Am I missing something (well, I already knew that [big grin]), but isn't this kind of switch - I plucked this off of Lee Valley's website, but it's pretty standard - what is requested here? It keeps the ancillary item, presumably a vacuum, on for six seconds after the primary item - saw, etc., - is off.
http://www.leevalley.com/US/wood/page.aspx?p=63013&cat=1,42401&ap=1