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: July 25, 2003 1:40 PM Subject: Bridge attachment There are obviously several ways to clamp a bridge to a new soundboard = while gluing - pneumatic press, go-bars, screws with their holes later = filled with dowels.=20 Suppose one is using screws. I have heard several people say they = don't like to drill through ribs. The old Steinways had a combination of = screws through every rib which were then dowelled, large dowels up into = the areas between the feet of a footed bridge, and screws through = soundboard buttons in the high treble which were just left in place. Is = there a better way, if one is using screws? It seems like drilling = through ribs weaken the ribs, a hardwood dowel through a thin softwood = soundboard between the ribs could break free later and buzz, and a screw = left in place through a soundboard button could loosen and buzz, = especially since many are inaccessible. Drilling through the rib does weaken it. This is not a problem if the = soundboard is compression-crowned. In this case the rib is not = supporting crown, but resisting it. It needs to be some flexible.=20 In the case of a rib-crowned soundboard system the rib is a structural = member. It is not a good idea to do anything that would weaken the rib = right at the point where you are putting the most stress on it--directly = under the bridge.=20 Most of those who use screws and buttons to attach bridges put them in = between the ribs, not through them.=20 It is true that a screw left in a soundboard could cause a buzz sometime = down the road. But then so will a loose rib. Perhaps we should leave the = ribs off as well. Seriously, enough screws have been left in enough = soundboards over the past 150 plus years that if this were going to = develop into a severe problem it probably would have done so by now. Del ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/c0/5c/10/71/attachment.htm ---------------------- multipart/alternative attachment--
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