Dust filter
Doug,
I built mine with a squirrel blower unit ( can't recall the cfm rating ) and have 2 filters in each side. It is 12"x24" and it takes 2, one inch filters on each side. You have to use the good air filters, or it defeats the purpose. I take the filters down every couple of weeks to clean ( vacum ) them and then replace the outer one when it gets bad, and I put the new one on the inside, if this makes any sense. I would not be without one, as mentioned earlier it is best to catch it at the source, and this is my secondary filter. My shop is 16x24 and this filter does a good job. I put a louvered grill on the front so in the winter it blows the warm air downward to help circulate the heat in the shop as well. Total investment was approx. $70.00 and that was buying the blower new.
Here is a picture of mine.
Doug