Adapting the force characteristics of a staple gun to the human hand

• Three modified staple guns are compared with a standard staple gun.
• A linearly increasing staple gun force curve is not optimal for a human hand.
• The muscular exertion is lowered with an adaption of a staple gun force curve.
• The tool efficiency is increased with an adapted force curve.

Three prototype staple guns with modified force characteristics were compared with a commercially available standard staple gun with a linearly increasing force resistance during squeezing. The force characteristics of the prototypes were more or less adapted to the force characteristics of the human hand, and in one of the staple guns the general force level was also reduced by one third. Evaluation instruments were electromyography of the forearm flexors and extensors, subjective rating of forearm exertion and subjects' free comments about the four tools. Twelve professional craftsmen were recruited as test subjects. The results show significantly lower readings for two of the three prototypes compared with the standard gun in electromyography as well as subjective ratings. The squeezing times are also reduced for two of the prototypes. It is concluded that the choice of force characteristics of a staple gun is important both to minimize forearm muscular exertion and to increase tool efficiency.