Best 3D Printer Extruders: Basic Buyer’s Guide

What is an extruder for 3D printers?

The extruder is the part of the 3D printer that is responsible for pushing the filament, fusing it and placing it on the build platform to build the model. A 3D printer extruder consists of many different tools that perform a combination of different tasks. Namely, there is coldend and hotend. For the purposes of this article, we will refer to the extruder as the entire element of the 3D printer that moves, melts and deposits the filament - basically the coldend and hotend. Others may refer to the extruder as simply the element that moves the filament and the hotend as the element that melts.

Coldend is responsible for moving the filament to direct it towards the head. The motor and gearbox guide the filament through the PTFE tube or directly to the head. There are two different types of cold that work slightly differently, as we'll cover in the next section. The head heats, melts and extrudes the material layer by layer through the nozzle. Two of the most important elements in the head are the heater that heats and melts the filament, and the nozzle that directs the filament during extrusion.

Types of extruders

There are two main types of extruders found on professional 3D printers: Direct and Bowden. Some types of 3D printers also have double extrusion.

Direct Extruder

In a direct extruder, the filament runs from the gear to the cold end to the hotend, all in one piece. This means that the drive and gear that moves the filament are located directly above the head and are attached to the head. Since the extruder is directly on the head, the extruder itself is heavier and slower. However, many prefer to print flexible 3D filaments with a direct extruder. Due to the direct extruder, the filament has a shorter distance to travel before it is melted and deposited, which provides fewer problems during the extrusion process.

Bowden Extruder

In the Bowden extruder, the coldend and hotend are separated by a PTFE tube through which the filament runs. Instead of placing the coldend directly on the head, the tube separates the two parts. Unlike the direct extruder, the Bowden extruder is much lighter and faster as the only moving part is the hotend. The motorized cold end is located on a fixed point in the printer. Bowden extruders produce high-quality models and are perfect for printing models with a long, continuous build. It was once said that flexible materials cannot be used with a Bowden extruder, but this is an antiquated idea. As long as there is no room for the filament to move or swing, it will be able to slide freely through the tube to the head.

Dual Extruders

In addition to the different types of extruders, some printers may also be equipped with two or more extruders. Dual extruders allow you to print multiple materials and even two models at the same time. Double extrusion allows you to speed up the printing process as there are now two tools that move around, melt and apply the filament. Twin extruders can also have an Independent Dual Extrusion System (IDEX), meaning the extruders operate independently of each other. Typical twin extruders move together at the same time, but IDEX extruders operate freely from each other, opening up opportunities for increased throughput, higher productivity and time savings.

Hotend

We cannot talk about extruders without touching the hotend. As mentioned earlier, the heads are part of the extruder that is responsible for melting and extruding the filament onto the build plate. You can adjust your hotend depending on the nozzle connected. As the filament is pushed through the nozzle, the size and type of the nozzle selected will have a big impact on the style and performance of your model. There are many different types of nozzles that you can choose and place on your 3D printers, depending on the type of material you are printing or your project.

Conclusions

The next time you look at your 3D printer, you'll feel more grateful for all the work that is done in this little device called an extruder. As with many other aspects of 3D printing, understanding this tool and how it works will help you become a more efficient user and significantly improve the quality and properties of your prints.