Rapid Prototyping with Sugar
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In late 2010, I joined a mad-science/mad-art club called Site 3. Among other things, they had a MakerBot rapid-prototyping machine. While this was very cool, the MakerBot's 3D printing method limits what it can make: overhangs and certain other types of structure can't be built without quite a lot of hassle. Sintered-powder prototyping, on the other hand, lets you create arbitrary shapes suspended in powder. There's a hobbyist machine that does this called CandyFab, which uses hot air to fuse sugar. It occurred to me that Site 3's laser engraver could do exactly the same thing, probably with better resolution.


Techniques Settings Projects


Techniques

At present, multi-layer sintering is done by hand. All builds are done inside a foil baking pan (to avoid fouling the laser table). An acrylic frame one layer thick is placed in the build area, sugar is added and levelled to the top of the frame, and the layer is fused. Additional frames are added for subsequent layers, with sugar added and the laser bed's Z position adjusted with each layer. The drawback to this technique is that manual re-alignment is needed for each layer.

The eventual goal is to use a scheme similar to CandyFab's, with a sinking build tray topped off by a sugar-spreading arm between layer passes.


 Settings

Settings that worked well are as follows (fine-grained sugar):
Speed Power Notes
100 in/min 15% 1/16" thick, fine details, fuses white
30 in/min 15% 1/10" thick, decent details, fuses yellow
100 in/min 30% 1/10" thick, 1/8" details, fuses brown
30 in/min 10% 1/20" thick, fine details, fuses white

These tests were performed with a 60W CO2 laser cutter/engraver of Chinese origin. Your settings will probably differ from mine.

Common factors:

Gallery (with project links):



 Text Tests (Single-Layer)



These are single-layer tests performed with my usual engraving-mode test pattern (the letter "A").


 Companion Cube Cookies



These were intended as snacks for a Portal 2 release day party. Snack plans were hampered by the fact that the fusing process is very slow, but the project was still a partial success. The cookies were made in two layers using the 100/30% setting, with a layer separation of 1/10".


 3D Fabrication Tests



This was intended to test the resolution I could achieve with my first-attempt fabrication method, and also as a shakedown of the fabrication method itself. The most immediate problem that needs to be addressed is alignment: I'm lining up layers by hand without much guidance, and as a result they drift by 1/8" or more on each level. Registration marks on the frames may help, but I'm still approaching the limits of what I can do without more elaborate equipment.

Layers were 1/10" apart, with the laser set to 100/30%. In-layer resolution was 1/8" or better, but registration between layers was considerably worse.

Written by Christopher Thomas. Updated 17 April 2011.