Robin Hufford wrote: > > In my opinion, it would be better to consider the whippen output to be > the line from the center of the whippen center to that of the jack center. > This is the point where, for much the greater part, the load of the hammer > assembly is first reacted, for lack of a better word. I don't think this > factor can be ignored without real penalty to the analysis. The shank input > and output you suggest is the same as I conceive of. However, the interaction > of the jack and the knuckle needs work which I will have to give more thought > to. > Robin, You are right, the interaction of the jack and knuckle is a little more involved than just simply measuring the parts. Here is a drawing I use to show how to measure the output of the wip and the input of the shank. The action is at half stroke for an average measurement. The pitch point movers along the line of centers as the key is depressed. A similar situation happens at the capstan/wip connection. I don't think this degree of accuracy is going to be needed for our initial forays into action kinematics. John Hartman RPT John Hartman Pianos [link redacted at request of site owner - Jul 25, 2015] Rebuilding Steinway and Mason & Hamlin Grand Pianos Since 1979 Piano Technicians Journal Journal Illustrator/Contributing Editor [link redacted at request of site owner - Jul 25, 2015]
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