Acoustic bridge coming off: FIXED!

Acoustic guitars can be designed to sound good, or can be designed to last – it can’t really be both. Most builders try to find a middle ground, and many are very successful at finding a perfect balance. However, guitars are mostly made of wood, and sometimes wood just won’t cooperate. Occasionally we see this kind of problem: an acoustic bridge coming off. This particular guitar was rather problematic, and we were told that several other luthiers didn’t want to even attempt to fix it. But we’re the type of people that just can’t say no to a challenge, so here we go!

Here’s some preliminary shots of what this guitar looked like when it came in. This was probably the worst case of an acoustic bridge lifting we’ve ever seen: the bridge was coming off, the top had severely warped, and the bridge plate underneath the top was cracked and misshapen. Oof!

Someone had previously attempted to fix this, and did a rather poor job of it. They had glued the bridge back down without properly addressing the root issue of the top deflecting, and to make matters worse they bolted the bridge down!

Here’s the bridge plate on the inside of the guitar. It is severely cracked and warped.

Whenever we’re dealing with a poorly done repair, it just makes the repair all the more difficult. While we certainly don’t try to discourage people from attempting to repair things on their own, just bear in mind that you might screw it up and make things worse! This one was going to be a doozy.

The first thing I needed to do was to remove the bridge, which was made somewhat difficult with the bolts that had been installed. The bolt heads were hidden under some pearl dots, and I didn’t want to risk drilling the inlays out lest I strip out the bolt heads and put myself in a heap of trouble getting them out. So instead, after removing the nuts from the inside of the guitar, I put my soldering iron inside against the bolts, which would melt the glue holding the dots in place. Once the glue melted, I was able to push the bolts up from the inside.

With the bolts removed, I heated the bridge with a heat lamp to melt the little bit of glue still holding the bridge on, and lifted it off the top with a knife. It came off pretty clean, all things considered:

You can see how badly the top was warped and cracked under the bridge. Yikes!

Believe it or not, removing the bridge was the easy part. Next, I had to remove the broken bridge plate inside. I fashioned a way to introduce heat to the inside of the guitar, softening the glue holding bridge plate to the top, and then spent the better part of an hour with a short chisel prying it off. It came off in pieces, and it wasn’t surprising when it took some of the top with it. I said this was going to be a doozy!

The bridge plate came off in five pieces! I’ve placed them together to get a rough outline of the shape.
Holy smokes! The top was so cracked and fragile that it collapsed as I was removing the bridge plate. What fun.

Since the top was so compromised, some of it came off with the bridge plate. I had five small pieces of spruce that I salvaged from the mess, and very meticulously glued them all back together, like so:

Not bad, huh?

Next I pressed the top back flat, utilizing heat, some Thompson cauls, and a plank of oak. After a couple of treatment sessions, the top was in much better shape.

While I was at it, I repaired a few braces that had cracked and/or separated from the top:

With the top in decent shape and all the loose braces taken care of, it was time to put a bridge plate in place. I made a general outline of the shape from the broken pieces I had, and made a new plate out of rosewood. Then I made a caul out of plywood of the same shape for the clamps to attach to. This was a fairly large piece to glue, and I didn’t want to take any chances with any part of it not getting fully glued to the top – so I may have gone a little overboard with my clamping situation:

Next I shaped the bridge to fit the new shape of the top. This is a tedious process of attaching some sandpaper over the top, sanding the bridge a bit, remove the sandpaper, check for fit, repeat… repeat…repeat… This is really important, because if the bridge isn’t making full contact with the top it could open the door for it to pull off again, and ain’t nobody got time for that. Once satisfied, I glued it down, drilled string holes into the new bridge plate, and reinstalled bolts and inlays (the bolts weren’t entirely necessary anymore, but since there was already holes in the bridge, might as well use them).

Lastly, I opted to install a JLD Bridge Doctor, which would reinforce the top by deflecting some of the tension of the strings from the top to the tail block. We normally only use these when absolutely necessary (as was this case), but they absolutely work. Since the top of this guitar was so severely compromised and the owner uses heavy gauge strings, I felt it was better safe than sorry.

The final test was to string it up and see if it didn’t completely explode on me. I’m happy to say that it’s holding together nicely. The top is back to it’s proper shape, the bridge isn’t lifting anymore, and it sounds great! Awesome!

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