I am trying to reverse engineer a feed-screw.  The design has a variable pitch, variable diameter of helix, and variable profile.  The profile is where I am having the trouble.  The profile changes from 15mm to 14mm to 12mm at certain points.   I have looked at multiple ways of doing this and I keep running into hurdles.  What would be the best method ?

In addition, I have another feed screw that the swept profile intersects and I'm trying to do a swept cut which crashes.  What would be the most efficient process? Swept surface profile, then close off and convert to solid and do a subtraction?

Any pointers are greatly appreciated. 

Regards,
Derek