0.2mm square vs. calibration slide

Nothing like proving your results. On the left we have my notional 0.2mm square (somewhat dusty by now) scratched into a sharpie-covered slide. On the right we have my new 0.01mm/div calibration slide. The small squares in the centre are 0.05mm a side each. So yes, I'm at about 0.2mm and can prove it. I'll freely admit I need to get my steps/mm dialled in a bit better but my efforts are pretty much within the error of line widths. With the big microscope though it's possible to see that even with the (relatively) chonky hypodermic needle tip the interior corners of the square are nice and sharp.

We can also see that the hypodermic tip is cutting a swath about 25 microns in one direction and 50 microns in a perpendicular direction, which one might expect as the things are obliquely sharpened.

The image of the square is at an angle basically because I mounted the slide in the μRepRap at an angle when I cut it. Bits of equipment just got in the way...

I've made headway into being able to set up the Z axis in software, so I might risk a slightly sharper, conical tip. I'll make one out of 0.3mm wire and try not to make it too pointy.