The tapered extrusion of a planar curve creates an incomplete surface

The lateral surface created from the script below in the attached zip file

_-SelId cc2c9135-1f2b-471b-bee5-cde5278d32d8 _-Enter _-ExtrudeCrvTapered _DraftAngle -45 _DeleteInput=No _Solid=No _Distance -20 _-Enter

creates also a small triangular brep instead of an extpected rectangular brep in the extrusion of the small side.

The resulting surface is not going all around the closed curve that generates the extrusion.

Extrude curve tapered (19.7 KB)

Yeah, that looks like a bug… Just extract the small triangular surface and replace it with a rectangular one for now is all I could suggest.

Yes, but it could be solved already in the “ExtrudeCrvTapered” script, to obtain from Rhino a surface already corrected.

In tapered extrusion of small protusions, Rhino 5 already creates come “approximations” to output a result that it seems ok at first glance.

Thanks for the hint anyway.

Yes, ExtrudeTapered is not reliable… If your curves are polylines like the one you posted and you can do the math, you can offset the curve to the outside (a little trig required to figure out the offset if it’s not 45°), lower it the needed height, then Loft the two curves…