What’s Next For 3-D Printing? Car Bodies

Canadian start-up Urbee takes 2500 hours to print a car body that has only 40 parts

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Steven Cherry: Hi, this is Steven Cherry for IEEE Spectrum’s “Techwise Conversations.”

Three-D printing is stepping out of the basements of hobbyists and onto the factory floor. And the changes it will usher in will make the plastics revolution seem like a blip in the timeline of manufacturing technologies. To take just one example of something that isn’t so practical even today, consider how you would add rigidity to specific sections of an object—say, a car fender.

Here’s what Wired magazine had to say about it, in an article about the Urbee, a car whose fender and the rest of the car body is almost entirely manufactured with advanced 3-D printing techniques: “When applied to the right spots, this makes for a fender that’s as resilient as the one on your Prius, but much lighter. That translates to less weight to push, and a lighter car means more miles per gallon.”

Urbee is a new car company based in Winnipeg, in Manitoba, Canada. Its mission statement is basically, “How do we get a person from point A to point B with the least amount of energy possible?” Three-D construction is just a means to that end, along with a sci-fi-looking aerodynamic shape and a hybrid engine.

My guest today is the company’s cofounder, Jim Kor. He’s the owner of Kor Ecologic, which designed the Urbee and an upcoming Urbee 2 model. He joins us by phone.

Jim, welcome to the podcast.

Jim Kor: Yeah. Thanks, Steve. Thanks for having me. I’m really excited to talk about the car.

Steven Cherry: The popular press is starting to write a lot about 3-D printing, but I think it’s slow to realize, though, the wide range of materials you can use. We had a show last year about a titanium jawbone that was custom 3-D printed for implantation. Tell us about the plastic substance you use.

Jim Kor: Well, the substance we used on the first car, which was just the body, was just simple ABS plastic. But you’re right about 3-D printing. Because of the car, I actually, along with some group members, went to quite a few 3-D printing shows, and that is where I was kind of blown away by what is possible with these different processes. And so we just used for the first car simple ABS, but what is possible nowadays, what I keep reading about, is all the metals. Some of the biological materials like living cells can be 3-D printed, and a lot of variations of plastics, of course. 

Steven Cherry: Yeah. In the Urbee 2, you’re thinking of using a mesh of two different substances. I guess the Stratasys printer you’re using has two different print heads, so that’s not a problem. But what’s the benefit?

Jim Kor: Well, we’re just at the early stages of that, but I got involved with 3-D printing kind of on a funny philosophical level. I was just intrigued by bird bones and how strong they are and how light they are, and started looking at bird bones and saw that they weren’t symmetrical, that they’re very complicated. And I started to think that they probably follow some pattern of forces like over an evolutionary type of way. In other words, there’s no bit of bone there that shouldn’t be there. And I knew that 3-D printing, which at that time I called “graphic prototyping,” was sort of the only way that could make a bird bone, and that’s why we approached Stratasys and RedEye on Demand.

Steven Cherry: So when did you make the decision to use the 3-D printing not just for rapid prototyping but for the actual production of the car?

Jim Kor: Well, we had been going to these 3-D printing shows, and after we finished the first car, we actually weren’t sure we were going to attempt a second one. But even before we decided to attempt it, I thought for sure we would try designing for these 3-D printing machines, and the visionary at the RedEye on Demand Stratasys is Jeff Hanson.

Jeff Hanson had always sort of talked to me about the factory of the future, which is sort of a room full of these 3-D printers making production parts. And I saw real advantages to designing just for these machines. In other words, imagine designing parts that you could not make any other way—that they must be manufactured on these machines. And that started to open up all kinds of doors. In some respects, from a designer’s point of view, it was incredibly liberating, because many manufacturing processes do limit what you’re able to do, and that’s what I felt. So I started to feel like it would be a good move to attempt it.

Steven Cherry: Yeah. I want to get to that liberation in a moment, but it takes 2500 hours for all the components on the 3-D printer to print out. That’s 104 days. What if this thing actually catches on?

