UltiMaker Cura - Infill settings

This article describes the various infill settings in UltiMaker Cura. These settings are available when opening the Custom mode.

Infill refers to the internal structure of a printed object, which is filled with a pattern or mesh to provide strength and stability while minimizing material use. The infill percentage and pattern can be adjusted to achieve a balance between strength, weight, and print time. A higher infill percentage results in a denser, stronger print, while a lower percentage makes the object lighter but potentially less durable. Infill patterns, such as grid, cubic, or gyroid, influence not only the strength and flexibility of the final print but also how efficiently the object is produced. Understanding and optimizing infill settings is crucial for achieving the desired mechanical properties and material efficiency in 3D printed objects.

Tip: Some infill settings can be chosen in the Recommended print settings overview (density and pattern). Other settings are altered in the Custom view.

Infill Extruder

If your printer supports printing with multiple extruders, you can select with which extruder you want to print the infill material. Use a different material to change the mechanical properties of your object, or use a bigger nozzle size for the infill pattern to increase the printing speed and strength without decreasing the visual quality.

Infill Density

This setting configures the density of the volume inside the print, which is a major factor in the strength of the final print as well as the top surface quality. The greater the infill density, the closer the infill lines will be placed together.

Increasing the infill density has a big effect on your print and printing strategy:

• Pro: The print will be stronger.
• Pro: The top surfaces will be supported better, making the model smoother and more water tight.
• Con: The print will require more material, also increasing the cost and weight of the object.
• Con: The print will take more time to complete.

Note that different infill patterns (see below) benefit from different infill densities. If you want to print your object close to or completely solid (Infill Density = 80-100%), it is best to select a pattern with straight lines, such as Lines or Zigzag, or other non-overlapping shapes such as Concentric.

Tip: After slicing, always check the Preview mode to ensure that your chosen infill density works well for your model and all surfaces are correctly supported.

Image above: The model on the right has a higher infill density than the model on the left.

Infill Line Distance

This is a subsetting of Infill Density. Instead of setting the infill density as a percentage, it is also possible to set the line distance. This determines the distance between each infill line, which has the same effect as changing the infill density. A larger distance between the lines lowers the density.

Normally, the infill line distance is computed based on the selected density and line width. This setting is always leading, also when this is changed manually.

Infill Pattern

UltiMaker Cura allows you to change the pattern of the printed infill structure. Various patterns are available, each with their own benefits. Some can be used for most objects, while others are developed for very specific applications. Select the pattern (and density), which best serves your model and application.

