Do Not Fit
the Paper Tension Rollers - They are not needed and can cause
problems.
The beauty of an organ operated by a vacuum underneath the music roll, or
by pressure from above the music roll, is that it doesn't need any contrivance
to hold the paper down onto the tracker bar. The air pressure does
all the work. In fact, many paper roll organs (and pianos) are deliberately
designed at extra cost to take advantage of this feature. They either use
a separate vacuum supply to read the music, or they have the roll mounted
in a pressure box. Now, the John Smith design already uses a pressure
box because of the way it works, so it seems bizarre that it should also
need to be fitted with rollers to hold the paper down onto the tracker bar!
So I removed these rollers and (as expected) found them to be completely
unnecessary. I found that the air pressure is more than enough to keep
the paper pressed down onto the tracker bar, and the organ plays perfectly
without them, and there are no leaks. I don't really understand why
these rollers are mentioned in the plans at all.
The paper on the supply side of the tracker bar is always below the level
of the tracker bar anyway, so it doesn't need a roller to hold it down.
The paper on the take-up side does rise almost to the level of the
tracker bar at the end of a long roll, but I found it was not enough to cause
any leaks.
These rollers are unsightly, noisy, spoil the view of the music through the
window, and could cause tracking problems and damage to paper music if they
are not aligned accurately. They also increase the paper friction
considerably, which can lead to slippage and stalling of the music.
So my advice would be to leave these rollers out until the organ is finished,
and then decide whether they are needed or not. If you find that they
are needed, it is far preferable, and easier, to raise the level of
the tracker bar instead of installing these ugly, and cumbersome rollers.
This can easily be done by adding a spacer block underneath it to raise
it up a few mm. Although I found that even this was not necessary.
I just removed the rollers and carried on playing!
I would be interested in hearing if anybody has removed (or not fitted) these
rollers, and found them to be necessary.
"Hi Melvyn, When out recently on a very cold day with my John Smith Universal,
the music kept sticking, I took out the 2 tension bars from the pressure
box, and from then on I had no problems. I will probably leave them out now
after seeing your advice on your website - DC" |
