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Sketch on Surface

In one sentence: Maps a flat Sketcher sketch onto a curved surface — wrapping the XY plane onto the target face's UV parametric space.

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 → Sketch on Surface
Command: SoS

The sketch's XY extent is mapped to the face's full UV range (0–1 in both directions). The result updates if the underlying face changes.

Common uses

  • Engraving lettering or logos onto a curved part
  • Projecting a 2-D pattern onto a free-form surface
  • Creating trim curves that follow a surface's shape

Common mistakes and pitfalls

Sketch must lie flat in XY plane

Any Z offset in the sketch will be ignored. All geometry must be at Z = 0.

UV distortion is inherent

A non-uniform UV parametrisation means equal XY distances in the sketch map to unequal arc lengths on the surface. Accept this distortion or use Curve on Surface to manually trace the face's geometry.

See also