What is 3D Printing and How Does it Work? by Isaac Budmen

The phrase 3D Printing has popped up in the media everywhere from Jay Leno’s garage to the cover of multiple tech magazines. Many people are curious to learn more, but given the adolescent stage of the technology there isn’t much information to be found. Here I try to address that lack of information.

Q: What is 3D Printing?

A: The process of making a three-dimensional object from a digital model.

I’ve broken this down into three main sections. In the first section I outline and explain the most popular types of 3D printing. The second section addresses the characteristics of 3D printed objects. The final section discusses current desktop 3D printer software.

Types of 3D Printing

Just like there isn’t one way to print on paper (ie. laser vs inkjet), there are multiple ways of 3D printing an object. The types of 3D printing most popularly used in the industry are Fused Deposition Modeling, Selective Laser Sintering and Stereolithography.

Fused Deposition Modeling (FDM) is the most popular type of 3D printing on the market. If we pull apart the name…

• Fused: to join or blend to form a single entity
• Deposition: to put or set down in a specific place
• Modeling: the activity of making a three-dimensional representation of a thing

… it becomes much less intimidating. FDM is a fancy way of saying it attaches layers of plastic on top of one another in order to make a thing. I typically refer to this type of printing as a “glorified hot glue gun” because it works the exact same way: The extruder pulls in plastic filament (or string) and pushes it through a very hot piece of metal which then ‘extrudes’ (or spits) it out in a specific pattern. The FDM process is also goes by the name Fused Filament Fabrication (FFF).

The other two industry popular types are called Sterolithography (SLA) and Selective Laser Sintering (SLS), and both refer to a process where a laser or other focused light source is pointed into a bath of liquid plastic or resin that when hit with the light source will harden. The machine will draw layer by layer precise images in the liquid which will harden as it goes. When it is finished, you are left with a solid model. The biggest hurdles for SLS and SLA to overcome are the objects they produce are still very brittle, in addition to the high cost of this resin and technology relative to FDM machines.

Characteristics of 3D Printed Objects

A photograph can have high-resolution or low-resolution, where high-res is a lot of pixels very densely packed together so our eyes see one smooth picture, and low-res has fewer pixels and therefore the picture looks more blocky and less smooth.

In 3D printing there are also high-resolution objects and low-resolution objects. A high-res object is one that has very very thin layers (some can be thinner then a slice of paper) so that you end up with a very smooth object where it’s tough to see each individual layer. Whereas a low-res object has fewer and thicker layers, where you end up with a rougher object where you can very visibly see each layer.

3D Printable Materials

As FDM machines are the most popular on the market, the materials those machines use are also the most popular right now. The material, called filament, is packaged much like spools of thread but are much larger and have plastic instead of cotton “string”.

Acrylonitrile Butadiene Styrene (ABS), is one of the most popular plastics. It is traditionally used to make all sorts of plastic home goods and is the material of choice for LEGO. It’s high performance in impact resistance and durability make it a versatile plastic. ABS is petroleum based and gives off a toxic fume when heated, this is not an issue with proper ventilation to the machine. ABS plastic slightly shrinks when it hardens which can cause an object to curl off of the build platform. To combat this machines incorporate a heated build platform; the equivalent of making your object on a hotplate.

The other most popular polymer is Polylactic Acid (PLA), a bio-degradable plastic made from corn. PLA is very strong and rigid; ABS is softer and more flexible. It’s a popular choice for filament because as the plastic hardens it stays very true to its original size and does not require a heated build plate.

Low Resolution [Left]  vs  High Resolution [Right]

Experiments are being done with bleeding-edge materials like nylon, wood fiber, and polycarbonates by hobbyists in an effort to expand the library of materials for 3D printers.

SLS and SLA machines do not use plastic filament. Instead, they use a liquid resin (in this case an un-hardened plastic) that, when hit with the light source, hardens into a solid.

Although still in it’s adolescence, 3D printing is quickly maturing and with it will come untold wonders.

Modeling Software

123D Design  – Part of a suite of modeling software by Autodesk aimed at beginners to 3d modeling. The whole suite is provided for free and has companion iPhone apps that allow you to make 3D models of real things with your phone’s camera.

Sketchup  – A Google-supported product, SketchUp is also popular, free and well documented.

Autodesk Inventors Fusion – Of the three programs, this is the most dense and has the highest barrier to entry. Definitely more in the advanced category, this is free software that gives more precise control of the modeling once you get the hang of the interface.

Do you think 3D printing is the wave of the future? What would you 3D print if you could?  Share in the comments below.