TwistedLam: A Robotic Fabrication Method for Hyperbolic Paraboloid Glulam and Clt Blanks

Abstract

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 sawmill stage, to cut sets of doubly curved boards from a log with a 6-axis robotic arm and bandsaw end effector. The boards were laminated into two hyperbolic paraboloid prototypes: a doubly curved glulam column and a doubly curved CLT blank. Through the construction of these two prototypes, the method not only reduces the amount of discarded material but also simplifies the lamination of the process by eliminating the spring-back produced from twisting flat boards into doubly curved boards for lamination of doubly curved glulam and CLT blanks.