I am running a neighbors F2 in corn ( yes it is late I know He is 85 years old and broke his leg this fall and no other neighbors would step in and help ) I am running the cylinder at 600 with the concave wide open and 2 bars,and the fan set at 7 the cobs are clean but I am cracking a lot of corn and blowing a little corn over the seives, But I am still getting trash in the bin if I slow the fan down much it seems the trash problem gets worse