C4D Cafe: Sweepnurbs (plus 9.6 features) - C4D Cafe

I realize these are old tutorials and you probably discovered new solutions/methods, but I just want to point out, that in part 2 of this tutorial the weird "flipped" effect can be corrected without using a rail spline.

Part 2 of the video shows a rectangle that is sweeped along a helix. The helix spline is lying in the XY plane (as when you create it in the front view). In this case, when you sweep the rectangle along the helix and you turn banking off, you get those weird flipped distortions as shown in the video.

The video outlines using a rail spline as a solution. However, there's another way. Just simply create the helix in your top viewport, so it will lie on the XZ plane. Now create the rectangle in your front viewport (so it will lie on the XY plane). Now when you sweep, and uncheck banking, the rectangle will sweep around the helix without any distortion or curving, and it will spiral upwards on the Y axis.

You can now rotate the Sweep NURBS object 90 degrees so it will lie on the XY plane. This results in the rectangle swept around the helix on the XY plane without any distortion, but without requiring a rail spline.