Converting 3D Printable STL Files Into STEP for CAD

Got some STL 3D printing files you want to convert to the STEP format for CAD software? We'll show you how to do it.

Unlike traditional CAD software, 3D modeling tools like Blender and Maya aren’t designed to produce files for manufacturing. Simple plugins allow you to export STL files from software like this, but exporting STEP files isn’t possible without a few additional steps.This article will take you through the process of converting any STL file into a STEP file, with steps to ensure that the end result is error-free.

Step 1: Exporting an STL From Blender

Blender can export STL files natively, making it ideal for those who want to create models for 3D printing and CNC machining. Go to File > Export > Export as STL and choose the file location and name you would like to use. You can choose to export the Selection Only if you want to isolate part of your Blender project.

Step 2: Importing the STL Into FreeCAD

Next, it’s time to import your new STL file into FreeCAD, which is one of the best CAD programs. Go to File > Import and choose the STL file you created in the previous step. A mesh that resembles your 3D model will appear on the screen, giving you the chance to check for errors before continuing.

Step 3: Repairing the Model’s Mesh in FreeCAD

Some mesh problems are visible when you first load your file, but others won’t be so obvious. FreeCAD comes equipped with a set of analysis tools that make it easy to ensure that your mesh model is manifold and free from errors. Start by selecting the Workbench dropdown menu and choosing Mesh Design.

Go to Meshes > Analyze > Evaluate and repair mesh to open the mesh repair tool. You will see an All above tests together option at the bottom of the list. Select Analyze and wait for the process to complete before hitting the Repair button. You may need to go through this process more than once to fully repair your model, but there is a chance your model doesn’t need any repairs.

Step 4: Converting the STL Mesh Into a Shape in FreeCAD

An STL is only an outer mesh, while a STEP file is a solid 3D object. This means that you need to convert your STL mesh into a solid in FreeCAD, but this can only be done once the mesh has become a shape. Start by going to the Part workbench, followed by opening the Part dropdown menu and selecting Create shape from mesh. A pop-up will appear so that you can choose an Overlap Tolerance; leave this at 0.10 and hit OK.

It will take some time to create your shape if the mesh you are using is complicated.

Step 5: Converting the Shape Into a Solid in FreeCAD

With your shape ready to go, you can create the solid you need for your STEP file. Select the shape you just created in the Model panel, followed by going to Part > Convert to solid. This will create a new item in the Model panel with (Solid) next to its name.

Step 6: Exporting the Solid as a CAD-Compatible STEP File

It’s finally time to create your STEP file! Go to File > Export and choose the location for the STEP file you are making. Select the Save as type drop-down and scroll through the list to find STEP with color before hitting the Save button.

Using a Converted STL as a STEP File

STEP files can be used for a variety of CAD applications. Many people don’t have their own CNC machine or 3D printer, but you can find services online that can turn your files into real objects. The methods discussed in this article will work for any STL file, though complex and detailed models will take more time.