How to Measure
Basically we need to start with the measurement from skin-to-skin. This measurement needs to be accurate to within 1/16 th of an inch.
Start with a drum that has one or both heads removed. Use a tape measure to get the distance from the very tip of the bearing edge to the opposite tip.
From this measurement we can figure out the amount of trim back and deliver a piece of finish that you won't need to trim.