8 inch duct for downdraft table/lathe downdrop

[Fred Thompson]

I have a 2005 Oneida Super Dust Gorilla (appx 1700 cfm) with 8 inch intake hooked up to an all 6 inch PVC duct system. I have a newly made large downdraft sanding table right next to my medium sized lathe and thought "more is better" when controlling dust/chips. These tools all sit within 10 lineal feet from the 8 inch cyclone intake. I was thinking about adding an 8 in drop for these 2 tools, add some type of 8 in lathe hood, add 8 inch takeoff to the back of the downdraft and I am off to the races. I feel as a very generalized statement that chips depend on FPM and dust depends on cfm. Increasing the duct size to 8 inch surely could not hurt and since the tools are next to the cyclone and the cost is less than $35, why not. My main question to the forum is will this 8 inch duct help with the lathe chips and dust from the sanding area? I do not do a lot of lathe work, but when I do the chips fly everywhere.

[Clay Crocker]

One thing I would caution you about would be the possibility of overheating the motor if you don't have enough air resistance in the duct between the tool and the cyclone. It may not be a problem, but I would check the amp draw of the motor while running on the 8 inch drop just to be sure.

[Brian Kincaid]

Just a few things to check:
The 8" ducting might not maintain enough air velocity to keep the lathe shavings moving (downdraft table is probably ok). The Bill Pentz spreadsheet (google) is what I used to calculate my plan.
I echo Clay's comment about overheating the motor. Cyclones must be loaded or the motor will overheat.

-Brian