Hacking the Player Piano – Part 1

 

It was only a matter of time before this happened – the player piano (original post) is a real workout to play manually. Since it works on vacuum, I had set aside the motor from an old vacuum cleaner for potential use in powering the piano. Tonight I built a small box to contain the vacuum motor and connect it to the piano. The box is made from MDF, partly because I had scrap that needed to be used, and partly because it’s very heavy & sound absorbing. I made the big fitting by cutting/milling a square from scrap, I then bored a hole in it on the lathe and welded it to a scrap of pipe.

One very large hose goes to the manifold powering all the key bellows, and another smaller hose powers the vacuum motor for the tracker/scroll mechanism. I didn’t notice the smaller connection at first, so I had to go back and tap a fitting into the connection for the large hose; there’s still enough room for both to connect though.

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Overall it seems to work great, this effort was definitely a quick proof-of-concept though and I’ll need to go back and fix/test a few things:

#1 – Motor controller to slow down the vacuum motor. Currently it has way more vacuum than is actually needed and slowing down should reduce noise from the motor.

#2 – Ensure cooling is OK. Especially after slowing the motor down I need to test that air flow is good enough to keep the motor consistently cool.

#3 – Mount in piano base and complete further noise insulation.

#4 – Tee hoses (and potentially add check valves) so that manual operation still works.

Beyond that I do have plans to eventually (could be tomorrow, could be in 5yrs) automate the player mechanism using some small pneumatic solenoids I found on ebay. These would tee off of each line from the tracker bar and when they open it would simulate a hole in the paper passing by. With this it would then be computer controlled and able to play anything. By default these are off/closed, so the paper mechanism would still work fine, in computer-controlled mode I’d just need to block off the tracker bar holes with some tape.

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Piano!

Christina has had an eye out for a piano for a while.  Interestingly the standard price for used pianos is ‘free, must be able to move’. With this in mind we were shopping on ease of moving – looking at the surroundings in the listing photos to determine where it likely was (i.e. garage vs inside) was almost as important as the piano itself. The right one popped up this week, so this weekend we took the trip to pick it up. I had a particular interest in this one also since it’s a player piano. Player pianos are one of the earliest (the earliest?) wide-spread programmable automated ‘machines’; it’s fascinating to see how these were designed to be built using mostly hand-made parts and to operate without electricity.

Moving: Pianos are the archetype of things that are difficult to move. The trick, as usual, is letting the equipment/physics do the work. At the pickup side it was already in a garage; after backing up near it I jacked the tongue of the trailer up so the ramp/bed formed an even & shallow slope. I was ready with the winch at this point, but because their driveway sloped away it actually rolled onto the trailer without needing it. To unload, I backed the trailer around the back of the house to the back door and then raised it up on jack stands until it was about even with the threshold. We then put a 4×4 timber across the bottom of door frame of a nearby interior door and used this as an anchor point to winch the piano inside with ratchet straps. Once it landed on the tile floor it was easy to push around.

Rebuild: As near as we can tell from the serial number the piano seems to have been built in 1920. It was also signed inside with a 1996 date, likely associated with a rebuild. The good news is that everything seems to be in place and after sealing a few vacuum leaks it was able to play automatically; It definitely had/has room for improvement though. I was able to make it sound noticeably cleaner by dialing in the correct ‘capstan’ height on the back of the keys. The next priority is getting the keys working more consistently; several of the keys (~40) were missing felt from their front hole. The front hole felt prevents the key from wobbling side-to-side. Several keys (~20) also had cracks where the back hole goes through the key. The back hole is where the key pivots, so these cracks allowed the keys to tilt side-to-side. Felt was added to the front holes and the cracked back hole parts were glued back in place; this resolved the loose key problems. For just a few keys (3) the cracked part is missing and I’ll need to create and glue in a repair piece. Once I’m finished rebuilding the keys I can then go through and set the key level and adjust the hammer action. Along the way I’ll also be coming up with an electric vacuum pump – pumping with the pedals is a work out!

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