Hi Rudl, so looking at your shape I think I understand what you want.

First create a point at the pivot origin point (use Draw curve > More > Point), and then hide the big sphere piece to get it temporarily out of the way.

Then run the View > CPlane command, and place the origin of the cplane on to that point - it will align the z axis of the cplane perpendicular to that planar end cap surface and then right-click to accept the default rotation placement around that z axis to set the cplane, the screen should now look like this:



Now go to the Top view - you can't use the 3D view for this next step because it ends up using the wrong plane if you snap on to a point, I think this may be a bug that I need to look into (or is it possible those end pieces are not quite exactly planar?). But if you use the Top view it will work fine.

So go to the top view and draw a circle with the center at that point, and the radius of it going through the tip of the shape, like this:



That will create something that looks like this in the 3D view:



So that circle traces out the path that I think you want to pivot the shape by. Unhide the sphere and then select the sphere and the circle and run Construct > Curve > Isect, which will generate a point where the circle intersects the sphere, like this:



That point can now be snapped on to - duplicate the edge curves as regular curve objects by selecting them and doing a ctrl+C and ctrl+V, and then you can go back to the Top view and use the Transform > Rotate command to rotate - pick the rotation origin at that first point that was created, and the first reference point at the tip of the shape and the last reference point at the circle/sphere intersection point.

Then to restore the cplane to default, do a right-click on the View > CPlane button.

Hope this helps!

- Michael