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Gibson Bridge Reglue

8/30/2013

 

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1. A Gibson L-00.  This one was built in 1941 and is in the shop for a bridge repair and reglue as well as a few other repairs. 2. A Low Saddle.  This guitar needs a neck reset in order to play better.  A well meaning repair person sanded the saddle until it was practically flush with the bridge in an attempt to make the guitar playable.  At least the bridge itself hasn’t been “shaved”.
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3. Deep Grooves in the bridge are an aftermarket attempt to give the strings some break angle over the extremely low saddle.  I’ll fix these notches while the bridge is removed from the guitar. 4. Bridge Bolts.  There are two pearl dots inlaid into the bridge.  They conceal two small machine screws that go all the way through the bridge, top and bridge plate.  I’m not sure why the rosewood is chipped around the pearl dot but that’s a relatively simple fix.
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5. Lifting Bridge.  The bridge top glue joint is failing.  I can fit a post-it note under the bridge all the way to the pin holes from the rear of the bridge.  After I remove the strings, I’ll reach inside the guitar and remove the nuts from the machine screws. 6. Out of Alignment.  The bridge top glue joint is mis-alligned.  I can’t get the post it note to slide under the wings of the bridge which indicates that the bridge is still partially glued to the top.  Hide glue doesn’t creep like yellow glue so perhaps the bridge was glued out of alignment by a previous repair person.
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7. Heating the Bridge with a heat lamp will soften the glue that holds the saddle in the slot, the pearl dots in the bridge and the bridge to the top.  I’ve masked the top with a piece of cardboard with the bridge’s shape cutout a tad oversized and the whole thing loosely covered in aluminum foil.  I’ve mashed the loose aluminum foil into the space between the cardboard and the bridge in order to protect the finish from the heat. 8. Removing the Saddle with flush ground end-nippers.  The old saddle has simply broken in two which is fine since I’m going to replace it with a taller, bone saddle.  Next I’ll remove the bolts and pearl dots from the bridge by tapping on the bottom of the screws with a heavy steel block from inside the guitar.
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9. Removing the Bridge.  Normally I use an offset artists spatula to free the bridge from the top.  In this case that was unnecessary because tapping on the end of the screws fractured the remaining hide glue joint which freed the bridge from the top.  I’m not sure if the bridge was previously reglued.  Perhaps some repair person couldn’t get the bolts free and decided to simply work some hide glue under the misalligned bridge and clamp it down. 10. Removing the Bolts.  With the bridge still fairly hot, I’m tapping the bolts and pearl dots free with a small hammer.  The bridge is top down on my workbench with the dots and bolts suspended over a round doghole in my workbench.
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11. Preparing the Bridge in the usual fashion is pretty quick.  I’m scraping away the old glue with a chisel then I’ll flatten the bridge accross the grain with a plane, PSA sandpaper on a short flat block and a scraper.  The bridge is already arched with the grain to more or less match the arch of the top. 12. Filling the Notches in the bridge with a mixture of super glue and rosewood dust is fairly quick.  I’ve also reglued the pearl dots with super glue.  I won’t be reinstalling the bridge bolts.
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13. Sanding the rosewood dust and glue flush is pretty quick with the help of some 80 grit PSA on a polyurethane coated paint stirring stick.  Next, I’ll hand-sand the bridge with a small, cork-lined block with progressively finer grits of sandpaper ending in 600 grit. 14. Scoring the Finish of the top around the bridge with the bridge temporarily clamped in position to the top is the first step in preparing the top.
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15. A Sharp Chisel and a scraper made from a razor-blade knock down the high spots and remove any old glue, oxidation and finish from under the bridge. 16. Regluing the Bridge with hot hide glue, a deep throat c-clamp and two clamping cauls.  The inside caul is notched to accommodate the internal bracing and bridge plate.  The inside caul is also steeply radiused to match the top of the guitar.  The outer caul is the stew mac bridge reglue clamping caul.
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17. A Reglued Bridge.  After allowing the glue to cure for a couple of days I proceeded with the other repair work including fitting new bridge pins, a neck reset and new bone saddle. 18. Done.