Truss Rod Soundhole Wrenches
All modern electric and acoustic guitars have truss rods inlayed in their necks. Truss rods were developed over 60 years ago to help reinforce guitar necks and keep them straight. Over time due to environmental conditions, guitar necks can warp or bow. The truss rod helps correct this natural tendency. Basically it's a rod that is inlayed down the center of the guitar neck. When pressure is applied to the truss rod, tightening the truss rod, the truss rod bends inside the neck forcing the neck to bend with it. Loosening or tightening the truss rod will bend the neck in the proper direction to keep it straight. Generally speaking, the straighter the neck the more comfortable the guitar is to play.
Truss rods come in all different shapes and sizes, so do their access points. They have all different types of ends. The most common ends can be adjusted with screwdrivers, allen wrenches, and nut drivers. Some truss rods can be access through the truss where the fretboard ends. Others can be accessed at the bottom of the neck where the neck and body meet. Still other odd truss rods must be accessed through a back panel on the back of the guitar.
That is why there is no all-purpose truss rod adjustment tool. You will need a kit of truss rod tools if you plan on adjust many different guitars. All modern acoustic guitars have truss rods. Martin was one of the last to adopt this technology. They didn't start putting truss rods in all of their guitars until the 80s. I know it's hard to believe isn't it? Unlike on electric guitars, acoustic guitars' truss rod access points can be inside the guitar. Acoustic guitars with access point at the bottom of the neck are inside the guitar. Most acoustic truss rods with this type of access points require an allen wrench to adjust. It is extremely difficult to adjust these truss rods with a straight ball end wrench because you have to stick it down in the sound hole. That's where the soundhole truss rod wrench comes in handy. It is basically a ball end hex wrench bent half way down into a 90-degree angle. The angled shaft fits down into the soundhole while the handle sticks up out of it. This makes it not only easier to find the end of the truss rod, but it is much easier to tighten the truss rod with the angled wrench. If you don't want to pay top dollar for some specialty wrench, all you have to do is buy a standard ball end wrench, heat it up, and bend it. That works just the same!
Soundhole wrenches are amazing tools. If you have tried to adjust one of these truss rods without an angled wrench, you know how difficult it is. If you work on acoustic guitars, I strongly advise you getting a set of soundhole truss rod wrenches. If you don't want to buy a set, you should at least bend yourself one. Once you have used one of these wrenches, you will always reach for one when you are ready to give your acoustic a tune up. If you would like more information about how to adjust your guitar truss rod, please see my how to adjust your guitar truss rod article.