In the shop, we make chips, shavings, and dust. We don't want them in the air or on the surfaces.
Hoods and Valves
A central vacuum system in a woodshop is only as good as the design of the hoods at each machine or station. Most machine manufacturers do a lousy job of designing for dust collection--it's an afterthought rather than an integral one. We have put a lot of time in designing and building hoods to direct the air over the process. To concentrate the air flow where we are working, we have built valves at every station.
Conveying the Dust
Once picked up by the air flowing into a hood, the particles have traveling to do. We want them to get to a bin at the back of the shop. The volume of air moving (cubic feet per minute) and the speed of that movement (linear feet per minute) are critical to capture of the particles and to keeping them moving. As we move from station to station, opening and closing (or forgetting to close) valves, the equations for calculating pipe diameter, runs, and intersections are ever changing--leaving many decisions of pipe size and length of run to informed estimation.
The vacuum draws air over the work at sufficient velocity to carry the dust to the bag house where it drops in the bin or is filtered by the bags.
We return the air to the shop through very efficient filters to retain its conditioning and to capture the very fine particles that get through the bags.
Recycling and Disposal
From the bag house collection bin, we convey the dust and chips to another holding container and, in the process, mix it with water. We can then handle it with front loader or shovel without putting the fines in the air. We compost and mulch with some of this material, neighbors come for some, most goes to the dumpster.