The tapping apparatus disclosed has a feed screw for moving a boring bar axially upon rotation of the boring bar relative to the feed screw. A drive sleeve rotates the boring bar to provide such relative rotation and to rotate a cutter attached to the boring bar to cause the cutter to cut a hole in a pressure vessel. Both the feed screw and the drive sleeve are rotated independently by fluid motors. The pressure of the fluid to each motor is maintained constant, after the initial relative rotation between the boring bar and the feed screw is established, to permit the feed rate of the cutter, i.e., the speed at which the boring bar is moved axially by the feed screw, to adjust itself automatically to decrease as the cutting load increases and increase as the cutting load decreases thereby automatically adjusting the feed rate to the cutting load on the cutter.