Performance in gripping and turning -a study in hand/handle effectiveness.

The biomechanics of the hand/handle linkage were studied to generate data for the optimal design of screwdrivers and other devices which are gripped and used forcefully against resistance. Comparisons were made between smooth and rough steel cylinders and a range of commercially available screwdrivers of varying size, shape and surface quality. None of the screwdrivers was significantly better for the exertion of torque than rough cylinders of the same mean diameter, nor was any worse than a comparable smooth cylinder. It is therefore concluded that for forceful activity the precise shape of the handle is unimportant, the effectiveness of the activity being limited by the size of the handle and the quality of the hand/handle interface.