Outfit Your Shop with Air

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This article is from Issue 32 of Woodcraft Magazine.

Bring a whole new level of versatility, speed, and convenience to your woodworking.

By Jim Harrold

Now, more than ever, woodworkers turn to air for a whole assortment of workshop tasks, from driving nails and staples to sanding to applying fast-drying finishes. Depending on what you want to do, the investment can range from $200 (for a portable compressor and nail gun) to well over $1,000 for a whole-shop plumbed system and a 60- to 80-gallon compressor with a full array of tools, hoses, and accessories. To help you bring air into your shop, we’ve fashioned a short course to discuss the advantages, sort out your options, and walk you through an accommodating plumbed system. As you’ll discover, an air-outfitted shop works harder and saves time while adding versatility.

Air’s advantages

Citing specific tasks where air tools have come to the rescue (as well as the Norm Abram’s storied nail-gun episodes) sells the notion of having an air-powered workshop. Such woodworking tasks include assembling a carcase, nailing moldings in place, holding parts in position until the glue sets, jig-building on the fly, finish-sanding, and applying several coats of spray finish in a single day. Indeed, you can drive a half dozen brads into your project by the time it would take you to pick up a hammer with one hand and a nail with the other. You won’t have errant hammer dents or smashed thumbs. The brads are so small that they don’t split the wood when entering, nor do you need a nail set to sink the heads in a separate operation.

Assess your needs

Let’s say that air has blown you over and you now want to explore your options. You first need to ask what tasks you want to perform. For many, power-nailing ranks first. The woodworking tools grouped here include pin nailers (which shoot needle-like 23-gauge 3/8"- to 13/8"-long headless pins) for delicate jobs such as nailing in glass stops or making small mitered frames, and brad nailers (which shoot 16- or 18-gauge 5/8"- to 2"-long brads) for building furniture and jigs, applying molding, and assembly work. Some brad nailers also accept staples for attaching cabinet backs, upholstery, and underlayment in areas that won’t show. Throw in a dedicated air-powered stapler gun, which is a handy relative to the nailers.

For cabinet construction and crown molding installation, as well as light carpentry tasks, you have finish nailers (which shoot thicker 16-gauge nails), and, finally, framing nailers, used to build houses. For all of these needs, you likely can get by with a smaller, less expensive compressor that provides strong spurts of air rather than a strong continuous flow. (See “Tool Air Requirements” and “Understanding Air Pressure and Flow” above to refine your assessment and help you choose the right compressor.)

Requiring a strong, continuous flow are random-orbit sanders, straight-line sanders, and spray guns, which depend on compressors with more volume and storage capacity. Do the tasks associated with these air tools interest you?

Next, decide if you want a portable compressor or one with a fixed location having a rigid pipe and fittings system and enough hose to reach throughout your shop. The latter offers maximum versatility, but requires running lines and spending more money. With these issues decided, you now have a starting place.

Understanding Air Pressure and Flow

Most compressors can supply pressurized air to single-shot tools, but if you want to use sprayers and sanders, you’ll need to think about volume. The rate at which a compressor can deliver a volume of air is noted in cubic feet per minute (cfm). To compare apples with apples, makers calculate standard cubic feet per minute (SCFM) as cfm at sea level with 68° F and at 36% relative humidity. SCFM ratings are listed at a specific pressure, most commonly 90 psi (if you reduce pressure, SCFM goes up, and vice versa). When choosing a compressor you’ll want to be sure that it can supply the quantity of air at the pressure that your tools need. (If you plan on running several air tools simultaneously, add up the combined SCFM needs of those tools.)

This 26-gallon unit meets the air flow needs for spray-finishing.

System components

Whether we’re talking portable or whole shop, an air-powered system consists of three parts: 1) a way to build up air pressure (a compressor); 2) an air-delivery system (a hose or rigid piping and a series of regulators, filters, and connectors); and 3) the tools themselves. Each requires its own discussion.

• Buy The Right Compressor

For home shops a portable compressor with a 1-6-gallon tank serves low-level needs­—blowing off projects and nailing. If you want spray-finishing, step up to a 7- to 30-gallon tank. Sanding requires a constant high SCFM air flow. The solution: a stationary 60- or 80-gallon tank having a 240-volt service.

