More on soundboard crown

[Richard Brekne]

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Delwin D Fandrich wrote:

>
>
>      So assuming that Climatic conditions can get over stress
>      even an RC panel... I just was musing if there was some way
>      of contiving a rib that gave crown support, but was a bit
>      less constraining to the panels tendancy to expand and
>      contract across the grain.... sort of sliding ribs if you
>      get my meaning...Probably a silly question I know... but I
>      was just curious.
>
> Well, sure. I expect you could somehow slip-joint the panel to a set
> of crowned ribs much like a solid wood table top is attached to its
> frame. Theoretically, at least. I expect there might be the random
> buzz or two in real practice.
>
> Del
>
Hi Del... actually... I was rather thinking (again perhaps another one
of those bunny trails...) that perhaps one could add about a 1/8th inch
thick strip of left over sounboard material to the top half of the rib,
grain in the same direction as the panels. If it was dried to say 6.5 MC
prior to attachment to the rib... and the soundboard was dried to say
4.5 MC why wouldnt this tend to sort of buffer the ribs cross grain
constraint ? When taking on humidity this layer would get slightly
compressed by the rib... and since its grain is in the same orientation
of the panels it wouldnt force that into nearly as much compression....
er.. I think :)... If there was not enough crown you could rib crown
enough to make up the difference. I suppose you could rib crown to begin
with.. but if this provided a kind of solidly glued  << slip joint >> ,
and if there was some good reason to dry out the panel to 4.5 MC as long
as one could avoid exceeding the stress limits... well... Anyways.. I'm
just fooling with ideas in attempt to better sort out what does and
doesnt happen. yes ??

RicB







--
Richard Brekne
RPT, N.P.T.F.
UiB, Bergen, Norway
mailto:rbrekne@broadpark.no
http://home.broadpark.no/~rbrekne/ricmain.html
http://www.hf.uib.no/grieg/personer/cv_RB.html


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