First of all is this on a particular model and brand of piano and how old are the pianos ? Have you traced where the sound seems to come from and at what point in the travel ? it sounds like it is at both ends of the key frame travel . I am thinking the felt stop inside the action cavity could be the source. I have seen that worn down so far it is like a piece of veneer and useless as a sound reducer. Other issues could be the position of the shift mechanism in the keybed slot or even contact underside the keybed where the lever is position. On some pianos the spacing is very tight and there is contact with the trapwork levers. I would try to break the problem down into manageable pieces and try to correct the sound on one side. Often times sounds throw you off because they get transmitted and amplified or they have multiple layers.
Perhaps its time to explore using things such as acoustic foams, hard rubber blocks and other noise reduction methods. The appliance industry has learned to reduce the noise of dishwashers, washer machines, dryers by using rubber grommets, foams and blocks between components. I replaced the food grinder in my sink with one that had a rubber gasket flange that isolated it from the metal sink. Huge noise reduction.
BTW the sound can also becoming from the sudden pedal release and starting in the pedal box or a loose lyre and lyre brace
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James Kelly
Owner- Fur Elise Piano Service
Pawleys Island SC
843-325-4357
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Original Message:
Sent: 11-08-2021 10:04
From: Floyd Gadd
Subject: Shift Clunk
I am paying closer attention to the shift mechanisms on our collection of university pianos, and am noting various squeaks, whooshes, clicks and clunks. I have found some very helpful journal articles (using the preliminary index produced by Fred and Jeannie) regarding the hunting down and solving of issues arising from friction, but nothing addressing the percussive clunk that sometimes occurs at either end of travel of the key frame. One suggestion from Roger Gable, concerning installing a capstan under the keybed to limit shift lever travel (to be adjusted to reinforce the function of the stop screw that meets the end of the keyframe) might help at the right end of keyframe travel, but what suggestions do you have to mitigate a loud clunk that occurs on the sudden release of the shft pedal? Other than instructing the pianists to pedal more intelligently . . . Not that anyone has been complaining.
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Floyd Gadd
Regina SK
306-502-9103
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