A truss rod is a metal shaft installed in a channel within a guitar neck. It runs the length of the neck, lending stability and making it possible to adjust the curvature of the neck. Over the years guitar builders have experimented with many types of truss rods. Today the two most common are the single-rod design, and the double-expanding design. Which one should you choose?
Single-Style Truss Rods
The single-rod design came first. As the name suggests, it is comprised of a single metal shaft. This shaft is installed in a channel under the fretboard. The channel bows slightly downward in the center, and once in place the rod takes on this bowed shape as well. At one end the rod is anchored to the wood. The other end is fitted with a threaded adjustment nut. As the adjustment nut is tightened the rod is pulled towards a straight position, thereby raising the center of the neck. Warmoth uses this type of truss rod in both our “Vintage Construction” and “Vintage/Modern Construction” necks.
Double-Expanding Truss Rods
The double-expanding truss rod, like those used in Warmoth’s “Modern Construction” necks, is a more modern development. This rod consists of two metal shafts, and unlike the single-style rod, it is installed in a perfectly flat channel. Rather than being anchored to the wood at one end, the two shafts are anchored to each other. The opposite end is fitted with a threaded adjustment nut. As the nut is tightened the rod moves in two directions at once: upwards in the center of the neck and downwards at the ends.
Pros and Cons
Each truss rod design has its own characteristics. The single rod style is lighter and more vintage correct, but requires seasonal adjustment. It also exerts a lot of inward pressure on the wood, which over time can distort a neck. The double expanding rod exerts no inward pressure on the neck wood, and is so stable it rarely needs adjustment after the initial set-up. Its increased mass also eliminates dead spots. To decide which type is right for you, ask yourself what you find more important: a vintage vibe, or superior stability and low maintenance. No matter which you choose, Warmoth has a neck for you.