Moment of Inertia of grand action parts.

[Mark Davidson]

> > I would say the
> > work already done suggests that small variations in SWR are probably of
> > more concern than small variations in key MOI.


Richard Brekne wrote:

> This point is one of those that still bothers me a bit... and tho I have
> yet to sit down and look closely enough at the posts that speak to
> reflected MOI, it seemed they were pointing in the direction of the
> SWRatio and the Dynamic <<heavyiness>> of the action were rather
> independant of one another. Perhaps I have misunderstood and will have a
> clearer picture when I get a bit of time to go through John and yours
> posts on that matter.

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.

> 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?

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.

-Mark