Project Title:  Buoyant Extrusion
Dates:  Spring 2012 (Initial Research), Spring 2014 (Rob|Arch Workshop)
Project Lead:  Ryan Luke Johns, Nicholas Foley, Axel Kilian

Buoyant Extrusion is a 3D printing technology that leverages material buoyancy to resist the force of gravity during printing.  By carefully calibrating the specific gravity of the extruded thermoset resin (urethane plastic or rubber) with that of a substrate liquid (i.e. sodium carbomer gel), we can “program” the material to slowly sink, rise, or remain in position.  This allows for large scale, freeform printing without the need for additional support material.  As opposed to traditional contour-printing with layered bands, this process enables ultrafast extrusion of spatial forms.  This makes efficient large-scale-printing feasible, while also opening the possibility for more interesting “materially informed” prints.  By isolating and manipulating variables of density, temperature, curing time, viscosity and the rate, path and depth of extrusion, the process allows for complex geometries to be produced with minimal effort or computational complexity.  For example, to create thicker or thinner members with traditional 3D printing, one has to model that geometry, and then slice it into layers.  With this process, thickness can be calibrated simply as a variable of speed: faster speeds make thinner bands, and slow speeds make thick bands. Similarly, a sphere (or connecting node) of a specific radius can be produced by extruding the resin in a fixed position for a given amount of time.

Selected Related Work:
US20030090034 (2000) Fluid Cast (2009) NGPS (2010)