The goal of dust collection isn't complicated. Robert Witter, founder and president of Oneida Air, puts it quite simply: "You collect as much dust as you can at the source and then stop it with a rated fine-micron filter." It really is that simple.
So if it's such a no-brainer, why do woodworkers tolerate inadequate dust collection? It's not that they aren't trying to collect the dust they create. But unfortunately, many are only cleaning up the mess they can see — and missing the fine particles that are most harmful to their health. Even with the best intentions, their efforts and resources are often wasted because of manufacturers' overstated claims. They end up with systems that aren't capable of collecting most of the dust created by woodworking tools.
Cost and the perception that a new dust collector won't be as much fun to bring home as a new table saw are also factors. It's true that a large system can be relatively expensive, but most home shops don't require a lot of equipment, and there are many incremental improvements you can make that are not expensive. It's also true that a dust collector won't make the same kind of visible contributions to the quality of your projects as other tools, but it will make your work more enjoyable and your shop a healthier place to spend time.
Design and installation
The frequency that you use your shop shouldn't affect the type of system you install. The type of tools you use and the number of tools being used simultaneously (how much dust is produced at one time) are what counts.
A small shop system is not difficult to design. Draw your shop layout on paper or on a computer to determine all the duct lengths and components that you will need. Place the tools that produce the most dust closest to the collector. If you have a large space with several tool areas or you run multiple machines at the same time, consider using a dust-collection manufacturer's professional design services. We worked with Oneida Air to design the layout for the HANDY workshop. These services provide a rough design and materials quote for free after you submit a questionnaire and basic shop layout. For a fee or with a minimum purchase they will provide detailed drawings of the plan and a complete shopping list.
Installation is not difficult. A small shop system can usually be installed in a day or less and requires only a few tools, including a tape measure, a wrench set, a drill/driver and a saw capable of cutting sheet metal.
Ductwork, fan and filter
A dust-collection system is made up of three primary components: the ductwork, fan and filter (see "Anatomy of a Dust-Collection System," below).
The ductwork provides the path for the airflow from the dust source to the dust collector. The goal is to minimize restrictions that reduce airflow: Use adequate-size, smooth-wall pipe and make the runs as direct and straight as possible, with gradual turns.
The most commonly available duct pipe is flexible 4-in.-dia. hose. Unfortunately, it isn't large enough to allow the necessary airflow for tools such as a table saw or portable planer, which create large amounts of dust. For these tools you'll need to use a minimum 5-in.-dia. smooth-wall pipe.
Steel ductwork is a better option than plastic pipe, such as PVC. Unless it's properly grounded (which can be difficult), PVC builds up a static charge that will result in annoying shocks and can spark and ignite wood dust.
The fan directs air through the ductwork. Fans are rated by the volume of air they can move, measured in cubic feet per minute (cfm). Be careful when comparing the fan ratings of different dust collectors: Manufacturers can exaggerate or misrepresent fan ratings because they are not regulated. Reputable manufacturers present fan ratings in relation to static pressure (SP) and provide a chart called a fan curve (which displays pressure vs. volume). It's not critical that you understand how to read this curve; the fact that it is made available is a good indicator that you can trust the ratings.
The filter is the final stop in the system. It puts the "collection" in dust collection. Without an adequate filter, a dust collector is nothing more than a dust recirculator — and this is where many dust-collection systems fall short.
Filters are rated by the smallest dust particle (measured in microns) that the filter media will capture. Filter for a manufacturer to misrepresent. A reputable manufacturer will use thirdparty testing and specifically state the percentage of particles captured at a specific micron level. For example, a filter description might state that it captures 99.9 percent of test material from 0.2 to 2 microns at 11 fpm.
Installing your system
Follow the manufacturer's instructions to assemble the collector. Align the inlet port in the direction of your duct lines.
It's ideal (although not always feasible) to clear space on the floor to lay out and assemble each drop. Lift the assembled drops into position, connect them with horizontal runs and attach them to the walls with straps or shelf supports.
