Hi , Been having troubles modeling a Can scroll (worm ) to feed tin cans into a machine

my issue is for the first part of the scroll it needs 4 revs at 200mm pitch then at say 4.25 turns start to tighten up fairly quickly , as this happens the pitch becomes smaller than the diameter i am trying sweep and it will fault .

With a fixed pitch helix i can use a pitch smaller than the sweep profile diameter and it will not fault and produce an appearance close to what the original looks like .

any help would be appreciated