Differential bed adjusters

These are differential adjusters for Mk2B heater pcb and borosilicate glass bed surfaces, a companion to my Mk2B Bed Mod project: https://www.thingiverse.com/thing:2477091

The adjusters are in two parts, the lower part has an internal M4 thread, 0.7mm pitch, and an external thread, 1.0mm pitch. The upper part has a matching internal thread, 1.0mm pitch.

So, as the lower part is rotated 360°, it moves down the M4 thread by 0.7mm, but the upper part moves up by 1.0mm. The net movement is thus 1-0.7=0.3mm.

In short, very fine adjustment is possible.

The upper part has a recess for the heater plate, the peg should locate with the hole in the corner of the pcb. The upper walls are designed with some spring in them, the glass will be a tight fit, but the plastic will expand slightly as it warms up.

There are three versions of the upper part here, for 220x220x3.8mm, 220x220x3.0mm and 214x210x3.0mm glass, choose the one appropriate for your glass.

I printed mine form PETG, an