This is a multi-part message in MIME format. ---------------------- multipart/alternative attachment ----- Original Message -----=20 From: BobDavis88@aol.com=20 To: pianotech@ptg.org=20 Sent: May 08, 2003 8:27 AM Subject: Design of cutoff bar Many pianos with cutoff bars have an open space, or a different = species of [filler] wood outside the cutoff. Is there a way to gain the = acoustical advantage of a cutoff bar, but have it appear traditional on = the top side? For instance, could the ribs be notched and continued on = to the rim, just to support this area? I realize this is a waste of good = spruce, but it would not call attention to itself, and there are some = situations in which that is a good thing. Yes. In some cases we leave the soundboard full-size and glue it down = over the cutoff. We still terminate the ribs at the cutoff and use short = pseudo-ribs between the cutoff and the rim to support the dead area of = the soundboard. It is much more difficult to glue up this way and we = resist doing it unless the client is really insistent. Generally we glue = up in two stages. The soundboard board goes in first so we have ready = access to the cutoff for clamping. Then the filler goes in. Clamping is = not a critical. We always put something in there to keep acoustical = energy from cross-coupling around the edge of the cutoff. Is the cutoff bar affixed to the beams? In one picture it appears to = pass over the metal termination plate for the beams. Is this a problem? Yes. It is glued and doweled. In general we cut away for clearance = between the cutoff and any metal components (Usually incorrectly called = "tone-collectors") that may be down there. This includes any = "Centripital Tension Resonators" that may be in the way. It appears to be the approximate cross section of a bridge. Am I seeing = this right? No. They are some larger that that. I usually make them 50 to 60 mm wide = and between 30 and 50 mm tall. They are made of maple (usually). Del ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/29/45/58/0d/attachment.htm ---------------------- multipart/alternative attachment--
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