Lofting Perfect Conoids

I want to make a Conoid. The basic loft commands uses the length of the curve to create ruling lines. Is there a way tore-parameterize the arc? I’m aware I can sweep or loft the ruling lines but this creates tiny imperfections

Ruling lines from normal loft

Side view where ruling lines are not parallel :frowning:

Ruling lines of conoid loft

Side view where ruling lines are parallel :slight_smile:

Difference between the two surfaces.

This is a conoid:
2020-08-15 00_54_54-Rhino 6 Commerciale - Perspective
and it have no parallel “ruling lines” , even if seen from any view.

Can you explain better?

Loft, as far as i know, make perfect conoids…
2020-08-15 00_57_25-Rhino 6 Commerciale - Perspective

If you want that side view result with parallel ruling lines, you can make it like this, with high enough divisions to be sure: (7.4 KB)