Soundboard stiffness variances

[David Love]

The problem is that each panel's compression characteristics will be
different or, you could say, have its own distinct personality.  Not only in
terms of how much compression they will take at the outset which will
determine how much crown will form initially, but how well it will withstand
the compression in the short and long term.  Some panels change quite a bit
from the factory to the showroom floor and almost all of them change within
the first year or two.  In an environment with large humidity swings they
will change even more.  I don't know how you would be able to predict that
with any degree of accuracy.  If one insisted on having compression in the
panel then the best way is probably a hybrid system where you underbuild the
precrowned rib support somewhat counting on a certain amount, but less,
compression to achieve the rest of the requisite stiffness.  You still have
the unpredictability of the panel's unique ability to withstand compression,
but reducing the amount might create a somewhat more stable system. 

David Love
davidlovepianos at comcast.net
www.davidlovepianos.com 

-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Jude Reveley/Absolute Piano
Sent: Monday, February 11, 2008 6:05 AM
To: Pianotech List
Subject: Re: Soundboard stiffness variances

 

 

 

> The problem, as has been outlined many times, is not that the RC&S people
> aren't interested in the predictability of the CC system, it's that the CC
> system is by its nature unpredictable both in terms of the initial outcome
> and the long (or short) term prognosis and sustainability.     
> 
> David Love
>  <mailto:davidlovepianos at comcast.net> davidlovepianos at comcast.net 
>  <http://www.davidlovepianos.com> www.davidlovepianos.com

 

Well put, David. My instinct and experience would lead me to agree. It would
sort of be like measuring Heisenberg's particle in that the very stiffness
we would try to measure is always changing, just by our very breath as we
lean over the thing to examine it. 

 

Jude Reveley, RPT
Absolute Piano Restoration, LLC
Lowell, Massachusetts
(978) 323-4545

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