ExOne’s ProMetal 3D Printing

One of my favorite types of 3D printing is the 420Stainless/bronze composite from ExOne. It’s a powder-based process that is very similar to the Z-corp (Now owned by 3D Systems) plaster printers. The processes fall under the same 3D printing patent licensed from MIT. An organic binder “glues” the powder together, and a series of carefully developed processing steps burn out the binder and replace the voids in the powder with bronze. This is an odd mix, since these metals are not very similar. You could not weld them, and this is not an alloy, but a mottled mix of about 60% steel and 40% bronze. Here is a close up of a polished ring:

The metal grains vary in size, but they look about about 25-50 microns in diameter. The crevice in the image is a layer boundary. The polishing process removes projecting roughness, but is not aggressive enough to remove depressions. The material and process produce a very nice aged, textured look. There is always a small flat spot on a model where a stem allowed bronze to flow into the part, but they are much more free of defect than raw DMLS parts, and the price is far less. Aside from the pleasing appearance, the material is resistant to oxidation and very strong (about the same as structural steel).

The metal printed Time Keeper, available customized on Shapeways

The mixed bronze gives the metal a slightly warmer hue than regular steel, and depending on some variables in the process, can come out mildly golden in color. I was curious about the composition of the metal, and measured it with an X-ray spectrometer. The elemental composition in the sample I took was:

Iron 45.00%, Copper 40.30%, Chromium 9.97%, Tin 3.58%, Cobalt 0.58%, Manganese 0.31%, Silver 0.17%, Palladium, 0.05%, Nickel 0.02%

Not much nickel, surprisingly. This mixture has a lot of chromium, but not more than typical stainless steel. The lack of nickel interesting to me partly because, apart from being a common component of stainless steel, nickel works well with copper, the main non-ferrous component in the material, so this is the opposite of what I would have guessed. ExOne has a lot of variations on their process, and can do huge parts up to a meter square, weighing hundreds of pounds. Using this material for years, I keep finding more and more good uses for it. Unfortunately this process needs huge vacuum ovens, so we won’t be doing this at home, but the number of installations is increasing, and even Shapeways has plans to purchase their own setup eventually.

UB Gymnastics intro video in production

The Purple Knights gymnastics team at the University of Bridgeport has won an incredible five consecutive championships in both national and regional titles over the last five years. Ten in five years- an amazing record! They deserve a high-quality intro video to represent them online and at meets, so I’m doing my best to put together some great content to show off their skills. We did a ton of work during the first day of production earlier this month. While I was prepared with cameras and lighting, I didn’t actually know how many people were on the team, so was a little surprised when 31 gymnasts filed into the studio.

In about five hours we did six group shots, nine solo, and three pairs. Of course it was busy, but I was amazed at our productivity considering the difficulty of coordinating so many people. The discipline and team-work they bring to their sport was equally well applied in this case. This little army can array themselves in requested configurations in a matter of moments with very little direction. What a pleasure to work with!

Senior gymnast Erin Turner, who is my motion-graphics student, is directing choreography. I managed equipment (grip) and technical requirements for the shots. We used a combination of a high-speed camera shooting at 3k (7 Megapixel) 30fps, along with an HD camera for pre-roll and post-roll on each shot, as well as a DSLR for stills. Junior gymnast Chisaki Hagata assisted with camera operation.

Junior Knights Chisaki, Sasha, and Caitlyn

Jenna and Zahra. They look so sweet, but make them laugh and it's like BOOM! Monster six-pack abs. This crew of athletes is in incredible shape.

Senior Knights. This is what is known as a "Swerve", apparently.

For the remaining action shots we are moving to a much larger (and better quality) green-screen, and doing a lot within their practice space. There’s much more to this project, and the final version is months away, but I’m happy to say this is a personal record for me for scene complexity. 31 Gymnasts in choreographed motion shots make the Morning Star look simple by comparison. Go Purple Knights!


The Most Metal Moment in 3D Printing

The Morning Star is an an incarnation of beauty and danger. It is a 3D-printed sculpture of wood and steel, built by myself in collaboration with ExOne. It weighs about 15 pounds. The sphere of points is about 7.5 inches in diameter. It was printed in four pieces, and the chain portion was printed all at once. The craftsmen at ExOne polished up the points and gave it a nice dark patina for an aged look. The handle was CNC cut from mahogany in five radial sections. The base was CNC cut from oak. Both wood sections were finished with natural oils.

