Selecting Hand Tools

Some tools are designed with ergonomic features. A tool becomes ergonomic only when it fits the task and fits the hand of the worker using it without causing awkward postures, harmful contact pressures or other safety and health risks.

If a tool does not fit the hand, or the tool is used in a way it was not intended, injuries (such as carpal tunnel syndrome, tendonitis and muscle strain) can develop. These injuries do not happen because of a single event, such as a fall. Instead, they result from repetitive movements that are performed over time. Such repetitive movements can result in damage to muscles, tendons, nerves, ligaments, joints, cartilage, spinal discs or blood vessels.

A worker may have an injury if they have any of the following symptoms: tingling; swelling in the joints; decreased ability to move; decreased grip strength; pain from movement, pressure or exposure to cold or vibration; continual muscle fatigue; sore muscles; numbness; or a change in the skin color of the hands or fingertips. These symptoms may not appear immediately because they can develop over weeks, months or years; by then, the damage can be serious.

Workers need to take action before they notice any symptoms. Before selecting a tool, the worker should think about the job. Tools are designed for specific purposes - using a tool for something other than its intended purpose could cause pain, discomfort or injury, as well as damage to the tool.

• For single-handle tools used for power tasks, does the tool feel comfortable and have a handle diameter between 1-1/4 and 2 inches (3.2 and 5.1 cm)?
• For single-handle tools used for precision tasks, is the handle diameter between 1/4 and 1/ 2 in (0.6 and 1.3 cm)?
• For double-handle tools used for power tasks, is the grip span at least 2 in (5.1 cm) when closed and no more than 3-1/2 in (8.9 cm) when open?
• For double-handle tools used for precision tasks, is the grip span no less than 1 in (2.5 cm) when closed and no more than 3 in (7.6 cm) when open?
• For double-handle tools, is the handle spring-loaded?
• Is the tool handle without sharp edges or finger grooves?
• Is the tool handle coated with soft material? Adding a sleeve to the tool handle pads the surface, but also increases the diameter or the grip span of the handle.
• Can the tool be used while keeping your wrist straight? Tools with straight handles are better than those with bent handles when the force is applied vertically.
• Can the tool be used with the dominant hand or with either hand?
• For high-force tasks, is the handle longer than the widest part of the hand? Contact pressure can be prevented by making sure the end of the handle does not press on the nerves and blood vessels in the palm of the hand.
• Does the tool handle have a non-slip surface? A tool that has a non-slip surface provides for a better grip. Adding a sleeve to the tool improves the surface texture of the handle. To prevent tool slippage within the sleeve, the sleeve should fit snugly during use.

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