UNSW Making

3D Printing: FDM

Essential tutorials and information to start working with FDM 3D printing and thermoplastics materials in the UNSW Makerspace Network

The following module will take you through the Material Extrusion 3D Printing process with plastics. You will learn about the FDM-Plastics machines available in the UNSW Makerspace Network, the Slicing Process to be able to print your 3D model, post-processing your printed parts and more!

What is FDM Printing?

What is FDM Printing?

FDM or Fused Deposition Modelling is the process of extruding a molten material through a nozzle following a defined toolpath. This process adds material layer after layer in specific places to create a tri-dimensional physical part.

3d print graphics FDM-14.png

Types of Extrusion Systems


Filament Extruders

The most commonly used and versatile type of extruder that utilises spools of thermoplastic filament that are fed into the printer.

Pellet Extruder

Plastic Pellet Extruders

Similar to the filament extruders but using thermoplastic pellets or granules that are fed into a hopper before being melted and fed into the printer.


Paste Extruders

Sometimes left in it's own category as it doesn't use thermoplastics but rather any 'paste' material that can be extruded.

Learn more about paste extruders here in our clay 3D printing learning module!

FDM Printing at UNSW

Types of FDM Printers at UNSW

Ultimaker 3/3+

More Info

Ultimaker 2+ Connect

More Info

Ultimaker s5

More Info

Prusa i3 MK3

More Info

Creality CR-10

More Info

Delta Wasp 4070

More Info


Common Filaments for FDM Printing



+ Excellent visual quality

+ Easy to print with

+ Can be post-processed easily

- Low impact strength



+ Food Safe*

+ Good strength

+ Easy to print with

+ Recyclable



+ Water soluble

- Difficult to print with



+ Very flexible

- Difficult to print accurately



+ High strength

+ Excellent wear and chemical resistance

- High fume emissions

- Absorbs Moisture



+ Good impact resistance

+ Good heat resistance

- Warps upon cooling

- Difficult to print



+ Good strength

+ Good temperature resistance

- More susceptible to warping

- Requires printer to be enclosed

Design Considerations

FDM design considerations

Considerations when Printing

Take note of some of the things that may affect your parts when printing as you may need to make adjustments to your design to incorporate these features.

Part orientation.png

Part Strength

For functional parts, it is important to consider the application and the direction of the loads. For example, FDM parts are much more likely to delaminate and fracture when placed in tension in the Z direction compared to the XY directions (up to 4-5 times difference tensile strength).

Source: 3D Hubs
elephants foot.jpg


Because FDM printing nozzles are circular, corners and edges have a radius equal to the nozzle size. This means that these features are never perfectly square.

For sharp edges and corners, the first layers of a print are especially important. With each print layer, the nozzle compresses the print material down to improve adhesion. For the initial print layer, this creates a flare often called an “elephant's foot”. Protruding outside the specified dimensions, this flare can impact the ability to assemble FDM parts.

Source: 3D Hubs
Orientation of parts.jpg

Orientation of Parts

The best way to avoid support for holes is by changing the print orientation. Removal of support in horizontal-axis holes can often be difficult, but rotating the build direction 90° eliminates the need for support. For components with multiple holes in different directions, prioritize blind holes, followed by holes with smallest to largest diameters and then the criticality of hole size.

Source: 3D Hubs

STL Files & 3D Printing

An STL is the industry standard file type for 3D printing. It uses a series of triangles to represent the surfaces of a solid model. All modern CAD software will allow you to export their native file format into STL. The 3D model is then converted into machine language (G-code) through a process called “slicing” and is ready to print.

STL 1.jpg

Guide to STL Files

STL 2.jpg

Troubleshoot Common File Errors

Preparing files for FDM Printing

What is Cura?

Cura is an open-source, free slicing software used to prepare files for 3D printing. Cura will open and read your 3D CAD drawn model (in the form of a .STL or .OBJ), slice it up into lots of layers and convert those layers to lines of code that become the instructions for the 3D printers to follow!

First step...download Cura!

Download Cura

Get Familiar with Cura

Learn to slice your models and get your design ready for printing by following along the Cura fundamentals learn page!

Cura Fundamentals
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3D Print Module Graphics-02.png

Nozzle Size, Layer Height & Print Quality

Choosing the best nozzle diameter and layer height for your model...

The nozzle diameter directly affects the extrusion diameter of each line in a 3D print and directly determines layer width or the 'wall thickness'. The most common standard nozzle sizes for most 3D printers is 0.4mm. It makes for a great all-rounder, a good middle ground between speed and quality.

A larger diameter nozzle such as 0.8mm lays down wider perimeter wall lines. This means that it uses less lines than a smaller-diameter nozzle to print a wall of the same thickness. A nozzle with a larger diameter also allows prints to have an increased layer height. A good rule of thumb is layer height should be 80% of nozzle diameter, higher than this the layers will not adhere well. Combining these two effects leads to a noticeably shorter print time of solid models when larger diameter nozzles are used.

Layer height is the height of each layer of plastic extruded when printing. This setting is adjusted in CURA and will directly influence the print's speed, resolution and surface finish.

A larger layer height means the printer doesn’t have to print as many layers to achieve the same total height, resulting in a much faster print. Generally, increasing layer height will decrease the resolution and quality of your print. This “hack” is therefore better for large prints, where close-up details will either be ignored or touched up during any post-processing.

To summarise a smaller layer height and or smaller nozzle diameter is better:

  • When part detail, resolution, and quality is a high priority
  • When surfaces must be smooth
  • When printing small, intricate parts
  • When printing parts with curved sides (to avoid visible layer lines)

Conversely, a larger layer height is better:

  • When a shorter printing time is a priority
  • When printing parts with straight sides
  • When post-processing techniques like sanding can be used to reduce the appearance of layer lines

0.4mm Nozzle

A nozzle diameter of 0.4mm is a great all-rounder for most prints and can support a range of layers heights which result in a good range of different print qualities depending on the needs of your print. Better for detailed or more complex prints where a finer resolution is required.

Recommended Layer Heights

0.06mm Layer Height

0.1mm Layer Height

0.15mm Layer Height

0.2mm Layer Height

0.8mm Nozzle

A nozzle diameter of 0.8mm is great for simple prints where speed of printing is an important factor. If you want the fastest possible print time, this is the nozzle for you!

It is great for prototyping and printing simple forms but not recommended for prints with finer details where a higher resolution is required.

Recommended Layer Heights

0.3mm Layer Height

0.4mm Layer Height

0.5mm Layer Height

0.6mm Layer Height

Other Resources

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Design Interlocking Joints for 3D Printing

snap fit joints.jpg

Design Snap Fit Joints for 3D Printing

Related Badges

Categories: Digital Fabrication