Quote Originally Posted by Agathon View Post
If I go for conventional steppers I'll go with the AM822 drivers, but what size motor? The old steppers have a surprisingly small shaft (3/8") so Nema34s with 14mm shaft are a bit of nuisance. I see Nema23 3Nm motors with 10mm shafts - http://r.ebay.com/KuT9Ez - Are these big enough though?
Ok well first need to check if the machine is fitted with Ballscrews not just lead screws which you are calling Ballscrews.?

If ballscrews then 3 or 4Nm Nema 23 motors will probably work. I've fitted loads of Both 3 & 4nm motors and to be honest see very little difference between them in performance terms so wouldn't stress over which to use. The Key is buying ones with Low inductance. No higher than 4mh ideally closer to 3mh.
These are better motor and will fit your needs.
https://www.cnc4you.co.uk/Stepper-Mo...H401-03-Nema23

If you speak to them Don't Let them Bullshit you into believeing there drives are as good or better than Leadshine AM or EM they are not.!