How to 3D print your own Rodin
UC Berkeley, Lawrence Livermore Labs touts creating objects quicker, smoother, more complex, more elegant than other printers
For all the hype over three-dimensional printing, it’s done little to revolutionize the world of manufacturing.
An innovation out of two Bay Area labs could change that.
The new method creates near-instantaneous objects that are smoother, more complex and far more elegant than current 3D printers produce. Called Computed Axial Lithography, it was conceived by scientists at Lawrence Livermore National Laboratory and UC Berkeley.
Imagine a speedy replica of Michelangelo’s graceful Pietà, rather than a tedious version of Athens’ blocky Parthenon.
“It’s a new kind of 3D printing that creates objects all at once, rather than layer by layer. And they’re non- symmetrical, with a lot of detail,” said Hayden Taylor, assistant professor of mechanical engineering at UC Berkeley and senior author of the research paper, published in Thursday’s issue of the journal Science.
Here’s why conventional 3D printing can be a disappointment: It creates a “stair-step” effect of external lines because
layers of molten plastic are stacked one upon the other.
While cheaper than injection molding, conventional 3D printing is no match for quality. It takes time. It can’t create complex objects with different geometries. And it can’t create flexible objects that bend, because materials deform during the production.
The new tool — dubbed “the replicator” after the Star Trek device that creates objects on demand — takes a whole different approach. It has the potential to transform the design and manufacture of everyday products from prosthetics and eyeglass lenses to running shoes. And it can create flexible objects.
Scientists have already made a series of complex objects, such as a small airplane model, lattice structures, a ball inside a cage and a tiny model of Rodin’s “The Thinker” statue. They also built a model of a human’s lower jawbone, with teeth, showing that the technology could help create dental implants.
They’ve also demonstrated its other unique feature: It can encase an existing object. As an example, they added a handle to a metal screwdriver shaft.
The technology opens the door to mass customization of ordinary objects, from sports equipment to prosthetics.
“You start with a standard metal skeleton, then ‘overprint’ another geometry around it,” said Taylor.
It took two years to develop the method. The two labs have filed a joint patent on the technology.
They were inspired by medicine’s Computed Tomography, where X-rays are projected into the body from many different angles to reveal the shape of bones, blood vessels or other soft tissues.
They reversed that principal — rather than imaging an object, they created one.
An essential part of the tool is a sticky liquid that turns into a solid when exposed to a certain type of light.
Scientists project patterned rays of light onto a rotating cylinder of this photosensitive resin. The liquid solidifies into the desired shape within a few minutes.
As they increase the number of angles of light, the object increases in complexity, creating curves and smooth surfaces. The researchers demonstrated that they could shine 1,440 different projections into the resin.
There’s nothing that couldn’t also be done by an amateur hobbyist, with the right materials. The scientists used an off-theshelf video projector, which Taylor brought from home. They plugged it into a laptop to project images, while a motor turned the cylinder that held the special resin. After several minutes, the 3D structure appeared and the uncured resin was drained.
The hard part, conceived by UC Berkeley graduate student Indrasen Bhattacharya, is the computation. You need to take a 3D model of what you want to manufacture, draw it on a computer using Computer-Aided Design software and then translate that into a video image to project.
“What this approach does is make it possible for interesting polymer parts to be made much more quickly, which is often a bottleneck,” said Lawrence Livermore National Labs engineer Maxim Shusteff, in a prepared statement, “and we can now think about using materials that don’t work well with slower layer-by-layer methods.”
Not so long ago, 3D printing advocates imagined a world where conventional manufacturing would be obsolete, because people would print everything from flower vases to car carburetors from home.
But that hasn’t panned out his new technology could take 3D printing to places it could never reach before, said Taylor.
“I think this is a route to being able to mass- customize objects,” he said. “I think it may change the way products are designed.”