How to Use Cura Support Blockers Properly

The Cura support blocker is a feature that allows you to block support in specific areas before you print. Using the Cura support blocker properly saves time and filament when you print.

This article will take you through the process of using Cura support blockers and address reasons your Cura support might not work properly.

How to Use Cura Support Blockers

If you have supports you think your print doesn’t need, then using the Cura support blocker is a way to get rid of those supports.

To explain the Cura support blocker, I will use an “among us” model as an example to simplify the process.

To use the Cura support blockers:

• Load your Model
• Slice and Preview Model
• Select Support Blocker
• Modify the Size of the Support Blocker
• Adjust the Position of the Support Blocker
• Preview and Slice Model

Load Your Model

First off, load your model into Cura, then select the top right-hand side of your panel to access your print settings and click on it. On the drop-down menu that appears, click on the “generate support” button to enable support for your model.

Also, adjust your “support overhang angle,” which is the angle at which you want your printer to support your model. There isn’t a standard number because it depends on the model and your 3D printer, but an ideal place to start is 45 degrees.

Slice and Preview Model

After selecting support, slice your model to get the time and the amount of filament it will take to 3D print your model.

After slicing, select the preview button on the panel directly above the model. Your model should change from bright yellow to a red color and the support from red into a bluish hue.

The preview shows you different angles of your model in layers, allowing you to see parts that need support.

Click on the vertical bar on the right-hand side of your Cura interface with a number on top. Move the little circle knob down to reveal your model in layers.

Select Support Blocker

After previewing your model to see where you need the support and where you don’t, shift back to “Prepare” and select the support blocker icon. The support blocker is the last icon on the panel on your left-hand side of the screen.

Then, choose it and click on the area where you don’t need the support to create a small gray box. In this model, the support blockers go on top of the Among Us model bottom piece and the underside of the model’s head piece.

Modify the Size of the Support Blocker

Under the support blocker icon, there is an icon named “object list,” which has the name of the model and the support blockers known as erasers.

To modify the size of the support blockers, you need to highlight it on the object list and then select the second icon on the panel on your left-hand side of the Cura interface to access another panel with the values X, Y, and Z.

You can adjust the values on these axes to increase the to cover the support.

Turn off your uniform scaling options to move the different values individually and not as a group. You can also use your cursor to drag the red, green, or blue boxes extending from the support blocker to increase its size.

One support blocker without extending its axes is enough for the support on the bottom half of the Among us model, but the head needs its support blocker to be extended to cover the whole area.

Adjust the Position of the Support Blocker

After changing the size of the support blocker, you want to check that it’s positioned in the correct place. You can adjust your Cura view by holding the right click mouse button and dragging the mouse around.

Then you can zoom in or out using the control wheel or a laptop touchpad scroll function.

Be as precise as you can when putting your support blocker on the support to successfully remove the support after slicing.

After getting your preferred angle and position, adjust the model’s vertical, horizontal, and sideways placement of your support blocker.

To do this, select the first icon on the panel on your right-hand side to move the support blocker vertically, horizontally, or sideways. You want your support blocker placed on and around the red points.

Preview and Slice Model

After adjusting the support blocker so that it’s blocking all the red support on the model, slice it.

Aim to have a model with no support where you placed the support blocker. You shouldn’t see the bluish hue anymore in the preview setting, signifying you have successfully removed the support from your model.

You can see this in the before and after images of the slice model. The bluish hue support blockers were present in the before models but were absent after applying the support blockers.

The other difference is the slight change in the print time and quantity of the material used. Due to the model’s small size, the difference isn’t too obvious.

You can check out the video below by Learn As We Go, which shows you how to use support blockers.

Here is a tip you can use when using the Cura support blocker function to block space in-between objects or holes. One way of using the support blockers when blocking holes is to use one support blocker for every support (red spot) in the hole.

Another method is to use one support and adjust its width, length, and breadth to block all the red points in the hole.

The picture above shows an example of using individual boxes to close up every support in a hole. The arrows point to two support where the support blockers are used.

It’s also important to know that since the support would not be attached to the bed, you don’t need the boxes extending to the bed.

You can check out the video below by PRO 3D, which shows you how to use support blockers to block individual holes.

In this second diagram, one support blocker was used to block multiple supports in a hole by extending the X, Y, and Z axis.

You can watch the full video of blocking the holes in a model by extending the axis of the support box by Astro printer with the link.

How to Fix Cura Support Blockers Not Working or Showing

Here’s how to fix Cura support blockers not working or showing:

• Repair a Faulty Model
• Reinstall Cura
• Disable Support Towers
• Properly Position Your Support Blocker
• Adjust the Minimum Support Area Setting

Repair a Faulty Model

One way to fix your Cura support blockers not working or showing is to repair a faulty model.

A user who had these issues found that he fixed the issue by using the auto-repair function on Microsoft 3D Builder.

Another user figured out that having his 3D model as a 3MF file was an issue. He had to re-save his file as an STL file for the support blockers to properly work.

One user who struggled with support blockers had to re-save his file as an STL from a 3MF to work on his model.

Reinstall Cura

A simple fix that worked for one user was to simply reinstall the Cura software.

One user who had a challenging time using his Cura support blocker solved the problem by re-installing the software.

Disable Support Towers

Another way to get your Cura support blocker working again is by disabling the “Use Towers” function in support setting. You can do this by searching for “Use Tower” and unchecking it.

This was the solution for a user who struggled with unnecessary support that he couldn’t get off with support blockers. He disabled it and immediately got results.

One user who struggled with supports outside his model also disabled his support tower and got his desired result.

Another user suggested using a negative support horizontal expansion alongside disabling the “Use Tower” function.

Properly Position Your Support Blocker

Another way to get your Cura support blocker working again is by positioning your support blocker the right way.

A user who struggled with his support blockers realized he wasn’t placing them in the right way. He resized the support blocker to cover the area he needed his support gone and got his result.

You need to place the support blocker where you want the support not to be, basically by targeting the overhangs. Check out the Ultimaker page for support blockers for some information on this.

Adjust the Minimum Support Area Setting

Some people have fixed their support blocker issues by adjusting a setting called the Minimum Support Area.

One user whose Cura support blocker did not work on his model fixed the issue by adjusting this setting under the support section of the Cura settings.