How to Attach a Sketch to a Face in FreeCAD

This article provides a step-by-step guide on how to map and attach sketches directly to the planar faces of existing geometry in FreeCAD rather than using the default global coordinate planes. You will learn the straightforward workflow for creating a new sketch on a selected face, the process for reorienting an existing sketch to a new surface, and best practices to prevent parametric model errors.

Creating a New Sketch on a Face

Attaching a new sketch to an existing face in the Part Design workbench is a native feature:

  1. Activate the Body: Ensure the Body containing your 3D model is active in the Model tree (its name will appear in bold text).
  2. Select the Face: In the 3D viewport, click on the planar face where you want to draw the new sketch. The selected face will highlight.
  3. Create the Sketch: Click the Create a new sketch icon in the Part Design toolbar (or select Part Design → Create sketch from the top menu).

FreeCAD automatically binds the sketch to the chosen face and opens the Sketcher interface aligned with that surface.

Attaching an Existing Sketch to a Face

If you have already created a sketch on a standard plane (XY, XZ, or YZ) and want to relocate it to a planar face:

  1. Select the Sketch: In the Model tree view, click on the sketch you wish to attach.
  2. Access Map Mode: In the Data tab of the Properties panel (located in the lower-left by default), expand the Attachment section.
  3. Open the Attachment Dialog: Click the value field next to Map Mode, then click the ellipsis (...) button that appears.
  4. Choose the Face: The 3D view enters reference selection mode. Click on the flat surface of your model where you want the sketch anchored. The dialog will list the face as "Reference 1."
  5. Select Attachment Method: Ensure the attachment mode is set to FlatFace.
  6. Adjust Position (Optional): If needed, use the Attachment Offset values (X, Y, Z, or rotation) to fine-tune the orientation of the sketch on the face.
  7. Confirm: Click OK. The sketch is now attached to the selected surface.

Best Practices and Datum Planes

While mapping sketches directly to faces is fast, changes made to earlier features in your model tree can alter internal face indexing—an issue known as the Topological Naming Problem.

For critical or complex parametric models, consider creating a Datum Plane attached to your geometry first, and then attaching your sketch to that Datum Plane. This provides a more resilient reference structure and prevents sketches from detaching or breaking if the underlying model is edited.