The next step in checking and setting up your guitar, is described here. If you missed step one, click the highlighted bold text link below (the second text link).
Step two is how to check the relief in the guitar neck using specialized guitar tools, the ones we use for our guitar repairs in our shop. I am also going to demonstrate for someone who wants to try this at home. The procedure can be performed at home if you are somewhat mechanical and careful. The tool expense is minimal, in fact most folks have the tools at home.
First things first: No matter what you want to do during your guitar setup, you gotta check and adjust neck relief before you go any further. We can’t adjust our truss rod if we can’t check the relief or flatness of our guitar neck. Remember, we are going for flatness First.
The tool on the right side in the third picture is a good ‘old fashioned’ precision straight edge, about 12″-18″ long, and a set of feeler gauges. Don’t underestimate these tools. Many guitar makers, aka, luthiers, still use these tools very successfully.
For testing purposes, as you can see, the guitar maker performs all of the procedures in the normal playing position as noted in the pictures and with the guitar tuned to the pitch the player plays in, whether it be concert pitch or 1/2 step down. Another way of looking at it is, that tuning the guitar to pitch puts the proper amount of tension on the neck, such as when you play it.
Taking a look back at the guitar repairs-setup article #1 it is easy to see the amount of forward and back bow (relief) a guitar neck can develop. The tool with the dial indicator is very accurate. You can see the needle and numbers on the dial, so it is quite easy to look at the exact amount of the measurement. If the needle goes clockwise then it has up-bow, conversely, if the needle goes counter clockwise, we have back-bow.
Using the straight edge in the same guitar position we used with the dial indicator, set the ruler on the fret board as centered as possible, then carefully see if and where there may be light coming from between the frets and the straight edge. If there is light in the middle, you have up-bow. Where ever you see light, obviously there is a gap there, and that is where the feeler gauges come in. Measure the gap between the ruler and the feeler gauge, to determine the amount of bow and what direction to turn the truss rod for “zero” relief. Easier said than done, but not impossible.
The truss-rod is the way to adjust the relief. The direction of the bow in the neck determines what direction to turn the truss rod. Remember, don’ force it, or my next article will have to be about replacing a truss rod! Got any questions? Call me at 1-772-979-2887. Good luck and enjoy. GuitarPlayersCenter.com