Re: Accuracy of Recut Music Rolls

I don't know where I got the idea that the stepping rate of the master
roll on the perforator reader traveled faster than the copy would.  Is
this how they got better accuracy than if they had the master and copy
paper rates the same?  Is this how they accurately punch the chains on
the rolls?

I would also expect that the master rolls used on the perforators would
have been modified so that the holes on the copy wouldn't be punched to
early.  An example of this would be that when a hole in the master is
partially opened at the tracker bar, when should the punch be made on
the copy.  This could punch a hole about 1/2 of a hole earlier than it
would appear on the master paper. Making copies of a copy will cause
the punched holes to grow progressively longer.  I am sure that some
one who makes rolls would take this into account when making copies of
rolls, but maybe not.

If the above is true, does this mean that if a master roll used for
making duplicates on a perforator is played on a player piano, the
timing might be off and not play properly?  I am primarily thinking
about recut rolls for the Welte-Mignon system because the timing is so
very critical for this player.  I have found big differences between
original and recut Welte rolls.

I am also thinking about these types of issues with the optical
scanners that are being developed by the www.IAMMP.org group.  They are
developing a scanner using 300 DPI technology that is more accurate than
any of the old pneumatic systems are capable of.  What the scanner
reads is what can be duplicated.  You will know exactly where the edge
of the hole starts and ends on the roll that is being read.  I don't
know what the chosen vertical resolution is but it will be less than
300 DPI.  The source of the rolls being scanned might determine how the
data should be interpreted.  Was the roll being scanned a master
perforator roll, a copy from the master, or even a 3rd generation roll,
and who made the copy of the roll?

Does the stretching of the holes affect the music?  Yes it does.  Should
the source of the rolls be questioned?  Yes, they should.

Pete Knobloch (Tempe, AZ)

 [ The master roll is 2 or 3 times the length of the production roll,
 [ thus overlapping holes in the production roll are nicely separated
 [ round holes in the master.  The master roll is extra wide, with
 [ sprocket holes in each edge, and it's driven by a sprocket wheel
 [ coupled to the crankshaft.  This ensures that every hole in the
 [ master roll is properly centered over the hole in its tracker bar.
 [
 [ The data of the master roll is synchronized because each revolution
 [ of the crankshaft advances the master roll exactly to read the next
 [ row of holes.  Each hole in the master roll results in exactly one
 [ hole punched in the copy.  Every copy produced with this process is
 [ identical, even if another production run is several years later.
 [ This synchronous perforating process results in hole-for-hole
 [ replication of the master roll data.
 [
 [ See the photos of the restored Wurlitzer perforator and master rolls
 [ at Matthew Caulfield's site, http://wurlitzer-rolls.com/pdetails.html
 [ At each end of the shiny drum to the left of the big hand wheel is
 [ a pinned sprocket wheel which keeps the master roll synchronized with
 [ the perforator crankshaft.  Note the resemblance of the Wurlitzer
 [ master rolls to European carton (cardboard) book music, since the
 [ reader is mechanical instead of pneumatic.  -- Robbie