Professor hits right note in guitar engineering class: Purdue course lets students build, test instruments

Playing guitar seems much more alluring than building one-unless you’re a member of the Instrument Manufacturing and Testing class at Purdue University.

The course is the creation of Mark French, an assistant professor of mechanical engineering technology, who introduced it just last year. It is already striking a major chord with students.

Eighteen are enrolled now, which is as many as the professor can handle, and the waiting list for next spring’s session is full. French is teaching the class in addition to his normal workload and so far can manage it only once a year.

“Guitars are cool,” said French, 43, who is in his third year at the university. “They’re something we all know about.”

The class is offered through Purdue’s College of Technology and meets three times a week for two days of lab work and a lecture. The students are all seniors and pursuing degrees in mechanical or manufacturing engineering technology.

By the end of the course, each will have built a customized acoustic guitar using engineering, woodworking and manufacturing techniques that include computer modeling, drafting and factory-operation skills.

Students are divided into groups in which some work on soundboards while others craft the necks of their guitars. By spring break, French said, they had the production fixtures finished.

They then will assemble their sixstrings, which usually is when the fun starts, said French, recalling students last year wanting to put pinstripes or paint their initials on their creations.

The seriousness resumes when the instruments are measured for build variation. In manufacturing, the aim is to have as little build variation as possible among each product to maintain consistency of quality. Reducing build variation in guitar making is critical to ensure each instrument has the same sound and quality.

French and student Kendall Brubaker last year visited the headquarters of Taylor Guitars in El Cajon, Calif., and spent two days conducting audio testing on roughly 60 acoustic guitars at the factory.

Taylor produces about 300 guitars a day and may incorporate French’s recommen- dations into its manufacturing process, said Dave Hosler, the corporation’s special projects manager for product development.

“He’s using a practical everyday tool to teach a world [students] relate to easily,” Hosler said. “He’s uniquely not stuffy [for an academic] and surprisingly creative in the way he looks at things.”

French and Brubaker wrote a paper on their findings that they presented at the 25th International Modal Analysis Conference in Orlando, Fla., in February. A summary will be published in an upcoming edition of American Lutherie, a quarterly journal for stringed-instrument makers.

Tim Olsen founded the Tacoma, Wash.-based publication in 1972, on the heels of the 1960s music revolution that sustains guitar making today. He estimated there are up to 2,000 enthusiasts seriously engaged in the building, repairing or dealing of custom guitars.

What French is doing-passing the craft to students in a university classroom-is unusual, Olsen said. But it makes sense.

“Guitar making is a great hook into all kinds of practical physics teaching,” he said. “That connects to the interest of young people, because the guitar is so much the instrument of our cultural moment.”

French is a self-described “marginal guitarist” who began building his own about 15 years ago. Self-taught through a book, his productions began to improve after the first five.

As a civil engineer for the U.S. Air Force and an auto manufacturer, French had access to dynamics equipment he used to conduct noise and vibration tests. By the time he arrived at Purdue, he had the technical expertise to show others how to build a guitar.

Materials cost each student about $150, or about how much they would pay for a textbook, French said. The wood is highgrade Western red cedar, maple and ebony, and from the same company that supplies Taylor Guitars.

The students determine the measurements they need for each part and feed them into a computer numerical control router, which cuts the wood to the desired shape and exact specifications.

CNC uses a computer that reads instructions and drives the tool to fabricate components. A mathematical model of the part is designed on the computer, and the tool can cut it to the nearest 1,000th of an inch, which is impossible cutting by hand. Once the pieces are molded, the angles and glue seams need to align perfectly.

The cutting tool cost $8,000 and the students assembled it themselves. French is developing the Mechanical Engineering Technology Acoustics Lab on a shoestring, however, and several companies have donated tools, he said.

Sound considerations make acoustic guitars more difficult to make than their electric brethren. But, this summer, French and other professors will lead a one-week course on how to build a solid-body electric model. Representatives from Taylor as well as Fender Musical Instruments Corp. will participate.

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