3D Printing

“3D printing” is itself a very general term. The media, especially mainstream marketing, portrays 3D printing to be a magical technology of the future capable of replicating complex objects. But that makes it hard to put a finger on what exactly 3D printing is, technically speaking. In reality, there are many different 3D printing technologies, but fused deposition modeling (FDM), on which this article is focused, is the most common one.

FDM prints parts using thermoplastic filament, which is basically a cord of material capable of being melted, selectively deposited, and cooled. Parts are built by adding up layers on top of each other.

This technology was created because people were wanting a way to rapidly prototype parts. Even today, rapid prototype production is one of the biggest benefits of FDM and 3D printing in general. Not surprisingly, 3D printing is also slowly becoming a potent manufacturing solution.

Before we proceed with the details of how FDM works, there’s one more thing worth mentioning. In case you already did some research on FDM, you may have noticed that some sources use the term “FFF” (fused filament fabrication), instead of FDM, when referring to the technology. Well, that’s because FDM is a term originally trademarked by Stratasys, and the other abbreviation is more of a general one. Remember, it’s the same technology, only the names are different. Today, most people (including us!) use FDM.

The easiest way to understand how FDM works is to first learn the parts of an FDM 3D printer. Before we talk about specific parts, though, it’s worth mentioning that most 3D printers can perform movements in three axes: X, Y, and Z. The X- and Y-axes are responsible for left, right, forward, and backward movements, while the Z-axis handles vertical movement.

Now, let’s look at the main components of a 3D printer:

• Build platform: The build platform is essentially the surface on which the parts are made. Build platforms are usually heated to help with the adhesion of a part, but more on that later.Extruder(s): The extruder is the component responsible for melting and gradually depositing the filament to build the model.
  • In truth, an extruder is made of two subcomponents: The hot end and the cold end. The hot end contains a heater and a nozzle which actually deposits the molten filament, while the cold end consists of a motor, drive gears, and other small components, which push the filament into the hot end to be melted.Between the hot end and the cold end lies a heatsink and fan because it’s imperative that the cold end stays cool to avoid jamming.In addition to the heatsink fan, there’s usually at least one other fan meant for cooling the molten filament after it exits the extruder – this is usually called the part cooling fan.
  Print head: The print head has one or more (one is standard) extruders on it. On the top of the print head is a tube that feeds the filament into the print head.Control interface: Some modern 3D printers have a touch screen that’s used for controlling the 3D printer. On older printers, a simple LCD display with a physical scroll and click wheel may be present instead of a touch interface. Depending on the model, an SD card slot and a USB port might also be present.

The process starts when you send a 3D model file to the printer. Once the print job is started, the nozzle starts to heat up. When the nozzle reaches the required temperature to melt the filament, the extruder pulls the filament into the hot end in preparation for deposition.

Now, the printer is ready to start 3D printing the part. The print head lowers down to the build platform and starts depositing molten filament, which cools and hardens shortly after exiting the nozzle, thanks to the part cooling fan(s). The filament is deposited one layer at a time, and after one layer is complete, the print head moves up in the Z-axis by a tiny amount, and the process is repeated until the part is complete.

Naturally, if you want to 3D print a part, you have to have a 3D model of that part. 3D models are created using 3D modeling software, usually referred to as CAD (computer-aided design) software. Here are some examples of popular 3D modeling software:

• Autodesk’s Fusion 360 (free for non-commercial use)Blender (free)ZBrush (paid but free trial)

However, most 3D printing beginners don’t have the skills required to use such software. If that’s the case, don’t worry, because there are other solutions.

For starters, there are simpler CAD software options, such as Tinkercad, a program that almost anyone can use without any prior experience. It’s an online app designed by Autodesk, one of the industry’s leading CAD software creators.

Downloading Files

With so many people gaining access to 3D printers in recent years, several sites have emerged as repositories for 3D models. Here are some of the most popular ones:

• Thingiverse (all free)MyMiniFactory (many free and some paid)Cults3D (free and paid)CGTrader (few free and most paid)PrusaPrinters (all free)

This way, anyone can get their hands on a model without any modeling skills.

3D models need to be prepared for 3D printing using a special kind of software that translates the model into machine instructions. This is done using slicing software, also referred to a slicer. 3D models are imported into a slicer, which then virtually “slices” the model into layers. The resulting files consist of G-code, which is essentially a long list of instructions followed by the 3D printer to build the model.

G-code is the “language” of 3D printers and CNC machines. These files contain important parameters required to produce a model, such as printing speed and temperature, wall thickness, infill percentage, layer height, and many others. In other words, 3D printing is impossible without G-code files!

Supports

Another of the main functions of a slicer is to generate support material. Specifically, supports are needed for parts with severe overhangs. The slicer lets you choose where to put supports and how dense you want them to be. Some slicers even offer users the ability to choose different types of support structures for easier removal or stability.

