Dale, Those ribs were originally built into a CC board. How can a compression crowned board get mechanical support from the rib scale, however "good" the scale looks? The ribs in CC boards resist the crown that panel compression is trying to form and maintain, and just put more compression load on the panel. -----Ron No, I get all that Ron, but if the ribs are built significantly taller & of stiffer material by design then more panel compression can be taken out of the equation. Another thought is, & I've witnessed this quite a few times is, that Stwy A's (1 & 2"s) in general can produce a pretty wonderful sound even with a flat or flattish board providing there is some small but consistent bearing load still intact so in this case it would seem that there are enough impedance factors about the rib scale to make the system work rather well. Ok maybe a freak of nature but it happens fairly frequently. About 5 years back I had such an long A I was going to resell it. It had Steinway hammers which were quite soft & made it sound really good. It was hard to imagine that a new board would make it sound much better. It truly sounded glorious but it was a spec job & I don't sell old boards very often. I didn't do any thing to the action until later for a really good A b comparison. So I built a board with the same number of ribs making them crowned at about 60 ft. Made em taller but not much. Used sugar pine in the bottom & yellow pine in the top. The sound was cleaner and the sustain was about the same which was awesome. It just had it!! I attribute much of this to the original basic rib scale design. Something was working or several things were. Do you see what I'm saying? I'll crunch some numbers & see what I got. I greatly Appreciate the design sharing & information swap. Thanks Dale It's an entirely different system. Do a bearing load analysis on the ribs as load carrying beams and see what the numbers say. They'll say that the rib scale isn't adequate to support bearing without substantial panel compression support. Ron N -------------- next part -------------- An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/20060403/3b5e8abb/attachment.html
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