I don't need massive speeds out of the machine. I'm happy with the 2m/m jog speed I have set on my current machine. That would be 100RPM at this pitch.

At this speed I'm guessing voltage isn't a huge issue. I do have a 24v/20A industrial switch mode supply that I can use for this project. Equally, if it's required I can throw a toroidal and some fat caps in a box.

I just need to figure out how much grunt I'm going to need to move the Z axis now! Sure I'll find a Nema 23 that can do the job.