Problem when using G33.1
- garymcrobertpdx
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21 Oct 2013 07:50 #40114
by garymcrobertpdx
Problem when using G33.1 was created by garymcrobertpdx
Problem when using G33.1 If I set the spindle RPM to S60 or 100 and M3
the spindle rotates smoothly. But when I invoke a G33.1 it becomes jerky
causing the Z axis to also lurch in sync with the spindle as one would expect.
while this still works with larger taps #8 and up it is a problem with smaller taps
What would cause such a change in spindle behaviour and how to fix it?
the spindle rotates smoothly. But when I invoke a G33.1 it becomes jerky
causing the Z axis to also lurch in sync with the spindle as one would expect.
while this still works with larger taps #8 and up it is a problem with smaller taps
What would cause such a change in spindle behaviour and how to fix it?
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22 Oct 2013 19:24 #40164
by andypugh
That seems peculiar. If you Halscope motion.spindle.speed-out do you see a variability in the speed demand?
Replied by andypugh on topic Problem when using G33.1
Problem when using G33.1 If I set the spindle RPM to S60 or 100 and M3
the spindle rotates smoothly. But when I invoke a G33.1 it becomes jerky
That seems peculiar. If you Halscope motion.spindle.speed-out do you see a variability in the speed demand?
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23 Oct 2013 12:13 #40217
by jmelson
in the HAL files, what the hardware interface is to the spindle drive, etc.
I have used G33.1 on a Bridgeport with my own interface (the Pico Systems PPMC)
controlling a VFD via 0-10 V command, and also a minimill with my Universal PWM
controller, and one of my PWM servo amps. In both cases, I have a low-pass filter in the
velocity output to limit the rate at which the velocity can change. In the case of the minimill,
it was to prevent tripping the overcurrent of the servo amp. In the case of the Bridgeport,
the VFD could reverse the spindle faster than the Z axis could follow.
Your "jerky" motion -- does this occur immediately at spindle start, or does it occur when
the spindle reverses? If the latter, then it sounds like a filter might also be needed.
If at the start, then I'm confused, as that would usually be an M03. Or, are you giving the
G33.1 with the spindle stopped? If so, try starting the spindle with M03 first! I know that
works.
Jon
Replied by jmelson on topic Problem when using G33.1
I think you'd better tell us what is driving the spindle motor, how you control itProblem when using G33.1 If I set the spindle RPM to S60 or 100 and M3
the spindle rotates smoothly. But when I invoke a G33.1 it becomes jerky
causing the Z axis to also lurch in sync with the spindle as one would expect.
while this still works with larger taps #8 and up it is a problem with smaller taps
What would cause such a change in spindle behaviour and how to fix it?
in the HAL files, what the hardware interface is to the spindle drive, etc.
I have used G33.1 on a Bridgeport with my own interface (the Pico Systems PPMC)
controlling a VFD via 0-10 V command, and also a minimill with my Universal PWM
controller, and one of my PWM servo amps. In both cases, I have a low-pass filter in the
velocity output to limit the rate at which the velocity can change. In the case of the minimill,
it was to prevent tripping the overcurrent of the servo amp. In the case of the Bridgeport,
the VFD could reverse the spindle faster than the Z axis could follow.
Your "jerky" motion -- does this occur immediately at spindle start, or does it occur when
the spindle reverses? If the latter, then it sounds like a filter might also be needed.
If at the start, then I'm confused, as that would usually be an M03. Or, are you giving the
G33.1 with the spindle stopped? If so, try starting the spindle with M03 first! I know that
works.
Jon
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23 Oct 2013 21:38 #40228
by cradek
G33.1, like all spindle-synchronized moves, resets the encoder counts at index.
You did not give us any information that can tell us why this causes your spindle to become jerky, but I suspect you are using PID for your spindle speed, or doing something else similar with the encoder's position feedback that does not correctly handle resets.
If this doesn't lead you to the answer, please give a full summary of your spindle setup.
Replied by cradek on topic Problem when using G33.1
when I invoke a G33.1 it becomes jerky
G33.1, like all spindle-synchronized moves, resets the encoder counts at index.
You did not give us any information that can tell us why this causes your spindle to become jerky, but I suspect you are using PID for your spindle speed, or doing something else similar with the encoder's position feedback that does not correctly handle resets.
If this doesn't lead you to the answer, please give a full summary of your spindle setup.
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