This is a multi-part message in MIME format. ---------------------- multipart/alternative attachment -----Original Message----- From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org]On Behalf Of Terry Sent: January 24, 2005 4:03 AM To: Pianotech Subject: Re: Crowning methods, was soundboards. > | ....The other > | end of the spectrum would be no panel drying at all, and ribs cut/formed to > | the desired radius. I am not aware of anyone that is at that end of the > | spectrum. > > Walter. Really? They rib with the panel equilibrated with room RH - somewhere in the 9 or 10% moisture content range? And then they sell a piano in Minneapolis? Any idea how those boards look after a few years and a couple hundred cycles of high to low environment RH? Any increased tendency to crack? I misunderstood your comment. Walter is supposed to rib their boards with the panel at 6.5% MC, +/- 0.5%. Not particularly low being just under the minimum MC recommended by most glue and adhesive manufacturers. ---------------------------------------------------------------------------- -- > | I believe most soundboard manufacturers build hybrid soundboards - that is > | the ribs will have some radius cut/formed into them (often the 60-foot > | radius one hears of so often) and the panel will receive a fair bit of > | drying prior to ribbing. Steinway even modifies the 100% compression > | crowning process by drying the panel, using flat ribs, but gluing them to > | the panel in radiused cauls. > > The result of this is still a pure compression-crowned soundboard. (Think about > it....) > > Del Absolutely. I understand that. Perhaps I chose my words poorly. I did not mean to suggest that the Steinway grand soundboard was anything but 100% compression-crowned, but rather was pointing out one variation of the 100% compression-crowned method: ribbing with a flat rib in curved cauls, as opposed to ribbing a flat rib and clamping to a flat surface. Sadly I've had this discussion with several factory people who seem to believe that by pressing flat ribs to a panel at, say, 6% to 7% MC, to curved cauls does not constitute compression-crowning. But it does. The results are exactly the same -- you end up with a pure compression-crowned soundboard assembly. And, hence, my earlier response to you. Del ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/ed/e5/60/45/attachment.htm ---------------------- multipart/alternative attachment--
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