I'm not sure what you mean by a "sawdust fan", but I am thinking to remove sawdust particles from the air in your shop.
I use a window fan, and place a 20x20 furnace filter on the intake side, and that does a great job pulling the fine dust out of the air, wile recirculating it back around the shop.
Now, sorry for the misinterp if you want something to 'fan' sawdust.