Compressors come in two types: oil-lubricated and oil-less. Oil-lubricated models have their bearings lubricated inside an oil-filled crankcase. The oil makes for a quieter operation and longer service life, but these units require monitoring the oil level and oil changes. Oilless models do not need lubrication. They require less maintenance, are more portable, eliminate the risk of contaminating finishes with ambient oil, and cost less. The downside: they need new piston rings about every 1,000 working hours. In addition, oil-less compressors are noisier. If your compressor is too noisy, install it outside the shop.

• Air Delivery Options

Hoses: A hose serves as the most common means of delivering compressed air to tools. Small compressors often come with a length of vinyl (PVC) hose. A better choice is a special polyurethane recoil hose (Woodcraft #149029). This spring-like hose coils itself into a smaller space, but stretches out when you need it.

Composite rubber hose works, too. It’s strong and stays flexible even in cold weather, while refusing to coil up. Choose ¼" (I.D.) hose for most woodworking shop needs and make sure you have enough of it to reach the far corners of your shop. A good way to control and store long hoses in your shop and prevent a tripping hazard is with a retractable hose reel, mounted to the wall or ceiling.

Fixed Piping: The ultimate system for an air-powered shop uses fixed, rigid pipe. This eliminates tripping over the tangled mess hoses create. You can run the main trunk line throughout your shop and have “drops” wherever you’re likely to need air supply—at the workbench or spray-finishing area, for instance. Each drop only needs a short hose length that’s long enough to hook up to an air tool.

Piping options include galvanized, black iron, or copper. We recommend copper. It doesn’t rust and installs easily. Note in the system mock-up featured here, we chose ¾" copper pipe for the trunk and branch lines for maximum airflow from the compressor. These become further reduced at tool connector locations as shown. Be sure to use the thicker-walled copper pipe labeled “L” instead of the “M” pipe.


• Other Fittings

To complete your rigid-pipe system, you’ll need an air shut-off ball valve at each drop. While your compressor should come with a regulator to control the pressure sent out to the entire system, add one or more regulators at drop locations (for your finish spray gun, for example) to control pressure locally. With these you can adjust the pressure as needed simply by turning a knob. Also, install a filter in the finishing drop to keep oil and dirt in the line from contaminating the finish material.

Because condensed water in the line can damage tools and the delivery system itself, slope the main pipe run ¼" for every 10' of run. This lets the moisture in the line run downhill to the drops. To remove moisture, simply fit a hose to the system, open the ball valve, and blow it out. Another strategy is to use an in-line desiccant air dryer. As the air flows through the beads in a replaceable cartridge, the beads absorb water vapor and change from blue (dry) to pink (wet).

Lastly, you need a method to attach the hoses to various tools or tool hoses to the system. This is done via “quick disconnects.” These fittings allow pressure to remain in the system when you remove the tool or hose. Quick disconnects may require an additional fitting to connect them to the system.

Set up a mobile system

If you mainly want air to shoot brads and most of your assembly tasks takes place in one area of the shop or around the house, outfit your shop with a smaller (1- to 7-gallon) portable twin side-stack, hot dog, or pancake compressor, 25 feet of hose, a quick disconnect, and a 16-gauge brad nailer. You can always add other nailers later. Today you can find combination kits that include everything you need for about $300, or put together your own system by buying each component separately.

To build a ¾" copper pipe system, use a pipe cutter, flux, a flux brush, solder, a map torch, wire brush, and pipe cleaner. Clean the joining surfaces, apply flux, slip the parts together, and solder the joint.

To connect threaded fittings together, wrap the male fitting threads with Teflon tape for a leak-proof seal and then tighten the parts with opposing wrench action (Inset).

How to install a copper pipe air system

If you opt to build a full-service system, study the Anatomy of a Copper Pipe Air System shown here, which starts at the compressor and continues through the trunk line into three branch lines, terminating with a setup for a finishing room. Note the called-out details for individual connections. Some mix cast-iron fittings with brass or copper, a common approach.

Also, check out Photo A and B to see the tools and techniques used to assemble a copper pipe air system.

Creating a layout plan, locating your stationary compressor so it won’t take up valuable shop space or trouble you with noise. Then attach your trunk line to the ceiling or high on the wall where it won’t get in the way. Standoffs (bell hangers) make it easy to fasten copper pipe to the wall or ceiling while providing fitting clearance. Add drops as needed around your shop. Each drop should terminate with a shut-off valve, a quick disconnect, and a short length of hose. The drop above right simulates a setup for a finishing area and includes a regulator and filter. Once installed and powered up, charge the system with air to check for leaks. 

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