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Martin Bridge Reglue

1/9/2012

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1.0 Martin Bridge Reglue 000 18 headstock.JPG 1.1 Martin Bridge Reglue bridge lifting.JPG
1. This Martin 000-18 was built in 1968. It’s a nice guitar, but after almost a half century of string tension the bridge is begin- ning to pull free from the top. 2. A Lifting Bridge is a common ailment. The best way to address this problem is to remove it from the top, clean up and true the gluing surfaces then reglue the bridge.
1.3 Martin Bridge Reglue score lacquer around bridge.JPG 1.4 Martin Bridge Reglue heating bridge with heat blanket.JPG
3. Scoring the Finish around the perimeter of the bridge is important because there is often a small band of lacquer beneath the bridge that needs to be re- moved once the bridge is off. 4. Heating the Bridge with a silicone repair blanket softens the glue for ease of disassembly. I like to use a couple of steel blocks to hold the blanket in place.
1.5 Martin Bridge Reglue lmi timer.JPG 1.6 Martin Bridge Reglue remove bridge from top.JPG
5. Timing is Everything. 15 minutes of “max” heat is about right for safe bridge removal on a Martin. 6. Removing the Bridge with a thin artist’s spatula with an off-set handle needs to happen quickly before the bridge cools and the glue re-hardens. I’m severing the glue joint about half way in from both the front and the belly side of the bridge.
1.7 Martin Bridge Reglue 000 18 bridge refitting jig.JPG 1.8 Martin Bridge Reglue plane bridge to refit.JPG
7. Holding the Bridge for resurfacing with a standard bridge reglue outside clamping caul. I drilled two holes in the caul for dowels that hold the bridge through the E strings’ pin holes. The “wings” are supported by the thumb- screw clamps. 8. Resurfacing the Bridge with a block plane. I hold the clamping caul in my bench vise as I plane the bridge so it’s slightly concave along its length and dead flat across the grain.
1.9 Martin Bridge Reglue scrape bridge to refit.JPG 2.0 Martin Bridge Reglue scrape spruce top.JPG
9. Fine Tuning the Fit with a scraper. 10. Preparing the Top with a chisel. I’m using the chisel like a scraper, starting at the perimeter of the finish and pulling the tool toward me. This gets rid of the finish and old glue that was under the bridge.
2.1 Martin Bridge Reglue 000 18 inside clamping caul.JPG 2.2 Martin Bridge Reglue 000 18 hot hide glue.JPG
11. The Inside Clamping Caul has grooves to accommodate the bracing and a large section that’s recessed to make up for the thickness of the bridge plate. This caul supports the top and bridge plate inside the guitar. 12. Hide Glue is my glue of choice for a bridge. It resists heat failure and is conducive to future repair work. In order to extend the working time of the hot glue I warmed up the bridge with a heat gun.
2.3 Martin Bridge Reglue 000 18 glue and clamp bridge.JPG 2.4 Martin Bridge Reglue 000 18 clean up squeeze out.JPG
13. Clamping the Bridge while the glue cures for 24 hours. The outside clamping-caul has two thumb-screw adjusted clamps that hold down the wings of the bridge. 14. Hide Glue Squeeze Out is easy to clean up. A few minutes after the bridge is clamped, a small dowel with a single bevel safely knocks free the squeeze out.
2.5 Martin Bridge Reglue 000 18 bridge reglued.JPG 2.6 Martin Bridge Reglue 000 18.JPG
15. A Reglued Bridge repaired with hide glue will stay put for a long time to come. 16. The Repair is tough to spot because the bridge fits perfectly inside the area of the removed finish.
2.8 Martin Bridge Reglue 000 18.JPG
17. All Done.