> Percent residual crown doesn't tell you much in a system that has variable > radius control. If you start with a rib that has 10 mm of crown and deflect > it 5 mm it has 50% left. If you start with a rib with 5 mm of crown and > deflect it 5 mm it has 0%. But they both have the same amount of deflection > for the given load. Thank you David! I keep trying to make this point: we should all be including the span with our crown data, without which the data is absolutely meaningless! Further, if we can't predict this sag, we can't predict the dynamic bearing and angle of string deflection, which means we don't know the pressure and are going to have a rough time of making any rib scale that isn't a shot in the breeze. BTW, while I don't make CC boards anymore, I did apprentice in a shop for several years that made about 20 CC boards a year and I have to say it was like being in the Wild West. We were total cowboys. The only thing we paid attention to was emc (3.5%). Rib dimensions came right off the old board, the compression crowning was all over the place depending on the time of year and size of the panels/ribs, and we set distance bearing with the spare change in our pocket. Yee haw! Boy were those days fun and also one of the reasons that I'm so compulsive now. :) Jude Reveley, RPT Absolute Piano Restoration, LLC Lowell, Massachusetts (978) 323-4545 -------------- next part -------------- An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/20080127/5f73f6c0/attachment.html
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