When adjusting the truss rod acoustic guitar, you need to be very careful to avoid damaging your guitar.
Adjusting truss rod electric guitar is much easier, but if not adjusted correctly or if the wrong tools are used, it can cause damage as well. So follow the instructions below carefully.
Before start – Make sure the truss rod nut has enough clearance to be turned with a normal Phillips screwdriver. The most common truss rod nuts are 1/8″ (3.2 mm) but check your guitar, maybe the nut is bigger.
The truss rod tool must have a flat blade to fit in the narrow slot of the truss rod nut. Preferably made of steel, not aluminum or plastic. (If you don’t have a special tool, use a spare screwdriver, but it may damage nut slots.)
How adjust truss rod electric guitar?
First, turn the tuning keys until strings are tuned at a pitch where they will be at rest. If you do not know the exact pitch of every note on your fretboard, then tune all strings up 4 half-steps and back down one octave.
Now, sit down and play all strings open (no frets) and check how many notes are not in tune. It should be as few as possible! If you cannot improve pitch by turning the truss rod nut, stop here. Your guitar neck is probably straight enough. But if the pitch is still off after adjusting the nut, then go to the next step.
To adjust the correct pitch on the string, use a special hex key or screwdriver which fits your truss rod nut slot(usually 5mm or 6 mm), turn it clockwise to make the string lower in pitch. Repeat this for every note which is sharp until you reach the desired pitch. (Turning right decreases the pitch of the string, left increases it.)
If you want to make flat notes sharper, then turn clockwise, the string will go up in pitch. (To decrease flat notes turn anti-clockwise.)
When finished with all strings, tune them up again to the desired pitch and compare the result with the first tuning attempt. If it is still off, repeat the above procedure for every string pair (chord). Note that if you tuned some strings higher than they were before, you must now tune other ones lower than their initial position!
This is because strings on the guitar are tuned in pairs, one higher and the other lower, so they cancel each other’s defects.
If you cannot get it right by adjusting the truss rod alone, then adjust the truss rod along with string height. Set string height at desired height first(usually 1/8″ or 3mm)and check again for pitch off after that, then adjust the neck as above if necessary. Note that adjusting string height will alter action (distance between strings and frets), so be prepared to readjust its position. Action can also be adjusted by changing saddles on the bridge of electric guitars or saddle height on acoustic-electric ones.
Adjusting string height for your playing style is a very important step! This is what makes your guitar play and sing! Too low and you will not get a good tone, too high and the strings will start buzzing. If the truss rod does not solve all problems with pitch, try to adjust string height first.
If nothing helps, then your neck needs to be replaced or set up by a luthier.
If your guitar plays fine when tuned only 4 half-steps down but go out of tune in normal position, then most probably nut slots are very worn(or wrong type used)and you should replace them. Otherwise, the problem will just get worse until something breaks.
After adjusting the truss rod electric guitar it is a good idea to check for correct string height at the saddle.
Note that even if after adjusting the truss rod guitar still goes out of tune, there is usually nothing wrong with the neck, but worn nut or bridge saddle. These parts can be replaced easily and cost very little.
If you do not want to buy new ones, then try filing string slots in nuts or re-cutting string slots in the bridge saddle. Old strings will also make tuning worse, so replace them as well. This may help only for a while until screw holes become too big, but it’s worth trying.
Sometimes after adjusting the truss rod guitar neck becomes too straight and makes a buzzing sound on frets. In that case, you have to shim up the neck a bit at the body end to eliminate the buzz. (There are ways of doing this.) If you have a bolt-on neck guitar, you can always try it with a slightly higher bridge saddle. Bridge saddles on cheap guitars are usually too low for proper intonation, but putting saddle higher will only make the problem worse.
To fine-tune the action of your guitar after adjusting the truss rod and string height, use several thicknesses of cardboard as shims between bridge and strings to lower the height of the latter until buzzing goes away. It is better to adjust bridge height using shims rather than changing bridge saddle height because this way it’s possible to move the saddles up or down without taking them off!
I hope this article will help you avoid problems with your guitar, but if not, then try to learn some things about guitar repairs, for example, how to set up the action.
It’s not hard at all!
And remember that adjusting the truss rod is just one of few steps to achieve the correct pitch. Even the best guitar in the world would play out of tune without proper intonation …
So check it periodically and especially before gigs! It may save your life someday.
Q. Most luthiers will tell you don’t adjust the truss rod unless it’s necessary, but some people say it’s better to adjust the truss rod before string height(action) is set. Who is right?
A. It depends on if neck relief is sufficient for your playing style. If so, then there should not be a problem with adjusting it during the neck joint (gluing) process.
It’s important to remember that neck relief should be adjusted separately from action, that is, if you adjust one, the other will change as well. So don’t compromise either and get your neck and action properly set up according to your needs and taste.
Q. I have adjusted my truss rod and got good results, but after playing for half an hour or so the A-string starts buzzing on frets. Why?
A. Most probably nut slots are worn out, or the wrong type of strings used. You can try to file a new string slot in the nut or re-cut the string slot in the bridge saddle.
It is a good idea to check and adjust nut and saddle height after adjusting the truss rod.
If nothing helps, then you should inspect your neck for other problems such as bad glue jobs or worn frets.
Q. I have already set up my action, now the truss rod seems too stiff even when turned all the way back. What should I do?
A. You need to check your guitar’s neck for straightness. If it is not perfectly straight, then the truss rod will be pulling on one side more than the other and this will affect its tension. Straighten the neck if needed.
You can use a special device or just make a simple jig for this purpose.
Truss rod tension can also be affected by humidity and temperature changes so it is a good idea to retune your guitar after some time.