I, Robot
Advanced CNC fabrication allows builders to go bigger. Jeff Byles looks into how much.
The German-made robot at the Swiss Federal Institute of Technology has even mastered the art of bricklaying.
Courtesy ETH Zurich

N estled high in the Swiss Alps, the tiny commune of Évolène is an unlikely place to find futuristic architecture. But there, amid rustic chalets and snow-capped mountains, is the unfolding saga of François Roche and his competition-winning scheme for a museum of ice.

The brief called for an exhibition space-cum-shrine to commemorate the region’s retreating glacial landscape. Roche, with his Paris-based firm R&Sie(n), proposed a structure of bladderlike forms evoking ice cavities. Like most architects today, Roche could order up a scale model of this swooping confection on a computer numerically controlled (CNC) milling machine or a three-dimensional printer. But to actually build this beast? Thus began Roche’s adventure into the future of digital architectural fabrication.

The future, as it happened, was not far away. Roche turned to a large-scale CNC facility run by the company Ducret-Orges, near Lausanne. Here, he found a five-axis machine originally developed to create components to restore the region’s medieval buildings. With a working area measuring 40 meters long and 5 meters wide, the machine could fabricate not just a model of the building, or small parts of it, but full-scale structural slices. “We discovered that we could produce an enormous piece,” Roche said. Moreover, the five-axis router allowed him to realize the computer-modeled design in its full ganglionic glory. “The jump to five-axis makes it all possible,” he added. “Three-axis machines simplified the shape. Now with five-axis you get the original shape itself.”

To build the museum, which is currently in design development, Roche plans to take 1,000 locally harvested trees, turn them into plywood, and mill them into fragments 2.5 meters wide by 7 meters long. These vertical “slices,” each 90 centimeters deep, will serve as the structural system, holding mechanical services within their depth. Assembled like a loaf of bread on site, the slices will be glued together with a resin system and wooden dowels (code-required concrete is used only in the elevator core). And it’s all generated directly from Roche’s computer model, which in turn drives the milling machine.

While Roche’s vision materializes, elsewhere in Switzerland researchers are working on even bolder fabrication plans. Architects Fabio Gramazio and Matthias Kohler, both professors at the Swiss Federal Institute of Technology in Zurich (ETH), have devised what they call the world’s first flexible construction installation featuring an industrial robot. Mounted on a seven-meter-long linear track, and with a reach of three meters, the machine is designed to produce large building parts on a one-to-one scale.

The robot, a German-made KUKA model used in the automotive industry, works on an eight-axis system (including a turning table) that enables it to go beyond subtractive processes (like milling) to additive procedures, such as building up porous concrete modules or foaming polyurethane. The robot has even mastered the art of brick-laying. In a seamless process controlled by design data, the machine will grab a brick, deposit glue, lay it in a custom pattern, and change tools to glue the bricks together. The results can be seen in the robot’s first built project using digitally designed and fabricated brick walls. Collaborating with architects Bearth & Deplazes, Gramazio and Kohler designed an undulating facade for the Gantenbein Winery in the Swiss town of Fläsch. Completed in 2006, the structure serves as a climatic buffer for the facility while filtering daylight through the subtly rotated bricks.

Like proud parents, the architects see the project as a vindication of sorts for the robot’s aesthetic savvy. “Stacking bricks was our ‘proof of concept’ that the digitally fabricated aggregation of materials offers architecturally expressive potential,” Kohler said in an email. The architects, who also run an architectural practice, Gramazio & Kohler, are now developing a mobile fabrication unit, housed in a shipping container, whose software allows their industry partner to create custom brick walls for clients.

Whether robots or five-axis CNC milling, some digital pioneers caution that one-to-one scale fabrication doesn’t always add up. “Just blowing up the machines bigger and bigger doesn’t really help in terms of scaling up from a model scale to the real-world scale,” said Fabian Scheurer of the Zurich-based practice, designtoproduction, whose projects have included parametric modeling for UN Studio’s Mercedes-Benz Museum and fabrication strategies for Zaha Hadid’s Hungerburg funicular in Innsbruck. “All the machines that use homogeneous materials like 3D printers or routers,” he said, “very soon come to their limits if you try to scale up.”

Instead, Scheurer and colleagues break down structures into thousands of parts using the principles of mass customization. The Hadid project, for instance, called for double-curved glass panels held in place by 2,500 individually shaped polyethylene profiles. The engineering partner provided the geometry in the form of spline curves in a CAD model, and designtoproduction automated the segmentation of the profiles, the placement of drillings, the nesting on boards, and the generation of code for the five-axis CNC router.

The firm is now working on the new Centre Pompidou branch in Metz. Designed by Shigeru Ban and Jean de Gastines, the project features a sweeping roof made of glue-laminated timber hexagons, covered by a fiberglass and Teflon membrane. The double-curved beams are fabricated on a five-axis mill, but first, the firm had to tweak the structure’s geometry, since breaking down a structure into parts depends largely on the machines that will create those parts—their dimensions, tools, and scope of movement.

And that’s a principle architects don’t always grasp, Scheurer said: “All this top-notch modeling software out there effectively hides the complexity of the geometry. But the complexity is back as soon as you try to break it down into segments and manufacture it.”

He added, a bit ruefully, “It’s quite a challenge to find the geometry in the designs of the architect sometimes.”

Jeff Byles