[Monster212]

Trussrod Adjustment

When to check the truss rod
The rod needs to be checked whenever you string the guitar, although if you use the same strings - brand and gauge - you can make the checking intervals a little further apart. Also, because wood and metal expand and contract according to temperature and humidity, you may find that the neck shifts according to these factors. Also, if you become aware of buzzes that weren't previously evident, it's a good idea to check the neck.


How to check the truss rod
Rest the curve of the bass bout on the floor, and sight down the neck towards the body, looking along the edge of the fretboard. then flip the guitar over onto the treble bout and repeat the operation. Observe how the line along the edge of the fretboard runs. If it seems to curve so that it bulges out away from the body, the neck has a backbow. If it runs the opposite way, the neck has relief. (For those of you who are familiar with trussrods, I know that there are other conditions that I haven't mentioned, but I haven't got the time to write a book on the subject. I'm just outlining the most common truss rod states.) It may be that you see that the neck is dead straight, of course.
So, to sum up. you have three main neck states:
a) relief
b) backbow
c) dead straight

If the neck is dead straight, and you have no buzzing and you like the way it feels, it's pretty safe to assume that your truss rod is adjusted just right. Most techs try and shoot for a straight neck. Even if you have a little buzzing, if you don't hear it when it's plugged in - assuming that it's an electric, of course - then you can leave it. Not all buzzes will sound through the amp. If it still buzzes when plugged in, then this doesn't necessarily mean that it's the truss rod that requires adjustment. You might find your problem is solved by raising the bridge or bridge saddles. If this doesn't work and you don't eliminate buzzing by adjusting the rod - more on that below - then you may need some attention to the frets.


(The lesson to be learned here is that all the various stages of adjustment - the nut, the bridge, the rod, etc - are interdependent and adjustment of one of these factors on its own may not be sufficient to achieve the set up you're after.)
If the neck has some relief and you're happy with it, then you can leave it alone. However, if the relief is too pronounced, causing a very high action which causes intonation problems when you fret a note, then the neck will need straightening by tightening the trussrod.
If the neck has a backbow, this can cause some of the higher notes to fret out. You may find that when you play say, the B string at fret 5, the string is fouled by the higher frets and the sound of the note isn't clear. The truss rod will then need to be loosened to apply some relief.


Where to adjust the truss rod
This differs from one guitar to another according to brand, model and type. Gibsons have the adjustment end of the rod under a small plate on the headstock. Some Fenders have the business end here as well but with no plate. Others have the adjustment end where the neck joins the body, in which case you have to remove the neck to adjust it and keep on fitting it back and taking it off until the rod is right. I'm not going to deal with such adjustment here. Some acoustics have the adjustment area inside the guitar where the neck joins on. There are also various methods of adjustment. Some rod ends have a screw slot, some a nut, and others a hex slot. So, you'll need a screwdriver, a socket of some sort or a hex key. Obtaining the right hex key can sometimes be a problem, but the right one's out there somewhere!


How to adjust the truss rod
OK - this is the moment you've all been waiting for!
Using the right tool and a well-fitting one as well (you don't want to mess up the slot or nut shoulders!) insert it into the truss rod end.
If you want to apply relief to the neck you loosen the rod by turning the rod end - the nut, slot, whatever - to the left, or anti clockwise.
If you want to straighten the neck and eliminate backbow, tighten the rod end to the right or clockwise.
Remember - "righty tighty"!
Apply a one-eighth turn at a time and sight the neck as described above. If the neck is how you want it - stop! If not, apply another one-eighth turn and sight it again. Repeat until the neck looks right.
If the rod won't shift, don't keep on trying to turn it. Take it to a guitar tech. Similarly, if it squeaks or grates, leave well alone and take it to - you've guessed it! - a tech.
The biggest danger is over tightening. In this case, the worst scenarios are stripped threads on the rod, or even a snapped rod. In such cases, the repair can often be more expensive than buying a new guitar. However, you have been warned! If you're in any doubt about your own competency to do this job, take your guitar to a tech and if you encounter a truss rod that won't co-operate, do the same!
Just use a little care and common sense and you should be OK.