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Refresher on truss rod and action adjustment


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I have been adjusting the 3 piece maple neck on my SG and the bridge to get

the lowest action I can and have done some reading up on it and found this in a search.


I lifted this from a post by Chanman.


Neck Relief: Use a straight edge to determine if a truss rod adjustment is needed. If the neck is bowed, there will be a space under the middle of the straight edge where the neck does not touch the straight edge. If the neck is "backbowed," the frets will touch in the middle of the straight edge.

NOTE: A slightly bowed neck is ideal for most playing styles. A perfectly straight neck generally requires higher string action than a slightly bowed neck in order to minimize string buzz at the higher frets. Repairmen describe this as giving the neck some "relief" to allow for string vibration. The amount of relief necessary varies with playing styles, however. A perfectly straight neck may be fine for a very light picking style. If your neck has only a slight bow, you may not want to make any adjustments to the truss rod.


I like to start with a perfectly straight neck. If I can't get the neck straight, then that indicates other possible problems, such as high frets (frets being pushed out of their slots), low or worn frets, or variations in the fretboard itself, Many older guitars have a "bump" in the fingerboard over the neck block, for example. All of these problems are fixable, but require an advanced level of repair experience.



Truss Rod: (if necessary). First remove the truss rod cover. If the neck has too much of a bow, then the truss rod should be tightened with a clockwise turn of the nut. For a clockwise turn, the arm of the nut driver should start on the treble side of the fingerboard and move toward the bass side. Don't turn the nut more than a quarter of a turn at a time. For a backbowed neck, the truss rod should be loosened with a counterclockwise turn of the nut. When the neck is as straight as you can get it, then back off about a quarter of a turn for "relief."


String Height. With the small ruler on top of the fret, measure the distance to the bottom of the string. (You can also use a feeler gauge for these measurments.)

The string height at the 1st fret will determine if the nut slots have been cut to the proper depth. If the nut slots need to be deepened or filled in, that's a job for a pro with the proper tools.


The string height at the 12th fret will determine whether the saddle should be raised or lowered.


Gibson Electric String Heights:


1st fret- treble side - 1/64"

1st fret- bass side - 2/64"

12th fret- treble side - 3/64"

12th fret - bass side - 5/64"

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Gibson guitars are built well enough that you should not be afraid of making a little truss rod

adjustment if you think it is needed or you would like to experiment a little. I started out by straigtening

my neck and then backing it off while checking and adjusting the bridge and taking the strings down until they buzz

and then going from there. When it comes to the nut I leave that to a professional so far.

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