I’ve found recently that ferrites really help with this. The electrical noise from large steppers is really erratic, but responds well to ferrite beads with 2-3

I’ve found recently that ferrites really help with this. The electrical noise from large steppers is really erratic, but responds well to ferrite beads with 2-3 wraps. I put one at each end of the cable, since back-EMF is very real in large steppers.