Fanning mills are used to clean the chaff and weed seeds from grain. Farmers cleaned the grain they would use for seed the following year (removing weed seeds) and they also cleaned grain they would eat.
Also called "winnowing machines" or "grain cleaners," they are still used today, mainly in the seed industries e.i. flower and garden seeds etc. My brother Carl Kannianen has a bigger version with basically the same idea.
These pictures are from my grandfather Arthur LaBrant's shop. Carl kindly explained to me how a fanning mill works. Cleaning seed grain was one of his jobs, so he has had way more experience running them than he would have liked--I imagine it would be a dusty and boring job.
Harvested grain is poured into the top hopper.
The machine is powered to shake the sieves (screens) and to turn the fan.
The early ones had a hand crank, and the later ones like Carl used, had an electric motor. Some models in the 1800s had a foot treadle.
The screens (slanted by the machine in picture below, left side) would be layered inside.
The biggest screen would be first, to screen out straw, and possibly rocks.
The grain (usually wheat, barley or oats) would fall through onto the screen below, small enough to catch the grain, and let the smaller weed seeds and debris particles fall through.
The wooden fan blades, shown below, blow the lightweight chaff and small weed seeds out.
Wild oats were the hardest weeds to separate from wheat, and they invented a specialty machine for winnowing out the wild oat seeds. The Emerson Kicker shown below was patented in 1907.
I thought the sound of the fanning mill working was exciting! Rattling, rubbing, gears turning, along with the motor noise. One of the many sounds in my nostalgic bank of farm memories.