Pedal-Powered Food/Grain/Coffee Mill
Contents
Short Description
- Problem: Lack of electricity or lack of an electrical grinder.
- Idea: Combine a bicycle and a hand mill to a pedal-powered mill.
- Difficulty:
- Price Range:
- Material Needed: Bicycle, metal bars, wood, hand-operated mill, welding device
- How Many people?
- How Long does it take?
Concept
The machine is easy to operate, easy to maintain and reasonably portable. It can be used anywhere by virtually anyone. It is also a simple matter to switch from degraining to milling by unbolting one appliance and attaching the other.The Mill function has the capacity to mill 3 lbs. per minute of any type of grain or coffee beans. The most common use is for milling yellow maize, soya beans, and other elements that make up animal feed. The Corn Degrainer for example is used postharvest and easily degrains 1200 to 1500 lbs per day.
How to Build the Mill
The mill itself is hand operated and table mounted. Remove the central spindle. One end accepts the handle, the other end forms part of the grinding mechanism. The handle part is cut off completely. The mill will eventually bolt onto the frame. Re- move the table mount as shown, leaving a square, flat edge.
- Cottered axles are old fashioned but still widely available. They are more convenient for this task than a modern tapered type.
Our adapted axle needs a pipe shim. Insert one if required and trim any excess.
The corn thresher is adapted in a similar way.
Making The Chassis
The bike frame is cut as above. About 450mm of seat tube, 250mm of down tube and the full length of chain stays.
Here we have the interchangeable thresher and the degrainer, adapted to pedal power.
Form the 90 degree corners as shown, cutting, folding and welding the angle iron.
Top tube
Chain stays
Seat tube
Down tube
Seat stays
Weld the bike frame in place, lining up the sprockets so the chain will run straight. You will need to bend the drive-side chain stay in order to clear the chain.
To form a better bond, the frame is flattened and bent before welding to the chassis .
The completed chassis, with the bike frame in place. Construction drawings are provided on the final page.
File any sharp edges and paint.
Making The Flywheel
- ing the wheel. The welding option is easier but prone to causing undesirable wobble in the casette.
- per to prevent leakage.
- dundant unthreaded piece, and tap on a threaded one from an identical hub. Fit spokes using a screwdriver, rather than a spoke ten- sioner for speed.
Mix the cement with two parts sand. Place the wheels on a bucket to provide support.
Once filled and smoothed over, place in the shade to dry overnight.
The Seat
The seat is recycled plywood. The support is made from thin box section steel. See construc- tion drawings for more detail.
The concrete is painted to protect from moisture. One side accepts a multi speed cassette, the other a single speed sprocket. The axel position will need to be adjusted accordingly.
In order to make the seat position adjustable, there is a simple bracket. The nut is welded in place for easy tightening.
The seat can then be painted.
The Handlebars
We use steel dropped racer bars. Cut them in half.
These are then welded onto to cut ends of the handlebar and filed smooth. They are then ready to be bolted onto the chassis.
In order to bolt on the hangle bars, we weld 8mm bolts onto 20mm washers.
The Chain Assembles
The drive side derailleur is bolted in place as it would be on the bike. However it will need to be filed to fit flush with the frame. We use the old style of derailleur that bolts onto the axel rather than the bike frame.
Now you can add a gear shifter. A simple friction type is best than an index shifter. Use the adjust- ment screws on the derailleur to make sure it se- lects all gears without the chain coming off.
Now you can add the 2nd derailleur and the grinder.
Success Story
Guatemala
References and Further Reading
- Design & Realisation by Carlos Marroquin, Instructions by Henry Godfrey, Produced by Maya Pedal 2010, http://www.mayapedal.org/
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