Anatomy of a WurliTzer Theatre Pipe Organ
More Offset Chests
Next was the 12-note String + 2 Trumpet offset chest and then the 12-note 8’ Flute and
the 12-note 8’ Tibia offsets. These also took about 80 hours each to complete.
The Flute and Tibia offsets were the first chest done that use the brass inserts for the
bottom board screws. Even though these chest were generally in very good condition
and there was no sign of leakage on the gaskets many of the inserts were pulling out.
There are several options to fixing these. You can “glue” them back in place. This
works sometimes. You can buy replacement inserts from at least two of the most
well known parts suppliers. I have used replacement inserts from one supplier before.
These inserts use a different screw size so it makes life more complicated when
some inserts on a chest are replaced and others are not because you have to sort out
which screws go where. I would generally be replacing all the inserts on a chest
anyway so that is not such a problem however I would rather use the original size
screws if possible. These inserts seem to be shorter than they could be and I have
known them to pull out again which may not happen if they were longer. They also
lack any locking facility like the slot found down the side of the original inserts
which accepts a pin which is intended to stop them from unscrewing. Drilling
these replacements to accept a pin does seem to help.
The replacements from the other source are also shorter than they could be.
These do use the original screw size but are steel instead of
brass. After waiting for some custom insert to be made, which never happened, I obtained
some of these inserts. They also come without a locking system so I drilled a small
hole through each to accept a pin to prevent them unscrewing when the screws were being
removed again. Unfortunately I discovered more than half of them would not allow the
screws to go all the way through. After running a tap, the same size as they were supposed to be,
through them the original screws fitted correctly. The supplier checked their stock
and could not find the fault so it appears I was just unlucky.
While reassembling the Flute offset I checked the movement of the pallets and noticed
that they were moving more than they should so that the springs were striking the
underside of the pallets before the pneumatics and the pallet arms were hitting the
felt stops. In this case I had left the original felt in place as it was in "as new" condition,
and I did not have any the same thickness to replace it with. The pallet arms had
not been bent to a new angle so I knew I had not changed the geometry of the action.
The only conclusion seemed to be that this chest had always worked like that. I added
an extra ¼” of felt to the buffer rail and got the movement reduced just enough to
prevent the springs and the pallets from hitting. The amount of movement is probably
still more than is necessary but at least it will stop the noise of the springs hitting and
there will be no doubt about whether the pallets are opening wide enough.
Although most Wurlitzer components were massed produced it appears that you should not
assume they always left the factory exactly as the designer hoped. Returning parts to
exactly the original condition may not always produce the perfect result so it is sometimes
better to make corrections to fix any manufacturing slips, but not to try and improve the
original design.
By this stage I had five of the six pipe chests rebuilt. That only left the five rank main
Manual Chest to go but that was still not easy to get at so I changed direction and started on
some of the traps and percussions.
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