Yes, I took a set of stock keystock grates to my local fab shop with a drawing of what needed done. I used the stock grates cause I ran out of time trying to draw up a set from scratch. So it cost a little more because of the shop time spent removing the keystocks, but they turned out great.
How do I like the helical concaves? I have no idea why any manufacturer makes any other concave. Helicals in an axial flow are the stuff IMO. Wont never be without them now that I have ran them. Thats why I built the helical grates to go along.
So far I've used them for tall fescue grass seed, wheat, and red clover. I have no intention of ever putting a stock keystock grate in again. The straw behind the machine was as long or longer than with the stock concaves and grates. The rasp bars make more difference to the straw length than the concaves or grates. If you want longer straw, you have to transport the material rearward faster and with less revolutions of the rotor.
We used to hire in a second machine to help us in grass seed. It was a 2388. A few years back I bought a full set of gorden bars and installed them with a set of gorden helical concaves with no wires. Here's a pic of the two windrows behind the machiens. The 2388 was stock with a specialty rotor and stock concaves with keystock grates. My machine had the gorden bars, no wire helical concaves and keystock grates. The left windorw in the picture is the 2388s and the right is mine. I was running about 450 rpm on the rotor and the 2388 was about 550.
I used a Lowen helical (in the first position) in beans this year. It has wires that are spaced like a small wire concave. I was getting an excellent sample, but I think losses could have been reduced little. I'm not an expert on beans, though. If we had more acres I'd definitely try something else. I also tried it in corn to see what happens, but it plugs pretty easily, especially in damp conditions. Corn kernels get stuck in the wires, too.
Don't the Gordon helicals have no wires? I bet they'd work pretty good in corn and beans.
To answer okieclayfarmer's question: I'm not sure. The manual says slotted grates for wheat, but sometimes I feel like they're not quite doing the job. We used to use Kuchar concaves and grates in our old machines, but the new one has factory equipment. We still have our Kuchar grates, but for some reason we have two different styles and one or two of each type is kind of beat up. I think right now we have one Kuchar in the first position and two slotteds in the rear. I guess I'll know how that setup works in June.
Yes, the Gorden helicals have no wires, and the bar spacing is a little closer together.
Sorry about the drifting off topic. In my area, the scrap guy gets pretty much all the slotted grates that came with the machines. Many were never ran. Keystocks seem to be the "do-all" grate for our cropping, wheat, grass, small seed legumes.
I see at least one manufacturer offers a grate blank. My personal opinion, which is just that, is that if you are overloading the cleaning system because you think the grates are too aggressive, I'd remove one grate at a time and install a grate blank. The sooner you can get the grain sperated, the better. By closing the grate spacings, you prolong the time it takes to get the grain out. When you do this, you run the risk of more straw and chaff coming through with it. So, again IMO, if you have the header or yield to push the machine harder, you may be able to run with keystocks all the way back.
I liked our Kuchar grates because they worked in all crops (except flowers). They're more open than a slotted grate and a little more aggressive, but not as aggressive as a keystock. Maybe this winter I'll try my hand at repairing our broken grates so we can put them back in. We haven't been able to get the 2388 to clean as good as our old machines, but we just replaced a bunch of stuff and with more experimenting with threshing/separating elements maybe we can get it worked out.
We've got two sets of slotted, keystock, solid, and Kuchar grates laying around. I'd like to get rid of them, but then I think if I ever get my own combine they would be nice to have.