How to Constrain Point to Line Midpoint in FreeCAD

Constraining a point to the exact midpoint of a line is a fundamental operation in FreeCAD's Sketcher workbench. While older versions relied exclusively on a three-point symmetry constraint, modern versions of FreeCAD (v0.21 and newer) feature a dedicated workflow to snap a point directly to a line's center. This guide outlines the fastest methods to lock any point to the midpoint of a line segment.

Method 1: Direct Midpoint Constraint (FreeCAD 0.21 and 1.0+)

Recent versions of FreeCAD allow you to constrain a point to a line segment's center using just two clicks.

1. Open your sketch in the Sketcher Workbench.
2. Click the point you wish to center.
3. Click the line segment (the line itself, not its endpoints).
4. Click the Constrain symmetrical tool in the toolbar (or press the S shortcut key).
5. The point will automatically lock to the exact geometric midpoint of the line.

Method 2: Three-Point Symmetry Constraint (Universal Method)

If you are using an older version of FreeCAD or need to center a point between two independent vertices, use the classic three-point selection sequence.

1. Select the first endpoint of the line segment.
2. Select the second endpoint of the line segment.
3. Select the target point you want located at the midpoint.
4. Click the Constrain symmetrical tool or press the S shortcut.

Note: Selection order is critical for this method. The target point that will move to the center must always be selected last.

Verifying the Constraint

Once applied, FreeCAD will display a symmetry constraint icon near the point. You can verify the constraint by clicking and dragging one of the line's endpoints; the constrained point will dynamically adjust its position to remain precisely centered along the line segment.