Primary and Secondary Regions
Introduction
When creating Turning features, it is important to understand how BobCAM analyzes the part geometry. After creating any Turning feature and selecting the corresponding geometry, you can click that feature name in the CAM tree to view the detected feature geometry. This can be used along with many of the Lathe Selection Manager options for proper feature creation.
Section Planes
When creating any Turning feature, BobCAM analyzes the profile of the selected geometry. The XZ plane is considered the zero degree starting point. BobCAM analyzes the part in different section planes. The First section plane start angle and the Interval angle between section planes options decide exactly how many section planes are used to analyze the part. For example, if First section plane start angle is set to zero degrees (the XZ plane) and Interval angle between section planes is set to 90 degrees, the profile of the part is analyzed in four different section planes.
Tip: The location of the section planes for a part can be viewed by selecting the Display Section Planes check box in the Selection Manager.
Primary and Secondary Regions
BobCAM checks the profile at each section plane and creates one profile to include the outer boundaries of all section planes. This outer boundary is called the primary region. The primary region creates the detected feature geometry. Any area that is not contiguous to the outer boundary (such as a groove) is called a secondary region.
The following image shows the primary region of this part. Notice that the groove is not included in the detected feature geometry. This feature geometry is used to create an turning feature which should not cut the groove. The groove is created with a separate feature and geometry selection.
The following image is used to show how the Primary region only option is used. If you select the geometry as shown, excluding the groove, with the Primary Region Only check box selected, a line connects the noncontiguous faces. This is another way to create a primary region.
