How to Create a Rotational Solid in FreeCAD

This article provides a step-by-step guide on creating a 3D rotational solid using the Revolution tool in FreeCAD's Part Design workbench. You will learn the requirements for drawing a compatible 2D sketch profile, how to initiate the revolution operation, and how to select the proper axis and angle parameters to generate your 3D model efficiently.

1. Set Up the Environment

  1. Open FreeCAD and create a new document.
  2. Switch to the Part Design workbench using the workbench dropdown menu.
  3. Click Create body in the Model tree or toolbar, then click Create sketch.
  4. Select a standard orientation plane (such as the XZ or YZ plane) and click OK.

2. Draw and Constrain the 2D Profile

A rotational solid requires a 2D cross-section that represents half of the final object.

  1. Using the geometry tools (lines, arcs, or polylines), draw the cross-sectional shape of the object.
  2. Crucial Rule: The entire sketch must remain completely on one side of the axis of rotation. Crossing over the rotation axis will cause self-intersecting geometry errors.
  3. Close the profile completely so there are no open endpoints.
  4. Apply geometric and dimensional constraints until the sketch turns fully constrained (typically indicated by turning green).
  5. Click Close to exit the Sketcher workbench.

3. Apply the Revolution Tool

  1. Ensure the sketch you just created is selected in the Model tree.
  2. Click the Revolution icon on the toolbar (or select Part Design > Apply a basic feature > Revolution from the top menu).
  3. The Task panel will open with revolution settings, and a 3D preview of your rotational solid will appear in the viewport.

4. Configure Parameters

  • Axis: Set the rotation axis. By default, it usually selects the sketch's vertical or horizontal axis. If your solid looks inverted or incorrect, choose the appropriate sketch axis or select a custom reference datum line.
  • Angle: Set the degree of rotation. Enter 360.0° for a complete, closed circular solid, or a smaller angle (such as 180.0°) for a partial solid.
  • Symmetric to plane: Check this option if you want the angle of revolution to distribute evenly on both sides of your sketch plane.
  • Reversed: Toggle this to revolve the geometry in the opposite direction.

5. Finalize the Solid

Once the preview matches your desired shape, click OK in the Task panel. Your sketch is now converted into a fully parametric rotational solid, ready for further modeling operations like filleting, chamfering, or pocketing.