Every day as a repairman I’m asked to “set-up” a guitar. There is an assumption that this statement conveys enough information to successfully complete the job. Unfortunately the request for a “set-up” is only the beginning of a process. Any good repairperson will start by asking questions. How does the guitar work for you now? Do you play with a pick or fingers or both? What grade strings do you like to use? All these factors come into play when making decisions about a “set-up”.
Let’s start by talking about the basics of a set-up. At it’s most rudimentary consists of three elements.
1) Neck relief. Relief is the small amount of bow that needs to be in the neck (yes, I said “bow”). I know a lot of people have the idea that necks are supposed to be straight. That’s just not so. Try picturing in your mind, a vibrating string as viewed from the side. This string travels up and down in an elliptical path from two contact points, the nut and the saddle. It follows that the neck needs to have a similar shape. Most guitars that were built within the last thirty years have an adjustable truss rod. This allows the relief to be controlled at the optimal level.
2) The nut. Located at the head of the neck, the nut’s job is to both space the strings on the fretboard and hold them the correct distance from the frets. If the strings are too close to the frets they will cause open string fretbuzz. If the strings are too high or at varying heights the instrument will be difficult to play. Thus the second aspect of the set-up is to regulate the nut either by lowering the nut slots or shimming (raising) the nut.
3) The saddle. After checking the truss rod and the nut, the final element is the action height. This is the distance between the top of the fret and the bottom of the string at the twelfth fret. The twelfth fret is used because it is the mid-point or “octave” of any fretted instrument. The action height is usually checked on the outside strings only. Once this measurement is known, if a change is desired one needs to double the amount of change and either add or subtract from the saddle height. For example, if the action height is measured at 8/64’’ and the player would like the action height lowered to 6/64’’ -- which is a change of 2/64’’ -- we would need to lower the saddle by 4/64’’ or 1/32’’. This is normally done on the base side of the fretboard.