I can't find my bean cooler pics?!?!?!
I used a squirrel cage fan out of a car... mounted it in a 5 gal bucket, second bucket on top, kitchen strainer in that and it pulls lots of air...
pete from I have a Bean has a nice cooler that blows air in from the bottom and blows chaff out the top... (using a leaf blower, but he has bigger batches)