Watching one of @PhilJohnson’s videos on another topic I saw him cutting two colocated squares, but one as an inside cut and one as an outside cut. Then he casually mentioned in the video that any fuzz between the two was as a result of the bit being slightly smaller than specified.
That got me thinking that a relatively simple way of calibrating the size of a given bit would to cut such squares and incrementally reduce the defined size of the bit and re-carve until the fuzz between them disappears. That might be easier than the other method of cutting a single groove and then trying to measure that groove accurately.
Does anyone already do something like this?