TIMBERLINE by Amana 320-54 TIMBERLINE CORNER ROUND 5/8 Radius 2 Flute with Ball Bearing Guide 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.