Hole size calibration

This is a test print for determining hole size adjustment. This is my solution to the problem that when you calibrate the printer fir accurate external dimensions, the holes are of wrong size- in my case they are too small. This can have many causes, such as wrong handling of holes by the slicer program, over-extrusion, thermal shrinkage and slight shift of hole position between layers resulting in hole edges partly covering up the hole from a different side in each layer. To use this, you print it at 100% size in X and Y, and without any raft or brim. Z size can be thicker and then it will be more accurate, but more material will be used, and having at least 5 layers would be nice to account for hole shift between layers. Then, you measure the resulting holes with calipers and enter both theoretical holes and actual holes into a spreadsheet, and do linear regression (LINEST should be English equivalent of REGLINP) where real holes are the "X" and theoretical are "Y". this returns the