Honestly i've never seen grbl cause non-symetrical parts. This will in the end boil down to something mechanical i think. Chains are good for timing, but not for motion, because one or two links can be longer than their neighbors. That may well be why it looses symmetry
It happens with the drive system completely disengaged. The motors are still making unexpected movements. Just computer, blackbox, motors connected.. nothing else.
This machine has been running pretty much non stop for months. The chain is fixed to the moving axis and is twice the length of the axis so the same position of the machine always reflects the same part of the chain. Like it doesn’t loop around so no common chain links. Also rotating the drawing gives the exact same results.
Also it’s non symmetrical but still completes the contour. The 3 small slots on the cut out I was using all have the exact same dinky part even though they are impacted by a different part of the chain.