The spike ball design, created in Wings3D

The raw printed parts


Attaching the printed chain

Carefully brazing the chain

Polishing the points

Applying the dark patina

Milling the handle

The completed Morning star on its display base

The Morning Star was featured in the art gallery at the Rapid 3D-printing Conference. It got a great response, and I’m proud to say it was the only piece without a “Do Not Touch” sign. In fact, I ensured there was a signing asking for interaction- this is tactile art!

Afterward, I had a concept to have this brutal piece, made of one of the strongest 3D-printed materials, interact with one of the weakest materials- uninfiltrated Zcorp prints made of gypsum powder. Without reinforcing resin, those parts are very fragile and take great care to move without damage. I created a mesh of the Skull from the Visible Human dataset, and shaded reddish brown it with ambient occlusion in Meshlab. This darkened the crevices and made the entire inside dark red. The skull is life-size and took a lot of work to empty the loose powder from the small holes.

From there, I had a plan to modify the greenhouse in my backyard into a Smash House. I credit Whit, my roommate at the time, for the creative name for this structure dedicated to smashing things with a big metal spike ball.

Welcome to the Smash House

The side of the greenhouse was cut away, the bare frame was painted firecracker red, and a platform was built on the side to mount several cameras. I bought a special camera capable of filming up to 1000 frames per second, though it was used in the 240 fps mode to maintain decent resolution. A hinged apparatus was built to support the morning star, and also to mount a first-person view camera. I had a few friends over to assist in setup and filming.

Right before the smash, I spritzed the skull with water to further reduce its strength, increase its weight, and mitigate dust from the impact. The skull was aligned just off-center so more of the face would be visible in the shot. The ball was aligned just above the lower jaw in the hope that it would remain there as the top of the skull was obliterated. It worked perfectly.


The shot could not have gone off any better. The face was pulverized, leaving the broken lower jaw almost where it stood. The skull tilted backward just as the lowest point wedged it against the ground. The point split it right down the center (along the grain direction), and the two halves of the cranium were sent flying in opposite directions. Smash.

The beautiful shots from five different cameras were assembled into a video, shown below.

Morning Star – The Most Metal Moment in 3D Printing

Thanks to ExOne and everyone else who helped me on this project, which may very well be the most Metal moment in 3D printing.

The 3D-printed Bra

Mardell models a 3D printed top with flexible elastomeric cups

3D printing is perfect for creating items perfectly fit for one person. It has already been applied successfully for prosthetic limbs, joint implantsorthopedic implants and inserts, orthotics, orthodontics, hearing aids, and many more advanced medical applications. Now that people with those rarer conditions have been helped, it’s time for 3D printing to move into applications that help the masses. 75–85% of women who wear bras are wearing the wrong size. By combining 3D scanning, custom software, and 3D printing, millions of women can live more comfortably. I am collaborating with two female industrial designers in Brooklyn who are working on just such a project, and I’m working on exploring a variety of other potential problems and solutions. Using scanning to determine size is very easy, but am taking on the much harder problem of matching and creating the desired curvature and structure. On September 21st, I showed an example design at World Maker Faire in New York that featured 3D-printed elastomeric cups. They are perfectly fit to the wearer using 3D scanning. In this case, the natural shape was ideal, and the function was only to support and preserve, with no shaping required. In cases where a sculpting of form is desired, there is an opportunity for benefit, but a fairly complicated geometry problem to achieve the perfect fit and comfort. I’m making good progress, and this project is tied in with others I’m working on, so expect to hear more about it very shortly.

3D Laser-machining of Acrylic

I have been using an Epilog laser cutter in an unconventional way lately, using it’s raster imaging mode to vaporize materials using repeated passes in an attempt to reproduce fine scale shapes from a “displacement map” image (similar to engraving, just much deeper with predictable dimensions). The most noticeable issue is that, at the 40-watt power level of the machine I am using, the acrylic material is not propelled away from the work surface in the way that high-energy lasers can do. With powerful pulse lasers, very fine cuts can be made in even metals, because the material is instantly vaporized and flies away quickly due to the expansion of the gases. This leaves very little debris at the cut, and does not allow time for the heat to propagate to nearby material, localizing the effects only to the intended area.

