths is not quite so easy as you are only taking 0.5 mm off the diameter per pass. Again, use finer finish cuts but try to plan your cuts so the final cut is still cutting, not smearing the surface!<br />
<br />
When facing or parting off, some skill is required to turn the cross-slide handwheel steadily to get a decent finish and to avoid shock-loading the tool tip. Increasing the spindle speed in one or more steps to keep up with the reducing diameter is advisable, but avoid speeds that cause resonances (resulting in chatter). When parting off, small through-hole parts may be caught on a thin rod chucked in the tailstock, and pre-positioned inside the work with its tip right up to the parting off position.<br />
<br />
==== Using the Steady Rests ====<br />
For the fixed steady rest, see Blondihacks' Lathe Skills #26 - How To Use a Steady Rest! [[#Youtube_Playlists_&_Videos|{below}]]<br />
<br />
Ours doesn't have ball bearing fingers, so a smooth surface on the work and adequate lubrication are essential. The thumbscrews can only tighten the fingers, so for small adjustments outwards you need to either slack off the clamping nuts or ease them slightly and use a drift against the back of the finger's slot. Once set, check the chuck still turns freely.<br />
<br />
The traveling steady rest needs to run on a machined surface, so at least for the first pass, must follow the tool, so its difficult to avoid using more compound slide overhang than is desirable. An initial surface should be cut next to the chuck or tailstock center before fitting the steady rest.<br />
<br />
Both are a PITA to fit - the fixed one has to have its clamping post inserted up through the bed, and the supplied spanner is useless near the headstock, and the travelling one's mounting holes on the saddle almost invariably need swarf picked out of them.<br />
<br />
==== Turning Between Centers ====<br />
<s>Using a MT3 to MT2 reducing sleeve, the MT2 dead center can be fitted in the spindle.</s> ''Currently the MT3 spindle taper is compromised.'' Alternatively, a soft center can be turned immediately before use in the three jaw chuck, but that must have its 60° point re-cut to concentric if the chuck is disturbed, and needs to be either large enough to bear on the chuck body, or must have a lip to bear on the end face of the jaws to take the axial thrust. Recutting the center is a PITA, as the compound angle must be set to 30° anticlockwise, then reset to a true 0° afterwards. Maybe a right-hand 30° end angle zero rake form tool is the answer, or use the carbide insert tool SSKCR0610H06 as a form tool with the toolpost rotated 15° anticlockwise.<br />
<br />
With the MT2 live center in the tailstock quill, this gives us a center either end of the work to hold it.<br />
<br />
We also need a drive dog similar to [https://littlemachineshop.com/products/product_view.php?ProductID=4473&category=1 this], and the corresponding drive post to bolt to the spindle nose. I have some 25mm bore thick wall iron pipe, which should do nicely. Lengths of the dog's straight tail and of the post TBD after I check how much the center protrudes. N.B. its recommended to tie the tail to the post to keep them in contact so they don't slam. ''Currently we will need to drive from the chuck jaws. Possibly use the exterior jaws with a short soft center gripped on the inside end and drive from the highest step.''<br />
<br />
=== Drilling ===<br />
Always start with a center drill so deflection of longer bits doesn't start the hole off-center. For larger bits (> 5 mm), first drill to the web size, then to final diameter. For a precision hole, drill slightly undersize and ream to final diameter. ''Supply your own reamers!''<br />
<br />
Caution: See note about the quill anti-rotation pin in section [[#Tailstock Quill|Tailstock Quill]] above.<br />
<br />
=== Boring ===<br />
Caution: As the spindle doesn't extend right through the headstock housing, if boring in a through hole, chips tend to fall out the back and tumble in the spindle bore till they fall into the change gears. To avoid this, one should plug the spindle bore with a wad of paper towel or rag and when cleaning up afterwards, use a rod to push it through towards the tailstock, with the chuck jaws (if fitted) wound clear of the spindle bore.<br />
<br />
A swivel bladed hole deburring tool (pale blue handle) can be found in the main room on the windowsill behind the drill press.<br />
<br />
A couple of boring jobs have been bodged with an awkwardly angled turning tool and achieving acceptable effective rake with enough clearance to reach deep enough into the hole has been problematic. I reviewed the tools we had and found none suitable for starting out in a 13mm bore, the max diameter we can (easily) drill. I therefore decided to buy a set of boring bars and make a holder for them. I had difficulty finding anything affordable under 10mm shank - the best low cost option was a [https://www.amazon.co.uk/dp/B07P5LGVBX set of nine 3/8" (9.525 mm) shank brazed carbide tipped boring bars], which would be close to the max capacity of the quick change boring bar holder - if we had one! Unfortunately this holder for our specific toolpost is difficult to find except in a toolpost bundle. Another annoyance is the variable tip height of the set, varying from 1.8 mm to 2.8 mm above the center of the shank.<br />
<br />
I therefore decided to make a boring bar holder of the [https://littlemachineshop.com/products/product_view.php?ProductID=1700 Littlemachineshop.com (USA) style] for use in the four way toolpost, as the additional rigidity will certainly help. Starting with a slightly over 50 mm length of 16 mm aluminium square bar and using the four jaw chuck , both ends were faced and an attempt was made to find its center and center drill it. It was then drilled out to ~9.8 mm after much drama due to blunt drills and drills that cut ~1mm oversize. Too big, but beggars cant be choosers as we didn't have a boring bar holder or a 3/8" reamer. Unfortunately the final hole ended up significantly off center. It was then chucked crossways and ~1 mm skimmed off its thickest side to gain clearance to allow it to be shimmed to height, then one side was slit lengthwise manually with a hacksaw.<br />
<br />
It was fitted to the for way toolpost and loaded with a booring bar, which clamped firmly. A 0.86 mm shim stack brought the tip of the largest boring bar almost spot on center height, with the difference easily accommodated by twisting the tool slightly. The three jaw chuck was then remounted, and a piece of iron pipe chucked for a test. It cuts well and leaves a decent surface finish.<br />
<br />
''The boring bar setup is a work in progress - talk to me before attempting to use them if you have a project that would benefit from boring..''<br />
<br />
ToDo: get something that can sharpen tools tipped with this grade of carbide - it needs some sort of diamond (or possibly CBN) wheel as green grit silicon carbide does little more than polish it. ''N.B. diamond wheels are rapidly eroded by grinding steel, so the supporting steel seat must be undercut with a regular grinding wheel before the diamond wheel can contact it.'' <br />
<br />
We'll also need 50 mm square sheet shims to fit under the toolpost to gain clearance in the toolpost above the tool or toolholder. A 2.4 mm shim would give us about the same above and below spindle center height, and we probably need a small selection of thinner ones.<br />
<br />
=== Thread Cutting ===<br />
The objective is to cut a thread that complies with the ISO metric thread profile. Our lathe is not currently equipped to cut non-metric threads, (with the exception of BA which have pitches based on metric threads of that era).<br />
<br />
[[File:ISO and UTS Thread Dimensions.svg|frame|center|Metric Thread Profile - from the geometry, H is ~86.6% of P]]<br />
<br />
Metric thread data - See 'Preferred Sizes' at: https://en.wikipedia.org/wiki/ISO_metric_screw_thread<br />
<br />
See "Mini Lathe User’s Guide" section '''Threading''' for general techniques *ONLY*, and above for change gears and threading dial setup.<br />
<br />
Amadeal specify the max. thread pitch as 2.5 mm. Any thread pitch greater than 1.5 nn requires the change gears to gear up. When gearing up it is desirable to distribute the ratio as evenly as possible over the two pairs of gears in the geartrain to avoid excessive tooth loading.<br />
<br />
==== External Threading ====<br />
Initially turn work to required Major Diameter, set up change gears and threading tool, touch off on the work, zero the top and cross slide dials, and do a 'scratch' pass to check the pitch. Back off the tool, return the carriage, and re-engage the half nuts on a valid dial line clear of the end of the thread then immediately stop the lathe, and hand turn the chuck till the tool tip is (hopefully) over the scratch to check the thread pickup. If all is good, return the carriage again, restart the lathe and start cutting your thread. <br />
<br />
Methods of doing so vary depending on the size of the thread and toughness of the metal, but straight-in plunge cutting is generally to be avoided as has the highest cutting forces, and does not reliably keep the carriage (and top-slide if set parallel to the work) loaded to avoid pitch errors due to backlash. <br />
<br />
If leaving the half-nuts engaged and reversing the lathe to return to the start of the thread for the next pass, its absolutely essential to back the tool out of the thread for the return pass as it will not follow the path of the cutting pass due to backlash in the geartrain, leadscrew mounts and half-nuts.<br />
<br />
==== Internal Threading ====<br />
''<nothing here yet>''<br />
<br />
== Cutting fluids ==<br />
=== Why bother? ===<br />
[https://youtu.be/mRuSYQ5Npek Watch this video] and contemplate what's actually happening to that thin ribbon of metal being removed. Most of the lathe's motor power is being turned into heat by internal friction in the chip being removed in the zone around the cutting edge, and surface friction at, and immediately behind the cutting edge, near-instantly heating the chip by up to several hundred degrees. Reducing the surface friction using a suitable cutting oil reduces the strain on the machine as a whole, and reduces workpiece and tool heating (and thus expansion) with consequent improvements in maximum usable feed and depth of cut, surface finish and accuracy. It also drastically increases the life of the cutting edge.<br />
<br />
=== Practicalities === <br />
We don't have a coolant system for the lathe and *really* don't want the maintenance hassles of using soluble cutting oil/coolant as if used infrequently its a PITA to keep recirculated high water content cutting fluids from going rancid and stinky, and they can also rust the ways, so even a total loss gravity feed system is problematic. Therefore if dry machining doesn't give a good enough finish, we tend to use oil applied topically, by hand to the work. <br />
<br />
* Hard brass is typically free-turning without oil, however some light oil for the final cut can improve surface finish, but with the disadvantage that it will increase loose chip buildup on the tool as hard brass typically forms short spalls or splinters rather than curly chips.<br />
<br />
* Many Aluminium alloys tend to be gummy, and Paraffin or other mineral spirits mixed with a little oil can help prevent the aluminum welding to the tool edge. WD40 will do at a pinch, but its messy to apply from a spray can.<br />
<br />
* Steel really needs *GOOD* cutting oil. Lard oil is the traditional choice for steel. If there are any objections to lard oil, we should bite the bullet and get some commercial dark high Sulphur cutting oil, but beware, many such oils use an additive package that includes lard oil.<br />
* Cast iron (except ductile) should be cut dry, as the carbon micro-inclusions self-lubricate it, and the carbide in the dust (primarily Cementite) are very abrasive, so tend to form a grinding compound if mixed with oil. <br />
<br />
I've sorted out an oil pot lid with a 1/2" brass collar soldered in to give a nice smooth sided hole, for ease of use and to minimize the risk of spills when using a brush to apply cutting oils, and got some dirt-cheap brushes. It fits Shippam's paste (and similar own-brand spread) jars and I've found several jars and ordinary lids to seal them for storage. Unfortunately it isn't the easiest to get this type of jars' lids back on square so they seal properly, and if you over-tighten them and there's a temperature change, they can be a total <expletive> to reopen. Using the rubberised handles of a large pair of pliers to grip the jar lid just above its rim is the best option, and avoids damaging the lids.<br />
<br />
''N.B. For the smaller brushes, the glue holding the bristles in is attacked by paraffin. To prevent loss of bristles, crimp the aluminium ferrule of each new brush of this type before use.''<br />
<br />
We have, in labelled jars:<br />
<br />
* Sulphurised Lard oil thinned with paraffin. Best choice for heavy cuts and threading in steel but stinky.<br />
* Lard oil thinned with paraffin. Good for steel and acceptable for softer copper alloys<br />
* Paraffin with a trace of light oil. Good for aluminium, and can help prevent squealing chatter on finish cuts in brass.<br />
<br />
I've also got some paraffin wax (in the form of a stubby candle), which can be applied lightly (under power) to brass and aluminium stock especially on the finish pass. It makes less mess than oil but unfortunately tends to build up on the tool tip, making it difficult to 'work by eye' without frequent pauses to clean the tool tip.<br />
<br />
We've also got a tin of [https://www.rocol.com/products/rtd-compound Rocol RTD cutting compound], which is a thick paste. Its highly recommended for drilling and tapping steel (in the drill press or by hand), but as a paste, is less useful for general lathe work unless thinned to a fluid consistency, e.g. with paraffin or white spirits. OTOH its certainly worth trying for high speed facing steel as it is less likely to get flung off.<br />
<br />
== Cleaning and Maintenance ==<br />
Swarf is a significant cut hazard to the operator, especially stringy swarf from cutting steel. Never touch it bare-handed - always use a tool e.g. a brush, or a hook, or needle nose pliers for grabbing long swarf.<br />
<br />
* After use, brush all swarf off the toolholder, compound and cross slide etc. ways and leadscrew. Ian B has blocked off the opening at the headstock end of the rear splashguard (to try to keep swarf out of the motor), so one must sweep the swarf towards the open tailstock end and catch it in a dustpan or similar. Preferably, also thoroughly clean out the chip tray under the lathe, but at least sweep out visible swarf.<br />
* Wipe up any cutting fluid residue and re-lubricate affected sliding surfaces with way oil.<br />
* Do not solvent clean the chuck guard, as it will make the plastic brittle, or even craze it. Water with a little detergent is permissible for cleaning it, with the guard totally removed from the lathe.<br />
<br />
Before engaging the half-nuts for power feed/threading, check the leadscrew is clean! ''Best cleaned under power, with a toothbrush.'' <br />
<br />
'''Caution:''' The traverse gears behind the carriage handwheel are in an open-backed housing and tend to become packed with swarf! Swarf buildup here will result in jerky carriage movement. Clean out as much as you can with a toothbrush ...<br />
<br />
===Lack of lubrication and/or swarf or dirt build-up can be disastrous===<br />
* If using the change gears/power feed, lack of lubrication of the B-C stub shaft center pin or either leadscrew end bearing can result in seizure and immediate destruction of one or more gears in the gear train or worse. <br />
* Small pieces of swarf can get between the saddle and ways, or into the slides degrading accuracy, possibly permanently if hard swarf scores them, or jamming them. The carriage handwheel gears behind the apron are notorious for accumulating swarf, and swarf buildup on the leadscrew can prevent the half-nuts engaging properly, resulting in scrapped work, and possibly stripped half-nuts. <br />
* Metal swarf can get into the motor (''though Ian B has modified the rear chip catcher to reduce the risk)'' or into the control box via the leadscrew, and short-circuit stuff. At best it will blow the fuse and need a strip-down to clean it out, at worst it may require a replacement [https://www.amadeal.co.uk/acatalog/Speed-Control-Circuit-Board--12amp-AMA_SP_CJ18_SCB12.html#SID=12 speed controller] ''(currently £96)'' and/or [https://www.amadeal.co.uk/acatalog/550W-motor-for-CJ18A-Mini-Lathe-467.html#SID=240 motor] ''(currently £105)'' and possibly other electrical parts. We should probably fit a [https://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C3-Mini-Lathe-Spares/C3-256-Leadscrew-Grommet-Dustproof-Cover C3-256 Leadscrew Grommet] to keep swarf out of the control box, as it tends to drop onto the 'Filter' board which is mounted horizontally, below the leadscrew.<br />
