Yep, making worm wheels is fun!
I turn a groove around the circumference of the wheel with a tool radiused to the root diameter of the screw. Here is a link to some photos...
http://users.tpg.com.au/users/daveg/drives.html
This allows for deeper meshing of the worm/wormwheel. it also allows a straight cut cutter to keep meshed during the cutting.
The first set of drives I made used stainless worms and aluminium Wwheels. I had the Wwheels hard-anodised by Hawker deHaviland at Bankstown. After 3 years of use there was no sign of wear. although the mount wasn't goto.
The second set were made from stainless worms again and naval brass (almost as hard as steel!) Wwheels they are still in use today. It's goto.
The latest set are using naval brass worms and Delrin Wwheels. Here is a video of them being cut...
http://www.youtube.com/watch?v=mWVqs...eature=channel
I've yet to finish the mount. Maybe this Easter!
I hope this helps Steve etal