Cyclone units for woodworkers separate out a lot of the woodchips and dust so you don’t have to empty your dust collector or clean its filter as often. Most people gravitate to the smaller trash-can lid models or the clear plastic ones, but the smaller units don’t give the dust much time to settle into the can, and with the plastic units static electricity can build up and start a fire*. If you’re looking for something better, Gary MacIntyre Associates offers a big cyclone unit made of galvanized metal.
This cyclone unit will work well with your standard metal trash can. It’ll catch particles larger than or 200 to 300 microns (.008”-.012”) and will get over half of the particles down to 20 to 50 microns (.0008” to .002”) — the rest will go on to your shop vac or dust-collection system.
You can get the unit with a standard 4″ duct or a 6″ duct — the 4″ version sells for about $200.
* I’ve never seen a cyclone unit start a fire, but there’s enough worry about it that they’ve started putting grounding wires on the plastic models.