Jim Kor: [laughs] Well, at these early stages, certainly you can criticize that it is dis-economic, but I remember when the first Nikon digital cameras came in, and they didn’t seem very—I’m talking the very first ones—and they didn’t seem economic either. And now look at digital cameras. It’s eliminated film almost totally.

So I think having gone to these shows, I started to pick up on what I saw as the trend, and the trend seems to be, the more you start using these machines, the more economic it will start to become. And so I’m not really turned off by the 2500 hours right off the bat the first time we’re doing it, and I see that coming down in cost and time. So if that happens, I think it absolutely could change the face of manufacturing like the way digital photography has changed the face of photography.  

Steven Cherry: Yeah. So let’s talk about how liberating 3-D printing is. I gather you first designed the vehicle in a CAD experiment that only cared about reducing drag with no preconceived ideas of what a car should look like.

Jim Kor: That’s correct, yeah.

Steven Cherry: Does that mean that every car on the road today is wrong?

Jim Kor: [laughs] Well, who am I to say that? But one thing I can tell you with a project like this is when—which one of the team members Jack Slivinski pointed out to me—he said, “When you work on a project like this long enough, it sort of becomes your normal.” You start thinking of the Urbee car as normal and then, of course, all other cars look a bit abnormal.

So, yeah, we do say, or I saw in some of these presentations, that one day all cars will look like Urbee, and I tend to think that because it honors the physics of the problem. And the physics of the problem is that we move around at about 0 to 70 miles an hour under an ocean of air. That’s what we’re doing, and that demands a certain physical shape if you want to use the least amount of energy. 

Steven Cherry: So after the original design, you had a couple of industrial designers come in and make it beautiful, and the result, sure enough, doesn’t look like a car. Maybe you should just describe the Urbee for our listeners.

Jim Kor: Sure. The two industrial designers who worked on it were Terry Halajko and Dave Bernhardt, and they were fantastic, from the point of view that there were two of us that pretty well knew the aerodynamics very well—that’s Jack Slivinski and myself—and we kept relaying to them what the car needed to be aerodynamic, and they kept relaying it back to us that if it was just a land-speed-record car with no lines for your eye to follow, then it would be sort of incredibly ugly.

So we kind of kept mentioning to them that you can kind of have lines as long as they don’t cause any increase in drag. And so the body was actually sculpted by them in clay, the way you would make a traditional car, and that took several months. Then that was scanned into the computer, then the aerodynamics by Tebis in Detroit, the aerodynamics simulation was done by CD-adapco in Detroit as well, and that’s when we really knew that there were no shapes or lines in there that we were aware of that would reduce the drag further. So that’s when we thought we had the right shape. 

Steven Cherry: So it has only three wheels. In some U.S. states, that makes it a motorcycle?

Jim Kor: Yes, in many U.S. states that makes it a motorcycle if it weighs, I believe it’s under 1200 pounds. But it only has three wheels, because we don’t need the fourth wheel. It’s just added weight. And the unique part of this chassis, rolling chassis, is we made it rear-wheel steering. So we have rather large-diameter narrow tires, and the two people sit side by side, and the front two wheels don’t steer. So when they poke through the bottom of the body, there’s just slots there that the wheels poke through.

And we made it rear-wheel steering because the rear wheel just pokes through a slot in a giant disc, and the disc is what is spinning. So in other words, we don’t have giant gaps in the bottom because of turning wheels, steering wheels, I should say. And when you get to these incredibly low drag coefficients, this one is a CD of 0.15, but then most of the drag starts to be where the wheels are poking through the body, so you have to pay particular attention to that area.

Steven Cherry: Maybe you should just describe the actual shape—what it looks like a little bit compared to a regular car.

Jim Kor: Yeah, so I’ve always been interested in cars, so a lot of this project has been trying to cleanse yourself of this visual, you know, this image that you have of the automobile, which is a very emotional object. And so if you just consider aerodynamics, what you need is a very blunt, rounded nose to enter the air, and then you need to reach your sort of maximum cross section, and that’s where the two people sitting have their shoulders. That’s about the maximum width of the car.