Grid Type: 2D infill Good for: General applications The grid infill pattern creates two perpendicular sets of lines. Together this forms a pattern of squares. This is a very strong pattern in the vertical direction and offers great top surface support.	Lines Type: 2D infill Good for: Visual models The lines pattern creates parallel lines. By default, the lines pattern alternates its direction perpendicularly from layer to layer. This infill is weak, but the lines are printed close together without costing a lot of material, enabling excellent top surface support.	Triangles Type: 2D infill Good for: General applications This pattern consists of three lines in different directions, creating triangle pockets. This offers equal horizontal strength in each direction, but needs more top layers to get an even surface. The intersections cause flow interruptions, making this pattern unsuitable for higher densities.
Tri-hexagon Type: 2D infill Good for: General applications This pattern consists of three lines in different directions, but offset so they don't all intersect at the same point. This is the strongest pattern horizontally, with equal strength in every direction. This pattern requires more top layers to get an even surface.	Cubic Type: 3D infill Good for: Visual and engineering applications This pattern creates 3 dimensional cubes, standing on a corner. This offers good strength, equal in all directions. A benefit is a reduced pillowing effect, as this does not produce long pockets of air.	Cubic subdivision Type: 3D infill Good for: Visual models, material saving This pattern creates 3 dimensional cubes, standing on a corner. Towards the center, the cubes are bigger to save on material. This offers a great balance between strength, visual quality, and material usage. The pattern is more complex, so may take longer to slice.
Octet Type: 3D infill Good for: Engineering applications The octet pattern creates a combination of regular tetrahedra and cubes. Every so often, multiple infill lines will be placed adjacent to each other. This creates a strong internal frame that quickly dissipates load. This pattern has reduced pillowing, but needs many top layers due to long bridging distances.	Quarter Cubic Type: 3D infill Good for: Engineering applications The quarter cubic pattern creates a 3-dimensional tesselation consisting of tetrahedra and truncated tetrahedra. Like the Octet infill pattern, it creates an internal frame to which loads can be dissipated. The quarter cubic pattern is especially suitable for thin functional parts.	Concentric Type: 2D infill Good for: Flexible models This pattern creates rings parallel to the walls of the object. It supports top surfaces, but offers no strength in the horizontal direction. It is very suitable for flexible materials and objects that should bend. When printed at 100% infill, this pattern is actually the strongest .
ZigZag Type: 2D infill Good for: Visual models This pattern, line Lines, creates parellel lines on alternating layers. The lines are connected, preventing flow interruptions. This infill is weak, but the lines are printed close together without costing a lot of material, enabling excellent top surface support.	Cross Type: 2D infill Good for: Flexible models The cross infill pattern produces a space-filling curve along the inside of the volume. It is great for flexible objects, as it requires no retractions and is evenly squishy in all horizontal directions. The print will be stronger in the horizontal direction.	Cross 3D Type: 3D infill Good for: Flexible models This infill pattern produces a space-filling curve along the inside of the volume, and pulses along the Z axis in order to make it weaker in the vertical direction. This will be almost equally squishy in all directions, making this the most suitable for flexible parts.
Gyroid Type: 3D infill Good for: Flexible models The gyroid infill pattern produces a wavy pattern that alternates directions. It is equally strong in all directions, but not very stiff. This makes it useful for flexible materials, but prints will be harder than with Cross (3D) infill. The gyroid pattern looks very interesting, so is also favored for its looks. Note that this can take very long to slice and produces large gcode files.	Lightning Type: 3D infill Good for: Material saving The lightning infill produces a jagged minimal pattern which only supports the top surface. It builds up and branches out like a lightning bolt. This saves a lot of material, but does not add any strength and may be unstable in larger volumes.

Tip: More infill patterns, including Honeycomb, are available via this Cura plugin. You can also add your own custom infill patterns by adding *.wtk files.

Connect Infill Lines

This setting connects the endpoints of the infill pattern, where the infill meets the inner wall or skin, using a line that follows the edge of the infill area. This reduces the amount of retractions as it converts the infill pattern into as few individual lines as possible. A major benefit of this is a more constant flow rate, which improves print quality and strength of the infill structure. Overall model strength is also improved when this setting is enabled, as it prints extra material along the walls which also helps to make the infill adhere better. The downside is that it takes longer and more material to print.

Image above: The model on the left uses Grid infill with Connect Infill Lines disabled; the model on the right has this setting enabled.

Connect Infill Polygons

When the infill consists of closed loops, these closed loops can be fused together to form one single loop. Enabling this setting will make small connections where polygons are adjacent.

This setting is only available when the infill consists of loops that are adjacent to each other. That means that either:

• The infill pattern is set to Cross or Cross 3D.
• The infill lines are multiplied to an even number (see Infill Line Multiplier below).
• There are at least 2 extra walls around the infill (see Extra Infill Wall Count below).

The aim of this function is to prevent travel moves. The final line will be one single loop for every connected part of infill, so there will not be any travel moves. This makes it easier to work with flexible filaments, because those are harder to retract and work best if they can keep flowing through the nozzle.

Connecting these loops can also make the infill stronger by enhancing the connection between the loops internally. However, this may introduce a lot of 180 turns, which may weaken the connections. This setting's impact on strength depends on how the loops mesh out through the shape of your model.

Image above: The model on the left has two-lined Triangle infill; the infill lines are isolated shapes. The model on the right has Connect Infill Polygons enabled; the infill forms a continuous line.

Infill Line Directions

The infill lines usually print at a 45° angle. At this angle, both the X and Y motor work together to obtain maximum acceleration and jerk on the layer without losing quality. You can customize the direction of the infill line to increase strength, optimize acceleration, or for visual effects.

To change the direction, enter your desired value(s) between the brackets. If you want multiple angles, separate them with a comma. For example: [0,45]. The angles will be alternated per layer.

Tip: When selecting angles for your line directions, note that 0° is parallel with the Y axis and 90° is parellel with the X axis.

Infill XY Offset

Infill patterns are normally centered for each 3D model. You can apply an offset for the X and/or Y direction to control where the infill will be placed. Especially for lower infill densities, this setting can be useful to position infill lines exactly where they are needed. As seen from above, a positive value moves the infill pattern UP and RIGHT, while a negative value moves it DOWN or LEFT.

