When I started turning I bought a cheap HF tool set. They served me well and I actually still have and use a couple of them. Ive been slowly replacing them over the years with Thompson tools. Over the weekend, I took a turning class and the instructor briefly touched on sharpening and since I had brought some Thompson tools to class, he wanted to talk specifically about sharpening "high end exotic" steel. Ive been using the original white wheels that came on my slow speed grinder. He told me those wheels don't actually cut the Thompson steel but rather break it off and that I should be using the blue Norton wheels. A little research on Doug Thompsons website and he says the same and specifically recommends the Norton 3X K Grade wheels. My issue with those wheels are that the finest grit they come in is 80. That seems pretty course to me especially when trying to clean up an edge for shear scraping, etc. Further research, I find people who say that Thompson steel shouldn't be sharpened with anything less than CBN wheels.
I guess I said all that to say, I need an education on grinding wheels. Specifically, grinding Thompson steel. I'm having a fairly difficult time thinking of having to spend upwards of $300 on a grinding wheel but if its what I need, Ill bite the bullet. Talk to me.