Area-Crosscut between track & belt-7 main line belt. 2 men were going to build cribs on belt side of stopping. 1 was throwing crib blocks thru open mandoor. The other man was picking these up & putting them against rib where cribs were to be built. As he bent down to pick up a crib, the other man threw a crib hitting the end of victim's left ring finger. (Had prot. gloves on.)