Tornado Part

Hello,

I am wanting to create a Tornado, that will be 3D printed.  For the example, the base will be 1/2" dia and the top diameter may 3" dia, with 1.5 revolutions and 5" tall.  I thought it should be easy, but can't find the correct combination, I guess.  What I think I need is a lofted boss, based on a helix curve.  The problem that I am having is getting the loft portion to work.  I cant get the top profile to and the helix curve to related, so that it can follow the helix.... Any help would be appreciated

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