Rough Pass Extrusion Tooling. CNC post-processing of 3D-printed sub-additive concrete lattice structures

摘要

Rough Pass Extrusion Tooling advances the manufacturing precision of full-scale Sub-Additive 3D printed concrete lattices in a three-step process that involves spatial 3D printing, high precision 3D scanning, and CNC post-processing. Utilizing robotics and computation, Sub-Additive Manufacturing (Battaglia et al. 2018) leverages digital workflows to produce structurally, materially, and spatially optimized lightweight concrete building components. Instead of further refining the 3D printing practice towards accuracy, and unlike other research projects that investigate 3D printing and subsequent post-processing, the method proposes to deliberately print a “rough pass”, accommodating any fabrication inaccuracy inevitably resulting from the concrete material and nozzle extrusion process. In a second step, supported by the advancement of 3D scanning, accuracy and geometric intricacy are achieved through locally post-processing components along edges, in pockets, on surfaces, and in areas of joinery. Rough Pass Extrusion Tooling enables the incorporation of higher fabrication tolerances as well as the integration of building systems, hardware, and complex connections. The method takes full advantage of the 3D printing process while introducing means to dramatically increase fabrication precision. Procedural infidelity – not aiming to solve accuracy through 3D printing alone – enables the development of a technically, methodologically, aesthetically, and performatively progressive multi-process fabrication method which opens a new realm for concrete printing accuracy. This paper closely examines CNC post-processing for Sub-Additive concrete print assemblies, addressing methodologies, opportunities, and shortcomings of such an approach.