Go Nuts!

By John LeVan

A guitar's nut is an important element in determining playability. Here's how to make sure it fits and functions correctly.

Besides the material a guitar's nut is made of and its proper installation, various factors contribute to playability.

All guitar strings pass over the nut, so that often-overlooked piece of bone, plastic, or other material sitting between the fretboard and headstock can really affect a guitar's playability and tone. If not set up properly, the nut can cause issues ranging from string rattle to tuning and intonation problems. Let's examine a nut's essential elements-height, spacing, placement, and tone-and how to work with them to make your guitar play and sound its best.

Nut Setup

Height

For optimal playability, it is imperative that the nut's height be correct. Excessive string height (action) at the first fret can make the guitar very difficult to play and cause the strings to play out of tune. This is because the note bends out of tune if the string has to be pressed down a greater distance than normal to reach the fret. In addition, there is more tension on the string the closer you get to the nut, so you have to press the string harder to get a clean note. To fix this problem, the string slots need to be cut deeper into the nut.

On the other hand, if the action is too low at the first fret, one or more strings will rattle and buzz when you play an open note because they're too close to the first fret. Instead of a complete replacement, the nut can be shimmed by placing bone, plastic, or wood underneath to raise the action to the correct height. This is recommended when you have multiple string slots that have worn down or been cut too deep. Once a nut is shimmed, it is important to adjust the rest of the string slots to the proper depth.

Raising the action of just one or two strings can be accomplished by filling the string slots with bone dust and super glue, then re-cutting them to the proper height. This is only a temporary solution though, because the dust and glue will wear out faster than the nut itself.

Spacing

If the string spacing on the nut is off, the strings will either be too far apart or too close together, and the guitar will be hard to play, especially for finger-and single-note picking. If the spacing is too close to the edge of the fretboard, the strings can roll over the end of the fret-a situation that requires a new nut carved with the proper spacing. Some players prefer to have the spacing customized to suit their playing style. I have experienced this with a guitarist who wanted his sixth string closer to the edge of the fretboard so he could fret it with his thumb. He also wanted the first string farther from the edge, to match his bending technique.

Placement

A nut's placement is critical to the guitar playing in tune. If the nut is too far from or too close to the first fret, the guitar will never play in tune. With more and more factories using CNC (machinery guided by Computerized Numerical Control) to make and match their parts, this isn't much of a problem with most new guitars, and most individual luthiers take great pains to ensure a proper fit as well. However, some entry-level guitars, vintage instruments, and guitars that have been poorly repaired in the past can be improved by moving an improperly placed nut.

Tonal Considerations

The material from which the nut is made will have a dramatic effect on the tone of a guitar. Several different types of materials are commonly used, including plastic, bone, ivory, micarta, brass, and graphite, to mention a few. Plastic is the most common, but it's a soft material that not only wears quickly but also insulates and absorbs tone, so it tends to make a guitar sound thin. Bone is a great material for a nut. It produces a loud, clear sound with excellent sustain on open strings. Ivory also produces a broad dynamic and great sustain, and it sometimes makes the guitar sound warmer. Micarta is a synthetic material that sounds rather strong in the midrange. One drawback to micarta is that it collapses under pressure, which pinches the string in the nut slot, causing tuning problems and string breakage. Brass was popular back in the 1970s, but its often very bright and harsh tone has made it go out of favor.

Plain graphite sounds a little muted to me, but it keeps the strings from binding at the nut. Graphite is used in Tusq-brand products (used by many manufacturers as stock equipment), which tend to sound a little brighter than plain graphite and produce shimmering harmonics. Each of these materials will sound slightly different depending on the overall tone of the guitar. For example, a bright-sounding guitar will benefit from ivory more than bone, and a warm-sounding guitar often sounds better with bone or Tusq, which adds a little brightness. It's important to use the right material for your guitar to get the best tone and sustain.

Care and Maintenance

Fortunately, a few simple bits of maintenance will minimize wear and tear on a guitar's nut. Adding a little bit of graphite to the string slot will help the string slide smoothly through the nut-simply use a mechanical pencil to color in the slots. Regular inspections are also a good preventive measure. Take a look at the slots when you change strings and look for signs of wear, cracks, and chips. Also, nuts are generally cut to match a specific gauge of string, so if you change gauges, the slots should be re-cut by a luthier for a perfect match. This will prevent tuning problems, string rattle, and premature wear of the nut, all caused by the string getting stuck in the slot or moving sideways within the slot.

In general, consistency, inspection, and a little graphite will extend the life of your guitar's nut and defer costly repairs.

This article also appears in Acoustic Guitar, Issue #180