John Brown

Replacing the Soundboard on a 1977 Martin D-35, PT. 2

After concluding that the damage was so severe that the top could not be restored without compromising the guitar’s sound—not to mention its looks—I began the process of outfitting this fine instrument with a replacement soundboard.

1. Using a custom sanding block to remove old glue and level any raised wood fibers. 2. Referencing the original and replacement top bracing with a thickness caliper. 3. The gently curved blade on this guitar-brace chisel makes it easier to trim and shape the new braces to match the originals. 4. My custom workstation made from a shaped piece of Formica countertop attached to a ShopStand and Guitar Repair Vise from Stew-Mac.

In my previous column, I described how a 1977 D-35 arrived at our shop with a big hole in its Sitka spruce soundboard. After concluding that the damage was so severe that the top could not be restored without compromising the guitar’s sound—not to mention its looks—I began the process of outfitting this fine instrument with a replacement soundboard I’d purchased from Martin more than 10 years ago.

After removing the ebony bridge and mahogany neck, and then separating the original soundboard from the body, I was ready to clean and remove any old glue or raised wood fibers from the kerfing, neck block, and tail block.

I made a leveling sanding block from materials I had laying around the shop. For the platform, I used a long rectangular piece of Corian. First I leveled the 1/2" plank using my thickness sander and then I attached a soft rubber handle. To the bottom of this 26" long custom sanding block, I attached a length of 220-grit Stikit Gold self-adhesive abrasive paper (item #5768 at stewmac.com). This is the perfect grit and material for the job.

To stabilize the body on my workbench, I used a plywood cradle (#5657) and body support blocks (#5656), both of which are replacement parts for StewMac’s TrueChannel routing jig. I’ve discovered that many jigs and tools can be used in other ways than originally intended. I’m sure many of you have come across this and perhaps you’ve adapted tools this way too. Using a gentle back and forth motion, I used the sanding block to square the top surface of the kerfing.

I’m really excited about my new workstation. It consists of a Formica countertop shaped like a dreadnought top that’s attached to the ShopStand and Guitar Repair Vise (#5391). This is just the cat’s meow for freeing up needed work space at my bench. The best part of this workstation is how much easier it makes gluing, clamping, and carving braces.

For starters, the height of the ShopStand is adjustable and that really takes the stress off my back. Also, if you’re looking for a good source of Formica, check out your local businesses that install countertops. The sink cutouts are usually taking up space and collecting dust and the staff is usually more then happy to move them out. The sink cutouts are perfect for band sawing out the work platform, as well as many other uses in my shop.

With a thickness caliper (#5193), I measured the original top braces and then used a guitar-brace chisel (#1629) to trim the braces on Martin’s replacement top to closely match the originals. This chisel has a specially curved blade that makes it easier to carve the smooth curves needed for scalloped braces and tone bars with feathered ends.

Diamond fret levelers (#5259) work well for keeping my chisels sharp in the shop. I do like to finalize the cutting edge with an 8000-grit Japanese water stone, which is available online from both Woodcraft Supply and Luthiers Mercantile International.

Here’s a tip: When working with extremely sharp tools, I often wear a safety glove made of Kevlar, Spectra, and stainless steel to protect my hand and fingers. I know a few too many people who have slipped with a chisel for the first time, causing severe tendon damage followed by surgery. Safety, safety, safety!

With a very busy schedule, it’s hard to make the time to keep chisels sharp. But remember that a dull chisel needs an increase of pushing pressure and that can invite accidents. A well-sharpened edge allows the tool to do the work—a better situation for you.

I hope this column has provided you some enjoyment and invaluable insight into the beginning stages of retopping this 1977 Martin D-35. Looking forward to next month!

Gluing Braces Inside a 1967 B-45-12N

Replacing Saddles on a 1971 Gibson SB 300 Bass

Reviving a 1965 Gibson Firebird

Restoring a 1963 Gibson EB-OF Fuzztone Bass

Resuscitating A Ruined '56 Fender Esquire

Restoring a Prototype Gibson Cello Bass, Pt. 2

Restoring A Prototype Gibson Cello Bass

Restoring the Neck on a 1965 Shoreline Gold Fender Strat

Resurrecting A 1965 Shoreline Gold Fender Strat

Replacing the Soundboard on a 1977 Martin D-35

This 1977 D-35 arrived at our shop with a big hole in its Sitka spruce soundboard and a bag of miscellaneous broken braces and slivers of spruce top wood.

