On my '48 Unisaw I cut a rectangular hole for the 4" port at the back. I fit the plastic adapter available from Rockler, etc to that. The motor cover was missing so I made a rectangular plywood cover and cut slots in it for ventilation of the motor. Brackets off the side handled the fence, etc when off the table. I built a ramp inside the unit out of 1/4 tempered hardboard. It went from the bottom of the front cover to the base of the DC inlet at the back of the cabinet. I also make 1/4" side ramps to feed onto that base. It helped the movement of dust by feeding to the bottom ramp. I blocked the air between the table and the cabinet. That gave me air through the lower front cover and the motor side slots. Having the air enter the front and go right down the ramp gave me very good flow of the saw dust. Oh, I taped the side ramps to the base with foil tape and also used the foil tape on the side ramps up top. Every once in a blue moon I'd remove the lower door to see how the cabinet looked. The bottom ramp would be clean except for some caked dust at the joints L & R. I left it as it created the easiest air flow out of the cabinet. You will always have eddies in air flow so why fight it. Yes, the table was off the saw to enable installation of the ramps. This worked really well.