Bemfarmer,

I would look at the "ScriptArray" script Michael made.

http://moi3d.com/forum/index.php?webtag=MOI&msg=5595.18

If you remove the scaling part and then look at adding vertical steps (Like the circle array command), possibly incorporating the "VariablePitchHelix" stuff, it would make a loftable, single smooth surface to subtract, for the screw.

Not that that's "Easy" or something. If anybody can do it, you can!