May I respectfully suggest that a defined diameter of take-up spool be
settled upon.  The fact of the matter is that take-up spools are not
all of the same dimensions.

The larger the take-up spool is in diameter, the less acceleration
there should be from the beginning to the end of a roll being played.
Of course, the use of a smaller diameter take-up spool would mean
greater acceleration over the length of the roll.

A roll that might play without acceleration or deceleration on one
player might not do so on another.

Hal Davis

 [ True, the take-up spool diameter for player pianos is not defined
 [ by any standard, and there is no standard published by the industry
 [ relating to acceleration.
 [
 [ The best standard I know of is the standard implied by the Ampico B,
 [ which features extremely good regulation of the take-up axle speed.
 [ The Ampico B service manual states that, when the Tempo lever is set
 [ to 87-1/2, "the take-up spool should then make exactly twelve
 [ revolutions per minute."
 [
 [ To meet this definition the diameter of the take-up spool must be
 [ 2.784 inches.  The smaller take-up spool in the Ampico A would mean
 [ more acceleration than desired, but the air-motor slows down due to
 [ the increased load as the paper transfers from the supply spool to
 [ the take-up spool.  -- Robbie