A board fastening tool has a tool body and a driver having contiguous drive elements mounted in the body. A top element is mounted to slide in vertical track when hit from above. A bottom element is mounted to drive a fastener diagonally out of the body and into a board to fix the board to the floor. The top and bottom elements are connected by a spring steel ribbon device sliding in a curved track so that vertical movement of the top element is converted to diagonal movement of the bottom element. The spring steel ribbon device has a pair of spring steel ribbons joined to each other at respective ends thereof and separate from each other over an intermediate region.