This is a multi-part message in MIME format. ---------------------- multipart/alternative attachment Re: Bridge designSorry Del, I thought the discussion had gone to the treble end of the long bridge. = I haven't seen a transition bridge setup yet but I'm sure I will soon. A laminate structure is far more resistant to flex. Bend too = straight pieces of wood and glue them together. They want to stay where = you glued them and will stay that way longer and with less warpage than = a piece of solid wood cut that way. (presuming the glue joint....etc.) = I've been in the construction trades 30 years and a laminate beam is far = more desirable structurally than even pattern nailing a bunch of boards = together. Now here's where I may be presuming two much. It seems to me, as the = bridge is loaded and the soundboard/bridge structure approaches the = point of failure, the impedance would change exponentially. Small = initial changes can become major. In my limited experience I haven't = heard of any real model test of 2 identical boards and bridges glued up = and run through a battery of tests. It was my feeling (my 2 1/2 years of = engineering at UCSB is now a jigsaw puzzle with a bunch of missing = pieces), that the glue joint as a variable might not have been coorectly = assessed. Keith R Conrad! You better throw in a technical disclaimer along with the = automatic reworder on my new flame suit. And HURRY! ----- Original Message -----=20 From: Delwin D Fandrich=20 To: pianotech@ptg.org=20 Sent: Sunday, July 07, 2002 7:20 PM Subject: Re: Bridge design ----- Original Message -----=20 From: Keith Roberts=20 To: pianotech@ptg.org=20 Sent: July 06, 2002 7:52 PM Subject: Re: Bridge design Maybe gluing the bridge cap on in the crowned position and the = bridge to the sound board in the crowned position, like Dale does, will = add the necessary impedance to the treble end of the bridge.=20 It's not the treble end of the long bridge that is in question here. = It's the bass end of the long bridge. And no amount of crowning the = bridge to match the crown of the soundboard is going to affect that. Or = much else, for that matter. Most of the models discussed here on the list, didn't seem to deal = with the stiffness added by the glue joints in a laminated structure. = Usually underestimated and throws that kink into the reality/theory gap = along with a few of the other observartions Dale has made. Would you care to explain this a bit more? How does stiffness added by = the glue joints in a laminated structure -- assuming there is any -- = affect the impedance of the very end of the long bridge? Del ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/ee/41/38/3c/attachment.htm ---------------------- multipart/alternative attachment--
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