Soundboard stiffness variances

[Richard Brekne]

Well yours is certainly one perspective among many out there. And tho 
numbers of CR enthusiasts out there greatly outnumber you... you are 
certainly not alone. And to be truthful... I for one am glad there are 
as large a variety in perspectives on the matter as you imply are 
inherent ly present in CR boards.

The variety of sound pallets in Steinway's is an intentional result.  
That they purposefully do not take into account the variabilities with 
intent to normalize them in no way means such normalization is not a 
doable.  I'd surmise that since much of the industry plays follow the 
leader in so many other ways... they rather buy into Steinway's 
reasoning a long way down this road as well. In fact... the whole 
purpose of RC&S design is essentially a kind of normalization process in 
the sense that it seeks to simply by-pass the problem.  How much of the 
problem is actually by-passed is another matter.  Still... none of this 
has any bearing on whether or not one can indeed predict CR system 
strengths or not.  Just as one can test ribs... there are ways of 
testing flitches before assembly into a panel. Or for that matter wood 
stock before cutting into flitches.  Quick and dirty... but usable ..??  
float it.  The degree of the wood above the water line represents 
exactly the specific gravity of the piece of wood.

Cheers
RicB



    The piano world is replete with living (and dead) examples of the
    unpredictability of the compression crowning method.  Anyone who has
    paid
    attention has heard the evidence.  NY Steinway pianos are a great
    source for
    this study especially if you take the "different personalities"
    euphemism as
    a statement to the effect that each piece of wood will respond
    differently
    to their own particular method.  This is not to be read as a
    criticism of
    their choice, necessarily.  It is their choice and there are
    examples where
    it's produced a very musical outcome.  

    While variations in rib strength do occur they can be easily tested
    prior to
    gluing them up as some rebuilders do.  The purpose of the laminated
    rib is
    also to create a more uniform MOE from rib to rib by mixing lots.  

    I don't want to discourage anyone, though.  I will be on the sidelines
    cheering anyone who wants to embark on a scientific study to prove
    the true
    limited variability of the compression of spruce in the compression
    crowning
    method.  You will need a skilled grant writer though as the costs
    will be
    high, too high for me and, unfortunately, I'm not in a position to
    donate
    any money to the cause--at least not until the kids are out of college.

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

    ...

        As far as the claim that the degree of unpredictability being
        proportional to the degree with which the assembly is reliant on
        compression.... where is the study that supports this ?
        Proportional has
        very a specific meaning when used thus. Strikes me right off
        that given
        the fact that the rib is just as likely to show wide variability
        in its
        strength properties... particularly bending strengths... such a
        claim is
        taken out of thin air. JMMV