Last year, we had a crazy idea. It started out something like this: “Wouldn’t it be cool if we had a 3D printer?”
Machines for printing three-dimensional forms do, of course, exist, and utilize a variety of complementary and competing technologies known by such intimidating names as stereolithography, selective laser sintering, and fused deposition modeling. If this were ten years in the future, we would just go down to one of our local big-box stores and pick one up.
Unfortunately, solid freeform fabricators, as these machines are collectively known, are not household tools; they almost universally come with five- or six-digit price tags. They are intended for rapid prototyping, making precise models of parts that otherwise would be made by expensive and time-consuming conventional machining processes.
But we were really after a device to play with, not some uber-expensive industrial manufacturing system. So we built one ourselves.
Our idea was to use sugar as the printing medium. It’s remarkably inexpensive and is rigid despite its low melting point. As it melts, it gives off heavenly fumes — the final touch making it ideal for the home prototyper. To actually build something with it, we came up with a low-cost, low-tech method that we call Selective Hot Air Sintering And Melting (SHASAM — good acronyms help). We move a hot air gun over a bed of sugar to melt it locally. The bed is then lowered, another layer of sugar is added, and the heater is moved over the new layer, melting deeply enough to fuse to the layer below. As the process repeats, true 3D objects are produced.
We started with two junky old pen plotters that we stripped down to their useful parts: quadrature-encoded motors, belt drive systems, and sturdy mounts. To these we added an electric automotive jack (for the vertical motion of our heavy box of sugar) and a plywood frame. The tricky part of this process was designing the plywood parts — and the overall scale of the machine — to fit the found plotter parts. Past that, we added a flexible canvas liner to keep sugar from leaking out, and micro- controller-based drive electronics. Our low-velocity hot air gun “print head” was made from parts including the heating element from a soldering iron and a small aquarium pump that provides airflow. With a few late nights and a lot of luck, this crazy idea actually worked.
Since we got it working, we’ve used our new fabber to print geometric sculptures, a flexible chain of links, and a sugar bowl — made of sugar.
We’ve even decorated a cake with fabbed snowflakes. More recently, we’ve been experimenting with printing plastic and have made real progress in improving the precision of the machine.
Beyond mere refinements, we’re taking this project open source. To that end, we’ve launched the CandyFab Project at candyfab.org. Its goals are to reduce the costs associated with solid freeform fabrication, and to promote the use of fabrication technologies for culinary, educational, and artistic purposes.
The opportunities for participation are diverse: sewing, programming, gastronomy, and materials science are just a start. We are redesigning the machine to use off-the-shelf components controlled by collaboratively engineered hardware and software. Project participants are already trying out new designs and researching materials. With all this help, we plan to release plans for a new and improved model next year, so that everyone else who wants a 3D sugar printer can build one too.