Key bushing is a procedure that can be done as part of a regulation, reconditioning or rebuilding of a piano, but can also be done independent of any other procedure and greatly improve the touch or “feel” of the piano.
A key bushing is the bearing surface between the wood of the key and the pin which guides the vertical movement of the key. Most commonly it is felt glued inside the mortise or opening in the key where the pin is, although it may also be leather. The felt or leather will compress and/or wear over time, causing the key to have excessive lateral movement or wobble as it moves up and down with playing.
This excess wobble in the key results in a loss of control and power as the key is played, and can contribute to a “sloppy” feel to the action. Replacing the worn felt with new felt restores the touch of the piano to that new piano feel, giving the player more security and confidence in their playing. I have had pianists comment that they thought the piano had been regulated, even though key bushing replacement is all that was done.
When the key bushings are replaced, other work is often done as well, such as:
Cleaning the keys – especially the grime that accumulates on the sides at the front
Polishing and lubricating the key pins and capstan screws
Cleaning the action frame and possible replacement of other worn or damaged felt related to the keys and frame (back rail felt and key pin punchings)
Lubricating the bushings to enhance longer life and reduce friction
Sizing of the balance rail hole to ensure a solid but not-too-tight fit to the pin
Check out the photo gallery for some before and after pictures of this work being done.