Robbie Rhodes makes a good point regarding the choice of a punch
diameter for 6-holes-per-inch music rolls.  Fortunately my 6/inch
punch and die project is not to the stage where I must settle on
a punch size.  Buying the punches and reaming the die is nearly the
last step, after all the supporting hardware is made.  Comments and
recommendations on punch size are welcomed!

The main question is:  What is the largest punch size that can be
used at the original roll tempo for the worst case rolls?  As noted
following, I have control over just about all the other things that
go into making a roll.  A second question is:  How much longer can
the roll be than the original?

My basic step size is approximately 0.003 inches.  The actual number
is somewhat less, the value chosen to match any known roll step to less
than 0.001 inches error.  In the worst case the quantizing error in
replicating any original step size will be no more than 0.0015 inches,
which is probably more accurate than most original rolls were.

Dividing the roll step size by some integer (that is, multiplying the
steps/foot by some whole number) and scaling the punch file allows
finer resolution of the punch position in chaining, without affecting
the note start and stop positions.  This means that the land size [web]
between chain punches can be set over a wide range.

Roll length can be scaled without affecting the timing relation between
notes, giving control over the space between notes, though there are
limits to how much longer the roll can be made.  Tempo range and
permissible diameter of the rolls are the factors here.

My apologies for getting so technical, but all this explains why only
punch size matters.

Bob Billings