Creating Datum on Non-Canonical Surfaces

You can create a datum on non-canonical surface (complex surface or prismatic surface) with the tolerancing advisor.

Before you begin: Open an existing 3D shape.
See Also
About Datum and Datum Target Elements
  1. From the Annotation section of the action bar, click Tolerancing Advisor .

    The Semantic Tolerancing Advisor dialog box appears.

  2. Multi-select the three spheres as shown:





    The Semantic Tolerancing Advisor dialog box is updated according to the selected surfaces.

    As you can notice, there is no Semantic Datum command in the dialog box because it is not possible to create a datum on non-canonical surfaces, compare with Creating Semantic Datum and Datum Targets.

    To do this, you have to redefined the geometric surface to consider the non-canonical surfaces as an unique surface.

  3. Select One Surface in the Geometry feature type drop-down list in the Semantic Tolerancing Advisor dialog box.
    Semantic Datum command is available.
  4. Click Semantic Datum .
    The Datum feature dialog box appears.

    To define the unique surface representing the non-canonical surfaces, you have to select a plane which represents the orientation of this surface.

  5. Select the Definition Element box in the Datum Direction section, and select the surface as shown on the Support component.



    In the Datum feature dialog box, the Definition Element box contains the representing surface.

  6. Click OK.
    The datum is created.
  7. Click Close in the Semantic Tolerancing Advisor dialog box.