I run my rotor speed at 250 rpm. Set concave to slightly less than your cobb diameter. I cut off every other rotor discharge paddle and now have even wear on the chopper knives. A corn chaffer will give you better cleaning with more capacity.What is best cylinder speed and concave setting for north dakota corn, seems to brake corn up to much, anybody see on high speed chopper blades wear to much on inside, just like older combines did,how much better will it work with corn chaffer??