If you’ve got a decent-sized compressor in your shop, why are you only using it to spray finishes, blow dust off benchtops, and shoot fasteners from a nail or staple gun? When you think of air tools, the impact wrenches and body grinders used in automotive and metal shops may first come to mind. But there are lots of sanders, saws, drills, routers and more that run on compressed air and are perfect for everyday tasks in the woodshop. Many of these tools are pneumatic versions of electric portable power tools. Yet air tools are more compact, simpler and easier to maintain, safer to operate (no chance of electric shock) and — best of all — are often more affordable than their electric counterparts. For example, a 1/4" electric die grinder will set you back $100 - $150 or more, but you can buy a pneumatic die grinder for as little as $10 - $20. Production quality air tools made by companies specializing in pneumatics such as Sioux and Dynabrade cost more, but are built tough enough to handle the heaviest use and still last for decades.
If there’s a downside to using air tools, it’s that most have a powerful hunger for air, meaning you need a fairly large compressor to run them at full capacity. There are a couple of other issues to consider with air tools, although I don’t think either is a deal breaker. Although air tools are not significantly noisier than electric tools, the added clatter of a running compressor can create quite a din in a small shop. Also, the tools’ air exhaust tends to blow sawdust around, and if you work in a cold climate, this cool air blast can feel unpleasant.
Air Tool Operation
Regardless of the size and type of compressor you have, the setup for running air tools is basically the same. You’ll want an air filter/moisture trap and a regulator connected to the outlet of the compressor’s storage tank to clean and dry the air and adjust the pressure to match the tool’s recommended PSI. A flexible hose connects the compressor to the tool. When running air tools with higher standard cubic feet per minute (SCFM) demands, it’s best to use a 3/8" I.D. air hose that’s 25 to 50 feet long. You can get by using 1/4" I.D. air lines with tools that have lower SCFM requirements. If an air tool doesn’t come up to speed quickly or lacks power, switch to a larger diameter and/or a shorter hose.
Most air tools have lever-like paddles that control the airflow and switch the tool on and off. You can reduce the speed/power of the tool by putting less pressure on the paddle. Many tools also feature an air regulation knob, which lets you set the maximum amount of airflow (and thus the speed/power) with the tool’s paddle wide open.
Air tools need to be lubricated regularly to keep them operating smoothly: Simply apply a few drops of air tool oil (in a pinch, you can use 10-weight SAE motor oil) to the tool’s air inlet every day before use. For heavily used tools (or if you’re prone to forget oiling), fit an automatic oiler on the tool’s air inlet. When starting up a freshly-oiled tool, cover the air exhaust with a rag, as oil is apt to be sprayed everywhere. Because lubricating oil can contaminate air hoses and, subsequently, raw wood surfaces and spray-gun-applied finishes, it’s a good idea to designate one hose just for air tools.
Air Tools for Woodworking
Orbital and In-line Sanders
The original air-powered sander, orbital “jitterbug” sanders have been around for decades, used in auto body shops for fine sanding body filler, primer and painted finishes. Their rectangular rubber pads take a standard 1/3-sheet of sandpaper, and their low profile lets them get into tighter areas than most electric orbitals can reach.
Also born in auto body shops, in-line (a.k.a. “long board”) sanders use long strips of sandpaper and work with a back-and-forth sanding action. In-lines are great to use with fine-grit papers for final smoothing of large, flat cabinet sides, panels and tabletops, as well as for fine sanding between finish coats.
Random-orbit and Dual-action Sanders
Compact and powerful, pneumatic random-orbit (RO) sanders come with either 5"- or 6"-diameter pads that take PSA (pressure-sensitive adhesive) sandpaper discs. You can also fit them with a conversion pad that accepts hook-and-loop discs. An RO’s orbit diameter determines sanding aggressiveness: large-orbit models sand more aggressively — best for rougher sanding jobs — while small-orbit models are better for finer finish sanding. Some pneumatic ROs have built-in dust extraction, and they connect to either a vacuum hose or a passive-collection dust bag.
Dual-action or “DA” sanders, long the kings of cabinet shops, employ the same sanding action as ROs, but they have a handle configuration that makes them a better choice for sanding edges, corners and curved surfaces.
Disc and Narrow-belt sanders
Fitted with coarse-grit discs, pneumatic disc sanders are really handy for quickly shaping large surfaces, say to refine a coopered panel into a smoothly curved cabinet door.
Narrow belt sanders run skinny (1/2") belts on a long wand that can get into areas where even a detail sander won’t work. They’re indispensable for smoothing the hard-to-reach nooks and crannies on a project.
Jigsaws and Routers
A pneumatic jigsaw may seem like an odd tool, but its smaller size makes it a good choice for curved cutting jobs in cramped areas, like doing plumbing cutouts on the insides of kitchen cabinets. Air jigsaws are also a terrific choice if you need to do repairs while lying on damp ground under a house or work on a boat that’s still in the water — there’s no hazard of electric shock.
One company, Beaver Tools, makes a line of pneumatic routers and laminate trimmers which are very compact, yet powerful. Accepting only 1/4"-shank bits, these routers are nimble to use for inlay and detail work, as well as for trimming veneers, plastic laminates and solid-surface materials.
Reversible and Right-angle Drills
Sporting keyless chucks and rotation-reversing levers, air drills are just like electric drills, only smaller. Just like a clutch on a cordless drill, you can change air pressure on an air drill to control the amount of torque. Lacking the bulk of an electric motor, right-angle air drills are small enough to get into the narrowest compartments, making them great for drilling holes for furniture and cabinet hardware.
Right-angle and Die Grinders
If you build curvaceous furniture or sculpt or carve wood, you’ll find air-powered grinders extremely useful. Fitted with a carbide-burr wheel, flap-sanding disc (available at welding supply stores) or a carving disc such as the Arbotech Woodcarver, a pneumatic right angle grinder is a wicked wood-eating tool. But using a standard grinding wheel, the tool comes in mighty handy for occasional metal work as well — say, reshaping part of a door hinge.
Air die grinders pack a lot of power into a small package. Their 1/4" collets will accept a wide range of wood burrs, cutters and sanding wheels/discs, making them great tools for carving and refining details — wooden handles, escutcheons, furniture feet, and so forth.