* Grit from grinding, sanding etc. forms a grinding paste with the way oil, and will rapidly wear out the ways, saddle and slides. Keep grit off at all costs e.g. by covering the ways and slides during grinding/sanding operations, and if there's any chance grit has gotten where it shouldn't, clean and re-lubricate *BEFORE* moving the carriage or slides, then move the carriage and slides, wipe down where they were with a clean paper towel and check there's no remaining traces of dirt other than clean way oil on the paper towel. If it doesn't come clean when you re-lubricate and move it again, a full strip down may be required to solvent clean and relubricate the precision sliding surfaces.<br />
* Although a metalworking lathe *can* be used to turn hardwood, wood dust and small chips are extremely pernicious, as they get everywhere, even clinging to clean surfaces, are abrasive due to their silica content, and are hygroscopic, promoting rust. An even more thorough clean-up than after using abrasives is needed, immediately afterwards. Oily wood dust and fine wood chips in significant quantities are a fire hazard, even in the trash bin.<br />
<br />
===Lubrication===<br />
See section: "Lubrication" in LittleMachineShop.com "Mini Lathe User’s Guide" [[Ian_M's_Lathe_Notes#Manuals|(below)]]. As we usually only open two nights a week, in the table on page 16, Daily lubrication becomes Weekly and Weekly becomes Monthly.<br />
<br />
===General Maintenance===<br />
* The grubscrews holding the cross-slide and compound slide dials tend to loosen due to vibration and use of the dials. Keep them snugged up, but not so tight the dials cant be set without an Allen key.<br />
<br />
* The screws holding the cross-slide nut tend to work loose due to vibration. Crank the handle to and fro through the backlash and visually check there is no movement of the screw heads in their holes. If there is, see the [[#Excessive_cross-slide_backlash|notes below]].<br />
<br />
===Removing the Carriage===<br />
Its possible to remove the carriage from the bed for cleaning etc. without dismantling it. The only stop to its motion is the righthand leadscrew bearing.<br />
<br />
Start by removing the tailstock. Crank the carriage to the tailstock end then remove the leadscrew bearing (two screws and a nyloc nut on the leadscrew end). With the half-nuts open, hold the leadscrew centered in them and crank the carriage off the end of its rack, then slide it off the end of the bed.<br />
<br />
Refitting is the reverse of removal, except (if its gibs are correctly adjusted) the carriage will be very tight on the end of the bed ways so may be difficult to work onto the ways without a stack of blocks of wood or similar to support it at exactly the right height. The righthand leadscrew bearing must be refitted with the carriage as close as possible to it and the half-nuts firmly closed to support the leadscrew at the correct height to hold it in alignment while the screws are being tightened. The nyloc nut controls leadscrew end-play. Fully tighten it then back it off slightly till the leadscrew turns freely with its change gear removed.<br />
<br />
If the Apron has been off, refit it with the screws no more than lightly finger tight and only finally tighten them after checking lead screw engagement at both ends of the carriage travel and that the rack and pinion operates smoothly over the full travel.<br />
<br />
== Issues and Annoyances ==<br />
As of September 2023 - mostly resolved, apart from the spindle bearings and runout, the lathe is in better condition than it has been for a number of years.<br />
<br />
===Four Jaw Chuck has two jaws too tight===<br />
Fixed 27/10/2023: The grooves in the opposite sides of the jaws that run in the chuck slots were slightly out of true, and the rails either side of the slots were slightly too thick towards the center. Due to the difficulty of seeing the high spots, after cleaning up and deburring the jaws didn't do enough to ease them, I decided to grind the top of the rails where they were binding. Several repetitions of spotting, grinding then diamond filing the high spots has eased them enough. I cleaned everything, greased the jaw slides and screws, and refitted the studs so the chuck is now fit for service. <s>Two of the chuck jaws are tight in their slots, making precise adjustment difficult due to lack of 'feel'. Moving the jaws round the slots shows the problem follows the jaw not the slot, and stoning various edges hasn't helped so it seems that the affected jaws are slightly oversize. Need Engineer's spotting blue to determine which of the sliding surfaces is binding, so we can see what needs scraping/stoning/grinding to fix them</s><br />
<br />
''N.B. Don't move the jaws to a different slot - the formerly tight jaws *must* stay in the slots furthest from the makers mark.''<br />
<br />
===Excessive Runout===<br />
Mostly fixed 24/10/2022: I ground the chuck seating surface of the spindle nose (outside lip) to under half a thou runout. This also cleaned up several burrs. It would be possible to do better, but that would need good spindle bearings, and a more rigid toolpost grinder mount.<br />
<br />
Our spindle nose was damaged years ago by a person with little mechanical aptitude (who shall remain nameless) beating it up with a hammer mushrooming the spindle nose. We are getting several thousandths runout at the end of the MT3 bore, a MT3 to MT2 reducer sleeve in it runs visibly out of true, as does the spindle nose flange. When you put a chuck on it, the runout is magnified by the distance from the spindle nose. Ideally we would replace the spindle when we change the bearings but its £52 [https://www.amadeal.co.uk/acatalog/4-Spindle-Upgrade-Real-Bull-Mini-lathe-CJ18-series-AMA_SP_CJ18_003RB.html#SID=9 from Amadeal] and money is tight. It may well require more work after the bearing upgrade. Once good bearings are in, if we can borrow a decent MT3 arbour as a reference, we should consider skimming the bore.<br />
<br />
===Spindle bearings===<br />
* The spindle bearings appear to be close to worn out. They are notably noisy when running, and there appears to be more slop in the spindle than is desirable. We have some ideas for possible replacement/upgrade, but it requires a major teardown.<br />
<br />
: The original bearings are allegedly 6206-2RS or 6206-ZZ deep groove ball bearings - 2RS codes rubber seals both sides and ZZ codes metal shields. Although the deep groove gives reasonable ability to withstand axial loads, the bearing balls point contact means they are vulnerable to [https://en.wikipedia.org/wiki/Brinelling brinelling] due to shock loading. The jammed on three jaw chuck didn't help this, as before we skimmed the spindle nose lip, it had to be driven off using a bar through the spindle bore, shock loading the bearings every time. Also even a minor 'crash' could have brinelled them due to eccentric shock loading, and the lathe has previously been crashed badly enough to need drive gear replacement. There are also issues with the 'approved' method of spindle and bearing removal from the headstock brinelling them, even if you don't abuse the spindle nose with a hammer!<br />
<br />
: A possible replacement is 30206 tapered roller bearings. The new bearings are slightly thicker so the plastic spindle spacer (15) needs to be machined to length to get the 45 tooth spur gear that drives the change gears laterally aligned with the tumbler gears. If a temporary replacement (3D printed?) is fitted, the lathe can be run (without power feed capability) so this can be done on the lathe after fitting the new bearings. As tapered roller bearings have line contact, they are significantly more resistant to brinelling.<br />
<br />
: ''See [[Talk:Ian_M%27s_Lathe_Notes]] for notes, links etc. for this upgrade.''<br />
<br />
===Motor stuttering===<br />
* Fixed 21/09/2023: The motor was running very erratically and it was very difficult to set a speed. Several loose connections were found in the control box, mostly loose female spades to the motor controller board, but also a dry jointed braking resistor on the 'Filter' board, and an inhibit wire completely off its terminal on the forward/reverse switch, making intermittent contact. After tightening and/or remaking all affected connections, it was much improved but still not right below 300 RPM. The remaining issues were due to poor wiper contact in the speed control pot, and stripping it, cleaning the track and contact ring and re-tensioning the contacts resulted in the motor now running smoothly over the full speed range. The speed is slow to settle, and while part of that is probably the lag in the digital tach, I suspect that the KBIC motor speed controller isn't properly tuned as it was (allegedly) previously replaced.<br />
<br />
===Drive belt slipping===<br />
* Fixed 28/9/2022: During testing the motor after the above issue, it was noted that the chuck could be stalled, slipping the drive belt, with not much torque. The drive belt was determined to be loose and a bit worn, but still in acceptable condition. <br />
<br />
: Access for servicing the belt requires removing the control box ''(2 spades to ZVR switch disconnect the supply, speed sensor and motor simply unplug from the 'filter board')'', the motor cover, chuck guard switch assembly + wiring cover, the change gear 'A' (drive) shaft carrier assembly, and the tumbler gear assembly. See https://youtu.be/EkxlIz01BdA for disassembly/reassembly, though on our lathe, the speed encoder ring on the spindle prevents the belt cover from being fully removed without disturbing the spindle nuts. There is enough room to work with it loose, but still trapped by the encoder ring. Also, unlike the video, if the 'jack' screws under the headstock are correctly adjusted, and the studs aren't excessively bent, there is no need to make custom studs. <br />
<br />
: It turns out that our lathe was missing the M6 hex headed jack screws that press the motor down to resist the belt tension, and the motor had cocked out of position at a severe angle. I know Ian B had had considerable trouble adjusting it after the motor fault back in October 2022, and I believe it had been getting slowly worse ever since. The jack screws were probably mistaken for headstock fixing bolts during disassembly after the crash that resulted in the metal Hi/Lo gears being fitted, then lost. The penny washers on the studs had dished, so I turned them over and backed them up with smaller washers and switched to nyloc nuts so they cant back off due to vibration. N.B. there is a packing washer on the motor side on one of the studs, presumably so the shaft is true to the ways. Adjusting the motor is awkward to say the least. One has to slack the stud nuts off a lot, pry under its rear end to lift it enough to be parallel to the ways, snug the stud nuts, check alignment, then set the jack screws and their lock nuts to hold it there, and finally tighten the stud nuts. <br />
<br />
: Tension: According to Sieg, it should be possible to twist the belt 90° mid span with a light finger grip. Other sources say 1/32" - 3/32" deflection mid span with light finger pressure.<br />
<br />
===Speed display blanking===<br />
* The speed display has been intermittent, blanking and flashing 8888 and 0 at certain speeds for as long as I have been using the lathe. Finally on 18/07/2022 it failed completely, with no display. I removed the display module and bench tested it - the pins are labelled 5V GND PL PE, PE is frame ground and PL is a TTL level pulse from the speed sensor - confirming that it was in good working order. My suspicions then turned to its power supply on the 'Filter' board. With both the sensor and display unplugged, the 5V rail was found to have a only a couple of volts, but the unreg DC was 17V and stable. Replacing the 78L05 5V regulator restored the 5V rail and normal operation.<br />
<br />
: ''I conclude its been failing for a while with high load current due to speeds with more lit segments causing it to drop out, resetting the speed display, causing it to blank, lowering the current enough for the regulator to recover, then the display MCU lamp tests (8888) then re-acquires the speed, repeating ad-nauseum till the speed is changed. I don't like the design as the high input voltage results in excessive dissipation.'' <br />
<br />
: ''ToDo: Bench test display to measure its worst case current consumption, then fit an appropriate dropper resistor to reduce the 78L05 dissipation.''<br />
<br />
===Quill spinning when drilling===<br />
* The quill was tending to spin while drilling because its anti-rotation pin (a M5 dog tip setscrew) was sheered. I've removed the debris, aligned the scale with the top of the tailstock and fitted a longer M5 dog-tip setscrew to replace it, with a nut to lock it at the correct height. N.B. the pin isn't that 'meaty' so if using big drills in tough metals, to prevent shearing it, it should be backed out so the quill can be turned by hand and unwanted rotation controlled by being quick with the quill lock if it starts to spin, or even using a close fitting rod in one of the chuck key holes with plastic tube over it to protect the ways. <br />
: ''If the screw sheers again, the quill will need to be removed and the tailstock taken off the lathe so the sheered tip can be shaken out, and if the setscrew is difficult to remove it probably means the threads are mangled where it sheered. Try driving it right through with the quill out.''<br />
<br />
===Sloppy quick change toolpost locking mechanism===<br />
* Once the dovetail clamp screw was slackened, there was nothing preventing the dovetail twisting or cocking significantly, and friction with the toolholder made it tend to do so, making toolholder insertion and removal more difficult unless the clamping screw was backed off excessively. I added a compression spring around the clamp screw inside the toolpost to push the dovetail outwards so it mostly retains alignment when open, allowing toolholders to slide on or off cleanly with far less screw slackening.<br />
<br />
===Leadscrew rubbing===<br />
* The leadscrew shaft is rubbing on the insulating separator inside the control box. Unfortunately the corner of the relay on the Filter Control Board (#160) doesn't allow enough clearance. Although the friction isn't much of a problem at high reduction ratios, e.g. 16:1 power feed, it increases the stress on the change gear train, and may be problematic when threading at feeds above 1:1. ''Possibly pack out the control box mountings by a couple of mm.'' <br />
<br />
===High/Low lever backwards!===<br />
* The high-low drive gear selector behind the headstock is incorrectly labelled and differs from the manual: low gear (which we normally use) is with the lever towards the tailstock. ''I suspect that the gears in the headstock were refitted the wrong way round when it was upgraded to metal gears.''<br />
<br />
: ''ToDo: Get it reassembled the right way round during the spindle bearing upgrade!''<br />
<br />
===Carriage lock fouls top slide===<br />
* The T handscrew has been replaced with a M5 hex headed bolt, to permit access when the top slide is over it. An 1/4" drive 8mm socket is usually left on it, but needs to be removed when the full cross slide travel is needed. The small (4 jaw) chuck key is near enough 1/4" to use for it. If you need to (un)lock it while the compound is over it, you'll need an 8mm spanner. ''The [https://www.amadeal.co.uk/acatalog/Mini-Lathe-Carriage-Lock-463.html Amadeal lock screw] is in the spares tin as it was too high and fouled the compound slide.''<br />
<br />
===Tailstock locking lever loose===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock - See full image for key to screws]]<br />
* Diagnosed and fixed 10/1/2023 - In the base of the upper section of the tailstock, there are two dog tip set screws that engage with locating grooves in the counter-rotating shafts carrying the eccentric locking cams. They'd backed off, probably due to vibration. They need to be tightened till they bottom out in the groove, making sure they are '''in''' the groove, backed off half a turn so the shafts can turn easily, and locked in place. There's no facility to do so, so reassemble with weak threadlocker. Unfortunately to get to them you have to remove the tailstock base slide, which is held on by the pressure of four adjusting grub screws, which all need backing off, and one socket headed bolt from underneath so full tailstock realignment is required after reassembly, which even for a rough alignment is tedious.<br />
: <s>The tailstock locking lever is loose and can be pulled out on its axis. It works OK when fully pushed home but needs investigating. ''I tightened the grub screw as the lever was coming off its shaft, but the whole shaft pushes/pulls in and out. It works OK fully pushed in, but it seems something that is meant to retain it has failed inside the tailstock base.</s><br />
<br />
===Gear alignment issues===<br />
* Change gear alignment is poor. I've currently got a gapped washer (to clear the key) packing out the A shaft so the gears line up, but this reduces the key's engagement so is problematic due to the high loading if the gears are set up for coarser threads. <s>Also I need to turn down some penny washers to slightly less than the root diameter of the metal 20T pinions, as gear retaining washers.</s> ''The gear retaining washers for A gear and B-C stub shaft are now done, turned down to slightly under 16 mm dia. Spares in the change gear tin. ToDo: The D (leadscrew) washer requires a larger center hole, so make two more with that hole.'' <br />
<br />
===Saddle gibs loose===<br />
