Originally Posted by
Dan Cameron
Not so, Roger
If the center to center distance of the two runners is greater than the center to center distance of the miter slots, even by a tiny amount, the outside edges of the runners do the guiding and the inside edges don't even touch the slots. Else if the center to center distance of the two runners is less than the center to center distance of the miter slots, even by a tiny amount, the inside edges of the runners do the guiding and the outside edges don't even touch the slots. Just two edges do the guiding like a single runner configuration.