Power tools must perform tough tasks; designing them is a tough task, too. There aren’t many products where bad design can actually hurt the user, so good power tool design is more than just a desirable option, it’s an absolute necessity.

What makes the task so challenging is the host of design imperatives that each demand center stage in the process. Individual product style, brand identity, human factors, technical requirements, safety considerations—all must be melded together into a compact package capable of being held by the human hand.

The competing imperatives make designing a power tool a perfect exercise in design, but it’s no game. The power tool business is a highly competitive market worth tens of billions of dollars globally, a market where new customers are hard to win over, and where old customers can be quickly lost. It’s a product segment where the tiniest ergonomic detail can delight or annoy a person who must use the product for extended periods of time.

Invention vs. innovation

As with many other products, the design effort is often initiated by the marketing team. Sometimes market research identifies a product gap that can be filled. For example, the DeWalt 10 kg. demolition hammer was created to provide something between a smaller hammer drill and a larger pavement breaker.

At other times, an opportunity may arise for a whole new category of product to be created. Such was the case when cost and size of laser leveling technology came down as the robustness went up, allowing power tool manufacturers to add laser levels to their line.

In these cases, the design process begins with a clean sheet aimed at the invention of a new product. More commonly, however, the process is focused on bringing innovation to an existing product. Such redesign efforts may be fueled by the philosophy of continuous improvement, user feedback about a specific features, competitive benchmarking, safety trends and standards, or simply a perceived need to reinvigorate a product that hasn’t been updated in a while.

As with most product development these days, the effort requires the collaboration of designers, engineers, and marketing people, all working together and exchanging ideas, either formally or informally. The old notion of one discipline doing its part, then tossing it over the wall to another discipline, is avoided. That said, however, there is still typically an implicit hierarchy of issues.

For example, if a critical goal for a new cordless power tool demands certain level of power, that goal may dictate motor size and weight, as well as the size and weight of the battery pack. In such cases, the project must begin with the technical constraints clearly understood.

In a different scenario, say the redesign of a tool with the intention of making it easier to use, the ergonomics may be the starting point.

Snap-On Tools cordless driver/drill model was targeted at the auto mechanic segment, so the tool was given a soft-edge style that would resemble the shapes of cars the mechanics would be working on. The “turbo bulges” on the housing represent one of the visual design elements intended to evoke an automotive aesthetic.

“We work out the ergonomics first before starting the actual styling of a power tool,” says Rainer Schnabel, executive vice president at Brooks Stevens Design, Grafton, Wis., whose clients include Milwaukee Electric Tool and Snap On Tools. “We avoid showing the client pretty pictures of concepts too early, because we don’t want them to fall in love with a visual design and run with it before we have validated the ergonomics of the design.”

Often a project will have a checklist of priorities or “must-haves” that define the direction of the design effort.

“There is a hierarchy of elements a DeWalt power tool must have before it can receive final approval for production,” says Robert Welsh, director of industrial design for the DeWalt line of power tools made by Black & Decker, Towson, Md. “We call them CTQs, things critical to quality. Each one has to be checked off, and, if one can’t be, then the issue has to be addressed before production.”

Pro vs. consumer

The compilation of design objectives will be driven primarily by the needs and desires of the target market, the crucial distinction being whether the user is a professional or consumer. The most obvious difference between the two types of products is durability. The professional power tool may be used four to six hours a day, logging more hours in a week than a consumer tool may see in a year. More importantly, professionals make their living with their tools; downtime can be costly.

DeWalt demolition hammer was designed to keep the axis of force in line with user’s arm to offer better control and decrease stress on the wrist. To reduce user fatigue, the tool utilizes both active and passive vibration control measures. Visually, the design synthesizes both soft curves and hard lines. The handle curves suggest user friendliness, while the motor vent rib lines evoke a sense of power. The vent ribs also serve functional purposes, adding structural rigidity and providing a place to exhaust motor heat.

Professionals and consumers make their power tool purchase decisions differently, too, which therefore, affects the whole marketing approach.

“It’s the difference between using either a push or a pull marketing strategy,” says DeWalt’s Welsh. “Take the Black & Decker Snakelight, a consumer product. Nobody ever asked us for that. It was just a neat idea we came up with, which we then promoted. And we sold gazillions of them. That’s an example of a push strategy, which is what you do on the consumer side. By contrast, we use a pull strategy for DeWalt, where we are targeting the professional who makes a living with our product, not the weekend warrior who wants the latest, greatest thing to hang a birdfeeder. For DeWalt, what we do is listen to our professional customers, then give them what they ask for. They pull it out of us.”

The professional power tool user typically exhibits a lot of brand loyalty and purchases according to need. As a result, professionals make planned purchases. They typically go shopping with a specific tool and brand in mind. By contrast, the consumer power tool user exhibits less brand loyalty, can be more heavily influenced by a point of purchase display, and more likely to make an unplanned purchase. These differences, subsequently affect design.

“The consumer power tool market is much more open to new ideas, innovations, trendy styling and colors, much like the consumer electronics market, where it’s all about having the latest new thing,” says Paul Hatch, president of TEAMS Design, Chicago. TEAMS Design, which also has two offices in Germany, has been designing professional power tools for Bosch for decades. When Bosch bought the Skil line of consumer power tools from Emerson, TEAMS became involved on that side of the business, as well.

“The professional market is much more skeptical of what you’re trying to sell them,” Hatch says. “Professionals don’t want in-your-face styling. The aesthetics require a certain understatement. And professionals don’t want gimmicks, either. For example, we came up with an idea for a magnetic plate to go on top of a drill-driver to hold screws and bits, because we’d observed people sticking these things in their mouths as they climbed ladders and so forth. It was a useful idea, but the professionals found it too patronizing and gimmicky. The idea eventually ended up on a Skil cordless drill, though. So it was a useful consumer idea, but not for professionals.”

In a nutshell, the designers have learned that, while the consumer will buy revolution, the professional prefers evolution.

Image and brand

To an outsider, it may seem incongruous or foreign to apply the concept of aesthetics to something so purely functional as a power tool, but it’s not. First of all, with power tools, as with tools in general, the functionality is the beauty. Like a Swiss Army knife or a Leatherman multi-functional pliers tool, a power tool can inspire fascination with its capabilities, an emotional response that plays on the same chord as the response to beauty.

DeWalt’s Welsh offers another analogy. “To the average individual, a backhoe may not seem like a beautiful product. But if you need one, and you know how to use one, and know all the different things it can do, then, for you, it becomes a beautiful thing.”

But even beyond that, designers will still strive to impart a sense of style to a power tool product. Again, the outsider might ask: why would a drywall hanger care about style of his power tool? For the same reason he cares about what kind of pickup truck he drives. He cares about his image, both his own self-image, and his image in the eyes of colleagues. And his power tools reflect that image, as does his truck. The makers of power tools, like the makers of pickup trucks, spend a lot of careful thought on that image.

That’s why a lot of styling revolves around reflecting a brand identity, one that can be imparted to a wide variety of products of various sizes and functions. In addition to a distinctive logo, the most obvious brand identifier is a signature color scheme. DeWalt’s yellow and black. Bosch’s blue, black and grey, with red accents. Milwaukee Electric Tool’s red, grey and black.

Achieving those signature colors is not necessarily a simple matter, either. First of all, the given color has to be of a specific shade. It can’t just be any yellow, any blue, or any red. Secondly, and more challenging, is that the color often must be matched across different materials. A particular power tool, for example, might require color matching across two different engineering resins and a coated metal casting, all on the same product. And once in the field, the colors on that product should not fade, or, if they do, they must fade at the same rate. Unequal fading of a signature color on different parts can create a perception of lower quality, even though the durability of the parts is not actually affected.

Care must also be taken to protect the brand name on the product. The durability of the company’s logo reflects on the durability of the product. Power tools take a lot of abuse in the field. A logo that is easily scuffed or peeled off can reflect poorly on the manufacturer.

“How the logos are placed makes a big difference,” says Scott Micoley, design manager at Brooks Stevens. “You want to recess it or integrate it in such a way that it doesn’t get scraped when the tool is laid down or dragged across a surface. You can also use bumpers to shield the face of it, or even cover it. Obviously, the materials used make a big difference.”

Beyond colors and logo, there are other design elements that can be used to reinforce brand identity.

“We have a pretty tight trade dress established,” says DeWalt’s Welsh. “It’s more than just the yellow and black, it’s also the architecture and the geometry. We have trademarked signature elements that are employed regularly across the line. The consistency of a family look is just as important to us as it is to BMW or Mercedes. Our demolition hammer may be an entirely different product than a drill, but it is still clearly identifiable as a DeWalt.”

