STL to STEP – How to Convert STL Files to STEP

STL files, or “stereolithography” files, are the standard format for 3D objects, especially for 3D printing. This file type creates an object by tessellating it (or turning it into a large number of smaller triangular shapes).

In contrast, STEP, which stands for “Standard for the Exchange of Product model data”, is a CAD file format commonly used for 3D models. STEP files represent objects that are transferrable from one CAD program to another without several intervening conversion steps.

The primary difference between the two is that STEP files are typically much easier to edit due to the STEP file type being designed specifically for CAD editing purposes.

In the following, we’ll take a look at two programs that can be used to convert STLs to STEPs.

A straightforward method of converting STL files to STEP files is to use Autodesk’s Fusion 360. To do this, first upload an STL file to Fusion 360.     

1. Navigate to the data panel and choose a subfolder to upload the files to.
2. Next, press the “Upload” button and press “Select files” to select the STL file you’d like to upload.
3. Next hit “Upload” and wait for the upload to finish.
4. Once that has finished, click on File -> Export.
5. From there, you can select a variety of file types to export to, including STEP.

A free alternative with which you can convert STL files to STEP files is FreeCAD, a downloadable CAD program. First, you need to bring your STL file into FreeCAD.

1. Hit File -> Open and select your STL file.
2. Once open, ensure that you have Tree View open by going to View -> Panels -> Tree View.
3. Ensure that “Part” is selected in the drop-down menu at the top middle of the screen.
4. With the file name selected in Tree View (CSG in the above image), go to Part -> Create shape from mesh, leave the sewing tolerance as 0.1 default, and select “Okay”.
5. Go to File -> Export and save your STEP file.

Feature image source: blog.bantamtools.com