What Should Tool Handles Be?

A tool handle is the part of a tool that is designed to be gripped by the user’s hand. Proper tool handle design is critical because the handle serves as the main interface between the human body and the tool. Well-designed handles allow the user to comfortably grip and precisely control the tool, while reducing fatigue and injury risk. Tool handles have a long history of evolution as humans have continually sought to improve their grip and control of tools.

The earliest known tool handles date back approximately 2 million years ago to the Oldowan stone tools used by human ancestors. These crude handles were wrapped in animal sinew, hide, or plant fibers to protect the user’s hand when using stone choppers and scrapers. Over the next million plus years, tool handle designs slowly improved as humans developed new techniques like carving, shaping, and polishing handles from materials like wood, bone, antler, and eventually metal. The precision, comfort, and sophistication of modern tool handles reflects hundreds of thousands of years of incremental handle improvements by innovative tool makers and users.

Ergonomics

Proper ergonomics is crucial for tool handle design. The handle needs to accommodate the anatomy and physiology of the human hand to reduce fatigue and potential injury [1]. Some key considerations include:

The hand has 27 bones, including the carpals, metacarpals, and phalanges. These bones allow a wide range of motion needed for grasping and manipulating objects [2]. The arrangement of muscles, tendons, and nerves enable complex motor skills. However, they can also be vulnerable to overuse injuries if the handle design places too much strain on them [3].

Tool handles should distribute pressure evenly across the palm and fingers to avoid creating pressure points. The grip span should align with the natural width of the user’s hand. Angles that cause awkward wrist positions or repetitive motions should be minimized [1].

Materials, contours, and coatings can enhance grip comfort. Shock-absorbing handles reduce vibrations transmitted to the hand. Proper sizing and dimensions enable a power grip without requiring excessive effort [2]. All of these factors can help reduce hand fatigue and lower the risk of conditions like carpal tunnel syndrome.

By considering hand ergonomics and avoiding design flaws that strain the hand, tool handles can provide maximum comfort, control, and safety for the user [3].

[1] https://www.researchgate.net/figure/Recommendations-for-hand-tool-handle-design-5_fig10_234056130
[2] https://go.gale.com/ps/i.do?id=GALE%7CA364502002&sid=googleScholar&v=2.1&it=r&linkaccess=abs&issn=17264529&p=AONE&sw=w
[3] https://www.researchgate.net/publication/260432579_Decision_Support_System_for_Generating_Ergonomic_Tool-Handles

Grip Types

There are several basic grip styles used for tool handles, each optimal for different purposes:

Power Grip: Curls the fingers and thumb around the handle, providing maximum grip strength for high force tools like hammers and axes. Preferable when applying lots of downward force or torque.

Precision Grip: Holds the handle between the thumb and fingertips. Provides fine motor control for detailed tasks using hand tools like screwdrivers, chisels, and planes. Preferable when accuracy and control are needed.

Pistol Grip: Positions the handle inside the palm with the thumb pointing forward along the handle. Provides good leverage and dexterity for one-handed tools like drills, circular saws, and jigsaws. Preferable for operating trigger-based power tools.

Writing/Artist’s Grip: Grips the handle between the thumb and side of the index finger. Allows fine manipulation required for pens, paintbrushes, and other crafting tools. Preferable when intricate motions and flexibility are required.

Choosing handle designs optimized for the intended grip style allows for safer, easier, and less fatiguing use of tools for specific purposes.

Handle Materials

The material used to construct a tool handle impacts comfort, durability, weight, thermal properties, and cost. Some key considerations for common handle materials include:

Wood – Traditionally used for tool handles due to its shock-absorbing properties. Wood is affordable, lightweight, and provides a good grip. However, it can crack over time and is not very durable. Types like hickory and ash are common.

Metal – Very durable but can transfer vibration and become slippery with sweat or oils. Metals like steel and aluminum are common. Steel provides strength while aluminum is lightweight.

Plastic/Rubber – Offer shock absorption but may not be as durable as wood or metal. Thermoplastics like polypropylene are lightweight, low cost options. Thermoset plastics like epoxy resin are more rigid. Rubber handles provide comfort but can deteriorate over time.

Composite – Combining materials provides an optimal balance of properties. Common composites are rubber overmolded onto plastic or foam cores. These provide shock absorption, grip, and weather resistance while minimizing weight.

According to this study, composites of EPDM rubber and EPDM or PU foam provide an optimal combination of shock absorption, durability, and ergonomics.

Handle Shapes

Tool handles come in a variety of shapes including round, oval, triangular, oblong, and others. The shape of the handle can have an impact on grip, comfort, and effectiveness for specific tasks.

Round handles are one of the most common and allow for a neutral grip. They distribute pressure evenly across the palm. Round handles work well for general tasks like hammers, screwdrivers, and shovels.

Oval or egg-shaped handles conform better to the natural shape of the hand. The oval shape provides more surface area and avoids pressure points in the palm. Oval handles are popular for rakes, garden tools, and axes.

Triangular handles fit into the V shape between the thumb and fingers. They provide good control for detail work like chisels or knives. The angles give leverage and prevent the handle from twisting in the hand.

Oblong or rectangular handles are flat on multiple sides. They allow for indexed grips and control of the tool orientation. Oblong handles work well for striking tools like mallets and axes.

Handle shapes can be optimized for specific tools and tasks. For example, a saw handle needs to allow wrist flexion, while a shovel handle should transfer force efficiently into the blade.

