Bending Copper Tubing

I am starting to loose patience with this one. I need to bend 1/2" soft annealed copper tubing into a spiral cone. each coil is 2" less in diameter than the last and each coil is 1" higher(from the horizontal) than the last. This is a continuous coil in the shape of a cone. The diameter of the coil is from 4 feet to 6 inches. I have tried so many jigs that my head is spinning. I understand there is a copper pancake coiler that will do the trick but I cannot find it on the web.

Each time I try to turn the coils, I either get kinking or flattening of the tubing. I am trying teflon and a specially manufactured spring as an internal support. The copper tubing is somewhat deformed even in in the coil that I receive and the internal support has to be 3/8 Inch in diameter to even fit. That is another issue: Pushing 65 feet of internal support into tubing that is in a coil to begin with. I have been told that HDPE is the best internal support for this type of process. Some one is Australia uses this successfully. Sure, just try to buy HDPE is a rod of 3/8 diameter in 65 or 140 lineal foot lengths without ordering 5000 pounds of the stuff. So far no luck. Oh, the 140 lineal feet is for the production model of my project. The 65 feet is only for the prototype.

What am I building? A solar thermal collector

Picture below:

Any help at this point would be appreciated.

A word to the wise: In my research I used PatentStorm in searching for conflicting patents and found none. A lot of work later and after a lot of $ with a patent attorney, he found several conflicting patents. Problem: I used a recommendation from a CR4'er. Patent Storm does not have patents that go way back and that is where my attorney found the conflicts. Use something else, Google patent is a good start. I did eventually file for a patent and that is pending. But it has cost me considerable time and money that I might not have spent. Many patents for solar energy were filed in the 30's and 40's.