Mine has about 1 mm clearance so there is not any contact with the router so no grease,I also removed the small metal pin (it fell out making my router holder rings). Using the vacuum creates an inward suction of air so very little dust escapes. The port is for setting the but height and also clear so I can see the router bit and be sure everything is OK when cutting. The bent plastic is very easy to make. My z-axis allow the router to lift beyond the base to change the bit without a problem. I put the vacuum exhaust on the right due to the spin of the bit and have not had any problems with buildup. Here is a video I made of the Z-axis and older (looser) dust collection. Hope this helps, Jon