Replacing Player Piano Pouches

This post is a continuation of the Milton Player Piano Series.

A dissembled player piano action showing from the top to the bottom: pneumatics, primary valves, and the leather pouches that activate them. Note the hole in the pouch at the bottom center of the photo.

A damaged leather pouch.

In my last player piano post, I described the procedure of cleaning the valves that direct the flow of air and vacuum inside the player action. This time, I am replacing several of the small leather pouches that control the valves. The leather on these pouches is pretty well protected inside the valve chest, but it is very thin and vulnerable to any debris that gets sucked into the action.

My player piano had one missing pouch and two damaged ones. I purchase my replacement pouch leather from Schaff Piano Supply. I believe that the smallest amount that you can purchase is 7 sq. feet which is enough to replace all of the pouches in the action.

In their resting state, the pouches are “deflated.” When a music roll is played, air is allowed underneath the pouch which causes is to “inflate” and push on the wooden buttons that I mentioned in my post “Cleaning Player Piano Valves”. For the pouches to inflate properly, they must be airtight and have the correct amount of “dish” or concavity.

The first thing to do is to carefully remove the old pouch with a razor blade. If you are only replacing a few pouches, be careful not to damage any their neighbors. If more than a couple are damaged or are no longer airtight, it is a good idea to remove and replace all of the pouches.

The "pouch well" can be seen after removing the leather.

Find a round object that is the same size as the old pouches. This will be your template to trace out the new pouches. I used the inside diameter of a roll of electrical tape. Trace the template onto your pouch leather and cut it out with a scissors.

Using a brush, apply a small amount of liquid hide glue to the edge of the pouch well. Wrap the glossy side of the leather around a coin and drop it into the well. It important that the matte side of the leather is against the wood, as the glossy side will not adhere as well. Use your finger to smooth the pouch leather outward and against the wood. If you are replacing all of the pouches, it can be a good idea to purchase a vacuum-operated pouch tool. This tool ensures that each pouch is given the perfect and exact same amount of dish.

A small amount of hide glue applied to the outside of the pouch well.

The new pouch leather dropped into the well.

Allow the hide glue to dry for 24 hours before testing the player action.

The pouch after smoothing the edges.

The replaced pouch.

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Cleaning Player Piano Valves

This post is a continuation of the Milton Player Piano Series.

I've been working my way through all of the valves by removing, cleaning, and resealing them.  These are the valves that translate the small openings in player piano sheet music into the striking of the appropriate strings.  Behind each valve is a small pneumatic that, when the valve is closed, the pneumatic has air in it and does not actuate any other parts.  When the valve is open, the pneumatic is exposed to suction which causes it to close and launch the hammer toward strings.

The valves are meant to be airtight, but since the valves are exposed to small particles in the air that are pulled through the player action, it is possible for the sealing surfaces to catch some dust that will cause them to no longer be airtight.  The valves only move about 1/32 of an inch between the open position and the closed position, so even the smallest interference can cause the valve to malfunction.   I have no idea when the last time this player piano was serviced, but there was plenty of air leakage in the action, so I decided to go through and clean the valves. 

 This piano actually contains a double-valve action.  Each note uses two different valves.  The second set of valves can be seen in the photo below.

In this post, I am focusing on the lower set of valves.

The first step is to remove the wooden button that is threaded onto the end of the valve stem.  I use a set of Kelly Forceps to grasp the valve stem while I unthread the button by hand.

Remove the four screws holding the faceplate and set them aside in a way that you will remember which screw belongs in which hole.

The next step is to loosen the glue that is holding the valve to the board.  I do this by heating up the faceplate with a soldering iron.  Hold the iron against each side of the faceplate for 20 seconds to heat it up enough to soften the adhesive.

In order to remove the valve withough damaging the wood behind it, I use a Park Tools Pin Spanner.  The pins fit nicely into the screwholes in the faceplate and allow me to rotate the faceplate in order to break it free from the hold of the glue.

After the glue looses its hold, carefully pull out the valve and separate the faceplate, stem, and leather disc.

