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Have Duct Tape, Will Travel PUBLIC ACCESS

One Young Engineer has Turned Simple Materials into Life-Changing Tools.

[+] Author Notes

Associate Editor.

Mechanical Engineering 127(06), 40-41 (Jun 01, 2005) (2 pages) doi:10.1115/1.2005-JUN-4

This article discusses how Amy Smith, a mechanical engineer at the Massachusetts Institute of Technology in Cambridge, has turned simple materials into life-changing tools. One of the first was developing a new type of grain mill that could revolutionize the lives of women in the Third World. A motor-driven mill can accomplish the same task in just a couple of minutes, but motorized mills are difficult to come by and expensive to maintain. Smith realized that coming up with a simpler, cheaper mill would be a boon for many families. Often in underdeveloped areas, this grinding must be done by hand, with women crushing the kernels between a rock or mortar and a flat stone or bowl. Smith’s group has developed a clamp for controlling intravenous fluid that could help nurses care for more patients during an epidemic.

Advertisers like to make us think that our possessions tell the story of who we are. In the case of Amy Smith, there might be some truth in that idea. Just take a look at her computer case.

Smith, a mechanical engineer at the Massachusetts Institute of Technology in Cambridge, carries around her titanium Macintosh lap top in an envelope made from foam rubber and duct tape. "It's perfect," Smith said, "because most of the time you want to put your laptop in your backpack, but if you put it in a store-bought case, it won't fit." Not only is her duct-tape computer case functional, but it's fashionable: gray, like her laptop, and sporting an Apple sticker.

This marriage of humble material and brilliant design has caught the attention of foundations and institutions. Most recently, the John D. and Catherine T. MacArthur Foundation awarded Smith one of its prestigious MacArthur Fellowships, the so-called genius award. Many who have received the award in previous years specialized in high-tech applications-Tim Berners-Lee, who devised the World Wide Web, or Naomi Leonard of Princeton University, who also won a MacArthur Fellowship last year for her work on autonomous underwater vehicles. Smith, by contrast, is applying her design expertise to de vising inexpensive solutions to pressing needs in the developing world.

In January, in the aftermath of winning the MacArthur Fellowship, Smith took a trip to the Caribbean. But in stead of a much-needed rest—Smith admits to putting in 80 hours a week at work—she spent the month in rural Haiti. It was a chance to set up three rural gardens and work on some irrigation projects. She also saw the completion of a prototype grain mill that could revolutionize life in remote corners of the Third World.

"I've always been motivated to work in a way that has a larger benefits," Smith said, "and I like engineering and design." In the 1980s, when Smith attended MIT as an undergraduate, she saw engineering as a field that wasn't attuned to serving the greater goood. The focus, she said, was on defens and automotive application.

She decided to make break from that world. After Smith graduated from MIT in 1984, she put her convictions to the test by joining the Peace Corps. As a volunteer in Botswana, she began teaching mathematics, English, and science to junior high school students.

"I learned a lot, especially in the first six months," Smith said. "But while I really enjoyed the teaching, it made me realize that I really enjoy problem-solving. And it is problem- solving to try to figure out how to get people to understand things, but I began to see that engineering would be fun to do in that setting."

Smith signed on for a second two-year stint in the Peace Corps, this time as an agricultural extension agent. "I coordinated the regional bee-keeping program for my district," Smith said. "There were a lot of things that we needed that we didn't have. We needed smokers, so we looked at some smokers, made a few tweaks in the design, and had local craftsmen make them." She also designed, among other things, a hand- cranking audio cassette rewinder out of an eggbeater.

The mill developed by Amy Smith crushes grain with rotating blades. Aerodynamic forces push the flour through the opening in the faceplate.

Grahic Jump LocationThe mill developed by Amy Smith crushes grain with rotating blades. Aerodynamic forces push the flour through the opening in the faceplate.

