Re: [CAD_CAM_EDM_DRO] EMC Fix Ideas

I know from experience that ramping algorithm's can cause lost steps for
some. It usually happens when one axis is using alot more PPI thean another.
The problem seems to be that the high PPI axis gets a single pulse for every
few on another axis ( in a turn or something) and the ramping algorithm
fails to notice that the high PPI axis get two pulses too close together.
This causes a jog ( or missed step) on that axis. I have the same thing
happening
on one of my machines when doing engraving, which has a lot of quick Z
movements. My Z-Axis is 3450 PPI where my X and Z are only 500PPI. It only
happens under some circumstances on mine, and I'm trying to rewrite my
ramping algorithm to prevent it. Maybe thats what was happening to you.

Art

----- Original Message -----
From: <Ozzie@...>
To: <CAD_CAM_EDM_DRO@egroups.com>
Sent: Sunday, September 03, 2000 4:37 PM
Subject: [CAD_CAM_EDM_DRO] EMC Fix Ideas


>
> A while back I posted my problems with getting my CNC setup to work,
> under Lost steps.
>
> Many thought that my problem was with electrical noise, that the
> wiring of my Camtronics driver was at fault, etc.
>
> I then discovered, with some help from Alan Rothenbush, that CNCPRO
> worked almost flawlessly.
>
> My problem is that I really want to use a closed loop system, (EMC
> with the Mauch DRO card). I already have the card and motors with
> encoders are on the way.
>
> Toward that end and any possibility that my Camtronics board was
> wired
> in less than an exemplary way, I pulled all the wires and re-wired.
> All 37 volt wires are 14 ga twisted pairs, all 5 volt wires are 18 ga
> twisted pairs, all signal wires are 22 ga , signal twisted with a
> ground, direction twisted with a ground, all motor wires are 18ga, Aa
> twisted and Bb twisted. The wire motors from the case are shielded
> and
> grounded. ALL grounds run to the big capacitor, no exceptions! It's
> beautifull!
>
> But the results are the same; CNCPRO will execute twenty moves at
> virtually any speed, and return to it's start point within a half
> thou
> on a cheap dial indicator. EMC will not do two moves within .005".
>
> The last time I posted the problem the discussion wandered to what
> should be done to improve EMC, and that is fine. But, there must be
> many out there using EMC on a small setup like mine with success.
> Although Tim Goldstein setup my EMC, (and by the way posted my
> setup),
> I'm wondering what areas of the ini files I might try changing to
> make
> things work for me now rather when an improvement for EMC comes along.
>
> *****Please bear in mind that the problems are at slow speeds, well
> under 1000 steps per second. Higher speeds work fine!**** I think
> that eliminates acceleration or velocity settings, (although I have
> tried changing them both, to no improvement).
>
> I understand that the closed loop will probably cure the problem,
> maybe the new motors will, but I have a feeling that I should make it
> work as well as possible before adding to the hardware.
>
> Looking for ideas,
> Thanks Jerry
>
>
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