Note the guide in the center of the recess.  The back end of the valve stem fits into this guide to ensure it moves smoothly.

Using an old toothbrush, gently scrub the leather disc on the valve stem, as well as the loose leather disc.  Try to remove any traces of dust or dirt.

Additionally, clean any old glue off the back of the faceplate.  A clean surface here is important for a good seal against the wood.  I use a single edge razor blade to scrape it clean.

To reseal the valve to the board, use burnt shellac.  This is simply a thickened form of shellac that you can produce by buying clear shellac from the hardware store and burning off some of the alcohol in it.  Burnt shellac is an amazing adhesive.  It sticks to almost anything and it does a great job when something needs to be airtight.  The only downside is that it can take a week or longer to fully cure, so don't use it for any last minute repairs.

Brush a layer of burnt shellac around the edge of the valve socket.

Reinsert the valve.  Make sure the valve goes in straight, and the end of the valve stem fits into the guide inside the socket.

Reinstall the screws.  Be careful not to overtighten these screws and strip out the threads in the wood.

Finally, reinstall the wooden button.

Now repeat 87 more times!

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Recovering Player Piano Reservoirs

This post is a continuation of the Milton Player Piano Series.

Inside the bottom of a player piano is a system of pedals, pumps, and reservoirs that creates the suction to operate the player mechanism.  The boards that make up one of the reservoirs in my player piano had started to delaminate and the rubberized fabric had pulled away from the board resulting in a serious air leak.  The best way to repair this is to cut and scrape the old fabric off, reglue the wood that delaminated, and recover the reservoir with new fabric.

Before cutting off the old fabric, measure the existing span of the reservoir and write this number down.  When recovering the reservoir later, I want it to end up with the same span as it originally had.

Measuring the original span of the reservoir

After writing down the span, cut away as much of the fabric as possible without cutting into the wood.  Be wary while doing this because the reservoirs contain very strong internal springs that can cause damage or injury if not handled carefully.

Excess fabric cut away

Internal reservoir spring

Remove the spring by squeezing it together and pulling it out toward the open end of the reservoir.  Once the spring is removed, the cloth hinge can also be cut and the two boards can be seperated.

Closeup of the delamination

Spread the lamination slightly by using a wedge, shim, screwdriver, etc. in order to make getting glue into the joint a bit easier.  Titebond 2 works just fine for this purpose.  Get enough glue in there to just barely squeeze out when clamped.  Wipe off the excess and allow the glue to dry.

Spreading glue

Glue drying while clamped

In order to remove the board that is still mounted to the trunk board, remove the six large screws from the front of the trunk

Six large screws to remove

The second board removed from the trunk

After both boards are free, use a sharpened paint scraper to remove the bulk of the rubberized fabric.  Then, clean the edges of the board by lightly planing them with a small block plane.  The goal is to only remove traces of cloth and glue.  Remove as little wood as possible.  Finally, go over all of the board edges with a sanding block with 80 grit paper.

Once the boards are cleaned they are ready to recovered with new rubberized cloth.  I acquire my cloth from Schaff Piano Supply.

This cloth should only be glued with hide glue (preferably hot hide glue) as it allows for an airtight bond while also being reversible for future repairs.  I've made up a small batch of hot hide glue in my glue pot for this repair.

Hot glue pot

Hide glue crystals

The first thing to do is to attach a new cloth hinge.  I use pedal webbing (also from Schaff) as the reservoir hinge.

Hinge Material

The reservoir needs both an internal and an external hinge.  Attach the internal hinge first by applying hot glue to the boards and laying the cloth hinge.  Keep the folded edge of the hinge flush with or slightly inside the edge of the boards.  Use a piece of wax paper to keep from gluing the boards together.  Clamp until the glue is dry.

Clamping the inside hinge

Move the clamps to the side edges of the boards and cut another piece of pedal webbing to size for the outside hinge.  Cover the edges of the boards in hot glue.  Do not use too much glue.  If any glue gets on the inside hinge, it will become stiff and won't function as well.

