In the meantime, Thom cranked out a quick "winnower", made with a variable speed motor from a used range hood. The winnower will eventually be integrated into the device and powered by hand, but this quick set up let us try different fan speeds to see what worked best to separate the lighter chaff from the heavier millet.
Here in Ohio, Thom seems like a pretty smart guy, despite what his sweatshirt says...
With the prototype up and running (quite noisily), and the winnower working, we dropped a few scoops of millet into the hopper and turned the crank. (sorry for the bad camera work...)
The object of the thresher is to extract the millet from its glume, while not crushing the grains. As you can see in the before (top) and after (bottom) pictures below, we did pretty well for the first test!
By this time, sunlight was fading fast, and we were fresh out of doughnuts...both good reasons to call it a day (along with the hallucinations caused by fumes from the kerosene heater). The last image below is a side by side comparison between the original Leary thresher, and the refined prototype. We have reduced the size and weight considerably, and will be able to send this over to Mali in a suitcase rather than a crate. This will save time, money and running the risk of it getting lost in shipment.
Next Steps:
- integrate winnower
- wrap floating roller with rubber to reduce grain breakage
- incorporate sprockets and chain
- build stable base
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