I have read many articles about dust collection and the differences between a shop vac and a dust collector. I am still stuck on one major issue for me; how does one connect table saw, mitre saw, router table to a 4" dust collector when all their ports are 2 1/2"? My understanding is that the reductions severely inhibit the dust collectors ability (which was also my experience as I tried it). I switched to my 6.5 hp shop vac but it cannot handle more than one or two at a time at best and when I add a dust deputy into the mix, everything gets worse. Would really appreciate some direction. Thank you

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    usuall a shop Vac is used for only one tool at a time. A dust collection system on the other hand is usually hooked up to a system of pipes, which are in turn attached to machines. I you have ports you can close so only one pipe extracts dust, I do not see a problem with reducing the diameter for the attachment to the tool. I would avoid 90° bends in the pipes though. Commented Jan 28, 2019 at 10:55
  • If your tool has a 2.5" dust port then it has a 2.5" dust port. You use a reducer to go from your 4" main run to the 2.5" port. You're only sucking through a 2.5" pipe for a few inches in the tool and to the port exit, after that, you're into the 4" dust collection piping and all is good.
    – FreeMan
    Commented Jan 29, 2019 at 19:16

1 Answer 1


There are many adapters and reducers available for dust collection hoses and fittings.

Here is a link to one: 4 to 2 1/2 reducer.

Will the reduction reduce the ability of the dust collector? Sure, but it's still doing a better job than the shop vac. And most can handle running multiple tools at the same time.

The advantage of the dust collector vs. a shop vac is in CFM, or how much air it can suck/cycle. If you look at a 2hp dust collector, the CFM will be around 1500cfm vs. a 6hp shop vac around 180cfm. That's moving a lot more air.

With my table saw, I have a dust collector hooked to the back port and an additional over the blade suction. Removes most of the dust.

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