madelyn mrykalo wrote: > John, > Doesnt the leverage system of the action reduce the hammer's effect on > moi? So if you take the moi of the hammer /shank assembly separately > (taking it out of the chain of leverages), will it not seem as though it > has a greater effect than it really does? Vince, Well no, the MOI of the hammer and shank become magnified by the action's leverage. At least that's what the equation for reflected inertia would suggest. I made a drawing to show how this works attached to an earlier post. It is a little complicated but it makes sense if you fallow the logic of the basic principles of physics. Mark D. came up with the same thing and so far no one has disputed the equation so for now I am assuming it's right. One thing to keep in mind is that counter balancing with lead in the front of the key is a necessary step to make the action function since without them soft playing would be very difficult to control. I think of the Balance weigh as setting the lowest threshold for soft playing. If, for example, you have a BW of 38grams, the very least force needed to start to move the action is 38gm*gravity or 38gm*980cm/sec^2. Balance weight doesn't tell us anything about how the action will respond to more force than this. 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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