Chamfer wheels on the same tool you sand them round
Cut a length of 3⁄4 ×4" scrap with one end angled 45°. Mount the dowel pin in the angled end (its exact location depends on the diameter of your wheel). Place the wheel on the pin, slide the jig forward in the slot until the corner of the wheel contacts the spinning disc, and rotate the wheel to make a chamfer.
—John Carter, Jenks, Okla.