Reply by jmos

The 2.5” hose really chokes down the flow. DC’s move a lot of air but don’t have tremendous suction. An easy answer would be to use your shop vac for DC with the sander. Shop vacs move less air but have greater suction. In addition, if you have a HEPA filter in your shop vac it will trap more of the really fine dust that sander like to create. It would also help to minimize the length of the 2.5” hose, the longer it is the more resistance.

You could try an experiment, I don’t think it will help, but it might, and it’s easy to try; open up more ‘area’ to the DC and see if that helps (second 2.5” hose, second 4” hose). It should lower the suction, but if you’re really choking off the impeller it might help.

-- John