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Section by Plane

In one sentence: Create a cross-section wire at the intersection of a plane with the mesh — producing a set of line segments, not a trimmed mesh.

Overview

Workbench: Mesh
Menu: Mesh → Meshes → Cutting → Section by Plane
Command: Mesh_SectionByPlane
Shortcut: none

Creates a cross-section wire (a set of line segments) at the intersection of a user-defined plane with the mesh. The mesh is not modified. The result is a Part::Feature wire at the cut plane.

Intuition

Section by Plane is the read-only version of Trim by Plane: it computes the intersection profile without cutting away anything. Use it to extract a 2-D cross-section for measurement, reference in Sketcher, or CNC toolpath generation.

When to use it

  • Extracting a 2-D profile from a scan mesh at a specific height.
  • Creating a contour wire for CNC machining or reverse-engineering.
  • Measuring the cross-sectional shape of an imported mesh.
  • Providing an external geometry reference in Sketcher.

When NOT to use it

  • Don't use it if you want to trim the mesh — use Trim by Plane instead.

Step-by-step

  1. Select the mesh.
  2. Choose Mesh → Meshes → Cutting → Section by Plane.
  3. Pick three points to define the cutting plane, or use the task panel to set a point and normal vector.
  4. A Part::Feature wire appears at the intersection.

Common mistakes and pitfalls

Result is a wire, not a face or solid

The output is a set of line segments — not a face or solid. To use it as a sketch profile, switch to Sketcher and import the wire as external geometry.

Section through a hole or gap produces discontinuous segments

If the mesh has holes at the cut plane, the resulting wire will be discontinuous (open loops). Fill holes first with Evaluate and Repair.

See also