3D printing has become a much more mainstream technology as printing presses are available at almost any price. Most people who need a 3D printer will probably find a model that they can afford. Regardless, 3D printing is still so new that few people know how it works.
So now is the time to answer the question “How does 3D printing work?” It is very likely that you will have to use it eventually!
Added 3D versus 3D Printing
There are two broad categories of 3D printing. Almost all 3D printers that you can buy yourself are “additive” machines. In other words, they create 3D objects by adding material (usually in layers) until the object is ready. When people hear the word “3D printer,” people think of 3D printers, which is almost always an additive variety.
Subtractive 3D printing is a different matter entirely. Here, you start with a fixed amount of material and then remove material until only the finished object remains. A sculptor sculpting a marble statue uses the subtractive method. Subtraction machines are commonly used in large workshops and industrial plants. The most famous example is CNC (Numerical Control) milling systems.
From now on, we will only focus on additive machines as they are relevant to the average consumer. Just know that subtractive machines belong to the same extended family of 3D printers as the one you can put on your desk.
Modeling of fused deposition, lithography and laser selective sintering
The three main methods of additive 3D printing are FDM (Fused Deposition Modeling), Stereolithography (SLA), and Selective Laser Sintering (SLS).
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da Vinci FDM printer
FDM is the most common consumer grade system. In these types of printers, a filament of material is passed through a hot print head. The print head is precisely positioned in three-dimensional space and applies a layer of material according to precise, programmed instructions. There are different approaches to FDM, but we’ll come back to that shortly.
Nobel SLA Printer
Stereolithography is much less common in consumer systems. These printers use lasers to turn liquid resin into hard plastic. Typically, the object is “pulled” from the resin vat, forming layer by layer as it rises out of the material. SLA printers have become more compact and affordable in recent years. So it is a real alternative to FDM printers, depending on which final model you choose.
Selective Laser Sintering (SLS) uses a powerful laser to melt polymer powder. The actual powder acts as a support structure for the printing, so this kind of printing does not need a special stage. SLS is not the type of FDM you find on the desktop. It is still an industrial technology so far.
Delta Robot Printer
Cartesian and Delta Robot Printers
The most common type of FDM printer is a Cartesian 3D printer. The name refers to Cartesian coordinates. These are the XYZ coordinates that we all learned in school. The print head can be moved to any XYZ coordinate within the print volume. The math is simple, the printers are fairly affordable, and the print quality is accurate.
However, depending on the granularity of the XYZ coordinates, curved surfaces may not be as smooth as they could, requiring some manual finishing work.
Delta’s robot printers take a different approach. The print head is attached to three arms that move along three guides. By varying the height of each arm, the print head can swing. This design allows the print head to rotate in true curves and also allows for tall objects to be printed in the print volume.
Basically, the longer the rails, the higher the model can be. Instead of XYZ coordinates, delta robot printers use trigonometry to calculate the position of the print head. The end result is that they cannot achieve the same print resolution as Cartesian printers.
To truly understand the concept of a delta robot, you need to see it in action. Watch this video by Johannes Roholl and you will quickly grasp the concept.
Pay attention to the articulation of the arms and how freely and smoothly the printhead can move.
3D Printer Materials
A variety of materials are used in 3D printers, but the two most common plastics in consumer applications are ABS and PLA.
ABS (Acrylonitrile Butadiene Styrene) is the same plastic that LEGO bricks are made of. This plastic is prone to warping when it cools and requires a heated bed printer to print. It is quite shockproof, but not particularly durable. It is suitable for prototyping parts and even non-load bearing finished parts.
PLA (polylactic acid) has a low melting point, does not warp too much, is easy to work with, and has fewer bad prints. Plus, it’s too fragile for practical use, but great for creating sleek, detailed models that you can only look at.
The good news is that most consumer 3D printers will work with both of these inexpensive materials. So you can change them as you see fit.
Nylon filament is another option, and there are even printers that use wood or metal as their material. The new generation printers can also handle more than one filament at a time, which allows printing from different materials or in multi-color printing.
3D Modeling Process
If you’ve never done 3D printing yourself, you’re probably wondering how it works from a user perspective. While using a 3D printer is not as easy as printing 2D prints with a laser or inkjet printer, it is not as difficult as you might think.
After setting up your printer according to the manual, with proper calibration and alignment, you first need a model to print.
You can create your own model using something like Zbrush or AutoCAD, but most people will likely download the model from an online site. The first stop should definitely be Thingiverse, which is arguably the most famous collection of user-submitted models. However, there are many alternatives
When you receive a model in a compatible format, you will open it in the software that came with your printer. They all look and work differently, but the basic concept is the same. You can also process the 3D model first with Meshmixer, which ensures that the 3D model is strong and printable.
In the 3D printer software, you select the size and quality of the model, and the program converts it into “slices” representing each print layer. It will also calculate the “scaffolding” that needs to be printed to support the model during manufacture. This material can be torn when the print is ready.
Now that all the preparatory work is over, you can start printing. Depending on the quality settings, you may need a long wait! High quality prints range from hours to days. Fortunately, some 3D printers allow remote monitoring of the printing process via an app.
Once the print is ready, you will remove it from the bed and then free it from the scaffolding. In many cases, you will need to sandpaper the model and use special cutting tools to remove the imperfections. Some people even color their models! The only real limit is your creativity.
If you are impatient to buy a 3D printer, this is our top choice, and if you are on a budget, these are more convenient options.