Sunday, October 18, 2009

Wheat Thresher and Winnower

The wheat crop in Chilakonda has reached maturity. I realized it would be very difficult to thresh all that wheat by hand by beating with sticks and then tossing in winnowing baskets to clean it. Besides beating causes damage to the grain so I decided to build a pedal powered thresher and winnower to do the job.  The project was generously funded by the Friends of Malawi (

After making careful plans I went into town to buy the supplies and materials. The agriculture department provided transportation to the village. We had a pretty good load.

The power units are 2 bicycles - one for each machine. We removed all unnecessary parts.

For the thresher we built a box out of plywood and attached the front and rear wheels of one of the bikes inside to provide the bearings and support for the threshing drum. The sprocket on the rear wheel is also used to drive the drum.

We drilled holes in boards. . .

. . . and bent pieces of heavy wire into a V shape. The ends of these wires were put into the holes in the boards and the ends bent over on the back to hold them in place.

These boards were attached to the wheels with screws. Here I am working with Johanne Banda, the father of David Banda who was adopted by Madonna. He is a skilled carpenter, metal worker, brick layer and general craftsman.

Here is the finished thresher. Later we added a cover over the wheel to keep the wheat from flying all over.

Next was cutting the frame for the winnower. The fan was made by removing the spokes and rims from the bike wheels and screwing on 4 pieces of plywood for fan blades.

The finished winnower.

The women of Chilokonda Wheat project trying out the thresher. It worked better than I expected, taking the grain off the stems very well. The only problem is that a fair amount of straw and a few un-threshed heads end up with the wheat. Some kind of screen needs to be added to reduce that.


Here is the winnower in action. Wheat is poured in at the top and drops down the chute while the fan blows air up the chute taking chaff, dust and straw with it. We found the speed of the fan is to slow so I am having 2 bike sprockets welded together to boost the rpms.
If this project is successful we will build more of these next year. I also want to teach the farmers how to design and build simple machines to make other jobs easier.


Anonymous said...

Great Job Dad! You winnower and thrasher look awesome! It looks like you are doing a lot of great stuff there. -Lili

Rex said...

That is awsome technology! It's great you have the bull now too!


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