The easiest way to create something like that IMO is to draw the helix first, then a straigth line in the center that is your axis and then simply do a loft between them:


For a bit of thickness you can use the Shell command afterwards and then boole your central axis cylinder with the result...

Did something similar a while ago with a smaller helix in the center... (couldn't make the second attachement viewable inline with the message edit function...???)

Cheers,

Tom