You can see the main problem here is that the vaporized material cannot be removed from the area quickly enough. Even with an active vapor-curtain to remove smoke, much of the material still ends up condensing back onto the surface, where it interferes with subsequent passes. There is also some non-linearity in the cut depth (the curvature of the ramp), most likely due to the short focal depth of the laser. This can be compensated for by either shifting the platform upward between passes, or by applying a lookup-table to the gradient to normalize the cutting response. There is also some waviness in the depth that appears to be from vibration in the carriage as it scans over the surface.

Here I attempted a laser-machined acrylic box that needs no assembly, only a heating stage to slump the pieces into position. Note that in addition to the miter-cut edges to join the walls, there are also channels cut in the sides to allow a top to slide into place. After the laser does its work, the acrylic  “snow” is cleaned from the piece. It is then flipped over, supported on the inside of the bottom surface, and heated until the walls swing down into position.

Flowing Forms – Experimentation in 3D Printed Wearable Tech

3D printing creates perfectly adapted forms with unlimited complexity. It follows that the ideal applications for it should play on its strengths, where using other approaches would be difficult or impossible. One of the major promises of using 3D printing for wearable designs is that is can reduce or eliminate the extensive labor required for assembly. When it comes to functional apparel that integrates wiring, fluid lines, air-flow, mechanical devices or fasteners, having everything produced at once is a huge advantage. The sections can be produced separately so the printer does not have to be the size of a person. Correctly sized, integrated fittings hold the tubes in place.

Body-conforming mesh topology derived from a 3D scan

Some experiments I have in the works are designed to integrate pathways for air/fluid or wiring, and are designed to do so without a lot of manual modeling. The path of the channel is derived from the 3D geometry of the scanned body, so the tubing lines follow the body curvature exactly. There are also some interesting aesthetic possibilities offered by these new structures, which can become part of the design rather than being tacked on top of it or covered by it. The designs are inherently organic. These first attempts look like internal organs more than something produced by a machine.

Inside surface of the tubing study

There are a lot of possibilities for building functional structures using these techniques. The most accessible and easily applied are for cooling and ventilation applications, but after some successful prototypes, the applications will be extended to channels for EL-wire or fiber optic lighting, then wiring, and finally liquids, which I anticipate to be the most challenging. Current production processes for materials that are appropriate structurally also require some access to remove support material, so some advancement in materials, processes, or both must be developed for practical transfer of liquids.

Making the Fire Gauntlet

For anyone interested in animation and computer-graphics, the Siggraph conference always brings a host of interesting research to light, and features some of the best creative work ever expressed in the digital medium. It has been interesting to see the popularity of 3D printing increase over the past few years, as animators choose to bring their designs off the screen and into the real world.

I’ve both attended and presented at the show many times, beginning in 1995 when I was just 15 years old, when I presented a 3D display system with Dimensional Media Associates. Fifteen years later, in 2010, I joined Shapeways for their first Siggraph and showed some of my 3D printed designs. Among the work I showed was one of my first experiments with customized wearable 3D printing, the Fire Gauntlet.

The Fire Gauntlet grew out of a series of sketch studies I had made studying hand anatomy and mechanics. I was also interested in exploring the idea of printing hinges and other complicated mechanical devices in one shot using laser-sintered nylon. The theme of a classically styled gauntlet is also very appealing from a display perspective. There are many examples of stories and products in our culture of a mechanical hand or glove that confers special powers or is representative of new technology, such as Nintendo’s Power Glove, the Terminator movies, the robotic hand from Army of Darkness, and several well-known DIY Steampunk-styled gloves. I saw this as a great opportunity to explore some of the technical development issues, while also making a compelling display model that would convey the massive potential of 3D printing to the attendees at Siggraph.

The design was based on a 3D scan of my hand, which was then offset by 1.5mm to allow room for a cloth lining. I built surface patches over the mesh and converted them to shells of 1mm thickness. Hinges and joint pins were added afterward with proper clearances to just barely prevent them from bonding in production. Once the excess powder was brushed away, the hinges rotate freely.

Interestingly, one of the drawbacks of using printed-in-place hinges was turned to an advantage. Since the free-play in the joint  permits off-axis movement, the surfaces being hinged together do not necessarily need perfect alignment. The result is that sections with compound curvature can be joined so that they move easily, yet as the rotation becomes more extreme, the resistance to movement increases. This is exactly what is desired, since the glove should be compliant in a rest position but not allow extreme movement that might cause injury to the wearer when encountering large forces (in a hypothetical battle for example).

