Bore a variety of hole sizes with one bit—just slide the blade to the desired diameter and then tighten the screw. These have two sharp edges for faster cuts than fluted bits and won't cause the surface of the material to splinter. A centering point keeps them stable while drilling soft and hard woods such as pine, plywood, and oak. Like standard flat-blade bits, these drill rough holes but should be used in a drill press rather than a hand-held tool. Also known as spade bits.