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Handling roller-press dies has caused numerous work-related musculoskeletal disorders in the leather industry. The dies are quite large (0.61 x 0.30 m), heavy (3.5 kg) and are difficult to handle because of the large pinch span requirements (up to 16 cm). The purpose of this study was to determine the optimum pinch span and optimum crossbar angulation to minimize die handling forces. Five-finger pulp-pinch forces were measured on five males and five females with a force-sensitive-resistor instrumented glove while handling a simulated adjustable die. Maximum pinch forces occurred at pinch spans between 1.27 and 3.81 cm, with average female strengths being 57% of average male pinch strengths. Minimum pinch forces to hold the die occurred at a 45 degrees angulation and increased linearly as the angle approached 90 degrees or the normal vertical orientation. The simplest solution to redesigning the dies is to: (1) decrease the distance between the braces to less than 4 cm and (2) slant the braces at 45 degrees. Keywords: Pinch forces; Pinch span; Musculoskeletal disorders; Roller-press dies

Reaction torque measures of six different nutrunners were correlated with EMG measures and subjective ratings of perceived exertion for different work surface orientations, joint stiffnesses, rpm levels, air pressure levels and handle configurations. Using an underpowered tool or using a softer joint resulted in larger impulses and worse ratings. A pulse-type shut-off mechanism produced the lowest reaction torque and the best rating. Overall, ratings correlated directly with the impulse level. The subjects were good judges of stress levels, and subjective ratings were valid measures of operator stress.