Trim the Curve with Planes
- 
                From the HyperGraph 3D toolbar, click the Datum
                    Planes icon, 
.
             - Click Add under the Datum list.
 - Set the plane type to Clipping plane.
 - Click Reverse under the list of plane types to view the opposing side of the curve, if desired.
 - Select the Position tab.
 - 
                Under Method:, set the orientation method: 
                
- Vertical along the Z axis 

 - Horizontal along the X axis 

 - Horizontal along the Y axis 

 - Three points 

 
Click two points on the curve to define the Orientation points.
 - Vertical along the Z axis 
 - 
                If you selected Three points, click three points on the curve to define the
                    Orientation points.
                The plane passes between these points along the Method axis.
 - Drag the slider, click a point, or enter a location for one side of the trimmed area.
 - Repeat steps 1-8 for the other size of the trimmed area.