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Remesh with Gmsh

In one sentence: Re-mesh an existing mesh using the external Gmsh mesher to improve element quality, uniformity, and size control.

Overview

Workbench: Mesh
Menu: Mesh → Meshes → Remesh by Gmsh…
Command: Mesh_RemeshGmsh
Shortcut: none

Re-meshes an existing Mesh::Feature using the Gmsh mesher. Gmsh produces higher-quality elements than FreeCAD's built-in tessellator — better triangle shapes, more uniform sizes, and user-controlled element size bounds.

Intuition

When you import an STL with poor triangle quality (elongated or flat triangles) or when FreeCAD's built-in tessellator produces uneven element sizes, Gmsh can re-mesh the surface to produce triangles that are more regular and suitable for FEM analysis or high-quality rendering.

When to use it

  • The imported STL has poor triangle quality (very elongated or flat elements).
  • You need uniform element size across the mesh surface for FEA.
  • You want to reduce triangle count while maintaining surface accuracy.
  • Your FEA solver requires specific element size constraints.

When NOT to use it

  • Don't use it if Gmsh is not installed — Gmsh is an external dependency. Install it and set its path in preferences first.
  • Don't use it for quick 3-D printing prep — the built-in tessellator (From Part Shape) is faster and sufficient for most printing workflows.

Step-by-step

  1. Ensure Gmsh is installed and its path is set in Edit → Preferences → Mesh → Gmsh.
  2. Select the mesh in the model tree.
  3. Choose Mesh → Meshes → Remesh by Gmsh….
  4. Set the parameters (see below).
  5. Click OK. A new Mesh::Feature appears with the re-meshed result.

Parameters

Parameter Description
Max element size Largest triangle edge length (mm)
Min element size Smallest triangle edge length (mm)
Angle tolerance Curvature-driven size reduction at curved regions (°)

Common mistakes and pitfalls

Gmsh must be installed separately

Gmsh is not bundled with FreeCAD. Download it from gmsh.info and set its executable path in Edit → Preferences → Mesh → Gmsh path before using this tool.

Re-meshing changes triangle indices

Any references to specific triangle indices from the original mesh are invalidated after re-meshing.

See also