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To construct a circle where a circular feature and a plane intersect

Use the Circle: Circular Feature & Plane item to create the circle at the intersection of a plane with a 3D circular item, such as a cylinder or a cone.

Note: If you are using a cylinder or a cone, the reference plane must be perpendicular to the item's main axis to create a true circle. If the plane is not perpendicular, a best fit is performed and the error between the true circle and the fitted circle is reported.

To create a Circle: Circular Feature & Plane item:

  1. Open a Geometric group in the Sequence Tree.
  2. Click Geometry tab > Features tab > Circles > Circle: Circular Feature & Plane.

The Circle: Circular Feature & Plane dialog contains the following areas:

Name — Enter a name for the item. The name is used in the inspection sequence, in the Report and Info tabs, and when referencing the item in other items.

Use nominals — Select this check box to enter or change the item nominals, and to compare the item measurements to their nominal values. Deselect this check box to disable comparisons with the item nominals.

When this check box is selected, an in-tolerance or out-of-tolerance indicator is displayed on the measured item's icon in the inspection sequence; the border of the item label is coloured to indicate whether the measurements are within tolerance; and the tolerance, nominal, deviation, and error values of the item are shown in the report.

When this check box is deselected, the Nominal boxes are disabled, no tolerance indicators are displayed and no tolerance, nominal, deviation, and error values are shown in the report for this item.

Note: To load the nominals from the CAD model, click and select From CAD Entity. To replace the nominals with the item's measurements in the current Measure, click the button and select From Active Measure.

Visible — Select this check box to display the item in the CAD view.

Output in report — Select this check box to include the item in the report.

Coordinate system — Select the alignment relative to which the item's measurements are to be reported.

To specify the alignment during the inspection, select <Active Alignment>. You can then select the alignment from the Active alignment list, or by adding an Active Alignment item to the inspection sequence.

Reference plane — Select the cut plane on which you want to construct the circle.

Cut entity — Select the item from which you want to construct the circle.

Centre — Enter the nominal and tolerances for the position of the circle centre.

Diameter — Enter the nominal and tolerances for the Radius or Diameter of the circle.

Circularity — Enter the Maximum acceptable difference between the points with greatest positive deviation and greatest negative deviation from the best-fit circle. If the difference between the greatest positive deviation and greatest negative deviation exceeds the Maximum value, the circularity is out-of-tolerance.

To measure circularity, PowerInspect calculates the best-fit circle, C1, through the points. It then runs two concentric circles through the points furthest from the new circle in each direction, shown as C2 and C3:

The Circularity value is the difference between the radii of C2 and C3.

Note: This value is used only when the reference plane is not perpendicular to the cut entity's main axis.

Click OK to close the dialog and save your changes.

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