When you drive a fastener into material with a power tool, torque transfers to your hand when the screw or bolt bottoms out and makes your hand snap. Repetitive snapping motions can produce a great deal of stress and can cause injuries and illnesses when it happens on a regular basis. Power tools with an extra handle for your other hand help counter torque stress. And pulse tools, which stop rotating when the desired torque is reached, can also help reduce torque stress. This is the gain or loss of heat you experience through contact with the tool.
Heat transfer is a major concern for people who work in hot or cold conditions.
Stress and vibration have a more damaging impact when your body is already trying to compensate for environmental factors. Weight Heavy or unbalanced tools tire the upper arm and shoulder muscles, especially when the job task requires you to straighten your arm out. The amount of weight you can handle comfortably will, of course, vary from person to person. Handle Design Handles should be located close to the center of gravity of the tool. This reduces the chance of a tool slipping out of your hand.