According to research by Dianat et al. (2015), triangular and oblong handles reduce muscular activity in the hand compared to cylindrical handles. The shape that optimizes grip and reduces fatigue depends on the specific demands of the task.

Handle Coatings

Tool handles are often coated in rubberized or textured coatings to improve grip and control. These coatings create friction against the user’s hand, allowing for a more secure hold on the tool (Piper Plastics). Common coatings include plastisol, rubber, thermoplastic elastomers (TPE), and polyurethane.

Plastisol is a thick liquid PVC coating that forms a cushiony, non-slip surface when cured. It offers excellent grip in wet or oily conditions. Rubber coatings like neoprene provide shock absorption. TPE coatings are flexible and resistant to oils and solvents. Polyurethane forms a durable, cushioned grip that maintains its texture over time.

These coatings are often textured as well, with crosshatched or diamond plate patterns molded in. This further enhances grip and control when handling vibrating, heavy, or slick tools. Properly coating and texturing a tool handle makes it more comfortable to hold and reduces hand fatigue and the risk of slipping (Thomasnet). Overall, handle coatings are a critical factor in tool ergonomics and safety.

Vibration Reduction

Prolonged exposure to vibrations from power tools can cause serious injuries like hand-arm vibration syndrome (HAVS). Tool manufacturers have implemented various design strategies in tool handles to help reduce vibration transmission to the user’s hands and arms.

One common method is adding rubberized coatings or grips on the handle. These absorb vibration and dampen vibration transmission. Handles can also be designed with internal dampeners or springs that isolate the user’s hands from vibrations.

Another strategy is incorporating counterweights inside the tool handle. As the tool vibrates, the weights move in the opposite direction and counteract the vibrations. Some tools even have active electronic systems that detect vibrations and generate counteracting vibrations electronically.

Ergonomic handle shapes that provide a secure grip also play a role. If the user has an unstable grip, more vibration will be transmitted to their hands. Proper hand placement areas on anti-vibration handles reduce transmitted vibrations.

Manufacturers continue innovating new damping technologies to minimize tool vibration. But users also play a role by choosing tools with effective vibration reduction and gripping tools properly. Following usage guidelines and wearing gloves can further help reduce vibration exposure.

Size and Dimensions

Proper sizing and dimensions of tool handles is critical for comfort and avoiding injury. The handle diameter should match the natural gripping diameter of the user’s hand. Studies show the optimal handle diameter is around 38mm for medium sized hands. Larger handles around 45-50mm suit larger hands, while smaller handles of 25-30mm accommodate smaller hands ¹.

The length of the handle should allow the user’s hand to wrap around it with the fingers and thumb able to meet or overlap slightly. Too short of a handle length prevents proper gripping and leverage. The optimal handle length considers the user’s hand size. For a medium hand of around 18-20cm in length, the handle should be around 12-15cm long. Shorter handles of 10-12cm work for smaller hands, while larger hands need handles of 15-18cm ².

Proper weight distribution and balance minimizes fatigue. The tool’s center of mass should align close to the handle center to avoid uneven weighting. Handles with light materials reduce mass, while thicker handles spread weight across the palm and fingers. Textured grips also help secure control during use.

Advanced Designs

Tool handle design has come a long way in recent years. New materials and innovative shapes are transforming traditional wood and plastic handles.

Some advanced handles now incorporate sensors and electronics. For example, Bosch created the Reaxx table saw that has handles outfitted with force sensors. These can detect dangerous kickback and automatically retract the blade to prevent injury. The saw handles integrate an advanced sensing system into a traditional handle shape (1).

Other companies are utilizing high-tech materials like carbon fiber and magnesium alloys. These provide exceptional strength and vibration dampening in a lightweight package. For instance, Stiletto produces titanium and carbon fiber hammer handles that are durable yet weigh ounces instead of pounds (2).

Ergonomic shapes are also an important innovation. Curved handles that better fit the hand, adjustable handles, and handles with tactile grip surfaces help reduce fatigue and injury. Stanley recently designed an award-winning tape measure handle using this human-centric approach (3).

While wood remains popular for its beauty and feel, modern handles are merging cutting-edge tech with ergonomic design. This evolution helps maximize tool performance while minimizing user effort and injury.

(1) https://www.boschtools.com/us/en/boschtools-ocs/reaxx-table-saw-saws-rls181x-33376-p/
(2) https://www.stiletto.com/tibones-titanium-hammers/
(3) https://www.stanleytools.com/press-room/stanley-black-decker-honored-three-prestigious-2017-good-design-awards

Conclusion

When it comes to tool handles, there are several key factors to consider for optimum design. Handle material, shape, size, coatings, and vibration dampening abilities all play an important role in ensuring comfort, control, and safety. Materials like rubber, plastic, and wood each offer unique benefits and drawbacks in terms of grip, shock absorption, and durability. Ergonomic contours and textured surfaces provide secure hold and prevent slippage. Proper sizing allows tools to be used safely and efficiently. Additional handle elements like gel pads or suspension systems help reduce hand-arm vibration.

Looking ahead, we may see more advanced handle technologies emerge. Areas like adaptive materials that conform to hand shape, active vibration cancellation, and integrated sensors could take handle design to new levels. However, the fundamentals of comfort, control and protection will remain paramount. With sound ergonomic principles and testing, tool handles can continue improving to best serve user needs.