J. Phil Thien's Projects

I have a Harbor Freight dust collection system that I wish to modify with a Thien baffle.  I plan on using a 31 gallon galvanized garbage can for the dust collection system using the lid with holes cut into it to fit the inlet and outlet.  My question is should there be a distance between the bottom of the inlet elbow to the baffle or should it be resting on the baffle.  It would seem there should be separation from the bottom of the elbow inlet to the baffle to allow air to circulate around/below it.  Thanks.