Every guitarist should learn to do truss rod adjustments for him or herself.  There really isn't much danger if you use caution.  Most new guitars come with a wrench for you to use for that purpose.  If you are buying a guitar and it doesn't come with one, ask the salesman for one.  They're usually glad to give you one for free.

The truss rod adjusts the amount of bow or "relief" in the neck.  The neck should have a little bit of relief and not be perfectly flat unless it's a nylon string classical guitar.  When you pick, pluck, or strum a string, the maximum movement is in the middle between the nut & saddle of the guitar.  Depending on your playing style, you may want more or less relief.

In my Tips 82 & 102, I mentioned this stuff but it doesn't hurt repeating...
a.) If the string buzzes when you fret on the bottom 6 frets, the truss rod may be too tight.

b.) High action up by the sound hole end of the neck may mean that the truss rod is too loose and/or the bridge/saddle setup is too high.
c.) Check the concaveness of the neck. With your left index finger, push down on the Bass E string on the first fret like you're playing a F. With your right index finger, push down on the Bass E string at the 12th fret like you're playing a high E. Now look between the bottom of the Bass E string and the top of the 6th fret. You should be able to see a very slight gap. Just enough to see some light.  If you can't see any light and/or the string is touching the fret, the truss rod is too tight.  If there's a larger gap than the thickness of a business card or match book cover, the truss rod may be too loose for you.
d.)  If the relief of the neck checks out alright using step "c.", but the strings are uncomfortably high, DON'T try to lower them by tightening the truss rod.  You might break it.  In some cases the problem is best fixed by lowering the height of the saddle instead.

The main cautions to observe when adjusting the truss rod are...
a.) Make small adjustments each time.  (1/8th turn)
b.) Look at the results of each adjustment before turning again.  If the opposite is happening than the desired effect, you're probably turning it the wrong way (see below).   If it's going the right way, don't go too far.
c.) Be patient.  It may take overnight for the full result of the adjustment to show up.
d.) Don't apply excessive force.  If the nut doesn't turn with a reasonable amount of force, you could break the rod.  This is very expensive to repair!

Now finally : )
Whether the nut for the truss rod is at the tuner end of the neck or in the sound hole, it is tightened to lower the string clearance "relief" by turning clockwise when you are facing the adjustment nut.  Turn counterclockwise to increase the string clearance.  Remember, 1/8 turn!  If the nut is at the tuner end of the neck, there is a small cover to remove first.

As usual, if you have any problems or questions until you learn - go see a pro!

If you have old Martins like mine or a nylon string , there's probably no adjustable truss rod at all.  Mine have never given me any problems but if these necks go out, you'll need to see a repairman or send it to the company.

Gman ( o )==#

 

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