Thanks guys, as ever.

That makes sense then - stall detection = a way of reducing scrap metal, whereas servo motors = actual error correction

I will definitely be replacing the slightly bent ballscrew - it was the first one I purchased and I probably bent it due to uninformed rushing when I originally put the machine together. Chalked up as experience and the old one may be able to be used in a shortened format on a new z axis or on the lathe if I convert that (I guess I can machine it or have it machined), so not a complete loss.

Cheers


Chris