air system reassembly

[nutmegct]

Gentlemen - as you remember, I had to make a new cavity board (the bottom of the air chamber) and a new middle board top piece (the narrow board with air passages) to hold the reservoir middle board.

https://photos.app.goo.gl/fLcaExpL8ta9nroeA

The middle board was glued (with permanent yellow glue) to the top piece, which was glued to the cavity board; wrecked when I tried to take them apart.

When I put the assembly back together, should there be some kind of seal or gasket (rubber? leather? etc.?) between the top piece and the middle board?

Should there be some kind of seal between the top piece and the cavity board?

The five screws go down from the cavity board into the top piece, then into the middle board. I assume neither joint should be glued - just screwed together, with/without seals.

Thanks.
Tom M.

[nutmegct]

Terminology bug bites me again.

When I wrote "cavity board" I meant foundation/bellows board.

TM

[Organfella]

You are forgiven - well done! and thanks for keeping us updated.

Nico

[Rodney]

Hi Tom,

I'd use a leather gasket where they join together. Punch holes in the spots where the screws would go through the leather, to avoid it from bunching up or binding with the screws. The leather you choose can be inexpensive packing leather. Just be careful on the thickness, because if it is too thick, the keys will be higher than the key slip once you place the final parts back on. Also take into consideration the thickness of your original foundation board - if the new one is thinner then you can compensate with a thicker gasket.

Best of luck!

Rodney

[nutmegct]

Thanks Rodney. Fortunately I did manage to match the thickness of the new bellows board (birch plywood) to the original. Also matching the "height" of the edge molding using ash strips. Quite an adventure I'm having!

I'm afraid I don't know what packing leather is, but it sounds like a very thin material. I'll also need it for between the bellows board and the cavity board. Maybe thin rubber strips (1/16" thick) would substitute.

Onward!
Tom M.

[SubBase]

Pipe organ "packing leather" isn't thin. It's a split cowhide that's suede finish both sides, as such it can't be used for valves or pneumatics where the face of it has to be air tight, but as gasket it's a great place to save some money. Try to get it 0.050" to 0.065" thick. PO stuff can be very thick up to 0.10" I believe.