Gluing Pneumatics + Testing (Round 3)

Your finished pneumatics have been tested, and are standing by — in order — to be remounted.
You have a large pot of medium thick hot hide glue at the ready, with brushes, wet and dry cloths, etc.
The temperature of the workspace should be as warm as possible; a nice humid summer day with the windows open is ideal, to give the glue as much “open” time as you can.
Give a final inspection to your decks, confirming that damage has been repaired, and that all your scribe lines are clear for easy location of the pneumatics. The stage is set!
Gluing down pneumatics doesn’t need to be stressful, since hide glue is water soluble and therefore reversible.
Having said that, your first attempt should be your best, since it does involve some work to get back to ideal gluing conditions.
Once again, Bruce Newman to the rescue!

I would simply add that it may be better to leave a slight ring of bare wood around the hole of the stationary board, to avoid getting too much glue into the supply port. This tip came to me from John Tuttle.

If you have good glue, and you move quickly to place the pneumatic exactly where it needs to go, you should have success. Some rebuilders advocate for using clamps, but really hot hide glue will set up to be self-clamping for this application, so in my opinion it’s overkill. If you see a nice little bead of squeeze out around the perimeter of the board, that is a good visual confirmation that you have likely been successful.

As Bruce demonstrates in his video, you can test as you go (or after) by blocking each port completely then trying to open the pneumatic to check the seal. If you had previously resealed all the deck channels, and you also tested your pneumatics, then everything should be well.
On the off chance that there is a small leak, visually inspect to see if there is an interruption in the glue bead. Take a listen for any slight hissing indicating a leak, and if so carefully apply a bit more glue or sealer to take care of it, without touching the cloth!

There are some odds and ends to finish up the decks. If there is a rest rail for the fingers, reinstall it now (after testing), and put down some new cloth which matches the old. After your fingers have been repaired or rebuilt as necessary, and the pushrods are clean and polished, it’s time to put them back. First install the upper leather nuts on the rods. I used a slotted piece of plastic cutting board as a kind of “stop guide” to rough in the position of these nuts. Attach the rods to the fingers (if necessary), insert a cloth washer (if needed) then carefully reintroduce them onto the metal hangers or fingers of the pneumatics.

Returning finger rest rail to the pneumatic deck
a piece of plastic cutting board makes an ad hoc stop jig for approximating the position of the upper leather nut

Careful is very much the watchword here, as it is imperative to not damage your pneumatic cloth at this point – doing so will throw cold water on the great progress that has been made!

Using your fingers (the extremely cautions approach) or the leather nut driving tool (the somewhat less cautious approach), thread each leather nut (with cloth washer) onto its rod.
If ever you slip and scratch the cloth, breaking the air seal, it may be possible to repair a pinhole such as this with diluted PCVE or similar flexible sealant. With diligent work it should not be necessary.

replacing the push rods onto the pneumatic hangers

The last details, if not yet attended to, are the edge gaskets for the decks, and possibly for the mounting blocks for the primary chest (if present).
In fact the measuring and cutting for these gaskets is more easily done before the pneumatics have been remounted, but the application of the gaskets should come last, since they are rendered effectively useless if there is glue or sealant leaked onto the working face.

punching gaskets for the edge of the pneumatic decks

With this done, we now see the light at the end of the tunnel.
Let’s do some regulation!

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