I have solved the problem. I decided to try one of those step adapters today, and cut it down so it isn't clunky, just so I could go ahead and use my routers with dust collection now, before I order a hose and wait for delivery. Who knows, maybe this was the intended design to start with on this item, to cut it to fit. All I know is it worked, and very well. Details below.
I bought a step adapter from Lowe's today for about $10.98 plus tax. It worked so well that I went back for a second one, and now I am planning to just get a couple more so all my Dewalt routers are outfitted with one of these, plus I will end up with some extra 2 1/4" vac ports for making other dust collection devices, such as an enclosure for my table router, or maybe something for my drill press.
This vac adapter is made of a flexible rubber, and easily trims with a utility knife. I cut the smallest segment off, and then, leaving segments two and three together, I separated them from the remaining larger end. This is all that's needed to adapt my smaller shop vac hose to my routers, and it's a good firm snug fit, but comes apart easily with a little twist when needed. Cutting the smallest segment off still left an opening that was too small in the narrow end of the piece I wanted, so I went up about 1/8" and trimmed away the part where they had overlapped, and that left me with the exact right sized opening to fit the adapter on the router.
This fits all my Dewalt routers, the DW618 plunge base, and the compact DW611 fixed and plunge bases, both. Absolutely perfect. And it did not end up clunky feeling at all as I had feared.
Since I was left with two of the larger ends, I attached them back to back, with four 1/4-20 screws and nuts, 3/4" long, and a thin foam gasket between them that I made using a peel and stick foam pad, available in hobby stores, just to keep any air losses down. I put this on my sliding miter saw, since the plastic vac attachment it came with doesn't stay in place very well. I put a hose clamp on it to hold it on, and the larger shop vac hose I have here fits into this very well, and stays in place snuggly.
I'm stoked. I have $25 in the things I bought today, and ended up with 3 vac adapters (miter saw, and two of my routers). I will get two more to finish off all my router bases so I don't have to pull them off and on as I switch between routers, and I will have enough left to make other things as well, using the larger ends that are left over.
Last edited by Duane Bledsoe; 06-13-2015 at 09:43 PM.