Wednesday, March 25, 2026
Sudden probelms finding height, new levelling code
Something happened today, and I don't know if it's humidity, contamination, subtle probe damage, or what. But probing the aluminium foil touchplate got wildly inaccurate. I've put a microscope on it, and you can now not only see the probe pushing down and bending, but actually watch it push the entire XY Stage to the side when it contacts. The error spread in multiple contacts on the same point has gone from 4-6μm to as much as 50μm. I didn't believe this, so I've improved utils/levelling_probe.py with multiple point probing and a bunch of other command line parameters. Here's a sample couple of runs:
Damn, it seems to be happening. The probe is behaving OK, the movement is smooth and eyeballing suggests consistent with the numbers. It's just dodgy contacting. So, I'll make a new touchplate from different foil and see how that works out. Maybe try a different probe too, but another family event looms and I have little time.
At least it spurred me to improve the levelling utility.
