Re: [CAD_CAM_EDM_DRO] Resonance in steppers

At 02:32 PM 5/28/2007, you wrote:

>I am losing and gaining position error as my system goes through the
>gcode I feed it. I suspect it may be due to stepper reonance. Is
>there any gcode that would pinpoint that this is the problem. In
>other words how can I find the sensitve velocity that triggers the
>resonance.

Back when I was servicing precision
photoplotters, we used a pattern of concentric
circles plotted with a small aperture. In your
case, a very fine cutter would be a good
choice. Since the servos go through a large
range of speed variations while plotting a circle
and your eye can probably spot issues very
easily, this is a good test. Another is lines at
1º increments if the circles don't show errors.

One "fix" is a rubber mounted dampener (sort of
like the harmonic dampener on a car engine) which
prevents torsional vibration build up. Some of
the ringing expends its energy in heating the
rubber, rather than making the steppers lose sync.

David G. LeVine
Nashua, NH 03060