Additive rapid prototyping in plastic materials is becoming quite accessible to home and hobby users. If youâ€™re a hobbyist on a typical budget wanting to rapid prototype in metal, however, youâ€™re limited to subtractive methods, i.e. CNC machine tools like mills and lathes, and even those are not exactly â€œcheap.â€ Professional 3D printing services like Shapeways offer additive metal prototyping in metals like stainless steel and gold, but itâ€™s extremely expensive. The technology their 3D printers use, called â€œlaser sintering,â€ is fundamentally different from the RepRap-type fused-filament (â€œrobot hot glue gunâ€) 3D printers at the â€œgarageâ€ end of the pricing scale.
In selective laser sintering (SLS), the object is built up in a bed of powder by a scanning laser beam that fuses tiny bits of the powder together, one layer at a time. After each layer of the model is fused, a fresh, thin, uniform sheet of powder is swept over the bed for printing the next layer.
Swarthmore College engineering student Andreas Bastian has developed a low-cost, open-source laser sintering printer design. It uses an IR laser diode on a bed of powder made from a mixture of wax and carbon, and produces fused wax models, which can then be duplicated in metal, for instance aluminum, using a traditional lost-wax casting process. I have written before about a similar process that uses a CNC hot-wire cutter to make Styrofoam models that can then be â€œmetallizedâ€ via lost-foam casting, but that, too, is a subtractive process, and limits the possible shapes of the model in ways that the additive SLS process does not. [via Hack a Day]