The bridge will sometimes pull up from the top of your acoustic or classic guitar. Causes can include a poor job of gluing at the factory; letting the guitar get hot (as in leaving it in a closed car in the sun), which can loosen the glue—and the bridge having 150 pounds or so of pull on it, weakened glue joints often strike here first; too heavy a gauge of string for that particular guitar; and other factors.
Guitar techs currently charge somewhere in the vicinity of $50 to repair this condition. Now, for $50, you can probably get the tools you need to do the job yourself (though the reader is respectfully warned to NOT try this at home if one is not confident with woodworking tools, or in his/her ability to do the job as described below).
Regluing a bridge ain’t rocket science, but it does require a few specialized resources:
1 – To remove the bridge, get a standard-size putty knife and modify it by thinning the blade . A little drum sander will do the job. You want the tool to be much thinner and more flexible than stock, and sharp as a knife at the end. Once the tool is ready, remove the strings and pins from the bridge, and gently work the knife in under the bridge from ALL sides, gradually separating the bridge from the top. Be careful NOT to use too much pressure! And keep the blade flat against the top. Be patient and take your time with this. It should hardly need to be mentioned that if you are not careful you can scratch the top finish, or slip and gouge something (including, perhaps, your hand). Work your way only to about the center of the bridge, don’t attempt to go all the way under the bridge to the other side.
2 – Using the drum sander, grind away all the residual glue from the bridge. Be careful to use nice even strokes as you work the bridge over the sanding drum so as to not grind cavities into the wood. You want the underside of the bridge to be nice and flat when you’re done. Be especially delicate with the edges so you don’t round them off.
3 – Using a small wood chisel, remove old glue from the top of the guitar, being careful to stay within the footprint left by the bridge, and not slip or gouge the top.
4 – To properly reglue a bridge, it needs to be properly aligned. This can be easily accomplished on pin bridges by using 3-4 tapered-head bolts of the appropriate size and length, which go down through the pin holes and tighten underneath. Use washers to avoid damage to the inside of the top.
5 – Then there are the clamps. Acoustic guitars are more forgiving than classics in this regard, since the bridge is typically closer to the soundhole than on a classic guitar. Nonetheless, at least 3 deep-throated clamps are needed to reach through the soundhole to apply uniform pressure to the bridge as the glue dries. Standard deep clamps from hardware stores can be used, but can be rather bulky and space-consuming. There are specialized clamps used by luthiers for this job, which I would recommend buying. Three clamps are goodÑ4-5 are better, as you may need them for more recalcitrant bridge jobs.
Check Stewart-McDonald Luthier Supplies for your clamps.
6 – A small wooden dauber to remove glue that will get squeezed out from the bridge. You can take a popsicle stick and whittle it down to a point at one end and to the size of a small screwdriver at the other end for this.
7 – A few wooden cauls (small blocks of wood, basically), used to protect the bridge and underside of the top from clamp marks. For extra protection, some cork glued to the side that contacts the guitar is a good idea.
8 – For the finishing touch, a small tapered wood reamer is needed to remove excess glue from the pinholes once the glue has dried and the bolts are removed.
OK. Armed with the above tools (and a bottle of yellow hide glue), here’s the procedure:
Apply a thin, even coat of glue to both bridge and top. Put the bridge onto the top and using your 3-4 bolts through the pinholes, align and tighten the bridge down to its final position. Check alignment carefully—this is your last chance to nudge things.
The bolts will do a good job of clamping the area of the pinholes, now you need to securely clamp the ends of the bridge. Take a deep clamp and duct tape a wooden caul to the foot that goes inside the guitar. Open up the screw on the clamp all the way so you can snake it into the guitar without scratching the top. Place another caul at one end of the bridge (cork-side down), nicely centered to apply even pressure. Make sure the inside foot is not riding on a brace, as clamping down on this will damage the brace. When things are nicely positioned, clamp the sucker down. Use sufficient pressure to squeeze out the excess glue nicely, but to avoid damage, don’t over-tighten (the sound of crunching wood coming from inside your guitar is a bad sign—back off!).
Use your dauber to gently remove excess glue from the top around the bridge. Inspect to make sure that all edges of the bridge are tightly secured to the top. One clamp at either end of the bridge and another in the center to help the bolts flatten that area to the top is usually sufficient, but sometimes you’ll notice an area where spaces exist between bridge and top. Immediately adjust your clamps (or use additional ones) to achieve good, uniform contact. Continue cleaning away excess glue. A warm damp (NOT wet) rag can be used to clean up anything left over from the dauber.
Let the guitar sit for several hours. Overnight is recommended.
Remove the clamps and the bolts, and then use the tapered wood reaming tool to remove the dried glue from the pinholes. A few turns will do the job (don’t overdo it or your pins will be loose in the holes). There will be some resulting bits of garbage left inside the guitar which you can suck out with a shop vac.
Restring your axe and pray. 😉
Copyright 2002 Jeff Foster. All Rights Reserved.