While pulling core tubes, the EE was guiding wire line onto spool w/hammer. His gloves were pulled into the wireline drum where his 3 middle finger of (L) hand were caught in the cable wrap. I n a jerking reaction, the EE pulled back to free his hand and subsequently amputated his 3 middle fingers below 1st knuckle. At hospital, required amputation of middle finger to 2nd knuckle.