Editor’s Note: It should be noted that the process below is universal for all types of guitars with removable nuts. The images used in this tutorial were taken from Fret MD: Acoustic Guitar Setup and Maintenance, but they still serve to accurately illustrate the processes and ideas that are used to sand down an electric guitar nut. (Also, some electric guitars (hollow bodies for example) have a nut and headstock construction, similar to the images below.)
Sanding Down the Top of the Nut
As a general rule, the top of the nut should be sanded down so that half of the diameter of each string sits above the nut. When strings sits too deeply in the nut slots, over time (due to string friction) they tend to work there way down from tuning, stretching notes, and changing strings. If you file these slots at an in correct angle you can hear a sympathetic buzz and if you file to deep you’ll hear the string vibrating on the first fret.
Sanding Down the Bottom of The Nut
When sanding down the bottom of a nut, the most important thing is to sand slowly, on a flat surface and check the nut often, taking care not to remove any material. your just removing the old glue.
Process for Sanding a Nut Down*:
The process below is the same for sanding down the top, or bottom, of a guitar nut.
1. Loosen your guitar strings and then move them to the sides of the nut. DO NOT cut or completely remove the guitar strings! (You’ll want to be able to replace the nut and put the strings back in the nut slots to check your nu adjustments.)
2. Remove the nut.
3. Draw a line (or Not)
(In general, sanding down a nut involves removing tiny amounts of material, so measurements and drawing lines usually aren’t necessary. More often than not, getting a nut to the right height is a matter of trial and error. Of course, if your nut needs 1mm, or 1/64 in., or more, material taken off, then drawing a line as a guide is recommended.)
4. Using a sanding block, sand the bottom (or top) of the nut until the nut sits at the desired height.
5. Put the nut back into its nest, tune the strings back to pitch and use a feeler gauge to determine whether the nut has been sanded down enough. (If you were sanding the top of the nut, then check to make sure that half the diameter of each string is now sitting above the nut).
6. If your strings are still too high or still sit to deep in the nut, or both, then repeat steps 1 through 5 until your strings are at the right heights.
We used video footage and 3D computer animation to illustrate this concept in Fret MD: Acoustic Guitar Setup and Maintenance.
If, after sanding your nut down, some strings are now too low, find out how to shim up your nut.
* This process is the same for all guitars with a bone or other material you might be using. (e.g. Electric guitars, acoustic guitars, basses etc.)