Design for Purpose: Setu

from Herman Miller

Purpose: To bring ergonomics to everyday seating

During their six-month tour to promote Mirra, the task chair they designed in 2003 for Herman Miller, the four principals of Studio 7.5 did a lot of sitting. Some of it was in the Mirra, of course, demonstrating its mix of active and passive ergonomics. But most often it was in multipurpose chairs in conference rooms and reception areas, airport lounges, and cafés. Before long, the Berlin-based quartet realized something: the seats in these temporary places, where one might spend anywhere from a few minutes to a few hours each day, were uncomfortable. Really uncomfortable. They pushed your body into unnatural positions. They were made from nasty materials. And their idea of movement was either a teeter-totter back that threatened to provoke motion sickness or a lever system so complicated that you wouldn’t bother to use it.

The 7.5 team—Claudia Plikat, Burkhard Schmitz, Carola Zwick, and Roland Zwick—asked themselves how this had come to be. How had multipurpose chairs, which were supposed to be everything, ended up being nothing? They decided to fix that. “For us, it became the holy grail—to create a continuous seat-and-back frame that at the same time allowed you to recline,” says Schmitz. “It would be combining the ultimate in aesthetics with the ultimate in function.”

Five years later, the process has come full circle, with Herman Miller debuting 7.5’s Setu line this month at NeoCon. Named after the Hindi word for bridge, the self-adjusting chairs are elegant and ergonomic, offering a recline of up to 26 degrees. They contain 48 percent recycled content and no PVC. But most notably, they also reinvent basic chair mech­anics, using mathematics and materials, including a biomorphic frame, to replace traditional tilt mechanisms.

The designers began their quest quietly, self-financing their research for the first 18 months. When they thought the idea was mature enough, they shared it with Don Goeman, Herman Miller’s vice president of research, design, and development. “Don said, ‘Get a life!’” Schmitz laughs. “Then he said, ‘You’re crazy!’ How did we overcome it? Because we are stubborn times four! And we are German!” (“That’s a little out of context,” Goeman clarifies later, chuckling. “I said that because they had slaved over Mirra, went off to support it after its launch, and right away were ready to start another chair. It was, Geez, please enjoy the fruits of your labor and take a vacation!”)

Jokes aside, Setu appealed to Herman Miller, dovetailing with the company’s own observations about how technology was changing where people worked. With the advent of Wi-Fi and BlackBerrys, “We’re not at our desks much anymore,” says Jack Schreur, Herman Miller’s lead for North American seating. Then there’s the continued blurring of office and home. The trend requires a new kind of furniture that combines the utility of contract pieces with the looks of residential offerings.

From the outset, function determined Setu’s form. At its crux is the kinematic spine: two open-sided, curving beams that run along the seat back and dip underneath the pan. A proprietary technology developed by 7.5, it was inspired by the human backbone and widens from the middle of the chair’s frame to its haunches. The rigid yet flexible polypropylene-and-glass composite supports the sitter’s weight and gently forces him into an ergonomic position. Inside the spine are vertebraelike spokes cast from a mixture of polypropylene and rubber; they allow the seat and back to move in a synchronized motion, keeping the movement fluid and jolt-free. Lyris, a woven suspension material that grew out of Herman Miller’s fabric explorations for the Aeron and Mirra chairs, connects to the beams on two sides. It works with the frame to support and cushion the sitter, and allows for a fully breathable back and seat.

The designers determined the shape of Setu’s frame by prototyping it, cranking out models on a CNC machine and puzzling together others by hand. They produced dozens of variations of the spokes’ angles and length, eventually using computer modeling to keep track of them. They calculated the frame’s ergo­nomic curve by having each studio member sit in it. “We have the advantage of being four people of different heights, widths, and genders,” says Carola Zwick. “If the seat manages to fit all of us, we have most sizes covered.” Then they tweaked the results with finite element analysis. And during it all, they worked closely with Herman Miller’s engineers, who “tortured” the chair, according to the designers, putting it through a battery of tests to ensure it would outlast the company’s 12-year warranty.

Once the frame was set, the rest was an exercise in reduction. Studio 7.5 wanted Setu to be lightweight, transparent, and environmentally friendly. The first aim was easy: avoiding an underseat tilt mechanism shaved 20 pounds off the chair’s weight. The second, a little trickier, was solved by making every element of Setu visible to the eye. The third, a concern close to the designers’ hearts, was satisfied by specifying green materials and production methods. As a result, Setu has only 16 parts, weighs less than 20 pounds, and is 92 percent recyclable.

Yet one hurdle remained: how to manufacture the chair. That biomorphic spine, so elegant in principle and practice, was the sticking point. Since it is multimaterial, it requires several injections during the molding process, with each substance heated and cooled at different times. Given the chemical nature of the plastics and the chair’s exposed form, there could be little room for error. “Every surface had to be perfect because everything was on view,” says Schreur. “That put an enormous amount of pressure on each individual part and how those parts were made.”

With sweat, savvy programming, and the use of one of only two gigantic rotary-mold machines in the United States (christened “Stargate” by 7.5), Herman Miller found its answer. From there it was gravy. “Once you get that spine made, the chair becomes easy to produce, which also makes it more affordable,” Schreur says. The machine contributes to cost-efficiency by simultaneously manufacturing kinematic spines of varying sizes without retooling or interrupting the production flow.

That last detail is critical. Since all of Setu’s intelligence is in the seat frame, which can be scaled up or down according to application, the form is unaffected by what resides below it. (“You want to mount it on concrete? We could probably do that,” Schreur assures. “You want to put it in a tandem setting? We can do that because we have.”) Herman Miller will initially offer Setu with a five-star base on casters and a four-star one on glides (both will start in the mid-$600 range) as well as in a lounge version with an ottoman (around $1,100 and $500, respectively.) The company is also readying stool and wire-base models for the fall and plans to introduce stackable and other four-legged takes next year.

If the market for no-muss, no-fuss, multipurpose seating is this extensive, why did it take so long for someone to address it? Schmitz cites two things in short supply now: resources and courage. “The solution we have now is very simple, it looks simple, but to manufacture it needs a lot of investment,” he says. “We don’t think we could have persuaded anyone but Herman Miller to take that risk.”

Design for Purpose:

Whitelines: Sketchbooks for persnickety designers

Setu: To bring ergonomics to everyday seating

Generation by Knoll: Task chair for the younger set

Handle Easy: Cell phones for seniors

Custom Flooring: Carpet produced on demand

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