Note:This does not work for the Concentric infill type.

Randomize Infill Start

With this setting enabled, the position where the infill will start printing is randomized for each layer. Normally, the infill line closest to where the nozzle was will be printed first. However, the infill is often printed at higher speed and/or with thicker layers. This sudden change in required flow may impact the strength of the infill the very first part of the infill line; this could show some under-extrusion. Randomizing the starting position of the infill spreads out these possible weak spots, increasing the overall strength of the object.

Infill Line Multiplier

By increasing this setting, Cura will place down more infill lines directly next to the other infill lines. This effectively increases the infill density beyond what the Infill Density setting specifies, but instead of spacing the infill lines out evenly, the lines are placed directly adjacent to each other. Compared to increasing the infill density, this may increase the strength of the infill since the infill lines are able to lean on each other for extra rigidity. However, when using Infill Line Multiplier instead of increasing the density, this may have a negative effect on the outer surface of the print.

Tip: If the multiplier is set to an even value, the option Connect Infill Polygons becomes available.

Image above: The model shown above has an infill multiplier value of 3.

Extra Infill Wall Count

This setting adds a number of contours around the infill areas. This is similar to increasing the number of walls or adding an extra skin wall, but the contours will be placed around the infill structure. These walls are printed with the infill settings.

Adding one or more infill walls greatly increases strength of the model and reduces the visibility of infill through the skin, but also increases printing time and material usage.

Tip: It is a good idea to add at least one extra wall around either the infill or the skin, because it prevents the skin lines from ending in mid-air.

Image above: The model on the left has two extra walls around the infill structure. For comparison, the model on the right has two extra walls around the skin.

Infill Overlap (Percentage)

With this setting you can control the amount of overlap between the infill and walls. It can be set as a percentage or as a value in mm. A higher value usually results in better bonding between the infill and walls, making the part stronger. However, it might also reduce the visual quality of the print, because the infill could show through the outer walls. This results in a pattern on the outer surface of the print.

Image above: A visualization of the infill overlap and wipe distance.

Infill Wipe Distance

This setting will make the nozzle move a little bit further than the end of the infill line with a small travel move. The aim of this small travel move is to wipe off the material onto the wall next to it. This fuses the infill line to the wall better. See the image above for a visualization.

While this travel move makes the object stronger, the main disadvantage is that this travel move goes through the wall which leaves a visible mark on the outside of the print. This strengthens the effect of the infill being visible on the outer surface of the objects.

Note: This setting only applies to the ends of the infill lines. When using connected infill lines, there will be much fewer ends.

Infill Layer Thickness

Since the layer height of the infill is not important for visual quality, you can use thicker layers on the infill to reduce the print time. This setting causes layers of infill to be combined together, as long as there are multiple layers of infill directly above each other. It will then not print any infill on some of the layers, but in the highest of the combined layers it will extrude more material to make up for it. For example, when your layer height is 0.1 mm and the infill is 0.2 mm, the printer will first print two layers of walls (and skin and/or supports, if applicable), and then it will print one thicker infill layer.

In layer view, it will look as if the infill lines have become much wider. When actually printed, the infill lines will drop down further instead of spreading out horizontally.

The Infill Layer Thickness must always be a multiple of the normal layer height. If a different value is selected, Cura will round off to the closest multiple.

Note: If the difference between the Layer Height and Infill Layer Height is too big, this requires a big change in material flow when switching to and from printing the infill. This could cause some under and over-extrusion issues in these places.

Image above: The model on the left has equal layer heights throughout, and the model on the right has an Infill Layer Height of twice the normal Layer Height.

Gradual Infill Steps

Gradual infill reduces the amount of infill used by decreasing the infill density in the lower layers. This saves on printing time and material usage, while still offering a dense support below any top surfaces. Note that this will decrease the strength of the infill structure and the object, and should be used for visual models only.

This setting indicates in how many steps the infill density gets reduced. At every step, the infill density is halved. For example, starting with an infill percentage of 20 % and two gradual infill steps, the infill density of the lower parts will be 10 % and 5 %, respectively.

Image above: The model on the left has normal infill, and the model on the right uses Gradual Infill Steps.

