Outside Hollywood

Experiments in 3D Printing
Posted: November 16, 2012 at 10:52 am, by Isaac

Earlier this year I printed some 3D objects at Shapeways. 3D printing is a fairly new technology, with lots of methodologies and applications. In its simplest form, it’s just like regular inkjet printing, but instead of the print head laying down a drop of ink, it lays down a blob of plastic, and once the first layer is done, the print head starts printing plastic on top of the plastic. After several hundred layers, a 3D object is finished, and can be assembled into a UAV, or a rifle reciever, or a magazine.

Different printers can print different types of resin, plastic, ceramic, and even metal. Some printers have an ink nozzle right next to the media nozzle, so it can paint objects in full color while printing. Other dual-head printers can print a rigid plastic and soft rubber at the same time, or ABS and wax. This is useful for objects with a lot of non-touching moving parts, like gears. The gears and axles can be printed in hard plastic, supported by the printed wax until the object is done and the wax can be melted or crumbled out.

Objet Printed Gear Widget

There are even experiments in printing blood vessels and human organs, cell by cell, custom designed for transplant surgeries. As the printers get more sophisticated, they can do more things. Researchers are building machines than can print optics and electronic sensors directly into objects during printing. One of the great advantages of this system is that the cost is the same to print one object as it is to print a thousand. Mass production of injection molded plastic still might be cheaper in the long run, but there’s no setup cost to print a single custom product.

Despite a number of homebuilt printers and successful Kickstarter campaigns to develop cheaper models, it’s still a fairly expensive field to get into. That’s where Shapeways comes in. The entrepreneurs at the company have invested in several different types of printers, and allow users like me to upload our models and pay for the materials and machine time to have them printed.

Compass models

I was making jewelry. I made several different pendant designs, since the price was the same if I was printing ten individual models or ten copies of one model. Shapeways prints a variety of materials, even food grade ceramic, but I wanted to try out the metal options. The cheapest material is a nylon polymer. It’s fairly strong, flexible, and reasonably detailed. It’s a great substance for prototyping, but because it can be polished and dyed, it can also serve an a finished product.

The metal printing is similar to the plastic, with one extra step. The print head lays down a steel powder, which is held together with a glue. Once the object is finished, it is placed in an oven, and sand is packed around it. The oven melts the glue out, but the sand holds the steel dust together until it fuses to itself, and a bronze material in the sand is drawn into the tiny gaps left by the glue. Here’s how it compares to the nylon print.

Nylon and Stainless Steel prints

The final result isn’t particularly strong, since it’s a steel/bronze alloy that has been essentially cast at low temperatures. It also loses a little detail on the edges during the firing, so it’s not going to work for machine parts, but it was fine for my purposes. Shapeways technicians can also plate this object with bronze or gold.

I built the objects in Lightwave 3D, and uploaded .DAE files to Shapeways site. It actually took a few tries to get an object that was actually printable; their automated software would let me know if a model’s points were too sharp, walls too thin, or details too fine to physically duplicate, and at first all of my models had errors. As you have seen, the steel pendant’s edges are a little blurred by the limited resolution of the printer.

Mesh Detail

Another printing option is Sterling silver, which requires yet another step (and is understandably more expensive than steel). The silver process starts with a wax print that comes off of an extremely precise printer. A plaster mold is built around the wax print, and when it sets, the wax is melted out, and molten silver is poured in. When the silver cools, the plaster is broken off, and the finished cast is cleaned and polished.

This is basically the ancient “lost wax” method of casting, but today the wax model is handmade by robots. Because the wax printer is capable of building models at a much higher resolution than the metal printers, the silver objects have much greater detail. All in all, I printed nine objects, and I’m pretty happy with all of them. Some handled detail better than others, and now I have a better idea of what type of geometry works with the different materials.

Shapeways Sterling Silver Print

By the way, Shapeways is more than just a service bureau. Every object uploaded can be added to the Shapeways store, which is packed with tools, jewelry, coffee mugs, phone cases, camera mounts, insanely complicated Rubik’s cubes, detailed models of obscure dinosaurs, and more. A lot of the objects can be customized, and most are available in a variety of materials. This means that the store contains a possible 6 billion different products. It’s a great example of a disruptive company, even if the technology is still in its infancy.

As various companies are working to bring to cost down so we can all have 3D printers in our homes, other companies are bringing the technology up, so we can print machine-ready replacement parts for our cars, or complex electronics. It will be fun if this becomes a second industrial revolution, and high-end manufacturing goes back home as the giant factories close. I don’t know what’s more interesting; a return to the cottage industry model for production, or the ability for basement inventors to make literally anything they can design.

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1 Comment

  • This is amazing technology! I am a HUGE fan of enabling everyone in these sorts of ways. I really think this technology needs to get out there fast. Imagine the amazing film props you can create and reproduce quickly! Bits a pieces for costumes. It looks to me like anything you can create on the computer in a 3D program you will be able to print. and they can paint your prints at the same time? AMAZING STUFF!

    Posted by Justin Lewis on February 18th, 2013 at 10:59 am

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