Because the neck of your guitar is adjustable. It needs adjustment from time to time. It has been made of selected hardwood, and it is kiln-dried to insure proper curing. Consequently, the adjustable truss rod both strengthens the neck and facilitates adjustment of a bowed neck.
Because all guitar necks are subject to great stress as a result of string tension and seasonal change, furthermore, there are times when a neck could take on a slight bow (or warp) or neck hump. This will rarely occur. However, if it does, there is no cause for alarm if you follow the procedure below for proper correction.
Angled Headstock typical of adjustable truss rod location (above)
First of all, loosen all strings (it is not necessary to remove strings from guitar). Pull loose strings to one side so free access to neck adjuster can be gained.
Remove cover (if it has one) so neck adjuster is exposed. Generally it’s an Allen screw or a hex nut.
Sight down the neck from the tuners (as sighting a down the barrel of a rifle) in order to see just how much of a bow or hump the neck has taken. Hold the neck up at eye level and sight along the edge of the fingerboard on both treble and bass sides. It best to place a straight edge on the neck during this process. Most of all, there are special ones made with cut outs for the frets called a Notched Straightedge below.
If neck is bowed, tighten the adjustable truss rod nut clockwise
If neck has hump, loosen the adjustable nut counter-clockwise
Place Allen key or hex wrench on guitar neck adjustment nut and turn very gently (small fractions of a turn at a time). Keep checking the neck as you proceed with each nut turn. Once the neck is straight give the adjustment nut a very slight added turn to compensate for the tension the loose stings will add once they are installed and tuned. TIGHTEN for ” BOW ” and LOOSEN for HUMP.
Special Note: Be careful not to tighten the nut too much ( i. e. when it becomes hard to turn ), because it could result in stripping the threads or perhaps even breaking the truss rod.
Below: see example of a end of the guitar neck Heel or Butt end type-truss rod adjustment
Adjustments at the butt end of the neck
Especially relevant, on certain models of Solid Body Guitars the adjustable truss rod is at the lower end of the fingerboard called the Heel or Butt End. Therefore, the procedure of adjustment on those is same as above, follow the same pattern of correction as outlined. As a result, the rod will straighten.
If there is string buzzing after you are certain the neck has been straightened, locate the fret at the playing position that causes the buzz. Lower the fret by gently tapping with hammer. If necessary, file fret down, level and re-crown it.
The Side Adjust Mechanism
Warmoth Modern Construction guitar necks feature a Gotoh Side Adjust Mechanism*, which allows fine truss rod adjustments without removal of the neck. Initial setup is still accomplished using the main truss rod adjustment nut, but subsequent minor adjustments can be done via a small access hole on the side of the neck. Click the “More Information” link below for instructions on adjusting and resetting your Side Adjust Mechanism.