Push the hinge down onto the glue and tip the reservoir up on end, using it's own weight to clamp the new hinge.  After the glue has set, trim it with a new single-edge razor. 

Once both hinges have dried, cut another piece of pedal webbing to the length of the span distance that you measured before.  This piece will be glued across the open end of the reservoir and will work against the internal spring to hold the reservoir at the right span while it is recovered.

Internal spring reinstalled

The reservoir can now be recovered.  The most important part of this process is getting a glue seal that spans the full thickness of the board.  You will need to apply glue to the edge of the board, press the board against the cloth, and then pull the cloth back to see if you will have a good seal.  If not, add some more glue, press the board against the cloth, pull the cloth up, and check it again.

When gluing the cloth, it is important to get none of the glue inside of the reservoir.  To accomplish this, apply the glue to the edge of the boards, set them on top of the cloth and use a rocking motion on each board to squeeze the glue to the outside edge.

Glue one side first, then the open end, then the other side, and finally the hinge end.  Make sure you leave enough overlap on the hinge end for a good seal.

I like to trim the open end and the edges before gluing the hinge end.  Using a new single-edge razor blade, run it snugly along the edge of the board while pulling tightly on the loose end of the cut fabric.  You want this cut to be as clean as possible.

Glue applied to the hinge end

Let the glue dry for a day or so and then reinstall using the six large screws that were removed earlier.

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Rebuilding a Milton Player Piano

So, this will just be an introductory post that will lead to several in-depth posts in the future.  My roommate came across this Milton player piano for free on Craigslist, so we went to Algiers Point a week or two ago and picked it up.   The bellows and player mechanism are not airtight, but are in remarkably good shape compared to the rest of the piano.  In the first few pictures you can see the piano with the player mechanism (as well as most of the keys) removed.  Half of the white key ivories are missing, most of the black ebony keytops are as well.  The steel pins that hold the keys in place are very rusty.  All of the key buttons have come unglued.  My next post about this piano will likely cover replacing the keytops, re-gluing the key buttons, and replacing the key bushings of all 88 keys.

I always number the keys before removing them from the piano.  This is extremely important because every key has a unique shape that is not interchangeable with any other key.  They usually have numbers stamped into them by the manufacturer, but these are often difficult to decipher.  Better to just renumber them in pencil or marker.  Because the key buttons are unglued, I also numbered those to match the keys, in case any of them fell while I was moving things around.

When removing the keys, I keep them taped together in groups of 10-20.  In this case I taped over the key buttons to keep them in place as well.  Normally I would tape them between the buttons and the keytops.

Rusty balance rail pins. These will need to be sanded and polished before reinstalling the keys.

All of these pictures were taken after I spent probably 45 minutes cleaning several rats' nests out of this piano.  Take extra care when working with a piano that has had rodents in it, as their feces can carry diseases that are transmissible to humans.  Wear a surgical mask and gloves.

Front rail pins also need sanding and polishing. The red pieces of felt are key bushings that fell out when I removed the keys.

The piano action itself is not in too bad of shape.  The hammers are worn and some have been chewed by rodents and/or come unglued.

Rodents love chewing on piano hammers.

This picture of the treble end of the action shows some previous work done. Notice the lighter replacement hammer butts as well as their green bridle straps, while the originals are red.

Player pianos rely on suction created by the pumping of two pedals to operate the pneumatics that control the piano.  The previous picture shows a hole in the reservoir component of the bellows.  If the whole system isn't airtight, the player mechanism will not work correctly, if at all.

The bellows removed from the piano. Notice the two foot pedals that used to power the player mechanism. They swing out away from the bellows when they need to be used.

The next couple pictures show what is known as the "top stack".  This includes the tracker bar which "reads" the music rolls as well as a series of valves and pneumatics that translate suction into a push on the hammer of a specific note.  Also included is the wind motor which controls the movement of the music roll across the tracker bar.

88 sets of tubes,valves, and pneumatics. One for each key.

The wind motor.

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