In 2007 I started to become concerned with dust in the shop. Since I enjoy designing and building shop stuff, I started searching for parts for a overhead, hanging dust filter. I found a 220V 650 CFM blower that was perfect. ( www.suppluscetner.com ) I also found a filter that was rated a .05 mircrons. So I designed around these two pieces. I decided I wanted to use 12″ x 24″ standard furnace filters as the “pre” filters. The final design was 2, 12×24 filters and the “bag” filter as the last element. This design allows me to use the cheapest 12×24 filter as the 1st stage. Then a second 12×24 filter rated as high as possible. ( These are 3x more expensive ).
The result is a not so quiet overhead filter, that works excellent. Any time I start to cough while working with power tools in the shop, I just turnon the the big filter and the problem goes away.
PS… DO NOT use this while applying finishes. Lots of particles are moving around and end up on the tacky finish. NOT GOOD!!