Add some legs to the bucket. Make sure the motor is at least 6 inches or so off the ground; the short legs on mine make the motor sit in the seeds and...
This bucket thresher is a small version of my bigger seed threshers for breaking the seeds out of dry seed heads of wildflowers. Using an old blender motor, and five or three gallon bucket with lid, plus a few other materials, this can be put together pretty quickly.
Use a small plastic flower pot (this becomes a dust cover for the motor) as a guide for making a circle on the bottom of the bucket in the center. Then mark for three holes around the circle (see the picture.) Cut out the three holes; tin snips work well for this.
Step 2: Add screen
Cut the quarter inch hardware cloth to the shape of the bucket and cut the center some to make room for the motor. Use zip ties (use more than shown in picture) to attach the screen to the bucket.
Step 3: Add motor
Take apart an old thrift store blender and keep all the bolts, switches, etc. Drill mounting holes into the bucket and flower pot. Cover the motor with the flower pot and attach the whole thing to the bucket. Wire up a power cord to the motor; add a switch, but it's not needed when the variable speed motor controller is used. Tape up all wire connections with electrical tape to keep the dust out.
Step 4: Threshing head
Attach a plastic soda bottle cap to the motor shaft by drilling a hole in the center and bolting it to the shaft. Drill two holes in the side for some string trimmer line. Using the bucket radius as a guide, cut and add some line into the cap. Simple knots and centrifugal force keep the line in the cap. Note: This head can be improved somehow, the plastic cap just isn't tough enough for some harder seedheads like echinacea. I'm still brewing on what to use.