The key ratio has in it self nothing to do with the contact point between levers. Neither does the whippen per se. It's just that this contact point defines the exact point of input (or output depending on how you look at it) to both levers. It is the distance this point is from the fulcrum, and the distance the opposite side input (output) is from the fulcrum that defines the key ratio. Phils lead coil explaination simply said that if you put a ten gram weight on the top of an angled capstan it will yeild a different Key Ratio reading (FW too for that matter) then if you placed that same 10 gram weight directly above the hole where the capstan goes into the key. No point making this more difficult then it is. Cheers RicB David Love wrote: If I understand Phil's explanation (and my small experiment), the KR is a function of the combination of the contact point with the key and contact point of the top of the capstan with the wippen heal. On a straight up capstan there is not difference. If the capstan is angled back at a 45o angle, the KR as measured from the very top of the capstan will not be equal to the KR as measured from a point on the key directly below the point of contact with the wippen heal. It will be something between the contact point with the key and the point directly below the contact point with the wippen heal. Therefore, angling the capstan does lower the ratio (assuming the the same contact point on the wippen), you just don't get the full benefit of the new position vis a vis the contact point with the key. But maybe someone can provide the math. David Love davidlovepianos@comcast.net <mailto:davidlovepianos@comcast.net>
This PTG archive page provided courtesy of Moy Piano Service, LLC