Sweep1 - keep orientation to curve?

Rhino Rhino for Windows
1

Hi,

How do I do a simple sweep such that the profile keeps an orientation to the curve. Or, in other words, if thought of as a pipe, how to keep the cross-section so that if water was flowing through it, it wouldn’t get restricted? I feel like ive tried all options and will happily feel stupid with an answer:)

sweep-test
sweep-test.JPG547×938 22.7 KB

sweep test.3dm (25.8 KB)

2

what cause this not to work is that you have the upper profile curve twisted further than the spiral would flow.
either you delete one profile and use sweep1 or you introduce a 2nd rail curve with spiral and option around curve which needs exact 1.6 turns - this intersects the spiral at the perpendicular edge. then use sweep2.

sweep test.3dm (92.4 KB)

3

Thank you:)

Can I ask a few more potentially silly questions?

  1. how do you position/create the second rail?
  2. is this possible with just one rail but several profiles to control a change in width over the length of the curve?

Thank you!

4

spiral and helix have an option called around curve, the radius does not matter much since it only needs this 2nd rail to orient the profile properly. the amount of extra twist i just estimated by looking in from above, then made a binary search to match it.

you can try with a lot of profile curves if they stay in close range but i would not do that because thats rather imprecise. and the necessity of doing this also depends on how you derived the upper profile curve and also on how you can place the further profile curves. if you have like in this case a further twist then manually placing them precise might be quite a challenge even if you would use commands like OrientOnCrv since the extra twist would not be possible like that.