I have built two down draft style benches for collecting metal particles and dust from porting cylinder heads. I am using a Harbor Freight 2hp dust collector to pull air thru the cabinet work area. The work surface is perforated metal on one bench and fiberglass deck grating on the other bench. I have a V-shaped trough below the work surface which is opened in the center of the trough. I have a piece of 4" PVC attached to the trough and connected to the dust collector.
The two grinding cabinets work good. I would like to increase air flow thru the bench to collect dust and particles more efficiently.
My idea is to build a plenum below the work surface and install a squirrel cage blower from an a/c system air handler. I've given this idea to a friend that has some HVAC experience plus works with a ventilation/mechanical engineer.
I'd like to gather some thoughts and ideas on a this project.
Ray
Pictures of my first DIY downdraft cabinet/bench