Fasten the duct components with sheetmetal screws. Tip: magnetic screw bit holders are the perfect size for driving No. 8 sheet-metal screws (inset).
Seal duct connections with silicone or foil duct tape. Do not use silicone on joints that you may need to disconnect frequently in the future.
Sometimes the only option is to improvise your connections. Flexible silicone tape works well to seal connector seams.
If your shop is built over a framed wood floor or you have the luxury of a high ceiling, consider framing an elevated floor and installing the ductwork below the subfloor. The ports and outlets can be located near the base of stationary tools.
Types of collectors
Two types of collectors are commonly used in small shops. Bag-style collectors feature a top-mounted fabric filter bag and a plastic collection bag below the top filter. Fine particles are captured in the filter bag, and larger particles fall into the bottom collector bag.
The problem with most bag collectors is that the standard filter bags are often small, they don't capture particles smaller than 1 micron, and they must be cleaned frequently to maintain performance. You can upgrade the performance of most bag-style filters by replacing the stock woven filter bag with a cartridge-style filter or a larger filter bag made from felted media. A larger bag or cartridge provides greater surface area and slows the air speed through the filter for better particle retention, allowing more particles to fall into the bottom collection bag.
Cyclone separators are more effective. They feature a cone-shape tube that swirls dust, separating out larger particles, which fall into a canister below the cyclone, and sending smaller particles to a cartridge filter.
Another option to consider, if it's permissible where you live, is to skip the filter and canister and simply blow the dust outside. If the pile outside grows too large, you can spread it out or shovel it to another location to decompose. A dust collector that is located outside the shop or that vents ratings, similar to fan ratings, are easy the air outdoors will create negative pressure inside the shop. In these cases you must provide a source of makeup air. Opening a window works well. We installed a 20 x 20-in. HVAC grate. In these cases, be especially cautious to avoid back-venting any shop heat source that uses a vent pipe, such as a wood stove or gas heater.
The design of the tool port contributes to the effectiveness of dust collection. For many power-tool manufacturers, dust collection is still little more than an afterthought. Most tool ports are too small, and many are not located in the optimal location to direct the dust.
Tool ports vary in size, so finding the right connector or combination of connectors to fit both the tool port and the collector hose can be a challenge. Attach reducer fittings as close to the tool as possible, keeping the hose or duct diameters as large as possible leading up to the tool.
Dust collection is gaining attention as we learn more about the hazards of wood dust. Consider your dust-collection strategy, and look for ways to improve it. An effective system makes spending time in your shop more enjoyable, and a clean shop gets noticed — you might even find your dust-collection system getting more attention than any tool in your shop.
6 Keys to success
Whether you're installing a new system or you're hoping to improve your existing setup, these strategies will help you optimize dust collection.
- Capture fine dust at the source. Purchase tools that feature well-designed dust-collection ports, or modify the ports on your tools to collect more dust at the source.
- Use large duct pipe. Increasing the duct size from 4 in. dia. to 5 in. dia. will double the airflow. Make reductions near the end of the drop or at the tool port, not on the main line.
- Keep it smooth. Run smooth-wall pipe as far as you can, and save the flexible hose for the last couple of feet at the tool connection.
- Replace sharp turns with gradual sweeps and angles.
- Seal seams with silicone caulk, foil tape, flexible silicone tape or a combination.
- Use a good-quality filter that will capture fine particles (0.3 to 1 micron). Upgrade your old woven filter bag with a larger felt bag or canister filter (see photo above). For best results select a filter that features 1 sq. ft. of filter media per 10 cfm of air moved.
Don't overfill your barrel
Emptying an overfilled collector barrel is a dusty disaster. Most woodworkers avoid this mess by frequently opening the barrel lid and checking the depth of the dust. This manual check system works, but is easy to accidentally forget. An easier method (that won't be overlooked) is to install a depth indicator, such as the new infrared indicator (see photo) from Oneida. It senses when the dust level reaches a designated distance from the lid and then turns on a bright red flashing light that is impossible to ignore.