brace

X-Brace Repair

A broken x-brace is a serious matter.

Inside most steel-string acoustic guitars, there are a number of braces. They’re glued to the top (and the back) to provide strength—without them, the string tension would just pull the guitar top apart.

Most guitars these days (and for some time) are ‘X-braced’, so called because, as you can probably imagine, the two main braces intersect around the bridge and form an X shape. While there are a number of other, smaller braces on the guitar top, it’s the two x-braces that do most of the work.

When one of these breaks, it’s a big deal. Your guitar top can deform, your bridge and bridge pad may become loose, and your guitar can be ruined.

In an ideal world, a broken x-brace would be removed and a new one installed in its place—it’s under a lot of stress and ‘new’ is preferable to ‘glued’ in this instance. However, it’s not usually possible to replace an x-brace through the sound hole since they’re too long. This makes replacement a pretty massive job involving the removal of (probably) the guitar’s back. It’s not something that is done lightly and the cost may be hard to justify for many instruments.

Sometimes you can get lucky, though. While a repair to an x-brace isn’t always possible or advisable, some breaks lend themselves to repair more readily.

Broken x-brace

This one, for instance.

The break is long and easily accessible from the sound hole. The brace is relatively wide and provides a fair amount of glueing surface.

And, the icing on the cake, there’s a flat top on the intersection. This means I can add a little patch there to provide some extra insurance that the repair will hold.

Glueing and clamping the split is straightforward. I want to show you that patch I mentioned.

Reinforcing patch for x-brace

Many guitars already have a patch like that shown above on their X intersection. I’ve left one ‘leg’ of the patch a little longer. This will extend a little farther down the broken brace. The pencil lines show how it will sit on the braces.

Clamping up

Working through a sound-hole is frequently a fiddly job but things are nicely within reach here. A regular G-cramp does the trick. You might see a little bit of tape on the patch. That was just to keep it in place and aligned as I clamped it.

Patched. 

And here’s the finished article. Brace glued, patch applied, and new life for this guitar. 

Repairing Loose Acoustic Guitar Braces

Visible gap on loose acoustic guitar brace

Glued inside the top and back of your acoustic guitar are braces. These are wooden support beams* that provide strength to what are, otherwise, relatively thin pieces of wood. 

Sometimes a brace can become loose. This could be because the guitar gets a knock but, often, some or all of the glue can just fail for a variety of reasons. 

A loose brace can be a pain. If part of the guitar isn't properly supported, it can pull and warp in unpleasant ways. That's generally not good. In addition, one symptom of a loose brace (and frequently the one that leads to its being discovered) is a nasty buzz or even a rattle when some or all notes are played. Often this buzz is located around a certain note (a tone or so either side) as the loose brace vibrates in sympathy. 

These can be an incredibly frustrating thing to track down. Sometimes you'll get lucky and be able to see the gap between brace and top/back (like in the photo at the top—the shadow beneath is clear) but, more often, you'll end up, up to your elbow in the sound-hole, poking at joints with a feeler gauge, trying to find a tiny gap. It's a real pain. 

When it's found, the gap should be cleaned and the old (failed) glue removed. Then, fresh glue is worked underneath the brace and the repair is clamped up to cure. This sounds straightforward until you try doing it, at the limit of your reach, blind (or, with an obscured reflected image in an inspection mirror).

Loose acoustic guitar brace

Find loose guitar brace

Not so with this one, though. These are back braces and they're relatively easy to get at. This particular guitar did actually get a knock and has had a previous repair for a back/side separation. I can't be certain that these braces were knocked loose at that time but it seems likely. Maybe not, though—benefit of the doubt for the previous repairer.

You can clearly see the feeler gauge poking under the braces in the photos. The blue tape is something I've put in, by the way. It keeps the mess down when working glue under the brace. 

Once there's a good smearing of glue in there (and it needs to be worked well under to get a good joint), a bit of a wipe up, and then it's clamped (see below). The little scissor-jack thing is a god-send for these jobs—it gives decent clamping pressure and I can wind it up from outside the sound-hole. 

On this particular instrument, this has to be repeated a few times as I found four loose ends. But not any more more. All re-glued and sorted. 

Glueing and clamping loose back brace on acoustic guitar

*I think 'beam' is the correct structural term for guitar braces but any engineers can feel free to correct me. Beam tends to make most people think of massive steel joists, however, while guitar bracing tends to be a little smaller. And wooden.