On Mon, Jun 20, 2011 at 6:37 PM, YES NOPE9 <yes@nope9.com> wrote:

> One obvious thing to check is mechanical resonance issues.
> Change the rotational mass of your stepper motor.  Add a shaft ring or
> similar.  Then check to see if the noisy sections of the RPM curve have
> changed.  See if your waveform issues have changed.
> 99guspuppet
>

Unfortunately, I don't have easy access to extra random mechanical parts
since I'm 2000 miles from where the mechanical hardware was designed and
built, but I did try applying friction to the motor shaft with 2 fingers.
 The extra frictional load brought the current waveform a great deal closer
to a sine wave, mostly removing the second peak, but I had to nearly stall
the motor in order to produce the cleaner waveform.  Of course, adding a
frictional load is simply adding mechanical damping.  Increasing the motor
shaft's moment of inertia as you suggest should produce a frequency shift o=
f
the mechanical response, correct?  I will try to find someplace local where
I can get a part to add on to the shaft.

Thanks,
Jim
--=20
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