Orient curve to perpendicular to surface

when orient a profile to sweep along multiple lines, how to make the orientation perpendicular to the surface Q_how to orient profile perpendicular to surface.gh (26.6 KB) .

orient profile perpendicular to surface_2021Jan7aa.gh (34.6 KB)

P.S. Had I spent a few more seconds studying the model, I would have noticed that all your effort to manipulate the ‘A’ (Source) input to Orient wasn’t necessary. The default ‘World XY’ works fine and requires one less rotate component in the white group I added.

orient profile perpendicular to surface_2021Jan7b.gh (27.4 KB)

P.P.S. Or maybe not… The section profile is not actually at the origin, as expected. :man_facepalming:

Yet another P.S. In top view, the section curve appeared to be at the origin but in fact was ~-550 units below it for some very odd reason? So I moved it up to Z = 0.

orient profile perpendicular to surface_2021Jan7c.gh (32.1 KB)