Plastic Utah Teapot by Steve Sady

In this test case, The iconic Utah teapot was used as a benchmark shape for research into rapid prototyping of complex 3D objects represented by NURBS solid models.

Technical Overview
The solid teapot and separate lid were created as paper-thin layers of white plastic, laid down by a Stratasys FDM (Fused Deposition Modeler) machine. This machine has been described as a computer-controlled hot-glue gun. It continuously melts a plastic cord, squeezing out a very fine trail of molten plastic that cross-hatches each layer of the solid object.

This object was made from the third-generation trimmed NURBS Utah teapot solid model created by Russ Fish, based on Martin Newell's original Utah Teapot Bézier patch model and Hank Driskill's second-generation NURBS teapot solid model. The algorithmic research explored slicing the trimmed NURBS surfaces and automatically generating the support structure of grey plastic.

When the surface of the object being created in this way slopes out away from the solid body, each layer can only extend out a small distance beyond the previous one. Wherever the surface angles out more than 45 degrees from vertical, there must already be a support structure in place to hold it up.

An ephemeral honeycomb structure is fabricated from a grey plastic, to which the white plastic will only weakly bond. After the prototyping run is completed, the grey plastic support parts are removed.

Ann Torrence
University of Utah School of Computing
Torrence (at)