* Fixed 11/04/2023: I took the apron off for access (and to clean the carriage handwheel gears), and found the front sheer plate screws were completely loose. I've snugged them up some and set the opposing grub screws and got a lot of the slop out. I've re-checked the front ones, and taken up the slop in the rear ones - Unfortunately it wasn't possible to get carriage movement to have an even 'feel' over its whole travel, and its noticeably tighter near the tailstock. If light hand pressure on the side of the unlocked carriage can cause movement (with the half-nuts open), its time to readjust them again, though it should be possible to move the carriage with a firm push. <s>The saddle gibs (actually the sheer plates) were too loose, to the point that engaging a slightly stiff threading dial could cause it to self-feed, an obvious crash hazard if working near the chuck or a step in the work.</s><br />
<br />
''N.B. the lefthand front opposing grubscrew is short, (fully recessed) and unlike the others does *NOT* have a locking nut as it must clear the traverse pinion. A wrap of PTFE tape provides enough friction to keep it in place, though possibly a bit of nylon fishing line down its hole would be better.''<br />
<br />
===Excessive cross-slide backlash===<br />
* ''Mostly Fixed <s>11/10/2022</s> again 07/11/2023:'' The cross-slide screw had excessive backlash (nearly three turns), possibly due to end float, which increases the risk of loosing track of the cut depth during threading operations. If you ended up off by a turn too far in, a crash was the most likely outcome.* 02/11/2023: The backlash is back up to one turn. I suspect the cross-slide screw nut mountings are working loose again.<br />
<br />
: So it turned out that the reason the cross-slide had nearly 3mm of backlash wasn't end float, it was loose cross-slide screw nut mountings. The nut has two socket headed cap screws pulling up, one either end, accessible from the top of the cross-slide, which control the tilt of the nut to take up backlash in the nut, and an opposing grub screw pressing down on the center of the nut to make it longitudinally rigid. I gambled the cap screws weren't too far out and snugged up the grub screw, and that immediately took out over 95% of the backlash which is now down to 10 divisions or so, or 0.25 mm. Shimming the cross-slide screw collar should take out some of what's left and careful adjustment of the nut tilt should get that down to under 0.1mm.<br />
<br />
: 07/11/2023: When the problem recurred I investigated further . It is difficult to get the cross-slide nut aligned correctly as it must be at the same height as the screw which is constrained by the bearing surfaces in the bracket. With the cross-slide almost at the front limit of its travel, I removed the screw and set the nut as level as possible and visually centered in the bore, then re-fitted the bracket and screw, then adjusted the tilt till it turned freely through the backlash. I then tilted it up at the front till some drag was felt to minimise the backlash and tightened the screws to lock it in place balancing them to maintain the same feel as I tightened them. The result was 7 divisions of backlash, acceptable but not great. During normal turning operations, the load on the nut is tension on the front screw and pressure on the grubscrew, so if it slackens again due to vibration from chatter, odds are it will be the rear screw that's loosened. <br />
<br />
* Further reduction of backlash: https://youtu.be/Wu_tI29JL2Y?t=163 <br />
: Brass tinned with Pb-free solder to form a white metal bearing surface should work at least as well as the bronze used in the video. The shim washer needs to be 10 mm ID and ~14 mm OD. It isn't necessary to remove the lead screw from the cross slide, as the washer can be fitted in-situ with only the bracket removed. Its also possible to closely estimate the required washer thickness from the backlash - note the number of dial divisions of backlash, then strip down the dial and bracket and with the gibs tight enough to keep the cross-slide from moving, push and pull the screw to assess its end float. A dial indicator mounted on the cross slide probing the screw flange will give you the total end float. Subtract the end float from the backlash, than take off another thou (0.025 mm) for running clearance to get the washer thickness (assuming it seats fully in the recess). If after fitting it, snugging up the bracket screws makes the screw too stiff to turn, the washer is too thick - either make another one or try to lap it down.<br />
: TLDR: measure flange on cross-slide screw and depth of recess in cross-slide bracket (behind dial) and machine a shim washer to take up nearly all the difference.<br />
<br />
===3 Jaw chuck didn't mount properly===<br />
* Fixed 7/4/2023 by grinding the spindle nose lip. The three jaw chuck can now be installed and removed by hand with no hammering. A test bar in it now has only 2 thou runout (TIR) at the chuck.<br />
: <s>The three jaw chuck and the faceplate aren't seating properly on the spindle nose. Its too tight on the register diameter of the lip. This results in grossly excessive runout, and also makes this chuck and the faceplate a PITA to fit or remove.</s><br />
: ''The spindle nose had been abused with a hammer (before my time) which mushroomed it and may have brinelled its bearings. See '''Excessive Runout''' and '''Spindle bearings''' above.''<br />
<br />
== Manuals, Books and other resources ==<br />
=== Manuals ===<br />
The [https://wiki.richmondmakerlabs.uk/images/a/a3/Lathe_InductionNotes.pdf RML CJ18A Mini-Lathe Induction Notes]. Your mandatory Lathe Induction will cover most of this but its good to be able to refer back to it.<br />
<br />
Official [https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Amadeal CJ18A Manual], or paper copy (less complete) kept on shelf above lathe.<br />
<br />
The [https://www.chesterhobbystore.com/wp-content/uploads/2022/11/Conquest-Super-Lathe.pdf Conquest Super Lathe manual] is considerably better than the Amadeal manual and is for a near-identical machine.<br />
<br />
The [https://littlemachineshop.com/images/gallery/info/minilatheusersguide.pdf Mini Lathe User’s Guide] from LittleMachineShop.com is even more comprehensive, going into its usage in some detail, with a proper TOC, and covers both US and Metric versions of Realbull Mini-lathes. ''The only fly in the ointment is the threading section assumes a US lead screw so change gear selections and threading dial divisions will not be correct for our lathe.''<br />
<br />
[https://www.arceurotrade.co.uk/machineguides/C3-Mini-Lathe-Dismantling-and-Reassembly-Guide.pdf Sieg C3 Mini-lathe Dismantling and Reassembly Guide] "A picture story book to help you dismantle and reassemble your Sieg C3 Mini-Lathe" ''It is similar enough to ours to serve as a maintenance guide, except for the electronics, spindle drive and other headstock innards.<br />
<br />
The motor controller is a clone of a [https://acim.nidec.com/drives/kbelectronics/-/media/kbelectronics/documents/dc-drives/manuals/kbic_manual.ashx?la=en KBIC® SCR DC Motor Speed Control]<br />
<br />
=== Books ===<br />
'''Metal Turning on the Lathe''', by David A Clark, Crowood Metalworking Guides, ISBN-13: 978-1847975232 [https://www.amazon.co.uk/gp/product/B00E78RKIG Kindle Edition (£8.99)]. ''A 'free' epub can be googled for, *NOT* linked here due to dubious legality.''<br />
<br />
'''[https://archive.org/details/03screwcuttinginthelathe Screwcutting In The Lathe]''', by Martin Cleeve (a pen-name of Kenneth C Hart), Workshop Practice series #3, ISBN-13: 9780852428382<br />
<br />
'''[https://archive.org/details/15workholdinginthelathe Workholding in the Lathe]''', by 'Tubal Cain' (a pen-name of Tom Walsh), Workshop Practice series #15, Argus Books, ISBN-10: 0852429088<br />
<br />
'''[https://archive.org/details/20metalworkandmachininghintsandtips Metalwork and Machining Hints and Tips]''', by Ian Bradley, Workshop Practice series #20, ISBN-13: 9780852429471<br />
<br />
'''[https://archive.org/details/38toolandcuttersharpening Tool and Cutter Sharpening]''', by Harold Hall, Workshop Practice series #38, ISBN-13: 9781854862419<br />
<br />
'''[https://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpaperT204.pdf Cutting Fluids]''', by EC Bingham, NIST Tech. Paper No. 204, 1921<br />
<br />
=== WWW resources ===<br />
==== Mini-lathe Specific ====<br />
There's a *LOT* of mini-lathe info online. Notable sites include:<br />
* http://www.mini-lathe.com/ - A major Realbull/Sieg mini-lathe resource.<br />
* http://mikesworkshop.weebly.com/lathe-modifications.html - many mods including carriage DRO autostop, and variable speed leadscrew motor drive, cross-slide motor drive, etc. He also has a page with a bunch of accessories, toolholders etc. - http://mikesworkshop.weebly.com/lathe-accessories-and-tooling.html<br />
* http://andysmachines.weebly.com/variable-speed-controls.html - Scroll down to the 'UPDATE' section for the schematic of a very similar SCR speed control board. It also has the schematic for an earlier version of the Auxiliary Control Board (aka: 'Filter' board).<br />
<br />
==== Forums ====<br />
''with publicly accessible archives''<br />
* https://groups.io/g/7x12MiniLathe - Mini-lathe specific, active<br />
* https://www.hobby-machinist.com/forums/mini-lathe-mini-mill-information.220/ - active<br />
==== Youtube Playlists & Videos ====<br />
* Blondihacks: [https://www.youtube.com/playlist?list=PLY67-4BrEae9Ad91LPRIhcLJM9fO-HJyN Lathe Skills] (playlist) - "This is an educational series to help you learn to use your metal lathe. Watch them in order for best results! Satisfaction not guaranteed, especially if you're a cranky sort of person."<br />
* Frank Hoose (Minilathe.com) has a couple of relevant Youtube playlists:<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn7ON0jGM5UbM-KZDT56MOIp Mini Lathe Operations]<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn4nGRZaVq3wTOlvZNOmdAZ2 Mini Lathe Overview]<br />
<br />
==== General Machining ====<br />
* https://www.machiningdoctor.com/ - "THE #1 MACHINING TECHNICAL HUB"<br />
<br />
==Projects==<br />
[[File:VESA mount.jpg|thumb|Machined VESA mounting plate (left) and plate from Dell monitor stand it must match (right). The translucent washer shows the size of the original center hole.]]<br />
* My first faceplate project was boring out the center hole in a VESA mounting plate to adapt it to fit onto a surplus Dell 1708FP monitor stand. The part was centered using the tailstock dead center engaging with its original center hole. I clamped the part with studs and penny washers on the driving side of two opposite corners, with cap screws in the next slot round to trap the corners under the clamping washers, then withdrew the tailstock and dead center. After machining out the bore, I used the tip of the tool, rotating the chuck by hand, to scribe a circle for laying out the bolt holes. I finished off laying out and drilling the bolt and locating holes by hand at home, fitted it to the stand, and mounted the 2nd hand LG 24" widescreen monitor.<br />
<br />
* Another ultimately unsuccessful project was fly cutting aluminum flat bar to thickness to make custom shims for the set of carbide insert tools, for the four way toolpost. The 8 mm shank tools need ~2.5 mm shim stacks, and the 6 mm shank tools need ~4.5 mm shim stacks. Ideally I'd machine single shims, but the only stock I've got handy cleans up to only 3.2mm, and some fine shimming may be needed to fine-tune the tool height.<br />
<br />
: After sorting out the clamps so they were no longer twisting the aluminum flat bar stock, and switching to the short 45° turning SCMT06204 insert tool in the four way toolpost, to improve rigidity and get a well controlled tip radius, the finish was much improved. I'm still having problems getting an even thickness and am getting approx. 0.05mm variation, I suspect due to the aluminium bar stock distorting due to internal stresses as its surface is cut away. ''ToDo: try supergluing the stock to the faceplate before clamping to further reduce chatter and stop the warping.''<br />
: Looking back on this project a year later, its fairly obvious that the thickness variation was probably due to faceplate surface runout due to the damaged spindle nose.<br />
<br />
* Raphael has been working on a steel rocket nozzle with some assistance from myself. We have set up the rough cut chunk of ~ 50mm steel bar, faced both ends (to 50mm length) and turned the OD to 49mm to clean it up. Its going to need through drilling, probably some boring, and quite a bit of detail work on the OD. It will then need to be transferred to a jig in the drill press vice to allow a pattern of angled traverse holes to be drilled with acceptable accuracy.</div>IanMhttps://wiki.richmondmakerlabs.uk/index.php?title=Ian_M%27s_Lathe_Notes&diff=17581Ian M's Lathe Notes2023-11-14T22:25:48Z<p>IanM: /* Notable Accessories */</p>
<hr />
<div>''Back to [[User:IanM|Ian M's profile]]''<br />
<br />
''Currently these notes are semi-organized and non-authoritative. As I become more experienced with the RML CJ18A mini-lathe, I'm cleaning up, extending and reorganising them. Some lathe operating experience is assumed. If in doubt, '''*ASK*''' me, Andy H<sup>*</sup> , Jonathan H or another experienced minilathe operator!<br />
<br />
''* Andy H should be asked (for an authoritative answer) any questions involving RML usage policies or acquiring tooling or materials through RML.''<br />
<br />
== The Lathe ==<br />
Our Facilities page [[Facilities#Lathe|has]]:<br />
<blockquote><br />
'''Lathe'''<br />
[[File: Lathe2.jpg |200px|right | Lathe]]<br />
In the kitchen. <br />
<br />
Marked as a CJ18A Mini-Lathe from [[https://www.amadeal.co.uk/acatalog/CJ18A-Mini-Lathe-7x14-Machine-100mm-3jaw-Metric-With-Metal-Gears-AMA_LA_CJ18_M_3_MGRB.html Amadeal]]<br />
[[https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Manual]] <br />
<br />
[[Media:Lathe InductionNotes.pdf| Induction Document]]<br />
<br />
Possible upgrades:<br />
*https://www.youtube.com/watch?v=GwT-JQLbNPA<br />
<br />
''Please do not use the lathe until you have received induction'' <br />
<br clear=all><br />
</blockquote><br />
Its a Chinese import 7x14 mini-lathe. The 7x14 refers to the maximum diameter and length of work, in inches and is only a theoretical measure of the working envelope as you loose length to the chuck + any tailstock tooling, and the diameter is over the bed, not the cross-slide. See actual specifications below. <br />
<br />
Most if not all Chinese 7x10 to 7x16 mini-lathes seem to be remarkably similar (not uncommon with Chinese products due to [https://www.bunniestudios.com/blog/?p=284 Shanzhai (山寨)] )<br />
and the OEM of our Amadeal CJ18A Mini-Lathe was probably [https://www.made-in-china.com/showroom/cheap-lathe Yangzhou Realbull Machinery Co. Ltd]. Very similar lathes are also made by [https://www.siegind.com/lathe-machine.html Sieg], but their lathes tend to be slightly less sophisticated than the equivalent Realbull models.<br />
<br />
''N.B. Many Sieg parts are known to have slight but critical differences from Realbull parts, so '''DON'T''' order Sieg spares for a Realbull lathe!<br />
<br />
== Key Specifications ==<br />
Amadeal says the CJ18A Mini-Lathe is a 7x14 model with:<br />
<blockquote><br />
* Power 550 W<br />
* Distance between centres : 350 mm<br />
* Swing Over Bed: 180 mm<br />
* Swing Over Cross Slide: 110 mm<br />
* Taper: MT3<br />
* Tailstock Taper: MT2<br />
* Chuck diameter: 100 mm<br />
* Spindle Speed: 50 - 2500 rpm ''(with digital readout)''<br />
* Spindle Bore: 20 mm<br />
* Cross slide Travel: 65 mm<br />
* Range of Metric Threads: 0.5 - 2.5mm.<br />
</blockquote><br />
* The lead screw is metric, pitch 1.5 mm.<br />
* The spindle center is 90.6 mm above the flat of the bed (measured).<br />
<br />
Even though the compound and cross slide handwheels appear to be calibrated in thousandths of an inch, as ours is a metric machine, they only approximate that. One turn of a slide handwheel is 1mm advance, and they have 40 divisions, so each division is 0.025 mm, (approx. 0.984 [https://en.wikipedia.org/wiki/Thousandth_of_an_inch thou]). Similarly, the tailstock quill advances 1.25 mm per handwheel turn, which has 50 division dial, giving the same 0.025 mm divisions, but only 4 turns per 5 mm. The carriage handwheel is awkward - it moves approx. 19.2 mm per turn, and doesn't have a dial scale.<br />
<br />
== Notable Accessories ==<br />
We have:<br />
* [https://www.amadeal.co.uk/acatalog/160mm-Face-Plate-for-the-4-Mini-lathe-AMA_AC_CJ18A_FP160RB.html#SID=129 160 mm (6 1/4") Faceplate]<br />
* 100 mm (4") three jaw self-centering chuck (OEM standard) 22.5mm bore, with inside and outside jaw sets<br />
* 100 mm (4") four jaw (independent) chuck with reversible jaws (8 TPI screws)<br />
* Tailstock drill chuck (max. 13 mm dia.)<br />
* Live center for tailstock (+ OEM fixed center) <br />
* Four way Tool Post (OEM Standard)<br />
* [https://www.amadeal.co.uk/acatalog/Quick_Change_Tool_Post_for_the_mini-lathe.html Quick Change Tool Post] + 3 tool holders<br />
* [https://www.amadeal.co.uk/acatalog/Fixed-Steady-for-Mini-Lathes-AMA_AC_CJ18A_FSRB.html#SID=145 Fixed Steady Rest]<br />
* [https://www.amadeal.co.uk/acatalog/Travelling-Rest-for-Mini-Lathes-AMA_AC_CJ18_TSRB.html#SID=144 Travelling Steady Rest]<br />
<br />
