Infill can look great, add strength, and save money, but everything depends on the specific print. Find the best infill patterns in Cura for your application.

3D printing is often used to produce parts that could just as well be manufactured using another production technique. Although the final results may look the same, what matters is what is inside.

One of the main advantages of 3D printing is the ability to change the internal cavities of a part. From a manufacturing perspective, a hollow part requires less time and material than a solid one, reducing overall weight and costs!

The inside of a 3D print is called infill and can be adjusted according to density – 0% means a hollow object, while 100% is solid. The way the part is filled can also be adjusted using a wide range of patterns, each with its own unique benefits and strengths.

In this article, we will look at different infill patterns, specifically those available in Cura. Let’s get started!

What infill patterns are available?

Infill patterns can have a major impact on the strength and ibility of a print.

The latest version of Cura (5.6) offers 14 types of infill patterns. We have divided them according to what they are best suited for:

• Models and figurines: Lightning, lines, zig-zag
• “Standard” 3D prints: Grid, triangles, tri-hexagon
• Functional 3D prints: Cubic, cubic subdivision, octet, quarter cubic, gyroid
• Flexible 3D prints: Concentric, cross, cross 3D

Since Cura version 5.5, it has also been possible to generate custom tiled infill patterns, including Honeycomb, but more on that later. For now, we will focus on the standard infill patterns available in Cura.

Models and figurines

Ship models and figurines are ideal candidates for low-strength infill.

Typical infill density: 0-15 %

When used as models or figurines, 3D prints usually do not require much strength. This is because they are not subjected to heavy handling or stress. Some prototypes are also good candidates if they are not tested for strength.

For such applications, the best infill patterns are Lightning, Lines, or Zig-zag, as they provide the fastest prints.

Lines (left), lines with the “Connect Infill Lines” option selected (center), and zig-zag (right) (Source: All3DP).

Lines: Similar to the “rectilinear” pattern in other slicers, this is a 2D grid of disconnected lines, with only one axis printed in each layer.

Zig-zag: Essentially the same as Lines infill when the “Connect Infill Lines” option is selected. In other words, it is one continuous line per layer, oriented in one direction.

Lightning: An internal support structure resembling lightning bolts that becomes denser toward the top of the model. Because it can reduce material consumption by up to 90%, this infill pattern is excellent for fast prints.

Standard 3D prints

These upgrades for the Anet A8 printer may require a medium level of strength (Source: papinist via Thingiverse).

Typical infill density: 15-50%

For 3D prints exposed to low stress, such as the filament guide shown above, medium-strength infill should be used. Infill patterns such as grid, triangles, or tri-hexagon are also suitable. Keep in mind, however, that these patterns can increase print time by up to 25% compared to Lines.

• Grid: A self-explanatory 2D pattern, the main advantage of grid is printing speed, as it is the simplest of these three patterns.

• Triangles: A 2D grid made up of triangles, this pattern has an inherent strength advantage when a load is applied perpendicular to the object’s front surface. It also makes sense for parts with thin, rectangular components that might otherwise have very few connections between the walls.

Triangles (left) and tri-hexagons (right) infill patterns at 20% infill density (Source: All3DP)

• Tri-hexagon: This 2D pattern creates hexagons interspersed with triangles. One advantage is that hexagons are an efficient shape, making it a strong infill pattern relative to the amount of material used. In addition, tri-hexagon infill has shorter lines connecting each side, resulting in fewer sagging issues due to poor print cooling.

Functional 3D prints

Some 3D prints are simply designed to bear a load (Source: Jaenne via Cults).

Typical infill density: >50%

Functional 3D prints, such as the shelf bracket shown above, require high strength in multiple directions. Strong candidates for infill patterns include cubic, cubic subdivision, quarter cubic, octet, and gyroid.

• Cubic: This pattern is a 3D grid consisting of inclined, stacked cubes.

• Cubic subdivision: This variant of cubic uses less material.

• Octet: Also known as tetrahedral infill, this pattern arranges pyramidal shapes.

Cubic (left) and octet (right) infill patterns at 50% infill density (Source: All3DP)

• Quarter cubic: This 3D pattern is similar to octet, but half of the pyramidal shapes are offset relative to the other half.

• Gyroid: A particularly unique 3D pattern that creates the impression of waves. The result is a print that is equally strong in multiple directions. This infill pattern is therefore an excellent choice for a part that will be exposed to loads in multiple directions.

Quarter cubic (left) and gyroid (right) infill patterns at 50% infill density (Source: All3DP)

The patterns above are often also used at lower infill densities because of their aesthetic appearance. Some makers like this type of effect, as shown by this vase with a gyroid pattern.

