This is a multi-part message in MIME format. ---------------------- multipart/alternative attachment ----- Original Message -----=20 From: Erwinspiano@aol.com=20 To: pianotech@ptg.org=20 Sent: January 02, 2004 2:20 PM Subject: Re: No downbearing ? In a message dated 1/2/2004 11:51:20 AM Pacific Standard Time, = pianobuilders@olynet.com writes: I wonder if it was common practice to press boards on a flat = deck which is what I've always heard.(I forget where) Perhaps no one = really knows but even if they were pressed in a dished caul with ribs = that long & usually not very tall how much crown could the panel really = retain over time. I recently saw 1920 ish Knabe upright with very tall = ribs & enough of them. I didn't check the crown at that time but I will = when next I see it. This piano was very well preserved ,great sound. = Thanks for the replies. Dale >From what little I've been able to piece together in talking with some = old bellymen both were common. The dished caul was introduced along with = the crowned rib but was often used with flat ribs in the misunderstood = hope that this would somehow reduce the stress on the panel.=20 In general relatively low, wide ribs are used with compression-crowned = soundboard systems (they must be flexible enough for the expanding panel = to force a crown) and taller ribs are used with rib-crowned systems = (they must be stiff enough to support crown). At the risk of stirring up = once again The Great Soundboard Debates of 2003, ribs do not support = crown in a compression-crowned system. They must be relatively flexible. = The last Knabe upright I was involved with had crowned ribs. Del ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/0c/85/59/9d/attachment.htm ---------------------- multipart/alternative attachment--
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