Small Scale Thresher

Tool Concept


This small thresher was built mostly from scrap lumber and metal stock I could obtain in my local hardware store. I do not have a welder so used a threaded rod, lock washers, and nuts to assemble the threshing bars.
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I do not have a welder so used a threaded rod, lock washers, and nuts to assemble the threshing bars. I was able to thresh and completely winnow 6.5kg of rye I had grown in a small plot in about 40 minutes. I have also threshed wheat and oats with this machine. The design of the machine assumes grain is harvested with the heads only, which I currently do by hand. Total cost was less than $150 for the thresher itself and it took less than two days to build. I initially used an old 1/6 HP washing machine motor but it was not strong enough so purchased a Marathon Electric 1 HP "farm duty" motor from for $199. The motor wiring diagram turned out to be incorrect (110V and 220V wiring is swapped). I contacted Marathon Electric about this but they never returned my emails or calls. It runs fine using the 220V wiring with 110V (using the given 110V wiring produces lots of vibration, overheats the motor, and easily blows the 20A fuse under no load). After these photos were taken I ordered some real 1/2" bearings from for $9.95 each. These greatly improved its performance. The cost of belts and pulleys was somewhere around $40. These are sized to achieve a threshing velocity appropriate for the grain (about 700 RPM seems to work well). Threshing velocity tables can be found on the internet and in old farm manuals. Your cost will vary based on how much material you can scrounge. It would certainly be possible to power something like this from a tractor PTO or maybe even bicycle setup. Threshing time is around 30-40 seconds per batch and there is no screen. I simply thresh until that batch is done, knock down the grain and chaff, and repeat. If I ramp up my grain production, I will probably modify the unit to add a chute and a way to knock down the grain and chaff without stopping the motor. Winnowing was accomplished with a window fan, two water bath canners, and a large wash basin. It took four passes to completely clean the grain. The bread this made was delicious. There is a distinct difference between home-grown and store-bought grain. See also: more pictures and video of threshing and winnowing. IMPORTANT: I strongly recommend building a cover for belt and pulleys so clothing, hair, and body parts cannot get caught!

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