Inventor Designs Low-Cost Machinery for Third World Farmers

Allen Dong has completed half a dozen designs for farmers in the poorest areas of the world.

By Kathryn PhillipsJun 1, 1992 5:00 AM


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Allen Dong can look at a wooden paddle, a bicycle pump, or a kitchen grain mill and see an array of tools invisible to most people. A lot of inventing has to do with picturing, or imagination, Dong says. It also has to do with being flexible and not seeing an object for what it is but for what it can be.

Sometimes the object has the potential to feed an African village. Dong, a part-time irrigation specialist at the University of California at Davis, uses his spare time to invent low-tech, low-cost machinery with high value for Third World farmers. Since 1983 Dong has completed half a dozen designs, including a vacuum packer built around an inexpensive bicycle pump, a hand-operated soybean thresher that uses a wooden paddle, and a hoe whose blade Dong has creatively filed to make it grab and remove weeds more efficiently. For each invention Dong has eschewed patent rights--and the money such rights would bring--and placed the design in the public domain. He has freely distributed design blueprints through magazines and newspapers from Bangladesh to the Philippines.

The people that need them the most are the poorest people in the world, Dong says of his designs. I don’t feel it’s right for me to become wealthy off them.

One of the inventions Dong lists as his most significant is a rice huller. In the United States the typical rice huller is at least the size of a small building. It relies on a roller system, reminiscent of those on old-fashioned washing machines, to strip the fibrous coat from rice grains to make them edible. The machine is fast and efficient; it’s also pricey, costing a minimum of a few thousand dollars. That’s more money than a typical farmer struggling to survive on a small plot in Africa or Southeast Asia can ever hope to save. Many such farmers hull rice by pounding it with a stick--a slow, tedious, and arduous task.

Dong decided to try to ease that task by inventing a low-tech, affordable rice huller. At first he planned to make something that was essentially a smaller version of the giant mechanical hullers. But he abandoned that idea when the price tag for his working prototype climbed to a few hundred dollars, still out of range for a village farmer or collective. Then serendipity and imagination began to work. He happened to have a kitchen grain mill set up, and it led him in a new direction. These mills are normally used to make flour from rice, buckwheat, or millet grains. Cranking the mill’s handle causes two parallel disks--made of metal or stone--to push against each other, smashing the grain trapped in between. I was just scanning, looking at different things, Dong recalls. I looked at that mill and saw that it has two parallel plates. After that everything else came into play.

Dong found that if he replaced one of the disks with a handmade rubber disk, the remaining stone or metal disk would push the unhulled rice against the rubber one, and the grain would slide out of the hull. The rubber has enough flexibility to allow the grain to slip out of the hull but not pulverize it into flour, Dong says.

Grain mills are sold in hardware stores and markets around the world, satisfying Dong’s demand that his inventions be made from easy-to- get materials. He made the rubber disk in his prototype from natural rubber, which is also widely available and inexpensive in many Third World countries. The final cost for materials: about $70. That’s affordable enough for a village collective, and the gadget is speedy enough to hull 30 pounds of rice in an hour.

Using simple, off-the-shelf materials makes Dong’s design process look deceptively easy. In reality, it takes an average of two to three years for him to complete a project. But the effort is well worth it. Since 1989 Dong has received about 400 letters from people in the Third World who have read about his rice huller and want copies of the design. One of the first requests came from a Tanzanian toolmaker who later sent Dong a photo of the huller in action. For the idealistic inventor, the evidence that his work was making a difference provoked strong emotions. I was happy, he remembers. I was crying.

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