Extended vacuum cyclon
http://www.instructables.com/id/Cyclonic-Dirt-Separator-Using-Off-the-Shelf-Parts/
V1
Mine will be a thein baffle with helix. Built out of a bucket to sit on top of a trash can. There will be a small opening from the baffle to the trash can (1/4 turn, 1" wide), the bucket will be off center so that the dust drops to the center, that should keep the air in the can from spinning. The helix will also be 1" wide and make one full rotation.
V2
I'm going to reuse the thein baffle I've built, it works pretty well. But the bottom is getting clogged, so I'm going to cut a larger opening and make it easier to get into. It also tips pretty easy, so I'd like to give it a wheeled base to make it easier to move and more stable.
V4
https://www.youtube.com/watch?v=QdyVT8WXLxM&index=10&list=WL