Hi niko - what is it that you are trying to do with your curves there, are you trying to sweep the short one with the long ones as rails?

Your base short curve is not planar - it is kind of squiggling around in 3D - you may want to flatten it to be planar in order to get some more predictable overall behavior.

To do that you can use the edit frame in the Top View with the "flat" snap, like this:



After you have done that, you can just directly sweep your curve along the rails without doing any extra manual orientation or placement steps - Sweep already incorporates a kind of automatic orientation mechanism inside of it. So just select it and run sweep:



Is that what you are trying to do here?

When the sweep profile is located a distance away from the rails (outside of the bounding box around the rails), then there is an automatic positioning mechanism that will move the profile to the rails for you so you don't need to do any manual positioning stuff in that case.


After you have flattened your curve, it is possible to use the edit frame to position it in this case, but because your rail endpoints are not on any of the world axis planes you will need to use the frame in 2 different views instead of being able to do it all in just one view.


So from the top view you would do this:



Then switch to a side view to adjust the elevation, like this:





But again, it's just easier to use the orientation stuff that is built directly into sweep and not even bother to move the profile over at all.

- Michael