Quote Originally Posted by m_c View Post
I used an opto slot sensor on my old lathe, and there was never any measurable variation. I used RS part number 480-5231 however I see that part has now been discontinued. The only problem was I had to make sure a bit swarf hadn't landed in the slot prior to homing, as I never bothered enclosing it.

The new lathe uses proximity combined with servo index homing.

You could combine a proximity or microswitch with a slot sensor on the stepper, provided you can add a suitable slot to the stepper/ballscrew, to essentially give you a poor mans index homing.
Does this need a 'receiving part' or anything that it can pick up in the slot?