More than a decade ago, Gene Gerety designed and built the laser cutter
that is being used at Valley Forge Music Roll Company in Pennsylvania.
Gene's design has worked very well.  Some lessons learned during this
development that people could benefit from include:

1) Never, ever, ever laser-cut multiple layers of paper.  It is quite
tempting to cut multiple copies like with a mechanical perforator.
The fumes and paper dust are quite flammable and accumulate between
the layers of paper.  As a result, occasional use of a fire
extinguisher is called for if multiple layers are present.

2) Air flow is important to keep the flammable material from
accumulating, even with single layers of paper.  Air flow is more
effective with a single layer of paper.

3) Gene chose to cut rolls a panel at a time rather than going across
the paper a raster line at a time.  The result is much quicker but
requires more fancy programming.  This was not a problem for Gene since
he is so adept at programming.

4) Start with paper wider than the final size and cut the edges with
the laser, which keeps the punched pattern accurately located relative
to the edges.

5) The most difficult part of the project was the paper transport
system.  Gene chose to place the paper transport outside of the more
or less standard laser cutting machine.  Accurate transport metering
and alignment was critical in part because of the choice to panelize
rather than rasterize.  Paper supply and take up axes need to be very
parallel to achieve good paper tracking, so the supply and take up
should be mounted on a common frame to minimize tolerances.

6) The laser initialize function needs to be tied to the transport
system regardless of whether raster or panel mode is chosen.  If raster
is chosen, the decision needs to be made about whether each pass is the
length of the laser beam or a series of drawn circles like the punch
holes in a traditional roll perforated by mechanical punches.  The
laser needs to be done cutting before the paper advances and the paper
must be finished moving before the laser starts cutting.

There are many more lessons learned.  These are just a few I remember
from discussions with Gene while he was developing the perforator.

Jack Breen
Southborough, Massachusetts