I’m running a custom setup, PoKeys 57CNC control board with mach3. When trying to enter g01 commands via MDI, the dro reads innacurately from actual movement. I can do a “g01 z-0.1” and using a digital indicator can confirm it comes within ~0.002” of 0.1” of movement. However, mach3 will read up to 0.06” off of the accurate measurement.
Additionally, if I enter the same command multiple times, mach3 will get closer each time until finally accurate (it might overshoot by 0.04, then after entering again overshoot to -0.03, then on the third time read something like 0.001)
My question is, what might be causing the DRO within mach3 to read differently from what pulses were actually sent? I was under the assumption mach3’s dro got its reading based on these pulses, so it makes no sense to me that it would read innacurately while the machine itself moves accurately


Thus far:
- making changes to exact stop/CV mode makes no difference
- Changing acceleration makes no significant difference (it normally sits at 45 in/s/s. Changing it to 10in/s/s or 80in/s/s didn’t change anything)
- Using g00 vs g01 makes no difference
- Using a slower feed-rate may improve accuracy slightly, but its still off by as much as 0.03” at 6 ipm which is way out of tolerance
- changing my microstepping (both in motor tuning and on my drivers so that it still moves ~1” when told to) makes no difference (currently running at 6400 steps/in)