Flexible 3D prints

Some infill patterns are more ible than others (Source: Creative Tools via Flickr).

Typical infill density: 0-100 % (depending on how “bendable” you want your print to be)

For ible filaments, it is best to use ible infill patterns that preserve the print’s ible nature. Infill patterns such as concentric, cross and cross 3D are best suited to this type of print.

• Concentric: This 2D pattern creates “waves” inside the print that mimic the shapes of the outer walls. It resembles a stone thrown into water, creating concentric circular ripples on the surface

Concentric (left) and cross (right) infill patterns at 25% infill density (Source: All3DP)

• Cross: Another 2D pattern, cross, creates grids that look like highly ornate crosses. Gaps form between the crosses, allowing bending and twisting.

• Cross 3D: This 3D pattern is similar to the cross pattern, but as the print rises, the lines move at an angle. The result is an object with slightly greater rigidity.

Tips and tricks

The infill direction is usually set to 45 degrees (Source: Benjamin Goldschmidt via All3DP)

Choosing an infill pattern is important, but it is not everything. Here are a few things to consider the next time you set your print parameters in Cura.

Infill line direction

One frequently overlooked infill setting is the infill line direction. The default value is set to 45° so that both the X and Y motors work simultaneously and print infill at maximum speed. However, it may be beneficial to orient the infill at a different angle to ensure maximum part strength or ibility, especially if its walls are aligned diagonally.

Gradient Infill vs. Gradual Infill

When we talk about infill, we usually think of it as being uniform inside the part. However, this is not necessarily the only way.

Using gradient infill you can set the print to have a higher infill density toward the edges. Generally speaking, this approach should preserve the effective strength and rigidity of the part while using less material. This setting is not natively available in Cura, but it can be achieved relatively easily using a Python script.

Gradient infill should not be confused with gradual infill, which does something similar but along the Z-axis instead of the X and Y axes. In other words, this setting makes the infill denser closer to the top of the print than at its bottom. This can save material and time while still providing sufficient strength at the end that requires rigidity.

Custom tiled infill

Top left to bottom right: Fill, Cura, Continuous and Normal Honeycomb (Source: Ultimaker via GitHub)

Those who miss the Honeycomb infill popular in other slicers, such as PrusaSlicer, can breathe a sigh of relief, as Cura improved its plugin capabilities in version 5.5. This update enabled the creation of a plugin for custom infill patterns. Although it is still in beta, CuraEngine Tiled Infill Generation comes preconfigured with infill patterns such as Honeycomb and the Cura logo.

Users also have the option of adding their own custom infill patterns directly to the Infill Pattern drop-down menu. Patterns must be in *.wtk format and will be arranged as tiles, so you do not yet have complete freedom when designing them. Nevertheless, it is great for creating aesthetic infills, such as a soap dish, as shown in the 3D printing example. More information can be found in the documentation on GitHub.

Multiple infill densities
Since the release of the fourth version of Cura, it has been possible to set the “infill density for each model”. This feature is useful because it enables some interesting design tricks, including using multiple infill densities and types in the same print, as shown in the video below. Although there may not be many specific applications for this type of flat, coaster-like infill, we think this method hides more possibilities than initially meets the eye.

With the option to set custom settings for each imported model and Cura’s ability to combine them seamlessly, it seems possible to provide specialized support in specific areas, although this certainly means a lot of manual work.

Skin
Skin refers to the top and bottom layers of the model. It can affect the amount of material and print time, as well as the model’s strength and weight. Regarding infill, one setting that can be changed is the “Skin Overlap Percentage” (skin overlap percentage), which controls how much the walls overlap with the internal infill. The higher this percentage, the more the infill will be connected to the model’s outer surface, making the model less brittle.

If you want to reduce the number of layers, you can change the “Skin Removal Width” (skin removal width). The value you enter will be removed from the top and bottom layers. This is visible, for example, in slimmer or smaller designs or details where strength is not necessary.

Fast prints
There are several ways to achieve faster printing by adjusting infill settings. For example, infill lines are usually printed at a 45-degree angle, allowing the X and Y motors to reach maximum speed. Infill layer thickness can also affect print speed. You can adjust this setting to a thicker layer height, thereby reducing print time.

You can also experiment with different patterns to reduce print time. Generally speaking, the “lightning” pattern leads to the fastest prints. If your print does not require mechanical stability, you can use this pattern to achieve a 25% faster print. Patterns such as concentric, grid, and triangles are also relatively simple and should result in fast prints.