research topic(s): doubly curved glulam, doubly curved CLT, hyperbolic paraboloid shell, timber shells, robotic fabrication, bandsawn robotics
material: tree logs
location: Ithaca, NY
size: 5" x 5" x 14' column + 5' x 5' x 3" CLT
principal investigator(s): Sasa Zivkovic, Director of the RCL
research team: Chi Zhang, Lauren Franco, Lawson Spencer
industry collaborators: Henkel
funding provided by: Cornell Atkinson Center for Sustainability 2020 Academic Venture Fund (AFF) grant, David M. Einhorn Center for Community Engagement at Cornell University, 2022 AIA Upjohn Research Initiative grant
additional support: Tyler Williams, the College of Architecture, Art, and Planning (AAP) at Cornell University & the Cornell AAP shop team
conference paper: { pdf }
photo of TwistedLam Column + CLT
As mass timber construction has become increasingly ubiquitous, doubly curved glued laminated timber (glulam) grid shell structures have challenged standard methods of glulam manufacturing, which rely on a wasteful process of planing dimensional lumber into thin lamellas for lamination. The resulting glulam blanks are either milled or cut into doubly curved glulam blanks, thereby discarding even more material. Instead of using dimensional lumber to manufacture doubly curved glulam and cross-laminated timber (CLT) blanks, Twistedlam is a robotic fabrication method that intervenes in the glulam and CLT manufacturing process at the raw material stage, to cut sets of doubly curved boards from a log with a bandsaw end effector on a 6-axis robotic arm. This method not only reduces the amount of discarded material but also simplifies the lamination process by eliminating the spring-back produced from twisting flat boards into doubly curved boards for the lamination of doubly curved glulam and CLT blanks. The viability and potential of this research are realized through two hyperbolic paraboloid prototypes: a doubly curved glulam column and a doubly curved CLT blank.
twisted cut board with local coordinate planes for cutting
a 6-axis robotic arm with bandsaw end-effector cutting twisted cuts
detail photo of a twisted column
drawing of column lay-up
hyperbolic paraboloid CLT w/ twisted cut boards
animation of CLT lay-up with twisted boards
animation of CLT lay-up with twisted cut boards
geometric constraints of laminating twisted boards and twisted cut boards for a hyperbolic cross-laminated timber (CLT)