For too many years, too many people have spread too many half-baked ideas about setting up and adjusting guitars. Truss rods are of course frequently implicated. So, at the risk of courting controversy, let’s bust some hoary old truss rod myths.
In case you missed it, also check out Truth About Truss Rods – Part 1 – The basics!
Incorrect or Frequent Adjustment of the Truss Rod Will Damage Your Guitar Neck
This is just not true. Honestly believed by many people and maybe even scaremongering by unscrupulous guitar techs trying to drum up extra business. But here’s a fact you need to know: adjusting your truss rod is easier and safer than making a bacon sandwich. Assuming the truss rod nut moves smoothly and the adjustments we make are not too large or sudden, there is nothing we can do to damage a guitar neck. Neck woods are strong and resilient and surprisingly elastic to these types of forces. As we will see below, guitar necks can comfortably and reversibly handle a lot more force than you can ever apply with a truss rod.
What we can actually damage is the truss rod itself by trying to force a nut that is jammed or already at the end of its range. If a truss rod feels tight, always loosen it before attempting to tighten it. Do not use force to tighten a truss rod! If you can’t adjust the truss rod because the nut is too tight, or won’t tighten at all, then you should bring the guitar to an expert for diagnosis and repair.
Truss Rods Affect the Upper Frets
They do not. For the vast majority of guitars on the market today, the region from the body fret (i.e. the fret over the point where the body and neck meet) to the butt of the neck or finger board is unaffected by the truss rod.
Think about it and it makes perfect sense. On electric guitars the neck is either bolted or glued to another piece of wood (the body). Over the last 6 to 8 frets of most electric guitars, we end up with a combined piece of wood about as thick as it is long, which is impossible for a truss rod to bend. For many acoustic guitars, the neck construction is often such that the neck itself only extends as far as the 14th fret, the end of fingerboard with the highest frets actually extends past the neck joint. As such there is no truss rod or neck to bend past than the 14th fret at all!
Assuming there are no other problems with the guitar neck or frets, this leads us to a simple rule of thumb for eliminating fret buzz:
If you have buzz on the lower frets, closer to the nut, loosen the truss rod to increase the neck relief.
If you have buzz on the highest frets, closest to the body, raise the action at the bridge/saddles to increase string clearance at the end of the neck.
Taking all the Strings off at the Same Time Can Damage a Guitar Neck
This logic behind this myth goes something like this – the truss rod protects the neck from string tension, so removing the strings will expose the neck to an equal but opposite force from the truss rod without the strings to counter it. Thus, the neck is exposed to the same risk without strings as it would be without a truss rod. Except that it’s just not true.
This logic seems good but contains a flaw, an implicit assumption that a guitar neck has no inherent strength or elasticity of its own. But a guitar neck is strong and resilient and does a lot of the work against string tension all by itself. The truss rod is not in fact applying the same size force to the neck that the strings are, but is applying a smaller assisting force.
In addition to it’s inherent strength, guitar necks are actually quite elastic and can comfortably handle more force than strings can apply and quickly return to their initial shape. Bob Taylor of Taylor guitars even compares a guitar neck’s elasticity to springs on a car (see here).
A great example is seen in this video (go to 2m25s) of neck testing in the Fender factory. See how much a bass neck bends under their factory stress test? The neck springs back to shape almost immediately, and if it doesn’t, it’s rejected! There is no risk to the neck at all from these larger forces for short periods of time.
And these online videos by Taylor, Martin, and Fender clearly show the technicians taking all the strings off. Note that Dave Doll, the Martin technician, states explicitly that there is no risk to a guitar neck by taking all the strings off.
Historical note – before Leo Fender introduced the Esquire guitar in 1950, he initially avoided the complication and expense of adding a truss rod to the guitar necks, certain that the necks were strong enough. Those early Esquire necks were indeed strong enough but changes in neck relief due to changes in temperature and humidity were problematic. Gibson and Martin knew this decades before (Gibson patented an adjustable truss rod in 1921, and Martin’s non-adjustable rod reduced the neck relief changes). Indeed, the musicians testing the early Fender instruments demanded an adjustable truss rod, like their Gibson guitars had. Fender’s business partner, George Beauchamp, eventually persuaded him that adjustable truss rods were necessary. Fender’s only ‘mistake’ was making the adjusting nut inaccessible without at least partially unscrewing the guitar neck from the body. As a result, many people have avoided truss rod adjustments on their vintage-style Fender instruments, simply to avoid the hassle.
