Soundboard stiffness variances

[John Delacour]

At 00:10 -0500 13/2/08, Erwinspiano at aol.com wrote:

>>Let's test the properties of spruce over the range of dampness to
>>which it will be subjected and then see how significant the change is.


>   Ok Lets' do it.  I challenge you to do this. FindÊ2 ,Ê36 inch long 
>sections of 1/4 sawn sound board spruce...approx. 6 inches 
>wideÊ.I.e. as if it were cut right out of a panel.  Dry one of them 
>down to 3.5 % emc & the other to about 6% emc. Glue on a flat 
>rib/bar with typical dimensions of what you might find on a sound 
>board of that cross section..,

STOP! Dale.  My test is not that, and if you read what I wrote again 
and understand it, you will see that I am not talking about what will 
happen to a barred strip....

>  EvenÊscallop outÊthe endsÊas is usual. NowÊÊwhile dried down, glue 
>on the rib on a flat table top. Now give it three days in 50% 
>plusÊhumidity conditions & then tell me a few points of moisture 
>content don't' make a difference. One will be far more bowed than 
>the other.

Of course it will!  Nobody is arguing with that.  If you think I am 
then you must regard me as an idiot and can't imagine why you bother 
discussing the point with me.

>  The power of wood cells in compression is enormous...

Yes.

>... & it will produce much stiffness on it's own when its' 
>restrained from expanding on one side.  enough so as to bend a flat 
>pine/spruce rib which is pretty dang stiff all on it's own.

I see what you're saying, but it has nothing to do with what I am saying.

>   I think that because the American climate may be so different from 
>parts of Europe, & that sound board making techniques have adapted 
>to them as well,Êthat our semantics & experiencesÊmay be missing 
>each other like ships in the night.

I haven't studied the American climate, though I know that there are 
big differences in some parts and that makers such as Yamaha use 
different methods when building pianos for the American market, and 
that Bechsteins sent to Canada in the old days simply fell apart, but 
that is beside the point.  I will devise the experiment and you may 
then see what I'm talking about.

JD