I need help with options for connecting a random orbit sander to a shop vac,does anyone make fittings for this ? I currently have a Porter cable model 390 sander. It was one of the first brushless units (I think). Basically i need a 11/2" o.d. to 2 1/2" o.d. adapter. this will help for now. I am considering longer term solutions for the sanding dust issue as well. Has anyone built a down draft table ? What cfm would be required for this ? Also other vac/sander combo options. My current shop vac is a craftsman with a cleanstream filter. The filter is great,I run two of them and clean one and let dry while other is in vac.