A Scalloped Ivory Fingerboard Nut
The Fingerboard Nut, located at the top of the fingerboard, determines string spacing and string height at the first fret (measured from the top of the fret to the bottom of the string). Factory made fingerboard nut slots tend to be on the high side. Due to differing climate conditions, this is done to ensure that the guitar won’t buzz when it reaches its destination.
Common Fingerboard Nut Materials
Bone
- Dense & durable but somewhat inconsistent.
- Less porous bone more desirable.
- White in color.
Fossilized Ivory
- Denser than bone.
- White in color.
Fossilized Walrus Ivory
- Dense and a very good conductor of vibrating energy.
- Increased volume & sustain, better note-to-note clarity & improved tone.
- Varying brown in color.
Tusq®
- Man-made material quickly gaining in popularity for increased volume and sustain.
- White in color.
Graphite
- Popular on electric guitars with tremolos for reduced string binding and breakage.
- Black in color.
Plastic
- Factory equipped on cheap and moderate priced guitars.
- Functional but many are hollow, soft and/or spongy with reduced sustain.
- White in color.
Corian®
- Synthetic material used on many Martin® guitars.
- Density more consistent than bone.
- White in color.
Brass or Aluminum
- Not very common or recommended.
- Brass or Aluminum in color.
Ebony
- Most often seen on earlier instruments.
- Black in color.
Zero Fret
- By duplicating fret material, thought to sound closest to a fretted note, but lacks dampened effect of the finger.
- Color matches frets.
The colors of Bone, Ivory, Fossilized Ivory & Ebony
Fingerboard Nut Height...
The height of the fingerboard nut is a variable measurement. Height can vary with saddle height, string tension and diameter, angle of right hand attack, dynamic range of a player or style of player. The lower the string height the easier it is to barre a chord in the first position, but pull-offs on the first fret can be compromised at too low of height. One method of determining slot height that will take these variables into account is to first adjust the bridge saddle to a desirable height with the strings to be used. With the string pressed to the first fret, measure the string height at the second fret (measure from the top of the fret to the bottom of the string). Multiply the measurement by two. The new measurement will represent the string height at the first fret of the open string.
String Spacing of the Fingerboard Nut...
This spacing performs well but looks uneven in appearance because the spaces become the focal point.
This spacing confuses the left hand with varying spaces to string centers.
This spacing performs well & looks good. It is devised by first spacing the slots at the string centers, then as slot are filed, slightly altering the spacing.
Width/Height of Slots...
The width of the slots (A) are determined by the diameter of the strings. An undersized slot can cause a pinching of the string creating tuning problems. An overly wide nut may cause the string to vibrate in the slot losing volume, balance, tone, clarity & sustain. The slot should follow the shape of the string at the bottom and slightly widen at the sides. The width at the "wings" (B) of the fingerboard nut is roughly half of dimension C, but B may vary to accommodate the taper of the fret ends. Slot height (D) is typically 1/2 the diameter of the widest string.
Slot Angle & Shape...
Typically the top of the fingerboard nut is parallel to the plane of the headstock. The bottom of the string slots repeats this angle with it's edge closest to the fingerboard very pronounced. A poorly shaped edge at this point would cause a loss in volume, balance, tone, clarity & sustain. The edge of the slot closest to the tuners is less pronounced and slightly rounded toward the top of its corresponding tuning roller.