What Bob Billings states might need to qualified a bit.

I believe he is assuming that one is dealing only with standard-
size player piano rolls when he speaks of the densities of the
perforations.

Having built four perforators over the years and having some
experience therewith, I feel that I can add something to his comments.
What he says is correct for the situation where he is dealing, as I
said with regular player piano rolls or rolls of similar length.

In actual practice, when dealing with multi-tune rolls, the
perforation density changes several times through the length of the
roll when.  Often a ten tune roll for example will use one spacing for
the first three tunes, another spacing for the next three and yet
another for the last four tunes.  There is also the factor of how the
sheet being perforated is being fed through the perforator.

Another factor that interacts with that is the actual thickness of the
material being perforated, if the feed system is other than a parallel
chain-feed type.  That also can be altered by using more or fewer
copies of the roll at the same time.  Again this is an effect if other
than a parallel chain-feed system is used.  Most of the other
perforators that I have seen did not use the chain-feed system so
would be subject to the various effects.

 [ John Malone uses this type of paper-puller for the high-speed
 [ perforator at Play-Rite.  It was developed, I believe, for the
 [ textile industry.  The multiple clamps attached to the chain-drive
 [ grab the layers of cloth (or paper) very securely, thus all the sheets
 [ in the "web" are trimmed or punched equally.  With a capstan-roller
 [ system it's possible for the slick paper to slip unpredictably during
 [ perforating.  -- Robbie

Typical perforation densities on player piano rolls ran from as low as
16 to the inch to as many as 26 to the inch, and I suppose there were
some others than exceeded this range but they would have been rare.
Although there were some rolls perforated entirely with chain perfora-
tions rather than with the 'elongated' perforations we know so well.

Yes, punch size can make a difference as well but normally it's not
a big deal.  The important thing to remember about that is the ratio
of perforation diameter to bleed hole diameter in the individual
piano.  Most, but not all, pianos used pretty much the same or similar
sized bleeds so it wasn't a problem of concern, but for the 'absolute
purist' it could cost them a nights sleep, I suppose.

Personally, I just like to lean back and enjoy the positive things
that are happening in life, and if the piano plays and sounds good
then great.  My wife and kids aren't perfect and I don't have a
problem with that so why am I going to have a problem with a piano?

Musically yours

Hal Davis