Gluing Braces Inside a 1967 B-45-12N
1. Using tape to determine the size of the gap that needs to be glued. 2. Threading the stem of the trimmed pipette into the brace repair tool. 3. Applying Titebond glue between the top and brace using this specialized tool. 4. The scissor jack and brace repair jack make it much easier to hold and clamp braces. 5. Positioned inside the guitar, a single brace repair jack clamps the upper face brace to the top. 6. The 12-string’s elongated peghead features two triangular pearloid inlays, which look particularly cool under the yellow tint of the aged nitrocellulose lacquer. 7. What a beauty! The restored ’67 Gibson 12-string.
The B-45-12 is a 12-string dreadnought that Gibson first introduced in 1961. During the ’60s, such legends as Gordon Lightfoot, Leo Kottke, and Reverend Gary Davis made history strumming on their B-45-12s onstage and in the studio. Kottke liked the warm sound of the guitar’s mahogany back and sides, and the B-45-12’s adjustable bridge and ebony saddle made for a very playable 12-string. In 1963, Gibson introduced the B-45-12N, with the N indicating a natural finish, as opposed to the standard cherry sunburst on earlier models.
The guitar featured in this month’s column was built in 1967 at Gibson’s factory in Kalamazoo, Michigan. It features a Sitka spruce top, solid mahogany sides and back, a mahogany neck, a Brazilian rosewood fretboard and rectangular bridge, 3-ply celluloid top binding, and single-ply back binding. Other appointments include a tortoise-color pickguard, Kluson Deluxe 6-on-a-plate tuners with white plastic buttons, and a chrome-plated trapeze tailpiece.
This guitar’s owner thought it might have some loose braces and brought it in for me to inspect. If you suspect that an acoustic guitar has loose braces—because you’ve observed structural issues or heard rattling noises—then every brace on the top and back needs to be checked inch by inch.
For the initial test, I like to gently tap on the top and back. Most of the time (but not always), I can hear if there are loose braces lurking inside. Even when acoustic guitars come in for just a basic setup, I like to thoroughly examine them. I’ll automatically inspect the braces by peering through the soundhole with a combo mirror and LED light (item #3225 from stewmac.com).
Other useful tools for examining braces include the telescoping inspection mirror (#0362) and the folding 3-piece inspection mirror (#5124)—a set of reflective acrylic panels you can fold up to get through the soundhole. Once the panels are inside the guitar, you unfold them to create a flat 7 1/2" x 12" viewing surface. Very slick!
Earlier ’60s editions of the B-45-12 had issues with construction. The guitar’s dainty bracing allowed for more tonal projection, but because they had a pin bridge, rather than a trapeze tailpiece, early B-45-12s often pulled apart—especially when tuned to concert pitch.
Luckily for the owner of this guitar, his instrument had a trapeze tailpiece. Once I inspected the braces, I found only a 1" end section of an upper face brace that was loose. Overall, that was a minor repair compared to what it could have been.
I was delighted that this project gave me an opportunity to try out a new tool I’d just purchased from Stew-Mac. Designed by Dan Erlewine, it’s called the brace gluing wedge (#0200). You use this tool to gently shim open the gap under a loose acoustic guitar brace and inject glue right into the gap.
Before using the brace wedge on the B-45-12, I did a dry run and practiced positioning the brace repair jack (#3544). For this repair I also used a scissor jack (#0490)—a fantastic tool that lets you clamp areas that your arm can’t reach when working through the soundhole.
After filling the brace wedge’s pipette with Franklin Titebond glue (#0620) and gently squeezing the bulb to inject the glue into the gap, I set up a single brace jack to clamp everything back together. The final step was to carefully wipe up any remaining glue squeeze-out.
Once the glue had dried, I removed the jack and strung up the Gibson 12-string. Tone is so subjective, but to my ears, this Gibson B-45-12N has an awesome sound with glorious sustain. It was wonderful to get the instrument back into top sonic condition.
John Brown is the inventor of the Fretted/Less bass. He owns and operates Brown’s Guitar Factory, a guitar manufacturing, repair, and restoration facility staffed by a team of talented luthiers. His guitar-tool and accessory designs are used by builders all over the world. Visit brownsguitarfactory.com or email John at firstname.lastname@example.org.