Just out of interest, I thought I would see where the stepper positions itself with repeated homings using an inductive proximity sensor and a 5mm pitch leadscrew.

https://www.dropbox.com/s/xayeqtbo8l...P0009.AVI?dl=0

The video shows the stepper coming back to the same angular position and I tried it out 6 times with the same result, before I set up the camcorder.

I will leave you to draw your own conclusions about the necessity for a chopper

Cheers

Rob-T