ROUTER BITThe basic edge-forming bit, the corner-rounding bit rounds an edge to a given radius. The tool is shouldered to cut a fillet. The cut can be used to ease edges, as a simple profile, or as a part of a complex one. Also known as roundover, rounding over and quarter-round. If a smaller pilot bearing is used, a second shoulder can be produced, in effect making the bit a beading bit.