Moment of Inertia of grand action parts.

Mark Davidson mark.davidson@mindspring.com
Sun, 4 Jan 2004 12:18:54 -0500


>> That said, I can see reasons why smooth FWs might feel better.  If you
have
>> very even key inertia, then you can really feel the hammer's inertia.
This
>> could give a better sense of control, perhaps.
>
>RicB wrote:
>
>Interesting thought... sort of a back door way of re-introducing the
>importance of the keys MOI...despite its small value relative to the
>hammer ? Explain your thinking a bit more in detail please :)

Well, the pianist is getting feedback from fingers and ears.  So if a note
is harder to play but doesn't generate more sound as a result, it will be
sensed as unevenness.  This is what happens in the case of uneven FWs or
BWs.  But suppose the FW was perfectly smooth, the SWs are smooth but there
is still some variation in SWR (which there is likely to be).  Then there
will still be some unevenness in the reflected inertia of the hammers, but
the feedback from finger and ear will be better correlated.  A hammer being
accelerated faster (higher SWR) will feel heavier, which it ought to. The
same force will result in less acceleration, but for a longer time, which
works out to the same final energy in the hammer.  But you can only get
there if you can eliminate the "noise" of uneven key inertia and BW.

-Mark


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