What is 3D Printing?:
3D printing is the process and equipment used to take a digital file that has been rendered in 3 dimensions and producing a physical object from that digital file.
What’s so different between 3D Printers and traditional machining processes?:
3D printing is often referred to as “Additive Manufacturing”, which means that material is built up or added in layers to create an object, as in in the below gif:
Traditional machining processes have recently been dubbed “Subtractive Manufacturing” due to the fact that they start out with a solid block of material, and by using various cutters and bits remove material till the object takes final shape—as in the below YouTube video.
When did 3D Printing come out?:
In the late 1970s the theoretical groundwork was laid for 3D printing, with the first machine being developed in 1983 by an individual named Chuck Hull (here is a quick article about him, and the first 3D Printer, the SLA-1). During that time the concept and technology were referred to as “Rapid Prototyping” due to the speed in which a product could be produced as opposed to more traditional methods.
The technology stayed in the domain of manufacturing over the next 20 some years until 2009, when the first consumer machines hit to market.
What is the process for 3D printing?
After a 3D model is designed, it needs to be saved in a file format that can be read by a slicer program. The first file format, .stl (NOT to be confused with the .stl for certificate trust lists) was created by our friend Chuck Hull and stood for “Stereolithography”. While still a popular format to save 3D print as, others have popped up in the last few years such as .obj put forth by Wavefront Technologies.
After the file is saved as an .stl or .obj, the file needs to be sliced into vertical layers to be printed. The program that does this is called a “slicer” and can be thought of as a driver for your 3D printer—in very rough terms. After loading the 3D model into the slicer, the slicer cuts the model into verticle layers. Each of these layers corresponds to the layer height of the printer—for FDM printers, this is the thickness of the plastic being laid out by the printhead (.1 mm for example) that has been selected. This layer will be drawn out by the printer, and after the layer is complete, the printer will then move up a by the layer height (.1 mm again) and begin printing the next layer.
The slicer exports the sliced model as called ‘g-code’, g-code is machine language that tells the printer where to move the hot-end, how fast to extrude the plastic, what temperature things should be at—everything the printer needs to actually print. To do this, you’ll open have to have a slicer set-up for your printer. There are quite a few slicers out there and sometimes they’re packaged with the printer, and others you’ll need to get on your own. Some examples on the free side are: Cura, Slic3r, and Craftware. On the paid side is Simplify3D. Many of these programs are already set up for the most popular printers, but they are fairly easy to set-up for other printers.
What types of 3D printers are there?:
Short answer? Lots. However, most of them have very specific uses, are incredibly expensive, or both. For consumer use, there is really only two types, FDM (also called FFF) and SLA.
FDM stands for “Fused Deposited Material, which is the same thing as FFF or “Fused Filament Fabrication”. In this process, a plastic (usually) filament is heated up to around 200 degrees Celsius (392 degrees Fahrenheit) for PLA plastic or 260 degrees Celsius (500 degrees Fahrenheit) for ABS plastic* in what is called the ‘hot-end’ or “print-end’. The hot plastic is then forced through a small opening in the print-head in a process called extruding. The extruded filament is then forced on the build plate.
SLA stands for “Stereolithography”. Stereolithography uses a photo-reactive resin that is exposed to a light source which hardens the resin. For example, the Form 2 we have uses a laser tuned to a specific wavelength to do this, but there are printers that use DLP projectors instead of lasers. In the case of the Form 2, a build plate is lowered into the resin, a laser draws a layer of the object, and the build plate then moves up a slight amount (the height of the layer) and the process starts over.
What’s the practical Difference between FDM and SLA?:
FDM printers are more inexpensive. This is true for both the machines and the consumables. PLA can be had for under $30 for a kilogram (2.2 pounds). FDM machines are also easier to work on. Belts, hot-ends motors, etc can typically be accessed (though you may void the warranty) with little difficulty for the end-user. That being said, the quality of the print is limited by the fact that semi-melted plastic is being forced through a small hole. At some point, that hole can’t get any smaller— which means print detail can’t get any better. FDM printers can be compared to dot-matrix printers, perfectly usable to make text documents, but you’re not printing the family portrait out on it.
SLA printers are pricey. While the physical machines are coming down in price they’re still pretty costly. The photoreactive resin is also expensive. Form’s resin, for example, is around $150 a liter ($570 gallon). That being said the quality is far superior to the FDM printers, with the ability to go from printer to casting copies with a very minimum of work. This is your high-end color laser printer for comparison.
What else should I know about 3D Printing?:
Tons, but this is already a pretty long blog post. 3D printing is brand-spanking new in terms of technology; you’re probably going to have to put in work to get everything to work right. Even excellent FDM printers (Ultimakers, for example) need periodic adjustments and cleaning, etc. The more inexpensive the printer, the more sweat-equity you’re going to have to invest. There’s also supports that often have to be removed with varying levels of difficulty (and frustration), misprints, poorly designed models, bad filament… the list goes on.
This stuff is really, really cool. And it’s very rapidly changing the face of manufacturing. Being able to learn it and work with it has been an awesome oppritunity, and I’m glad to be able to share my knowledge with you!
*These temperature numbers are approximate and may vary by filament and printer manufacturer.