Re: [CAD_CAM_EDM_DRO] Resonance in steppers

Jack Ensor wrote:

>
> Software is EMC2, motor driver is quadrature and not capable of
> micro-stepping, using Axis.ngc. Motors are synchro-syn 840 in-oz being
> driven at 5.5 amps and stepping down 2.5:1 in the timing belt pulleys to
> a .2 in/rev ball screw. Setup is on a 70's vintage BP that had been
> retrofitted with balll screws and a Bandit CNC sometime in its history.
>

Hmm, well, if you can borrow a Gecko 201 drive to compare, you
will be amazed. I think the only other choice would be a
viscous damper. You put a couple steel plates on the motor
shaft, and a free-spinning plate clamped between them. Some
viscous material between the inner and outer plates absorbs
vibrational energy into heat. Some are made with a sealed
annular cavity filled with STP, others are made with rubber-like
sheets.

The quadrature (or wave) drive pretty much eliminates step/dir
timing as the cause. But, try turning off backlash (set value
to zero) and repeat. If that fixes it, I think there is a new
update to make backlash compensation work better. If the
backlash correction move is made too abruptly, the steppers will
skip some multiple of 4 full steps. Since the backlash
correction is always made at axis reversal, it wouldn't cause a
stall, like resonance would because that happens during motion.

Jon