This is my method of finding the time scale length in any given Tempo
and place the tune in the desired location.

1.  Ascertain by trial and error the speed in feet per  minute of
a full roll of paper (266 feet) at "O" roll standard speed setting
(7.5 feet/minute or Tempo 75).

1.a  Mark the paper at 25-foot intervals by using a rotary tape counter
[measuring wheel].

1.b  Run through the roll again and record the time (in minutes:seconds)
when the paper passes the 25-foot marks.  Convert to feet per minute.

2.  Draw a graph using as large scale as possible.  The vertical axis is
the speed in feet/minute, the horizontal scale being in feet of paper.

3. Assume it is already decided that the ideal music tempo of the tune
in question is 100 beats per minute.  At time = 1 minute the graph shows
that 8.5 feet of paper has passed.  So 8.5 feet = 90 inches; 90" x 2
divide by 100 = 1.8 inches per bar of music.

For all other tunes on the roll, (a) ascertain the tempo required and
(b) knowing how much paper has been used.  From the graph, find the
speed of paper (S) at the given footage, which is T = S divided by B,
where T is time scale, S is speed in ft/min, and 'B' is musical bars
per minute divided into "S".

So the above is my tempo compensation for speed of paper at any given
distance.  The tune that I then perforate will be compensated for as the
roll speed builds up.

I have made six "O" rolls totaling 69 tunes, each bar length will be
made to suit the paper speed.

Steve Bentley - SB-"O" Rolls
Vancouver, British Columbia, Canada

 [ Steve says his latest "O" Roll, SB-6, is 283 feet long, which is
 [ the most paper the "O" roll take-up spool will accommodate.  See
 [ https://www.mmdigest.com/Archives/Digests/201804/2018.04.24.04.html 
 [ -- Robbie