Guitar Nut Vertical Angle
Source: Guitar Nut
Adjust Nut String Slots – Existing Nut:
The way that the strings set in their respective string slots is very important. I often see repair mistakes on the nut and it is a very sensative area to get the adjustiments just right.
In our first diagram, at the beginning of this article, you will note that the string is supported by the nut where it meets the backside of the nut or at the beginning of the fretboard. It is very important that the string be supported at the very edge of the nut like this.
Problems that you will find are string slots that are either too big or too small for each string gage. You will also see slots that have been cut with a triangular file. This means that the string wedges on the sides of the slot and does not seat properly.
There are a couple of ways to correctly file string slots. The first is with gaged nut files. These consist of a set of files that range in gage values consisting of the following gages:
0.012″; 0.016″; 0,026″; 0.032″; 0.042″; 0.050″; 0.060″; 0.075″; 0.090″; 0.105″ and 0.120″. These gages will handle most any string gage and a really nice benefit is the bottoms of the filed slots are rounded to fit the string shape.
Another way to file nut slots is with gaged saws. These come in the following gages: 0.030″; 0.025″; 0.020″; 0.015″ and 0.010″. With the gaged saws you do not have quite the versitility that you do with the gaged files, so some of the strings will be in wider slots. Also the slots that are made with saws tend to be flat-bottomed.
What most luthiers do, to provide professional results, is to rough-in the slots with the gaged saws and do the final nut slot shaping with the gaged files. This saves the life of the expensive files and lets you make the first cuts with the saws, which is an easier cut.
Guitar Nut Horizontal Angle
Source: Guitar Nut
If you are adjusting an existing nut, you will want to set the correct string height first of all – or in other words, set the correct slot depth. To do this we will treat the nut as if it were a zero fret condition. So we have to mark the exact height of the fret on the face of the nut.
To do this, what must luthiers do is to keep a sharpened lead wooden pencil in the workshop and sand it in half so that you have a flat bottom with 1/2 the lead left.
Take the pencil and hold it flat on the first few frets and use the point of the pencil to scribe a line on the face of the nut.
Ultimate Guitar Repair Tip: What I have done is to fashion a stick to receive a mat knife blade. I made the stick about 8″ long, 1″ wide and 1/4″ thick with a recess that I routed in the face of the stick to reveive the mat knife blade so it is flush with the bottom of the stick.
I glued the blade in place and treat it as a disposable tool. After all you can sharpen the blade if you desire. This makes a nice sharp scribed line on the face of the nut. You can then rub the line with the side of a lead pencil to make the line more visable.
Now you can take either your gaged fret saws or gaged files and cut each respective slot down to the scribed line.
Be sure to angle your files directly toward each tuning machine post that the string will be wound on. Double check the vertical angle you are filing too, because what you don’t want is for the string to exit the nut without it resting on the very back edge of the nut.
Tags: adjusting a guitar nut, Guitar Nut, guitar nut files, guitar nut slots, guitar string action
