Secondary Valve Chest: Teardown

There are any number of ways I could proceed in further adventures of rebuilding this player piano action, but since we’ve been discussing valves let’s continue with the secondary valve chest.

When you are looking at the front of the stack, the secondary valve chest is the bottom compartment. More specifically what you are seeing is the back of the pouch board.

secondary valve chest overview
Secondary valve chest as seen from outside of stack

Assuming you have already removed the head, the shelf, the primary valve chest and the “L” board connector, you are now in a position to open up the secondary valve chest.

It is fairly self evident as there are many screws to undo, to peel off the pouch board.
Depending on the gasket material and potential use of adhesives, it should come off without too much resistance.

Now what you will see is something like the following:

valve board and pouch board
opening secondary valve chest: pouch board and valve board

Set the pouch board aside for the time being, I will discuss in a future post. Next, it is necessary to remove the valve board from the pneumatic decks assembly, by removing all the screws of the type that are marked with a blue asterisk. Note that there is a raised screw marked in this photo with a red asterisk, which you probably want to not mess with at this time. There may be 2 or 3 of this type.
I will take this opportunity to remind you about the value of screw maps to ensure the screws go back where they came from, when the time comes.

Once you’ve got the valve board off, it’s time to remove each individual valve – 88 of them!
Depending on how they are secured to the valve board, the technique may need variation.
In my case, they were simply screwed and had a blotter paper gasket, so just removing the screws was all it took.
In other variations of action, it is very prudent to exercise caution here: if the valves have plates as pictured, and these plates are secured or sealed with shellac or other adhesive, even if you remove the screws, the plates will resist removal and if you force them without dealing with the adhesive, you will deform the plates and ruin them.
The common approach is to use a soldering iron with the tip touching the plate, until the heat transfers to the adhesive and softens it.

Another thing to note is that there may be two sizes of screws holding down the plates, the ones holding the stem guide may be slightly longer. It will be helpful later to separate them by length as they are removed.

Once that’s all done, now what you have is this:

valves removed
removing secondary valves from valve board

Finally, you must disassemble each individual valve into its constituent parts.

I kept track of everything by putting valve parts in ice cube trays: all components of a given valve in a compartment. The tray compartments were labelled with a strip of tape on each side which was numbered accordingly. You need about six trays for the whole collection, but hey they’re cheap!

The first step of disassembly is usually to remove the wooden buttons from the bottom of each stem.
If they are on there firmly, you will need to grip the stem with forceps or another small but strong and smooth tool to avoid marring the stem.
Once the button is off, the stem guide and metal seat plate will fall off as well.

For these stem type valves, the valve facings are usually held onto the stem by small press-fit collars. These collars, if removed carefully, may be reused, so let’s try for that. There are a couple of ways to do this; I used the following set up:

removing collar
removing collar from valve stem

One hand gripping the stem with a pair of gripping pliers and a non-marring but firm substance (a slotted piece of nylon cutting board); the other hand with a pair of parallel pliers gripping the collar. Parallel pliers are much preferred to grip the collar firmly and evenly at the tip of the pliers. Twist and pull the collar off, straight out to avoid bending the stem.
You can also press the stem off the collar, as done by Bruce Newman.

Once you’ve done all that, it’s time to decide what needs to be replaced, and what you can salvage, then start the rebuilding of the valves!

valves dismantled
secondary valves during disassembly