Rice University engineering students play key role in realizing guitarists’ idea
Guitar players are finicky, and so are guitars. But when they’re in harmony, there’s magic.
All of the moving parts need to be in place for music to flow unfettered from the fingertips. For many players, that includes a part not of the guitar but sometimes essential to it: The humble capo, a clamp-like device that acts as a sixth finger across the strings.
A class of Rice University freshmen heard some months ago of a capo problem vexing a couple of players and decided to help them out. A team of students has been working to design a new capo that won’t block players from making certain chords without cramping their fingers.
The students’ attempt to build a better capo was inspired by Rice trustee John Jaggers ’73, managing general partner of Dallas venture capital firm Sevin Rosen Funds. In his spare time, Jaggers plays in an acoustic duo with his friend and fellow picker Matthew Carroll. Knowing from experience how well Rice students are trained to think about such issues, Jaggers approached engineering educators at the Oshman Engineering Design Kitchen (OEDK) to see if his idea struck a chord.
Jaggers said he and Carroll started talking about capos and decided changes were in order.
“I’ve been fairly involved in Rice and a big believer in the OEDK,” Jaggers said. “I thought, ‘Wow, this is a mechanical design challenge.’” He noted that he and Carroll are not mechanical engineers. “And frankly, we don’t have a lot of time to sit around designing capos. So I thought this might be a great project,” he said.
The team of A.J. Fenton, Eric Stone, Lisa Sampson, Nicki Chamberlain-Simon and Amber Wang took four months this spring to design and build a series of prototypes that flatten out the capo, sweeping the mechanical elements back and out of the way of flying fingers while retaining all the qualities good commercial capos offer: versatility, speed of placement and the convenience of being able to clip it onto the headstock when not needed.
Few think about all the problems the guitar poses for a capo maker. The device acts as the barre, taking the place of the index finger that spans the neck in a barre chord and depressing the strings just enough to create solid contact with the frets but not so much as to throw the tones off-pitch. That lets a player change the key of a song to match one’s vocal range without changing the basic chord shapes.
The capo also has to be forgiving enough to accommodate a variety of guitar necks, which not only change from guitar to guitar, but also along the neck of a single guitar. Finally, it had better not dig into the woodwork.
“Sometimes capos hurt,” the guitar-playing Fenton said as he demonstrated a commercial unit that juts out perpendicularly from the neck. “When you play this F major 7, it presses against your index finger and it’s quite uncomfortable, especially if you want to wrap your thumb all the way around.”
“Most people figure out how to make do and curse a little bit while they play, but it’s pretty awkward,” Jaggers added.
“There are a lot of nuances we didn’t think about before we started, like the curvature of the guitar neck or the materials we had available,” Wang said. “Every single part of the prototype we had to make ourselves. So we had to be creative.”
The students’ final prototype has a two-piece, spring-loaded plastic framework created on a 3-D printer with a hard rubber strip that contacts and gently clamps the strings. While it’s not yet perfect – the capo has to be placed just so – the teammates feel they’ve come a long way in four months toward the guitarists’ goal.
They expect the capo project will continue next year, perhaps with a new team of students to work with advisers Ann Saterbak, a professor in the practice of engineering education, and Matthew Wettergreen, a lecturer in engineering.