Find a local HVAC contractor and ask them for a squirrel cage fan, they haul them to the dump by the trailerload so they should give you one for free or its worth a few dollars if they ask. Build a plywood box for the fan that will hold your furnace filters. Woodworkers construct these and often mount them on the ceiling or build them inside a rolling cabinet to remove fine dust from the air in their shop.
Workshop Dust Collection Accessories Free Woodworking Plans and Projects
You can also vent these outside like a dryer vent and skip the filter. If you run it without a filter you need to slow down the motor or you'll burn it up.
You can also buy the same thing if you don't want to build one.
lint in the shop 
