Thought I'd post a vid of my completed grinder.
>click here<
To speak to the contact wheel/bearing issue, I had the following experience.
When I first mounted the wheels (8" & 3" poly contact wheels, "economy" versions from USAKnifemaker), I used a 1/2"-13 bolt and washers/bushings to space the desired amount. I tightened the bolt until the wheels had no play, but during operation the bearings would heat up. Not just a little, but a LOT! Obviously, this is not right. I took the wheels off and looked them over and it made sense. Not sure why I didn't get it before, but there you go!
The wheels have bearings pressed into each side, but there is no through bushing. The wheels that Rob sells at Beaumont Metalworks do have internal bushings, and over tightening is a non-issue. But I didn't have another $170 to spend, so I fixed the problem much like Jamie did with his build: I mounted each contact wheel to the platen with 1/2"-13 bolts, using a jam nut to secure the bolt to the platen and to eliminate play or it being rattled out of place. I used machine bushings (1/2"x5/8") to take up slack where necessary. There is no side pressure on the bearing races because I used 3-1/2" bolts, which have a roughly 2-1/16" unthreaded shoulder--perfect for the contact wheel to ride on. This solves the problem for the cheaper wheels, and eliminates side pressure on the bearings, which will ruin them pretty quick.
By the way, I talked to Tracey at USAKnifemaker.com the other day and he told me that his contact wheels (the polys) are different from Sunray in that his have a tolerance of 3-4 thousandths-of-an-inch in side-to-side play; whereas, those from Sunray supposedly have more. It came up because I measured the total variance in side-to-side motion on my 8" wheel to be ~12 thou.
Hope this helps.
JJ