This software and instructions are provided as is, without warranty of any kind. This is a hobby project. Using this might damage your equipment, cause injury or death. Use at your own risk.
Any electronic lead screw requires connecting an encoder to the lathe spindle and motor to the leadscrew. This page provides some general guidance but every lathe is different, start a new discussion if you have questions.
Tested with the following 600 steps encoder. They are available on eBay/AliExpress as "optical rotary encoder".
Attached using 2x M4 bolts to the side of the headstock. Using an M4 set screw is optional.
Alternative encoder base allowing for a thicker cable: https://www.thingiverse.com/thing:5156081
Check the distance between the spindle gear and the lathe housing: for the provided conical gear to fit, it has to be 23mm.
Encoder gear should fit loosely to the spindle allowing for it to move ~1 degree back and forth when the spindle is idle - it reduces the noise and forces applied to the encoder.
For spindles with 56 teeth, try 56 teeth gear model by kingjamez.
Cheap drivers like TB6600 are not recommended, they are very rough and noisy.
For H1 or H2 controllers it's suggested to buy the stepper that supports 200 steps mode. Microstepping will lower maximum usable rpm 2x for each microstep increase. I can recommend STEPPERONLINE steppers for good price and performance and their drivers usually support 200 step mode.
For H4 controller it's suggested to use integrated closed loop motors like these. They don't support 200 steps mode but H4 can easily run them at 800 steps per revolution. They don't need a separate driver, don't heat up and work quetly. They do take a but more space than open-loop steppers though.
48V power supply is used on NEMA 23 for maximum power (check your driver max voltage) but 24V might also work for light turning. Closed loop motors require less current than open loop ones since they adjust to the load. For a lathe like WM210 with NEMA 23 and NEMA 17, 4A power supply would be sufficient.
Dimensions of the lead screw front bearing housing for the provided 3D-printed part to fit: 28mm outside diameter, 12mm wide.
Stepper should rest on e.g. a piece of rubber when attached to the lathe - provided 3D printed part is only held by friction and is not designed to hold the full weight of the stepper long term.
A rock-solid but more expensive (35€) option is to order a 10mm steel laser cut out stepper mount: https://imgur.com/a/exO5Atl
It's also possible to cut out the stepper mount manually from plywood: https://imgur.com/a/CSmeSm2 (PDF)
Alternative stepper mount with a pinch bolt: https://www.thingiverse.com/thing:5156087
See https://www.thingiverse.com/thing:6058899 - I use it with a 60mm open-loop NEMA 17 motor. It fits most desktop lathes like WM210.
It's good to insert a thin metal shim in the back to thermally sink the motor in to the lathe apron. Thickness of the shim can vary.
When connecting the gears, make sure to leave ~0.5mm space between them for optimal threading. This can be achieved e.g. by temporarily placing a piece of paper between them. Add grease and spread it between the gear teeth, remove the excess.
This gear is designed to fit the NEMA 23 shaft (10mm diameter / 9.5mm narrow dimension) without any set screws. Gear is 10mm wide, entire part is 20mm wide.
Using this gear can be very noisy on certain RPMs.
If you have 2 metal gears that add up to 100 tooth together (e.g. 2x50 tooth gears) that came with the lathe, it's possible to simply use one of them on the leadscrew and one on the stepper with the help of the adapter above. It can be somewhat noisy on certain RPMs but otherwise works well.
This is the best stepper to leadscrew connection method that I tried so far but it requires printing 2 parts above and buying a 180mm HTD 5M belt which is not expensive (2-10€) but can be hard to find.
This is the quietest option that also doesn't need greasing. 2 pulleys and a belt fit tight on the normal stepper mount shown above without a need for a tensioner.
16T-5M pulleys with various inner bore diameters are also available on AliExpress for 5-6€ each.