Gmoccapy & 7I96 jerky movement
- ollied1981
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28 Dec 2021 21:42 #230176
by ollied1981
Replied by ollied1981 on topic Gmoccapy & 7I96 jerky movement
I managed to catch it! There's a section of g code that's milling a letter S in XY that seems to cause particular problems.
The outline shape of the plots is recognisably the same but for the good S as you'd expect the velocity commands are smooth WRT time and with the bad S they're very much not....
These commands come from the linuxcnc motion controller so it can only be something wrong with that?!
The outline shape of the plots is recognisably the same but for the good S as you'd expect the velocity commands are smooth WRT time and with the bad S they're very much not....
These commands come from the linuxcnc motion controller so it can only be something wrong with that?!
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28 Dec 2021 22:18 - 28 Dec 2021 22:20 #230177
by PCW
Replied by PCW on topic Gmoccapy & 7I96 jerky movement
It really looks like the feed-override has been changed between the two plots
(or the G64 settings)
(or the G64 settings)
Last edit: 28 Dec 2021 22:20 by PCW.
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28 Dec 2021 22:30 #230178
by ollied1981
Replied by ollied1981 on topic Gmoccapy & 7I96 jerky movement
Both plots are on the same timebase on the scope and at 100% feed rate in linuxcnc.... counting the divisions between the peaks on the pink trace it looks as though the bad S is running a bit slower, but maybe that's because whatever is making the waveforms is getting bogged down and that's why the bad one is also so ragged.
I still don't really get how this can be intermittent!
I still don't really get how this can be intermittent!
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28 Dec 2021 22:49 - 28 Dec 2021 22:49 #230179
by PCW
Replied by PCW on topic Gmoccapy & 7I96 jerky movement
OK so it really looks like the G64 /G61 settings are changed
Do you have G64 settings in the prefix of your gcode file?
Do you have G64 settings in the prefix of your gcode file?
Last edit: 28 Dec 2021 22:49 by PCW.
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28 Dec 2021 22:58 #230180
by ollied1981
Replied by ollied1981 on topic Gmoccapy & 7I96 jerky movement
No G64 in the gcode (attached). It's gcode output from the Fusion 360 EMC post processor.
The intermittent nature is the most baffling thing to me. Usually these things work or they don't!
The intermittent nature is the most baffling thing to me. Usually these things work or they don't!
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28 Dec 2021 23:08 - 28 Dec 2021 23:08 #230181
by PCW
Replied by PCW on topic Gmoccapy & 7I96 jerky movement
You need to have g64 settings (say g64 p 0.05 q 0.05)
in your gcode file or your trajectory settings will be whatever
was set by the last file that changed them...
in your gcode file or your trajectory settings will be whatever
was set by the last file that changed them...
Last edit: 28 Dec 2021 23:08 by PCW.
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28 Dec 2021 23:11 #230182
by ollied1981
Replied by ollied1981 on topic Gmoccapy & 7I96 jerky movement
I'll add that to the gcode and report back. Thanks a lot!
![:) :)](/media/kunena/emoticons/smile.png)
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29 Dec 2021 13:03 #230226
by ollied1981
Replied by ollied1981 on topic Gmoccapy & 7I96 jerky movement
Hi Peter,
You were right about the G64...
I'd made a macro for putting the machine in centre position using one of the example macros, and on inspection it had a G61 in it cancelling any G64. This is why restarting linuxcnc cured the 'fault'. Now I feel silly!
Thanks a lot for your help again.
You were right about the G64...
I'd made a macro for putting the machine in centre position using one of the example macros, and on inspection it had a G61 in it cancelling any G64. This is why restarting linuxcnc cured the 'fault'. Now I feel silly!
Thanks a lot for your help again.
The following user(s) said Thank You: tommylight
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29 Dec 2021 16:54 #230254
by PCW
Replied by PCW on topic Gmoccapy & 7I96 jerky movement
Yes, having an optional macro that changes a state variable can cause
tricky issues
Too bad LinuxCNC doesn't have "restore previous motion mode" gcode
tricky issues
Too bad LinuxCNC doesn't have "restore previous motion mode" gcode
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