For Shelby Cobra's 50th, designers print a working 3D replica

Shelby2This is not a real Shelby Cobra, it’s a 3D printed, working replica.

Image: Oak Ridge National Laboratory

It’s arguably one of the rarest, most coveted and often copied of all cars: The Shelby Cobra. Now it’s also one of the few to arrive as a 3D-printed and working replica.

First introduced by Carroll Shelby in 1962, The Shelby Cobra roadster is almost a mythical beast among car aficionados.

According to Hemmings.com, the first were built from British roadster chassis and powerful Ford V-8 engines. Less than 1,000 of the original Shelby Cobras were built between 1962 and 1968. Since then there are been a couple of updated models: the Completion and then a CSX8000 anniversary edition (all in very limited quantities). There have also been numerous, pricey clones and Shelby Cobra kits. The 3D version, however, is a project that could pay dividends for the rest of auto manufacturing.

Inside and out (though not under the hood, which features a specialized and energy-efficient electric motor ) the 3D-printed Cobra, which goes on display this week at the North American International Auto show in Detroit, Michigan, is virtually indistinguishable from the real thing. What’s even more remarkable is that the entire project was conceived, designed, printed and finished in just six weeks.

“Six weeks to go from, ‘Hey, let’s print a car,’ to actually having a working vehicle is unheard of. Six weeks is insane,” said Lonnie Love, Ph.D., in a video announcing the car, which was developed by the Oak Ridge National Laboratory: Manufacturing Demonstration Facility (MDF) and backed by the U.S. Department of Energy.

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The 3D printed car serves a dual purpose: It celebrates the 50th anniversary, more or less, since the Cobra was first introduced in 1962. It also highlights new and potentially cheaper and more efficient auto manufacturing techniques. In fact, the roadster took center stage when President Barack Obama and Vice President Joe Biden visited a manufacturing plant in Clinton, Tennessee, on Jan. 9 and announced a new half-billion-dollar advanced manufacturing project.

Among the companies and establishments that will participate in the innovation project is Oak Ridge National Laboratories’ manufacturing lab. Love explains in the video that while mass production of 3D-printed cars are not in the offing, everything they learn from the Shelby Cobra project could be applied broadly to existing manufacturing techniques, especially at the prototype stage where, according to Love, auto manufacturers still use giant clay models.

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Part of the 3D printed Shelby Cobra prior to finishing.

Image: Oak Ridge National Laboratory

3D printing concept cars like the Shelby Cobra will allow companies to quickly test design reactions as well as form, fit and function.

As for the car, it was printed with a BAAM (Big Area Additive Manufacturing) machine and, though the printed project came out looking rough, Oak Ridge National Labs sent the body panels to a company called True Design, which worked on smoothing it and developing specialized materials and finishes. The result is a 3D-printed car that looks as if it came off the traditional assembly line.

The Cobra won’t be the only 3D-printed car at the event. Local Motor’s Strati, which holds the title of the world’s first working 3D-printed car, will also be on display at the North American International Car Show. It too was printed by Oak Ridge Labs but lacks the Cobra’s slick paint job.

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Fully 3D Printed Working Engine Runs Completely on Hot and Cold Water — and You Can Print …

stirling13D printing is fascinating, especially to those individuals who have not ever seen the technology in action previously. However, like with all new technology, this fascination subsides as time goes on and the technology becomes more commonplace. Perhaps we aren’t quite at this point yet with 3D printing, but the intrigue generated through the seeing, touching, and feeling of 3D printed objects will surely wither with time. One man in New Zealand, named Don Clucas, realizes this, and with the help of the University of Canterbury, he has come up with a way to fascinate even those already acclimated to 3D printing technology.

In a project that could be considered “breathtaking,” “innovative,” and “potentially revolutionary,” Clucas has created what he believes is the first ever fully 3D printed working engine.  Better yet, it runs on thermodynamics, meaning all it requires for fuel is simple tap water.

“What I’m doing is creating projects for people to print, rather than objects,” explained Clucas to 3DPrint.com. “A few years ago, 3D printing was new [and] people were wowed by items that could be made. Now with wide distribution of low cost machines it has become less spectacular. I have observed the attention span of visitors to our 3D lab, looking at printed parts. [Viewing of] static objects are generally several to tens of seconds. Watching the printer running can be up to a minute, but watching and explaining these engines can be minutes. People like seeing dynamic things.”

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These Stirling cycle engines are certainly dynamic, and without a doubt have the ability to keep anyone’s attention for more than a few seconds. For those unfamiliar with how Stirling cycle engines operate, they run off of heated and cooled air or other gases. The heated and then cooled gases cause a pressure change, which in turn push and pull on the engine’s piston. To run these engines, all it takes is a bowl of hot water underneath, some ice water on top, and a small flick of the flywheel to get it started. Once complete, the engine will begin running using the hot and cold water as a way to control the air pressure.

stirling3Clucas has created all of the design files and has made them available on his website, along with instructions on assembling these engines.

“There are many things that you can do with these engines,” explained Clucas. “You can use them for yourself, or they can be used as educational instruments. For example, at a high school you could make the machines, and demonstrate them to the students to show them basic thermodynamics. If you got them in universities, you can have labs set up so that the students can actually run them, do tests on them, do examinations, and do development and optimization of the machines.”

The way in which these engines are designed means that the variables in how the engine operates can be modified. Many different setups can be created, as well as different methods of operation. The stroke of the engines may be changed, as can the phase angle of the pistons, allowing for complete customization.

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Some of the great benefits of these 3D printed thermodynamic engines are that they run clean, are completely environmentally friendly, run on hot and cold water, and run almost completely silent. Best of all, the files are completely free to download, and just about anyone with access to a 3D printer can create one.

As for Clucas, he isn’t stopping here. He is constantly working to bring new 3D printable projects to those interested in this technology. “I want to develop projects for people with a printer and little or no access to a tool shop or special technical abilities,” he tells us. “There are many published projects that are great but require special extra bits, machined parts or electronics. These projects are particularly suited to education.”

Could this lead to innovation among engine design? If just about anyone can now 3D print their own working engines, this means greater access and ability to experiment with the engineering and mechanics of this technology. What do you think? Have you printed your own Stirling cycle engine? Discuss in the 3D Printed Stirling Engine forum thread on 3DPB.com. Check out the video below, showing Clucas explaining these engines more in depth.

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