G96 not responding/clipping to max rpm speed assigned

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30 Apr 2020 14:12 #166219 by leito1489
Hello to all,

I'm more used to the mailing list so it's no common for me to post here, but since here I see a lot of movement may be this happened to someone else.

I'm running Debian Wheezy with LinuxCNC 2.8.0 version. The machine is a Mazak QT20 lathe that was recently converted. The spindle motor is driven by a Yaskawa V1000 VFD and I'm using as speed command reference a pulse train that I'm generating with a mesa 7i52s. The feedback is a 1024 PPR encoder mounted on the spindle with a 1 to 1 ratio. The spindle is working fine, if I issue an mdi command I can vary the spindle speed without any problems. The readings on the encoder (although noisy) correspond to the ones in the commanded speed I see on the motion component.

The problem is, any time I issue a G96 code, in this case G96 D600 S40 M4, the spindle accelerates to the maximum speed programmed (600 RPM) and makes all the cut in that speed. The G96 command seems to work, because If I set different max speeds I get different feed rates, and also I can see the feed rate indicator being a little noisy because of the encoder velocity feedback. The problem is I'm not getting the RPMs of the spindle to vary acording to the diameter of the X axis. I'm using G54 coordinate system and the tool diameter is 0 at the line of the spindle axis. I have negative values almost on all the X axis in machine coordinates but I don't think that's a problem.

Please let me know if there is something I'm missing here and thank you in advance for your help!

Leonardo

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30 Apr 2020 14:17 - 30 Apr 2020 14:17 #166220 by leito1489
By the way, the spindle override slider on AXIS GUI doesn't work either. It only acts as a ON/OFF switch turning the spindle off at 0%.

I don't know if this is some kind of bug and I need to re install on another distro.
Last edit: 30 Apr 2020 14:17 by leito1489. Reason: wrong word

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30 Apr 2020 14:24 #166222 by tommylight
First you should fix the encoder issue, then have a read here, maybe there is something that will help while you wait for a response. I never used it.
www.google.com/search?client=firefox-b-e...+site%3Alinuxcnc.org

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30 Apr 2020 17:09 #166229 by leito1489
Solved!

I was using spindle.M.speed−cmd−rps to drive my stepgen and VFD and this pin sets to the maximum speed when in G96. I'm now using spindle.M.speed−out−rps and it works perfectly. But that makes me question the naming on these pins. Aren't all the CMD tagged pins supposed to be used to feed PWM, Stepgens, etc?
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30 Apr 2020 17:24 #166230 by tommylight
Thank for reporting back.
And analogout's are used for Mesa 7i77 for servo drives, but i am not sure how that is related to the cmd pin in PID, might be cmd is used for inside calculations and out is used for actual output.
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03 May 2020 03:39 #166465 by leito1489
Well, talking in the mailing list Andy showed me the source code and this is commented but not documented in the manuals.

Heres the link: github.com/LinuxCNC/linuxcnc/commit/a1c6...5afe590ebfcf1f25c309

Apparently the difference in the pins is for spindles that work with gearboxes.
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