Very good read. Thanks.
Fateh
On Thursday, 7 May, 2020, 5:45:55 pm IST,
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Today's Topics:
1. Re: Fluctuating RPM using CUI ATM 10 encoder (Gene Heskett)
2. Re: Fluctuating RPM using CUI ATM 10 encoder (Gene Heskett)
----------------------------------------------------------------------
Message: 1
Date: Wed, 6 May 2020 23:30:19 -0400
From: Gene Heskett <ghesk...@shentel.net>
To: emc-users@lists.sourceforge.net
Subject: Re: [Emc-users] Fluctuating RPM using CUI ATM 10 encoder
Message-ID: <202005062330.19255.ghesk...@shentel.net>
Content-Type: Text/Plain; charset="utf-8"
On Wednesday 06 May 2020 22:20:12 Dan Henderson wrote:
> I?ve confirmed the fluctuation occurs when spindle-at-speed is
> configured. When I remove this feature, the spindle rpm appears to
> stabilize. It?s almost like it gets caught in a loop trying to chase
> its tail.
The clues would tend to point in the direction of the output of the
spindle-at-speed signal somehow getting into the feedback loop to modify
the feedback value.
Check, and then recheck your hal file for some sort of coupling that's
probably unintended. Look at otherwise identical modules you've used
more than one of and make sure the unique marker such as an instance
number is correct, it could be a classic off by one typu. Such as that
will eat your lunch. In rare cases you may have to survey the running
system with "rockhopper", (google for it, pain in the butt to use but
its also very very good at what it does, which is to graphicly trace
every active signal in a system.) I'm not a touch typist, never got that
far in school, and my code is often contaminated with such stuff I have
to go back and fix. I've had to use rockhopper, several times. The
output by the time its printed and pasted/taped up, can occupy a 4x8
sheet of plywood. But it also works.
Any "spindle-at-speed" signal you generate, should connect only to motion
but I've forgotten the exact name of that pin so dbl-check man motion to
get it right, and nothing else, (except maybe an led in a pyvcp
generated gui) as motion uses the lack of that signal to hold off the
initiation of a synchronized move such as a g76 or g33.1 so its not
started if the spindle just started, generates an index but is not yet
up to speed.
Because there is an acceleration delay as the axis being moved gets up to
locked speed, if the spindle is not at a constant speed, this delay will
vary causeing an offset in the final locked positions, screwing up the
thread, so LCNC goes out of it way to make sure this signal is also
true. For the same reason you can't start a thread slow, see that its
going to be ok, then grab the rpm slider and crank it up, the diff in
the accell delay will wreck your thread by causeing an offset between
the slow pass and the sped up passes.
Good luck with the hunting, Dan. And stay well. I just read tonight
there are children that appear to have a different illness from this
covid19, causeing extremely high fevers, heart attacks and strokes. And
here I'm worried because I'm in my 86th trip around this star.
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
Genes Web page <http://geneslinuxbox.net:6309/gene>
------------------------------
Message: 2
Date: Thu, 7 May 2020 07:10:05 -0400
From: Gene Heskett <ghesk...@shentel.net>
To: emc-users@lists.sourceforge.net
Subject: Re: [Emc-users] Fluctuating RPM using CUI ATM 10 encoder
Message-ID: <202005070710.05688.ghesk...@shentel.net>
Content-Type: Text/Plain; charset="utf-8"
On Wednesday 06 May 2020 23:30:19 Gene Heskett wrote:
> On Wednesday 06 May 2020 22:20:12 Dan Henderson wrote:
> > I?ve confirmed the fluctuation occurs when spindle-at-speed is
> > configured. When I remove this feature, the spindle rpm appears to
> > stabilize. It?s almost like it gets caught in a loop trying to chase
> > its tail.
>
> The clues would tend to point in the direction of the output of the
> spindle-at-speed signal somehow getting into the feedback loop to
> modify the feedback value.
>
Dan: Be aware if using master, that the syntax has changed, due to new
multiple spindle control abilities LinuxCNC has grown, it is now
spindle.N.at-speed, where for you with one spindle, N is 0. And I've
some configs to fix too...
Did you find anything yet?
> Check, and then recheck your hal file for some sort of coupling that's
> probably unintended. Look at otherwise identical modules you've used
> more than one of and make sure the unique marker such as an instance
> number is correct, it could be a classic off by one typu. Such as
> that will eat your lunch. In rare cases you may have to survey the
> running system with "rockhopper", (google for it, pain in the butt to
> use but its also very very good at what it does, which is to graphicly
> trace every active signal in a system.) I'm not a touch typist, never
> got that far in school, and my code is often contaminated with such
> stuff I have to go back and fix. I've had to use rockhopper, several
> times. The output by the time its printed and pasted/taped up, can
> occupy a 4x8 sheet of plywood. But it also works.
>
> Any "spindle-at-speed" signal you generate, should connect only to
> motion but I've forgotten the exact name of that pin so dbl-check man
> motion to get it right, and nothing else, (except maybe an led in a
> pyvcp generated gui) as motion uses the lack of that signal to hold
> off the initiation of a synchronized move such as a g76 or g33.1 so
> its not started if the spindle just started, generates an index but is
> not yet up to speed.
>
> Because there is an acceleration delay as the axis being moved gets up
> to locked speed, if the spindle is not at a constant speed, this delay
> will vary causeing an offset in the final locked positions, screwing
> up the thread, so LCNC goes out of it way to make sure this signal is
> also true. For the same reason you can't start a thread slow, see
> that its going to be ok, then grab the rpm slider and crank it up, the
> diff in the accell delay will wreck your thread by causeing an offset
> between the slow pass and the sped up passes.
>
> Good luck with the hunting, Dan. And stay well. I just read tonight
> there are children that appear to have a different illness from this
> covid19, causeing extremely high fevers, heart attacks and strokes.
> And here I'm worried because I'm in my 86th trip around this star.
>
> Cheers, Gene Heskett
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
Genes Web page <http://geneslinuxbox.net:6309/gene>
------------------------------
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