3D filament shrinkage calibration test

thingiverse

This is a 3D printer filament shrinkage calibration object that is inspired by the technique demonstrated by Clough42 in his video: https://www.youtube.com/watch?v=0dFThbwAx2Y. To use this object you need 4mm metal dowel pins (I got mine from McMaster: https://www.mcmaster.com/93600A474). Each end of the design has holes from 4.2mm (left) to 4.5mm (right) - you insert the pins in the tightest corresponding holes and using calipers measure the inside and outside distance between the pins. There are raised rectangles to help keep the calipers parallel to the pins. You then take the two measurements and average them to find the distance between the centers of the holes which should be close to 125mm. To calculate the percent compensation value you then divide 12500 by that average. For example with one brand of PLA I got dimensions of 120.22 and 128.64mm which averages to 124.43mm. 12500/124.43 rounds to 100.46%. So with this particular plastic if I uniformly scale the model by 100.46% I should compensate for shrinkage. I thought Clough42's technique was especially smart because using the distance between two inside features means that any under/over extrusion of the outside perimeter is naturally factored out, unlike if you simply printed a cube and measured the outside dimension.