Quote Originally Posted by r0bsk1 View Post
I've got these steppers from Zapp and plan to use MA860 drivers with a 70v+ PSU.
WHY.?? . . . . far far to big and will restrict performance not gain. To get any decent performance then you'll need far more than 70V and really need to be run using 240V drives.

Personally I'd ask about returning and get something more suited. From what you're proposing using rotating nuts then 3-4 Nm would be enough on 70V. Even 6Nm 34's would be OTT using rotating nuts esp if twin driven X axis, and then still restrict performance compared to 3Nm 23's.!

Bigger is NOT better and on this machine would be restrictive.!!