F2 over-threshing the corn a bit

Looking for any suggestions on lessening the over-threshing I am seeing in my corn currently.

The F2 is sending several whole cobs out the back, a couple here and there with a half-dozen kernels or so still on the cob. Some cobs come out broken but none are split the long way. Have the 20" cylinder sheave turned all the way down to 412rpm. Three channel bars on the concave doors currently, 1-3-5. Cylinder clearance set to a bit over 5/8". No lap bars on cylinder. Given all of this, still seeing about 5-6% FM due to damaged kernels.

Considering removing, or moving, channel concave bars... or swapping out one or two of the channel bars with angle bars I have.

Moisture is usually running around 15-17%.

settings appear to be very close to what I would have ran on the f3, I would maybe run a little slower on the cylinder speed but in the ball park. I would set my clearance at 3/4. is your cylinder calibrated on the clearance scale. Not sure that the kernals on the cobs are a major issue unless the majority have this, fm/damaged corn was always a concern with cylinder speed/clearance in dry corn. I could run slower so I guess I had a different sheave.

Changing from channel bars to angle bars will reduce the contact area between the cyl and bars by one-half. Do that. Do not remove the front door bar, unless you change it to an angle bar. YOU NEED THE FRONT DOOR BAR FOR ROCK PROTECTION!

You are setting it wrong. You need whole cobs out the back. ( 5/8 is too narrow) Then increase cylinder speed until all the kernels are off the cob.

You are running your cylinder slow but are grinding it because you have the cylinder set too tight.

Open the cylinder up some and drive faster. YES faster. Corn on corn will not damage the kernels like steel on steel.

So 1) Open the cylinder up until you have 90% whole cobs out the back.

2) Speed up the cylinder until you have few kernels left on the cob. Keep the combine full while you are doing this.

In dry corn the walkers, chaffer, and sieves will handle a lot of corn. So keep the cylinder full and you will get a better thrashing with less damage.

I can't get 90% whole cobs out the back because I have a chopper running. Already at 90% whole cobs, or better, coming off of the chaffer. Will try opening it up more before I start swapping concave bars but I'm already running low-mid 2nd gear here with plenty of corn going in at 190bpa. Most of the corn is coming in at 15%.

JM42: The cylinder speed is set as slow as it can be set with the belt drive.

If you are running a chopper then just check on the top of the straw walkers. The out the back means off the cylinder. Do you have the low speed corn drives on this machine??? There are three different drive pulley/belt combinations used on a Gleaner "F" combine.

1) High speed (small pulley) and shorter belt. Allows up to 1000-1200 cylinder RPM

2) Mid range ( medium size pulley) Called the universal pulley because Gleaner brought it out when guys complained about have to change pulley for corn and soybean to oats and wheat. IF this is the one you have then it will not go slow enough in some corn. It only goes like 450-800 rpm. Really does not work the best on corn or wheat.

3) Corn drive pulley (Larger pulley and long belt) Drives cylinder 250 -600 RPM.

Also you should be able to open the cylinder up and THEN drive fast. If you are crowding it with the cylinder set too narrow that you will just make it grind the corn worse. Open it up until you start to see some whole rows of kernels on the cobs. Then really speed up and see if the rows of kernels disappear. If not narrow it up some and keep going fast.

Also have you checked to see if the cylinder bars are worn?? Worn out cylinder bars will make it shell funny. Also check the cross level on the concave. I have seen them off side to side and that will make them grind it on the one side and let kernels through the other.

You do have cylinder bar filler plates in?? Just checking. I had a guy on here a few years ago having all kinds of trouble and he did not have them in. Makes it impossible to run a good corn sample. I am sure you do but just wanted to ask.

Keep playing with the setting. Usually a Gleaner can be made to have a real nice grain sample. It just take some adjusting and switching of things.

Yes, the cobs on the walkers are almost all whole and the cob screens are working great.

According to the OM I have, F2 SN<46000, my current belt+pulley combination is as slow as it gets. The pulley is the largest one they made for the F2 at 20in, which has a speed range between approx. 410-680rpm. They had a chain drive option for the cylinder, which could go down to 175rpm, but the combine didn't come with that and I think that is too slow anyway.

The cylinder bars are good, I turned them earlier this year before doing small grains......and no, I do *not* have the cylinder lap bars, or "filler plates", the guy I bought the combine from didn't have them. The OM suggests adding the filler plates when you cannot get complete shelling, while trying to run whole cobs, within the suggested RPM range, 400-700 and cylinder clearance of 3/4in.

Went back to 3/4in this morning per your suggestion, also tried 7/8in, with a variety of ground speeds in 2nd gear. Still about the same for damage regardless, 5.5-6.5%.

Yes the 20" pulley is the one for corn. As I remember I tried corn once without the filler bars, and thereafter always put them in.
Dad used to put "half-round" concaves in his E to do less grinding.
I'm surprised you can go as fast a you are in corn that heavy. The limiting factor for my F2 was the clean grain elevator. Once we started exceeding 140 bu. corn I was running in first gear. But then here in the cold wet northeast, corn usually isn't that dry.
I put a full complement of rasp bar concaves in my F2 and left them in year around. I don't know what that would do for you. Maybe you need rubber concaves!

Hi Bob, to be honest, I'm a little surprised myself that I can move the variable forward in 2nd as much as I have and still not hear the clean grain clutch slipping, but it hasn't yet. I have been waiting for it as I move that lever forward!

What problem did you solve with the filler bars? Was it over-threshing or incomplete shelling?

Funny you should mention the rubber concaves! I was just thinking about that this morning. As mentioned previously, I have a set of angle concave bars, which I think may be what is considered "half rounds". I was going to try replacing the channel concaves with those as a next step and see what happens.

guys is it possible that the bars could be contributing to some of this sence he recently turned them. I have never turned the bars before but I did experience some of this with new bars until they polished out a little.

I can't remember, but I think it was both. Seems like to get complete shelling without too much grinding, I put the filler bars back in, Just like JDSeller says.
I only took them out because you're supposed to when you speed up the cyl. for small grain. Although I had a neighbor with an early F who just left his filler bars in year around.
Half rounds are literally just that- half round. Threaded to take a 3/8" capscrew. I think you're talking about half- channels? Just a standard concave with one edge cut off.

Yes, the other concave bars I have are half channels.

The filler plates make the corn only go through the cylinder once. They can not come back around by falling into the center of the cylinder. I would try to get set of filler plates. Most guys around here left them in all of the time. It may cut back on your capacity in wheat/oats but usually you are not at full capacity in those crops anyway.

You can try the half rounds in the door. The half channels may help but they still have sharp edges and may still damage the corn.

Also do you have the cornhead book for your machine??? Reason I am asking is that some of this is covered in it not the combine book. Gleaner was kind of unusual in that the header books also contained much of the information needed on the combine for using the header.