Your design calls for a sweep to be cut along a spline path on the surface of a cylinder. The finished feature is shown below.
If you have ever tried to create this type of feature, the process is pretty simple until you get to the creation of the sweep itself. You find you cannot cut the ends of the sweep out completely because the path is ending at the part edge and since the sketch is square to the path it leaves material at the ends of the cut.
You probably have tried to fix this problem by making the part longer, create the cut and then trim it off or maybe you tried to trim off the remaining material at the ends of each cut. These methods take time and may be inaccurate.
Inventor Copy Object tool can make this job a snap. One of the many operations you can do with this tool is to copy a surface for a part to use in the creation of other features. The tool is located on the Modify Panel.

Configure the Copy Object tool as shown below and select the outside of the cylinder as the face to copy.
You now have a surface on top of the existing cylinder. Next, select the Extend (Surface) tool located in the drop down tools of Surface Panel.
Select one end of the new surface and extend it to give you the added length you need to get a complete cut with our sweep. Repeat the command and extend the other end as well. The easiest wayto extend the surface is to select the edge of the surface and drag the arrow.
When creating the 3D sketch, you will use the new surface as the face to project the required spline onto. The resultant 3D path is well beyond the ends of the cylinder giving you a clean finished cut path when you do your sweep feature.
After you turn off the visibility of the surface, you are finished and ready to explore the other uses of the Copy Object tool.