Interesting. When this thread was taking place, I thought about some older pianos I tune. One came to mind of a customer near here. The keysticks are "tied" to the action by stickers. At the bottom, the stickers are bifurcated like a split wedge, and they each clip over a centre pin mounted in a flange thingy on the end of the keystick. At the top, each sticker is fastened to the underside of the wippen by a mounting with an ordinary type centre and centre pin. The rocking/rolling action of such an arrangement must be quite different from modern pianos with capstan/wipeen arrangements like those being discussed. Even though wippens when new have undersides offering a convex arc to meet the smaller-radius convex arc of the capstan top, it doesnlt take long for the cloth surface of the wippen underside to wear to a different shape, such that in time convex capstan bears on convex wippen. Sorry, this has probably all been said! David.
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