Digital Molds – Looking Beyond 3D Printing: Benjamin Peters at TEDxBeaconStreet (Transcript)

So let’s start by talking about 3D printing. 3D printing is a lot like normal printing, but it’s in 3D. Not that kind of 3D. But more like this 3D printing refers to additive manufacturing techniques that build objects layer by layer, starting from nothing and ending up with a completed physical object. A common exaggeration is a 3D printer is just like a Star Strek replicator, you can make anything. Although you can make very complex geometries with a wide variety of materials like plastics, powders and metals, 3D printing does have its limitations. This is why we have so many kinds of 3D printers. These are a lot of different varieties that exist, of different kinds of additive manufacturing techniques that fall within the field of 3D printing. The true magic of 3D printing isn’t it being a Star Trek replicator. It’s how we use it.

A 3D printer is used by designers to generate their parts in the real world. So, you can take a design, plug it in the printer and it’ll print it out for you. And you can take that part in your hands, make adjustments to it, change your design and print another one. So it’s used for iterative design, and it actually checks parts with the real world. So it’s a really useful tool.

A disadvantage of 3D printing is that it’s actually pretty slow. So we have a really nice little 3D printed cup over here on the left with an integrated straw. Pretty cool! That takes about the same amount of time to print or to manufacture as these plastic cups or a hundred packs of 50 plastic cups, so 5,000 plastic cups. So it’s about the same amount of manufacturing time. That’s low-balling it. So, this layer by layer additive process is pretty slow compared to a formative manufacturing technique.

So, I started to gain interest in 3D printing, when I was in my senior year at MIT. And I wanted to make a printer that was really fast and really cheap and printing with a wide variety of materials. So I was a little disappointed to find out that these goals were kind of what the entire 3D printing industry was already working on. So, I decided, I needed to take a different approach if I was going to make a big impact in this field. So, I kinda looked at the trends that exist within fabrication tools and you can plot them on this graph here where the flexibility and speed of a fabrication process are inversely proportional.

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So 3D printing on the left is very flexible, but pretty slow, and injection molding on the right, making legos is very fast, but can only make the parts the mold is designed to make. And I needed something that was both fast and flexible. Instead of our breakthrough technology that jumps out of the curve and then I found out about a little known field called reconfigurable pin tooling, probably haven’t heard of it. Essentially, the idea is to have a bed of pins that are adjustable in height and with those pins, you can generate a surface for use in molding or for other applications, this is from science fiction, this isn’t real. I was surprised to find out interesting facts though.

This is the first patent in reconfigurable pin tooling, in 1863, that’s 150 years ago. But in comparison to 3D printing, the first pattern in 3D printing was in 1984, that’s 29 years ago. So, if reconfigurable pin tooling is so cool and such an old idea, why are there no reconfigurable pin tools? While so many different 3D printers exist on the commercial shelves. Well, it turns out they are just really hard to make. So, this is a pin art toy, you’ll probably be familiar with this.

This is the most classic example of a reconfigurable pin tool. And if I were to make this electronically reconfigurable, I would have to add a motor to everyone of these pins, right? And there’s about a thousand pins in this sort of cheap desktop toy. A thousand motors is a lot of motors and that’s a really significant engineering challenge. You probably or you might have seen this video which actually came out this last week. This is a really cool example of a reconfigurable pin display, that some of my friends made at the MIT media lab.

And this device is individually actuated, so all the pins have a single motor on each one. There’s 900 pins within 3 inches resolution, and it was used for haptic interface and for making experimental services. So, if I wanted a surface that was high resolution to use as mold, why can’t I do this? Why can’t I make this surface super high resolution? Math. That’s why Math is fighting me on this one.

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When I increase the resolution, I get this quadratic scaling of the area, so length times width is area, and that’s a nonlinear term. So, when we get to high resolutions, this becomes a really big problem. We get huge numbers of pins to control, massive numbers of motors and it just becomes totally unfeasible, and everything falls apart. So faced with this hopelessness, I decided to do this for my PhD and Masters and undergraduate thesis.

And I’ve been working on it for about 3 years now. And I’ve developed a number of techniques to actuate pins and to move pins. These are some of the prototypes and I actually won an award for one of them, which is the reason I’m here, because I got picked up after that I was kinda disappointed in all of them so far. Until recently, and that’s kinda of what I wanted to talk to you about today.

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