simple extrude problem - need help

[domer1322]

this should be simple, but I can't figure it out. I want to 3D model a roadway curb and gutter profile, and the curb goes up and down a hill, while curving horizontally. If I make a NURBS or 2D section profile for the L-shaped curb/gutter and extrude along a NURBS path, the sction gets twisted as it goes up and down. If the road were perfectly horizontal everything would be OK, but with the Z dimension in play, the section twists such that the gutter pan is longer horizontal. This is obvious if you exagerate the vertical dimen, but still introduces small errors when using with normal parameters. Any suggestions ?

[islandmon]

Segment the Path with the curves as separate +/- components. Then reassemble into the composite roadway. This isolates the problems.. just like in the real world of construction. Also, keep in mind that the profile requires sufficient vertices to compute the NURBS. Try adding or deleting a vertex mid span of the profile edges...magic things happen ; )