Key Leads and Inertia

[Classic Touch Ent]

Greetings Del,
       Thanks for resurrecting key bend energy loss as an issue. Is it 
primarily energy lost or does it amount to energy delayed? Both? Is the 
'delay' sufficient to amount to 'loss"? How quickly does the key 
'remember' it s original shape? There's certainly an interesting 
difference in the timing  and efficiency of the transmission of energy 
in a slow velocity key blow vs. max velocity blow. How much does a key 
stick bend at full blow with 'no stack/no lead'? If we work to stiffen 
a key I suspect new challenges in the way of action 
fragility/durability will arise. As a pianist it has not escaped my 
notice that I don't always get a bigger/louder sound from maximum 
acceleration of my paw vs. say 'dropping' my paw from 6-12" above the 
keys.
      It seems that at least part of the result of trying to wring more 
and more power/amplitude? from the piano-forte is that we create 
greater inefficiency at least partly because traditional 
materials/designs are driven past their limits of efficiency. Bigger 
hammers (and shanks?) to drive the heaviest of the linear springs, 
increased string/spring tension, greater mass stacks (and greater mass 
balance weights) all conspire to stretch the limits of material and 
design.
      Ver-r-r-y interestingk!

Best, Rich Olmsted
On Tuesday, April 29, 2003, at 02:52 AM, Delwin D. Fandrich wrote:

>
> ----- Original Message -----
> From: "Sarah Fox" <sarah@gendernet.org>
> To: <oleg-i@wanadoo.fr>; "Pianotech" <pianotech@ptg.org>
> Sent: Monday, April 28, 2003 2:53 PM
> Subject: Re: Key Leads and Inertia
>
>
>> Hi all,
>>
>> Isaac wrote:
>>> Nowadays lead being a necessity, seems primordial to conceive the 
>>> most
>>> optimum match between the strings, soundboard system+ &  the hammers
>>> to avoid unnecessary balancing .
>>
>> Could springs not be employed instead of weights?  Lower inertia would
> mean
>> that more of the energy from the pianist's hand could be transferred 
>> into
>> kinetic energy of the hammer, rather than dissipated in the form of 
>> heat
>> when a more massive key bangs into the front rail punching.  Also, 
>> springs
>> can move very quickly (faster than gravitational acceleration), so the
>> system would be balanced and more responsive over a large dynamic 
>> range
>> (therefore still assisting, rather than hindering, during ff 
>> passages).
>> Piano actions are quite evolved, true, but it seems they have so far 
>> yet
> to
>> go.
>
>
> Most of the energy lost between the key end and the hammer goes into 
> bending
> the key. At action saturation the front of the key fully bottoms 
> before the
> hammer starts to move. I'm not sure how much key leading contributes 
> to this
> but I shouldn't think it was all that much.
>
> Del
>
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