While attending a health and beauty trade show in the fall of 2009, Nick Starno watched as countless exhibitors struggled with cosmetic tubes, vainly attempting to squeeze the last few drops out of them. Starno, however, is a mechanical design engineer, and familiar with 3D printers. When he got home, he designed a tube squeezer and posted his prototype on a community Web site for 3D printer designs. Within hours, several 3D printer enthusiasts in Europe had downloaded his design and manufactured the tube squeezer. Since then, Starno's design has been downloaded more than 500 times and people around the world have produced his tube squeezer at a cost about 30 cents each.
"I knew that as long as I could model it on the computer, it could be made," says Starno, who now works with Makerbot, a 3D printer company. "No worrying about tooling costs, post processing, surface finishes, packaging, shipping quantities, or advertising. Anyone with a 3D printer could search for my design, download it, and make one on demand without ever leaving their house."
Printing simple devices such as tube squeezers might not seem very exciting or sexy, but it heralds the beginning of a technological revolution involving thousands of hobbyists around the world who are using 3D printers to fabricate wine glasses, toy cars, cooling fans, mechanical arms, and countless types of nuts, bolts, and gears.
To many observers, this revolution mirrors the personal computer revolution, with its kits for hobbyists, of the 1970s. "There are many parallels between personal computing and personal fabrication," says Hod Lipson, an associate professor of mechanical and aerospace engineering and computing and information science at Cornell University. "I think you can look at the history of computers and how they changed our world, and you can anticipate many aspects of 3D printing and how they will interface with every aspect of our lives."
While large-scale, commercial 3D printers have existed for years, personal 3D printers are a recent, fast-spreading phenomenon. Dozens of startup companies are developing and marketing 3D printers, but two of the most widely used 3D printers are open source projects.
Based at the University of Bath, RepRap is the brainchild of Adrian Bowyer, a senior lecturer in the department of mechanical engineering. The other project is Fab@Home, which is led by Lipson.
To design a printable object, a user needs a computer equipped with a computer-assisted design (CAD) program. The different RepRap and Fab@Home 3D printers are the size of a standard office photocopier, and feature off-the-shelf components including a chassis, tool heads, and electronics. The 3D printers work almost the same as a standard printer, but instead of using multi-colored inks, a printer's mobile arm includes a syringe that ejects melted plastic, slowly building up the "image," layer after layer, into a real object. Simple objects like a gear, for instance, can be completed in less than an hour.
The parts for the latest RepRap printer, Mendel, cost about $525, but an online network of artists and inventors are constantly modifying and improving Mendel's design. Moreover, Mendel prints about 50% of its own parts, excluding nuts and bolts, so it is almost a self-replicating machine.
"It's designed to copy itself because that's the most efficient way of getting a large number of them out there," says Bowyer, who estimates more than 4,000 RepRap printers have been made since the plans for the original RepRap Darwin printer were first released in 2008. "If you've got something that copies itself, then, in principle, the numbers can grow exponentially fast, and that's faster than any other means of production that humanity currently has."
In addition to enabling people to manufacture objects they never could before, 3D printers could lead to radically new designs that are not possible with traditional fabrication techniques. "Your first instinct when you have one of these machines is that instead of making something in the machine shop, you are just going to print it," says Lipson. "But at some point you realize you can make new things with complicated geometry that you cannot make any other way. You don't have to stick to straight edges and flat surfaces that can be easily machined or thin walls that can be injection molded. You can make absolutely any shape that you want."
For instance, Lipson's team has experimented with printing objects with both hard and soft materials. When the materials are printed at a random 50%-50% ratio, the results are ordinary. However, when the dots of hard and soft material are printed in special patterns, the material, when stretched like an elastic, actually gets thicker.
Indeed, one of Lipson's favorite 3D printer materials is Play-Doh. He recently used it to create miniature copies of the U.S. space shuttle during a school visit as part of the Fab@School project, led by himself and Glen Bull, a professor of instructional technology at the University of Virginia. The Fab@School's goal is to use 3D printers to show K12 students the combined power of math, science, and engineering. The MacArthur Foundation and Motorola have awarded $435,000 to the Fab@School group to develop curriculum, build more 3D printers, and expand the project.
Although Play-Doh and other squishy substances can be used in 3D printers, melted plastic remains the primary material. Other desirable materials, including various metals and ceramics, are more challenging to use. Progress has been made in printing with metal, but more experimentation is needed to make the process easier and overcome fundamental properties in the materials like melting point and viscosity.
For Lipson's Fab@Home project, the ultimate goal is to design a robot that can walk out of the printer. Before that can happen, "inks" for batteries, actuators, wires, transistors, and numerous other pieces must be developed. However, Lipson's lab has already developed an actuator that operates with low voltage and a printable battery.
Adrian Bowyer at the University of Bath has had success making a printable conductor that melts at a lower temperature than the plastic does. Due to the temperature difference, the 3D printer can manufacture plastic channels that do not melt when filled with the hot conductor for wires or other electrical circuitry.
"At the moment the way we manufacture goods is from economies of scale," says Bowyer. "It is more efficient to make lots of one thing in one place and that's how conventional industry works all over the world. But there are many things we used to do that way that we don't do anymore. For instance, I'm old enough to remember my parents getting personalized letterhead printed at a local printer, whereas now we have computer printers. Imagine the idea of a whole industry disappearing, and everybody making what they want in their own home. That would be a pretty profound economic change."
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