One- and two-stage units. A single-stage dust collector pulls all the debris through a spinning impeller (suction fan) and deposits it in a collection bag or drum. Modern designs can handle dust, chips, and shavings without appreciable equipment wear. However, try to avoid sucking up screws and nails as they can impact the impeller and possibly create a spark.
A two-stage system deposits heavier chips and shavings in a drum before they reach the impeller. Only the fine dust touches the impeller on its way to the second storage container. This design prohibits heavier objects like screws and nails from hitting the impeller.
A two-stage collector has more room for storage, but it takes up more floor space. If you're doing a ton of planing and jointing, a two-stage collector is the way to go. Single-stage collectors contain dust just as well and take up less space, but you have to empty them more often.
Grounding. Collecting dust creates a static electrical charge. Dust moving through plastic pipes can create static sparks. If you duct your whole system with plastic, the entire thing must be grounded with copper wire to prevent a dust fire or explosion in the worst-case scenario. On my own systems, I run 5-inch metal flex-tube from my tools into a single 5-inch metal heating and cooling duct, which runs to the dust collector. The metal tube eliminates the need for ground wires because the metal pipe dissipates the static charge. It's also grounded by virtue of its mechanical connection to the grounded dust-collection unit.
Fine dust collection. Most standard dust collectors come with utility bags that trap 5-micron-and-larger dust particles, but it's that super-fine, powdery dust (from 1 to 4 microns) that's the real hazard. Upgrade to a 1-micron filter bag to eliminate the fine dust.
Accessories. You can save time on connections by using quick-connect fittings that connect to the hose and easily switch from tool to tool. Tool-activation switches are great add-ons that make your system easy to turn on and off. Safety shroud-equipped foot switches that regulate air pressure work well. Another great control device is a remote switch that works like a garage door opener. My favorite is the Long Ranger 2 made by Penn State Industries (See "Sources of Supply," on the next page). It controls 110- or 220-volt motors and works from anywhere in a shop.
Purchasing. If budget or space is an issue, start small and buy an affordable, portable dust collector. It will be a valuable tool in your shop or on site, if you upgrade to larger collectors. Having several dust collectors increases chip and dust storage capacity. If you've got one collector, you have to clean it more frequently and it'll wear out faster.
Expect to pay about $350 for a good 1,200-cfm, single-stage dust collector, about $475 for a double-stage unit, $40 for a 1-micron upgrade bag, and another $40 for connectors and hoses for each tool.
If you go with the workstation concept, you can set up a dust-collection system for three woodworking machines for about $500. If you're planning a large, central dust-collection system, check out Delta Machinery's booklet to help design a custom installation. You may need to have a system like this professionally installed.