Tools Tips and Tricks

After accurately tuning the selected string while fretting behind fret 2, release your finger and then measure the cents-off-pitch of the open string.  Then multiply the number of cents off by an amount related to your scale length below.  It’s as easy as that!

The compensation amount (length) per cent-off-pitch:

for 25.5″ scale is .01472″    (This is more accuracy than you need.)

for 24.875″ scale is .01436″

for any other scale length, multiply the 25.5″ compensation amount by your scale length divided by 25.5″.

Example: 25.5″ scale, open Low E is 6¢ flat.  Compensation amount is 6 x .01472 = .08832″, round to .088″ of compensation of the nut toward the first fret.  

Note: As the cents-off increases, the compensation amount per cent decreases, as does the width between frets as you go up the fretboard, however, the decrease is so tiny for the first 10 or 15 cents of the first fret, the difference can be ignored.

Note: Please stand by for a little more detail and exposition of the logic behind this topic.

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Pre-test Measure Nut Compensation Offsets

While the offset length can be calculated, many would like a quick, easy way to get an estimate of offset length. (In either case, the final adjustment of the nut offset will need to be done with pitch measurements.)

Here is a simple tool that you can make!  With it, you can do a temporary string compensation, and then, somewhat accurately, measure the offset. It took me about 10 minutes to make this tool from a regular paper clip!

To use it, find a gauge of the right thickness, that will allow you to slide the tool under a string, almost to the nut, putting just a tiny bit of upward pressure on the string. Then, using your strobe tuner or program, slide the tool to where the open string is in tune with the 2nd or 3rd fret. Then measure the distance from the nut to the approximate centerline of the tool wire. Since this is an estimate, add a little more length, so you won’t come up short.

With this information, you can do most of your offset filing prior to installing the shelf nut on the guitar.

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Using Shims For Nut and Saddle

Guitar techs take pride in making new nuts fairly quickly in preference to using shims. For me, that all changed when working with compensated nuts, and more accurately compensated saddles. If you have substantial time invested, you wouldn’t want to throw your work out just because the slots are a bit low. For other than thin shims, the shim should be glued to the nut or saddle. My rule is to not stack more than 2 unglued thin shims.

I have used shims since my very first $20 guitar (my older sister brought it from Mexico) and I have done setup work on all the instruments I have owned since then. As long as you use materials that are reasonably firm and you maintain good contacting surfaces, you will not damage the sound of the guitar. Don’t use tape or anything with adhesive or paper.

Wood and bone are very desirable for shims, and they are natural to put between the bone nut or saddle and the wood guitar neck. For wood shims, I suggest (don’t laugh) popsicle sticks, tongue depressors, and coffee stirrers. (These are also sold as craft sticks.) They are made of birch, usually Baltic Birch, which is cheap, but also strong and stiff, somewhat comparable to maple. Look for them in your local dollar store.

Trim the stick to approximate width and length and then super-glue it to the bottom of the nut or saddle. Trim off any excess width, and then, as a unit sand the bottom of the wood to the needed height with flat sandpaper, or with a table sander, starting with course sandpaper.

For bone, if you have a band saw, mini saw, or precision saw, cut of a strip of material from a new nut or saddle blank, and then proceed the same as with wood, gluing the smooth surface of the shim to the nut or saddle.

Metal is also desirable for a thin shim. (Don’t use metal so thick that the weight is significant – it could change the tone of the guitar.) I spent very little for a 1/3 sq ft scrap of .003” bronze shim stock at a local bearing supply. (You could also try an electric motor shop.) (.003” is a good thickness to compensate for a few years of wear on the string slots.) It is easily cut with strong scissors.

You can also find scraps of aluminum. I saved a piece of a throw-away aluminum pie tin, and, even though it’s crimped for strength, there is still plenty of flat materiel that measures .0045” thick. I saved another scrap of .006” aluminum from a food container.

Re-filling Nut and String Slots

I have a good solution for re-filling nut slots. When the nut slots on my 2 steel string acoustic guitars became too low, I cut out a .003″ bronze shim to raise the nut action and then I reset the action. After 3 years of playing they were low again. Instead of another shim, I used Marine-Tex white epoxy putty to fill the nut slots. Now 3 more years have gone by and the action is still fine on both guitars!

The product is slow drying – It is best to let it harden aomewhat before applying. I allowed it 2 days to fully harden. The color is very white. You can tint it to match the bone, with a bit of acrylic paint, but the color difference doesn’t show very muchwhen the strings are on. The hardened product is very strong. (I patched a large hole in my camping trailer with it more than 10 years ago, and the patch is still secure.)

To prepare for filling, clean the slots with alcohol or comparable, lightly file all the inside of the slots, then clean again.

These Are The Most Convenient and Easiest Shims

Although guitar techs may disagree, I believe that plastic shims are excellent for nut and saddle shims. The plastic is light-weight, and is harder than wood. You can easily collect a variety of thicknesses of hard clear plastic that you see protecting countless items in your local stores, and cut them to use as shims. The plastic can be cut with large scissors or a paper cutter. Smooth out any rough edges with sandpaper.

Thicknesses mostly range between .010” and .020”, but you can occasionally find one about .006”. Credit cards are usually about .024 to .026”. Don’t use insurance cards and or membership cards that are actually plasticized paper.

Try not to use more than two shims on a nut or saddle, and by all means, never shim a saddle so much that the saddle is not secure in the bridge. After achieving the desired action height, I sometimes take accurate measurements and make a new saddle, or I bond bone material to the bottom of the saddle with superglue and sand off the excess, making a like-new saddle.

Products You Can Buy:

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Locating Fret Buzz

Buzz got you baffled? You can find which frets are buzzing with your volt-ohmmeter.   Setit in resistance mode, connect one probe to the test string between the nut and the tuning machine.  Hold the other probe on the end of a suspect fret, and pick the string firmly.  The VOM will register Open Line for no buzz, less resistance for a bad buzz, and more resistance for a weak buzz.

My pocket-sized digital multimeter works really well for this.

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Hollow Grind

When making a partial shelf nut, I need to file back the nut a little for the stings that are already over-compensated.  In order to keep the top front of the nut as vertical as possible, rather than file a sloped surface, I use a small Dremel grinding stone to make a hollow grind.

You probably notice that my shelf nuts usually have a smoother, continuous appearance, especially compared to Delft’s.  That’s partly because the cut-backs don’t show up well in the (not so sharp) photos.

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String Spacing at the Nut

If you are making a new nut, it’s a good time to consider string spacing.  The most common recommendation for string spacing on steel-stringed guitars is equal distance between the strings. That would give you more distance, center to center, the thicker the strings.

I prefer to space the strings equal distance center-to-center.  This is a matter of personal preference, so I’ll just give my reasons my preference.  

My theoretical reason is that the thickness of the strings doesn’t matter; the fingers are reaching for a position where the center of the string will be.  (The thickness of the fingers might make a difference, though.)

My practical reason is that I like to cover two bass strings with one finger, such as an Em 022000 chord fretted by the first or second finger, leaving the third and forth fingers available to play notes on the higher strings.  I couldn’t do that on a classic style guitar with equal distance between strings. 

I also like adequate space between the treble strings.  On the other hand,if a player had larger fingers, cramping on the bass strings might cause he might prefer equal spacing between the strings.