The glove model was bonded to a frame to support it during production and attach it to a base. I designed a base to cut by CNC out of mahogany to match the classically styled references of the piece. The base was cut in sections and bonded together, then lightly sanded to let the tool paths show through in the final design. Those features and the natural grain were highlighted by a natural oil finish. I also added magnets, set into pockets with epoxy, to allow the piece to be disassembled easily for transport.

The gauntlet was finished in silver to highlight the curvature and brass for the hinges and frame to bring contrast to the details.

It was a really memorable week presenting at the show and hanging out with the Shapeways team. At the time, Shapeways had not yet moved to the US, so most of the team was Dutch, but they were kind enough to keep most of the dinner conversation in English.  We stayed in Beverly Hills just north of the convention center and enjoyed a week of beautiful weather. The response at the show was enthusiastic and positive, and at the time far fewer people had been exposed to 3D printing.  I did several interviews to explain what I do and what Shapeways does, emphasizing the value 3D-printing has to create unique and customized objects. My presentation skills were not as polished at the time, but I am happy to have had the opportunity to share my work in such a great venue.

Here is one of the interviews:


German TV Interview About 3D Printing

I was recently interviewed by Matthias Roeckl of the German television channel/website Puls. Puls was formerly known as On3, and is sort of a German MTV type channel, run by Bayerischer Rundfunk, a Bavarian international network similar to the BBC. Matthias took a day to come up to my studio at SASD at the University of Bridgeport in Connecticut to talk to me about the activities there.


There is also some discussion with Michael Curry of MakerBot about the “Robo Hand” project. While there is a lot about wearable prints, we also talked about some of the other issues raised by 3D printing, and how it will affect product design, manufacturing, and culture.

The Pace of Advancement in Extrusion-based 3D-Printing

There are some wild claims being made about what kind of advancements we might see in 3D-printing, particularly extrusion-based desktop printing during the next couple of years. I’d like to take a moment to examine why I think the predictions, while they might have a hint of truth in what will be accomplished, are not accurate in terms of the timeline.

Before I address the level of innovation and progress, we also have to define what constitutes innovation, and there are some slightly varying interpretations floating around. One recent view makes a very sharp distinction between innovation and invention. Invention being the point where the seed of an idea is brought into reality through experimentation or prototyping, and innovation being defined by the impact it has on us. A big example would be the iPhone, which was clearly innovative in many ways. There was not a lot of invention though, since nearly all of the components (touch-screen, mobile internet, etc.) were already available, and it was just very well designed, built and marketed, leading to incredible impact that most people agree was a great example of innovation. The definition in some peoples eyes then becomes purely defined by impact, which I don’t entirely agree with. I think the innovation was in the integration of the technologies in a conscious and harmonious way, which to me is just an example of Design that simply goes outside of the scope of what most people think of design – “how stuff looks”. The iPhone was innovative because the technologies were mature enough to perform predictably, which made it possible to create a design without glaring flaws, which is what was needed for adoption and impact. So by the ‘impact’ definition, if one of the technologies you choose is not mature enough, or some aspect of culture made it hard for people to accept your creation, or even if some random thing happened like an earthquake that prevented your product from being successful, then that means you did not contribute to innovation. It also would mean, for example, that if a factory that you contracted to produce your device simply stole it, they would get credit for the innovation. I don’t think that definition holds water. In that case both the inventor and the integrator worked together, consciously or not, to produce the innovation.

My definition of innovation is a combination of Invention and what I’m calling Integration, where the invention is gracefully married to the whole ecosystem that allows it to exist and flourish. This is essentially turning something rare and delicate into a robust commodity so that people can conceive of it, access it, and modify it, and so business people can model it, predict changes in its use, and so will be willing to help it succeed. I have put more than enough into this aspect of what I wanted to say, so for further information I suggest reading the works of Simon Wardley. Those ideas spin off into fairly dense economic theory which is not my bag, but you can get a nice intro to his ideas about cycles of innovation in this appropriately themed blog post: Spoiler alert: 3D Printing.

