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:
http://terrydownsmusic.com/technotes/MusiciansWorkbook/M_FRIEND.XLS
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:
http://www.cadstd.com/lite.html
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.
I don’t think any of this is “nuts” at all–I think it’s great. Personally, I’m pretty sensitive to the way a nut is cut and the spacing between the strings. Sometimes small differences feel like big differences.
That’s really heavy, Terry!
awesome info
great info, now I can put this to use.
thanks, Neil
This is great! It’ll be a huge help the next time I cut a nut. Very informative video, and easily understood. Very well done Terry. Thank you!
Mark Easton
Very nice … Thanks. I do have a couple of questions for a more automated approach:
1) Could Excel draw the lines based on the calculations (like a line chart) with correction dimension?
2) Or, since there’s only 8 lines, could the be a script/macro that dumps out a post script file from Excel? This way we only need to stay in 1 tool
Thanks again.
Thanks everyone for the kind words.
need2retire,
Fist of all, you have a great nick and I feel the same way!!
1) I can’t imagine how to control any Excel graph to print out as an absolute size.
2) Now there’s an idea. I bet I could write some Visual Basic code inside Excel to create a post script file. That is an awesome idea.
I want to know more about the second sentence concerning slot depth and intonation near the nut? Seemingly unrelated to string spacing but possibly more important?
You don’t need to rely on my experience. Ask folks that work on guitars for a living like mellecaster. The nut slots on most guitars are not cut deep enough. Every nut is unique, and to spend enough time filing the nut slots correctly, would significantly raise the price of the guitar. They get it done quick with taking no risk of buzzing, which results in shallow slots. Tune your guitar and get the intonation set. Now using the tuner, check the pitch of each string played on the 1st fret. It will most likely be sharp. It’s hard to get it perfect without going too deep, but a huge improvement can be made.
Nice post Mr. Downs! Too bad the saddles don’t follow that kind of spacing.
Interesting! Now let’s get out our guitar and just play the thing, huh!