Solving Belly Bulge. Should I?

[GusMachado]

Recently, I bought an Ibanez B622 guitar (from the late '70s) and since the top is made of solid wood, I noticed a certain belly bulge on it. In two places:

At the soundhole (but I almost completely fixed this using a damp cloth inside the guitar and a weight on the outside to flatten it).

And under the bridge. In fact, the bridge is even slightly lifted.

My question is:

Do I remove the bridge and use the same technique I used at the soundhole to try to reduce the belly bulge?

Is it really a problem (is there sound loss) in this little lifted part of the bridge?)

[Howard Klepper]

Stop. First do no harm.

Belly bulge per se is not a bad thing that needs correcting. You don't want to damage the guitar by overhumidifying to fix what is not broken. Besides, adding humidity adds to belly bulge. A bridge that is loose can add to it, too. I'd reglue that one.

Take a straightedge and place it across the top immediately behind the bridge. A total of the clearances on the two sides of the guitar between the rim and the straightedge of up to 1/2" (12.7mm) is acceptable and needs no fixing.

[Steve DeRosa]

Originally Posted by Howard Klepper

Belly bulge per se is not a bad thing that needs correcting...

My wife tells me that all the time, bless her heart...

[GusMachado]

Originally Posted by Howard Klepper

Stop. First do no harm.

Belly bulge per se is not a bad thing that needs correcting. You don't want to damage the guitar by overhumidifying to fix what is not broken. Besides, adding humidity adds to belly bulge. A bridge that is loose can add to it, too. I'd reglue that one.

Take a straightedge and place it across the top immediately behind the bridge. A total of the clearances on the two sides of the guitar between the rim and the straightedge of up to 1/2" (12.7mm) is acceptable and needs no fixing.

My only fear is that due to the bulge the bridge wont glue totally straight as it already has this part where I can put the paper. What do you think?

[ChrisN]

Anecdotal experience of 1 non-professional, here, so take it for what it's worth.

Have a '70s Japanese student guitar, lightly built, sounds great. Had a pronounced dip between soundhole and bridge, and the lower bout was bulged. Bridge was rotated (back was raised, front down due to dip), so action was high from that, as well as needing a neck reset. I was concerned this state of affairs would lead to braces coming loose, requiring professional intervention.

I installed a Bridge Doctor and, over a period of several weeks, I kept adjusting it to add tension, and this fixed the dip, reduced the bulge to nothing, and rotated the bridge back into normal stance. I then adjusted the Bridge Doctor to where it applied minimal tension to the bridge, and still permitted good tone. That tension keeps the bulge from returning.

Result - structure restored, no loose braces, bridge level (still needed reset, which it did, but that was a separate issue). I'm very happy with how it turned out (done 2016), and the guitar remains in the same shape, today. Sounds great. I would do it again, under similar facts.

[Howard Klepper]

Originally Posted by GusMachado

My only fear is that due to the bulge the bridge wont glue totally straight as it already has this part where I can put the paper. What do you think?

You are doing a lot of messing with the top in order to take care of a bridge reset issue that you don't know exists. How much belly is there? Have you made a thorough check for loose braces? You seem to have jumped to a conclusion without adequate information. Even if the belly is excessive, the bridge should come off before you fix that.

Take the bridge off, check for any problem with the bracing and bridgeplate, and see how well the bridge fits. Up to a point, it is okay to just force the bridge and top together with clamps when you glue. Beyond that point, I would be more likely to reshape the underside of the bridge to fit the top than vice versa.

[Bruce Sexauer]

Even if there is more belly than you like, glueing a straight new bridge on will go a long way toward correcting it. The bridge can be viewed as the most powerful brace on the top. Using a flat caul on the inside opposing the bridge will easily overpower any curvature I’ve seen in a top. I recently did this to one of my older guitars with total success.

[Truckjohn]

@gus,

You've now heard from several top name professional luthiers. That's very good advice. A mistake on this sort of repair can wreck a fine instrument.

My own advice sort of mirrors theirs... Take this to a good Luthier and have them reglue your bridge. While at it, check/repair for any damage "Under the hood." It happens.

A belly on a guitar, especially a 12-string is a fact of life. If it's not messing with intonation, let it be.

[JLS]

Laminated top, or solid?

[Henning]

You check if belly bulge is a problem by checking the intonation. If intonation and action is ok, then everything is fine.