Truss Rods….The Straight Info!
Hey all!!! So NAMM has come and gone, and our people had a great couple days in Anaheim, meeting suppliers new and old. The trip was a success and all I can say is to keep your eyes open on new arrivals this year to hopefully see the introduction of some exciting new products!
Anyway…trussrods….. This subject comes up every once in a while as to what they are, what they do and why we need them. For those of you who are only building kits, you will probably only ever see the adjustable end of a trussrod…and not the entire mechanical unit. For those who have delved into building necks, or removing fretboards, you will be more familiar with these interesting devices.
So let’s go back into stringed instrument history. Since 99% of stringed instruments are made of wood, we have to look at what happens over time on a stringed instrument. For those of you familiar, violins violas, cellos and upright basses have been around for hundreds of years and typically have these heavy, straight grained maple necks. The reason for that is to counter the pressure put on the headstock by the strings. With the advent of classical guitars which were originally strung with gut strings, the pressure on the headstock became an item of interest for builders. Luckily, gut and nylon create only a fraction of the pressure on the headstock that steel strings do. For that reason, classical guitars are typically not built with trussrods although some builders may use certain materials for rods built into the neck to help keep them straight. When Martin and Stauffer originally started building steel string acoustic instruments, they too started with no truss rods, but began building in rods to help counter the pull of the strings. In 1928, Gibson Patented the first adjustable truss rod despite the idea of one had been floating around since about 1908.
When you look at a guitar from the side, you can see the strings anchored at the bridge, bend over the bridge saddle(s), along the neck, over the nut and then get wound onto varying tuners. When we tighten or tension these strings to bring them to a certain pitch (tuning) we place a certain amount of pull on the headstock, which will attempt to pull it upward from the body. This bend is what we call relief. All pretty obvious. On a classical guitar, you may have somewhere around 65 pounds of pull forward, on steel stringed instruments you could easily reach 200 pounds of pressure and on an electric bass, you could have 250 pounds. If the neck is built properly, it won’t break, but it will bend…especially over time (imaging holding your arm straight out from your side and trying to maintain that position holding 200 pounds….) Reinforcing rods can be used to help counter that pull, but really, you want an adjustable truss rod which you can correct this bend (or relief) depending on the strings, wood or season. When you tighten the trussrod, it will force the neck in the opposite way of this pull so you can setup the guitar to play easily and properly. Setting up the guitar is another subject, but let’s just say, a good setup will rely heavily on a properly adjusted trussrod.
If you check our website (or come into the Solo Store) you will find several truss rod variations and reinforcement rods as well. Most ‘vintage’ guitars used single action trussrods, which are single metal rods with an anchor at one end and an adjusting screw at the other. Typically they were installed in a slightly curved slot which caused the neck to counter the pull of the strings when tightened, and allowed the neck to relax when loosened.
Some time ago, someone came up with the double action truss rod. It’s not clear when they appeared in what I’ve found, but I remember them becoming popular in the later 90’s (someone correct me if they know). The double action truss rod consists of 2 rods connected at one end and with an adjusting screw at the other. These rods are installed in a flat slot and allow you to adjust the relief of the neck in either direction. Despite them being a bit heavier I prefer the double action myself….I feel that it gives me a bit more control over what the neck is doing or will do.
Both the single and the double action rods can have their adjusting screw at the body end or the neck end. There are arguments as to which way is better, although I have not found a difference in the necks I have made.
So now that I just opened that door….’the necks I have made’. In my opinion, the most important facet of neck design for any guitar is the grain of the wood. I mentioned early stringed instruments and their heavier maple necks. Yup, maple is hard and straight and is difficult to bend, but the grain orientation in that neck is very important. The best and most stable necks are made from quarter-sawn wood. When you look at the end of the neck, the grain runs up and down (perpendicular to the fretboard). Flat sawn necks (where the grain runs sideways or parallel to the fretboard) are often prettier, but are much more prone to warping. The best way to describe this is to take any longer piece of wood that is square (like a 2 x 2)….it will be much easier to bend in one direction than in the other….this is due to grain orientation.
A very well-known builder in the US used to offer guarantees on his necks if they were quarter sawn, but not if they were figured or flat sawn. The reason I bring this up is that truss rods are an ‘aid’ to keeping a neck straight or to adjust the relief….they are not the ‘solution’.
We could write a whole lot more on this subject, but I hope that this might explain a bit about truss rods for you. Check the website at sologuitars.com and take a look at the selection of trussrods and neck reinforcement rods, and feel free to talk to one of our trained customer service people if you have more questions. Also stay tuned…we are going to try implementing some video blogs, to demonstrate some of the cool tools we offer! Cheers until next time!!
