I have combined lots of buckwheat. I usually start as follows: large wire, 1,2,3. Open 3-5. Rotor 450-500, fan 730-850. Chaffer 1_2-5_8. Sieve 3_8 - 1_2. You can thresh buckwheat as soon as the seeds are dry enough to give you 14-16% moisture. The chaff and stems will be green comming out the back. Good luck!