4th axis brake enquiry

[m_c]

Would a closed loop stepper motor be any use? I would have thought the "closed loop" would prevent un-requested movement and behave a bit like a brake.
regards
bob

Yes and no, would be the answer to that.
The big benefit of using a closed loop stepper in this application, would be they do tend to self correct to a certain amount so would move the stock back into position, and they would let you run things far closer the motors limit, however any movement could still scrap the part.
It's a case of balancing up your needs, and what compromises you can make.

I have just thought of one option if you don't need much speed, how about mounting a stepper onto a cheap rotary table?
They should be adjustable for backlash, and they'll give you lots of gearing in a compact format