Design and Fabrication of a Manually Powered Grain Threshing Machine for Sorghum Farmers in Plateau State

Post-harvest threshing of sorghum using traditional beating methods remains inefficient and physically exhausting for farmers across the Middle Belt region of Nigeria, resulting in significant grain losses and reduced market competitiveness. This study presents the design, fabrication, and performance testing of a manually powered sorghum threshing machine suitable for small-scale farmers in Plateau State. The machine consists of a rotating threshing cylinder equipped with wire loop pegs, a concave screen, and a hand-crank drive mechanism transmitting motion through a gear assembly to achieve the required cylinder speed. All structural components were designed using standard beam and shaft analysis, and fabricated from locally available mild steel using workshop facilities at the University of Jos. Performance tests were conducted using freshly harvested sorghum panicles obtained from farms in Barkin Ladi and Mangu local government areas. Threshing efficiency, grain damage rate, and throughput capacity were measured across three experimental runs. The machine achieved a threshing efficiency of 93.5 percent, a grain damage rate of 2.8 percent, and a throughput capacity of 95 kilograms per hour under continuous manual operation. Total fabrication cost was estimated at 41,200 naira, making the machine accessible to individual farmers or cooperative societies. The study recommends adaptation of the design for maize and millet to broaden its applicability across the North Central food production zone. Keywords: sorghum thresher, manual operation, threshing efficiency, post-harvest technology, Plateau State.