Soundboard recrowning and rib re-arching.

[gordon stelter]

Well, no, haven't had time to check that out. But I'm
still 100% incredulous about the claim that a crowned
board, pushed down at the apogee, will pull in at the
edges. Until I see it, or someone adequately explains
it, I don't believe it. I may be stupid, but my Dad
invented a lot of the stuff in computers today, and my
brother holds 35 patents in optical physics, and this
just doesn't "add up", to me!
     Thump 

--- Ric Brekne <ricbrek at broadpark.no> wrote:

> Thumpy writes:
> 
>     Yeah yeah Ok sure. But none of this changes the
> fact
>     that if you stressed the board into an
> exaggerated
>     crown, then permeated the ribs ( and board,
> maybe )
>     with something that rersists compression, you
> ought to
>     end up with better crown when you "knock the
> chocks
>     out".
> 
> T
> 
> No argument on that point.
> 
>     P.S. Still, that rib matter has to go somewhere
> when
>     the board loses crown. Either the rib is
> compressed
>     longitudinally, over the decades, shrinks, or
> the rim
>     expands. Probably a combination of all three.
> This is
>     simpleton stuff.
> 
> You might at best experience a little end grain
> crushing from any 
> constraint from the rim.  And we are talking
> reallllly small amounts. As 
> far as being compressed in the face of the
> soundboard panel itself going 
> flat... well I'm open for any data you might have,
> but the relative 
> stress levels the rib and panel can handle would
> kinda indicate to me 
> that you are probably in error.  Not to worry tho...
> that same argument 
> is used to tell me that I am entirely wrong about
> ribs supporting crown 
> in a CC board to begin with. 
> 
> Back to your point about rim expanding or rib
> compressing... you ever 
> try that experiment Nossaman sketched a couple years
> back ... the one 
> about checking out the buttressed arch concept ?  I
> found that rather 
> enlightening myself.
> 
> Cheers
> RicB
> 


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