I ran a 4" PVC pipe from my collector along the wall behind my lathe and mounted it on the wall. It is about mid point along the length of the rails and ends a bit below spindle height. Then I used a reducer and continued with 3" lok Tite hose (or tube or whatever it is called. It is a ball and socket type product. Stiff enough to stay in position when you let go of it, but easy to bend around) with enough length to reach any point along the working length of the rails. I put a small funnel on the end of it. It has worked great for dust, getting almost all of it, mostly because the ball and socket design of the lok tite lets me quickly position the hose right where I want it. It is nearly worthless for chips, but that is fine for me. I wanted the dust dealt with.
Dave