Wood dust is one of the most overlooked safety hazards in any woodshop. It can be a long-term health hazard as well as a short-term irritant to your sinuses, lungs, and skin. That's why every shop owner should take dust collection seriously.
From a lifetime spent in woodshops, I've developed efficient dust-collection methods that effectively suck the finest dust particles (down to 1 micron) out of the air. If you're operating a busy, high-volume shop, you'll need a central dust-collection system that may require some engineering to get the best results. But, if you have a small shop, you can use a much simpler layout with less complex components that will make your shop, work, and lungs cleaner. The basic components of a small shop dust-collection system include a dust-collection unit with enough power and storage capacity to handle what your tools throw at it; some 4 or 5-inch pipe/duct materials; and the right accessories to activate your system. Think about where you're going to place your dust collector so it'll do what it needs to do without taking up space.
The first rule in designing a dust-collection system is getting a collection unit with enough cubic feet per minute (cfm) of air movement to handle your shop tools' dust and chip output. The second is laying out your tools, collector, and ductwork efficiently. And third is deciding whether to go with a single- or double-stage collection system.
Rules at Work
Cfm. Proper airflow is everything with dust-collection systems. I recommend using a collector that moves a minimum of 650 and maximum of 1,800 cfm. For my money, though, 1,200-cfm systems provide the best balance of price and power.
I recommend using 4- and 5-inch pipe as much as possible because air and dust move more freely through these larger pipes. And the fewer bends in the line, the easier it is for dust and chips to pass. If you need to turn a corner, make it up with a series of shallow-bend fittings rather than one sharp 90-degree turn.
Layout. Some woodworkers swear by a centrally located, single dust-collection unit linked to all their tools by a series of pipes. Instead, I prefer a workstation layout for a small shop. It puts the most dust-collecting power within easy reach of your tools and eliminates having to buy the most powerful systems. And it reduces the amount of pipe you need for your system.
A central unit requires long runs of pipe with various bends to channel debris from the dust maker to the dust taker. This lowers the system's static pressure and reduces dust collection efficiency.
Although larger central systems use collectors that move 1,200 to 1,800 cfm, you still shouldn't exceed pipe runs of 40 feet. Keep in mind every 90-degree bend equals 10 feet of straight pipe. For very small shops with limited tools, a central collector may be the only way to go. But if you have the room, group tools in threes to create smaller, freestanding dust-collection systems. For example a table saw, planer, and jointer work well together.
Put the collector against a wall and cluster the tools around it (table saw, center; jointer, left; planer, right) so you have plenty of infeed and outfeed room. If you have more dust-generating equipment like a stationary sander and shaper, create another stand-alone group. This layout provides the easiest dust-collection set-up, use, and maintenance. Every six months or so, beat the bags clean outdoors; this reopens their porosity. I have three 1,200-cfm, single-stage, workstation-format dust collectors in my 3,000-square-foot shop and they work great.