''You'll find all of the above on the shelf above the lathe, with the accessories in the wooden box, apart from the steadies, which live next to it. Change gears, spare parts, and most cutting tool tips/blanks are in labelled white rectangular tins behind the lathe.''<br />
=== Measuring Tools ===<br />
We have:<br />
* Various dial indicators - the one with the adjustable magnetic base stand is the most convenient for most lathe setup work.<br />
* 25mm micrometer (in little grey case)<br />
* Grey case containing set of measurement tools including dial calipers, micrometer, steel rule (metric & inch), engineers square, and a fish-tail gauge<br />
<br />
''We currently lack''<br />
* ''A tool height setting gauge''<br />
<br />
=== Hand Tools ===<br />
Some common tools needed for normal use are kept with the lathe, in or attached to the wooden accessories box:<br />
* 2 mm Allen key - adjusting cross-slide and compound gibs<br />
* 4 mm Allen key - quick change toolholder tool clamping screws + height adjust, tightening dials<br />
* 5 mm Allen key - four way toolpost tool clamping screws, engaging/disengaging threading indicator<br />
* 6 mm Allen key - locking/unlocking quick change toolholder<br />
* 8 mm spanner - locking carriage when 8 mm socket can't be used, locking gib adjuster nuts <br />
* 13 mm spanner - changing chucks, locking steady rest jaws<br />
* Very long needle nose pliers - for grabbing swarf safely, holding one end of emery cloth safely so you can keep your fingers away from the jaws, and extricating small objects from awkward places.<br />
<br />
== Change Gears ==<br />
[[File:BC puller 1.jpg|thumb|Custom puller for B-C stub shaft]] [[File:BC puller 2.jpg|thumb|Pulling the B-C stub shaft]]<br />
See "Conquest Super Lathe" manual ([[#Manuals|below]]), section '''4.7 Change Gears''', PDF pages 28-29, but see below for mesh adjustment. The LittleMachineShop.com "Mini Lathe User’s Guide" (also below) section '''Threading''' gives a far better explanation, with pictures and diagrams, but its for a lathe with a US 1/16 inch pitch leadscrew, not a metric 1.5 mm pitch one like ours, so you *MUST* ignore all the tables in that section, replacing them with metric mini-lathe (with 1.5 mm pitch leadscrew) equivalents. <br />
<br />
We have the following tooth count gears: 20,20, 30, 35, 40,40, 45, 50,50, 60,60, 80,80<br />
which consist of the OEM power feed gears + the metric change gear set. Apart from the metal 20 tooth pinions, they are all plastic, probably Delrin if the molded in 'POM' marking can be trusted, but possibly plain Nylon 6, and are metric Module 1.<br />
<br />
If we wanted to add the capability to cut US/Imperial threads we'd need to buy additional 55, 57 and 65 tooth gears, and possibly a 21 tooth metal pinion.<br />
<br />
CGTK's [https://www.cgtk.co.uk/metalwork/calculators/changegears/minilathe?gears1=20,20,30,35,40,40,45&gears2=50,50,60,60,80,80&gears3= Change Gear Calculator] ''(link preloaded with our gear list)'' is useful if you don't want to calculate the ratios from first principles. Not all suggested combos will physically fit.<br />
<br />
* Take care *NOT* to loose the keys in the A and D shaft keyways - turn each shaft till the keyway is up before removing the gear. <br />
* The B and C gears are coupled by a hollow stub shaft (with an integral key), which is so tight in the gears it has to be pressed or driven out - I've made a puller just for this task, kept in the change gears tin.<br />
* The center of the B-C stub shaft *MUST* be lubricated where it runs on its pin on the change gear banjo bracket, with grease or heavy oil. ''Seizure of the stub shaft due to running dry is a frequent cause of catastrophic mini-lathe geartrain failures!''<br />
* Don't get oil on the change gears as it can cause plastic gears to crack. Only PTFE drylube or plastic compatible white grease should be used on their teeth. <br />
* Adjust the B-C pin position in the straight slot first to set the C to D gear mesh, tighten its nut, then swing the whole banjo about the D shaft boss to set the A to B mesh, and finally tighten the banjo clamping nut.<br />
* Check both gear meshes have running clearance by turning the chuck by hand enough to complete one full turn of the leadscrew, and by attempting to turn the intermediate gear(s) to assess backlash, If excessive resistance is felt or if there's significant backlash, readjust the gears. If you have difficulty judging the mesh, a strip of 80 gsm copier paper (approx. 0.1 mm thick) wound into the meshing teeth before tightening the stud or banjo will give appropriate clearance once removed. Once setup, check the gears run quietly under power.<br />
* If the sum of the tooth counts C+D is the same as for the ones you just removed and they were correctly meshed, you don't need to move the stub shaft pin. If A+B is <u>also</u> the same, you don't need to move the banjo. e.g. If it was set up for 16:1 reduction power feed, 1 mm (40:60 - 50:50) for M6 and 1.5 mm (e.g. 40:60:40) for M10 pitches can thus be achieved by only swapping gears. <br />
<br />
''The change gears, puller, etc. and a box spanner for the banjo nut are kept in a white rectangular tin behind the lathe.''<br />
<br />
=== Power Feed ===<br />
When used for turning with power feed, the change gears should be set for a 16:1 reduction (A:20 : B:80 - C:20 : D:80) using the pair of small metal 20 tooth pinions and the 80 tooth plastic gears (largest in set), for a feed of 0.09375 mm per turn (1.5 mm/16). Unless continuing your threading project the next session, please re-fit the 16:1 power feed set after threading so the power feed is ready for use. <br />
<br />
* *ALWAYS* leave the feed direction selector lever in its neutral (no feed) position, and the half-nuts open after use.<br />
* *ALWAYS* check the carriage lock is disengaged before engaging power feed. Unlock the carriage after use. <br />
<br />
=== Threading Dial ===<br />
The threading dial is an aid to re-engaging the half-nuts at the right moment so the tool will retrace its previous path cutting deeper, rather than offsetting axially some fraction of the thread pitch and ruining your work. Its based on the concept of the lowest integer multiples of the leadscrew and thread ''(being cut)'' pitches that exactly match, but for mechanical simplicity it only covers certain selected multiples of the leadscrew pitch.<br />
<br />
We have a choice of three pinion gears:<br />
{| class=wikitable<br />
|+ Threading dial Pinion Gears<br />
|-<br />
! Teeth !! Colour Dot !! Usable lines !! OD gear !! Dist. per turn<br />
|-<br />
| 14 || Red || 1,7 || 7.51 mm || 21 mm<br />
|-<br />
| 15 || Orange || 1,5,9 || 8.05 mm || 22.5 mm<br />
|-<br />
| 16 || Green || 1,4,7,10 || 8.37 mm || 24 mm (2 mm/div)<br />
|}<br />
They are now colour coded, with a paint dot on the gear end face ''(the only non-wear surface)''. The 16 tooth one is normally left on the lathe, but disengaged when not threading to minimise wear on the lead screw. The others are kept in the Change Gear tin.<br />
<br />
There's a threading dial 'pickup' calculator here: https://www.cgtk.co.uk/metalwork/calculators/threaddialindicator <br />
<br />
Initially select ''Lathe:'' '''Custom''', and enter the following below:<br />
* ''Units:'' '''Metric'''<br />
* ''Lead Screw Pitch (mm):'' '''1.5'''<br />
* ''Thread Dial Indicator Gear Teeth:'' '''16,15,14''' <br />
* ''Lines on Thread Dial Indicator:'' '''12''' <br />
* ''Line Marking:'' '''Every Line Numbered'''<br />
Note the teeth list is entered in reverse order so the resulting table highlights any required pinion changes.<br />
<br />
N.B. The dial is only friction clamped to the pinion by its center screw. If you have any reason to suspect it may not be properly aligned: <br />
# With the power off and the carriage unlocked, engage the feed direction lever upwards. You'll probably need to turn the chuck by hand to get it to engage.<br />
# If the threading indicator isn't already engaged, loosen the threading dial support block bolt, pivot the block to engage the pinion with the leadscrew and retighten the bolt.<br />
# Engage the half nuts, again turning the chuck by hand till they drop in. <br />
# Turn the chuck a couple of turns, top towards you to take up any backlash, then lock the carriage, taking care not to push it left while locking it.<br />
# Loosen the screw securing the dial to the pinion.<br />
# Align the '1' line of the dial with the index line, by rotating the dial clockwise, then retighten the screw.<br />
# Don't forget to disengage half-nuts and unlock the carriage!<br />
<br />
The above instructions should result in the half-nuts engaging cleanly when exactly on any valid line when threading towards the headstock. If it is required to thread away from the headstock, there will be a slight offset from the line due to backlash between the spindle gear and leadscrew, so engage slightly early.<br />
<br />
Changing the pinion:<br />
# Loosen the threading dial support block bolt and disengage from the leadscrew.<br />
# Undo dial center screw, and remove it and the dial, dropping the old pinion out the bottom.<br />
# Oil the shaft of the new pinion with a drop of light oil and insert it from below, gear end down.<br />
# Refit dial and screw.<br />
# Check the dial and pinion turn freely with minimal resistance.<br />
# Align as above.<br />
<br />
== Tailstock and Steadies ==<br />
These are mostly used to support long work ''(long with respect to its diameter)'' to improve rigidity, increasing accuracy and reducing chatter. The Tailstock quill is also used with a drill chuck for drilling.<br />
=== Tailstock ===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock base]]<br />
The tailstock can be offset to turn shallow tapers between centers. We don't currently have the accessories to turn between centers, namely <s>a MT3 dead center for the spindle, or</s> any drive dogs for the work. Also realigning the tailstock after turning a taper can be a PITA. The photo shows the tailstock adjusting screw locations ''(C - Lateral, and D - Skew)'' and the block on the baseplate they engage with. Adjustments can only take effect when the tailstock locking lever is eased to take the pressure off the baseplate. As we don't have a MT3 center, one has to turn a fresh point on a test workpiece for a rough tailstock alignment reference. Fine alignment, to avoid inadvertent taper turning, can be done by mounting a long precision ground bar between the chuck (or preferably a center in the spindle), and a dead center in the tailstock and sweeping it with a dial indicator on the carriage. Finally a test cut should be taken at either end of a bar between centers, and the diameters checked with a micrometer. Assuming the bed has previously been properly levelled and shimmed to take out twist ''(not the case at RML as we don't have it bolted down)'', any remaining difference in diameter will be double the tailstock offset, smaller at the tailstock being offset towards the front. Fine adjustment cant be achieved by jacking with the screws, its best to ease the adjusting screws, bump the tailstock into alignment then take up the screws again, checking the alignment is maintained when the tailstock is unlocked and relocked. There is no vertical adjustment, though shims can be added between the tailstock and its base.<br />
<br />
==== Tailstock Quill ====<br />
There is a metric/imperial scale on the top of the quill, read against the end of the tailstock, for depth measurement when drilling. The tailstock quill has a 1.25 mm pitch thread and a 50 division dial. Each division is therefore 0.025 mm, and it only takes 4 full turns of the handwheel to move the quill 5 mm. <br />
<br />
To eject MT2 taper tooling and centers from the tailstock, wind the quill all the way in.<br />
<br />
N.B. The quill anti-rotation pin (dog-tip setscrew + locking nut in top of tailstock near to the quill lock) is only M5. It will sheer if a large diameter drill jams in the work. Please back it out clear of its keyway if using large drills, and use alternative methods of preventing chuck rotation. To re-engage it, crank the quill out till you can see the keyway, align it with the screw and screw in the screw till it gently bottoms out, then back it off a quarter turn. Try twisting the quill to check its properly engaged, then tighten the locking nut gently to hold the screw in position clear of the bottom of the keyway.<br />
<br />
=== Steady Rests ===<br />
We have two, both with brass tips that must be kept lubricated during use.<br />
<br />
The fixed steady mounts on the ways, and is most useful when turning longer work that wont fit through the spindle bore. Adjustment is critical, and the surface the tips run on must be smooth and concentric, as any misalignment that forces the work off center will result in the work wobbling in the chuck, marring it, with a high risk of it becoming un-chucked, which can be dangerous at speed.<br />
<br />
The travelling steady mounts to the headstock side of the carriage to locally resist the deflection of thin long work, due to the cutting forces. It only has two tips, to resist climb, and deflection away from the tool, and requires readjustment after every cutting pass.<br />
<br />
== Tooling and Tool Holders ==<br />
'''Key dimensional data:'''<br />
* The quick change holders accept up to 10 mm shank tools. <br />
* The four way toolpost has 50 mm long sides, a seat width of 15 mm and can clamp tools of up to 5/8" (15.875 mm) shank ''(check this)'', but the slot base is only 10.4 mm below the spindle center so cannot be used with >10 mm shank tooling unless it has a dropped tip. Large tooling with a centered tip is also problematic as you run out of height above the shank when trying to shim to match the spindle center height. <br />
<br />
===Quick Change Toolpost===<br />
I've got the quick change toolpost and toolholders setup for mostly easy use. The three toolholders came with cantilever height setting arms which historically haven't been installed as the supplied fixing screws were too short. That's all now sorted out and a HSS RH turning tool and a HSS hand-ground grooving/parting-off tool are now mounted in two of the holders and set to height. The third is kept free for other tools. <br />
<br />
The quick change toolpost has been modified with a spring to press the dovetail clamp outwards and help stop it twisting or flopping about to ease toolholder fitting and removal. The dovetail clamp (socket headed screw on toolpost side opposite dovetail) feels a bit stiffer than before, but will take less than half a turn to go from open (with the toolholder lifting out or dropping in easily) to fully clamped. As there is so much less clearance in the open position you should no longer need to wiggle the toolholder while clamping it to get a consistent height. If the dovetail clamp ever gets misaligned, twist it straight by eye, slacken off a bit further than usual to get a toolholder on, clamp it to align the dovetail then release, reseat the toolholder and re-clamp to ensure its at its preset height. You cant adjust the height by 'jacking' with the height screw due to its offset leverage. Instead, back off the height screw and hold the toolholder at the desired height while locking the dovetail clamp, then adjust the height screw (and locking nut) to hold it there, then check it doesnt change height significantly when you unclamp and reclamp the dovetail. <br />
<br />
Unfortunately the OEM height setting screws foul the toolpost locking nut handle. Currently, if you need to swap toolposts you will have to first remove the quick-change tool holder from the post. There is enough nut handle swing to allow the quick change toolpost to be unclamped and rotated to fine set the tool angle without removing the toolholder. It also seems the mating surfaces may be slightly out of square, as if you rotate the toolpost 90° or 180°, the nut swing may be insufficient to re-clamp it without removing the toolholder to do so. Add a M10 washer under the locking nut if the handle ends up pointing in an undesirable direction! A thin M10 washer is kept with the toolpost collar for this purpose, and will shift the handle position by about a third of a turn. <br />
<br />
''ToDo: Make a taller nut of a similar pattern, to clear the height setting screws.''<br />
<br />
===Four Way Toolpost===<br />
The OEM four way toolpost is significantly more rigid than the quick change toolpost + holders because it has fewer and thicker parts and less overhang. Therefore the four way toolpost should be used when using carbide tooling. It requires shimming under the tool to set the tip height to the spindle center height - see below. The tool shanks are mostly significantly less than 15 mm wide, so need to be centered under its clamping screws, tempting as it is push the shank in for full side contact with the toolpost. If possible clamp the shank with all three screws not just two.<br />
<br />
==== Shimming ====<br />
We typically only mount up to two tools, and want maximum rigidity, so use 50 mm x 15 mm shims, (the full seat area), preferably with deburred edges and radiused corners so they aren't a hazard to the operator.<br />
<br />
We have pre-cut and marked shims of the following thicknesses: <br />
* 1x 3.23 mm, 2.42 mm, 1.56 mm, 0.32 mm, and 0.25 mm<br />
* 2x 1.00 mm, 0.77 mm, 0.12 mm, 0.11 mm, 0.10 mm and 0.05 mm<br />
* 4x 0.53 mm<br />
<br />
