BACKGROUND

One Monday afternoon in November, we were happily led to believe we would be working on scanning an object using a 3D scanner and printing it out using the lab's fancy rapid-prototyping machines.

Without anyone fully understanding how it happened, we found ourselves split into two groups: one building a 3D scanner from scratch, and another (us) building a 3D printer from scratch.

PLANNING

We split into groups, with the full understanding that they would overlap:
1.) Chassis; 2.) Motors & movement; 3.) Extruder; 4.) Software Communication

We looked at inspirations from prior fab folks who had built 3D printers from scratch (see Links), and decided to loosely follow the Fab@Home design.

PASTA IS CHOSEN

We were still undecided about whether we should use a material that required melting, or just one that requires shearing to flow. After discussion with Kenny and Ara, we decided to test several candidate extrusion materials before deciding on one and finishing the detailed design. Food was chosen because its easy to obtain, non-toxic, and easy to clean up. A quick trip to Shaws by Stephen and Siggi resulted in hours of food fun!

Eleven food items (or combinations) were tested using syringes and nozzles in the CBA lab. Group members tried to make single lines, taller structures, and looked for stable consistency. The results are summarized below:

Testing Results

Cheese wiz: too soft, took too long to solidify
Chocolate: pretty good viscosity, melted at 90 deg C, took a while to solidify
Chocolate sauce: too saucy, didn't solidify
Marshmellow fluff: too thick and too sticky
Vanilla frosting: too soft
Gummy bears: good viscosity, but takes a while to cool and is stringy
Gummy bears & Chocolate mix: mixture separates
Marzipan: too thick
Oiled marzipan: gross, and terrible consistency
Pasta dough: good consistency, hardens pretty quickly, flows well
Peanut butter: too runny, too oily

And the winner is...PASTA DOUGH for its good structure and speedy drying properties.

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