I cut a wooden washer out of a piece of 3/4 ply to fit in the 4" duct. The hole in the ply is cut on the bettom, and a 1 foot piece of vacum hose is glued into that. The whole assmbly is then wedged into the 4" duct of the jointer. Now just hook a shop vac to the hose sticking out of the washer and cut away. Never had a mess since.