Wednesday, March 25, 2026
Tried another probe - it works
I switched back to a hypodermic needle probe. They're more rigid and have sharper edges than an ogival tip, giving better penetration of the oxide layer on aluminium. The improvement was marked:
The range of heights returned when repeatedly scanning a single point dropped to typically a micron or less. In this sample, only one point had a variation of 1.3 microns. So the scanned 2mm square was levelled to within the limits of the probe and foil surface.
Next step is to scan a larger square, then scan smaller squares within that one to see if the whole surface is generally level.
Practical takeaway is that ogival tips are not useful for bed levelling. This explains why I can't seem to zero a probe on the foil before deposition and invariably end up having to tweak it manually.
