Are the concaves small wire or large? It really doesn’t work on Deeres to run large wire in Canola, the shoe gets overloaded with to much material and it cant separate and sample gets dirty. Also how good of shape is bottom shoe in and how open is last 12inchs of top shoe.
Dirty canola samples can be a problem with the Deere S600 series. Doesn’t seem to matter what concave.
I assume the straw is dry and the sample is dirty from overthreshing. If straw is tough ignore the following advice.
If you have a variable stream rotor advance the discharge vanes.
Do a kill stall. Look at how evenly loaded the chaffer is. This is the most important step in an sts combine. If chaffer has deep spots and thin spots you will get a mess in the tank.
5 ways at least to modify how even the chaffer loads.
1. Feed the combine evenly. If the crop comes in gob after gob you will have ugly sample.
2. Rotor speed will influence how even load is on chaffer, mainly front to back loading.
3. Concave clearance will also influence left to right loading on the chaffer.
4. Deere uses adjustable cover plates on their concaves. In some crops it helps to cover the sides of the concave and leave the Center open to help with even chaffer loading. Howard concaves have cover plates and could possibly help.
5. Covers on sts separator grates. Putting the covers on helps reduce loading the outside of the chaffer.
6. Rotor vane adjustment helps get the material out of the rotor faster and reduce the chaffer load.
Everyone’s conditions are different so hard to give universal advice. Often morning and evening settings are different than afternoon settings. I suggest 2 kill stalls one in morning and 1 in evening. A bit of work, but a real eye opener on how the adjustments effect the combine performance.
If dry straw is causing your dirty sample I would start with rotor vanes advanced, 2 rows of filler strips on left side of separator grates and 1 row on the right, 600 rotor, concave 20, fan 850, chaffer 14, sieve 6. Adjust from there.
Owned a S680 for a few years and test drove a S790 automation last year and nothing much has changed, hard to get a clean sample. I don’t mind a bit of chaff in my sample as long as I’m not throwing over. I’m much happier with the samples on my red and yellow combines, last year our average dockage on canola averaged 1%.