Several people have wanted the Lathe operation to limit the angle of revolution to less than 360 degrees. This feature would work like Lathe but would allow sweeping the sketch though arbitrary angles while also sliding it along the axis of revolution to produce helical objects. Because NURBS can not exactly represent helical surfaces (the angular vs axial position is not perfectly linear) there should be adjustable number of segments to allow the user to minimize that distortion. When the axial displacement is 0.0 this will produce the same geometry as Lathe but with adjustable sweep angle. All surfaces created this way would be pure NURBS without doing boolean operations.