Well, I don't have any plans and if I tried to explain how I built it you wouldn't hardly believe me but I do have a pic to show you. You can get some ideas how a hammerhead like me does it. And believe it or not, my belt grinder tracks straight and true and runs at 1750 RPM. Total outlay of cash was under $10 for the whole thing. Sometimes we get lucky and have all the right stuff on hand. That's how this one worked out. I'll be glad to try and answer any questions you may have.
You can see from the pic that the upper roller is a conveyor type roller ($5) and the contact wheel is an 8" square wheel (free). The drive pulley is solid nylon ($1) and all I had to do is drill it out and mount it on the motor. The belt size for it is 2" X 60" and I use it for all of my hogging, what little hollow grinding I do and for profiling blades. It would be great for flat grinding if I'd ever get off my butt and build a platten for it.