Remember the short-grain inlay I made? Those are inlay for the arcs at the ends of the table. These are similar to the sides, just much wider; so, I made new templates. These templates are simply clamped to the table and the router run along.
I adjusted the templates one each side so that the end groove hit the side groove at a 45 degree measured from the corner of the table. In other words, I didn"t worry about the template being parallel to the end of the table (though it should be!) It was more important for the grooves to perfectly line up.
I stopped the router just short of where the grooves meet. I finished squaring that with my very small chisel.