1. What is Specify Origin Curve?
In NX 12 ‘Specify Origin Curve’ option was introduced in the section group of the extrude command. For extrude or revolve when an ‘Open’ section is selected then origin curve will be either first curve or last curve. But in case of ‘Closed’ section there is no way to tell the origin of the curve. This option is helpful to specify the origin curve in the selected section and direction of the first curve of section is shown by a direction vector.
This option is useful in case Replace Feature mapping operation and it helps to organized mapping visually which results stable feature update after feature remapping.
2. How to Enable ‘Specify Origin Curve’?
In the NX 1969 MU (1953 Series), A new customer default was introduced as ‘Show Section Curve Flow Direction’. By default this customer default setting is disabled and it determines whether or not the curve flow direction and origin curve controls are available for section-based feature commands such as Extrude. (Flow direction and origin are always available for flow-sensitive features such as Swept.)
Go to File > Utilities > Customer Defaults > Modeling > General > General tab > Show Section Curve Flow Direction.
Enable it and Restart NX so that specify origin curve option will be available within section group of extrude command dialog.
Links: NX Documentation | NX CAD Tips & Tutorials