How to Create an Ellipse in FreeCAD Sketch

Creating an ellipse inside a FreeCAD sketch is a straightforward process using the Sketcher workbench's dedicated conic tools. This guide explains how to locate the ellipse tool, place an ellipse by defining its center point and axes, and apply the appropriate geometric and dimensional constraints to ensure your sketch is fully defined and ready for 3D modeling operations.

1. Open or Create a Sketch

Open your FreeCAD model and switch to either the Part Design workbench or the Sketcher workbench. Create a new sketch on your chosen reference plane (XY, XZ, or YZ), or double-click an existing sketch in the tree view to enter edit mode.

2. Select the Ellipse Tool

Locate the conic section tools in the Sketcher toolbar. Click the drop-down arrow next to the conic shapes icon and select Create an ellipse by center, radius and point (or select Sketch → Sketcher geometries → Create ellipse from the top menu).

3. Draw the Ellipse in the Viewport

Drawing the ellipse requires three mouse clicks:

  1. Set the Center: Left-click in the sketch area to establish the center point of the ellipse.
  2. Define the Major Axis: Move the cursor outward to define the direction and length of the first (major) radius, then left-click to set the endpoint.
  3. Define the Minor Axis: Move the cursor perpendicular to the first axis to stretch out the second (minor) radius, then left-click to finalize the shape.

Right-click once or press the Esc key to exit the ellipse creation tool.

4. Fully Constrain the Ellipse

FreeCAD automatically generates internal construction lines for the ellipse representing its major and minor axes. To fully constrain the shape:

  • Constrain Position: Select the center point of the ellipse and apply a Coincident constraint to attach it to the sketch origin or another reference vertex.
  • Constrain Orientation: Select the construction line representing the major axis and apply a Horizontal constraint, Vertical constraint, or an Angle constraint to fix its orientation.
  • Constrain Dimensions: Apply a Distance constraint or a Radius/Diameter constraint to the major and minor axis construction lines to set precise dimensional values.