Some models have overhanging parts, which means that parts of the model float mid-air when you would print the model. In this case, you must print a support structure under the model to prevent the plastic from falling down. This can be achieved by enabling “Generate support”.
Dual extrusion machines offer the possibility to create water-soluble supports. To make use of this feature, you can specify which parts of the support are printed with which extruder. The setting is divided into:
- Support infill extruder
- First layer support extruder
- Support interface extruder
- Support roof extruder
- Support floor extruder
The support infill extruder is indicated in red.
The first layer support extruder is indicated in red.
The support interface extruder is indicated in red.
Ultimaker Cura offers two techniques to generate support called 'Normal' and 'Tree'. The 'Normal' support generates supports directly below your 3D model and is used in all Ultimaker printing profiles.
As an alternative, 'Tree' support creates branches that grow around your 3D model. The benefits of this alternative include reduced print time and less scarring of the model.
The model on the left has 'normal' support, the model on the right has 'tree' support.
Caution: While 'Tree support' has advantages, the system has not been tested throughout and does not include profile-specific parameters.
Instead of printing supports up in straight lines from the build plate, we can use tree support to print tree-like structures that support models. These supports are hollow and can be designed to follow different angles. The following parameters control the way the supports grow.
- Tree support branch angle: The maximum overhang angle the branches may use to print sideways. An overhang angle of 40° is considered reliable
- Tree support branch distance: The distance between the endpoints of branches, for example, where they touch the model. It is comparable to the support density
- Tree support branch diameter: The diameter of the branch where it touches the model. Wide branches are stable yet hard to remove, thin branches are less stable yet easy to remove
- Tree support branch diameter angle: The growth angle of the branch. A bigger angle increases the branch’s bottom width
- Tree support collision resolution: The X-Y resolution to check the loaded model and avoid collisions. The default of 0.2mm works fine, if you wish a 'smooth' tree support finish a higher resolution may be applied
This model has been sliced with the default tree support parameters.
This setting defines where the support structure is printed. It contains the following options:
- Touching build plate: Support material is only printed from the build plate up
- Everywhere: Support material is printed below every part that needs support, which means that it can also be placed on or inside a model
This model has parts with overhangs. The model on the left has support everywhere, while the model on the right has support on the build plate only
The overhang angle influences how much support material is added. A smaller angle leads to more support. For example, at a value of 0° all overhangs are supported, while at 90° no support material is added.
The model on the left is shown in the solid mode. The red areas indicate the overhang area that needs support. The model in the middle has an overhang angle of 70°, while the model on the right has an overhang angle of 45°
There are different patterns available for printing support structures, resulting in sturdy or easy to remove support. You can choose from the patterns below:
Support wall line count
The support wall is a perimeter printed around the support pattern. This wall adds strength to the outer parts of the support structure to improve reliability, mainly used for printing PVA material. When printing supports with the build material, removal of support is more important, and no extra support wall is used.
The model on the left has supports printed with PVA, it requires a support wall. The model on the right is printed with the build material, it does not have a wall to ease the post-processing
When a zig-zag support pattern has been selected, this setting becomes visible. It connects the end of zig-zags, which strengthens the support structure and increases adhesion to the build plate by the support structure.
This defines the density of support structures. A higher value will lead to stronger support, but these will be more difficult to remove and take more time to print.
This model has triangle support with three different densities: 15 %, 30 % and 45 %
Support line distance
The support line distance is a child setting of the support density; instead of calculating it as a percentage, it allows to set the distance between supports directly. This setting can be seperately adjusted for the initial layer.
Support infill line directions
This feature rotates the support pattern by the set degree angle. This allows to rotate the support structure to a more beneficial alignment with the model. This works for all support patterns.
The model on the left has the default direction of 0°, the model on the right has a support infill line direction of 45°, resulting in a vertical pattern
The support brim adds a number of concentric layers on the inside of the support structure on the initial layer, similar to the model brim. It improves the adhesion of the support material to the build plate, improving its reliability.
The model on the left has the default 8mm brim for PVA material, the middle model has it reduced to 3mm and the model on the right completely disabled
This refers to the distance from the top and bottom of the support structure relative to the model. This setting is divided into the top distance and bottom distance. The top distance defines the distance between the top of the support and bottom of the model and the bottom distance refers to the distance between the bottom of the support and top part of the model.
A small distance between the support structure and parts of the model is necessary in order to remove the supports easily after the model has been printed. A low value creates a smoother surface, but can also make it more difficult to remove the support properly.
Under this setting you can adjust the distance between the support structure and the model in the X and Y directions. A higher value reduces the chance of the support structure hitting the model. However, this also creates a larger distance between model and support structure, which may result in smaller overhangs not being fully supported.
