Re:

Jon

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<big snips all over the place>

> From: Jon Elson <jmelson@...>
>Subject: Re: Re: Closed loop steppers

>Well, yes, there is a jerk during a crash

Yes, and it was me! I wired the two prox switches in a tool measuring
stand backwards and when we measured a 3/8 drill bit the axis went
into rapid when it touched the first prox. Other than the butt end in
the tool holder, we never found even a sliver of the bit nor heard it hit
anything. When I looked around, the operator was checking himself for
major blood leaks. I was properly humbled. (some will say, "Yea but
you got most of it back." :-)

>In my own EMC / servo setup, EMC is recomputing velocity 1000 times
>a second, but the servo amp is actually providing higher bandwidth than
>you would get from EMC, which the Nyquist theorem would limit to
>less than 500 Hz.

Knew a Nyquist once. He was a grounds keeper. What's the theorem and
why is 500 Hertz a theoretical limit here?

Ray