At certain speeds, you have the servo motor moving at pulsing
speeds, just like the stepper that it is pretending to be, and
thus have the resonance problem again.

This is nonsense. At no time is the DC motor pretending to be anything. It
is being itself driven by a PWM voltage always. Anything resembling
resonance issues in steppers is due to either improper tuning or exceeding
the specifications of the system.

"DoN. Nichols" wrote in message
...
God is dividing by zero ---