And then from there, you have to start tapering back, to recombine all that air again that you punched a hole in traveling forward. So the magic angle is about 15 degrees. If you angle back more than that, you get separation of the air from the body. So it’s 15 degrees in side view, like the sides taper in 15 degrees, and the top and bottom taper in 15 degrees, and they reach a point at the very back of the car—all those shapes reach a point.

So that’s the shape you’re looking for: an elongated teardrop shape flattened somewhat, because it’s closer to the ground. And then Professor Kamm, I believe it was in the ’30s, came up with the Kamm tail, where if you cut off the tail very sharply at just the right cross section, you fool the air into creating this tail with very minimal penalty on the aerodynamic drag. So we do that. We give it the Kamm tail with very sharp edges in the back, and that’s about it. You round all the corners because there’s a bit of sharing done between the top, the sides, and the bottom of the air, and that’s about it. Just make sure you don’t have too many mirrors or things sticking out, because they will cause you more drag than the body itself.

Steven Cherry: Tell us about the hybrid engine.

Jim Kor: Well, the power train in the car is a hybrid, but every choice we made was to make the energy the least possible. So we were reluctant to call it an electric car or a hybrid car even, because that describes the technology more than your aim of trying to reduce energy.

To reduce energy, we felt that a car should be pure electric from about 0 to 40 miles an hour, because that handles a lot of stopping and starting, and the electric motor is very good at that. But on the highway, on highway cruising, typically you cruise between 60 and 70 miles, and the internal combustion engine is our best choice for that. And then we need some liquid fuel because we think the battery just isn’t there to go those long distances.

And then we use that internal combustion engine as an emergency to charge the batteries, but it’s actually the least-efficient possible way of converting liquid fuel into electrical energy. And then driving the car, it’s very inefficient, so you use that just in emergencies. But it’s extremely efficient to use battery power that you charged, let’s say from a solar garage or from a wall plug, and use that for driving around the city. And it’s extremely efficient to use liquid fuel to cruise at 60 to 70 miles an hour using an internal combustion engine powered directly to the wheels. So that’s what our powertrain consists of.

Steven Cherry: And you’re careful to use the phrase “liquid fuel” instead of “gasoline.”

Jim Kor: Yes, and the holy grail, in my opinion, of liquid fuel, to some extent, is ethanol, pure ethanol, and, you know, Henry Ford was planning to make the Model T run on the “farmer’s fuel,” he called it. But I’m also very conscious that we can’t switch completely to ethanol with our existing cars because that would take away enormous amount of food supply. So the ethanol that you use has to be very little, because it does impact, of course, the food chain.

Steven Cherry: It’s sort of a specialty car right now. It’s smaller than a Smart Car. It’s about three times as expensive as one. It carries only two passengers. What’s the range?

Jim Kor: The range is about 30 miles on lead acid batteries, and we might make the shift to higher-tech batteries, but we got our batteries from Surrette in Halifax, and they actually custom designed the lead acid chemistry—not the chemistry but the actual batteries.

So you can do a lot that way. If you study forklifts, you can really fine-tune the batteries for the exact application. And with lead acid, the range is about 30 miles on pure electric. And, of course, with liquid fuel, we plan a fuel tank of about 10 gallons, so the range is enormous, actually, because the mileage at highway cruising is in that 250 to 290-miles-per-gallon range. 

Steven Cherry: So you could easily take this car from coast to coast on one tank of gas.

Jim Kor: Yes, and that’s kind of—you know, our goal with the second Urbee 2 is to go from San Francisco to New York with two people and a dog, do that, at least on our preliminary calculations. And our goal—let me say it that way—is to just use 10 U.S. gallons of liquid fuel, and ideally we’d like that to be pure ethanol. 

Steven Cherry: Well, if you need a passenger for that ride, I’d be happy to join you.