Our shims are mostly found materials (hence the awkward thicknesses) and are mostly a mixture of aluminium and steel, with a couple of GRP ones. The toolpost seat '''<u>must be absolutely clean</u>''' to avoid embedding debris in the aluminium or GRP shims, to get a consistent height and avoid tilting the tool - wipe it every time you change a tool! Put the thin shims at the bottom of the stack to avoid the tool shank edges creasing them. Shims are kept in a little yellow plastic box with a clear lid, near the carbide tools case.<br />
<br />
''ToDo:'' <br />
<br />
* ''Cut more shims neatly, mark them with their thickness.''<br />
* <s>''Do test cuts and start noting shim stack-ups for various tools.''</s><br />
* ''Organise shim storage!''<br />
* <s>''Possibly acquire, cut down and dismantle a feeler gauge set to get a better selection of marked steel shims.''</s><br />
* ''Make a tip height setting gauge''<br />
<br />
=== HSS Tools ===<br />
[[File:Tool Bit Geometry.jpeg|thumb|Single point cutting tool geometry]]<br />
Our HSS tools are made from 8 mm square bar stock, hand-ground to tip profile in-house. See LittleMachineShop's [https://littlemachineshop.com/images/gallery/instructions/grindingtoolbits.pdf Grinding Tool Bits] notes. <br />
<br />
I've installed our usual HSS LH turning and parting off tools in two of the quick change holders and set the heights correctly. There are a couple of other HSS tools or tool blanks knocking about. Taking heavy cuts turning steel (even with good cutting oil) blunts HSS tools fairly quickly, which are time-consuming to re-sharpen nicely without a dedicated tool & cutter grinder with appropriate jigs. Its worth noting that the usual 'speeds & feeds' tables are commonly based on surface speeds expected to give a half hour (active cutting) tool life before resharpening.<br />
<br />
I touched up the LH turning tool by lapping on wet & dry (silicon carbide) paper on glass (Aka: [https://en.wikipedia.org/wiki/Scary_sharp 'Scary Sharp']) working upwards through the grits 200, 400, 600 and finally 1000, initially 'bluing' the surfaces to be lapped with a marker pen to see which areas needed taking down more. The end of the tool was significantly uneven so I touched that up freehand on the bench grinder to flatten it when it became apparent that 200 grit lapping wasn't cutting where it needed to. There was an existing micro-bevel on the leading side, which I kept. Finally I 'dubbed' the leading corner vertical edge on the 1000 grit to give it a very slight nose radius. A test cut on brass gave a very nice finish when turning.<br />
<br />
''Ian B has purchased some spare 8mm HSS tool blanks - talk to a lathe trainer if your proposed lathe work needs custom ground HSS tooling.'''<br />
<br />
=== Brazed Tungsten Carbide Tools ===<br />
Somewhat of a half-way house between hand ground HSS tooling and insert tooling with the disadvantages of both and some more besides - e.g. they are much harder to sharpen. So why do we bother? Some tool geometries would be awkward and tedious to hand grind, and Chinese import brazed carbide tooling is about half the price of similar HSS tooling, and far more readily available. Also, for space constrained tooling like boring bars, if you want carbide, for insert tooling, the size of the insert and its clamping seriously limits the minimum hole diameter you can work in. I have purchased a set of 3/8" shank brazed carbide tipped boring bars, but we currently cant sharpen them, due to lack of a diamond grinding wheel. <br />
<br />
=== Tungsten Carbide Insert Tools===<br />
Decoding ISO insert tooling part numbers: https://www.cutwel.co.uk/blog/learn-the-turning-tool-iso-code-system<br />
[[File:Carbide set.jpg|800px|thumb|left|Our set of Tungsten carbide insert lathe tools (before the new inserts were fitted)]]<br />
<br />
{| class=wikitable<br />
|+ Tools, left to right, (+ last across top):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| SSKCR0610H06 || 75° through boring || SCMT06204 || Long || 6 || 6.34 || ''4.33''<br />
|-<br />
| SSSCR0610H06 || 45° deep facing, internal chamfering || SCMT06204 || Long || 6 || 6.13 || ''4.58''<br />
|-<br />
| SWUCR0610H05 || 93° boring, deep facing || WCMT050308 || Long || 6 || 6.22 || ''4.48''<br />
|-<br />
| SWGCR0810E05 || 90° RH turning & facing || WCMT050308 || Short || 8 || 8.25 || '''2.45'''<br />
|-<br />
| SSSCR0610E06 || 45° turning, chamfering || SCMT06204 || Short || 8 || 8.75 || ''1.93''<br />
|-<br />
| SSBCR0610E06 || 75° RH turning, chamfering || SCMT06204 || Short || 8 || 8.72 || ''1.98''<br />
|-<br />
| LW0810R-04 || 60° external threading || JCL15-120 || Short || 8 || 7.44 * || ''3.28''<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || 8.23 || ''2.5 ?''<br />
|-<br />
| LN0813R-04 || 60° internal threading || JCL15-120 || Long || 7.95 || 7.44 * || ''3.28''<br />
|}<br />
<br />
{| class=wikitable<br />
|+ More Tools, (loose in tin):<br />
|-<br />
! PartNo !! Description !! Insert !! Shank !! Shank H/mm !! Tip H/mm !! Shim H/mm<br />
|-<br />
| QA0812R-03 || grooving, parting off || CK3 || Short || 8 || ~8.5 (not in use) ||<br />
|-<br />
| [https://www.glanze.co.uk/product/glanze-12-mm-60-degree-metric-internal-threading-tool/ Glanse SIR0012K11] || 60° internal threading bar || 11IRA60 || Long || 12 dia || ??? || ???<br />
|}<br />
''Shim stack heights in bold are tested, in italic are only calculated.'' ''Tip heights marked * are with new JCL15-120I inserts. The single remaining plain JCL15-120 insert has a slightly higher tip height.''<br />
<br />
Carbide tooling typically requires two to three times more speed than HSS and at least a couple of 'thou' depth of cut for best results.<br />
<br />
Chatter can rapidly kill carbide tooling by chipping the cutting edge. To improve rigidity and reduce the risk of chatter, the cross-slide and compound gib screws need to be well adjusted so there is minimal play in the slides, tool stick-out should be minimised, the four way toolpost should be kept over the cross-slide, and the work should be kept close to the chuck (or otherwise supported by tailstock or steady rest) to avoid excessive deflection.<br />
<br />
Thermal shock is almost instant death to carbide, and when dry cutting the insert tip can run very hot, so do not add extra cutting fluid manually during the cut. Pre-apply what you need, evenly, before starting the cut.<br />
<br />
Parting off or facing to center is high risk - if the tool tip is even slightly below center or if tool or work deflection takes it below center, the work will tend to climb over the tool tip as the cut approaches center, breaking the insert. To avoid this, the tool should be shimmed slightly above center, sufficient to allow for work and tool deflection, and unless very close to the chuck, a steady should be used. Its often preferable to part to a couple of mm dia. remaining then stop and saw through the remainder. Parting off hollow parts is much lower risk.<br />
<br />
Further investigation of the Tungsten carbide insert tool height situation is not encouraging - the so-called 'set' in question does not have a consistent tip height ''(see above table)''! In a real set, the insert seats *should* be machined allowing for the insert thickness to bring all the cutting edges to the same height with respect to the shank underside. However if you place them tip to tip on a table its easy to see there is considerable height variation, so they need to be individually shimmed (or at best, one machined shim will only be right for two or three tools). At this time we don't have dedicated shim stacks for each tool.<br />
<br />
A 2.42 mm thick shim brings the SWGCR0810E05 90° RH turning & facing tool almost exactly to center height, and good results were obtained turning 1" steel pipe. However facing 50mm steel bar stock to center found it to be slightly low, leaving a fractionally under 0.05 mm 'pip' so it needs another 0.03 mm to bring it fractionally above center. Fractionally too high is generally preferable to fractionally too low, due to tool deflection, so adding an 0.05 mm shim to the stack should produce optimum results.<br />
<br />
==== Inserts ====<br />
Ian B has purchased the spare inserts we needed in sets of five. He even was able to get the CK3 parting-off inserts which had been difficult to source!<br />
<br />
Inserts used in above tool set:<br />
* 3x SCMT06204 (square, indexable) https://www.rdgtools.co.uk/acatalog/SCMT-06-Carbide-Insert.html<br />
* 2x WCMT050308 (triangular, indexable) https://www.rdgtools.co.uk/acatalog/WCMT-05-T3-08-5XTIP-8813.html<br />
* 2x JCL15-120 (60 deg threading point) https://www.rdgtools.co.uk/acatalog/X5-JCL-15-120L-THREADING-TIPS-60-DEGREE--X5-TIP---23455.html<br />
* CK3 (parting off) https://www.rdgtools.co.uk/acatalog/CK3-CARBIDE-TIPS---PARTING--BOX-OF-5PCS--9437.html<br />
<br />
Inserts used in other tools:<br />
* 1x CK3 (as above) also missing from spare parting off tool<br />
* 1x 11IRA60 in Glanse threading bar + 1x spare<br />
<br />
=== Drills ===<br />
Various sizes of center drills are kept in a plastic bag next to the wooden accessories tray. There's also a small box of 2.5 mm center drills.<br />
<br />
We have a set of 11 TiN coated HSS drill bits from 1.5 to 8 mm, (in a cylindrical plastic index box) for tailstock drilling of brass, aluminium and non-abrasive plastics. To keep them sharp enough for the precision work we expect from the lathe, please don't use them for steel or reinforced plastics, and don't borrow them for non-lathe use. Metric and US [https://littlemachineshop.com/reference/numberdrillsize.php numbered]/[https://littlemachineshop.com/reference/letterdrillsize.php lettered] general use HSS drill bits are kept in two red metal index boxes next to the drill press.<br />
<br />
== Using the Lathe ==<br />
=== General ===<br />
A cutting speed chart for HSS tooling, published by Model Engineer magazine can be found [https://www.model-engineer.co.uk/sites/7/documents/cutting%20speed%20chart.pdf [here<nowiki>]</nowiki>]. The second row is the target feed rate and the rest of the chart, apart from the diameter column is RPM.<br />
<br />
For carbide tooling cutting iron and steels, recommended speeds are generally three times higher than for HSS, but the CJ18A 2500 RPM max. spindle speed (in high gear) means you can only reach the optimum speed range for over 15 mm dia work. For small diameter work, HSS tooling may well be a better choice.<br />
<br />
An online metric speeds calculator is here: https://www.cgtk.co.uk/metalwork/calculators/cuttingspeeds <br />
<br />
How to do the maths to calculate speeds and feeds: https://www.cutwel.co.uk/blog/speeds-feeds-made-easy<br />
<br />
Making dimensioned parts is primarily done by touching off the tool tip on a reference surface (with the lathe stopped, turning the chuck by hand), zeroing the handwheel dial, then manually counting turns and divisions. When backing off the tool its best to do so by exactly one whole turn so you don't forget the previous dial position. Stopping and measuring the work before taking the final cuts is essential if high accuracy is required. ''I've changed out the dial setscrews for flat tip ones with a tiny slug of solder under them so the dials are now friction fit on their shafts. i.e. if you hold the handle firmly taking up the backlash in the direction of cut, you can zero the dial just by grabbing and twisting it.''<br />
<br />
Carriage movement is less easy to measure as the handwheel is uncalibrated and advances an awkward bit over 19.2 mm per turn. Your options here when shoulders or other features must be exactly positioned are, in order of increasing accuracy: <br />
* Use measuring instruments, scribe the work at the desired length then work to the scribed line. Its often convenient to black the work with a permanent marker, then scribe with the tool tip, turning the chuck by hand.<br />
* for short distances, lock the carriage and use the compound, set parallel to the work<br />
* Set up a long travel dial indicator to measure carriage motion. <br />
N.B. with the leadscrew stopped, and the threading dial engaged, with its default 16 tooth gear, it will make one turn for every 24 mm of carriage movement (2 mm/div). This isn't accurate enough for positioning but is sufficient to check you aren't out by a whole mm or more.<br />
<br />
Do not allow any solvents to contact the chuck guard clear plastic as it will make the plastic brittle, or even craze it, and try to avoid melting it with the work light!<br />
<br />
=== Slide Locks ===<br />
* The carriage can be locked to the ways using the M5 hex screw through the top of the saddle to the left of the cross-slide. Double check the leadscrew is disengaged and the half-nuts open before locking it. Lock it when facing.<br />
* The cross slide is drilled and tapped for a M4 locking screw, just in front of its middle gib screw, but currently no screw is fitted. Locking the cross slide is helpful when turning very shallow conical features where the cross slide handle is in the way of the compound.<br />
* The compound slide can be locked by a M4 socket headed cap screw in line with the edge of the toolpost mount on the side with the gib adjustment screws. In normal use it should be kept backed off half a turn but it is desirable to tighten it for parting off operations to keep the resulting end faces flat.<br />
<br />
=== Chucks and Chuck Jaws ===<br />
==== Terminology ====<br />
* Inside jaws have steps on the outside to grip the ID of hollow work, but can also be used as outside jaws on small diameter parts (i.e. that fit through the spindle). <br />
* Outside jaws have steps on the inside to grip the OD of the work.<br />
* Universal chucks have a scroll plate with a spiral screw thread that moves all the jaws.<br />
* Independent chucks have individual adjusting screws for each jaw.<br />
<br />
==== The Chucks ====<br />
* The three jaw universal chuck can only grip near round or hexagonal work, which it centers, but its concentricity is not perfect so e.g. if you reverse the work and continue turning at the same diameter from the other end, you will see a line where the turned surfaces meet. It has separate sets of inside and outside jaws, and we normally keep the inside set installed to use as outside jaws for small diameter work.<br />
<br />
** Our jaws are individually numbered, stamped in the groove. They must be fitted in the correct sequence. The jaw slots are not clearly marked. Lowest runout for small dia. parts is achieved if you fit the jaws with #1 anticlockwise of the makers mark, then continue anticlockwise for #2 and #3.<br />
** A large strong rubber band is a great help getting all the jaws started on the scroll together - with slots #1 and #3 above the centerline and the scroll thread outer tip between #1 and #3, insert jaws #1 and #2 and put the rubber band round them to keep them in their slots. Insert jaw #3 and stretch the rubber band over it to hold it up into its slot. If the scroll was positioned correctly, all jaws should be at the same initial radius. The jaws can now be cranked in with the chuck key and they should all engage in step so they meet in the middle.<br />
:: ''Mini-lathe.com have the best instructions for [https://www.mini-lathe.com/mini_lathe/chucks/chucks.htm#Installing_Chuck_Jaws changing the jaws].'' <br />
<br />
* The four independent jaw chuck can grip most roundish or squarish work, which can either be carefully centered by the user, or deliberately gripped off-center. <br />
** Its jaws are reversible so can be swapped from inside to outside by simply cranking each jaw out and reinserting it the other way round, one at a time. DON'T move the jaws to different slots as they are likely to bind.<br />
** When setting up to face the sides of rectangular objects held crossways, it may be helpful to use both inside and outside jaw orientations, in symmetrical opposing pairs.<br />
<br />
* The jaws must '''never''' protrude from the chuck OD by more than one step, and for safety, its preferable they don't protrude at all, as they make the gap between the front of the bed and the chuck body an even more unforgiving meat grinder, and as the number of teeth engaged with the scroll or screw decreases, they loose strength, just when you need it the most to grip larger/heavier work. <br />
<br />
''Neither chuck is well suited to gripping tapered work safely. When seating work that doesn't quite fit through the chuck bore (which is larger than the 20mm spindle bore limit), be careful that it isn't seating on the chamfered edge of the chuck bore as it is far to easy to get the work slightly cocked so it doesn't run true.''<br />
<br />
==== Changing Chucks ====<br />
* When changing chucks, use the small grey plastic mat to protect the ways under the jaws in case you drop the chuck.<br />
* The spindle nose has two patterns of holes - the three hole pattern is for the three jaw chuck and the faceplate, and the four hole pattern is for the four jaw chuck. One hole is shared between the patterns, and is marked on the spindle nose.<br />
* To fit a chuck:<br />
