I don't think that rolls which are not exactly the same hole to hole,
also when they have the same number, are made from different master rolls.
I think it is a question of the influence of the environment. The rolls
are the same but because the size of the paper is not the same anymore
they are "different". Everybody can check it himself, just take some
different rolls of the same system and measure how wide they are and
you will see that they are mostly different, especially when they were
stored at different places (better different collections/countries).
In my opinion it is most important that you take care of the following
when you copy rolls:
- The position of the hole in relation to the other holes, which means
which holes will be read by the trackerbar together.
- The size of the hole.
- The right scale, so that each roll will fit exactly with the hole in
- The right measurement of the paper.
In our machine we use Motors which measure "direct", which means not
step by step. In the length we accept a difference of 1 mm at the Meter
(0,001 %). We take the original length because we have no better
information. But the scale we adjust at the trackerbar because these
is the point were the holes have to be read, so it is not a hole to hole
copy from the scale , but I place the assertion that the rolls we have
now are not exactly like they were in the 1920th.. To make a hole to hole
copy today will be the same then to make a new Piano which is in each
detail (condition of the hammers etc.) the same then the original
unrestored of 1920.
Greetings from the romantic part of the Rhine.