EE WAS USING UTILITY KNIFE TO CUT SMALL OPENING IN RUBBER CONVEYOR BELTING MATERIAL BEING INSTALLED AS AN END SKIRT BOARD ON A TYROCK WET SHAKER SCREEN. THE EE WAS IN THE PROCESS OF CUTTING A SMALL HOLE WHEN THE KNIFE SLIPPED OFF THE WORK AND STRUCK HIS LEFT INDEX FINGER, CUTTING A PORTION OF THE FINGERNAIL AND FINGERTIP.