Technical Development in Cambridge (2019)

The design and testing changes in Cambridge before our trip to Kenya in Summer 2019.

The technical development process within Cambridge involved iterating and developing the two machines (a shredder and kiln) that we would implement in the field later in the year. We employed research-focused design, calling on the expertise of academic staff to advise us about the feasibility and effectiveness of our design decisions. The prototyping and testing stage were also largely completed in Cambridge, utilising the student Makerspace, the Dyson Centre, and the staff on hand to iterate through various developments of our ideas.

Initially, the shredder sub-team (Tse and Aleyna) conducted research into existing shredder designs. The ‘Precious Plastic’ website was very useful, yielding a community of shredder fabricators, tried and tested in a range of different contexts. This gave the team confidence that utilizing open source-designs would provide a sound technical solution, allowing them to shift their focus to making suitable design changes to make the technology appropriate for use in Takaungu. This was achieved by thoroughly engaging with the design process, sketching, making cardboard prototypes and carrying preliminary tests. To avoid reliance on a potentially unreliable electrical grid in the village, the team opted for a human source of power by pedalling on a bicycle. The team decided to place the shredder slightly in front and to the side of the operator as the most ergonomic configuration. The bicycle pedalling system was reconfigured, with the support of technicians in the Dyson Centre. The preparation of all the necessary items to take to Kenya was another challenge. The team had to repeatedly return to Cambridge over the summer to plasma cut over 75 pieces, as well as fabricate the parts of the bicycle and shredder stand, purposely designed to be flat pack for easy transportation to Takaungu.

Similarly, the kiln sub-team (Egle, Shiv and Zinzan) worked to develop a more thermally efficient combustion chamber. The team overcame problem fixation, initially conducting in-depth research about the ways in which the efficiency of the existing kiln design could be developed. Based on analysis of potential solutions, the team met to ideate, develop and then evaluate design ideas against a specification. The team also used the powerful tool of rapid prototyping with cardboard. Rather than initially trying to design a “perfect” CAD model to then manufacture, this technique allowed the team to quickly identify potential fabrication issues that might arise in the field. This was extremely important to ensure that the designs could be manufactured with the resources and techniques that the local technicians would have had available to them in Kilifi. This involved continually trying to identify failure points and simplify the design. The new form of the kiln, containing cavity walls and increased air flow through the base, was finalised and a half-scale model was produced with the help of Dyson Centre technicians. This developed our capability to clearly communicate the overall concepts as well as the fabrication details. In addition, CFD was used to analyse the insulative performance of the combustion chamber. This served as a primary performance metric and comparison point against the old design and real test data collected in Kenya.