Women in Tanzania have to walk long hours to distant milling facilities. The machines in these facilities cause a loss of maize during grinding, are expensive to use, and often have unreliable access to electricity.
The Goal
Improve daily food processing in rural Tanzanian communities by introducing a hand-powered corn grinder that is portable, electricity-free, and made entirely from locally available materials.
Context
In many rural Tanzanian communities, women grind maize to make their country’s national dish, Ugali, a staple corn pudding. This is a time-consuming, labour-intensive task primarily done by women. On average, women in Tanzania spend four timesmore hours on unpaid domestic work than men. Maasai women often walk long distances to village-based milling facilities, which are costly, unreliable due to frequent power outages, and lead to 2kg of maize loss per grind.
50%
of daily calories in Tanzanian households come from Ugali.
65%
of Tanzania’s population lives in rural areas with limited access to grinding facilities.
62%
of Tanzania has no electric grid or no connection to an electric grid.
92%
of the rural areas of Tanzania do not have a reliable electricity supply.
Opportunity
Improve daily food processing in rural Tanzanian communities by introducing a corn grinder that is portable, electricity-free, and made entirely from local materials. Reducing travel time to distant milling facilities and minimizing maize waste can empower women, enhance food security, and create opportunities for small-scale corn-grinding businesses.
Affordability
Using inexpensive and widely available materials and local manufacturing.
Variability
Using size adjustable mechanisms to fit all users and removeable components for cleaning and portability.
Durability
Using weather-resistant materials and replaceable parts to ensure durability and ease of maintenance over time.
Currently
In Tanzania, electric corn grinding facilities are often only available in the larger towns. These facilities typically feature two electric corn grinders designed to process maize quickly.
Mechanism Exploration
Typical hand-crank grinders are made using expensive manufacturing methods that cannot be recreated in rural Tanzania.
Flat burrs
Course grind, adjustable plate distance, hard to grind, weak table grip, bits of metal chipped into the grinds, and unable to be produced in Tanzania.
Conical burrs
Finer grind, hard to grind, adjustable plate distance, and unable to be produced in Tanzania.
Conical and flat burrs
Course grind, easy to grind, adjustable grind plate distance, does not require advanced manufacturing methods, and is possible to recreate in Tanzania.
On-site Research
Through calls with Tanzanian locals, I explored ways my machine could best work for them. By talking directly with Maasai women, I was able to understand their daily routines, preferences, and priorities when it comes to maize processing.
My Findings
– Women would store the grinder in a dedicated corn grinding boma.
– They want to use it while standing, with the handle turning clockwise.
– Corn would be ground directly into a bag or bucket.
– They typically grind enough for one family meal at a time.
– The grinder would be used exclusively by women.
– The flour must be very fine to be suitable for Ugali.
– They hope to use the grinder to create a small grinding business.
– While not moved often, they would want it to be portable.
– The grinder should be easy to take apart for cleaning and maintenance.
Prototyping in Tanzania
I worked with local welders and translators to bring my prototype to life.
I used anthropometric data to determine key design dimensions, ensuring the grinder fits comfortably within the range of a 50th percentile woman. Measurements such as elbow height, arm reach, and grip diameter guided the positioning of the crank, the overall height of the grinder, and the handle size, making the device ergonomic and efficient.
Weight considerations:
– Safe lifting capacity: 10–15 kg
– Design Implication: Break into parts under 8 kg, each no longer than 90 cm for ease of carrying and setup.
Presenting in Tanzania
I presented the prototype I had developed in Tanzania to a group of 30 Maasai community members and local manufacturing business owners. The response was highly encouraging, proving clear interest and confirmation that the product filled a real need in the region.
The primary concern raised was that the grinder must produce a fine flour, as the current version only produced a coarser grind, which was not suitable for preparing Ugali.
Concept Actualization
Since the corn needed to be ground finer than I had originally thought, the grind plates had to have a tighter tolerance. This meant I needed a rotating auger to push corn through the plates. I designed a new type of grind plate that could work with an auger, while also being easy to produce locally.
Classic grind plate
Cora grind plate
– Made using expensive iron casting or metal CNC cutting.
– Time consuming to angle grind and requires a plasma cutter that can etch to recreate something similar.
– The plates are usually concave to allow the coarse original item to funnel into the center. This curve is extremely challenging to recreate using local manufacturing methods.
– Can be made using an angle grinder as it allows for large tolerances.
– Can be made using plasma cutting, an inexpensive method that can easily be mass produced, and does not require an etching tool.
– Large ridge in the center allows unground corn to funnel into the middle, and the star ends guide the corn towards the edges.
– Achieves the same result with fewer cuts.
The corn hopper holds enough corn to feed up to five people. This is an ideal size for a Maasai family in Tanzania, which typically consists of five to eight people.
Most corn grinders use a cast iron auger, which isn’t practical to produce with simple tools or local materials. Instead, I used standard steel washers or split lock washers, which are widely available and easy to work with. The threaded rod allowed the grinding plates and handle to be screwed on securely, creating a functional, low-tech auger that could be easily fabricated with basic tools.
The bent metal tube handle provides a natural turning motion for the user. The final handle length balances torque and ease of rotation, while remaining simple to produce and repair locally. The grip features a wider diameter and an extended length for a two handed grip, specifically tailored to fit the hand breadth of a 50th percentile woman.
I designed bean-shaped feet. This shape provides a platform that the user can step on to add downward force if the machine is on uneven ground. Additionally, Users can place rocks on the feet for extra weight or insert a wooden peg through the hole to secure the grinder in place, ensuring it remains steady.
The Final Outcome
This resulted in a hand-powered corn grinder that can grind corn into a fine powder, come apart into pieces, and adjust in height.
