My little home built mill, drilling .035 diameter holes in stainless,the drill dulls, starts to scream and then breaks off in the part! Not so easy to get it out. I grab the mouse, search for the pointer, manuver it over to the emergency stop and the drill has already broken. So - - I put a 4 pole switch on the Z axis stepper motor and I can kill the down feed in a fraction of a second. Then I read, NEVER disconnect the motor while the drive is powered up!
Is this the reason I burnt the Z axis driver out on the Xylotec ?