Design of a human powered maize mill

Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, February 2014.Cataloged from PDF version of thesis.Includes bibliographical references (page 25).The process of milling corn into flour in many rural communities of East Africa has remained a traditional mortar and pestle process for centuries. Milling machines have failed in these communities largely due to poor performance, as well as high cost, and as a result the incredibly labor intensive process continues. This study seeks to design and manufacture a prototype mill that will address the needs of the communities in question. Initial testing on existing milling equipment generated a quantitative understanding of the strengths and shortfalls of the available machines, and informed the design of a new mill. Once the design specifications were determined, a two stage, "twinmill" incorporating a stock low cost mill performing an initial coarse grind and a second identical mill that used modified grinding plates to produce finer flour was built. As expected, the two stage solution outperformed the existing machines by a significant margin: the acceptable flour yields rose from the 30-40 percent range, to consistently in the mid 60s. After subsequent modifications to the fine pass machine grinding plates, yields rose even higher, to an average of about 80 percent.by Melvin Gustavo Salinas.S.B