I know this is an old thread, but it seemed like the best place for this. I have about 10 hours on a wheeling machine and want to pick up skill as fast as I can. Lots of thinking about what is going on at the molecular level. So, I did some Finite element work to look at stress. The graphic was an insight to me about the difference between true radius and Contact flat anvils. The peak stress is much higher, in the center, on the true radius (elliptical depression.) I can see now how the blending is tougher with full radius.
ewheel.JPG