Neiko caliper fixture for calibration - Prusa i3 MK3

thingiverse

This is a fixture that allows you to easily mount a Neiko 01407A Electronic Digital Caliper on the Prusa i3 MK3 extruder axis rails in order to calibrate the bed of the printer. Why should you use this? Well: (a) There are plenty of forum posts that describe the inaccuracy of pinda probes at different temperatures. (b) This jig measures the distance from the rails to the print bed. It is a direct measurement of what your printing head experiences. This measurement is not impacted by any software calibration adjustments. The process is more direct (and in my opinion, more accurate) than using the probe. The simple jig is easy to use: (1) Slide the Neiko caliper in from the side of the main black. The top of the caliper should be on the "top end" (i.e. the side with the diamond cutout). The larger hole in the side of the block is for the bottom of the caliper where there is are two screwed-in bars (2) Slide the caliper toward the top of the main block until it stops. (The key has a step on it which matches a cutout in the block - the caliper will eventually rest on this step). Moving the caliper toward the top will allow the key to slide in without getting caught on the caliper itself. (3) Insert the key with the "step" on the bottom and facing into the block (see picture). (4) When the key is flush with the outer surface the two diamond features should be square with the holes. Push the key down and everything should be secure. (5) Mount the jig onto the rails. Tolerance around all the fitted pieces should be 0.5mm. My printer has a good first layer calibration which resulted in a sliding fit.