How to Create an Intersecting Body in FreeCAD

Creating an intersecting body feature in FreeCAD allows you to retain only the overlapping volume shared by two or more solid objects. This tutorial covers the exact steps to perform an intersection (often called a "Common" operation) using both the Part Design Workbench for parametric, feature-based modeling and the Part Workbench for direct solid modeling.

Method 1: Using the Part Design Workbench (Parametric)

The Part Design Workbench uses a Boolean feature to intersect two distinct bodies within the same document.

  1. Create the First Body:
    • Switch to the Part Design Workbench.
    • Click Create body, then Create sketch.
    • Draw your profile, close the sketch, and use Pad to turn it into a 3D solid.
  2. Create the Second Body:
    • Click Create body again to start an entirely separate body.
    • Create a sketch positioned so that it overlaps the first solid.
    • Pad or revolve the sketch so the two bodies physically collide and occupy the same space.
  3. Apply the Boolean Feature:
    • Double-click the body you wish to keep as the primary container (making it active).
    • Click the Boolean operation icon in the toolbar (blue and red overlapping shapes).
    • In the Tasks panel on the left, select Common from the dropdown menu (Common produces the intersection).
    • Click the Add body button and select the second body from the 3D view or the Model tree.
    • Click OK to apply. The resulting feature will display only the volume where both bodies overlapped.

Method 2: Using the Part Workbench (Direct Solid Modeling)

The Part Workbench offers a faster, non-container-based approach suitable for primitive shapes or independent solids.

  1. Switch Workbenches: Select the Part Workbench from the workbench dropdown list.
  2. Generate Solids: Create two intersecting shapes (such as boxes, cylinders, or extrusions).
  3. Select Both Shapes: Hold Ctrl (or Cmd on macOS) and click on both objects in the Model tree or directly in the 3D view.
  4. Execute the Intersection: Click the Intersection tool icon on the toolbar (depicted by two overlapping blue circles with the shared area highlighted).
  5. View Result: FreeCAD will generate a new object named Common in your tree view, hiding the original shapes and displaying only the shared intersection volume.