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To create a GD&T Symmetry item

Symmetry determines whether two planes have the same orientation and location on each side of a specified datum plane.

To create a GD&T Symmetry item:

  1. Open a Geometric group in the inspection sequence.
  2. Click Geometry tab > GD&T panel > Location > Symmetry.
  3. Enter a Name for the item.
  4. To exclude this item from the report, deselect the Output in report check box.
  5. To restrict the Feature 2 list to planes whose normals are close to symmetrical with the Feature 1 item:
    1. Select the Use angular tolerance to filter the available features check box.
    2. Enter the maximum angle by which the normals of Feature 2 items can vary from the nominal in the Angular tolerance box.

    If you do not want to apply any filtering to the Feature 2 list, deselect the Use angular tolerance to filter the available features check box.

  6. To record extra information about the item, type it in the Comment box.
  7. Click Next. The Symmetry Definition dialog is displayed.
  8. Choose the datum plane around which you want to check for symmetry. Select:
    • Calculate datum from nominal planes to calculate the datum plane from the nominals of Feature 1 and Feature 2.
    • Use datum and select an entry in the list to specify the plane you want to use as the datum.

    The diagram at the bottom-right of the dialog illustrates the shape of the tolerance zone.

  9. In the Feature 1 and Feature 2 lists, select the planes whose symmetry you want to report. Click to select an item from the CAD view using the mouse.
  10. Enter the width of the tolerance zone in the Tolerance box. The control frame at the top of the dialog summarizes the tolerancing requirements.
  11. Click Next. The results of the GD&T calculation are displayed in the Result Preview dialog. If the result is:
    • Accepted, the measurement is in-tolerance.
    • Out of Tolerance, the measurement is out-of-tolerance.
    • Not Calculated, the measurement cannot be calculated because one or more of the selected features or datums is unmeasured.
  12. Click Finish to create the item and save the results, or click Back to change the item definition.

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