Q never told the Voyager crew how to create the spatial flexure.
In one episode, Janeway asked Q why he doesn't just take Voyager home. Q then hangs a lampshade and basically says 'because then there wouldn't be a series'. If you don't know what lampshade hanging is, it's where you keep the audience's suspension of disbelief by pointing out a plot hole and then moving on. Kitface 11:33, June 14, 2011 (UTC)