Neck relief on a guitar is the bend in a guitar neck between the head and body of your guitar. This bow maintains the height between the fretboard and the strings. The truss rod is a metal bar set in a channel in the neck that counteracts and maintains the correct bow.
When I first heard of guitar neck relief, I thought it was referring to a massage or something for a guitar player who had been looking down at his strings too long! As funny as that is, I know I’m not the only one because I’ve had many students ask me similar questions over the years!
When you start digging into the physics of guitar neck relief and truss rods you soon discover why both are essential instrument components. They actually don’t have anything to do with the musician!
If you’re here, I’m assuming that you aren’t sure what guitar neck relief or truss rods do for your guitar either. Let’s clear that up!
What Is Guitar Neck Relief?
Pick up your guitar. If you hold it up straight in front of you, from the head to the body, you should notice a very slight bow in the neck of the guitar. This is guitar neck relief.
See, the tension that strings put on the neck of the guitar is quite great, and this bow helps to keep the strings at a level height from the body to tuning pegs. Without this slight bow in the neck, the strings would sit higher at the neck and body, and almost be touching the frets in the middle of the neck.
That also can explain why the fretboard will feel a bit loose before tuning. So the neck relief helps maintain the height between the fretboard and the strings. If that height was out of line with the strings too much, the strings could press into the fretboard and or frets which would change the intonation of the instrument.
Why Guitar Neck Relief is Important
As we hinted above, neck relief is vital for keeping the strings at the right height above the frets on the neck of your guitar. If that height was out of line with the strings too much, the strings could press into the fretboard and or frets which would change the intonation of the instrument.
Strings that sat too high above the fretboard would be extremely difficult to press down, making the guitar hard to play. If there isn’t enough room between the strings and the frets, you’ll get a lot of buzz as strings contact neighboring frets.
How Much Neck Relief Does my Guitar Need?
There are a lot of factors that determine the optimal neck relief for your guitar. Your guitar’s scale length: Shorter scale length guitars need less relief than longer scale length guitars. The radius of the neck matters too. Even the bridge, string thickness, and tonewood can play a part.
Guitar necks only need a slight relief, and most will vary between 0.012 and 0.008. Anything outside this range is either too much or not enough relief!
It is important that neck relief will change over time or due to environmental conditions. Necks usually need to be adjusted at least every few years based on the environment the guitar is subjected to. Vibration can cause the truss rod to expand or contract, and weather can also cause the truss rod and bridge to warp or swell.
Speaking of a Truss Rod…
What is a Truss Rod?
A truss rod is a piece of metal that’s installed into the base of the neck to keep the neck straight and true. Of course, if your neck is straight and true, the guitar won’t need extra relief! Just kidding!
Truss rods are inserted through a pre-drilled hole that’s created specifically for this function. Many instruments, like banjos, have adjustable truss rods. Most nice guitars have them as well, although cheaper acoustics will not always have one that you can access.
How Does the Guitar Neck Truss Rod Work?
A truss rod, normally made of metal, maintains stability and resists the bowing of the wood when it’s put under tension from the guitar strings and tuners. The rod is mounted to both the body and headstock to maintain equal tension on all points. Thus, the strings are able to sit level across all the frets.
The truss rod prevents the natural curving of the thin neck that deals with quite a bit of tension, especially over time. All guitars have a truss rod installed along the neck to keep its shape straight and true, but not all are adjustable.
Should a Guitar Neck Be Straight or Have Relief?
Ideally, the neck of your guitar is as straight as possible. Due to the tension the strings put on the neck, some playing styles, and the construction of some guitars a straight neck is difficult to achieve and in some cases impossible.
The truss rod will counteract any bowing or curving that might occur over time. Your guitar is probably set up with a certain amount of relief in the neck or fretboard under the fretting fingers.
If your guitar is playing differently than it used to, and you’ve done the normal things like change strings, check tension and tune the guitar, and there is no visible damage you may want to take your instrument to a tech who can measure and adjust your truss rod if needed.
Does Neck Relief Affect Intonation?
Neck relief directly adjusts the height that your strings sit above your fretboard, and thus has a lot to do with the intonation of your guitar. High action can lower your intonation and cause buzzing, while low action can make it harder to play a fast lick. In conclusion
If the action you’re getting from your strings isn’t what you’d expect and you’ve tried everything you know how to do to fix it, it may be time to look at the guitar neck relief.
The Final Note
While the neck of your guitar shouldn’t bow or curve over time, many guitars have a small neck relief that is factory set to make your instrument sound its best. If you notice too much bend, adjusting the truss rod to the desired amount will help keep it straight and true. If you are a beginner you may want to get a professional to adjust it.