1. A close-up of the violated and damaged 1977 Martin D-35. 2. The anatomy of the original soundboard. 3. Martin’s replacement soundboard. 4. The original top’s finger braces. 5. The finger braces on Martin’s replacement top. 6. Inside view of Martin’s legendary craftsmanship. This ’77 D-35 is extremely clean.

This 1977 D-35 arrived at our shop with a big hole in its Sitka spruce soundboard and a bag of miscellaneous broken braces and slivers of spruce top wood. Of course, I was curious to know what had happened, but I was simply informed that someone had expressed themselves a little too much. The good news was the neck and fretboard showed no signs of damage, nor did the East Indian rosewood back and sides. Clearly this was a guitar worthy of being saved and not just laid to rest or parted out.

For those not familiar with the D-35 or the era it was built in, here’s some background: Martin introduced the D-35 in 1965 and it was the first Martin model with a three-piece back. This design reflected a shortage of Brazilian rosewood that was wide enough to make a two-piece, dreadnought- style back. In addition to the three-piece back, the D-35 included a bound fretboard and black-and-white purfling on the sides adjacent to the binding.

Martin had concerns about the three-piece back’s effect on tone, so as a part of their research, Martin luthiers made a few guitars using variations of the company’s different top and back braces. The builders concluded that using 00 top braces and 000 back braces worked best, and this resulted in the D-35 design we know and enjoy today.

The ’70s were tumultuous times for Frank Martin and the company, even though 1971 came with a record-breaking increase in production. The change from Brazilian to East Indian rosewood didn’t concern the buyers, as Martin’s sales weren’t slowing down. From the success of this boom, Frank Martin reached out and found other financial adventures to pursue, which for the most part never panned out. Towards the end of 1977, Martin employees who worked on the factory floor crafting the instruments went on strike. During this time, Martin’s office and management staff had to step up to those empty work benches and start building guitars.

With its history in mind, I carefully examined this D-35. There are times when an original soundboard can be restored—after warping, cracking, or receiving a mild blow, for example. In the vintage world, you want to preserve the instrument and keep everything original whenever possible. However, after diagnosing the damage, I concluded that the soundboard was too far gone and that the guitar would be much better off with a replacement top.

The first step was to remove the ebony bridge and soften the glue joint of the fretboard extension using Stewart McDonald’s bridge heater and fingerboard iron (item #4607 from stewmac.com). Then I removed the neck by applying steam into the dovetail joint while using the neck joint steamer (item #4059) to soften the glue in the pocket.

At this point, I traced out the top to give me a reference for replacing it later on. Then starting at the dovetail, I removed the top binding using a hair dryer and channel spatula. (Had the original binding not been damaged, I would have used a delicate procedure for removing the soundboard while leaving the binding attached to the rib.) Now with the binding off, I used a razorblade and chisel to separate the soundboard from the sides, while being careful to avoid splintering or loosening the kerfed lining.

I decided to use a replacement soundboard I’d purchased from Martin more than 10 years ago. Looking at the original ’77 top and its newer replacement, I noticed a few obvious differences. The original had the larger rosewood bridge plate that Martin implemented in 1969, whereas the replacement had a smaller but very stout maple bridge plate. The finger braces on the original soundboard are trimmed leaner, and I decided I’d shape the replacement top’s braces to be more like the original. I felt this would help the top respond better to the string vibrations, and not obstruct the glorious tone with a stiff soundboard.

Having taken a very close look at the exterior and interior of this D-35, I believe it exemplifies Martin’s legendary quality. Who knows? Maybe this was the last guitar to be built by the craftsmen in 1977 before they went on strike. Perhaps this was their final statement—a way of showing build quality as it ought to be.

Next month, we’ll discuss attaching the replacement soundboard to the Martin D-35 body.

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.

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.