** First check that the spindle nose and chuck back and recess are free of swarf, grit or other debris. Any foreign objects will tilt the chuck causing excessive runout and may mar the surfaces.<br />
** Remove the nuts and split lock washers from its studs, line its studs up with the hole pattern (preferably with the stud nearest anticlockwise to the makers mark through the marked spindle hole), fit and hold it in place with your right hand, and with your left, get the lock washer and nut on the top stud, and take up the slack.<br />
** One one nut is on, you no longer have to worry about dropping it, and can work round fitting the remaining washers and nuts, taking up the slack on each as you fit it. <br />
** Next, work round again getting them all finger tight, then tighten them gently, and finally work round fully tightening them. <br />
* Removal is the reverse of refitting. Put the washers and nuts back on the chuck's studs so they don't get lost.<br />
<br />
=== Faceplate Work ===<br />
Faceplate work is probably the most dangerous operation you can (or rather should) perform on a lathe. The working area is a large diameter spinning surface with protruding clamps to fixture the part that it is impractical to guard. Protruding clamps, studs, nuts etc. are very difficult to see at speed.<br />
<br />
'''Treat the faceplate with great respect and caution if you wish to continue to be able to count to ten on your fingers!''' <br />
<br />
The 65 mm cross-slide travel vs the 80 mm faceplate radius is a serious limitation that may require creative compound, toolpost and tool setups for larger parts, and doing full face cuts in two sections.<br />
<br />
''It is common practice to skim the faceplate to ensure it runs true. We have not (yet) done this, and wont till the spindle is in better bearings and the nose reground to minimise runout.''<br />
<br />
==== Clamping ====<br />
Open ended/sided clamps should be oriented so that cutting forces drive the work towards the clamping bolt/stud, not out from under the clamp. Minimize the protruding length of thread past the clamping nut, if necessary using sacrificial bolts or studs you can cut to length, or even using a long M8 stud for one of the faceplate mountings, so you can get a clamp nearer to the faceplate center. Double-check all clamps are secure, manually turn the faceplate to check the work and clamps clear the ways, top-slide and toolpost, and stand out of the 'line of fire' (a disc extending from the faceplate) when spinning up the work for the first time. <br />
<br />
If you need to machine close to a clamp, consider marking a safe limit circle on the faceplate and work with a marker pen to make it easier to see how close the cutting tool is to crash disaster. <br />
<br />
I strongly advise reading chapter two of Tubal Cain's book "Workholding in the Lathe" several times before your first faceplate setup, and if possible get another experienced lathe user to check your first few setups before spinning them up.<br />
<br />
==== Chuck Guard Removal ====<br />
The faceplate is too large diameter to fit under the chuck guard, but the guard has an interlock switch wqhich must be closed for the lathe to run. The guard is now fitted with wing nuts so it can be removed allowing the the interlock switch to close when using the faceplate. It *SHOULD* *ALWAYS* be refitted if a chuck is fitted, except when turning work too large to clear the guard. <br />
<br />
''The chuck guard is primarily there to make it very difficult to start the lathe without removing the chuck key and to reduce the area of large diameter spinning surface exposed. It may slow down the projectile if a chuck sheds a jaw but is unlikely to stop it. Also it serves to contain coolant spray spun off the chuck. As we don't use flood coolant this usually isn't an issue for us. As setting up for faceplate work doesn't use a chuck key, and the most hazardous zone is the face of the faceplate, with its spinning projecting clamps, with full access required for machining operations, which a guard would not cover, the consensus is that removing the guard is an acceptable risk.''<br />
<br />
=== Turning and Facing ===<br />
We are getting good results in aluminium, brass, and even steel using HSS cutting tools in quick-change tool holders, and the ~ 94 um/turn power feed. Unfortunately due to lack of rigidity in both the machine and smaller diameter parts, if you don't want the outer end to be over diameter, a light final cut and multiple 'spring' passes will probably be required.<br />
<br />
For aluminium, a sharp HSS tool and 0.5 mm (20 div) depth of cut gives good results with power feed for rapid stock removal. Its also easy maths as each cut takes ~ 1 mm off the diameter. Finish cuts should be much finer, 0.1 mm (4 div) is 'in the ballpark'.<br />
<br />
For steel, using carbide insert tooling, a 0.25 mm (10 div) depth of cut is more appropriate, and with pre-applied cutting oil, gives reasonable results with power feed if you use enough speed. The maths is not quite so easy as you are only taking 0.5 mm off the diameter per pass. Again, use finer finish cuts but try to plan your cuts so the final cut is still cutting, not smearing the surface!<br />
<br />
When facing or parting off, some skill is required to turn the cross-slide handwheel steadily to get a decent finish and to avoid shock-loading the tool tip. Increasing the spindle speed in one or more steps to keep up with the reducing diameter is advisable, but avoid speeds that cause resonances (resulting in chatter). When parting off, small through-hole parts may be caught on a thin rod chucked in the tailstock, and pre-positioned inside the work with its tip right up to the parting off position.<br />
<br />
==== Using the Steady Rests ====<br />
For the fixed steady rest, see Blondihacks' Lathe Skills #26 - How To Use a Steady Rest! [[#Youtube_Playlists_&_Videos|{below}]]<br />
<br />
Ours doesn't have ball bearing fingers, so a smooth surface on the work and adequate lubrication are essential. The thumbscrews can only tighten the fingers, so for small adjustments outwards you need to either slack off the clamping nuts or ease them slightly and use a drift against the back of the finger's slot. Once set, check the chuck still turns freely.<br />
<br />
The traveling steady rest needs to run on a machined surface, so at least for the first pass, must follow the tool, so its difficult to avoid using more compound slide overhang than is desirable. An initial surface should be cut next to the chuck or tailstock center before fitting the steady rest.<br />
<br />
Both are a PITA to fit - the fixed one has to have its clamping post inserted up through the bed, and the supplied spanner is useless near the headstock, and the travelling one's mounting holes on the saddle almost invariably need swarf picked out of them.<br />
<br />
==== Turning Between Centers ====<br />
<s>Using a MT3 to MT2 reducing sleeve, the MT2 dead center can be fitted in the spindle.</s> ''Currently the MT3 spindle taper is compromised.'' Alternatively, a soft center can be turned immediately before use in the three jaw chuck, but that must have its 60° point re-cut to concentric if the chuck is disturbed, and needs to be either large enough to bear on the chuck body, or must have a lip to bear on the end face of the jaws to take the axial thrust. Recutting the center is a PITA, as the compound angle must be set to 30° anticlockwise, then reset to a true 0° afterwards. Maybe a right-hand 30° end angle zero rake form tool is the answer, or use the carbide insert tool SSKCR0610H06 as a form tool with the toolpost rotated 15° anticlockwise.<br />
<br />
With the MT2 live center in the tailstock quill, this gives us a center either end of the work to hold it.<br />
<br />
We also need a drive dog similar to [https://littlemachineshop.com/products/product_view.php?ProductID=4473&category=1 this], and the corresponding drive post to bolt to the spindle nose. I have some 25mm bore thick wall iron pipe, which should do nicely. Lengths of the dog's straight tail and of the post TBD after I check how much the center protrudes. N.B. its recommended to tie the tail to the post to keep them in contact so they don't slam. ''Currently we will need to drive from the chuck jaws. Possibly use the exterior jaws with a short soft center gripped on the inside end and drive from the highest step.''<br />
<br />
=== Drilling ===<br />
Always start with a center drill so deflection of longer bits doesn't start the hole off-center. For larger bits (> 5 mm), first drill to the web size, then to final diameter. For a precision hole, drill slightly undersize and ream to final diameter. ''Supply your own reamers!''<br />
<br />
Caution: See note about the quill anti-rotation pin in section [[#Tailstock Quill|Tailstock Quill]] above.<br />
<br />
=== Boring ===<br />
Caution: As the spindle doesn't extend right through the headstock housing, if boring in a through hole, chips tend to fall out the back and tumble in the spindle bore till they fall into the change gears. To avoid this, one should plug the spindle bore with a wad of paper towel or rag and when cleaning up afterwards, use a rod to push it through towards the tailstock, with the chuck jaws (if fitted) wound clear of the spindle bore.<br />
<br />
A swivel bladed hole deburring tool (pale blue handle) can be found in the main room on the windowsill behind the drill press.<br />
<br />
A couple of boring jobs have been bodged with an awkwardly angled turning tool and achieving acceptable effective rake with enough clearance to reach deep enough into the hole has been problematic. I reviewed the tools we had and found none suitable for starting out in a 13mm bore, the max diameter we can (easily) drill. I therefore decided to buy a set of boring bars and make a holder for them. I had difficulty finding anything affordable under 10mm shank - the best low cost option was a [https://www.amazon.co.uk/dp/B07P5LGVBX set of nine 3/8" (9.525 mm) shank brazed carbide tipped boring bars], which would be close to the max capacity of the quick change boring bar holder - if we had one! Unfortunately this holder for our specific toolpost is difficult to find except in a toolpost bundle. Another annoyance is the variable tip height of the set, varying from 1.8 mm to 2.8 mm above the center of the shank.<br />
<br />
I therefore decided to make a boring bar holder of the [https://littlemachineshop.com/products/product_view.php?ProductID=1700 Littlemachineshop.com (USA) style] for use in the four way toolpost, as the additional rigidity will certainly help. Starting with a slightly over 50 mm length of 16 mm aluminium square bar and using the four jaw chuck , both ends were faced and an attempt was made to find its center and center drill it. It was then drilled out to ~9.8 mm after much drama due to blunt drills and drills that cut ~1mm oversize. Too big, but beggars cant be choosers as we didn't have a boring bar holder or a 3/8" reamer. Unfortunately the final hole ended up significantly off center. It was then chucked crossways and ~1 mm skimmed off its thickest side to gain clearance to allow it to be shimmed to height, then one side was slit lengthwise manually with a hacksaw.<br />
<br />
It was fitted to the for way toolpost and loaded with a booring bar, which clamped firmly. A 0.86 mm shim stack brought the tip of the largest boring bar almost spot on center height, with the difference easily accommodated by twisting the tool slightly. The three jaw chuck was then remounted, and a piece of iron pipe chucked for a test. It cuts well and leaves a decent surface finish.<br />
<br />
''The boring bar setup is a work in progress - talk to me before attempting to use them if you have a project that would benefit from boring..''<br />
<br />
ToDo: get something that can sharpen tools tipped with this grade of carbide - it needs some sort of diamond (or possibly CBN) wheel as green grit silicon carbide does little more than polish it. ''N.B. diamond wheels are rapidly eroded by grinding steel, so the supporting steel seat must be undercut with a regular grinding wheel before the diamond wheel can contact it.'' <br />
<br />
We'll also need 50 mm square sheet shims to fit under the toolpost to gain clearance in the toolpost above the tool or toolholder. A 2.4 mm shim would give us about the same above and below spindle center height, and we probably need a small selection of thinner ones.<br />
<br />
=== Thread Cutting ===<br />
The objective is to cut a thread that complies with the ISO metric thread profile. Our lathe is not currently equipped to cut non-metric threads, (with the exception of BA which have pitches based on metric threads of that era).<br />
<br />
[[File:ISO and UTS Thread Dimensions.svg|frame|center|Metric Thread Profile - from the geometry, H is ~86.6% of P]]<br />
<br />
Metric thread data - See 'Preferred Sizes' at: https://en.wikipedia.org/wiki/ISO_metric_screw_thread<br />
<br />
See "Mini Lathe User’s Guide" section '''Threading''' for general techniques *ONLY*, and above for change gears and threading dial setup.<br />
<br />
Amadeal specify the max. thread pitch as 2.5 mm. Any thread pitch greater than 1.5 nn requires the change gears to gear up. When gearing up it is desirable to distribute the ratio as evenly as possible over the two pairs of gears in the geartrain to avoid excessive tooth loading.<br />
<br />
==== External Threading ====<br />
Initially turn work to required Major Diameter, set up change gears and threading tool, touch off on the work, zero the top and cross slide dials, and do a 'scratch' pass to check the pitch. Back off the tool, return the carriage, and re-engage the half nuts on a valid dial line clear of the end of the thread then immediately stop the lathe, and hand turn the chuck till the tool tip is (hopefully) over the scratch to check the thread pickup. If all is good, return the carriage again, restart the lathe and start cutting your thread. <br />
<br />
Methods of doing so vary depending on the size of the thread and toughness of the metal, but straight-in plunge cutting is generally to be avoided as has the highest cutting forces, and does not reliably keep the carriage (and top-slide if set parallel to the work) loaded to avoid pitch errors due to backlash. <br />
<br />
If leaving the half-nuts engaged and reversing the lathe to return to the start of the thread for the next pass, its absolutely essential to back the tool out of the thread for the return pass as it will not follow the path of the cutting pass due to backlash in the geartrain, leadscrew mounts and half-nuts.<br />
<br />
==== Internal Threading ====<br />
''<nothing here yet>''<br />
<br />
== Cutting fluids ==<br />
=== Why bother? ===<br />
[https://youtu.be/mRuSYQ5Npek Watch this video] and contemplate what's actually happening to that thin ribbon of metal being removed. Most of the lathe's motor power is being turned into heat by internal friction in the chip being removed in the zone around the cutting edge, and surface friction at, and immediately behind the cutting edge, near-instantly heating the chip by up to several hundred degrees. Reducing the surface friction using a suitable cutting oil reduces the strain on the machine as a whole, and reduces workpiece and tool heating (and thus expansion) with consequent improvements in maximum usable feed and depth of cut, surface finish and accuracy. It also drastically increases the life of the cutting edge.<br />
<br />
=== Practicalities === <br />
We don't have a coolant system for the lathe and *really* don't want the maintenance hassles of using soluble cutting oil/coolant as if used infrequently its a PITA to keep recirculated high water content cutting fluids from going rancid and stinky, and they can also rust the ways, so even a total loss gravity feed system is problematic. Therefore if dry machining doesn't give a good enough finish, we tend to use oil applied topically, by hand to the work. <br />
<br />
* Hard brass is typically free-turning without oil, however some light oil for the final cut can improve surface finish, but with the disadvantage that it will increase loose chip buildup on the tool as hard brass typically forms short spalls or splinters rather than curly chips.<br />
<br />
* Many Aluminium alloys tend to be gummy, and Paraffin or other mineral spirits mixed with a little oil can help prevent the aluminum welding to the tool edge. WD40 will do at a pinch, but its messy to apply from a spray can.<br />
<br />
* Steel really needs *GOOD* cutting oil. Lard oil is the traditional choice for steel. If there are any objections to lard oil, we should bite the bullet and get some commercial dark high Sulphur cutting oil, but beware, many such oils use an additive package that includes lard oil.<br />
* Cast iron (except ductile) should be cut dry, as the carbon micro-inclusions self-lubricate it, and the carbide in the dust (primarily Cementite) are very abrasive, so tend to form a grinding compound if mixed with oil. <br />
<br />
I've sorted out an oil pot lid with a 1/2" brass collar soldered in to give a nice smooth sided hole, for ease of use and to minimize the risk of spills when using a brush to apply cutting oils, and got some dirt-cheap brushes. It fits Shippam's paste (and similar own-brand spread) jars and I've found several jars and ordinary lids to seal them for storage. Unfortunately it isn't the easiest to get this type of jars' lids back on square so they seal properly, and if you over-tighten them and there's a temperature change, they can be a total <expletive> to reopen. Using the rubberised handles of a large pair of pliers to grip the jar lid just above its rim is the best option, and avoids damaging the lids.<br />
<br />
