Hi

First post (of many I suspect).

I am converting an adcock & shipley 1es mill to cnc. I have raised the vertical head, added a dedicated vertical drive motor. Having serviced and set the gib strips I am happy with the machine and its time to look in more detail at the CNC conversion.

Right now I am favouring Linux CNC with MESA motion control. I feel stepper motors will suit my budget and expectations, combined with ballscrew conversion. Nema 34 for z axis and probably Nema 24 for x/y

The z axis carries a fair bit of weight, I did some calculations based on 5mm pitch ballscrews and this showed holding torque would be ok using a nema 34 motors. However I am concerned that the axis will back drive when the machine is powered off.

Anyone had any experience with similar problems

What kind of holding torque might a stepper give when not powered.

Regards Bally