EE WAS HELPING A MAINT MAN CHANGE A SCRAPER CUTTING EDGE. THE JACK USED TO LIFT THE EDGE DID NOT RAISE HIGH ENOUGH TO LINE UP BOLT HOLES. EE USED 4 BY 4 PIECE OF WOOD AND PLACED IT ON HE JACK STAND, THAN PLACED THE CUTTING EDGE ON TOP OF IT. BECAUSE THE EDGE/ WOOD WAS NOT SECURED OR CONTROLLED, IT SLIPPED AND SHIFTED CATCHING THE EE'SFOREARM BETWEEN CUTTING EDGE AND PADDLE.