This innovation is subtle, but adds significant comfort and playability to the geometry of a fretboard.
When we chord on the lower registers of a neck, we typically want the neck to be as narrow as possible. That allows our hand to encircle the neck and our fingers deeper reach into the fretboard.
However that changes as we move up the fretboard, into higher registers. Chords give way to scales, melodic runs and bends, often beginning around the 5th fret and growing in importance approaching the 12th fret (octave) and above.
Heaviest treble string bends — and bass string bends if they are employed — occur most often near the octave. Bass string bends gradually decrease in importance in registers above the octave, as strings become difficult to reach and tonally less interesting to our ears. Treble string bends become push bends (not pull bends) above the octave, as our fingers develop tremendous leverage near the neck heel.
One frustrating issue often encountered in conventional fretboard geometry is string run out during bends and vibrato near the octave. String run out is the inevitable result of a fretboard edge that is parallel to the outer string from nut to heel. The problem is compounded by the midpoint of the string, which requires least force to bend. It is common for strings to drop over the edge of the frets, resulting in dead notes and loss of signal.
One solution I've devised is called Fretboard Flare and simply adds approximately 1/8" to the width of the neck — usually treble string side — at the octave.
As you can see from the above photograph of the neck I sent Ola Strandberg for the FUZZ Guitar Festival in Sweden, resulting treble string bending surface area is nearly doubled in width at that point. Note also the width of the neck in critical fretting registers is almost completely unaffected. During play, your hand will appreciate the bending space but not notice changes in chord registers.
On the baritone guitar currently in progress, I am exploring this feature intently.