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A New Martin Bridge

11/1/2012

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martin d-41 new ebony bridge a ruined bridge "shaved" too thin
1. A Martin Guitar.  This one is a model D-41 from the 1970’s and it’s in the shop for a neck reset. 2. The Bridge on this axe was “shaved” thinner a couple years back so that the saddle could be sanded lower in order to put off the neck reset.  Also, the intonation isn’t quite right.
 martin original bridge too thin  martin heat ebony bridge to soften glue
 3. A “Shaved” Bridge.  Normally, the bridges on these guys are about 5/16” thick.  This one is closer to ¼” and the neck angle is still too shallow for this low profile bridge.  Since the intonation needs to be corrected and a neck reset is needed, it just makes more sense to replace this bridge and set the new neck angle to a new, full height bridge.  4. Heating the Bridge with a heat blanket softens the glue.
 remove martin bridge with offset spatula  martin guitar bridge removed
 5. Removing the Bridge with a thin spatula with an offset handle goes quickly since the glue has been softened by the heat. 6. Nice and Clean.  Very little spruce came up with the bridge.  None of the softwood fibers are .005” thick or thicker so there is no advantage to regluing them to the top.
 scrape martin spruce guitar top to get rid of glue  plane ebony with #6 stanley plane
 7. Cleaning Up the Top by scraping the old glue goes fast with the help of a sharp chisel.  I’m using the chisel as a scraper.  8. Preparing the Ebony bridge blank.  I am flattening one face of the bridge blank with a hand plane.
 bench hook shooting board  trace martin bridge
 9. Jointing one edge of the bridge blank to the flat face of the bridge is quick and easy.  I am using my bench-hook shooting board and a bench plane.  10. Tracing the Profile of the new bridge onto the bridge blank.  Since the original profile was ruined when the bridge was “shaved”, I am using a new cnc made martin style bridge as my model.  Unfortunately, these bridges almost never have the same footprint, pinhole and saddle layout as the originals so I have to custom make bridges for most vintage guitars that need new bridges.
 chisel ebony martin bridge  sand wings of ebony martin guitar bridge with spindle sander
 11. Roughing Out the Profile.  I’m chiseling away everything that doesn’t look like a 1970’s Martin bridge.  12. Sanding the Wings into the bridge blank is quick and easy with the luthier’s friend sanding station hooked up to an oscillating spindle sander.
 sand bridge top profile with disc sander  layout bridge pin holes
 13. Shaping the Top profile is pretty fast with the help of a large disc-sander.  I’ve used carpet tape to attach the blank to a flat and square piece of scrap wood.  14. Marking the E Strings’ pinhole locations.
 layout martin bridge pin holes with calipers  drilling pin holes with drill press and brad point bit
 15. Layout is the Key to achieving accurately spaced pin holes.  16. Drilling Out the Pinholes on the drill press with a brad-point bit.
 disc sand foot print of new martin guitar bridge  spindle sand footprint of new ebony martin guitar bridge
 17. Shaping the Footprint of the bridge is pretty quick with the help of the bandsaw and disc sander.  18. Dialing In the Footprint with hand planes and the spindle sander gets a perfect fit.
 sand belly of new martin guitar bridge  sand and polish new martin guitar bridge
 19. Shaping the Belly of the bridge.  I like to use 80 grit self-adhesive sandpaper attached to a paint-stirring stick for this.  20. Final Sanding of the bridge happens with 180, 220 and 600 grit sandpapers.
 glue and clamp martin guitar bridge  saddle slot layout with stew mac intonator
 21. Gluing and Clamping the bridge with hot hide glue.  Next, I’ll reset the neck angle, refret the guitar and make a new nut.  22. Saddle-Slot Layout is precise with the help of this handy tool.  It can also serve as a temporary saddle during a refret in the Erlewine neck jig.
 saddle slot  router saddle slot
 23. Drilling the Ends of the saddle slot help me to position the router for cutting the saddle slot.  It also allows me to avoid plunging with the smaller router bit.  24. Routing the Saddle Slot with a router and a jig.  I’ll make the first few passes with a 1/16” down-cut bit.
 custom saddle slot  martin new ebony bridge
 25. The Saddle Slot is finished off with one final pass with a 3/32” down-cut bit.  26. A New Bridge.