CAD for Spiral Cam

[chmorroni]

So one of the parts for our "shooter/launcher/thing" this year is a spiral cam. We have done the calculations as far as what the maximum and minimum radii need to be, but I have no idea how to design or CAD that. I would assume (from a blurb that I saw of a previous thread) that there is some kind of equation to make this. There will be no load on the cam while it is being adjusted, as it is going to be used as a fancy mechanical stop, so I would like the radius to change evenly over the entire circle.

Any tips on designing and CADing this?

EDIT: I (as the only person on our team that knows CAD) just got SolidWorks, but I am still in a transition state between that and Inventor, so either would work. However, I would prefer SolidWorks.