If you’re still deciding which slicing software to get, check our slicing software guide to help you choose!

A couple of things always need to be done on a 3D printer before it’s ready to print:

1. Loading filament: The extruder needs to be ready to extrude filament before printing begins. The loading process begins by heating the hot end to the filament’s molten temperature (anything above 175 °C, depending on the filament), and then loading the filament into the heated extruder.Bed leveling: In order for the printer to deposit filament and build the object successfully, the build platform must be level. Depending on the machine, leveling can be either manual or automatic. Bed leveling is very important because, if the print bed is too far away from the nozzle, the first and the most important layer won’t stick to the bed, causing the print to automatically fail.

Take a look at our bed leveling tutorial for more information on this important step!

As we’ve already mentioned, FDM 3D printers use spools of filament as the material for parts. Filament is basically a thermoplastic specifically engineered to be melted and cooled while maintaining its structural integrity.

Filaments for 3D printing usually come with two different diameter options: 1.75 mm and 3 mm (or 2.85 mm). Apart from the diameter, filaments also come in different spool sizes. A closer look at the market reveals that the most common sizes are 500 g, 750 g, 1 kg, 2 kg, and 3 kg.

One of the best things about FDM 3D printers is that they can work with a large selection of filaments. Here are just some of the different types of filament which are used in FDM 3D printing:

• Common:
  • PLAABSPETG
  Special:
  • Flexible (TPU, TPE)NylonFilled (wood, metal, etc.)Polycarbonate (PC)
  Support:
  • PVAHIPS

Filaments for FDM are also among the cheapest materials used in the 3D printing world.

Check out our filament guide to learn about the most popular 3D printing filament types. In it, we go over their uses, properties, and where you can buy them

Post-processing is the final actions you’d take to complete a 3D printed part. Here are some common post-processing steps for an FDM 3D printed part (not all are necessarily done):

• Support removal: After printing, the support material is removed. You’ll likely see some marks left on the part’s surface.Sanding: Blemishes (left from support removal or from printing) are where sanding comes in. Lightly sanding 3D printed parts can make the surface smoother.Painting: Often, you’ll be printing in a single color. So, to add more colors, details, or protection, you can paint your model!Polishing or smoothing: Epoxy coating is also one of the ways used for smoothing the surface of a printed part. Specific filaments like ABS have dedicated processes, such as vapor smoothing, for achieving a smooth surface finish.Welding or gluing: In case you want to print a large 3D model that doesn’t fit in your printer’s build volume, you can print the part in two (or more) pieces and later glue them.

Let’s discuss some of the most common issues beginners might run into when using a 3D printer.

• Warping: This occurs due to temperature differences during the fabrication process.Stringing: Thin, unwanted strands of filament across your model can be caused by incorrect tuning, temperature, or retraction settings, or even specific types of filament.Nozzle jams: A clogged nozzle is one of the most irritating problems with FDM 3D printers. If you hear a weird sound from the print head and suddenly the filament isn’t exiting the nozzle anymore, you probably have a clogged nozzle. Can be caused by poor filament quality, poor temperature regulation, or filament type, among others.Layer shifting: This can be caused by a slight wobble in the Z-axis or excessive printing speed.Under-extrusion: Under-extrusion occurs when not enough filament gets extruded during printing. You’ll know you’re experiencing this when you see ugly-looking prints with gaps between layers.Over-extrusion: Over-extrusion is when too much filament gets extruded. This results in layer drooping and bad results overall.

3D printers, like any tool, require regular maintenance to continue functioning.

• Bed cleaning: It’s always a good idea to wipe the print bed with a cotton wipe after printing. In case there are some heavier marks left or if there’s glue on the print bed, feel free to use a kitchen sponge and soap to try and get rid of it.Nozzle cleaning: Before you begin printing, give your nozzle a simple clean with the cotton pad. This ensures there’s no solid filament stuck around which may cause trouble with future prints. However, sometimes you may need to do something a bit more serious. Check out our guide for cleaning nozzles to learn more.Stray filament collection: Most printers “drool” a little to prime the extruder before starting on the first layer, but this leaves a strand of filament drifting in the build area. Pick these up and throw them out to make sure the platform is clear.

Storage mainly refers to filaments, not 3D printers. Still, it’s always a good idea to store your 3D printer if you don’t plan on using it for a while.

Storage for filaments is an important aspect of 3D printing, especially if you have several spools lying around. It’s important because if the spools are left, say, on a desk for a while, dust and moisture settle in and could potentially ruin the filament’s properties.

There are plenty of filament containers on the market, as well as vacuum bags for filaments. All these products prevent the filaments from getting dusty and filled with moisture.

Filament dryers are also a thing. These are the devices that should keep your filaments healthy or make them healthy by drawing out the moisture stuck inside. Check out our article featuring ways to safely store filament to take a closer look at the products mentioned above.