If you put 12 volt dc motor into ebay you will get many hits. Most of the 35 mm diameter motors will have sufficient power to drive the leadscrew of a small minilathe. I have fitted a motorised leadscrew to my lathe, see:

http://mikesworkshop.weebly.com/leadscrew-motor.html

http://mikesworkshop.weebly.com/new-threading-banjo.html

http://mikesworkshop.weebly.com/control-circuits.html

Mike

Rather than measuring the torque required and using that (doubled) to choose a motor, I suggest you look at a reduction by belt drive. This can be round or toothed, and it will allow you to select a motor which has less torque and more speed (ie most motors) than you actually need. A five times speed reduction will give you five times the motor torque, and one fifth of the speed. The drive etc needs to have a fail-safe built in, perhaps relying on a round belt will do, to avoid any possibility of driving the saddle through the headstock. Microswitches are helpful here, and perhaps a fuse to blow just below the stalled current to avoid burn out.

I have done this on the leadscrew (effectively) of a mill, and if you need details of motor etc I will pull it down off the shelf and peer at it for you. Just say.

Regards, tim

This is what I did on my milling machine using a BLDC geared motor

Bob

One way to think about it is that a lathe normally has only one or two power feed speeds, so perhaps you don't need the range that you'd like on a mill. Perhaps start with the normal max speed on the lathe auto-act, bear in mind that the slowest one is too fast for some things, so go from perhaps 1/3 of the slowest to 2x the fastest, and you should have something a lot more versatile than the mechanical feed.

That speed controller only gives a 10:1 range of PWM ratios so may be a bit limited depending on the above calculation.

The motor looks a bit tiddley to me, I'd go for something beefier. Also I think 2A is light for the PSU – just been reading Mike Stratton's article on power drawbar in the latest MEW, he got a 25 amp 12 V PSU for £17 off eBay. It's always useful to have lots of amps round the workshop.

Final point, some speed controllers don't like having their outputs open circuited when you throw a reversing switch when the motor is running, a centre-off switch might be useful so the motor can stop before the reverse volts are applied.

Edited By John Haine on 09/03/2016 17:23:24

The 2 normal feeds on the lathe always relate to speed John – that's the catch. They are per rev what ever the speed the lathe is running at.

It's a natural for a geared down stepper really as the revs are so slow but I really don't fancy writing any software and if some one did it would probably have a display and scrolling buttons etc.

John

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I think the article he is referring to is in MEW #240, April 2016. Building an electronic leadscrew – Chris Gabel converts his lathe using the electronics kit from Automation Artisans.

Clive

Check out YouTube – Clough42 – developing an electronic lead screw