What Is the Support Blocker Feature in Cura? (How to Use?)

There are many factors that determine the success of a printing process before the 3D printer even starts operating, with factors such as the model design, the printer configuration, and the print-specific settings all playing critical roles in producing a high-quality 3D printed model.

For print-specific settings, in particular, the slicer you’re using primarily takes the spotlight, as the extent of the features that the slicer offers practically decides how well you can configure and customize these settings and really shape how the model will come out to be suitable for your purposes.

In today’s article, we will be talking about a particular feature in Cura slicer that takes print-specific configuration a step further, known as support blockers, which is a component that essentially gives the user complete control of the supports, bringing a great deal of flexibility to optimizing the model before the printing process.

So, what does the support blocker feature of Cura really do?

The support blocker feature in Cura allows you to specify the parts of the 3D model that you would prefer not to have support structures beneath them, which makes it possible to manually exclude particular areas of your choice from having supports that would otherwise be automatically supported.

Moving forward, we will further analyze the support blocker feature in Cura, find out where to find and how to use the support blocker feature, go through the process of changing the size of the support blockers, and finally, take a look at an alternative way of using support blockers for changing the infill density of the model.

What Is the Support Blocker Feature in Cura?

While its purpose may not be too apparent at first look, the support blocker feature in Cura plays a vital role in the customization of the printing process.

When you enable support generation in and slice a model, Cura will automatically locate all the bridges and overhangs present and place support structures below all the areas that satisfy the minimum overhang angle rule, determined by the Support Overhang Angle parameter.

While this makes support generation extremely convenient, as it practically makes it impossible to place support structures where they aren’t needed or miss the placing of support structures in areas where they would be required, it’s possible to come across cases where a more manual approach can be necessary.

The support blocker feature of Cura comes in at this exact point, allowing you to mark the exact areas that you would like to be exempt from support generation, which causes Cura to disregard these areas when conducting the automatic support generation process even if they meet the necessary criteria.

This way, with an approach that is based on the manual exclusion of the areas rather than the manual addition of the support structures, it becomes possible to enjoy the benefits of automatic support generation in terms of both practicality and reliability without the downside of the possibility of ending up with support structures in places where they wouldn’t be necessary.

Where to Find and How to Use the Support Blocker Feature in Cura?

Even though the support blocker feature is conveniently placed and pretty straightforward to use, you may not notice it at first look unless you pay close attention to the Cura interface.

Below, you can find a step-by-step guide that will take you through the process of locating the support blocker feature and correctly utilizing it:

  1. Left-click the 3D model that you will be adding support blockers.
  2. Click the Support Blocker tab from the left menu (2nd from the bottom).
  3. Click on the part of the 3D model where you would like to add the support blocker.
  4. Left-click the support blocker you have just added, and move it to the exact spot you would like it to be by using the Move tab, similar to how you would move a standard 3D model.

After adding the support blockers in the desired places, you can slice the model and navigate to the Preview tab to find out whether the support blockers are correctly positioned, as these areas should not have any support structures beneath them (labeled as Helpers in the default color scheme) if all is working as intended.

How to Make Support Blockers Larger or Smaller in Cura?

As the default size that the support blocker comes with is not always appropriate for usage, making it larger or smaller becomes a necessity to be able to achieve our goal.

The process of changing the size of a support blocker is no different than scaling any standard 3D model that you have imported into Cura, meaning that all you will need to do is to click it as you usually would and apply the correct scaling.

If you are unsure about how to conduct the scaling process, below, you can find a step-by-step guide that you can follow to scale support blockers or any other 3D model that you have imported into Cura:

  1. Left-click the support blocker you have added, which will allow you to select it like any other imported 3D model.
  2. Navigate to the Scale tab on the left menu (second from the top).
  3. Scale the support blocker by pulling the lines, inputting into the millimeter field, or inputting into the percentage field, just as you would with a regular 3D model.

Aside from scaling, you can also apply rotation by navigating to the Rotation tab if you wish, as the support blocker behaves practically no differently than a standard 3D model regarding manipulation.

How to Use Advanced Support Blockers (Per Model Settings) to Change Infill Density in Cura?

Even though the support blocker feature, at its core, has a clear purpose, there are alternative ways to utilize the feature to customize your prints even further.

Below is a step-by-step guide you can follow to utilize advanced support blockers that will allow you to block supports in a more customizable way compared to standard support blockers:

  1. Import the 3D model you would like to use as a support blocker.
  2. Left-click the model you have imported.
  3. Navigate to the Per Model Settings tab located on the left menu (5th from the top).
  4. Click the Don’t support overlaps option (1st from the right) to turn the model you have imported into a support blocker.
  5. Move the support blocker into its desired location, and apply scaling and rotation as necessary.

This way, you will be able to specify the shape of the support blocker explicitly, as opposed to using the cube shape that comes with the default support blocker feature, which will allow you to block the supports in practically any form of your choice.

Wrapping Up

The support blocker feature in Cura is, without a doubt, one that offers an incredible amount of flexibility to the printing process when used correctly, opening up a considerable number of possibilities to take your prints a step further.

To quickly recap, the support blocker feature in Cura makes it possible to exclude particular areas of the 3D model from being affected by automatic support generation, causing the areas that you have marked with the support blockers not to have any support structures generated beneath them.

As a result, we can practically say that Cura gives you complete control over the automatic support generation with the support blocker feature, allowing you to manipulate the support structures in a way that will enable you to utilize the benefits of automatic support generation while not being affected by its downsides.

Happy printing!