6" ducts OK with 4" DC port?

[Roger Bean]

Many thanks to Joe and others for answering questions I've had for a while. I'm running 2HP old Grizzly DC (6" outlet with factory dual 4" Y) with about 25 ft of 4" rigid pipe. Then flex to machines. Worked, sort of, kinda, pretty much, but not spectacular. Recently upgraded to a huge filter bag from American Fabric Filter. My flow and performance improved substantially. I'm now no longer planning on upgrading the main line to 6". Actually best thing I did for dust collection was installing a remote so I actually turn it on whenever I use a machine! Comments?

[Nicholas Lingg]

Air flow will not be the major problem, clogging at the 4" reduction will be. I had to do what Alan did and open every thing up to allow the large clumps of chips from the planer and jointer to pass throught.