Can Cura Open 3MF Files? (What Does It Do?)

When we think of the file types used in 3D printing, the STL files, which are responsible for containing the 3D model information that we can use in CAD and slicer software, and the G-code files, which essentially is a list of commands that the 3D printer uses to conduct the 3D printing process, are the first ones that come to mind.

On the other hand, while not as common, it’s also possible to find many other file types used in 3D printing alongside the standard STL and G-code formats, meaning that you may eventually stumble upon one such file in your 3D printing journey and end up having to use it.

In today’s article, we will talk about one such file format used in 3D printing that you may not be familiar with, known as 3MF, and whether Cura, the most used slicer on the market right now, is compatible with this file format, which will be a handy piece of information to keep in mind while downloading files related to 3D printing. 

So, can Cura open 3MF files?

Cura can indeed open 3MF files that contain 3D models and, in fact, actively utilizes the 3MF format as the default filetype for its project files, which automatically loads extra information such as the print settings, the filament type, the nozzle size, and the printer model.

In the upcoming sections, we will dive deeper into the compatibility between Cura and 3MF files, find out what the purpose of a 3MF file is, go through the process of troubleshooting for the scenario where Cura cannot open a 3MF file, and finally, discuss the differences between 3MF and STL files.

Can Cura Open 3MF Files?

Ensuring that the slicer software you intend to use can support all the file types that you will need on your 3D printing journey is essential, as having to switch to a different slicer later would be pretty inconvenient with the learning curve involved.

Fortunately, Cura is fully capable of both reading and writing 3MF files out of the box without the need for any external plugins (just like STL files), meaning that you can feel free to download 3D models that have the 3MF file format and slice them in Cura.

On the other hand, one thing to be aware of is the fact that even though 3MF files can also contain slicer-specific settings (such as in the case of Cura project files), these settings can’t be transferred across different slicer software.

For instance, if you have created a 3MF file in PrusaSlicer that contains the custom settings you have adjusted alongside the 3D model data, importing this file in Cura will only allow Cura to read the 3D model data, but not the custom settings, as these are not universal between different slicer software.

What Is the Purpose of 3MF Files?

Unlike the STL file type that contains 3D model data and the G-code file type that the 3D printer utilizes to print, which make up the majority of the files in 3D printing, 3MF files are slightly rarer to come across in most cases.

3MF files have the exact same purpose as STL files in the context of 3D printing, which is to carry 3D model data that can be modified with CAD software, such as Meshmixer, for design purposes, and turned into G-code with slicer software, such as Cura, for the 3D printing process.

Aside from being a file format that carries 3D model information, the 3MF file type is also what Cura uses to create project files, which, alongside 3D model data, also contain the active modifications to print settings, material type, nozzle size, and more.

As a result, by creating a 3MF project file in Cura, it’s entirely possible to save a 3D model together with all the explicitly tuned settings for the purposes of printing that particular 3D model, which allows you to essentially store files that are fully ready to print without any extra work.

Cura Not Opening 3MF Files – What to Do?

Even though Cura should technically support the opening of 3MF files, we have noticed some reports from the users in the community about scenarios where Cura throws an error when attempting to import a 3MF file, which should not happen.

The primary factor that can prevent Cura from opening a 3MF file is the 3mfreader (and 3mfwriter) plugins being deleted or disabled, which are the pre-installed plugins that give Cura support for reading and writing 3MF files.

To find out whether the 3mfreader (and 3mfwriter) plugins are correctly installed, you can follow the step-by-step guide below:

  1. Navigate to the Cura installation folder. For instance, the default path in Windows would be C:\Program Files\Ultimaker Cura <version_number>.
  2. For Cura 4.x.x, directly navigate to the plugins folder. On the other hand, for Cura 5.x.x, you will find the plugins folder by following the path of share -> cura folders.
  3. Ensure that the 3MFReader and 3MFWriters are present. If the folders aren’t present, reinstall Cura.
  4. Open Cura, and click the Marketplace button on the top-left corner.
  5. Click the Installed tab on the Marketplace dialog.
  6. Scroll down and ensure that the 3MF Reader plugin (under the Bundled Plugins section) is enabled.

If you are still unable to open the 3MF file that you have at hand with Cura, we recommend going through the steps below, which will allow you to find out whether the file is corrupted, or a problem exists within your Cura installation:

  1. Try to open another 3MF file. In some cases, the 3MF file itself can be corrupted, which will prevent Cura from being able to read it, and in the case that you can open a different 3MF file with any issues, this becomes highly likely.
  2. Try to open the 3MF file you cannot open on another computer. Another way to find out whether the 3MF file itself or your installation Cura is the problem is to open the 3MF file on another computer. If the file doesn’t open, there’s a good chance it’s corrupted; else, there is most likely an issue with your Cura installation.

If you are still unable to pinpoint the problem after these steps, we recommend uploading your Cura log file to the Cura section of Ultimaker community forums alongside an explanation of the issue you’re facing, where community members and Cura developers may be able to help you.

What Are the Differences Between 3MF and STL Files?

While both STL and 3MF files are valid file types for 3D models, meaning that you can use either with most modern slicer software, there are differences in how these two file types operate, which can create a scenario where you might need to make a choice between the two.

In a nutshell, while STL files only contain data about the surface geometry of the 3D model, with no support for information such as color, material, or units, 3MF files are capable of carrying all the vital information required for the 3D printing process, even including custom slicer configuration.

Alongside carrying a much more extensive range of information, 3MF files are also considerably smaller in size compared to STL files, and even though the difference may not have too much of an impact on a single, standard model for 3D printing, in situations where large files need to be transferred in bulk, it can come in very handy.

Wrapping Up

Even though you won’t stumble upon 3MF files as much as you do with STL files, it’s still a good idea to ensure that the slicer you’re using is capable of opening 3MF files in case the occasion arises for it.

Considering that 3MF is the default file format for Cura’s project files, Cura is indeed capable of opening 3MF files whether they are project files (which allow you to either open the file as a 3D model or a whole project) or standard 3D model files, similar to the STL files we are used to seeing.

With the many advantages that it brings over the STL file type, and considering that Cura’s project files also use this file format, there is no question that you will be seeing more and more 3MF files in the future of 3D printing and significantly more so if you use Cura.

Happy printing!