Fred Sturm wrote: The issue is whether these two means of reducing mass as > measured at the key have an effect at all levels of acceleration. Fred, Think about it this way; with the springs, what you put into them is what you get out. When the key comes back up after a note is played the spring is loaded. When you push the key down the energy is released. You store potential energy and you release it. It has the same effect at all dynamic levels. I think of helper springs as the same thing as balance weight except it is a negative quantity. Let's say we have an action with a wip spring. it is set up so there is a balance weight of 45 gm when the spring is not attached. When the spring is attached the balance weight goes down to 35 gm. The force that just begins to move the key will be: 45*980gm/sec^2 - 10*908gm/sec^2 After this force is applied to the key any additional force used to move the action will answer to the the inertia of the rotating parts (assuming there is no friction or other factors). 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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