Installing a dust collection system
Here are some pointers for constructing your system:
Use PVC sewer and drain pipe instead of the heavier, more expensive schedule 40 PVC.
Fasten joints with screws rather than glue so you can open the system easily to dislodge jams.
Run a 5″-6″-diameter line to your heaviest chip-producers — planer, jointer, etc. — and locate the collector as close to them as possible. A 4″ line will adequately serve saws, sanders, and the like.
For more on central dust collection, see WOOD magazine, Issue 43, June 1991, ppg. 40-45.
Air and wood particles moving through the dust collection system quickly build up static electricity charges in any nonconductive hose or piping (hose or piping not made of metal). When this static buildup discharges, it could lightly shock the operator or even ignite the flammable wood dust particles inside the piping. If the sawdust burns fast enough, you have an explosion.
A static ground for nonconductive ductwork can prevent static-charge buildup and potential disaster. To install one, simply run a wire along or around the pipe, as shown in the illustrations. Insulated or uninsulated 18- or 20-gauge copper wire, either solid or stranded, works fine.
At pipe joints, leave slack in the wire or install bayonet connectors (Radio Shack has them) to facilitate opening the system in case of a clog. Run a ground wire along each branch, and splice each into the main wire.
Connect the ground wire’s conductor to the dust collector’s metal frame or housing. The other end should extend to the outlet port on the tool, but it doesn’t need to connect to anything, except to keep it in place. (Think of the wire as an antenna rather than as a conductor in a circuit.)
The coiled wire core in some flexible plastic tubing allows easy grounding. Simply strip the plastic away from a few inches of the wire core, then connect the wire to your system ground, as shown in the illustration.
Control the flow
For maximum efficiency in a branched system, shut off the flow from all ports except the one in use. To do that, install blast gates.
You can buy metal or plastic blast gages for various pipe sizes from a number of woodworking-equipment dealers. Or, refer to the drawing below to build a wooden blast gate.
The connectors shown are made from a PVC pipe coupling cut in half and epoxy-glued into place. You can alter the dimensions and couplings shown to fit different sizes or types of pipe.
To mate the 3″ or 4″ system to most of your tools, you’ll need hoses and adapters. The best way to do this is with tapered (not stepped) transitions.