Gradual Infill Step Height

This setting controls the height of each of the gradual infill steps. It is only visible if Gradual Infill Steps is set to 1 or higher.

The gradual steps are calculated from the top down. After reaching the height specified in this setting, the infill will be halved. For example, let's say if you are printing an object with the following settings:

• Layer Height / Infill Layer Height = 0.15 mm
• Infill Density = 40%
• Gradual Infill Steps = 2
• Gradual Infill Step Height = 1.5 mm

Then, just below the top surface, the infill will be printed at 40% density for 10 layers. During the next 10 layers, the infill will have 20% density. For the rest of the print (below), the infill density will be 10%.

Especially after large density transitions, it is normal that some infill layers will not be supported and will print in mid-air. These first layers will only attach to the sides of the print and the previously printed infill structure. Since the visual quality of the infill is not important, this usually does not cause any problems. This will take a few layers to get better. You can increase the step height to give the infill structure more chance to repair itself before the next transition or before printing the top surfaces, but this will take more material.

Infill Before Walls

This setting affects the order in which different parts of the model are printed. If this setting is enabled, the infill will be printed before the walls. When disabled, the walls will be printed first. Both options have their benefits and downsides, and which is best depends on your application. It is mostly a trade-off between accuracy and strength:

• Disabled (walls first): If the walls are printed before the infill, the walls could have nothing to attach to, causing them to sag more. However, the walls will have solidified first and will not be pushed away by the infill, which prevents the infill from shining through the walls.
• Enabled (infill first): If the infill is printed before the walls, the walls will get pushed away where infill is attached to the walls, which makes the walls less accurate and can cause the infill to shine through the surface, creating a pattern visible on the outside. However, the infill will hold the walls in place better while they are printed, leading to better overhangs.

Minimum Infill Area

This setting allows small areas on a single layer to be printed with skin instead of infill, to make them fully solid. This is especially useful on models with thin pieces that require more strength, without increasing the overall infill density or using cutting meshes.

Image above: This coupler has thin pieces. The image in the middle has normal infill (Minimum Infill Area = 0), which leaves some open areas. The image on the right uses a Minimum Infill Area to strengthen the legs of this coupler by filling them completely with skin.

Infill Support

When enabled, this treats infill as support. Infill will then only generate where it is needed in order to support the top surface. It behaves as if the model is hollow and generates support inside it, but this support is generated using the infill settings. See the image below for a visualization.

For some models, this saves a lot of material with little impact to the visual quality. However, the strength of the object is greatly reduced. Especially if there are steep slopes in the model, there will often be no infill behind the walls. This setting should be used for visual models only.

Infill Overhang Angle

If Infill Support is enabled, you can set an overhang angle, similar to the support overhang settings. This setting is not visible if infill support is disabled.

This determines the minimum overhang angle of the surface that needs to get supported with infill. Increasing this angle will cause the infill to support less of the top surface. This saves on printing time and material, but will cause the top skin to sag a bit more.

• A value of 0° will act like normal infill. It supports everything.
• A value of 90° will remove all infill material.

Image above: This shows the differences between infill support settings. The model on the left has Infill Support disabled; the entire object is full of infill. The model in the middle has Infill Support enabled with a low/medium setting for Infill Overhang Angle; only the very steep angles are not supported with infill. The model on the right has a high value for Infill Overhang Angle; only the almost horizontal surfaces are supported with infill.

Skin Edge Support Thickness / Layers

When printing concave shapes, there will be some parts of the top skin that end somewhere halfway through the infill. These lines will not be supported properly and may sag. This setting adds an extra line through the infill to support the edge of the skin. A single line through the gaps in the infill will still sag, so the line may be drawn on multiple layers underneath the edge of the skin that needs support.

This setting configures the vertical thickness of the line underneath the edge of the skin. Alternatively, you can directly adjust the number of layers underneath the edge of the skin where this line will get drawn. Increasing this setting will offer better support for top layers, creating a smoother surface, but this will take longer to print and cost more material.

Note: If the Infill Density is very high, there will be few to no spots in the infill that benefit from this extra skin edge support line. This may even cause over-extrusion in the infill, so it is best set to 0 in these cases.

Image above: The model on the left has normal infill; some areas of the skin may sag a little. The model on the right uses Skin Edge Support to generate extra infill lines to support details in the top surface.

Tip: Continue learning about all UltiMaker Cura custom settings. The next section is Material.