Scale-Model Case Threshing Machine

Al Jeske built a scale-model Case threshing machine and the best part is, it works!

Al Jeske

Al Jeske with his thresher when it was about 90 percent complete.

Photo courtesy Al Jeske

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I’m a city kid, born and raised in Milwaukee, Wisconsin. In the last years of grade school in the early 1940s, I worked on a farm during the summers. The farmer worked only with horses, but the local threshing crew came around and harvested his oats.

In the last 15 years or so, I have been involved with the England Prairie Pioneer Club south of Verndale, Minnesota. We have the usual farm show features: sawmill, threshing, shingle mill, museum and exhibits. Following a challenge of sorts, six years ago I started to build a 1/16-scale Case threshing machine. My plan was to make a machine that would actually thresh grain, and my choice was that it would be millet. Therefore the cylinder and concave would have to thresh, the beater would have to beat, the straw shaker would have to shake, the sieve would have to sift, the shoe would have to shake, the auger would have to auger, the elevator would have to lift the millet seed and the blower would have to blow the millet straw onto the stack.

The only plan from which I worked is the “centerfold” cutaway view from an original Case catalog. I was able to scale the drawing at approximately 1-1/4 times in order to make 1/16-scale drawings as needed. I also had access to a Case thresher at England Prairie for pictures and measurements.

The basic machine is made of 0.012-inch sheet steel. The framing is brass angle and channel. The majority of assembly is by means of brass nuts and bolts, ranging in size from 00-90 to 3-48. The chain in the elevator and feeder is ladder chain. The teeth on the cylinder and concave are spaced to thresh the millet kernels. The straw shaker is of wood construction. The sieve is perforated 0.031-inch steel, the holes being just the right size to clear the millet kernels.

As the kernels are shaken back, they fall into the shoe, which shakes the kernels down over a 0.025-inch wire mesh and into the auger. As the kernels pass over the mesh, the chaff blower blows the chaff back toward the straw blower. The auger has to move the kernels across the machine from left to right and into the elevator. Because of the rotational direction of the elevator (counter-clockwise), it was necessary that the auger be a left-hand thread.

Here I wish to make mention of Sherline Co., Vista, California. My lathe and milling machine were made by Sherline; the people of that company were very helpful in getting me the extra gearing needed to make my lathe cut a left-hand thread.

One of the more challenging items was developing the proper curvature for the straw blower enclosure. It was helpful that I had previous experience in making sheet metal ducting. There are hinged inspection doors over the blower, the cylinder and the knife mechanism. (The knives, by the way, are made from razor blades.)

The blower pipe is made of telescoping brass pipe. I had it nickel-plated to give it a galvanized appearance. By means of the small crank handle, the pipe extends and contracts. Another challenge was cutting a ring gear to match a worm gear I had on hand that was needed to rotate the blower pipe 360 degrees.

The thresher made its debut before it was really finished. I needed to finish the elevator, weigher, grain chute and still needed belting but the 2013 England Prairie show was underway, so I displayed the threshing machine when it was 90 percent complete.

Some 1,200 hours later my project was finished and shown at the 2014 England Prairie show. This has been a great learning experience. Like Thomas Edison, I found out that there are a lot of things that don’t work. FC

For more information:

- Al Jeske, a retired electrical engineer and newly retired pastor, is a longtime model railroad enthusiast. In the past 14 years he’s become interested in metalworking with a lathe, milling machine and drill press. Since then he’s built several small steam engines, a Stirling engine, and a 1/16-scale working sawmill.

- Contact him at 28497 Owl Dr., Browerville, MN 56438; phone: (320) 594-3034; email: revajeske@twecwb.com.