When I go back to the grinder after heat treat the wheel doesn't contact the whole hollow, like it needs a slightly larger diameter contact wheel to clean it up. Has anyone else noticed this, and is there a slightly larger than 8" contact wheel for this?

Bill, you can change the effective radius of your contact wheel by rotating (slightly dropping) the butt of the knife handle as you draw it across the contact wheel. Here's a sketch to illustrate what I'm talking about.

http://www.cowlesknives.com/forumpix/contact.jpg

Bill there is actually a radius difference as the coarse grinding belts are thicker resulting in a wheel/belt radius that is slightly larger than the wheel with a thinner fine belt on it.

It is not much but you will notice it more with the heat treat discolouration present. Don's suggestion of dropping the handle end slightly will work very well. I guess we all have done it at one time or another and not even realized that we were doing it.

So you are compensating for the larger diameter created by a course grit belt by tilting the blade. I'll try that, I was rocking it.
I've also talked to Contact Rubber Corp. and found they can make me a 8.1" contact wheel. I may try that soon.