A practical method for ergonomic and usability evaluation of hand tools: a comparison of three random orbital sander configurations.

Tool and equipment purchasing decisions are constantly made by companies and workers, often with little objective information beyond word of mouth and marketing information. This study presents a pilot investigation of random orbital sanders using ergonomic and usability assessment techniques which can easily be applied in any industry. Three subjects performed a sanding task using three different tool configurations: 1) the current model sander, 2) current model with hose-swivel attachment, and 3) the new "ergonomically designed" model. Physical measurements were taken of muscle activity and wrist motion to complement think-aloud testing and a usability questionnaire. No significant differences were found in physical measurements between the three configurations. Participants strongly preferred the current model over the new model, reporting less perceived discomfort and vibration, despite what appeared to be improvements in the new design. Workplace changes intended to reduce the risk of injury sometimes may have no effect after significant capital investment, or in some cases even increase the risk of injury. Practical assessment of new tools or modifications can quickly determine whether the outcome is indeed an improvement. The results of this tool assessment highlight the need for objective information in tool and equipment design decisions.