No tube too unusual for Gordon Branch
June 13, 2012
Editor Eric Lundin visited Gordon Branch, the guitarmaker featured on the cover of the June 2011 issue of TPJ, to see what Branch had come up with in the last few months. In addition to a new model, 33 1/3 Degree, made with round tube, Branch had developed a similar model made with tube shaped like an airfoil.
Gordon Branch built his first guitar as a teenager when he longed for an instrument he couldn’t afford. His goal was to build one acoustic guitar for his own use. The goal was ambitious but not outlandish, considering his background. He had attended high school in the late 1970s, when vocational programs were plentiful and rewarding manufacturing jobs were easy to come by. He had the right educational background and the mechanical aptitude.
Setting a goal is one thing, achieving it is something else altogether. It turned out that Branch’s solution to his problem, which involved taking a class from master luthier Ervin Somogyi, presented a new problem for Branch to solve. Like the guitar, the class was too expensive. Branch’s creative streak solved this problem too: He offered to make Somogyi a set of tools for building guitars instead of paying the tuition. Somogyi agreed, and before long Branch was the owner of an acoustic guitar built with his own two hands. He still has it, but 30 years later his focus is less on playing and more on making novel and interesting designs, mainly in metal, often from tube.
Although today he works from a home workshop in the Sierra Nevada mountains of Northern California, Branch got started building guitars decades ago while he was working for a manufacturer in San Francisco. His job provided quite a bit of freedom. He was the only machinist in a facility that employed more than 1,000 people, so he could do some moonlighting without drawing much attention. When he decided to make a guitar body from a billet of aluminum, he stayed late and machined it at work.
This was a huge departure from conventional guitar designs, which use wood for both acoustic and electric models. In addition to being unique, it’s versatile (see Figure 1).
He eventually left that position and went to work for a small machine shop, where he occasionally worked with tube. Anyone who handles tube knows that it rings when struck, and this didn’t escape Branch’s attention. He thought tube’s acoustic properties would work well for a guitar.
“I wanted a totally original design,” Branch said. “I wanted a modern, industrial look, and I thought tubing would get me there. I started coming up with very angular designs, and when I had one finalized, I named it AirTube V.” (See Figure 2.)
Branch’s hunch panned out. The guitar has sound characteristics like no other.
His next design took the tubular concept further, relying on rectangular billets and round tubing. It didn’t develop from a flash of inspiration; it took quite a bit of time to take shape.
“I draw and erase and draw and erase and draw and erase,” Branch said. “Sometimes I hang a half-finished drawing on the wall and wait for inspiration to strike.” It was this process that led to the guitar he named The 331⁄3 Degree (see lead photo). Harking back to the days when vinyl records were the main music medium, the name also is the angle of the aluminum billet at the front of the body. Two aluminum billets, one at the front and one at the back, are connected by horizontal lengths of round tubing.
Through the course of building guitars from unique designs, Branch has applied quite a few things he learned over the years as a machinist. Still, more than 20 years of experience didn’t prepare him for everything. Branch’s career as a luthier has been one of experimenting and problem-solving.
The AirTube V. The AirTube V’s design is elegant and sleek. It has all the features you’d expect to find on a guitar like this—a body, a neck, a bridge to anchor the strings, two pickups (which turn the string’s vibrations into electrical current), and control knobs. However, the AirTube V also has an additional feature, a small panel on the back of the body. This panel gave the welder access to the inside of the billet that serves as the instrument’s body. This is the design feature that made the AirTube V work. Without it, it would have been impossible to assemble. In other words, the guitar is lacking one feature you would expect to find: visible welds.
The 331⁄3 Degree. The 331⁄3 Degree is a different animal altogether. This design didn’t lend itself to hiding the welds, so Branch learned how much work goes into grinding down welds. Because he was going for an aesthetic look on par with AirTube V, Branch had to take the welds down completely by grinding them and polishing, polishing, and polishing some more until the weld area couldn’t be distinguished from the parent material.
He started the work with a power tool, but on occasion he lost control of it and put grind marks where they didn’t belong. Branch soon tired of repairing errant grind marks, so he resorted to doing the rest of the grinding by hand. While he acknowledges that it turned out to be more work than he planned, at least 40 hours, he found that the clean look made all the effort worthwhile.
Airfoil Shape. While browsing through a metal shop, Branch happened to see a length of tube in the shape of an airfoil. He didn’t have any particular plans for using it, but bought a 6-ft. length anyway because he thought it had potential. As he worked up the design for it, he gave a lot of thought to the welds, especially the grinding and polishing process. He wondered if he could eliminate them.
“I looked into dip brazing,” Branch said. “After assembling the instrument, it would be dipped into a salt bath 100 degrees below the melting point of the aluminum, but above the melting point of the flux. The flux would fill in the gaps between the components, bonding them after it cooled.” The big drawback was that Branch would have to make all the holes oversized by 0.010 inch, and that would have left too much to chance. He couldn’t be sure if the instrument would come out straight.
After he decided to design it for gas tungsten arc welding (GTAW) assembly, he still had to figure out how to make two airfoil-shaped holes in the front billets. One of the tube-billet intersections had no weld, so he needed a good fit for a good look. A gap would be unsightly. Making a hole shaped like an airfoil on his mill wouldn’t be a possibility, so once again Branch affirmed the value of hand tools and elbow grease.
“I had to file it by hand,” he said. “I used a grease pencil to mark the tube, then slid it into the opening, looking for the spots where the grease rubbed off.” The patience paid off (see Figure 3).
Off-the-shelf tube comes in an endless variety of shapes—oblong, obround, hexagonal, octagonal, slotted obround, triangular, and on and on. What’s next for Gordon Branch? It’s hard to say, but considering that he plunged right in when he saw the unique airfoil-shaped tube, anything is possible.