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Gordon Surface

In one sentence: Creates a surface that exactly interpolates a network of crossing curves — every U-direction and V-direction curve lies on the resulting surface.

Third-party addon — installation required

The Curves workbench is not included in FreeCAD. Install it via Tools → Addon Manager → search "Curves" → Install and restart FreeCAD.

Overview

Workbench: Curves
Menu: Surfaces → Gordon Surface
Command: gordon

A Gordon surface is the classic method for surfacing free-form shapes defined by a network of cross-section and longitudinal guide curves. Every curve in the network lies exactly on the surface.

Input requirements

  • At least 2 U-direction curves and 2 V-direction curves
  • Each U curve must intersect each V curve exactly once
  • The intersection points must be geometric (within tolerance)
  • Use Gordon Profile curves for best results
  1. Create U-family curves (cross-sections) using Gordon Profile.
  2. Create V-family curves (longitudinal guides) using Gordon Profile.
  3. Select all U curves, then all V curves.
  4. Choose Surfaces → Gordon Surface.

Common mistakes and pitfalls

Curves do not intersect

If the curves do not physically cross within the geometric tolerance, the tool fails. Use Extend Curve or adjust control points so curves cross exactly.

See also