This is a multi-part message in MIME format. ---------------------- multipart/alternative attachment ----- Original Message -----=20 From: Mike Kurta=20 To: PTG List=20 Sent: Sunday, May 25, 2003 6:49 AM Subject: Bass bridge puzzler Hi Gang: Two weeks ago, I duplicated a bridge for a local tech from a 10 = year old Baldwin console which had split in the usual manner. After = installation and attempting to pull the bass strings up to pitch, the = new bridge split again down the pin line on the speaking length side of = the bridge. Will now have to make another, but don't want to have the = same result. =20 A few points: Hard rock maple was used, the dimensions, pin size = and positioning were all closely duplicated, and finished with DAG along = the top. Grain orientation was followed according to PTG information. = The new bridge failed the same way as the original one. We did not = measure downbearing, felt there was no need. =20 We are looking at some possibilities: 1. I used the entire = length of the new pin into the wood, did it weaken the bridge along its = length? Did the pins drive in too tightly starting the split? Was = there a flaw in the wood? I havn't seen it yet, so will examine. = Should I use smaller diameter pins next time? Should they be angled = more toward the center (each other) at the bottom of the bridge? Was = there a design flaw in the original bridge we are repeating? =20 Any ideas? HELP ! =20 Mike Kurta Maybe the wood wasn't cured. I had one duplicated by Schaff that = split despite all my precautions. I suppose it's possible that bridge = pins driven in too hard might help it split. I've had even soft pine = split when driving in nails, even when I pre-drilled a hole for the = nail. This happens more often at the end of a board than in the middle. = Maybe if both the sides and the end were clamped somehow while driving = pins . . . or use one drill size larger? --David Nereson, RPT ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/19/78/a5/5a/attachment.htm ---------------------- multipart/alternative attachment--
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