Convert a Solid to a Mesh in FreeCAD

Converting a solid shape into a polygon mesh in FreeCAD allows you to prepare parametric 3D CAD models for 3D printing, rendering, or use in external polygon-modeling software. This guide covers the straightforward process of transforming solid bodies created in the Part or Part Design workbenches into tessellated meshes using FreeCAD's dedicated Mesh Design workbench, including tuning the mesh resolution and exporting the final result.

1. Switch to the Mesh Design Workbench

Open your FreeCAD document containing the solid object you wish to convert. Navigate to the workbench selector dropdown menu located at the top of the interface and select Mesh Design.

2. Select the Solid Object

In the Model tree view on the left side of the screen, click on the solid body, part, or feature you want to convert to highlight it.

3. Open the "Create Mesh from Shape" Tool

With the solid selected, go to the top application menu and click Meshes, then select Create mesh from shape... (alternatively, click the corresponding yellow icon on the toolbar). This will open the Tessellation panel in the Tasks tab on the left.

4. Choose a Meshing Algorithm and Settings

The Tessellation panel offers several meshing engines:

  • Standard: Uses the internal OpenCASCADE mesher. It relies on Surface deviation to determine accuracy. Lowering the surface deviation value results in a denser, smoother mesh with more polygons.
  • Mefisto: Generates mostly equilateral triangular faces. You set the Maximum edge length to control the triangle size.
  • Netgen: A robust algorithmic mesher that provides advanced controls for fineness (ranging from Very Coarse to Very Fine) and custom parameters for complex curved surfaces.

For most standard conversion tasks, the Standard mesher with a surface deviation between 0.1 mm and 0.01 mm provides a good balance between file size and surface smoothness.

5. Generate the Mesh

Click OK to process the conversion. FreeCAD creates a new polygon mesh object in the Model tree, typically named with the original object's name followed by (Meshed). The original solid remains intact and unchanged. You can hide the original solid by selecting it and pressing the Spacebar to inspect the generated mesh.

6. Export the Mesh (Optional)

To use the mesh outside of FreeCAD:

  1. Select the newly created mesh object in the Model tree.
  2. Go to File > Export.
  3. Select your desired mesh format from the dropdown menu, such as STL mesh (.stl) or Wavefront OBJ (.obj), specify the save location, and click Save.