RE: [CAD_CAM_EDM_DRO] Re: Video of my resonance

I turned up the volume really high and played the video again. Then I
looked at your list of parameters. Is it possible that a combination of two
things are really happening here? The sound is much like the beat frequency
of a twin engine aircraft where the props aren't perfectly synchronized.
But you state that the motors are slaved.

So here's an idea. What is happening is that at the speed of interest,
you're at some natural resonance of the entire system even though you are
micro stepping. Although the motors are slaved, and each steps N
micro-steps, they may not be physically slaved where the rotors are in
exactly the same position. So one motor is at .5 of a full step while the
other motor is at 0.75 of a full step. Now if each moves 10 micro-steps
then each motor will still be .25 of a full step apart but just at a
different rotor position.

Add that the two racks may not be aligned absolutely perfectly and the
loading on the motors as they move through there micro-steps will change
hence the beat frequency as they turn. At higher speeds, the resonance
situation doesn't exist or if it does it's at a much higher frequency and
the two don't happen long enough for it to be noticed.

Just an idea...


John Dammeyer

>
> Two 1200oz/in stepper motors. One slaved of another. With a
> timing belt reduction.
>