Jim Kor: [laughs]

Steven Cherry: You mentioned the weight of 1200 pounds. That’s just about one-sixth of a Chevy Tahoe, which, by the way, the industry calls a midsize car. What happens when the two vehicles get into a collision?

Jim Kor: Well, what happens is physics takes over, and there is a real science to making a car crashworthy. And the science we’re following to a large extent—we call it “race car safety”—so we hope to pass the Le Mans safety tech inspection—in other words, make it as safe as any car at Le Mans. And we hope to do that for the sake of you could survive a crash with a Tahoe.

Steven Cherry: So, it has a roll cage, I guess the way a NASCAR car would. But does it also have airbags?

Jim Kor: No, it will not have airbags. And racing cars don’t have airbags. 

Steven Cherry: Wow. 

Jim Kor: [laughs] And, of course, if it needs to be registered as a car, in some states then it would legally require airbags, and then it would require all the millions of dollars required for testing of airbags. But no NASCAR and Le Mans and Formula One dragsters use airbags.

Steven Cherry: So that motorcycle designation would actually serve you well there.

Jim Kor: It serves us well, but I was always reluctant to hide behind it, if you will, because we are trying to make this car—accidents are a fact of life. Highway deaths are just a fact of life. The toll is still incredibly bad, actually, when you consider the loss of life. And we realize the danger of being in any car, and especially a small car, when you’re surrounded by semi trailers and buses and SUVs. 

Steven Cherry: There was an X Prize car competition a few years ago where Urbee came in 30th—that’s pretty far from win, place, or show—but you’ve said it was a big achievement and a big step in the car’s development.

Jim Kor: It was. You know, we had a wooden mock-up when X Prize came along. We put the wooden mock-up in the Park Theatre, which is a theater, we invited about 200 friends of the project, people we knew, and we asked them should we enter X Prize, which for a small group like us costs US $10 000 and was quite a commitment.

And our friends kind of unanimously said, “You should do it.” And I think X Prize, for us, has been the most positive experience that you could imagine. They taught us how to attract sponsors, and we’ve attracted some of the best people and companies in the world, I think, to this project. They taught us how to deal with the media. You know, we’re a bunch of introverts that never talk to anybody [laughs], so that was new, to convey what we were doing.

Steven Cherry: So where are we at with the Urbee right now? If I wanted to buy one, I can order one. And do I have to wait 104 days? And when will the Urbee 2 be coming out?

Jim Kor: [laughs] Well, where we’re at today is we’re not in production of these cars, but we are starting the second car, which we call Urbee 2. And we hope in a couple of years to drive that car, which will look and feel like a production-ready car. In other words, it will look like the Honda or the Toyota that you have parked in the parking lot. It will feel like that.

And we hope to drive it from San Francisco to New York and to demonstrate what this car can do. We hope to attract Guinness World Record and hopefully achieve a Guinness record. Because we chose the San Francisco to New York trip as a test bed, we want to prove that we can do that trip in, I believe 50 hours is the Google time. So we’re not going really slow. If you go really slow, you can increase the mileage tremendously, but we want to mix with traffic. We want to do this trip on around 10 gallons of gas. And then we think there might be quite a bit of interest in this kind of car, which is just a two-passenger car and a dog. It’s not the car for everybody, but it could handle an enormous amount of trips that people do, so…

Steven Cherry: I think it will attract a lot of attention, and it will be well deserved. Compared to the Urbee, most new-car designs just tinker around the edges, and I think it’s very exciting when someone starts out with a tabula rasa. Thanks for doing that, and thanks for joining us today.

Jim Kor: No, thank you very much. I appreciate the opportunity to talk about the car. Any time, Steve.

Steven Cherry: We’ve been speaking with Jim Kor, cofounder of automotive start-up Urbee, about 3-D printing a car that’s lighter than ever seemed possible.

For IEEE Spectrum’s “Techwise Conversations,” I’m Steven Cherry.

This interview was recorded Tuesday, 19 March 2013.
Segment producer: Barbara Finkelstein; audio engineer: Francesco Ferorelli
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