Moment of Inertia of grand action parts.

[Mark Davidson]

Robin Hufford wrote:

>The formula becomes(using I(est)) to indicate
>rotation at the balance rail,
>I(est) = 1/12ml^2 + md^2

If I understand you correctly, d is basically half the height of the key.
I.e., you're rotating the key not around its center top-to-bottom, but
around its bottom, so the center is displaced by the distance of half the
key height.  If so, for a 20 inch key that is 1 inch high this represents
only a 0.75% difference from using (1/12 ml^2) alone.  In the land of rough
estimates, I would probably not make too much of this.

-Mark