Problems with Stiffer Paper
In the lid of your busker organ there are two rollers that are designed to
keep the angle of paper entry and exit constant during the roll. In
the two organs I have built I assumed these were to keep the paper down against
the top of the tracker bar. So I made them low, well down below the top so
that the paper would curve nicely over it.
While this works well with thin supple paper I have encountered a problem
with the plastic paper music rolls. While these are tougher and longer lasting
they are not as supple. I found that when I played music with these
rolls I had a background noise which was all the pipes slightly blowing.
When I put down the clutch and stopped the roll moving, the paper settled
down onto the tracker bar and the noise stopped.
I found that the cause of this problem was that my rollers were too low down
and the paper was sort of bowing up as it crossed the tracker bar. The
curvature of the paper no longer matching that of the tracker bar. This
caused a slight leak of air under the paper and into all the pipes. The
air pressure alone should be enough to to keep the paper down. So if
you find you have this problem, or wish to avoid it, be careful of how these
rollers keep the paper down.
(I found that these rollers caused all sorts of problems,
and were not even needed! So I omitted them completely - MW.
The illustration below shows the thinner paper being held down by the rollers(A);
and (B) shows the effect this has on the stiffer plastic paper.