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Going Nuts Over Nuts

terry_downsI 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.terry_downs

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21 Responses to “Going Nuts Over Nuts”
  1. Radspin Radspin says:

    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.

  2. Scott Auld Scott Auld says:

    That’s really heavy, Terry!

  3. TubbyTone GTRLUVR says:

    great info, now I can put this to use.
    thanks, Neil

  4. porkadon porkadon says:

    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

  5. need2retire says:

    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.

    • tdowns tdowns says:

      Thanks everyone for the kind words.

      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.

  6. 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?

    • tdowns tdowns says:

      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.

      • Dallas says:

        OK – I thought you were saying that slots cut deep made the guitar sharper “cut too shallow”— but now I get it. Too high a slot equals sharp – what I’ve noticed too. Thanks for the info.

  7. Roli Roli says:

    Nice post Mr. Downs! Too bad the saddles don’t follow that kind of spacing.

  8. Pickalittle Pickalittle says:

    Interesting! Now let’s get out our guitar and just play the thing, huh!

  9. Briguy says:

    Very interesting and informative article. I just this afternoon made a new (bone) nut for both of my 51s. I used the old nut as a spacing layout of the new nut and started the slots with a “razor saw” from my model airplane work. I then begine opening up each slot according to its final size, using nut files from Stew-Mac, beginning with the finest file and moving on thru the correct size until I have made each slot width correct for the string to go in that slot. A tip: I save old wound strings and keep them around to use as flexible “files” to “saw” the slots that will be used for wound strings, once I get them close. That way you not only know you are getting the correct diameter slot (cuz it’s the product of the string itself) but it has a nice rounded bottom. The winding acts as a spiral file and only takes off a bit at a time. Final job is to set the correct depth. I like to depress and hold each string at the 3rd fret and then continue holding it while I depress that sting at the 1st fret and release….depress and release, noting how far the string has to travel to touch the 1st fret wire. I like .003 to .005 gap between string and top of first fret wire. More than that and you will get notes going sharp when you play in the first 2 or 3 frets because the string has too far to “travel” to get to the fret wire and pulls it sharp from the tuning you did when they were open.

  10. Anwar Anwar says:

    Alright! You got a few points there I will keep in mind. Thanks!! So what do you think about aluminum or brass nuts? I think these will offer greater sustain and treble which the tele is kinda known for.

  11. Anwar Anwar says:

    Oh, also I am getting tied up around the nut for chords. I was thinking of widening the spacing a bit. Do you think this advisable?

  12. Briguy says:

    If you mean by “getting tied up” you feel like your fingers are all bunched together then widening the spacing MIGHT help a bit…but only a bit. Be careful! You can’t widen the spacing without moving each E string closer to the edge of the fingerboard. Doing that risks pulling the string right off the FB when you bend or finger vibrato. Not to be rude here but…if you are a relativly new player, that “bunching” will go away as you get more comfortable with those chord forms. If you’ve been playing for more than a year or two then maybe they are close. Either get used to it or have your tech make you a new nut. You were thinking about getting a new bone nut anyway, weren’t you. :)
    Brass nuts: I think they are TOO bright to my liking…but then I play everything pretty clean anyway. If you are a guy who right away cranks in some distortion and hits your tube screamer pedal…you won’t notice any difference.

  13. Cavi Cavi says:

    on the slot depth, how close to the fret is correct?

  14. Briguy says:

    Rats…guess it didn’t post the first time…and it was well thought out too :)
    A good place to start is to do this:
    Depress each string at the third fret and HOLD it down. While holding it, look at and/or measure the height of the string above the first fret. You want about .003 to .005 (that’s thousands of an inch, not metric).
    That will put pretty close.
    You can actually get away with even less than that and your chords in the first three frets will finger nicely and not bend up sharp but you gotta “sneak up” on filing the slots when you are that close. A little too much and we will be discussing how to fill nut slots.
    I heard of a guy who used automotive feeler gauges or the correct thickness for each slot and filed little teeth in the edges of the gauges and used them as nut slot files with pretty good results.
    Ingenious !

    • CJFearn CJFearn says:

      I’ve had good results using a normal piece of computer paper (which my caliper claims is 0.004″) and filing until the paper just won’t fit between the string and the fret without moving the string up a tad with the string held down between the second and third frets. As you say, it does require patience if you don’t want to screw up! But, in addition to keeping the string from fretting sharp, it makes the action much nicer for playing as well.

  15. murrmac123 murrmac123 says:

    I think the “nut slots not cut deep enough” thing needs just a tad of clarification.

    It is true that the vast majority of factory guitars require the action eased by lowering the string slots, but after these slots have been lowered, the nut requires work, namely dressing the top, so that the slots are no longer “deep”.

    The nut slot depth requires to be only just over 50% of the string gauge. Nothing looks worse IMO than a high nut with string slots which resemble the Grand Canyon …

  16. Gu1tarkeith says:

    This is exactly what I have spent the last couple of days searching for. Awesome work. Thanks!

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