Is 3D-printing innovating at light speed? It may seem that way, but I think it’s been exaggerated. Let’s look at extrusion printers and quickly review their development. Scott Crump invented the whole thing in 1989. CNC machines were available, but had been limited to removing material instead of adding it. His company, Stratasys, came up with the extruder bit, and then a whole wave of other things that flowed from that, like the sparse fill, support, heated build chamber, etc. that were needed to make the output accurate and repeatable. His patent expired and along came Rep-Rap, which beget MakerBot and everyone else. Making printers a commodity is a part of “3D-printing innovation”, but in my mind we should not separate it from the invention stage because it is entirely dependent on it. Without invention there will be no innovation. How many really strong examples of invention are there in open-source extrusion printers? Ones on the level of in-fill, support, and others like Statasys added?  There were a few things with tool paths (mostly from Joris at Ultimaker), and the Thing-o-matic conveyor belt was a seriously awesome idea, but that’s about it. There are thousands of people working on them day and night, and all I see is people making them bigger or smaller or cheaper, or sticking weird materials in them. That fulfills the “adoption and diffusion” portion of innovation, but adding another extruder or changing layer thickness or whatever is not going to bring us to 3D-printed cell phones as people are predicting. There has been virtually nothing done in 20 years! Why, because people outside of industry suddenly care, will the actual technology suddenly leap forward? I’m not saying it won’t accelerate rapidly, but I want to see some examples.

I think it is more likely that new innovations will come as a result of inventions which are not 3D-printers, but create an ecosystem where the printer becomes more useful. Obvious technologies to integrate would be 3D scanning and digital object transmission. Both of those things are already here, but it is the integration of them that is innovative and has value. Both of those things need robust software (let’s call it an “information ecosystem to live in”) to reach the level of maturity needed for integration. 3D scanning software must align, clean-up, analyze and transform the data to make use of it. A digital object distribution system needs to take all kinds of situations into account and allow for economic activity to spring from it’s use. People in industry know these things, which is why we have Geomagic and Shapeways. Is it possible that one might come up with a fantastically brilliant way of doing things better while they’re tinkering with their printer? Sure! Kids who are now using one at 10 years old are going to have the perfect mindset to do exactly that when they’re 20. But it will be because they connect the existing ideas with something else, where no one saw the connection before and didn’t see how the new relationship would be beneficial. When it comes to the invention portion though, a lot of that requires some hard-core science and observation of things that haven’t already been observed for hundreds of thousands of man-hours by really smart and creative people who were working to come up with a solution because their livelihood depended on it.

If it is true that we will see the massive innovation that has been predicted within the next few years, we first need to see the inventions that completely up-end the way we think of 3D-printing. A completely new deposition method. A new way of supporting the build material that doesn’t have to be cleaned off and doesn’t harm the surface finish. We could see nearly microscopic building blocks (voxels) that link together and have different properties produced in mass quantities as proposed by Hod Lipson at Cornell. Build material might be supported by electromagnetic fields, a stream of particles, tiny robotic arms that either directly support or place temporary fixtures, or any other exotic method that will seem like science fiction right up to the moment when it becomes science fact. Since we have not seen these advancement move past the “what if?” stage, we are going to have to be patient, but more importantly, work extremely hard, to make it happen.

I understand why the change seems to be happening at a frenetic pace. There has been an explosion of media coverage, and those who have been quietly working on their own advances have suddenly been given a good reason to make a lot of noise about what they are doing and the potential it has. By the time their message filters through media, their perhaps optimistic claims can be blown wildly out of proportion. If you just heard about 3D-printing last week, and this week you read a story about printing of living cells, it is easy to get the impression that the progress had been made in one week, when in actuality the printer had been around for 20 years and the doctor had been working on that application for 10 years. Boiled down into newspaper article, then hastily reviewed in a short blog post, then summarized in a tweet, there really isn’t much reference point to give the reader. It’s just disembodied “Wow” that drifts completely out of context, and certainly does not contribute to actual advancement except where, by chance, excited investors throw so much money at it that some of it lands it the right spot.

“Well Dressed” – The 3rd Annual Fashion Law Institute Symposium

The Fashion Law Institute at Fordham is focused on a variety of issues that arise in the fashion industry.  As common as knockoff products are in the fashion industry, there is a lot of curiosity about the potential effects of new digital technologies.

On April 19th, the FLI held their 3rd symposium. There were speakers on many issues, but several panels were entirely about 3D printing. After the speakers, a reception in the atrium featured a show of 3D printed designs.

The models in the show wore Constrvct dresses with Nervous System prints, and a variety of 3D-printed jewelry and accessories.

Fortunately, the organizers of the show got in touch with me early enough to have one of my pieces re-fit and printed to match the measurements of the model, and the results were great. My Lotus Top, in black nylon, is being worn by Alona on the left. You can see many more images from around the event in This Gallery.