I’ve been working on a home built plasma machine, using a Hypertherm Powermax 65. Everything works OK, but I’m really wanting to dial the machine in a bit more and try to get it to cut smoother. I have attached some pictures, you’ll notice an inconsistent cuts when performing arcs/circles and a little bit of extra kerf I suppose. It’s also hard to tell if the machine feels jerky when putting my hand on the torch during a cut.
I built my CNC plasma as well, and it also has laser and milling swap-able heads. As such, I have discovered axis acceleration config in the grbl controller to be a huge factor in how smooth the XYZ axes move through corners, cutting smooth curves and straight lines on entrance and exit of corners. When running plasma and routing processes, because of the mass of the heads and resulting mechanical resonance when direction change occurs, I dial down the XY axes acceleration configs to 400mm/sec2, but when running laser (a much lighter head weight) I can dial it up to 800 or 1400mm/sec2 depending on the motion patterns of the job.
So once you make sure pinions or gears and belts are tight and tensioned correctly, then perhaps experiment with axes acceleration values.
Also, consider taping a marking pen to the torch and you can test and dial in the motion using paper instead of cutting steel.