2 OTHER EE'S ALONG WITH INJURED WERE INSTALLING AN IMPACT BED FRAME AT BELT. 2 EE'S WERE ON OFF-SIDE OF BELT, & INJURED WAS ON WALKWAY SIDE PUSHING IMPACT BED FRAME IN. WHEN THE FRAME FELL INT O PLACE, IT PINCHED HIS THUMB BETWEEN THE FRAME & THE RAIL CAUSING A LACERATION TO RT. THUMB.