>I don't understand your basis for saying "The crown is maintained by the >ribs, regardless of rim movement." Simple. A crown isn't an end supported arch. An assembled board will be nicely crowned and support considerable weight before it's even glued to the rim. It's self contained. The rim didn't make the crown in the first place, nor maintain it in the long run. Do the math and report back the difference between the chord (rib length) of an arc segment (panel) 48" long and 0.25" high (crown), and one 48" long, and 0.01" high. Then check the archives and read the tens of thousands of words of explanation to all the already offered counter arguments. > >But certainly if the rim did spread out a bit, it would tend to flatten the >board. So I should think the rods would help maintain crown. Yes? No? No. Ron N
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