Guitar Nut: Fine Tune It For Optimum Performance and String Action

Guitar Nut - Adjust For Optimum Performance

Nut Too High Or Too Low? Find Out How To Adjust Right Here

Georgia Luthier Supply
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Guitar Nuts -Their Purpose

The Guitar Nut is a bone, ivory, plastic or wood strip of material that separates the fingerboard from the guitar headstock. It is usually about 3/16" to 1/4" in width and holds the strings off the fingerboard at a proper height to prevent strings from buzzing on the top of the first fret or the first few frets.

Tools Needed For This Repair:

    1/8" Wood Chisel
    120 Grit Sandpaper
    400 Grit Sandpaper
    Oversized Bone Nut Blank

    Feeler Gage

    Plastic Tipped Hammer

    Thin-Kerfed Back Saw

    Knife File

Tools To Made The Job Easier But Not Necessary

    Gauged Guiter Nut Files

    Finger Planes
    Block Plane(s)
    Dremel Router tool + attachments
Compression Truss Rod

Zero Fret Installation

A very small percentage of guitars (usually electric guitar models), have what is called a "zero fret" installed directly behind the nut. We will not talk about these installations in this article as they are out of context with a guitar nut discussion.

The Guitar Nut also plays an extremely important role in how you guitar plays in the lower positions - from the first to the 5th frets. Ever try to play an F Major bar chord on a guitar with high strings at the nut. Ouch! Cramps in your fingers!

Read on an learn how to adjust your guitar nut action just right and you will have a guitar that is a pleasure to play.

Preperation For Work:

Make sure you have access to a solid work bench or work surface of the proper height. For shorter people this will be 32" to 34" and for taller people, 36" is standard.

Place a padded surface down on the work bench that is soft and free of any debris, such as wood chips, metal shaving or any other foreign objects. I prefer to use an old Rug or something like that.

Have access to a very good lighting source that is adjustable and you can aim it at your work.

How to Measure Correct String Height

Just think of the guitar nut as the "first fret" of your guitar, similar to the zero fret installations shown in photo above.

Unless the strings are obscenely high at your guitar nut, utilize this method for measuring your correct string height:

    Place a padded support beneath the neck at the 3rd or 4th fret. If you want to make your own support we have plans for a great Neck Support Jig.
    Before you do anything, make sure you don't have any high frets that will throw you off with this method. Check for high frets by placing a 3 or 4" straight edge over all the frets that it will span, say from the first to the 4th fret. Check all over and if you can find any high frets, where the straight edge rocks, adjust as necessary. This is also called a Fret Rocker. If you wish to make your own, we have plans for a Fret Rocker.
    Rock the straightedge back and forth to make sure it does not use a high fret as a fulcrum point. Also look at each fret to make sure you do not have a low fret. Note: however we are only concerned with the first few frets for this article.
    Take into account for any Neck Relief that you may have on your guitar. If you do have a high fret go to my article on Fret Leveling.
    Place a screw-down type capo, such as a Shubb or Victor, directly behind the first fret and tighten it until you start to get a clear tone from a picked string. Do not clamp it so tight to mash it down to the fingerboard as this will give you an unreliable measurement.
    Now take a Feeler Gage and precisely measure the distance from the top of the fingerboard to the bottom of the 1st and 6th strings directly in front of the first fret. Write this measurement down.
    OK, now if it is determined that we have to do quite a bit of lowering on the nut, it is best to take the strings off the guitar. So let's do that right now.
    The theory here is that this distance from the top of the fingerboard to the bottom of the strings grooves should be the same or very slightly more than the height of your frets above the fingerboard.
Scribe Your String Groove Measurement on the Nut
    Now place your feeler gage on top of the fingerboard right next to the nut. If your fingerboard has a radius, make sure the feeler gage conforms to this arch and is tightly fit to the top of the fingerboard.
    Take a sharp marking knife or very sharp pencil and trace a line directly onto the back of the guitar nut marking the top of the feeler gage onto the nut.
Time for Filing

You now have to make a decision. That decision is what type of tool to use for cutting the grooves deeper in the guitar nut. On lesser expensive guitars I would recommend a standard Knife File.

The problem with this file is that you have to work it back and forth a bit in the larger 5th and 6th string groove to keep the strings from binding and when used for the (3) treble strings you will find the slots are cut too wide, but workable.

Some do-it-yourselfers have used Feeler Gages that they filed teeth on the bottom. This will do in a pinch, but make sure you round the bottom of the gage plates first, as you do not want a flat-bottomed string slot.

Another option can ge a set of Torch Tip Cleaning Files. These are a bit hard to work with but they are gaged and round and will do in a pinch, plus you can buy them really cheap.

    A far better method is to use gauged knife files which are make if different widths and allow you to use smaller file for the treble strings and match the string gages quite closely for a nice comfortable fit. The concern for this method is cost as these units are quite costly for a one-time event.
    If you plan on doing this on more than one guitar, go for it a purchase them. They are available at Stewart McDonald, which handles a vast amount of specialty tools for guitar building and repair.

Before you start your filing on the grooves, take note of these tips to give you the best installation.

    Notice in the photo below how the file is tilted downward roughly following the angle of the peghead and not straight, following the fingerboard. This is very important because we want to make sure the string rests on the backside or fingerboard side of the nut and not in the middle or on the front of it. This would cause intonation problems. You would also have problems obtaining a clear note when an open string is played.
    Also, and this if very important, notice how the string channel for each string on the guitar nut points toward the tuning post from the backside of the nut? Since you likely have grooves started in your nut already, they should be set up like this for you. But do refer the to drawing I make of a peghead and string arrangement below.
Nut Files

Strings Are Angled Across The Nut To Tuners


The drawing below shows the correlation between filing angle and string angle and the importance place on having the string rest on the backside of the nut.

Nut Drawing Side View

String Angle Versus Filing/Channel Angle

Filing of Guitar Nut

Using the above procedure, file the groove down on the guitar nut to within about 1/32" or less of the line you scribed on the nut. Be careful not to go below this line as you will ruin your nut and have to make a new one. Do this with each groove and use the appropriate gage file or knife files as necessary.

If you had to file your channels deeply into the nut you now have to take some of the nut top surface off. A general rule, at least for the bass strings is that slightly less that half of the string should protrude above the guitar nut groove. In other words the string shouldn't be buried in the nut. The best tool for taking down the nut top surface is a sanding stick.

I will discuss how to make sanding sticks in another section of the site, but basically it is garnet sandpaper glued to a smooth stick of wood with feathering disc adhesive, making it replaceable. Use Grit #120 to hog down the guitar nut. Be careful and check often as you go. When you get close to the desired height, switch to a 220 grit and finish up with 400 wet, dry and #000 steel wool to polish the nut.

String-up your guitar and test the new string height. If you took down the top of your nut as described above, you should be able to make final adjustments with the strings on and tuned up. Just lift up on the string gently and move it to the adjacent channel. Make a few strokes with the nut file and retry.