Above: In the example above, students created a modular speaker set composed of interlocking triangular elements. The main materials were plywood veneer and cast plaster.

Above: After lengthy experimentation, the team utilized blue foam for the casting mold. In order to create the speaker grille (holes) the students used flexible drinking straws. The straws had a dual benefit; they were uniform in shape, creating consistent holes and were flexible enought to be removed from the setting plaster easily.

Above: A view of the assembly and components. To keep automated fabrication to a minimum, only access panels were laser cut (bottom right).

Task: For this final project exercise, students were given the constraint of working with a common and uncommon design material. The team highlighted in this example were given wood and plaster in which to design and fabricate an audio speaker set.

 

Teaching Focus: The objective of this exercise was two-fold; (1) to have students work with two contrasting design materials- one common and easily manipulated (e.g. wood) and one less common e.g plaster. (2) To cultivate hands-on material skills with the minimum of rapid, automated prototyping technologies.

 

While fabricating the wooden shell was straightforward, the main challenge was building the plaster shell. My students ran into several technical challenges; (1) creating a robust shell with adequate wall thickness, (2) how to integrated the speaker grille into the plaster form, and (3) creating a suitable mold for the plaster that could could be re-used and not damage the part when removed.

 

With regards to the first challenge, the students experimented with varying wall thicknesses that would not make the artifact look bulky and yet give the look or quality of mass that plaster affords. The students later created an visually balanced wall thickness that was robust (see upper left); thanks to the integration of wire reinforcements.

 

In order to create a series of consistent holes for the grille into the plaster cast (see photo at left), my students settled on drinking straws. They served to solve two problems; how to create a consistent array of holes and the needed flexibility to be later rmoved from the cast plaster without damaging the host material.

 

As far as the choice of mold, after some experimentation using wood, the team settled on blue foam. Unlike wood, which leaves a trademark patina of curvilinear lines, the surface of blue foam is composed of pock-marks and striations more indicative of cast plaster or concrete. The result was an honest depiction of a cast material in both bulk and appearance. An added benefit of this material combination was the quality of sound. The resulting sound had rich, deep tones.

 

 

 

 

 

 

Material Exploration: Cast Plaster Audio Speakers

 

 

© 2015 by Ken Zupan.

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