The amount is determined by a choke on the intake and by the closeness of the cut-off points. You will have trouble with your shoe if these cut-off points are not the same distance
Q:I combine with a conventional MF8680 and follow the Combine Forum website for any comments from other 8680 owners. However, there is limited discussion on thresher settings or overall performance.
What sort of advice can you provide about operating the 8680?
– J. Howard Parkinson, Calgary
A:The best way to set this combine is to open the sieve so everything goes into the hopper and you can see what you are doing.
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Then set the cylinder speed and concave clearance and concave blanks.
For combines that return the unthreshed grain back to the cylinder, you might be surprised how much faster you can go. That raw grain takes horsepower to push through.
Your concave must have a positive edge from front to back, which means the clearance must shrink as you go back. You have gone too far if the combine starts slugging because the front is too much greater than the back.
The MF8680 has accelerator rolls that drive the chaff and grain mixture past a blast of air. The air is supposed to blow the chaff away but not the grain. This is a carefully controlled balance.
If the rolls are worn too much, you might notice that you have to turn the wind down because you are blowing it out the back.
If you are picking up a swath in a poor crop, you will also pick up a lot of dirt. This wears out those rolls pretty fast. You will quickly discover their value if you try combining canola with poor rolls.
Another thing that will happen as you reduce the air is that the air from the fan won’t be able to lift chaff off the shoe and you will carry grain out the back.
The air for all this comes from a drum-shaped fan with curved blades down its length. They draw from around the fan so that it will be filled with compressed air. We cut off the air from outside the fan if we want to take air from the fan.
The secret to setting the shoe for canola is that it needs a lot of air so that it can lift the chaff and grain mixture. Canola is carried out rather than blown, which means you have to keep the bottom sieve open at least one-quarter inch.
Many farmers use a shovel for counting losses, but this does not provide an accurate measure.
You might say to yourself that at least it will tell me whether I still have losses. Have you ever heard of a combine that had no losses? Neither have I.
You can either check on the ground or make your own calibrated shovel of a known size that can create a real reference on which to base your loss estimates.
I saw one mounted on the back axle and it was held in place by two sole-n oid latches. When the farmer pressed a button in the cab, this six foot by one foot tray fell to the ground and the combine put everything onto that tray.
The farmer said he had inaccurate readings from his sampling methods until he learned that the losses would vary so much from side to side.
For instance, returns on the old MF860 come out the left side and losses were higher on that side. We could have used this when we were moving the pinch point around on the 8570.
Understanding where the losses come from can help track down the processes that are putting them on the ground instead of in the tank. Think about how the machine works and what changes when you adjust the settings.
You might need a frame of reference to ensure you understand your individual machine’s performance. No machine will save everything. Put a value on your machine’s ability to keep it off the ground. For wheat, it is one bushel per acre when you are counting 22 kernels per sq. foot.
Let’s say you put a 30 foot header on your combine or swather and you are dropping your losses into a one by six foot tray that is a foot wide. You mul-tiply 22 by six and it gives you 132 kernels and multiply this by five to look after the concentration of a 30 foot header.
If you count all the kernels on the tray, you need about 660 kernels to give a one bushel loss.
The Prairie Agricultural Machinery Institute considers a three percent total loss acceptable.
Some losses happen at the header, depending on the crop, and some remain in the heads. It takes a lot of kernels to reach the point where you have an unacceptable loss.
Henry Guenter is a former service manager for Massey Ferguson. Contact:
