Pocket tool gets a makeover

DN Staff

November 19, 2001

8 Min Read
Pocket tool gets a makeover

Portland, OR-Good looks may not be everything. Yet for products to stand out from the competition, looks do matter. Even Leatherman pocket tools, those icons of form following function, recently got a facelift for this very reason. On the company's new line of Juice tools, the familiar brushed steel exterior of previous models has given way to anodized aluminum in a rainbow of colors. "With the Juice, an appealing appearance was one of our top design priorities," says Ben Rivera, the senior product design engineer who created the new tools. The design also features a new contoured shape that, along with a compact 3.25-inch length, results in a pocket tool that actually lives up to its name.

Peel back the Juice's colorful exterior and rounded styling, and these new tools are still all Leatherman. As much as cosmetics count on increasingly crowded shelves, the new Juice tools still reflect all of the company's core engineering values. Utility, for one, means a lot to Tim Leatherman, who invented a way to put pliers in our pockets back in 1975 and founded the Leatherman Tool Group Inc. in 1983 to commercialize his idea. "It's better to have 15 useful features than 75 questionable ones," he says. And given the hard use the tools see in the field, ruggedness obviously matters too. Leatherman tools meet stringent mechanical performance targets that grew out of the original tool. "Tim is both an inventor and an engineer, so he scrutinizes every feature on every product to make it stronger and better," Rivera says.

The company also stresses a closer-than-usual relationship between design and manufacturing. Today, Leatherman says he still likes design engineers who can not only create concepts on paper, "but walk up to a milling machine and make the chips fly." Or as Rivera, originally a manufacturing engineer, puts it, "Everything we do is designed with manufacturability in mind." Innovation is the final piece of Leatherman's engineering equation. The company's engineers may focus on the seemingly limited world of folding pocket tools-all but one of them based on the original folding-pliers idea-but they still strive to innovate. "The last thing we want is for one of our competitors to come up with a feature we wish we had invented," says Tim Leatherman. If the proof of innovation is in patents, Leatherman Tool Group has done well. It has more than ten design and utility patents awarded and several more pending-most for the tools themselves but also a couple for knife sharpening equipment. If you prefer commercial success as the benchmark, the company has sold more than 20 million pocket tools, beginning at a time when the pocket tool market didn't really exist.

While the Juice line reflects all these strains of Leatherman's engineering tradition, it also embodies some additional challenges. For one, it has the added burden of meeting the new aesthetic goals. It has more compact packaging requirements than most of the other pliers-based tools. And with it's five related but distinct models, Juice forced the company to manage manufacturing complexity in ways that a single product doesn't require.

Make it modular. To reconcile all these design challenges, Rivera created Leatherman's first modular design. All five Juice models share a fundamental handle construction in which 0.025-inch-thick aluminum skins cover a 0.040-inch-thick stainless steel structural frame. Just two frame sizes can produce the whole line, even though each model sports a different combination of tools. Color alone differentiates the aluminum skins. The chief benefit of a modular platform is what Rivera refers to as "extensibility." The first Juice prototypes had few tools beyond the pliers-just a knife blade, screwdrivers and file. The modular platform allowed the easy addition of saws, corkscrews, awls, and scissors in different combinations. Future models could incorporate even more features.

From a materials selection standpoint, the modular design allowed Leatherman to move beyond the polished stainless steel exterior of earlier products. When Rivera first sat down to design the cosmetic skins, he cast the nets wide from a materials standpoint. "I looked at plastics, composites, and even wood," he says. Aluminum emerged as the winner. Rivera selected a 5052 grade because it takes well to anodizing and the blanking process. And at the same time, aluminum helped maintain Leatherman's product identity in a way that plastics or composites could not. "Metal gives the impression of robustness and quality that our customers value," Rivera says.

He had less flexibility in choosing materials for the frame: It had to stay in steel given the mechanical requirements for the tool, which are based on its solid-steel forerunners. "The original Leatherman still acts as a benchmark for mechanical performance," Rivera says. Like other Leatherman tools, for example, the Juice tool's handles have to withstand a minimum of 120 lb of squeezing force and at least 75 in-lb of torque when opened into a "T-shape" and twisted in a vise. Rivera notes that these targets are just guidelines. For instance, the Juice actually withstands more than 170 lbs in the squeeze test, while some other Leatherman models have no trouble exceeding 200 lbs. Rivera accounts for this discrepancy between the lower targets and higher actual performance not just in terms of a safety factor. The difference also encompasses a small subjective element of the tests-a gray zone between deflection and failure that varies with each tool's individual metallurgy.

Surprisingly, one thing that didn't play an explicit role in Rivera's materials selection was weight. "Weight requirements started as an issue in our first iterations, but we relaxed them to add more features," Rivera says. "It wasn't a primary design goal." All the same, Rivera did manage to take plenty of weight out of the new pocket tools. The Juice line covers a range from just 4.3 to 6.7 ounces, while comparably outfitted all-steel models weigh in at about an ounce more across the board. The use of aluminum contributed to some of the savings, Rivera says. So did the design of the steel frame. "We punched out any metal that wasn't doing anything structurally," Rivera says.

The close ties between design and manufacturing also paid off when it came to optimizing the size and location of these lightening holes. Rivera sometimes uses stress analysis software for this kind of work. But he and Tim Leatherman both express a preference for empirical testing. "We've used FEA in the past, but it takes me less time to build a model and load it to failure," Rivera says. For his part, Tim Leatherman jokes that he didn't do well enough in engineering school to use FEA.

Screws out. Juice also mark's a change in Leatherman's approach to fastening. Until now, the company held its tools together with threaded fasteners screwed into tubular pins that extended through the handles. The Juice line uses solid rivets instead. "The Juice tools didn't have room for the large holes required by hollow pins," explains Rivera.

The switch to rivets has implications beyond joining a bunch of parts. "Manufacturing with rivets is a lot more challenging," Tim Leatherman points out. Using permanent fasteners also makes repairs more difficult-a key consideration given Leatherman's 25-year warranty and the fact that its products aren't treated all that gently in the field.

Even more significant, fasteners have always played a role in how the Leatherman tools operate. As Rivera explains, past designs relied on the "squeezing action" of the screws to keep the tools closed until the user opened them. Without the screws, the Juice tools needed springs to retain the blades, much like a traditional pocketknife. "The springs did add some complexity to the design," Rivera concedes. On the plus side, however, the springs offer a more precise control of blade action than friction from the tightened screws. "On the original Leatherman it was tough to control how tight the screws were," he says. Springs, and the positive retention they provide, also made it easier to put the knife blades on the outside of the tool. "One roadblock to having blades on the outside of the tool has always been a lack of a way to control the blade retention," Rivera says.

Trimming costs. For all the benefits of the new modular design, the Juice did threaten to drive up manufacturing costs. The new design has more parts and takes longer to assemble than traditional Leatherman tools. And even though the modular handle design shares components among five distinct products, its separate frame and skin components still called for more tooling than a typical new product rollout. Together these factors threatened to add more than 20% to the usual manufacturing costs, according to Rivera.

The focus on manufacturing methods helped keep these costs from escalating. To make the skins, for example, Rivera found a design solution that allowed Leatherman to use conventional blanking instead of a more expensive fine-blanking process. In keeping with the high-end cosmetic goals, Rivera had considered the more expensive process at first: "It makes a nice, clean cut. The parts don't look torn out," he says. But fine-blanked parts would have cost about four times the piece-part cost of blanked components, so he ultimately rejected the process. Instead he designed a conventional blanked part whose edges are drawn into a rounded shape, hiding those edges in the finished knife. "They are drawn around into a radius so that that you can't see the cut," Rivera says. Beyond driving down cost, this method also let him get away with thinner skins. "With fine blanking, we would have needed a 0.065-inch thickness to get the same rounded effect," Rivera says.

If the Juice tools reveal anything about Leatherman, it's a willingness to try new things. Moving from the well-known turf of stainless steel to the unfamiliar terrain of aluminum required the company to adopt manufacturing processes with which it had no experience. Likewise the change to modular tool design and rivets forced the company into new manufacturing methods. "We always learn as we go along," says Tim Leatherman.

Sign up for the Design News Daily newsletter.

You May Also Like