The Plaster Disaster

Plaster Disaster printing with caulk.

The Challenge: Construct a 3D printer in as monolithic a fashion as possible using plaster as the primary structural material.

Technical Approach: We began by casting a leadscrew driven single-axis motion stage as a test of several techniques that we developed: insert casting of motion components such as bushings and leadscrew nuts, the use of laser-cut acrylic as a mold, and insert casting of threaded inserts. This experience informed our design of a full 3 axis 3D printer, which we cast in two pieces. The first was a four-legged base with an integrated Z axis, and the second was an XY stage in the spirit of the Foamcore CNC project. The plaster XY assembly was later replaced with an acrylic version as machine development progressed beyond the self-imposed material constraints.

Selected Design Features: High-resolution stepper motors and micro-stepping drivers are used to achieve approximately 0.001" resolution in the X and Y directions. Because both motors remain stationary, thereby reducing the mass of the toolhead, high speeds and accelerations are possible. The Z axis is driven by a leadscrew mechanism easily capable of lifting the table and build surface.

Our initial process test involved casting a single-axis motion stage. Kwang is shown pouring plaster into the two-cavity mold.
The cast-in-place bushings provided smooth movement to the stage. Our plaster XY stage used capstans for stabilization and timing belts for motion transmission.
At least one roll of tape died sealing the mold for our monolithic base. The plaster disaster was reviewed at the class's culminating exhibition.
We shipped the Plaster Disaster to California for Maker Faire 2009. It arrived Humpty Dumpty style. The Plaster Disaster can print any material which can be extruded from a syringe.