Resurrecting this thread to update my status and trying to fix my biggest problem.
To update, I have retuned, mostly, and found my simple math needed work in determining my max velocity and accel. It was way oversized and now corrected KmotionCNC is able to rapid properly without rapids as feeds.
While retuning, I have noticed a new noise issue causing significant spikes in the encoder position noted in the plots, but not always and not consistent beyond most of them most of the time occurring at the end of the move test cycle. Where distinguishable, the spikes range from 40-120 encoder steps (my encoders are all 1k with quadrature for a total of 4k per rev). These are new and did not appear at all after I had gone through the grounding issues noted prior. However, I do now find there is very significant noise being generated by the snapamp at it's 30khz switching. When my servo power is off and the drives disabled, the multiple isolated power supplies are all quite and smooth on the scope. As soon as the power is on and the drive active, huge spikes every 30us. On the 5v for Kflop, the spikes are around 2.5v (I need to recheck since I forgot if it was 2 or 3v spike). The wave form is similar to what was noted in the older thread:
Newbie SnapAmp encoder connections (single-ended) - Page 2
Even with the noise, I am able to run gcode. The results are not always good. Although, the results are the same as from before the new noise issue. The major cut issue is scalloping randomly yet very consistent. Randomly as in I can run the same gcode in the same spot with different results of where the scalloping occurs. The images are of 4 discs cut with a patterned gcode along the X axis with my prior tuning. With my new tunes, I found similar results while repeating in the same spot.
I tried to keep the HDPE discs in the same x/y orientation to each other to note how the deep scalloping (some as significant as 0.025") start and stop inconsistently regarding the portion of the gcode and z elevation. When it does scallop, as you can see, it does it with a very consistent repeating pattern. The gcode should be attached here as well.
I do need to go back over the IIR filtering and rerun the bode plot after having adjusted my V,A,J, and PID (not using any D with the IIR seeming to do a better job so far). Any hope that my filters could be culprit here?
Thanks for any replies.