''N.B. For the smaller brushes, the glue holding the bristles in is attacked by paraffin. To prevent loss of bristles, crimp the aluminium ferrule of each new brush of this type before use.''<br />
<br />
We have, in labelled jars:<br />
<br />
* Sulphurised Lard oil thinned with paraffin. Best choice for heavy cuts and threading in steel but stinky.<br />
* Lard oil thinned with paraffin. Good for steel and acceptable for softer copper alloys<br />
* Paraffin with a trace of light oil. Good for aluminium, and can help prevent squealing chatter on finish cuts in brass.<br />
<br />
I've also got some paraffin wax (in the form of a stubby candle), which can be applied lightly (under power) to brass and aluminium stock especially on the finish pass. It makes less mess than oil but unfortunately tends to build up on the tool tip, making it difficult to 'work by eye' without frequent pauses to clean the tool tip.<br />
<br />
We've also got a tin of [https://www.rocol.com/products/rtd-compound Rocol RTD cutting compound], which is a thick paste. Its highly recommended for drilling and tapping steel (in the drill press or by hand), but as a paste, is less useful for general lathe work unless thinned to a fluid consistency, e.g. with paraffin or white spirits. OTOH its certainly worth trying for high speed facing steel as it is less likely to get flung off.<br />
<br />
== Cleaning and Maintenance ==<br />
Swarf is a significant cut hazard to the operator, especially stringy swarf from cutting steel. Never touch it bare-handed - always use a tool e.g. a brush, or a hook, or needle nose pliers for grabbing long swarf.<br />
<br />
* After use, brush all swarf off the toolholder, compound and cross slide etc. ways and leadscrew. Ian B has blocked off the opening at the headstock end of the rear splashguard (to try to keep swarf out of the motor), so one must sweep the swarf towards the open tailstock end and catch it in a dustpan or similar. Preferably, also thoroughly clean out the chip tray under the lathe, but at least sweep out visible swarf.<br />
* Wipe up any cutting fluid residue and re-lubricate affected sliding surfaces with way oil.<br />
* Do not solvent clean the chuck guard, as it will make the plastic brittle, or even craze it. Water with a little detergent is permissible for cleaning it, with the guard totally removed from the lathe.<br />
<br />
Before engaging the half-nuts for power feed/threading, check the leadscrew is clean! ''Best cleaned under power, with a toothbrush.'' <br />
<br />
'''Caution:''' The traverse gears behind the carriage handwheel are in an open-backed housing and tend to become packed with swarf! Swarf buildup here will result in jerky carriage movement. Clean out as much as you can with a toothbrush ...<br />
<br />
===Lack of lubrication and/or swarf or dirt build-up can be disastrous===<br />
* If using the change gears/power feed, lack of lubrication of the B-C stub shaft center pin or either leadscrew end bearing can result in seizure and immediate destruction of one or more gears in the gear train or worse. <br />
* Small pieces of swarf can get between the saddle and ways, or into the slides degrading accuracy, possibly permanently if hard swarf scores them, or jamming them. The carriage handwheel gears behind the apron are notorious for accumulating swarf, and swarf buildup on the leadscrew can prevent the half-nuts engaging properly, resulting in scrapped work, and possibly stripped half-nuts. <br />
* Metal swarf can get into the motor (''though Ian B has modified the rear chip catcher to reduce the risk)'' or into the control box via the leadscrew, and short-circuit stuff. At best it will blow the fuse and need a strip-down to clean it out, at worst it may require a replacement [https://www.amadeal.co.uk/acatalog/Speed-Control-Circuit-Board--12amp-AMA_SP_CJ18_SCB12.html#SID=12 speed controller] ''(currently £96)'' and/or [https://www.amadeal.co.uk/acatalog/550W-motor-for-CJ18A-Mini-Lathe-467.html#SID=240 motor] ''(currently £105)'' and possibly other electrical parts. We should probably fit a [https://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C3-Mini-Lathe-Spares/C3-256-Leadscrew-Grommet-Dustproof-Cover C3-256 Leadscrew Grommet] to keep swarf out of the control box, as it tends to drop onto the 'Filter' board which is mounted horizontally, below the leadscrew.<br />
* Grit from grinding, sanding etc. forms a grinding paste with the way oil, and will rapidly wear out the ways, saddle and slides. Keep grit off at all costs e.g. by covering the ways and slides during grinding/sanding operations, and if there's any chance grit has gotten where it shouldn't, clean and re-lubricate *BEFORE* moving the carriage or slides, then move the carriage and slides, wipe down where they were with a clean paper towel and check there's no remaining traces of dirt other than clean way oil on the paper towel. If it doesn't come clean when you re-lubricate and move it again, a full strip down may be required to solvent clean and relubricate the precision sliding surfaces.<br />
* Although a metalworking lathe *can* be used to turn hardwood, wood dust and small chips are extremely pernicious, as they get everywhere, even clinging to clean surfaces, are abrasive due to their silica content, and are hygroscopic, promoting rust. An even more thorough clean-up than after using abrasives is needed, immediately afterwards. Oily wood dust and fine wood chips in significant quantities are a fire hazard, even in the trash bin.<br />
<br />
===Lubrication===<br />
See section: "Lubrication" in LittleMachineShop.com "Mini Lathe User’s Guide" [[Ian_M's_Lathe_Notes#Manuals|(below)]]. As we usually only open two nights a week, in the table on page 16, Daily lubrication becomes Weekly and Weekly becomes Monthly.<br />
<br />
===General Maintenance===<br />
* The grubscrews holding the cross-slide and compound slide dials tend to loosen due to vibration and use of the dials. Keep them snugged up, but not so tight the dials cant be set without an Allen key.<br />
<br />
* The screws holding the cross-slide nut tend to work loose due to vibration. Crank the handle to and fro through the backlash and visually check there is no movement of the screw heads in their holes. If there is, see the [[#Excessive_cross-slide_backlash|notes below]].<br />
<br />
===Removing the Carriage===<br />
Its possible to remove the carriage from the bed for cleaning etc. without dismantling it. The only stop to its motion is the righthand leadscrew bearing.<br />
<br />
Start by removing the tailstock. Crank the carriage to the tailstock end then remove the leadscrew bearing (two screws and a nyloc nut on the leadscrew end). With the half-nuts open, hold the leadscrew centered in them and crank the carriage off the end of its rack, then slide it off the end of the bed.<br />
<br />
Refitting is the reverse of removal, except (if its gibs are correctly adjusted) the carriage will be very tight on the end of the bed ways so may be difficult to work onto the ways without a stack of blocks of wood or similar to support it at exactly the right height. The righthand leadscrew bearing must be refitted with the carriage as close as possible to it and the half-nuts firmly closed to support the leadscrew at the correct height to hold it in alignment while the screws are being tightened. The nyloc nut controls leadscrew end-play. Fully tighten it then back it off slightly till the leadscrew turns freely with its change gear removed.<br />
<br />
If the Apron has been off, refit it with the screws no more than lightly finger tight and only finally tighten them after checking lead screw engagement at both ends of the carriage travel and that the rack and pinion operates smoothly over the full travel.<br />
<br />
== Issues and Annoyances ==<br />
As of September 2023 - mostly resolved, apart from the spindle bearings and runout, the lathe is in better condition than it has been for a number of years.<br />
<br />
===Four Jaw Chuck has two jaws too tight===<br />
Fixed 27/10/2023: The grooves in the opposite sides of the jaws that run in the chuck slots were slightly out of true, and the rails either side of the slots were slightly too thick towards the center. Due to the difficulty of seeing the high spots, after cleaning up and deburring the jaws didn't do enough to ease them, I decided to grind the top of the rails where they were binding. Several repetitions of spotting, grinding then diamond filing the high spots has eased them enough. I cleaned everything, greased the jaw slides and screws, and refitted the studs so the chuck is now fit for service. <s>Two of the chuck jaws are tight in their slots, making precise adjustment difficult due to lack of 'feel'. Moving the jaws round the slots shows the problem follows the jaw not the slot, and stoning various edges hasn't helped so it seems that the affected jaws are slightly oversize. Need Engineer's spotting blue to determine which of the sliding surfaces is binding, so we can see what needs scraping/stoning/grinding to fix them</s><br />
<br />
''N.B. Don't move the jaws to a different slot - the formerly tight jaws *must* stay in the slots furthest from the makers mark.''<br />
<br />
===Excessive Runout===<br />
Mostly fixed 24/10/2022: I ground the chuck seating surface of the spindle nose (outside lip) to under half a thou runout. This also cleaned up several burrs. It would be possible to do better, but that would need good spindle bearings, and a more rigid toolpost grinder mount.<br />
<br />
Our spindle nose was damaged years ago by a person with little mechanical aptitude (who shall remain nameless) beating it up with a hammer mushrooming the spindle nose. We are getting several thousandths runout at the end of the MT3 bore, a MT3 to MT2 reducer sleeve in it runs visibly out of true, as does the spindle nose flange. When you put a chuck on it, the runout is magnified by the distance from the spindle nose. Ideally we would replace the spindle when we change the bearings but its £52 [https://www.amadeal.co.uk/acatalog/4-Spindle-Upgrade-Real-Bull-Mini-lathe-CJ18-series-AMA_SP_CJ18_003RB.html#SID=9 from Amadeal] and money is tight. It may well require more work after the bearing upgrade. Once good bearings are in, if we can borrow a decent MT3 arbour as a reference, we should consider skimming the bore.<br />
<br />
===Spindle bearings===<br />
* The spindle bearings appear to be close to worn out. They are notably noisy when running, and there appears to be more slop in the spindle than is desirable. We have some ideas for possible replacement/upgrade, but it requires a major teardown.<br />
<br />
: The original bearings are allegedly 6206-2RS or 6206-ZZ deep groove ball bearings - 2RS codes rubber seals both sides and ZZ codes metal shields. Although the deep groove gives reasonable ability to withstand axial loads, the bearing balls point contact means they are vulnerable to [https://en.wikipedia.org/wiki/Brinelling brinelling] due to shock loading. The jammed on three jaw chuck didn't help this, as before we skimmed the spindle nose lip, it had to be driven off using a bar through the spindle bore, shock loading the bearings every time. Also even a minor 'crash' could have brinelled them due to eccentric shock loading, and the lathe has previously been crashed badly enough to need drive gear replacement. There are also issues with the 'approved' method of spindle and bearing removal from the headstock brinelling them, even if you don't abuse the spindle nose with a hammer!<br />
<br />
: A possible replacement is 30206 tapered roller bearings. The new bearings are slightly thicker so the plastic spindle spacer (15) needs to be machined to length to get the 45 tooth spur gear that drives the change gears laterally aligned with the tumbler gears. If a temporary replacement (3D printed?) is fitted, the lathe can be run (without power feed capability) so this can be done on the lathe after fitting the new bearings. As tapered roller bearings have line contact, they are significantly more resistant to brinelling.<br />
<br />
: ''See [[Talk:Ian_M%27s_Lathe_Notes]] for notes, links etc. for this upgrade.''<br />
<br />
===Motor stuttering===<br />
* Fixed 21/09/2023: The motor was running very erratically and it was very difficult to set a speed. Several loose connections were found in the control box, mostly loose female spades to the motor controller board, but also a dry jointed braking resistor on the 'Filter' board, and an inhibit wire completely off its terminal on the forward/reverse switch, making intermittent contact. After tightening and/or remaking all affected connections, it was much improved but still not right below 300 RPM. The remaining issues were due to poor wiper contact in the speed control pot, and stripping it, cleaning the track and contact ring and re-tensioning the contacts resulted in the motor now running smoothly over the full speed range. The speed is slow to settle, and while part of that is probably the lag in the digital tach, I suspect that the KBIC motor speed controller isn't properly tuned as it was (allegedly) previously replaced.<br />
<br />
===Drive belt slipping===<br />
* Fixed 28/9/2022: During testing the motor after the above issue, it was noted that the chuck could be stalled, slipping the drive belt, with not much torque. The drive belt was determined to be loose and a bit worn, but still in acceptable condition. <br />
<br />
: Access for servicing the belt requires removing the control box ''(2 spades to ZVR switch disconnect the supply, speed sensor and motor simply unplug from the 'filter board')'', the motor cover, chuck guard switch assembly + wiring cover, the change gear 'A' (drive) shaft carrier assembly, and the tumbler gear assembly. See https://youtu.be/EkxlIz01BdA for disassembly/reassembly, though on our lathe, the speed encoder ring on the spindle prevents the belt cover from being fully removed without disturbing the spindle nuts. There is enough room to work with it loose, but still trapped by the encoder ring. Also, unlike the video, if the 'jack' screws under the headstock are correctly adjusted, and the studs aren't excessively bent, there is no need to make custom studs. <br />
<br />
: It turns out that our lathe was missing the M6 hex headed jack screws that press the motor down to resist the belt tension, and the motor had cocked out of position at a severe angle. I know Ian B had had considerable trouble adjusting it after the motor fault back in October 2022, and I believe it had been getting slowly worse ever since. The jack screws were probably mistaken for headstock fixing bolts during disassembly after the crash that resulted in the metal Hi/Lo gears being fitted, then lost. The penny washers on the studs had dished, so I turned them over and backed them up with smaller washers and switched to nyloc nuts so they cant back off due to vibration. N.B. there is a packing washer on the motor side on one of the studs, presumably so the shaft is true to the ways. Adjusting the motor is awkward to say the least. One has to slack the stud nuts off a lot, pry under its rear end to lift it enough to be parallel to the ways, snug the stud nuts, check alignment, then set the jack screws and their lock nuts to hold it there, and finally tighten the stud nuts. <br />
<br />
: Tension: According to Sieg, it should be possible to twist the belt 90° mid span with a light finger grip. Other sources say 1/32" - 3/32" deflection mid span with light finger pressure.<br />
<br />
===Speed display blanking===<br />
* The speed display has been intermittent, blanking and flashing 8888 and 0 at certain speeds for as long as I have been using the lathe. Finally on 18/07/2022 it failed completely, with no display. I removed the display module and bench tested it - the pins are labelled 5V GND PL PE, PE is frame ground and PL is a TTL level pulse from the speed sensor - confirming that it was in good working order. My suspicions then turned to its power supply on the 'Filter' board. With both the sensor and display unplugged, the 5V rail was found to have a only a couple of volts, but the unreg DC was 17V and stable. Replacing the 78L05 5V regulator restored the 5V rail and normal operation.<br />
<br />
: ''I conclude its been failing for a while with high load current due to speeds with more lit segments causing it to drop out, resetting the speed display, causing it to blank, lowering the current enough for the regulator to recover, then the display MCU lamp tests (8888) then re-acquires the speed, repeating ad-nauseum till the speed is changed. I don't like the design as the high input voltage results in excessive dissipation.'' <br />
<br />
: ''ToDo: Bench test display to measure its worst case current consumption, then fit an appropriate dropper resistor to reduce the 78L05 dissipation.''<br />
<br />
===Quill spinning when drilling===<br />
* The quill was tending to spin while drilling because its anti-rotation pin (a M5 dog tip setscrew) was sheered. I've removed the debris, aligned the scale with the top of the tailstock and fitted a longer M5 dog-tip setscrew to replace it, with a nut to lock it at the correct height. N.B. the pin isn't that 'meaty' so if using big drills in tough metals, to prevent shearing it, it should be backed out so the quill can be turned by hand and unwanted rotation controlled by being quick with the quill lock if it starts to spin, or even using a close fitting rod in one of the chuck key holes with plastic tube over it to protect the ways. <br />