Further illustrating that point is the Perceptive Brand Recognition Test, described by Hatch of TEAMS Design. The firm employs the test as part of a new tool’s development process to ensure brand continuity. “We remove the labels and logos from our prototypes, then do the same with samples of competitor products, then paint all of them grey. Then we ask users to try and identify the different brands. If the majority of them are able to correctly identify the Bosch tool, then we know we’ve attained the certain ‘Boschness,’ despite having taken the styling further.”

Which raises another issue: How to balance the desire for a family look with a tool’s functional identity. The tool has to reflect what it does. A drill can’t look like a hair dryer.

“That’s often a difficult balance to achieve,” says Hatch of TEAMS Design. “We try to hit the sweet spot. What makes it harder is that it may not be enough just to make a drill look like a drill. Sometimes there is a sub-agenda. For instance, we designed a drill that you could drop off the roof of a three-story building. That was the unique idea behind it, the selling point. So the image had to reflect that aspect. The tool had to look tough like a truck, but, at the same time, not too bulky for the person to use.”

At TEAMS Design, the designers find it useful begin a project by thinking about adjectives. They ask the client what sort of adjectives they would use to describe the product they want. They then work to translate those adjectives into design elements.

For example, take the word “robust.” That might be expressed by large open surfaces, bulgy surfaces or forms, fewer lines, raised surfaces, bumpers, and big, bulky knobs and control elements. “SUV styling has become very stereotypical of that aesthetic,” Hatch says.

On the other hand, a different tool, say a router, might need to speak the word “precision.” That could be expressed with fine visual detailing, geometric shapes, parallel lines, a housing that tightly wraps internal parts, and small, tweaking knobs.

Another consideration when pondering power tool “style” is how much attention to pay to design trends in other arenas, such as automotive, where years of soft-edged organic shapes are yielding to crisper lines and occasional boxy shapes. Designers of power tools pay attention to those trends, but don’t necessarily slavishly follow them.

“The outside styling traits that affect power tools are long term styling traits,” says Hatch. “So when looking at other products, you have to define what is a long term styling element vs. a short term styling element. If, a few years ago, we had started putting translucent materials on power tools because Apple did it with the iMac, that would have been shortterm thinking, because it was a short-term trend.”

In one case, designers at Brooks Stevens deliberately imbued a Snap-On Tool drill-driver with an automotive aesthetic because the power tool was being designed specifically for auto mechanics. “We gave it a relatively soft design that was typical of cars at that time,” says Schnabel. “We put these elements on the outside, which we called ‘turbo bulges,’ while trying to minimize the size of the housing. It resonates well the users in the target group because it reflects the style of the cars they are working on with it. But even though it is a soft design, it still looks durable.”

And with hard vs. soft, it’s not necessarily an either/or proposition.

“You can have something soft in overall shape, but still bring crispness into it with a few breaks in textures, design details, vent lines, or lines in a hand grip,” says Micoley at Brooks Stevens. “Its about finding the right balance to achieve the emotional response you’re looking for.”

It is also worth noting that the discussion over hard vs. soft lines can also impact a power tool’s durability, given how frequently they will be dropped.

“A sharp, boxy corner takes a hard impact,” Micoley notes. “Whereas a rounded corner distributes the stress load over a wider surface area.”

The human touch

DeWalt 18V cordless reciprocating saw illustrates how visual cues are used to help make operation more intuitive, such as suggesting recommended grip areas. The black, textured, soft-overmolded area towards the front tells the user that support from the second hand can be applied either underneath or on top of the tool. Other human factors elements include a quick-change blade system that eliminates the need to touch a hot blade, and open-top shoe to improve visibility of the cutting area. The saw also demonstrates how the cordless revolution has made the battery pack an important design consideration, since its shape and weight affect the balance of the tool. Battery pack design becomes even more important when, as in this case, the pack is designed to be interchangeable with other cordless tools using the same voltage.

The manner in which a power tool is used makes human factors a critical issue in its design. The user must grip the tool tightly, exert a pushing force on it, and accurately control its movement. The tool will be held in a right hand, a left hand, a sweaty hand, a cold hand, and a gloved hand. It may be used down, sideways, or up over the head, held by extended arms. Depending on the application and the user, the tool may be used intermittently, or it may be used continuously for eight hours straight.

This makes the ergonomics of the power tool handle, the intimate point of contact, a high priority. In this field, a product can live or die by its handle. It has to provide a good grip and a good fit, but, not too good.

TEAMS Design’s Hatch notes that features such as finger grooves that allow the hand to perfectly fit a handle may seem like a good idea at first glance, but can turn out to be a mistake if they dictate how a tool should be held.

