A few points become somewhat obvious by studying all of the above pictures and measurements. The first point is that the width of the groove in the roll chuck is at least 0.060". Otherwise, a 0.055" drive pin would not be able to fit into the groove. The second point is that the diameter of the hole in the chuck, into which the pin on the music roll must fit, is at least 0.205". The diameter of the drive pins (on the right end of the roll) on the 65-note rolls I checked varied from 0.160" to 0.190". The third point is that the diameter of the chuck seems to vary from about 0.350" to 0.450".

In an attempt to try to make a little more sense of all these very exact measurements, I decided to round them up or down to what I refer to as "human numbers". So, the 0.060" groove in the roll chuck is more than likely 1/16" wide (0.0625"). Therefore, the drive pin that fits into that groove would be 3/64" (0.0469"). The diameter of the hole in the chuck would most likely be 7/32" (0.2188") or perhaps 13/64" (0.2031"). Next, the diameter of the chuck is the most difficult measurement to 'standardize' because in all BUT the 65/88 note players, it's diameter is irrelevant to the operation of the drive system. This is probably why there seems to be such a wide difference (variance) in the diameters of the mating holes in the adapters, which ranged from about 3/8" to 7/16".

Lastly, the one measurement that is a little illusive but extremely important is the distance that the adapter will move the 88-note roll to the left. However, upon close examination, it became clear to me that all of the adapters would move the 88-note roll exactly 1/4" to the left. Obviously, this is very important since the relative position of the roll has to line up with the existing tracking sensors. Also, the width of the music roll paper is 11-1/4" for both the 65-note rolls and the 88-note rolls.