Thanks for the comments Terry. A couple answers to your questions below. Seems like perhaps I should be thinking about gradual tapering here from the sound of your post. Cheers RicB Farrell wrote: > Hey Richard, > > I'll stick my neck out - not that I am any authority at all on this > subject - but perhaps it will stir something up. I figure if I say > something outrageous enough, then someone that knows what they are > talking about will chime in. > > On a compression crowned soundboard, like a Steinway, the rib acts as > something to keep the one side of the panel from expanding when the > panel takes on moisture upon removal from the hot box - that is what > makes the panel crown. The ribs will be of constant thickness so that > the soundboard develops crown evenly. The ribs are thinned only at the > end to keep the soundboard flexible at the perimeter. > > A rib crowned soundboard will have ribs that are more evenly tapered > over most of their length, such as the taper you describe. That is > because such a shape better supports a load when applied to the middle > of the rib, such as downbearing on the bridge. That is what I think, > but you'd really need input from an engineer type to say more about > that subject. > > Now all other manufacturers use the Steinway-shaped rib because that > is what Steinway does. > > Is your soundboard crowned? Compression crowned? Rib crowned? Ribs are at a mild crown... close as my rough work could get to a 90 foot radius. They were glued on after the panel had been in 27-28 % RH for 3 weeks... so whether what degree of Compression that will create as it takes on summer humidity will qualify this as a compression crowned board or not I dont know. My plan was to have mild rib crown support, combined with mild compression crown tenancies. It is, after all, a small square grand and has a very light scale. > > Terry Farrell >
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