How to Check Your Guitar’s Neck Relief
Adjusting your guitar’s neck relief (the amount of bow and resistance in the neck) may sound like a scary proposition to the first-timer, but this task is something you can definitely do yourself if you take it slow and work in very small increments.
Most quality guitar manufacturers supply the correct tool for adjusting neck relief specifically because they feel this is a job the player can tackle and often needs to tackle as wood shifts due to seasonal changes in climate, travel, normal aging, and other factors.
If you just don’t feel confident doing this yourself, though, don’t hesitate to take it to a pro; a basic neck adjustment shouldn’t cost and arm and a leg, unless there’s something drastically wrong.
The internal tension applied in a guitar’s neck to counterbalance the natural tension applied by the strings is achieved by a component called a truss rod. This long rod is set into a channel routed under your guitar’s fingerboard.
It’s usually fixed at one end and adjustable at the other (threaded) end with a bolt that you turn to increase or decrease the amount of backward tension the rod applies to the neck (that is, the degree to which it counteracts the string tension).
A straight neck may sound like a good thing in all circumstances, and the idea of bow (or anything other than straight) a very bad thing.
Indeed, many players do prefer a very straight neck, but in certain cases, though, players like to have just a little concave bow in the neck — with the fingerboard curving up if the guitar is lying on its back — to keep the strings from buzzing against the frets when you strum and to provide a natural curvature that matches their vibrational arc when you play.
You never, however, want any back bow (a convex curve in the fingerboard), which definitely produces a lot of fret buzz and other playing difficulties.
The procedure for checking neck relief is simple, and all you need is a capo and a feeler gauge (and even that isn’t absolutely necessary):
Put a capo on your guitar’s neck at the first fret.
Holding the guitar in playing position on your lap, with the body perfectly perpendicular to the floor, use a finger on your right hand (for right-handers) to fret the low-E string up the neck at the fret where the neck joins the body.Credit: Photograph by Dave Hunter
Slip a 0.010-inch feeler gauge into the gap between the bottom of the low-E string and the top of the 8th fret (or whichever fret is half way between the capo and where you’re fretting the string).
Most techniques recommend an average gap of around 0.010 inch, although some playing styles might like a little less, some just a little more. The appropriate gauge should slide in easily between string and fret but without any further gap between them. (If you don’t have any feeler gauges, the average business card usually works for a rough estimate.)
Repeat Steps 2 and 3 with the high-E string.
If you have considerably less or more gap than desired, adjust your truss rod.
Having checked your neck relief, now you can adjust most standard truss rods if necessary. Before doing so, however, always consult your guitar manufacturer’s adjustment instructions, and be aware that some modern truss-rod designs function differently than the norm.
If a gentle quarter or half turn of the truss-rod nut doesn’t seem to produce any results whatsoever, or if the adjustment point is stiff and won’t turn easily, or at all, consult your guitar’s manufacturer before proceeding, or take it to a professional repairperson.
Also, be sure you’re using the correct tool for the job, ideally one supplied by the guitar’s manufacturer, or as per its instructions (there are too many variations to cover them all in detail here).
Before making any truss-rod adjustments, loosen your guitar’s strings until you have removed all significant tension from them, but not so much that they’re entirely slack and floppy. For some guitars with headstock-end adjustments, you may need to remove a truss-rod access cover before proceeding, and you usually need to lift some strings aside to do this.
For some guitars with body-end adjustment nuts, you have to remove the pickguard, or even loosen and lift the neck, as on many bolt-neck Stratocaster-style guitars.
To make adjustments to neck relief, proceed carefully, gently, and slowly, and work in increments of just a quarter turn at a time.
Decrease: To decrease relief in the neck (reduce a concave bow), turn the adjustment point clockwise to tighten the truss rod (as viewed facing the adjustment point).
Increase: To increase relief in the neck (increase concave bow), turn the adjustment point counterclockwise.
If you’re new to truss-rod adjustment and don’t have a handle on how much of a turn achieves what result in your guitar, start with just a quarter turn, then bring the strings back into tune and check the relief again. If that has produced little or no result, de-tension the strings again and go with another quarter turn, or even a half turn this time if there was absolutely no evidence of movement.
Tune up, check again, and proceed accordingly.
Again, if the nut gets either very tight or so loose that it feels about to come off and the adjustment hasn’t yet produced the desired result, or if you find yourself turning more than one and a half or two full turns or so with no apparent result, then STOP! Take it to a professional.