Necks Should be Left to ‘Settle’ After Truss Rod Adjustments.
It somehow kind of makes sense that wood may take time to find its final position after a truss rod adjustment, we think of wood as somehow being a ‘slow’ material. As a result many people say that a guitar neck needs time to reach it’s final shape after a truss rod adjustment. Some even say the guitar must not be played until the neck has settled.
But in 27 years of adjusting truss rods I have never found this to be an issue. If there is any ‘settling’ of a neck after adjusting, it is rare and a relatively small amount. And remember the Fender factory video above – see the neck immediately recover from the stress test? If the neck can do that, why do we think it takes so long to react to a small truss rod adjustment?
Certainly, there is no reason whatsoever to put the guitar aside and not play it for 24 or 48 hours. I’ve even seen people mention not touching the guitar a week! Why? How could playing a guitar ever do any harm to the guitar neck? Even if the neck did take time to settle, putting your guitar away won’t make the guitar neck ‘settle’ any faster than playing it will!
Besides, as there is nothing to fear from truss rod adjustments there is no need to avoid them. Play your guitar, adjust the neck when it needs it, and keep playing. It’s that simple!
As an example to both this and the previous myth, I recently completely unstrung and removed the neck from my Music Man Silhouette Special. I started by measuring the neck relief and string action. Then I took the stings off, unscrewed the neck from the body, cleaned the fret board, I lightly sanded the back of the neck followed by an oil and wax treatment, and polished the frets. Two hours later (after a lovely dinner with friends) I screwed the neck back on and restrung the instrument with a fresh set of Super Slinkys and re-measured. The neck relief and action were exactly as they had been before I started, no adjustment necessary.
Guitars Play Best with a Straight Neck (i.e. no neck relief).
This is just plain wrong and immediately contradicted by the setup specifications of ALL major instrument manufacturers. The basic fact is this – strings need room to vibrate if we are to avoid unwanted buzz from contact with other frets. The less neck relief we have, and the lower the action is, the more likely this is to happen. A straight neck is usually not optimum.
It is true that some players with good technique and light touch can happily play with no neck relief with little string buzz and prefer to set up their guitars that way. But that is not the case for the majority of players. To suggest otherwise ignores the fact that every player is unique and may need a unique combination of string height and neck relief for them to get the maximum playing comfort and enjoyment from their own guitars. (See my post “Your Own Personal Fret Buzz” for more discussion on this point).
Note that due to their higher action and stiffer strings, your acoustic guitars may play well with less neck relief than your electric guitars might need. Also note that for either type of instrument, a straight neck will result in string height that gradually increases along the neck and may be a little too high over the highest frets. Adding some neck relief and readjusting saddle height will help keep string height a more consistent along the guitar neck.
One Should Never Adjust String Height (Action) with the Truss Rod.
Many people are adamant that doing so flies in the face of years of conventional wisdom and could irreparably damage the guitar neck. But if we look at things calmly and logically, we’ll see that this is nonsense. In fact, Ernie Ball Music Man, highly respected instrument makers in their own right and known for the exceptional quality of their guitar necks, actually recommend doing so.
First, notice that when adjusting the truss rod, the string action will change a little. The change in action measured at the 12th fret will be about the same size as the change in neck relief, and therefore is never more than 0.5mm, usually much less. That’s not a lot of change but is certainly something that players can feel and it can make a difference to playing comfort.
The logic behind Music Man’s advice is this: once we have an instrument tuned and set up the way we want, the nut, bridge, or saddles will not spontaneously change height of their own accord. Therefore, any unwanted change to the action over time can only be due to a change in neck relief (e.g. as the wood reacts to temperature and/or humidity changes). As a truss rod adjustment is how we adjust neck relief, a truss rod adjustment is therefore the correct way to fix any unwanted change in the string action when nothing else has changed.
So, we know that we cannot damage a guitar neck with normal, appropriate truss rod adjustments. And the action will change a little when we do so. It is therefore obvious and logical that there can be no physical risk to your instrument when making small adjustments to string action with a truss rod, if you so wish. The worst that can happen is that you introduce some/more fret buzz, in which case, simply undo the adjustment.
There is a proviso to this – with acoustic guitars, large changes in humidity can effect the shape of the top of the guitar, which can alter the bridge height relative to the neck. Therefore, with unwanted string height changes on acoustic guitars, it’s always a good idea to check that drying/humidifying the instrument is not required before adjusting the truss rod.
(Last edit 10 Jan 2016 – corrected broken video link, and updated a paragraph or two for clarity).