Free Reed Organ Pipes
Free-reeds are normally used in accordions. The reeds are mounted in pairs
on an aluminium plate; one reed for "air-out" and one for "air-in". Here
I am only using the "air-out" reed, so I closed the other one with a piece
of strong tape and in this way I have a spare reed, I just have to turn the
plate around.
These reeds are tuned in the factory to a tuner with A=420 Hz. But on my
organ I am using A=440 Hz and that means all the reeds are too high, about
20 cent. To lower the reeds I had to scratch with a needle or the edge of
a small file on the MIDDLE of the reed. Scratch only in a length of
about 3-4 mm, laying flat on a hard surface, little by little, very light
and carefully until the reed sounds only about 4-5 cent above the zero on
the tuner.
Method
Saw out the wood in a good length and 20 by 20 mm square. Now use the wood
to form the 0.5 mm thick cardboard (from a cornflakes box) around and in
a length of 12 cm, making all 13 resonator tubes. Cut the wood to a length
of 65 mm, drilling the holes in the ends and using a zigzag saw to make the
rectangular hole, 2 mm smaller around, comparing to the reed-plate.
Glue the nipples and the tube to the wood (see the drawing). "Glue"
the reed-plate over the rectangular hole with beeswax, using a soldering
iron and a small amount of beeswax, and moving the soldering iron very quickly
around the reed-plate. The plate must not be heated.
Now tune the pipe by moving a stopper up and down in the paper-tube in order
to find the resonance. It is possible to hear by good ears, but it can also
be seen on the tuner. It starts high and goes lower and then the tuner
turns up again. Here at the lowest point is the resonance to the actual
reed. Now you have the length of the resonator and can close the tube at
the top.
The length of the resonator for the low C is about 10 cm from middle of the
reed to the inside of the top of the resonator. High C is about
6 cm long, and all the other pipes length are in between. I have been
told that the length of the resonator is not critical, but I don't know.
Glue on one layer of newspaper around the cardboard tube to reinforce and
make the tube air-tight with thinned PVA glue. Later on, add a coat
of paint.
The rank of the "accordion" pipes sounds good but it gives a special sound,
so to say, and it is funny to have. Together with the first row of stopped
organ pipes the sound is much better, almost singing.
Gisli Olsen in Sweden
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