Poor air flow at SawStop dust collection port? Solution?

[Steve Mathews]

My SawStop ICS has two 2.25" branches that come off of the 4" main dust port. One is for the overarm setup on the saw and the other is for the fence on a SawStop inline router table dust collection box. The branch at the router has a lot more air flow than at the overarm port even though it comes off the 4" at the same 90 degrees. The only difference is the router port protrudes into the 4" main whereas the overarm port is flush with the main. I'm wondering if this is the reason for the poor reviews of the overarm setup and that the overarm tee that SawStop provides should be more like what they provide for their router.

Edit: While the port at the router table dust collection box is 2.25" the port for the saw overarm is actually 1.5".

[Steve Eure]

Steve, you didn't say if you have any blast gates on the hoses. I do not have this type of setup, but if you are not using the router and/or table saw, I would suggest closing off the one that you are not using and see if that helps. Keep us posted on your results.

[Steve Mathews]

Steve, you didn't say if you have any blast gates on the hoses. I do not have this type of setup, but if you are not using the router and/or table saw, I would suggest closing off the one that you are not using and see if that helps. Keep us posted on your results.

There are 4" blastgates serving the saw and router table. I isolated each system to compare the airflow from each of the ports described.

I put together something out of sheet metal for the saw overarm port to approximate the setup on the router table. See pic below. It improved the airflow considerably. The obstruction that it created in the 4" is probably not large enough to cause a problem.
SawStop Dust Port 001.jpg

[Dave Mills]

If I'm seeing this right, you have a 4" line coming toward your saw, which then is split to a 4" and a 1-1/2" line. I haven't done the math, but for me that's just something I don't do. I imagine the static pressure dropping though the floor, though I'm happy to be corrected. For my router (I don't have an overarm solution for my TS), I blocked off SawStop's attempt to do the same, and I run one 2-1/2" hose to the top of the table at the fence, and a 4" hose underneath. They enter my metal ducts into a 6", not into a 4".

[Jim Dwight]

I run a 5 inch metal pipe to my PCS but I branch off a 3 inch line by a wye, not a 90 degree fitting, right after the blast gate and later neck the 5 inch to 4 inch for connection to the PCS. Airflow seems OK, dust does not build up in the saw compartment and the overarm gets the dust if the blade is buried in the wood. If the blade is on the edge, it probably gets some of it but there is a lot on the table. I need to try a drop down of plexi for these cuts.