Abstract: A workpiece fastening device usable on a machine tool fixture, comprising an elongated tubular body having knurling along the outside of the top end of the body, a taper on the inside thereof, and a plurality of slots extending longitudinally about half the length of the body. A lock washer with a yieldable portion is welded to the bottom end of the body to allow a workpiece to be pulled flush against a fixture. The tubular body is slip-fitted into a through-bore in the workpiece until the lock washer rests upon the fixture, and a bolt having a head taper matching the taper in the tubular body is then inserted through the body and is threadably received in the fixture. Upon tightening of the bolt, the top of the body expands causing the knurling to grippingly engage the bore in the workpiece. After the body is completely wedged in the bore, further tightening of the bolt causes the lock washer to be distorted slightly thereby allowing the workpiece to be pulled flush against the fixture.