Weldon Holemaking

Counterbores, sometimes called spotfacers, create a flat-bottomed cavity at the top of an existing hole so that a bolt, nut, or other part is hidden beneath or sits flush with the top of the hole when installed into it.

Countersinks expand the top of an existing hole in a workpiece to allow countersinking screws to install flush with the surface of the workpiece. This helps prevent the workpiece material from swelling when a screw is inserted and tightened down.