Ergonomic Guitar & Bass Neck Design
"What is the ideal string height in your opinion? Ideal fretboard radius? Ideal neck contour?"
— Goran
[UPDATE: Since writing these thoughts, I have invented the Trapezoid Neck Profile, which I now consider far superior to traditional design, in terms of ergonomics and playability. Thoughts on fingerboard configurations below still apply.]
String height above the body is a function of how the neck is set into the body, the body contours, and the selection of bridge hardware. Because tone is a combination of so many interacting and complex factors, I don't subscribe to the point of view that string height above body is a primary variable in determining an instrument's voice. In my opinion, the two important string height considerations are:
1. Comfort of the player's strumming/picking hand — What facilitates technique with the least mechanical and tactile distraction? Play many different instruments (an excuse to spend an hour in a music store) and take notes on what you like and don't.2. Adequate clearance for the guitar pick — How close does the player hold the pick to the finger surface? I've found some hold loosely, some tightly, and some have long fingernails for fingerpicking. To avoid finish scratches or mechanical and tactile distraction, nails or picks should never touch the body of the instrument. Again, play a variety of designs and take notes.
Ideal fretboard radius is determined by the length and thickness of a player's fingers, as those two dimensions determine both reach and "crowding" on a given position. Also, the style of play...as a general rule, smaller fretboard radiuses (10" to 12") facilitate chording, and larger fretboard radiuses (14" to flat) facilitate string bending.
I primarily build compound radius fretboards that begin with 12" at the nut, and gradually flatten to 16" or more by the 24th fret. The logic is string bending is a more likely technique on the upper registers.
One detail that differentiates my fretboards is what I will describe as "tri-compound" radius. Bass (vs. treble) strings (E & A on conventional tuning) describe a larger vibrational arc due to their mass, and thus need additional clearance above the frets in order not to buzz. So, as the radius of the fretboard gradually flattens, it also FALLS AWAY from the string plane under the bass strings, proportional to the mass of the string.
The benefit is lower action without fret buzz, the entire length of the neck.
I sculpt all of my necks by hand, with rasps and files, because to me there is an immediate and visceral difference between sculptural human touch and the "log-like" consistency of a machine-made neck profile. Hand sculpted necks feel organic, alive, like an extension of your palm and inner fingers/thumb.
I use no template, simply feel. Over the years, my left hand has evolved into a highly sensitive evaluator of sculptural profiles. My right hand holds the tool, and my left constantly feels and reports the changing nuances.
If you were to model the contour I personally prefer, it would be something like:
1. Modified "D" profile — Slightly flattened along the spine, opposite the fretboard.2. Asymetrical — With the slimmer side between the player's thumb and index finger.
3. Tapering — From thinner near the nut to the thickness of the body at the neck joint, in a logarithmic progression.
4. Neck thickness — Determined by player preference, the flexibility of the neck materials and gauge of the strings.
A completed neck built to all the criteria above will allow your fretting hand, with some practice, to "know" its fret position simply by touch. Also, ergonomic benefits are such that all of these principles follow the natural mechanical leverage points of the human hand, resulting in reduced stresses and extended playing time for a given amount of caloric effort.
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