This will wrap the curve onto the cylindrical (or whatever) surface and make a true cut normal to the surface. Exit the sketch, select it, and use Feature > Wrap, with the Deboss option selected. You can create a curve apparently accurately representing the outline of an endmill cut by offsetting both ways a construction spline or series of construction elements (controlling the ends of a spline with tangency to line segments is useful) and closing the ends with an arc tangent to both curves. Create a plane tangent to the surface of the cylinder and create a CLOSED sketch on it. The tutorial is definitely worth downloading and looking at, but the core of the technique that he (and I) used is the Feature Wrap function. It's a VERY complex creation he's built - perhaps more complex than absolutely necessary, but it's hard for me to say.

Formatting link One of his tutorials is for a cam that apparently represents a sine wave accurately.