Rib Support

Cy Shuster 741662027@charter.net
Sun, 26 Oct 2003 12:32:58 -0600


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Ric,

Thanks for spending the time to do the diagrams.  It really helps the =
discussion.  I'm going to take a wild stab, based only on intuition, so =
I won't even bother with a flame suit.  It's supposed to snow today, =
anyway -- we could use the heat!

It seems like it's a matter of degree.  A force can exist, but be so =
small as to be negligible.  The Moon has a gravitational pull to be =
sure, but the Earth's is so much stronger, it's irrelevant.  A =
soundboard decal undergoes stress when a board is crowned, but it's =
irrelevant.

The situation seems more like a stronger force overcoming a weaker one.  =
The weaker one subtracts from the stronger one, and then the situation =
is in equilibrium.  I'm thinking of a small leaf spring, like for =
pedals, about 6" long, say curved in an arc of one foot radius.  It =
resists being straightened.  If you take a stronger spring, of thicker =
metal, same length, but curved to a 6" radius, and nest the two so the =
stronger's on the outside, the thinner spring will resist a bit, but the =
vector of its force is overwhelmed by the stronger spring.

Same with the soundboard and ribs.  If the force of the SB absorbing =
moisture is so strong as to bend the ribs, then they're irrelevant after =
that point, it seems.  The material used seems to matter.  If the ribs =
were spring steel, and were initially flat, then of course they'd =
continue to want to straighten out, forever.  What does wood do?

If the SB were stronger than the ribs to begin with (after coming up to =
normal humidity), wouldn't it always stay stronger than the ribs?

--Cy Shuster--
Rochester, MN

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