Beans unwrapping machine

During a visit to Maroua in northern Cameroon, I watched farmers unwrap beans entirely by hand — slow, punishing work that throttled their output. Machinery to do it was either unavailable locally or unaffordable for small and medium producers. Any real solution had to suit rural Central Africa: limited materials, no specialist maintenance, portability across dispersed communities — while still hitting 85%+ yield, cutting operator effort and meeting health-and-safety requirements on a tight budget.

I built competing prototype configurations before committing, choosing the final design on material availability and manufacturability. Variable-dimension blades at 120° intervals with 5 cm spacing were tuned — rotation speed against motor torque — to unwrap beans without breaking them, with a double-groove pulley partitioning drive between motor, shaft and fan. When the specified 1.1 kW motor proved unavailable, I adapted the design to an alternative while holding every performance target, and balanced steel thickness against machine weight for portability.

A machine that meets its performance targets and can genuinely be built and maintained where it's needed. Working with Nepitimbaye, Grace and Tatsinda drove home that engineering in constrained environments has to absorb real-world unpredictability — and that setting teammates up through patient onboarding beats shouldering every task alone.