Why I Like Balance Weights (was:Ham vs Am S&S)

[stanwood]

Bob Davis writes:

>had pianists like a 70-gram (!) low inertia keyboard better than a 50-gram
>high-inertia one

Yes, but try playing pianissimo glissando with a 70 gram downwt.

>For the mass, one can measure the hammer head alone, or the hammer head and
>shank assembly pivoted at the flange pin (a la Stanwood). The head weight is
>the most important because it is so far away from the pivot. David's method
>is more accurate on an absolute basis, but it's still instructive to measure
>heads if they're off the shanks

Strike Weight is generally around 2.0 grams higher than hammer weight.

>If we know the leverage and the hammer mass, the mass of the front of the key
>is implicit in a wippen-spring-less system  (I know, there's the wippen and
>shank, but we can almost ignore them as constants), and we have enough
>information to judge the relative inertia. For a quick assessment either of a
>problem action or of one due an overhaul, I weigh at least A0, C4, and C8
>(pivoted on their shanks), and dip vs blow. It takes just a few minutes and
>gives me a pretty good idea of where I'm headed. If the friction is high, I
>also check one set of parts for proper pinning, and if it is okay but the
>friction is still high, I check for rubbing friction due to bad geometry.

Bob is setting a good example for us all by working to adopt methodology
that pays attention to weight, leverage, and friction.

David C. Stanwood

http://www.tiac.net/users/stanwood/st&co.htm