The model on the left has a support X/Y distance of 0.7mm, while the one on the right has one of 0.3mm
Support distance priority
After the launch of Ultimaker PVA, the support Z-distance was set to 0. This introduced a scenario where the X/Y-distance would offset the PVA from the model, decreasing the support quality. The support distance priority ensures that the PVA aligns with the model perfectly. The image below shows the priority when X/Y overrides Z, and when Z override X/Y.
Minimum support X/Y distance
When the Z overrides the X/Y-distance priority, as discussed above, the X/Y-distance may force the support to hit the model. To ensure a safe distance, the minimum support X/Y-distance should be kept at all times.
Stair step height
When “Support placement type everywhere” is selected, support structures are printed with the model. This structure doesn’t necessarily follow the contours of the model smoothly. Instead, the bottom of the support structure consists of small stair-like steps. Changing the stair step height value affects how big these steps should be. A low value will result in a smoother bottom of the support and more connections between the model and support structure. A higher value makes it easier to remove the support afterwards.
The object on the left has a high value stair step height, the model on the right has a lower value
Support stair step maximum width
This is the maximum width in the X/Y direction where a stair step appears. When a plane does not change height within these 5 millimeters, the support is handled as regular support.
Support stair step minimum slope angle
With this setting you can disable stair stepping on the very bottom of the support, up until the slope of the model has a certain angle. If there is a small valley that the support rests in, it can even just cause the whole bottom side to skip, making the entire support rest only on the corners of the stair steps.
For those cases, you can limit the stair steps to occur only on the steeper slopes. This setting decides what constitutes a "steep" slope in that regard.
Join distance is the maximum distance between support structures in the X/Y directions. When separate structures are closer together than this value, they will merge. Using a high value for this setting will cause support structures will merge sooner. This can help increase the stability and strength of the support, especially when the support structures are very thin. It is important to note that a high value can make the support structures so dense that it is difficult to remove.
The model on the left has separate supports, while the support join distance value of the right model cause the supports to merge
Support horizontal expansion
By using horizontal expansion, an offset can be applied to support structures in the X and Y direction. High values will expand the support areas, resulting in sturdier support. Very thin support areas can be removed completely by using a negative value. The right side support of the model below can easily be printed, although the supported area is very thin.
The model on the left has horizontal expansion disabled which saves material and decreases print time. The model on the right has horizontal expansion enabled, which increases the strength of the structure
Support infill layer thickness
Support infill can be printed two layers at a time; it does not need to be visually appealing since it’s removed after printing. This can be done by setting a support infill layer thickness to a multiplication of the layer height.
The model on the left has a regular support infill layer thickness of 100 micron, the model on the right has a double thickness, 200 micron
Gradual support infill steps
Gradual support works similar to the functionality of gradual infill. Each gradual infill steps divides the infill density by two, resulting in a lighter infill at the bottom and dense infill towards the top. Gradual infill improves support cost and efficiency without the impairment of visual quality.
This model is printed with two gradual infill steps of 1mm each. The supports get denser 1mm and 2mm below model surfaces
Minimum support area
This setting defines the minimum footprint area supports need to cover, before being ignored. By default, all areas in need of support are printed. When thin support structures occur in unwanted places, they can be filtered out.
The model on the left has all supports in place, as is default. The model on the right has a minimum support area of 3mm^2, ignoring the thin overhang areas
Enable support interface
A support interface generates a dense skin on the roof and floor of the support structure on which the model is printed. Doing this supports the bottom layer of the print better, leading to a more even surface. It is important to remember that a support roof is more difficult to remove than regular support, so post-processing may require more work, specifically when using non-soluble supports.
This model is sliced in two different ways: the example in the middle has the support interface enabled, while the right example has the support interface disabled
The support roofs and floors can be set separately and each has its own options:
- Support interface thickness: The thickness of the support interface(s)
- Support interface resolution: The resolution checked in the Z-direction, which determines where support interface is printed
- Support interface density / line distance: The density of interface of the support structure
- Support roof pattern: The pattern that determines how the roof of the support structure is printed
Fan speed override
When enabled, the print cooling fan speed is altered for the skin layer directly above the support. A higher fan speed makes the supports easier to remove.
By enabling this setting, support structures are printed as towers that reinforce tiny overhang areas. Support towers are only printed for support areas that are smaller than the set minimum diameter. All support areas larger than this value will use regular support.
The model on the left has the default value of ‘use towers’ enabled. The model on the right has the setting disabled.
Tower diameter, maximum tower-supported diameter and roof angle
The characteristics of the support towers can be altered with three parameters. The image below illustrates how the changes of each setting affect the tower.
Continue reading about Build Plate Adhesion settings.