Hi FDP,
I have modified the method to achieve the helix's to loft.
In the youtube video the helix's where created by two radii and distance between them thus creating a conic helix. The method I have used produces a helix on the surface of the hour glass shape as shown in Photo. You will need to produce 2 Outer & 2 Inner hour glass shapes to create the Cam Roller Groove.
Cheers
Barry