OK guys - time to get back to the classroom.....all this levity will soon allow us to raise keys by mental thought alone. Ric B wrote: >I was kind of looking for a way of starting to plug in values easily >measured and looking at some things right away. But what you say >below would seem to make things a bit more difficult. Well, yes. It's always more difficult to measure dynamic parameters, especially with something like this for which it can't be estimated on paper. You really have to take some experimental approach to get anything but ballpark figures. >I suppose you could take an average of the mass of all keys, and an >average for all whippens and shanks, and then figure in for each of >the 88 keys the variance in hammer weight to find M for each key. I wouldn't bother trying to consider key-to-key variation at this point in the game. We need a decent value for any old key first - the back-of-the-envelope approach. >And I'd rather thought you could come up with a very good >guestimation of rk as since it is the location of the center of >mass.... which would mean the key would balance at that point. We >are correct in assuming that rk is the distance the center of mass >is from the fulcrum arent we ??? not just simply << the center of >mass >> Yes. You can always find static parameters easily. But, again, it needs to be experimental, due to the peeculiar shapes etc of he various bits being included. >But since you say you cant take Mrk2 for Ik then theres not much >point in doing either of the above, and certainly the example >numbers I solved with the other day must be seen as meaningless as >they were bassed on the asummptions I ask about below. The position of the centre of mass is needed, in order to put some numbers into the analysis we've been considering. Stephen -- Stephen Birkett Fortepianos Authentic Reproductions of 18th and 19th Century Pianos 464 Winchester Drive Waterloo, Ontario Canada N2T 1K5 tel: 519-885-2228 mailto: sbirkett[at]real.uwaterloo.ca http://real.uwaterloo.ca/~sbirkett
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