Repair And Restoration
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Warped x-brace on Gibson L-3
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Warped x-brace on Gibson L-3
I watched the Guild F-20 video (https://dev.loothgroup.com/groups/repair-and-restoration/forum/topic/cracker-x-braces-on-guild-f20/#post-60310) with great interest since I’ve been working on a Gibson L-3 with a similar problem.
A little back story – The original repair request was to address a small pickguard crack on the sound hole side. After peeking inside, I saw 5 loose brace ends on the treble side. Still a pretty standard repair I thought as I started gluing brace ends in the lower bout, working my way up. Until I got to the tip on the X brace under the sound hole, everything was going fine. The X brace tip was so warped that it didn’t even come close to touching the top even with significant pressure. I tried using a brace jack to gently push on the brace with a piece of wet paper towel over the brace for a day to see if it would move, but it didn’t budge. I then tried hydrating the whole guitar, followed by soaking the brace with the wet paper towel again, and it still didn’t move.
At that point the customer was contacted, and the only two options available within the budget were to leave it as is or fit a spruce shim under the brace to make up the gap. Since the customer had recently purchased this guitar and wanted it in good playing condition, he went for the shim option.
I decided it would save time if I used a 3d printer to make a shim that was the correct length, width, and taper since its easier to iterate with printed plastic than wood. That decision had the added benefit of giving me a model I could use to duplicate the shim in spruce. Once I had a printed shim that fit correctly, I used double stick tape to attach a piece of spruce to it, and ran it through my small thickness sander. That gave me a nice duplicate of my printed shim.
I glued the shim in using a brace jack and cam clamp as usual. The repair seems solid, and is reversible in the future if someone wants to go to the trouble of replacing that brace.
I’ve been left wondering several things though. Why did the brace ends only come loose on one side of this guitar, and why did the end of the X brace become so warped it couldn’t be glued back into place? One factor may be that the brace ends on this guitar are not tucked into the kerfed lining so it was easier for them to pop loose. Another factor may be – pure speculation here – that the shrinkage of the pickguard warped the top, pushing it downward right above the X brace end causing it pop loose years ago, and it slowly warped over a long period of time.
These kind of repair problems certainly keep things interesting. Comments and insights welcome –
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2 Replies
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I think severe shrinkage. The top, sides and bottom are thin and the braces are thick and everything shrink/swells at differing rates. In my young career, I’m dealing with very severe shrinking and straightening guitars is the bulk of the business. The average humidity here is 28%. Humidity can go from 75% to 4 % in a day. Instruments brought from areas that average more then 45% come here and change over night. A guitar showing severe changes came in last week and is the poster child of shrinking severity so far. The bottom braces were let into the lining and the guitar shrank so much that the brace ends actually blew through the sides and separated the binding. The brace ends stuck through a 16th of an inch in the worse spots. I hadn’t seen this yet. So far, most of my time in the shop has been educating myself in techniques to repair twists, shrink damage and warpage. It’s been fun actually.
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That move of 3D printing the taper you want and running it through the sander to make a copy just blew my mind! Thanks for sharing Dave!
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