Unrollsrf / FlowAlongSrf not working as a workflow for stairs

Hi,

I am getting super frustrated, I need to build some solid sides to my stair (similar to the photo) and then put a hand rail along the top - as we know that rhino cannot control the sweep of a shape and constrain its banking I planned to use unrollsrf draw my geometry in 2d then flowalongsrf to get it curved! however It just distorts the geometry or sends it off in different directions - I swear i have done this in the past but I am stumped as to how to do this - does anyone have any ideas - I am tearing my hair out



TFR Balustrade.3dm (5.2 MB)

Hiu Thomas - if you are flowing from the flattened version to the 3d one, use UnrollSrfUV to get the flattened version since this will maintain the surface UVs in the result. Only untoll the curved surface, Rhino does not like the polysurface for some reason.

-Pascal

If I was modeling this I would

  1. Untrim the stairs
  2. Then use the surface to create the walls with a trim.
  3. Then sweep a top rail if wanted.

The railing surface will unroll more reliably if the original surface is made as a DevSurface.

why? stairlike option should be possible for sweep as well as for array crv