Spurlock shimming method.

[Ron Nossaman]

><<"A soundboard isn't in any way the surface of a balloon.">>
>
>Never said it was exactly...... what I 'did' say was "The analogy ain't 
>perfect but merely a reasonable facsimile :-)"

No, that's the point. It isn't a reasonable facsimile. The skin of the
balloon isn't the driving mechanism, where the panel of the soundboard is.
They're entirely different.



>And the top surface of a soundbaord does expand and contract. as does the 
>surface of a ballon...if'n it didn't?............. how doe the sucker gain 
>and lose crown?....Or form "pressure ridges"? Or accumulate "compression 
>damage"?

Because wood changes dimension with humidity changes, and these dimensional
changes drive the entire process. You see, in most parts of the world, the
humidity isn't a steady 99% all the time so this may be a regional concept.
That's the key point that must be understood before any of this other stuff
makes sense.



>"arch buttresses do not form or maintain" anything either they merely hold 
>something in place by providing resistance.....anything held in place by a 
>"buttress" will react to that "buttress" within the limits of that "butress" 
>and the characteristics of the material being held. If you take your flat 
>ribbed ,flat paneled, sounboard and stick it in your hot box and 'not' 
>restrain it in some way after it is taken out.....all you will have is a flat 
>board that basically gets hotter and cooler 'without much' change vis a vis 
>crown. 

I know what a buttress does, and the ribs are the constraining element.
Once again, the assembly is crowned and will support a considerable load
before it is ever put into the rim. The rim does not support crown - the
ribs and panel compression do. 


 
>......... the archives show just as much dis-cohesiveness of 
>"the extensive and voluminously detailed discussions" and thoughts as they 
>did originally and are displaying currently. :-)
>Jim Bryant (FL)

Only where folks have refused to accept basic principals of physics. This
stuff is provable by demonstration any time you care to try it.


Ron N