Going Nuts Over Nuts
I am very picky about how the nuts are cut on my personal guitars as well as others I work on. Most all new guitars from the factory have nuts with shallow string slots, resulting in notes played near the nut being sharp. Most people agree there should be an equal spacing distance between the strings, not equal distance between the centers of the string. When cutting a nut from a blank, some folks use the Stewmac string spacing ruler. It is a great tool and I have used it a number of times. It has spacing slots that proportionally increase in separation along the length of the ruler. This would be ideal if the next bigger string in your set was the same ratio larger than the one before and so on. Here is a plot of the percentage of one string diameter to the next for two string sets. The first data point is the how much larger the 2nd string is to the 1st. The second data point is how much larger the 3rd string is to the 2nd, and so on. Notice the huge variation.
I developed an Excel spreadsheet that will take the following inputs:
- String Diameters (read from the pack)
- Margin from the edge of the nut to the outside edge of strings 1 and 6 (usually 0.120”)
- The nut length (measured with a caliper)
- The fretboard radius (either known or measured)
The spreadsheet will calculate the centerlines of the string spacing so there is equal distance from the edge of one string to the edge of the other. A graph is generated to depict the diameters and spacing It also takes into account the radius of the neck. This improvement in accuracy by taking the radius into account is negligible. I just did it because I could. The spreadsheet is in the Musician’s Workbook downloadable here:
Here is a demo of the spreadsheet.
Once the centerlines are calculated, one can use a Computer Aided Drafting (CAD) program to draw a paper template that can be cut out and glued to the nut for precise cutting. There is a free CAD tool available for download here:
Here is a video demonstrating how to draw the nut template with CadStd.
Here is the template glued to the nut.
A 0.009” fret slot file can be used to begin the slotting process for the most accuracy.
I’m sure most of you think this is overkill, but if the capability exists, why not use it? Happy nut cutting.