“We’ve noticed that, when people start using a tool with one grip, within 30 seconds, they will slightly change the position of their hands or fingers,” Hatch says. “They do it instinctively to avoid cramping. So the danger of finger ridges is that they can be too confining, prohibiting hand shifting, and possibly causing cramping. Another reason is that people need to grip a handle differently for different angles and positions. You need to preserve that flexibility.”

While getting a grip on handle design is crucial, it is not necessarily mysterious. Most power tool companies have been around a long time and have a legacy of knowledge to draw upon. Black & Decker, for example, has been making drills for 85 years. There are also a number of standard reference guides containing anthropometric data for designers to look at, though most designers in this area regard the data references as guidelines rather than dogma.

There are also technical research methods for studying grips, using moldable materials or pressure-sensing films to determine where the pressure points are. But the best source of information is the professional, the hard core user of power tools. Talking to them, watching them use power tools, having them grasp models and test prototypes, these are the research activities that yield the most fruitful insights into the design of a handle and the tool as a whole.

Once you’ve got your perfect handle model, however, you need to ensure that shape gets perfectly carried over to the production version.

“It’s very important how that form study model gets translated into 3D CAD geometry, which will be used to generate the tooling data,” notes Micoley at Brooks Stevens. “The slightest changes can compromise the ergonomics of the design. So we do a lot of careful measuring, and often laser scanning, of the original study model, to get that shape into the 3D CAD system accurately. Once we have the CAD model, we then bring that into our in-house CNC prototyping equipment to cut out a validation model. We then compare the surface geometry of the original and validation models to make sure nothing was lost or changed.”

Attaining the proper fit and feel of the handle is a key factor, but not the only one by any means. Other important human factors include the tool’s weight, balance, actuator location, force required for actuator, vibration level, noise level, sight lines to the point of work, where the chips fly, and whether the vents blow air onto the hands or face. Problems in any one of those areas can foster a negative impression of the tool in the eyes of the user. All of the human factors have to work together to help the user get the job done with a minium of discomfort.

It helps, too, that most people behind the design of power tools are adept with their use.

“You gain a tacit knowledge of a product by using it,” DeWalt’s Welsh says. “When you actually use a dry wall sander over your head, you can learn about a possible blister zone you might not otherwise have found.”

When Brooks Stevens Design was working on a hammer drill project, the firm had 6,000 lbs. of concrete block delivered to its parking lot and made everyone involved in the project use the tool for extended periods of time to test the tool’s ergonomics and fatigue factor. In another project, the firm built a mockup of a home construction site to test what it feels like for a plumbing contractor to crawl into an awkward space and use an auger to cut out 4-in. holes for PVC drain pipe.

The professional user, however, still remains the most powerful source of intelligence on power tools in terms of what works and what doesn’t, what feels good and what feels bad. Sometimes this means interviewing professionals, sometimes it means going to their workplace and quietly watching them work. Observation can yield a trove of insights, particularly when compensatory behaviors are discovered.

Compensatory behaviors can take a couple of forms. One is where users modify the expected technique for using the tool to compensate for some perceived shortcoming. In the other case, users modify the tool itself.

An example of the first type was found by Milwaukee Electric Tool while studying the use of routers by cabinet makers. They noticed that the cabinet makers were not actually using the handles provided on the routers. Instead, they were wrapping their hands around the motor housing, grasping the axis of torque to gain better control over the tool. Brooks Stevens employed that new knowledge in the design of a new router for Milwaukee Electric Tool, designing the router so that the motor housing would safely and comfortably accommodate the users’ hands. That feature, along with some improvements in the height adjuster, turned the new product into a big seller in a product arena where the company had previously been a marginal player.

An example of tool modification was found by Brooks Stevens researchers visiting a factory and noticing that users of air-powered assembly tools had wrapped the handles with foam, tape, or other materials. The reason? Compressed air is cold, and the constant flow through the tool made the handles frigid, chilling the users’ hands.

Another essential aspect of human factors is cognitive ergonomics, designing the power tool so that, as much as possible, its proper use is intuitive. This is important for consumer power tools, which may be used only occasionally, but also matters for professional tools used in factory settings or rental operations where the tool’s user is not the tool’s owner.

Providing visual cues is an effective means of communicating how a tool should be used. A common example is indicating suggested grip places by color, textures, bumps, the use of soft, overmolded elastomers, or all of them together. Such designated zones tell the user that it’s useful and OK for a hand to be placed there.

