hi;
sometime ago I cnc my little lathe using the smooth stepper, I added the index sensor in the back , and seem to work ok, well , the threading was done at 2000rpm.. I used a piece of 1/2 inch brass
sticking out 40 mm from the chuck , and the thread was 1.5 mm , the thread pitch was bigger like 3mm at the beginning and at the end, but in the middle was ok,(I think that I invented variable pitch threads.lol) I was using mach3 , and latter I found that in the parameters I should have ticked the exact stop.
one of these days I will fire the machine again and see how good it is (if it works) with a slower speed, but bear in mind.. that I have many years of experience with latest tech cnc lathes , and have observed that if you are screw cutting a 4mm pitch it shows 3.9 in the screen , maybe the thing want update the screen fast enough.
regards
Mariano