Out with the bad air, in with the good

Many woodworkers hook up a 4" dust-collection hose to a mostly enclosed tool cabinet, such as one below a router table or downdraft table. They figure that by pulling 4" worth of air through a 1" bit opening, the dust and chips ought to go screaming through the box and into that dust hose. But in truth, they're choking off the airflow, killing the dust-collection efficiency.To remedy this problem, simply install a dust-collection blast gate on the cabinet, opposite the hose for outgoing dust, as shown. By opening this blast gate, you create a "river" of air flowing through the cabinet. Debris gets pulled into the river and carried downstream to the collector. If you lose too much suction with the gate wide open, gradually close it until you achieve maximum dust collection.—Jim Kahl, Edgewood, Md.