Modified roller modules

While Thom was working on the winnower, Jeff updated the roller modules to be more durable, as well as integrated a feed hopper.

We were having issues with the rubber staying glued to the rollers, so the design was modified to accept a rubber tube. We now have a seamless rubber roller that does not move or get caught up in the framework.




The belt drive wheel was moved to the opposite side for user safety, and all of the access points were moved to the front, so you don't have to dissemble the entire system to remove a roller.in the field



The feed hopper was integrated into the top of the module, which allows for the same design to be stacked on top of each other to create the 2 pass system. (The metal walls for the hopper are being bent today, so I added them in Photoshop...)

Winnower prototype

Sorry for the delay in posts...Travel, work schedule and the flu have kept me from updating...



Thom built a prototype of the integrated winnower, including a clear front so we could see how everything works. The ramps are adjustable to allow the angles to be tweaked.



Initial test went well, with a few seeds getting stuck on the ramp


A fair amount of chaff made it out of the system


While the seeds dropped down into the bottom



Our only concern is the ability to generate a constant amount of airflow using a hand powered fan attached to the hand crank. We plan to discuss with Erv during his visit this weekend.

Getting Closer...

A few updates from this weekends work...

Attached the natural rubber to the floating roller and passed the millet through 2 times. We are having some trouble getting the sheet rubber to stick to the roller and are going to special order some natural rubber that is formed in tubes, so we can stretch over the rollers and tack down. This should stop the rubber from lifting.

Even with the rubber sheet issues, wrapping the rollers has resulted in a significant reduction in broken grains.



Also mocked up a smaller feed area on the current hopper. This helped even the flow of millet into the rollers.



We are still dialing in the winnower, and need to find the right fan and speed to blow the chaff out of the system. On the left is the raw millet. On the right is the threshed millet after 2 passes and a few fans with a piece of cardboard.





Next steps, in order of importance

1. Wrap rollers with rubber tube
2. Re-build frame from Plywood rather than OSB
3. Integrate winnower
4. Incorporate gears and chain if possible

Final Concept...

Here is a quick sketch of our final layout. We have split this weeks efforts into 3 areas - Hopper, Winnower and Rollers

Thom will be working this week to integrate a winnower system based on CTI's recommendation. The idea is to make a small fan that blows air across the falling grain, forcing the chaff up and out the side.

Jeff will be working on the roller assemblies, adding rubber sheet to one of the rollers. This decreases the amount of grain breakage significantly

I will be building the hopper. I am using a plastic bin to start, and adding the ability to adjust the feed rate by varying the size of the opening.

The 3 of us worked from each of our homes today, so the images will follow shortly...

Test Drive...

Now that we had the roller modules built, we could assemble the 1st prototype and run a test.

In the meantime, Thom cranked out a quick "winnower", made with a variable speed motor from a used range hood. The winnower will eventually be integrated into the device and powered by hand, but this quick set up let us try different fan speeds to see what worked best to separate the lighter chaff from the heavier millet.

Here in Ohio, Thom seems like a pretty smart guy, despite what his sweatshirt says...

With the prototype up and running (quite noisily), and the winnower working, we dropped a few scoops of millet into the hopper and turned the crank. (sorry for the bad camera work...)

The object of the thresher is to extract the millet from its glume, while not crushing the grains. As you can see in the before (top) and after (bottom) pictures below, we did pretty well for the first test!


By this time, sunlight was fading fast, and we were fresh out of doughnuts...both good reasons to call it a day (along with the hallucinations caused by fumes from the kerosene heater). The last image below is a side by side comparison between the original Leary thresher, and the refined prototype. We have reduced the size and weight considerably, and will be able to send this over to Mali in a suitcase rather than a crate. This will save time, money and running the risk of it getting lost in shipment.



Next Steps:
- integrate winnower
- wrap floating roller with rubber to reduce grain breakage
- incorporate sprockets and chain
- build stable base

Modular is king...

After a quick brainstorming session, Thom, Jeff and I decided that the first task was to design and build a modular roller system. The original Leary prototype is based in an antique wash roller that was modified to remove the outer "husk" from the millet.




We wanted to create a simple but robust roller module that could be built from sheet stock and the same design could be used for both top and bottom (hence the "2 pass" name) rollers.

Jeff, in his mechanically "savant" way, built the first set of working prototypes in a single day, and they worked perfectly. Building off this great start, we built a second complete set out of durable material and gave it a spin...

Once we got the first set spinning, we assembled the second set, mounted it to a temporary frame and added some pulleys and belts to spin both. We plan to use sprockets and chain for the final device, but this was a way to get us up and running quickly.

The Leary has landed...

The "Leary 2 Pass Thresher" was shipped to my house so we could start the project to refine the next generation device before shipping it off to Mali for field testing. It received good marks from the USDA testing facility, but was in need of refinements.

After the first meeting, we moved the operation to Jeff Held's garage. It was still cold, but at least he had a real workshop...