Tuesday, 24 May 2011

What do I do with a truss rod?

I have had many people ask me what the truss rod is for in a guitar.  While learning about the truss rod myself a few years ago, I came across a little post which I printed off and kept in my little 'how to' book that I made while I was a guitar tech at a music store.  Here it is!

(It all started, of course, with someone asking how to adjust a truss rod.)
XxStratxx wrote:
> I will tell you what everybody told me, dont mess with the rod,
> its like holy and if you dont have a doctoral degree you will
> ruin your life for ever and ever, (sic)

Paul Guy replied:

Dear Leo, who art in heaven...
If thou be Pure in Heart and Pious in Spirit, locate thou the Holy Truss Rod Nut - remove thou the Holy Truss Rod Cover if there is one. Take thou now thine instrument in praying position, this being the position in which thou dost hold the instrument to perform the Holy Rites of Rock'N'Roll, or whatever you happen to be into. Press thou now reverently thine E-string down upon the first fret and the highest fret simultaneously and inspect thou the Holy Gap, which hereinafter shall be named the Holy Relief, between the bottom of the string and the top of the seventh and eighth frets. At the seventh and eighth frets shalt thou look, and not anywhere else, save that thou mayest also look at the sixth and ninth frets, but there isn't really much point. At the other frets shalt thou not look, save for if you really want to.
Let There Be Light between the string and the fret, the light shall be in the amount of approximately one and one half times the sixtyfourth part of one inch, or about half a millimeter. Note thou well, howsoever, that not all Guitars are created equal and that some Guitars will need a little more and some Guitars may get away with a little less.
Shouldst the Holy Truss Rod require adjustment thou art constrained to obtain the correct Holy Implement, which hereinafter shall be named the Holy Truss Rod Wrench, or in certain cases the Holy Truss Rod Key, or in other cases, like older Fenders, The Holy Bloody Great Screwdriver. Verily, use of any other implement is heresy and may ruin thy Holy Truss Rod Nut for ever and ever, with the result that thy Holy Truss Rod will not perform its Holy Miracle of keeping the neck straight.
Thou canst do no damage by loosening the Holy Truss Rod Nut a bit in an anticlockwise direction if the string is touching the seventh and eighth frets, or if the Holy Relief is insufficient. If the Holy Relief is too large mayest thou gently turn the Holy Truss Rod Nut one quarter of a revolution or thereabouts in a clockwise direction. Check thou again the Holy Relief at the seventh and eighth frets and if it continueth to be too large have another bash. Shouldst the Holy Truss Rod Nut require large amounts of adjustment to achieve the required effect, something is FUBAR and thou shalt make Confession to thy parish Reverend Luthier for absolution.
(A very few Holy Truss Rods operate in the reverse direction, thusly, a clockwise rotation doth cause the Holy Truss Rod to add more Holy Relief, and an anticlockwise rotation doth cause the Holy Relief to diminish. Lo, these shalt thou operate with thy left hand. Or with thy right if thou dost feel like it.)
Now, if dost thou encounter resistance to thy ministrations that seemeth abnormal (if thou canst not easily adjust the Holy Truss Rod Nut without giving it some stick), or if thy ministrations seemeth not to have the prayed-for effect, or if the Holy Truss Rod shouldst make any rude noises, shalt thou cease and desist forthwith and immediately. Thereafter thou shalt entrust, without unseemly delay, thine Instrument to thy parish Reverend Luthier for His blessings and ministration of Holy Relief.
Thus is it written in the Book of Orville, whose Prophets at the Temple of Gibson were blessed with this wisdom many moons ago, when the faithful did wail that their necks did warp and bend, and that the ends of their fingers did hurt like merry hell. And thus it is,

Now this may all seem a little silly but lots of useful things can be learned from this little post
1.  You don't want a neck that is perfectly straight - every guitar needs a little relief. 
2.  To Measure the relief, put a capo on the first fret, and press down on the 17th fret, and measure on the 8th fret with some feeler gauges (I know that the post says that you should press on the last fret but I feel like I can be a little more exact if I use the 17th and measure over the 8th - because the 17th fret is 8 frets from the 8th fret).
3.  You will probably want .010" ish of relief for an electric, .012" - .015" for an acoustic
4.  To add relief, generally an counter clockwise adjustment is necessary
5.  Always use the right tool for the job.  To strip out a truss rod nut is almost unforgivable.
6.  If you have any questions, ask someone!


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