Grinding wheels

With all the differnt sharpening jigs, majority make referecne to an 8" wheel to get the 7"from face and 4" down from center( Ellsworth theory). What about having only 6" wheels, would the infor for setting up hold true also? Can your opinions be defined?

You can set up with about any size wheels,I have the 8" slow speed and 6" high speed and both work fine for me.You take what ever sharpining jig you have and just then line up your tool to the center of the wheel for whatever angle your after and sharpen,just use a light touch on your wheel,so as not to over heat the tool.

Ken pretty much nailed it. Although a smaller diameter wheel will produce a slightly deeper hollow in the profile, they should still work fine.

The 6" wheel has far less useful life than a 8" wheel.
The wheel is round. You are always grinding at the tangent point. The reason why the old style Ellsworth jig is so fussy about the height and distance is the jig is squarish block. The pivoting leg is at the back of the jig; the front of the jig would interfere or can't clear the grinder guard.