RE: [CAD_CAM_EDM_DRO] Re: G320s, New and Improved!

> -----Original Message-----
> Tim Goldstein wrote:
>
> > I just got an opportunity to test out the new and improved G320 drives
> >
> > Next up, the problem I had with interference is gone.
> Previously if I put a
> > dial indicator on the table and against the spindle and made a series of
> > .100" jogs I would get measured movements of anywhere from
> .096" to .104".
>
> Do you know what caused this?
> Do other people have this same problem?
> What are the fixes?
> I bought two of these drives last winter to run the X and Y axis
> on my ball
> screw mill and am still slowly getting them going.
> I was at the point of only have to wire the encoders and come up
> with a second
> set of limit switches when I learned of the recommendation to use
> shielded wire
> on the power leads so that is now added to the list but I am
> going to try it
> first without shielding as it is already wired.

I have not put a scope on it to verify, but my guess is that the PWM on the
motor power lines were causing enough interference on the encoder lines that
it was being seen as encoder counts. It seems to be a problem that crops up
particularly as the wiring gets longer. Besides the new revision of drives
other preventive measures are capacitors at the encoder power lines and good
shielding and grounding practices. I have also been told that using
differential line drivers at the encoders and recovers at the drivers is
quite effective. Will soon be trying this as well on some of the old
revision units.

> > No particular pattern to the discrepancy.
>
> What do you mean, the error always varied or the error came and went?

Yes to both. It came and went and it varied.

Tim
[Denver, CO]


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