: ''If the screw sheers again, the quill will need to be removed and the tailstock taken off the lathe so the sheered tip can be shaken out, and if the setscrew is difficult to remove it probably means the threads are mangled where it sheered. Try driving it right through with the quill out.''<br />
<br />
===Sloppy quick change toolpost locking mechanism===<br />
* Once the dovetail clamp screw was slackened, there was nothing preventing the dovetail twisting or cocking significantly, and friction with the toolholder made it tend to do so, making toolholder insertion and removal more difficult unless the clamping screw was backed off excessively. I added a compression spring around the clamp screw inside the toolpost to push the dovetail outwards so it mostly retains alignment when open, allowing toolholders to slide on or off cleanly with far less screw slackening.<br />
<br />
===Leadscrew rubbing===<br />
* The leadscrew shaft is rubbing on the insulating separator inside the control box. Unfortunately the corner of the relay on the Filter Control Board (#160) doesn't allow enough clearance. Although the friction isn't much of a problem at high reduction ratios, e.g. 16:1 power feed, it increases the stress on the change gear train, and may be problematic when threading at feeds above 1:1. ''Possibly pack out the control box mountings by a couple of mm.'' <br />
<br />
===High/Low lever backwards!===<br />
* The high-low drive gear selector behind the headstock is incorrectly labelled and differs from the manual: low gear (which we normally use) is with the lever towards the tailstock. ''I suspect that the gears in the headstock were refitted the wrong way round when it was upgraded to metal gears.''<br />
<br />
: ''ToDo: Get it reassembled the right way round during the spindle bearing upgrade!''<br />
<br />
===Carriage lock fouls top slide===<br />
* The T handscrew has been replaced with a M5 hex headed bolt, to permit access when the top slide is over it. An 1/4" drive 8mm socket is usually left on it, but needs to be removed when the full cross slide travel is needed. The small (4 jaw) chuck key is near enough 1/4" to use for it. If you need to (un)lock it while the compound is over it, you'll need an 8mm spanner. ''The [https://www.amadeal.co.uk/acatalog/Mini-Lathe-Carriage-Lock-463.html Amadeal lock screw] is in the spares tin as it was too high and fouled the compound slide.''<br />
<br />
===Tailstock locking lever loose===<br />
[[File:Tailstock.jpg|thumb|Inside the tailstock - See full image for key to screws]]<br />
* Diagnosed and fixed 10/1/2023 - In the base of the upper section of the tailstock, there are two dog tip set screws that engage with locating grooves in the counter-rotating shafts carrying the eccentric locking cams. They'd backed off, probably due to vibration. They need to be tightened till they bottom out in the groove, making sure they are '''in''' the groove, backed off half a turn so the shafts can turn easily, and locked in place. There's no facility to do so, so reassemble with weak threadlocker. Unfortunately to get to them you have to remove the tailstock base slide, which is held on by the pressure of four adjusting grub screws, which all need backing off, and one socket headed bolt from underneath so full tailstock realignment is required after reassembly, which even for a rough alignment is tedious.<br />
: <s>The tailstock locking lever is loose and can be pulled out on its axis. It works OK when fully pushed home but needs investigating. ''I tightened the grub screw as the lever was coming off its shaft, but the whole shaft pushes/pulls in and out. It works OK fully pushed in, but it seems something that is meant to retain it has failed inside the tailstock base.</s><br />
<br />
===Gear alignment issues===<br />
* Change gear alignment is poor. I've currently got a gapped washer (to clear the key) packing out the A shaft so the gears line up, but this reduces the key's engagement so is problematic due to the high loading if the gears are set up for coarser threads. <s>Also I need to turn down some penny washers to slightly less than the root diameter of the metal 20T pinions, as gear retaining washers.</s> ''The gear retaining washers for A gear and B-C stub shaft are now done, turned down to slightly under 16 mm dia. Spares in the change gear tin. ToDo: The D (leadscrew) washer requires a larger center hole, so make two more with that hole.'' <br />
<br />
===Saddle gibs loose===<br />
* Fixed 11/04/2023: I took the apron off for access (and to clean the carriage handwheel gears), and found the front sheer plate screws were completely loose. I've snugged them up some and set the opposing grub screws and got a lot of the slop out. I've re-checked the front ones, and taken up the slop in the rear ones - Unfortunately it wasn't possible to get carriage movement to have an even 'feel' over its whole travel, and its noticeably tighter near the tailstock. If light hand pressure on the side of the unlocked carriage can cause movement (with the half-nuts open), its time to readjust them again, though it should be possible to move the carriage with a firm push. <s>The saddle gibs (actually the sheer plates) were too loose, to the point that engaging a slightly stiff threading dial could cause it to self-feed, an obvious crash hazard if working near the chuck or a step in the work.</s><br />
<br />
''N.B. the lefthand front opposing grubscrew is short, (fully recessed) and unlike the others does *NOT* have a locking nut as it must clear the traverse pinion. A wrap of PTFE tape provides enough friction to keep it in place, though possibly a bit of nylon fishing line down its hole would be better.''<br />
<br />
===Excessive cross-slide backlash===<br />
* ''Mostly Fixed <s>11/10/2022</s> again 07/11/2023:'' The cross-slide screw had excessive backlash (nearly three turns), possibly due to end float, which increases the risk of loosing track of the cut depth during threading operations. If you ended up off by a turn too far in, a crash was the most likely outcome.* 02/11/2023: The backlash is back up to one turn. I suspect the cross-slide screw nut mountings are working loose again.<br />
<br />
: So it turned out that the reason the cross-slide had nearly 3mm of backlash wasn't end float, it was loose cross-slide screw nut mountings. The nut has two socket headed cap screws pulling up, one either end, accessible from the top of the cross-slide, which control the tilt of the nut to take up backlash in the nut, and an opposing grub screw pressing down on the center of the nut to make it longitudinally rigid. I gambled the cap screws weren't too far out and snugged up the grub screw, and that immediately took out over 95% of the backlash which is now down to 10 divisions or so, or 0.25 mm. Shimming the cross-slide screw collar should take out some of what's left and careful adjustment of the nut tilt should get that down to under 0.1mm.<br />
<br />
: 07/11/2023: When the problem recurred I investigated further . It is difficult to get the cross-slide nut aligned correctly as it must be at the same height as the screw which is constrained by the bearing surfaces in the bracket. With the cross-slide almost at the front limit of its travel, I removed the screw and set the nut as level as possible and visually centered in the bore, then re-fitted the bracket and screw, then adjusted the tilt till it turned freely through the backlash. I then tilted it up at the front till some drag was felt to minimise the backlash and tightened the screws to lock it in place balancing them to maintain the same feel as I tightened them. The result was 7 divisions of backlash, acceptable but not great. During normal turning operations, the load on the nut is tension on the front screw and pressure on the grubscrew, so if it slackens again due to vibration from chatter, odds are it will be the rear screw that's loosened. <br />
<br />
* Further reduction of backlash: https://youtu.be/Wu_tI29JL2Y?t=163 <br />
: Brass tinned with Pb-free solder to form a white metal bearing surface should work at least as well as the bronze used in the video. The shim washer needs to be 10 mm ID and ~14 mm OD. It isn't necessary to remove the lead screw from the cross slide, as the washer can be fitted in-situ with only the bracket removed. Its also possible to closely estimate the required washer thickness from the backlash - note the number of dial divisions of backlash, then strip down the dial and bracket and with the gibs tight enough to keep the cross-slide from moving, push and pull the screw to assess its end float. A dial indicator mounted on the cross slide probing the screw flange will give you the total end float. Subtract the end float from the backlash, than take off another thou (0.025 mm) for running clearance to get the washer thickness (assuming it seats fully in the recess). If after fitting it, snugging up the bracket screws makes the screw too stiff to turn, the washer is too thick - either make another one or try to lap it down.<br />
: TLDR: measure flange on cross-slide screw and depth of recess in cross-slide bracket (behind dial) and machine a shim washer to take up nearly all the difference.<br />
<br />
===3 Jaw chuck didn't mount properly===<br />
* Fixed 7/4/2023 by grinding the spindle nose lip. The three jaw chuck can now be installed and removed by hand with no hammering. A test bar in it now has only 2 thou runout (TIR) at the chuck.<br />
: <s>The three jaw chuck and the faceplate aren't seating properly on the spindle nose. Its too tight on the register diameter of the lip. This results in grossly excessive runout, and also makes this chuck and the faceplate a PITA to fit or remove.</s><br />
: ''The spindle nose had been abused with a hammer (before my time) which mushroomed it and may have brinelled its bearings. See '''Excessive Runout''' and '''Spindle bearings''' above.''<br />
<br />
== Manuals, Books and other resources ==<br />
=== Manuals ===<br />
The [https://wiki.richmondmakerlabs.uk/images/a/a3/Lathe_InductionNotes.pdf RML CJ18A Mini-Lathe Induction Notes]. Your mandatory Lathe Induction will cover most of this but its good to be able to refer back to it.<br />
<br />
Official [https://web.archive.org/web/20170618065028/http://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf Amadeal CJ18A Manual], or paper copy (less complete) kept on shelf above lathe.<br />
<br />
The [https://www.chesterhobbystore.com/wp-content/uploads/2022/11/Conquest-Super-Lathe.pdf Conquest Super Lathe manual] is considerably better than the Amadeal manual and is for a near-identical machine.<br />
<br />
The [https://littlemachineshop.com/images/gallery/info/minilatheusersguide.pdf Mini Lathe User’s Guide] from LittleMachineShop.com is even more comprehensive, going into its usage in some detail, with a proper TOC, and covers both US and Metric versions of Realbull Mini-lathes. ''The only fly in the ointment is the threading section assumes a US lead screw so change gear selections and threading dial divisions will not be correct for our lathe.''<br />
<br />
[https://www.arceurotrade.co.uk/machineguides/C3-Mini-Lathe-Dismantling-and-Reassembly-Guide.pdf Sieg C3 Mini-lathe Dismantling and Reassembly Guide] "A picture story book to help you dismantle and reassemble your Sieg C3 Mini-Lathe" ''It is similar enough to ours to serve as a maintenance guide, except for the electronics, spindle drive and other headstock innards.<br />
<br />
The motor controller is a clone of a [https://acim.nidec.com/drives/kbelectronics/-/media/kbelectronics/documents/dc-drives/manuals/kbic_manual.ashx?la=en KBIC® SCR DC Motor Speed Control]<br />
<br />
=== Books ===<br />
'''Metal Turning on the Lathe''', by David A Clark, Crowood Metalworking Guides, ISBN-13: 978-1847975232 [https://www.amazon.co.uk/gp/product/B00E78RKIG Kindle Edition (£8.99)]. ''A 'free' epub can be googled for, *NOT* linked here due to dubious legality.''<br />
<br />
'''[https://archive.org/details/03screwcuttinginthelathe Screwcutting In The Lathe]''', by Martin Cleeve (a pen-name of Kenneth C Hart), Workshop Practice series #3, ISBN-13: 9780852428382<br />
<br />
'''[https://archive.org/details/15workholdinginthelathe Workholding in the Lathe]''', by 'Tubal Cain' (a pen-name of Tom Walsh), Workshop Practice series #15, Argus Books, ISBN-10: 0852429088<br />
<br />
'''[https://archive.org/details/20metalworkandmachininghintsandtips Metalwork and Machining Hints and Tips]''', by Ian Bradley, Workshop Practice series #20, ISBN-13: 9780852429471<br />
<br />
'''[https://archive.org/details/38toolandcuttersharpening Tool and Cutter Sharpening]''', by Harold Hall, Workshop Practice series #38, ISBN-13: 9781854862419<br />
<br />
'''[https://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpaperT204.pdf Cutting Fluids]''', by EC Bingham, NIST Tech. Paper No. 204, 1921<br />
<br />
=== WWW resources ===<br />
==== Mini-lathe Specific ====<br />
There's a *LOT* of mini-lathe info online. Notable sites include:<br />
* http://www.mini-lathe.com/ - A major Realbull/Sieg mini-lathe resource.<br />
* http://mikesworkshop.weebly.com/lathe-modifications.html - many mods including carriage DRO autostop, and variable speed leadscrew motor drive, cross-slide motor drive, etc. He also has a page with a bunch of accessories, toolholders etc. - http://mikesworkshop.weebly.com/lathe-accessories-and-tooling.html<br />
* http://andysmachines.weebly.com/variable-speed-controls.html - Scroll down to the 'UPDATE' section for the schematic of a very similar SCR speed control board. It also has the schematic for an earlier version of the Auxiliary Control Board (aka: 'Filter' board).<br />
<br />
==== Forums ====<br />
''with publicly accessible archives''<br />
* https://groups.io/g/7x12MiniLathe - Mini-lathe specific, active<br />
* https://www.hobby-machinist.com/forums/mini-lathe-mini-mill-information.220/ - active<br />
==== Youtube Playlists & Videos ====<br />
* Blondihacks: [https://www.youtube.com/playlist?list=PLY67-4BrEae9Ad91LPRIhcLJM9fO-HJyN Lathe Skills] (playlist) - "This is an educational series to help you learn to use your metal lathe. Watch them in order for best results! Satisfaction not guaranteed, especially if you're a cranky sort of person."<br />
* Frank Hoose (Minilathe.com) has a couple of relevant Youtube playlists:<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn7ON0jGM5UbM-KZDT56MOIp Mini Lathe Operations]<br />
** [https://www.youtube.com/playlist?list=PLLPP9zpsEfn4nGRZaVq3wTOlvZNOmdAZ2 Mini Lathe Overview]<br />
<br />
==== General Machining ====<br />
* https://www.machiningdoctor.com/ - "THE #1 MACHINING TECHNICAL HUB"<br />
<br />
==Projects==<br />
[[File:VESA mount.jpg|thumb|Machined VESA mounting plate (left) and plate from Dell monitor stand it must match (right). The translucent washer shows the size of the original center hole.]]<br />
* My first faceplate project was boring out the center hole in a VESA mounting plate to adapt it to fit onto a surplus Dell 1708FP monitor stand. The part was centered using the tailstock dead center engaging with its original center hole. I clamped the part with studs and penny washers on the driving side of two opposite corners, with cap screws in the next slot round to trap the corners under the clamping washers, then withdrew the tailstock and dead center. After machining out the bore, I used the tip of the tool, rotating the chuck by hand, to scribe a circle for laying out the bolt holes. I finished off laying out and drilling the bolt and locating holes by hand at home, fitted it to the stand, and mounted the 2nd hand LG 24" widescreen monitor.<br />
<br />
* Another ultimately unsuccessful project was fly cutting aluminum flat bar to thickness to make custom shims for the set of carbide insert tools, for the four way toolpost. The 8 mm shank tools need ~2.5 mm shim stacks, and the 6 mm shank tools need ~4.5 mm shim stacks. Ideally I'd machine single shims, but the only stock I've got handy cleans up to only 3.2mm, and some fine shimming may be needed to fine-tune the tool height.<br />
<br />
: After sorting out the clamps so they were no longer twisting the aluminum flat bar stock, and switching to the short 45° turning SCMT06204 insert tool in the four way toolpost, to improve rigidity and get a well controlled tip radius, the finish was much improved. I'm still having problems getting an even thickness and am getting approx. 0.05mm variation, I suspect due to the aluminium bar stock distorting due to internal stresses as its surface is cut away. ''ToDo: try supergluing the stock to the faceplate before clamping to further reduce chatter and stop the warping.''<br />
: Looking back on this project a year later, its fairly obvious that the thickness variation was probably due to faceplate surface runout due to the damaged spindle nose.<br />
<br />
* Raphael has been working on a steel rocket nozzle with some assistance from myself. We have set up the rough cut chunk of ~ 50mm steel bar, faced both ends (to 50mm length) and turned the OD to 49mm to clean it up. Its going to need through drilling, probably some boring, and quite a bit of detail work on the OD. It will then need to be transferred to a jig in the drill press vice to allow a pattern of angled traverse holes to be drilled with acceptable accuracy.</div>IanM