[MrForbes]

You need to guard the area where the chain meets the sprocket. The chain itself isn't very dangerous, but if a finger gets near where the chain goes onto the sprocket, bad things can happen. A flat plate of polycarbonate (ie. Lexan) over the side of the sprocket, extending about an inch past the edge of the sprocket, and mounted as close to the chain as you can get it, should suffice.