Students
Travis Vandewarker
ELE, 2019
Glenda Chen
CBE, 2020
Project Description
This project was unique in that it was a restoration rather than a new design. At the start of the project, the piano was playable, but unrestored. It showed clear signs of decades of unuse and deterioration. Most of the work done can be divided into two categories: the mechanical parts that would be present on any upright piano, and the pneumatic parts that are only present on self-playing pianos. The most immediate concern found was a few keys that stuck down after being pressed. After some inspection, it was discovered that several of the hammer return springs were pushed out of place and not working correctly. This likely happened during transportation at some point in the piano’s life. This was fixed by carefully putting the springs back into place with needlenose pliers. The piano was also tuned, but this is an ongoing process, as its condition causes it to fall out of tune in a matter of days. On the pneumatic side, the tubing for automatic actuation of the sustain pedal was found to be unhooked and taped over. This was a more involved repair. All of the missing tubing was replaced, and brass fittings that had been broken were replaced and re-glued. A new gasket had to be made and fitted for the sustain pedal bellows.
Technical Background
Player pianos were a widespread form of home entertainment in the 20th century. Still today, they are an impressive feat of engineering. When the pneumatics are off, the piano can be played manually just like a traditional upright piano, but the piano is also capable of “playing itself” using a pneumatic system to actuate the keys. The music is read from a roll of paper with holes in it to indicate the position of notes to be played.
The driving force behind the automated playing system is air suction, powered by either an electric motor or foot pedals[1]. When the lower treadles are pumped with the feet (or, in the case of the electric motor, when the suction pump is active), the exhaust bellows drive air out into the atmosphere, creating low pressure and therefore suction inside the pneumatics[2]. This lower mechanism is connected to the upper player action via a series of rubber tubes, so as to create a long, extended chamber of vacuum pressure. Leaks in the tubing are therefore the largest issue with player piano automated playing (supposing the mechanical aspects of the piano itself are intact); the vacuum pressure from the lower action sucks in air from the site of the leak rather than creating the necessary movement in the upper action.
The upper pneumatic stack has one tube for each key; when a tube is covered by the paper roll (default state) it is silent, whereas when the tube is open to the outside, the air suction lifts a small bellows membrane to depress the key, triggering the hammer to strike the strings[3].
Some pianos, including the model in the EPICS lab, have an auto-sustain bellows in the lower corner of the bottom action. The manual sustain pedal allows string vibrations to ring out for an extended period of time by lifting the row of dampers. An auto-sustain hole in the player roll codes for the same thing: the tube to the auto-sustain bellows fills the bellows with air, pushing up on a rod which pushes up the dampers in the upper action[3].
[1] Benner, Frank. “How Does a Player Piano Work?” Technical Subjects, www.pianotopics.nl/FT06v.htm.
[2] McLaughlin, Ian. “Player Piano – How It Works.” The Player Piano Page, www.pianola.com/ppworks.htm.
[3] Tuttle, John A. Technical Articles about Player Pianos, www.player-care.com/technicl.html.
