[b]Swept protrusion[/b]

[Divedive]

I am trying to draw structure for a radiused staircase. The stair turns 50deg heads into a straight section then turns 90deg. I drew the slope for the stair using an intersection curve obtained from two extruded surfaces. When I try a swept protrusion, however; the channel corkscrews and ends up at an approximate 45deg angle from horizontal at the bottom. Is there any way I can correct this?

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