Combines cob breakup problem

Wouldn't touch the sieves until you address the source of the cob breaking. Try 1.1 - 1.2 on the concave with a rotor speed of 200-250 rpm. The knives on the rotor can cause cob breaking also; you may have to remove some of them if you have particularly fragile cobs. Third thing to try would be to run your drum stops on feeder chains in grain position if they are currently set to corn; can help to keep cobs lying flat until they reach the rotor to ensure they enter the rotor at the proper orientation.

Do you have the rotor set as it came from the factoryIJ If so they rec. an initial setting of 400 on the rotor and concave clearance from .4 to .7. Raise sep. grate from 9 to 8.

there are lots of good ideas here, IF I were in the field, one adjustment at a time, I would n1- check concave level and adjustment - with front dropped to between 1_2 and 9_16" and rear setting at the size of the average cob you are harvesting try it, then n2 move the sep grate up to as much as 1 number closer n3 increase cylinder RPM until crackage occurs then slow back down to acceptable sample to obtain max capacity (lower cyl speeds break up cob more),n4 lOWER the top chaffer down to 1_2" or even 7_16" - I don't think you will have any shoe loss. Then as a last resort remove the knives. The thing we noticed MOST about the CDF was the lower break up op cobs - keep in mind conditions and varieties can make tremendous changes to normal settings. - let us know if anything helps or what helps _helped.

Thanks fellows for the ideas, I went with cyl speed 220 under load, opened the concaves to 1.0, chaffer closed up one notch. This seemed to take a good bit of cob bits out of the sample. I'm still playing with the idea of closing the seperator grate one notch at a time, that's next. Slower cylinder speed on the CDF seems not to crack the grain as much either......I'll keep you posted, back to the field I go, thanks again you guys.

Speed up your rotor. probably need it at 350-400 RPM.

So, may I ask what you think of the CDF so farIJ Are you satisfied with the rotor lossIJ Power consumptionIJ Also, do you have a Sisu engineIJ If so, what do you think of it.

We shoulda had the cdf years ago! Not much power to run it and does an excellent job in green stem soybeans. We are running the cummins engines. The cob problem was due to drought corn with mixed ear size which I will have to just live with a certain amount of cob bits and rotor loss while (trying to shell it all) We got into some irrigated corn today and it's doing an excellent job, almost no rotor loss and clean sample.

Thanks for the reply! Glad to hear it is working for you. It won't be long and we will be putting a CDF into one of our combines so I appreciate the above info and any other insight you may have on how to configure it.