Been doing a lot of digging on the forum about the dust collection systems everyone has been building and I have been wondering about how the size of the inlet opening effects the FPM required to pick up find dust.

According to what I have been reading you need lots of FPM and CFM to pick up the dust. Optimum hose size has to be around 6" to get the FPM needed to pick up the dust.

Here is an excel spreadsheet I found that has some good information and has a built in calculator for hobby and commercial dust collection systems.

http://billpentz.com/woodworking/cyclone/StaticCalc.xls

Thanks

Joe