Mark - you'll need to do one of two things to make a tapered rope spiral with Aspire. Aspire will not control your B axis - it doesn't have the ability to generate code for it. So, your choices are:
1. (Takes the most time) Generate the vectors for a rope toolpath with the Spiral Layout gadget, then the toolpaths using a rope cutter cutting a profile on the vectors. Preview this toolpath, and save the preview image as a component. Then, create a smooth tapered component using a 2-rail sweep, as Michael suggested above. Add the rope toolpath component to the tapered component, adjusting height of the tapered component as necessary to get it to the right radius. Toolpath again with a ballnose cutter and use this toolpath to actually cut it (this approach will work for machines that do not have a tilting table). Unfortunately, you can't just use a rope cutter to do the actual cutting in this option because the trailing edge of the cutter will dig into the work as it goes down the taper.
2. (Takes least time, but requires you to write a tiny amount of G-code). Generate the vectors for a rope toolpath with the Spiral Layout gadget, then the toolpaths using a rope cutter cutting a profile on the vectors. Save this toolpath as a g-code file for cutting. In a text editor, open the g-code file and insert one line of code after the header block to move the B axis to the appropriate height. You will need to calculate this yourself - will take a little trigonometry. In Mach3, the code would look something like "G90 G0 B0.5" where the number following B is the number of inches (or millimeters if you're in metric) you want to move the B axis. You should probably put another line of code toward the end of the program to move the B axis back to 0, i.e., "G90 G0 B0"
The difference in cutting time is hours for option 1 and a few minutes for option 2.
D&S Artistic Woodworking http://www.dsartisticwood.com