Screw threads in rhino for Mac

I want to make screw threads using rhino for Mac. If I start with a helix how should I access the roadlike option in Sweep 1 Rail to run a cross-section curve along it that stays properly orientated and gives a smooth parallel result?

Hello - if the thread is oriented vertically, use the ‘RoadlikeTop’ setting. i.e. make your thread axis parallel to World Z. Does that make sense?
Thread.3dm (1.3 MB)