Castor bean shelling machine is designed, fabricated, tested and evaluated to mechanically remove the shell of castor bean (Brazilian variety), an oil producer plant. Te machine was composed of seven major components: hopper, shelling unit, separating unit, seed outlet, unshelled seed outlet, frame, and v-belt & pulley transmission system. This study aimed to mechanize the time consuming and energy sapping traditional method of shelling castor bean. Physical and mechanical properties of the castor bean were obtained and analyzed for the design analysis and calculation of the machine components. Tree shelling
speeds (490-510, 590-610 and 690-710 rpm) were analyzed using Complete Randomized Design with three replications each. Results showed that shelling speed of 490-510 and 590-610 rpm was statistically the same in separation loss, unshelled loss, scattered loss, total losses, percent mechanically damaged seeds and shelling recovery. Te computed total annual cost was ₱123,679.10 which included fixed and variable costs. Based on the maximum capacity of 171,360 kg/yr, the unit cost of shelling was ₱0.72/kg. Te break even weight of castor bean was 138,000 kg. Te machine had a rated input capacity of 238 kg/hr and shelling efficiency of 90% with recommended speed of 490-510 or 590-610 rpm (8.78 m/s peripheral speed).