Not the Next Great Widget

After four years in Botswana, Smith came home to the United States and began graduate studies at MIT. It was 1990, and the culture at the engineering school was in flux. "I remember when I joined the Peace Corps, there were many people who were concerned about how that was going to look on my resume," Smith said.

By the time she returned to the U.S., that was no longer the case. What's more, the emphasis on campus had begun to shift from defense projects to more consumer-oriented items. But Smith was less interested in coming up with the next great widget and more in designing ways to help solve real problems affecting millions, even billions, of people.

Smith found projects in her masters and Ph.D. program that matched her ambition. One of the first was developing a new type of grain mill that could revolutionize the lives of women in the Third World.

Grain—be it millet, maize, or wheat—is a staple in most diets. To increase their shelf life and to make them easier to cook, many grains are ground into flour. This flour can be baked into bread or served as porridge, depending on the culture.

Often in underdeveloped areas, this grinding must be done by hand, with women crushing the kernels between a rock or mortar and a flat stone or bowl. It's a hard job, physically demanding, and can take an hour to make four pounds of flour.

A motor-driven mill can accomplish the same task in just a couple of minutes, but motorized mills are difficult to come by and expensive to maintain. Smith realized that coming up with a simpler, cheaper mill would be a boon for many families.

Three basic kinds of grain mills have developed over time. Grain can be compressed and sheared between two sets of rollers. Since the distance between the rollers establishes the fineness of the flour, this kind of mill requires expensive machining and alignment. Another familiar type of mill crushes the grain between two sets of plates. The mill plates or stones are heavy and costiy, and must be replaced periodically.

The third type of mill uses a series of rotating blades or hammers to crunch grains. Once the particle size is reduced sufficiently, the flour passes through a fine mesh screen and is collected. Smith saw mills of this sort while traveling through Zimbabwe, but many of them weren't working—their screens were broken, enabling partially ground grains to pass through. The screens can't be made locally, and so are almost impossible to replace.

Could a hammer mill be built that didn't rely on screens? Working from a design first proposed by Carl Bielenberg of Appropriate Technology International of Washington, D.C., Smith developed a mill that used blowing air to separate the flour from the grain. "My mill separates things using aerodynamic properties," Smith said. "You don't have a fine—fine in the sense of delicate—part which can get destroyed in the process. It's more rugged." Using a fan inside the grinding chamber, the air stream is just powerful enough to carry the pulverized grain through a chute, while leaving the rest to be ground further.

"The mill also separates the product into two sizes," Smith said. "This means you don't have to sift if you want to separate the flour from the grits. That's something that I didn't realize would be important until I went into the field." The people who tested it told Smith it wasn't a bug, but a feature.

The mill is still in the field-testing phase, but Smith envisions that a final design will be ready by next year. Then, she hopes, it will be built all over the world. "Ideally, the technology disseminates on its own," she said. "It has a competitive advantage."

Smith and her students at MIT have taken on other projects, too. They have developed a water-testing kit that costs $20 to make, rather than the $1,000 for conventional kits. A device to control the chlorination in a Central American water supply system was cobbled together from parts of a toilet tank. And Smith's group developed a clamp for controlling intravenous fluid that could help nurses care for more patients during an epidemic.

Local men examine the cornmeal produced by the improved hammermill during field tests conducted in Haiti earlier this year.

Grahic Jump LocationLocal men examine the cornmeal produced by the improved hammermill during field tests conducted in Haiti earlier this year.

And then there's the duct tape. After getting compliments on her laptop case, Smith and some friends put to gether a duct tape design competition for MIT students and local childers. There are classes on how to make wallet and roses out of the stuff. The best designs-a dragon, say or a suit of armor-get prizes: roll of duct type.

"We spend three hours on a Saturday making things out of duct type," Smith said, "MIT is just full of wacky people who like doing this stuff."

It's that kind of wackiness that can change the world.

Copyright © 2005 by ASME
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