Ithaca-based studio HANNAH has installed a series of 3D printed seats across Socrates Sculpture Park in Astoria, Queens, for the summer, extending their architectural experiments in large-scale 3D printing to sectional furniture.
RRRolling Stones is the 2018 winner of Folly/Function, an annual competition held by the Architectural League of New York in partnership with the sculpture park, and will officially open to the public on July 12.
3D printing is something of a passion for HANNAH cofounders and Cornell University professors Leslie Lok and Sasa Zivkovic, and they used Folly/Function to publicize the practical side of the technology. At a full-scale printing demonstration in the sculpture park on July 11, the team discussed the technical challenges in fabricating custom seating that could stand up to wear and tear in the park, as well as the design of the massive printer itself.
The seats in RRRolling Stones were designed for maximum versatility. All of the chairs have a graphic silhouette and can be rolled to different angles to accommodate different seating styles. The chairs can also be pushed together to create a modular benching system to accommodate larger events in the park.
None of this would have been possible without the printer, a steel frame structure cobbled together for approximately $5,000 from open-source plans on the internet and assembled with help from students at the Cornell Robotic Construction Laboratory (RCL). Material is gravity-fed through a PVC hopper at the top and the nozzle uses an auger to restrict the flow of concrete. The printing arm is attached to a pulley and counterweight so that it can rapidly move up and down.
Each structure is printed in thin layers, and the mix of machine vibrations, the viscosity of the concrete, wind, the slope of the floor, and human error mean that no two pieces are the same. Printing the seats and their miniature counterparts involves much more human interaction than a ‘set and forget’ desktop 3D printer. A human needs to mix the concrete, feed it into the hopper, test the consistency, adjust the print thickness on the fly, and correct gaps and streaks in the prints before they dry. The concrete substrate is a blend of Portland cement, a plasticizer for elasticity, and nylon threads for added strength, making the final mix more of a mortar than true concrete.
The smaller printed pieces are freestanding, but the stress faced by the larger chairs meant that HANNAH had to cut and embed custom rebar structures into the full-sized seats. The seats were fabricated at Cornell, and HANNAH packed the interior of each with gravel during the printing to stabilize the chairs throughout the manufacturing process.
Lok, Zivkovic, and members of the RCL will be at Socrates Sculpture Park running a printing demonstration tonight from 5:00 to 7:00 P.M. under the park’s gantry. Afterward, visitors can take in live jazz as part of the park’s monthly series. RRRolling Stones will be on display for the rest of the summer.