Creating an helicoidal swept around a container...

Hello all,

New challenge.... Please I would like you to analize the 3D model....  

To take into account:  Distance of 20 mm in the initial sketch must be respected.

What I need:  The swept to go around the container in a smooth way, sliding homogeneously.

If you see the 3D model attached from the FRONT view, and later on from the RIGHT view, I feel not seeing the same thing !!!!  

I don't know whether or not there is an alternative solution, instead of cutting the 3D model with a Surface (Which comes from the defining dimension initial sketch), and using later an Intersection curve in order to obtain the 3Dsketch which will be later the path of the sweep.

I'm becoming crazy, because it might be a matter of visual perception, but by this method, I feel I don't get what I'm looking for, an homogeneous sweep down all around the ed model.

Thank you very much in advance !!!

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