Moment of Inertia of grand action parts.

[Richard Brekne]

Mark Davidson wrote:
> 
> 
> 
> Well, the BW can be set up independently of the reflected MOI, if that's
> what you mean.  But consider that the weight ratio is based on the 6 lever
> arms in the action, while the reflected MOI is based on 4 of those six lever
> arms.  The angular speed ratio plus those last 2 lever arms gives you the
> weight ratio.

Yes, this much has been clear for some time.. essentially for the same
reasons that several different ways of placing leads in keys can arrive
at the same FW, but yeild differing MOI


> 
> > Yet anyone who has done more then a few actions with precisely alligned
> > Front weights would probably report that this same even key to key curve
> > of FW's based on consistant lead patterns is instantly appreciated by
> > the pianist.
> 
> Yes, well, but, ummm... did you smooth out the SWs at the same time??  If
> so, did you let the pianist try out the piano between smoothing the SWs and
> smoothing the FWs?  And if so, weren't the BWs out of whack since you hadn't
> smoothed the FWs yet? Would smooth BWs feel as good or better than smooth
> FWs? Did you attempt to smooth out SWR also?  If you do all of these things
> and then give the piano back, then of course they will like it better, but
> how do know which of the things you did is the reason for their liking it
> better?
> 

I've done it both ways. Even SW's are indeed noticed independantly...
but if you have FW's that are less then fairly even... despite dead on
SW's.. they will comment that the piano feels uneven. Correct the FW's
and bingo !! Ok.. this is based on 12 sample pianos, and perhaps 50
pianists... but it seems convincing enough to go with for the present. 

> 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.
> 

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 :)

> -Mark
> 
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