Part Fuse

From FreeCAD Documentation

Part Fuse

Menu location
Part → Boolean → Union
Default shortcut
Introduced in version
See also
Part Boolean, Part Cut, Part Common


The Part Fuse tool fuses (unites) selected Part objects into one. This operation is fully parametric and the components can be modified and the result recomputed.

Note: This command is an automated form of the Boolean operation.


  1. Select two or more shapes
  2. There are several ways to invoke the command:
    • Press the Part Fuse button in the Part tools toolbar
    • Use the Part → Boolean → Union entry in the Part menu

Supported inputs

Input objects must be OpenCASCADE shapes. Examples: stuff made with Part, PartDesign, Sketcher workbenches. Not meshes (unless those were converted to shapes) - for meshes, there are specific Boolean tools in MeshDesign workbench.

  • Solid + Solid: the result is a solid that occupies all the volume covered by the inputs
  • Shell + Shell, Shell + Face, Face + Face: the result is a shell. Where faces intersect, they are split. Shells can be non-manifold. After fusion, faces can be united by Refining the result.
  • Wire + Wire, Edge + Wire, Edge + Edge: the result is a wire. Edges are split where they intersect.

Compounds are supported; however, it is assumed that shapes packed into a compound do not touch or intersect. If they actually do, Fusion will likely fail, or produce an incorrect result.


Items can be added and removed from a fusion, by dragging them in or out of the fusion feature in the tree view with the mouse. To drag items out of a fusion you have to drop them onto the document node (the filename) of your model. A manual recompute (press F5 key or click on the Refresh/Recompute icon) is required to see the results.

After this operation is complete, it may be necessary to clean up the shape with RefineShape.