Safety first

Bosch circular saw features a low-resistance retracting guard so as not to interfere with cutting operation, even on thin veneers. This makes it less likely for a user to want to disable the operation of the guard, and serves to illustrate an important consideration for power tool designers: how to design safety features that won’t irritate the user and motivate him to circumvent the feature. Other attractive features include good balance, a hanging hook, and a direct-connect socket so that the user can plug his job-site extension cord directly into the tool.

Safety, of course, is a paramount consideration in the design of power tools. The potential for maiming by bits and blades leaps out as the most obvious danger. Less obvious, but possibly more common, is the threat of electrocution from power cords that get cut or pulled out of the tool’s housing. And sometimes the power tool may be the instigator of a chain reaction, where the initial injury or shock is mild, but causes the contractor to fall off a ladder or roof, which subsequently causes a more serious injury. It also bears noting that a power tool can be a potential hazard even in its passive, inactive state. Given its weight, the mere falling of a power tool off a ladder or ledge can injure someone below.

All power tool manufacturers have extensive safety review processes in place to identify and anticipate potential safety problems before the tool ever hit the market. A company has a variety of resources to provide insight on safety issues: its own history of making and selling tools, the agency approval process, input from professional users, input from professional ergonomists, testing, benchmarking the competition, previous litigation, and injury reports from the Occupational Safety and Health Administration and the Consumer Product Safety Commission.

The biggest challenge for the designer is how to implement a safety feature in such a way that it does not irritate users, thereby inspiring them to thwart the safety feature. For example, when observing job sites, it is common to find some contractors with saw guards taped up, tied up, removed or otherwise disabled.

One way to deal with the problem is to minimize the incentive for the user to thwart the guard by addressing his reason for doing it.

“Our approach is to make a guard as unobtrusive as possible,” says Hatch of TEAMS Design. “If visibility is the reason for tying up the guard, then we try to improve the sight lines. On a circular saw, where the guard is spring-loaded and retractable, the user concern is over the resistance the guard causes during the cut. So we designed a guard that retracts so easily, its presence isn’t noticed, even when cutting a thin veneer.”

Another approach is to build in anti-thwarting features.

“We try to design a tool so that safety guards can’t be overcome,” says Micoley of Brooks Stevens. “We worked on a miter saw design where we provided some internal linkages so that the switch can’t be activated if the guard is lifted out of the way.”

But in spite of designers’ best efforts, one thing remains unalterable. Even with the safest, most user-friendly design possible, safe and proper operation of a power tool still depends on the user, just like a car, barbecue grill, and countless other products.

Tool of the future

Bosch 12-in. miter saw illustrates the effective execution of an enormous design challenge: how to integrate an extremely complex set of parts together into a coordinated, user-friendly package. The miter saw is an example of a tool whose design language must express the concept of precision, as opposed to other tools whose primary expression is robustness. The two concepts are typically in opposition from the standpoint of visual design elements. User-friendly features include extra-wide extensions of the table surface and placing the controls on the user side

Given that power tool design revolves so heavily around functionality and human factors, one might reasonably wonder whether they will ever reach a state of perfection, where the fit, form and function characteristics become as good as they can possibly get. After all, the drill has been around for more than 85 years, can there really be any more to say or do with a drill? The short answer is yes.

“There is always something new to learn,” Welsh says.

Also, the competing imperatives in the development of a power tool means that there always necessary compromises in design, preventing the creation of a perfect tool.

“There are always some objectives not perfectly met due to the limitations of existing technology and materials,” says Schnabel at Brooks Stevens. “For example, you cannot increase power in a cordless tool without increasing its weight. So you have to compromise. But as both technology and materials improve over time, you are allowed to get closer to the ideal.”

And even slight changes in technology can have large impacts on tool design.

“When you increase the power of a cordless tool, you put in a bigger motor on one end, which then requires a bigger battery pack at the other end,” notes Hatch at TEAMS Design. “That shifts the whole balance of the tool, which in turn, changes the pressure points on the hand. And that requires you to address the ergonomics all over again.”

On the horizon, designers see technology improvements in motors, rechargeable batteries, and electronic controls, as having the greatest impact on power tool design.

Hatch identifies security concerns as another influence. “Power tools are very easily stolen from a job site, and that’s a growing concern to the professional user. I predict anti-theft features will represent a significant new trend in the future. I think different manufacturers will employ different methods to achieve this.”

That observation illustrates perfectly the philosophy that fuels innovation—identify a problem, then turn it into an opportunity. And the efforts of power tool manufacturers to seize those opportunities should keep their designers busy for a long time to come. —Richard J. Babyak

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