On 4/23/23 09:13, gene heskett wrote:
Petter;
Dummy questions:
I only have 1 machine actually using pid's, my cnc'd Grizzly G0704.
My one pass at trying to do it by hand from the recipe in the man page
wasn't 100% successful, leaving me with a tiny hunt of about .0005" at
about 1/2 hertz. Axis Z.
This machine also has an A axis, not always mounted and hooked up,
currently dismounted but not disconnected as there's no way to
disconnect w/o making a completely new set of .ini and .hal files. We
really need a way to add or subtract an axis on the fly without writing
a new config.
But that is just a comment. But as long as is there, it sure needs
tuning. I can run much faster than it is allowed to, but will crowbar
its psu if it overshoots because of the motor armature inertia. I have a
hal programmed turn-around in the spindle so I can reverse it from 3000
to -3000 and back in around 350 ms, but not worked out how to duplicate
that for the A. Yet...
That 4th axis is a clone BS-1, sorta big for a G0704, currently
configured as axis A. It has an estate gate servo motor with a high worm
ratio drive, hooked to the worm of the BS-1, so its both slow, and
servo-wise, which has a huge armature mass to control so it overshoots
easily. Driven by a pwmgen and an auto seat motor controller, and must
be driven slow enough that the pid can slow it as the position is
approached, slow enough it does not overshoot because if it has to
reverse, its too fast, and crowbars its psu. No real damage, but the
psu takes around 2 minutes to cool before it comes out of the overload
shutdown. I really need to make a different worm motor setup.
All that description leads to: can I edit your script for this 4th axis?
Reading between the lines, I assume the linuxcnc its going to tune is
running so it can pick vars from the running but idle linuxcnc?
Assumptions prompted by the fact that I configure so machine power is
all off if F2 is not enabled. Your script has no overrides that I can see.
Thanks Petter. Take care & stay well.
In about 20 hours, Petter R. has not answered a direct mail as he is not
subscribed.
His script does not work with master. Even with tune_effort set to .002,
and it says it going to move x t0 0.00499999, the first move is both
violent and terminated with a thump as a following error is reported and
followiing error in his script has been expanded to 1000 from 100.
perhaps I'm running it wrong? Anybody want to write a script for this?
I've tried it on all 4 axises of this machine, nothing of note reported
other than the following error and the 1st 3 axises are now slowly
hunting by a fraction of a thou. A is not but its like molases in
january anyway.
My experience with pid's has been far less than friendly to the extent
that the last 2 machines I built are without pids. And they Just Work
when I hit F2 to enable machine power, then home them and the then do
exactly what I ask in gcode. I suspect there is a pid in the drivers for
the 3 phase stepper/servo's. But from my poiint of view they get to
where linuxcnc tells them to go, or hitting an non-movable block, can
and will shut down linuxcnc in it tracks in nominally 1 millisecond.
If you are going to force us to use the at-pid, give us a tuning script
that just works, my machine is now so screwed up its unusable for gcode,
and only safe at ultra creep speeds to jog from the keyboard. It took me
over 2 hours last week to cut a belt clamp in 2 to use it in a 3d
printer, because I could not move it more than a thou w/o a 10 second
wait between 1 thou moves.
I am about to rip the pid's out, If I have to change the motors to
stepper/servo's I'll do it. Might get by for $750 for all 4 axises. So
what do I do? Your call.
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, 1940)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
Genes Web page <http://geneslinuxbox.net:6309/>
_______________________________________________
Emc-developers mailing list
Emc-developers@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-developers
