Grain bikes: Human-powered seed processing tools for small farms

Once the initial prototypes proved the idea, there remained several objectives:

*Improve the performance of the machines

*Lower the cost of materials by ~30%

*make step-by-step plans to guide people building the machines

*make accompanying video to promote and support their construction

Here is an in-depth look at each objective:

IMPROVE THE PERFORMANCE OF THE MACHINES:

The thresher generally makes between ½ #/min (rice, wheat, some beans) to 1 #/min (rye, wheat, most beans), or even a little more with certain beans.

The fanning mill easily exceeds 1#/min for all crops we tested. 5 or 10#/min is normal for most beans. Some crops, however, will require multiple passes. For example, rice usually takes one pass before dehulling and then a second pass after dehulling. In a test of rye, processing just 10 lbs took less than 10 minutes even including set-up time. The fanning mill was designed to be highly adaptable to different possible uses. We did not have the opportunity to use it for all its possible uses. For example, grading seed (separating large seeds from small ones, or one type of seed from another) and cleaning small light seed (such as amaranth) remain unproven. The big expense and difficulty of the fanning mill is obtaining the exact right size screens for each crop. Screen selection is tricky. The presence of something seemingly insignificant, such as the awn on a rice grain, can make a screen not work properly. I hope that if farms build and use the fanning mill for certain crops, they are willing to share on Farmhack what screens work and don't work for various crops.

The dehuller now handles rice at only .5#/min. And depending on the variation in grain size, often requires two passes to get the rice dehulled completely. However, in just a couple of iterations I was able to increase the throughput several times, so I'm confident that greater productivity can be achieved with no increase in cost.

The seed fractionator is not my design. During the course of the project the design was made available by a seed company in England. I built a prototype (powered by an electric vacuum) and it works fine. It is really specifically for grading seed for germination tests, so only applies to farms which intend to sell seed .

The bicycle PTO is a useful way of using bicycle and excercycle parts to make a power unit that can be used for all the grain bikes as well as other bicycle powered machines. I explored two possible designs. One uses only bicycle parts, the other uses angle iron from an old bed frame. Both use the upright (rather than recumbant) rider position, both use a flywheel, both use gears, and in both designs the rider faces the work. Excellent as they are, the extra materials and time may not be worth it compared to just using a scavenged excercycle with few alterations. One exception is for farms which want to use a bike powered flour mill at the farmer's market to let customers grind their own fresh flour. In this case the extra power demands of making flour and the variety of levels of ability of customers requires a bicycle PTO with gears and a good flywheel.

*LOWER THE COST OF MATERIALS BY ~30%:

The price of the materials to build each machine, excluding scavenged bike parts, is now well under $200. In one build of a thresher I spent $148.75. In a build of a fanning mill I spent $145. While some of the materials were scavenged, much the lumber was bought at a premium from a local mill. The cost of the metal parts for the dehuller come to around $125 for one unit and less if multiple units are made at once. The seed fractionator is so cheap to build (excluding the vacuum to power it) that I didn't bother to account for the ~$5 in materials used. It's easy to imagine a determined farmer scavenging all the lumber and some of the metal to make these machines, lowering the price of materials even farther.

That being said, the labor cost of making these machines on a one-off basis are considerable. In one thresher build I spent 21 hours of labor, and building a fanning mill took me 39 hours. Building a mill is somewhere around 30 hours of labor, and the seed fractionator comes in at about 6 hours of labor. The step-by-step plans make it possible for the labor to be divided into smaller parts so that the machines can be built with “spare time” at night or on consecutive weekends.

In addition to the labor, the machines need to be stored under a roof in a dry location protected from rodents, which adds expense. However, because the machines (like so much farm capital) only get used once or twice a year, they can be stored in a compact form and set up for operation when needed.

*MAKE STEP-BY-STEP PLANS TO GUIDE PEOPLE BUILDING THE MACHINES:

The plans Emily Vogler created for the grain bikes are fantastic. I have often lamented how lifeless blueprints are. Blueprints make it possible for the trained engineer to build or imagine an object with no possibility for error or interpretation. That's often good. However, the grain bikes are “design platforms” in the sense that as each farm's needs are unique and resources are different, each builder will modify and adapt the design to suit their situation. For example, a farm planning to dehull a ton of rice per year will modify the dehuller to use a steel bed plate (for durability) and an electric motor for power. Emily's plans, instead of being blueprints or cad files for a 3-d printer, are human oriented. They are sequential, step-by-step instructions with an easy to follow progression across the page. When I used the plans to build a fanning mill I filled the pages with my own notes, added dimensions as needed, modified the plans with a red pencil to account for small changes I made, and kept track of my labor and expenses for each step right on the page for that step. What a pleasure compared to reading a blueprint! In addition to breaking down the construction into a sequence of steps, each step is organized by construction type (bicycle work, metal work, wood work), so a prospective builder can organize their build plan accordingly.

Unlike some DIY plans, these plans do not include a cut list or materials list. This is because each builders lists will surely differ depending on their needs and resources. By going through the whole plan and making their own materials and cut lists, the builder can fully understand the build process before starting. I feel this is better than mindlessly following a “recipe”.

MAKE ACCOMPANYING VIDEO TO PROMOTE AND SUPPORT THEIR CONSTRUCTION:

The original plan was to make one video showing how the machines worked, and one video showing how they are built. It became clear that the second video would be too long, so we decided to make one video showing how the machines worked and promoting them, and one video construction tour of each machine. The fanning mill, for example, requires a long video tour, while the seed fractionator, doesn't need one.

The videos accomplish several things. First, few people read detailed plans unless they are seriously considering building something. So the videos play a promotional role, allowing word to spread that the plans are available without burdening people with hours of study. One benefit of the promotional role of the videos is that they can be used to gauge interest in the designs. For example, as of this writing 723 views of the introductory video have occurred, while only 139 views of the dehuller construction tour have occurred. From this a tentative conclusion can be drawn that 80% of the interest so far does not go beyond amusement. That 20% appears to go beyond amusement is highly encouraging. In addition to the promotional role, the videos go further than the plans in bringing the machines to life. Instead of “five pounds of product per minute”, a farmer sees clean black beans pouring out of a chute and says, “Hey! Those are black turtle beans, I grow those, they are delicious, and I hate sorting them by hand!” Also, while the 2-D plans can be intimidating to the prospective builder because in the computer all cuts are perfectly square and all welds are seamless, in the videos a builder can plainly see that these machines can be built by amateurs with inadequate tools. Sheet metal was not bent on a brake, but rather with a pair of pliers, and most parts are not made more accurately than the width of a sharpie line. Chains do not align with sprockets, and belts are irregular and slack. This should encourage amateur builders.

One problem with the video arose from our ideological commitment to cinema verite. All of the footage was shot documentary style at actual events where we were building or using the machines. This effort to present “real life” to the viewer is laudable, but made the editing take too long. In the future we would choose to script each video and shoot it scene by scene.