Since in a few months, it will be time to harvest grain again, I thought it would be a good time to show my bucket thresher, so you can see how it works. I'm not very good at keeping the names of things straight, so forgive me if I use descriptions instead of technical terms.
To build a bucket thresher, you'll need:
-A 5-gallon bucket with lid
-A power drill. Faster is better, but it doesn't need much power. Kind of the opposite of what a good drill should be.
-A threaded rod. Slightly longer than the bucket is tall, and that will fit into the drill.
-2 lengths of chain, slightly shorter than the inner diameter of the bucket.
-4 washers that will fit between the links of the chain without the chain slipping over them.
-1 bigger washer, with a large interior hole. This is to keep the thresher from tearing up the lid of the bucket.
-4 nuts, that will fit on the threaded rod.
-Loctite glue
Thread the hardware onto the rod as shown:
(Ignore the laundry basket. I forgot it was there.)
You can play with the placement of the chains until you find a spacing you like. When you decide on a spacing, use the loctite to glue the nuts in place. If you don't, the chains will spin themselves up and down on their own while you're threshing, and that doesn't work so well.
Cut a small hole in the center of the bucket's lid, and tape the big washer over it.
After the loctite has set, you're ready to thresh! I've found short pieces thresh out better than long ones. Just fill the bucket loosely, about 1/3rd full:
Thread the rod through the lid, and attach the lid securely. Hook the end of the rod up to the drill:
And spin! I found it works best if I hold the bucket between my feet while threshing, otherwise it tends to buck a lot.
With the drill I used, it only takes about 10 seconds to thresh out the lambsquarters and amaranth I picked. I use a spaghetti strainer to sift out the stems from the grain:
The grain still has hulls and chaff in it that will need to be winnowed out:
Winnowing is best done with an electric fan. That gives you better control over how strong a breeze you use. With small grains that becomes especially important, it doesn't take much for the grain to blow away!
I didn't get a chance to winnow this batch yet, so I'm afraid I don't have pictures of the finished product. But that's the threshing part.