631
General Mach Discussion / Re: (Mach3) Can't figure out issue with G31 Command (Probing)
« on: June 28, 2022, 09:30:38 PM »
Hi,
When the probe is tripped the machine decelerates to a stop, so yes there is overtravel, but 0.3mm? No way, even my old stepper driven mill which had acceleration of 375mm/ss stopped with 4um after probe trip when decelerating
from 100mm/min. My new mill has acceleration of 1500mm/s2, ie 0.15g , and that's detuned from its rated 0.27g rated deceleration, so the over run is 1-2um. If you have overtravel of 0.3mm your machine has too
low acceleration to probe, fullstop.
Craig
Quote
To summarize what I did with the G31 in the end, was just to use it as code to stop the machine from moving when the probe tripped. Unfortunately, after repeated tests, I found out that no matter how slow I did de probing, the machine would go about 0.3mm lower from the contact point. From what I tested, it seems that it has to do with how the G31 command is coded, it is either too slow or doesn't properly tell the machine to stop right when the Digitize LED is ON. It just keeps going lower after the probe has tripped.
When the probe is tripped the machine decelerates to a stop, so yes there is overtravel, but 0.3mm? No way, even my old stepper driven mill which had acceleration of 375mm/ss stopped with 4um after probe trip when decelerating
from 100mm/min. My new mill has acceleration of 1500mm/s2, ie 0.15g , and that's detuned from its rated 0.27g rated deceleration, so the over run is 1-2um. If you have overtravel of 0.3mm your machine has too
low acceleration to probe, fullstop.
Craig