How to untwist this?

I’m working on adapting dripps GH file involute_spiral for 3D printing. So far I’ve stretched the spiral vertically and set up polygonal cross sections for lofting. But the polygons end up twisting the loft in a nasty way.

Is there a way to detect the orientation of the polygons so they can all be aligned the same way? Or should I be generating them differently?

Here is the modified GH file I’ve got so far:

involute spiral 7.31.18 (19.6 KB)

use the PerpFrames component to make the planes on curve.

Most excellent - thanks.