Trapezoidal Neck Profile (Ergonomics)

EDITOR'S NOTE: This article is part of a series exploring aspects of the Trapezoidal Neck Profile including: construction details, design theory, and ergonomics. Patent pending, John Vereb, patent attorney. Contact me if you're interested in licensing the design.

Trapezoidal Neck Profile is unique in the world of instrument design because of how it interacts with the human hand. The function of the Trapezoid Neck Profile is to create distinct planar surfaces, which may be symmetrical or asymmetrical. You might discover — as I did — your hand prefers it to a rounded surface, two locations in particular:

• index finger-to-palm joint
• thumb

In both classical and pinch grip playing positions, these two anatomical features are primarily responsible for controlling and orienting the hand in relation to the neck, allowing the fingers to smoothly perform fretting tasks.

Orchid (bass) was the first instrument to employ this design. It is equally effective on guitar, and I have incorporated it into current builds including: Skele lightweight guitar, Dove ergonomic guitar and Cupid semi-hollowbody guitar.

Pinch Grip

This is likely the most common playing position, with the neck cradled between Metacarpophalangeal joint and thumb. Back of the neck often rests against the fleshy "web" connection between thumb and palm as the thumb floats upward or over the top of the fingerboard to fret bass strings.

In studying how the Metacarpophalangeal joint interacts with conventional neck designs, I realized convex surfaces actually prevent the fingers from penetrating deeper into the fingerboard, which is one motive for assuming this playing position. Players seem to constantly seek less index finger resistance and greater overall finger reach.

By removing material — making the lower surface of the neck a flat plane (or even concave) — the neck comfortably facilitiates finger reach. Perceptually, the neck feels like a super slim profile.

PHOTO: Pinch grip playing position. Note lower neck plane contact with index finger Proximal phalange bone as Metacarpophalangeal joint "floats" just behind junction of lower and back neck planes.

PHOTO: As the hand shifts closer to the fingerboard for single note runs, pull-offs, hammer-ons, bends or vibrato the Metacarpophalangeal joint acts as a pivot against the lower neck plane as the wrist rotates.

Classical Grip

Musicians who are formally trained or who utilize complex barre chords, will typically play with the thumb centered on the back of the neck. This allows the fingers to rapidly transition chord forms.

Although conventional curved neck profiles offer highly variable leverage options against the fingerboard, my experiments indicate that is actually less comfortable than leveraging against a planar surface. I believe the reason for this is curved surfaces seem to require more fine motor effort from thumb muscles to stabilize the hand: Abductor pollicis brevis, Flexor pollicis brevis and Opponens pollicis.

After adapting to leveraging against a planar surface, playing a conventional rounded neck by comparison feels awkwardly like attempting to "balance" — that is how I would describe the experience.

I notice my fretting hand fatigues more rapidly when playing a conventional curved neck. One possible explanation is I have been building TNP necks much thicker than I would normally, because the reduced material on the lower planar surface makes the neck "feel" smaller in regards to fingerboard access. A neck .625" or .75" thick (or greater) has both structural advantages as well as leverage advantages, possibly because our hands are engineered by evolution to grasp weight bearing branches with great strength.

It is easy to simulate this experience by "fretting" on your forearm. Place your thumb against your inside forearm bone (Radius) near the elbow and "fret" a barre chord on your outer forearm bone (Ulna). Then place your thumb against your palm and "fret" the back of your hand. Your experience may vary, but I find it requires considerably less hand strength to "fret" on my forearm.

PHOTO: Thumb leveraging against planar surface as fingers form chord.

PHOTO: Note relaxed wrist position.

PHOTO: "Thumb strip" planar surface extends into body. Continued relaxed wrist position.

Video

Video is an invaluable tool for evaluating ergonomic interactions. Having studied the information above, take a fresh look at Monster's performance:

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Unported License

Comments

[Rick Canton]

Excellent and informative post Rick, great work!

[Rick Toone]

Mats — Dove is a guitar with Trapezoidal Neck Profile as well as fanned frets (compensating bridge). No issues that I've discovered. In fact, this combination is my personal favorite for current instruments, and will appear on a prototype acoustic guitar I'm building.

I like your idea of retrofitting an existing instrument with a replacement neck. It would be a great experiment because it would allow you to compare and contrast using an instrument you are comfortable and familiar with.

Drop me an email via my website, and let's talk.

[Mats]

Hmmm.
Very interesting. Indeed. Great info!
Wonder what bass maker Dingwall thinks of this. It would be proven quite efficient on basses with fanned frets, don't you think? Or... maybe the other way around? Making it harder?

Are you making any headless bolt on replacement ones? ;-)

I am for one, a person who thinks about things in the long run, fatigue over time. So it's VERY interesting.

The other day I was at a private showing of an acoustic luthier who lives in Switzerland, builds there, but travels to Sweden from time to time (a Swede but lives in Switzerland, please take notice, those are NOT the same countries!) :-) and he had this 4 string tenor guitars with him as well as his excellent mandolins. (www.runessonguitars.com) Now, those tenor guitars (banjo style necks only on a small guitar body) actually had a TRIANGULAR back neck profile, but more so a regular triangle one than a trapezoid like yours. I found it quite intriguing to play on those, despite I can hardly play any banjo style licks or riffs. I took a look at it's neck and wondered why he didn't build guitars with that, and he went on a rant why one shouldn't do this or that. (RollEyes)

/mats

[Monster]

The neck profile initially felt strange picking up and holding the instrument, and I found myself trying to keep my thumb on the middle of the flat surface. But this became natural when my focus shifted to playing.

The next time I thought about it was when I noticed the absence of soreness and fatigue after hours of playing.