Re: [CAD_CAM_EDM_DRO] Losing steps

art wrote:

>Hi Jon:
>
>
>
>>>>Of course a true servo system would detect this automatically, as it
>>>>checks
>>>>
>>>>
>actual vs. commanded position, say, 1000 times a second, and will go to
>e-stop
>immediately
>
> It should be noted that alot of people still get lost (gained really)
>steps in their servo systems due to noise on the
>encoder lines. I've seen this is many situations this year. It can be a
>bugger to track down because
>its always assumed that servo's cannot lose steps. Just thought I'd mention
>if someone appears to be losing
>steps in a servo system, its a good place to start looking...
>
>

Well, after building a new system, you HAVE to run it through its paces
to VERIFY
that it is working as designed! I have NEVER had this problem, and I've
been
running a 3-axis servo-controlled mill with my own retrofit since 1997.
I have occasionally had a runaway
when setting up a new system, when a plug falls out, a wire breaks,
whatever. I always
keep the current limit set low and my hand near the E-stop switch until
I gain confidence
that it is stable. But, I have NEVER had surreptitious gain or loss of
position in small
increments. (I can get a shift in the Y axis when I crash, as the
ballnut is not pinned in
place with dowels. but that is totally mechanical, not electronic.)

>
>

Jon