Hi Don,
This initially crossed my mind as well, but then thought .... anytime you intentionally stopped the spindle, you would go into reset. Loosing all reference, and would not be able to jog, or any other set-up without the spindle running.
I guess if all motion was stopped when stopping the spindle, and the drives didn't go off line there would be no pos. lost during a tool change. But, all reference would be lost.
Also , a question :
If the motor is a DC 90 or 180V , is there a relay coil that would work with the widely varying voltages ?
Thanks,
Russ