Moment of Inertia of grand action parts.

[Bill Ballard]

At 1:58 AM +0100 12/29/03, Richard Brekne wrote:
>Yes... thats true enough. But one thing at a time as it were. It seems
>reasonable to first figure the velocity of the hammer for key velocity
>as if it were in total compliance, then figure a compliance value, then
>find that combination of inertia, mass, leverage, whathaveyou that sees
>the maximum amount of hammer velocity for key velocity coincide best
>with the saturation point of the action. Yes ?

Clearly there's no sense in pouring further energy into the action 
after you've overcome its ability to absorb your energy. It sounds as 
though we're going to tune action leverage, so as to carry the weight 
hammer we want without either counterbalancing the action so much as 
to slow it up, or so badly unbalanced that the force of our attack 
will allow the flexibility of parts to waylay energy.

If we're worrying about lowering the maximum amount of energy the 
action can absorb due to the leveraged weight of parts and consequent 
counterbalancing, there's another point where energy is transferred 
from one system to another, and where saturation is also to be 
avoided. That's between the hammer and the string. The last thing we 
need here is for energy to be wasted during the transfer of energy at 
the collision of hammer and string. (Yes, heavy and hard hammers do 
block the strings in high force situations.)

It would be nice if the weight of the hammer could be mated to the 
strings' ability to absorb its impact. Then success at mating the 
action leverage, weight and counterbalancing could occur in 
conjunction with it. That would be a well designed piano.

Bill Ballard RPT
NH Chapter, P.T.G.

"No one builds the *perfect* piano, you can only remove the obstacles 
to that perfection during the building."
     ...........LaRoy Edwards, Yamaha International Corp
+++++++++++++++++++++