Portable Compressor - Canadian Woodworking Magazine

Tool Review


Portable Compressor

Lead photo: front view

The air compressor is a valuable addition to any woodworking shop. Air tools are generally less expensive than their electric or battery counterparts, and they're more economical to repair, as well as being more compact and lightweight. If you locate the compressor outside your work area, in an enclosed space, you'll hear nary a toot from the unit or your tool. And you don't need a large industrial compressor for shop work; a small portable compressor will run all but the most demanding tools.

Over the past eight months I've been using the Ridgid OF45150 Portable Air Compressor in my shop and on various job sites. I'm very pleased with this unit; it has proven to be easy to use and highly dependable. Although I normally use it on an intermittent basis with a headless brad nailer or a spray gun, it's also proven an excellent choice for installing hardwood flooring and framing. And, at $398.00 it's easy on the pocket book.
Different Choices
Compressors come in a variety of configurations. They can be single or two stage (that is, having one or two cylinders that produce the compressed air). Two cylinders produce higher pressure, more than what is needed in the typical workshop. They come as air or water cooled, oil-lubricated or non-lubricated, and single or double air tanks. The Ridgid has a single cylinder, air cooled, non-lubricated compressor with twin stacked tanks.

Back View

A Motor and Compressor
Like most compressors, the Ridgid consists of an electric motor that powers a piston within a cylinder to produce compressed air, which is stored in its two tanks. The compressed air drives the air tools, while the motor automatically cycles on and off to maintain the correct air pressure in the tanks. The Ridgid compressor has an induction motor rated at 1.8 running HP (3.25 peak HP), among the highest for comparable models.
Air Power Over Horse Power
While you need a motor to run the compressor, the critical factor in determining the power of a compressor is the volume of air it delivers at a specific pressure, and not its horsepower rating. Air volume is measured in cubic feet per minute (CFM). Because CFM varies with atmospheric pressure, temperature and humidity, a better measure of volume is the standard cubic feet per minute (SCFM), which takes these variables into account. You'll usually see the SCFM given at 90 PSI, as most shop tools require this pressure to operate properly. A higher SCFM at any given PSI level is preferred, as air volume is what runs your tools. Obviously, the quality of the compressor pump will have an impact on the SCFM level. The Ridgid provides up to 6.2 SCFM at 90 PSI, a level that is comparable to or exceeds the rating of other models on the market.
Regulated Air
When the air in the tank reaches a pre-set limit (generally 125 PSI), a pressure switch stops the motor. The tank pressure gauge tells you how much pressure is in the tank. While some tools may require a lot of air pressure to operate, most of the air tools in my shop operate at the 70 to 90 PSI level. A regulator on the compressor enables you to match the air that comes out of the compressor (referred to as the hose pressure or the air line pressure) to the air pressure requirement of the tool you're using. Turn the regulator in one direction and it increases the outlet air pressure, turn it the other way and it decreases the outlet pressure. A regulated outlet gauge lets you monitor the outlet air pressure. Just in case something goes wrong, there is a safety valve near the regulator that automatically opens if the pressure switch malfunctions. On the Ridgid all the gauges and valves are easily accessible and large dials are easy to read. The ratcheting regulator allows for precise pressure selection.
Oil or None
While oil lubricated units may offer somewhat more efficiency and run quieter, oil-free compressors, like the Ridgid, make better sense for the small shop, particularly for spraying finishes. They also require minimal maintenance. I use the Ridgid to clean dust off my furniture before finishing and for spraying shellac or water based finishes, so I certainly don't want oil droplets contaminating the wood or the finish.
All Tanked Up
While you do need a tank to store the compressed air before it's used, you don't need a large one, especially if you're using the compressor intermittently. What you do need is the ability to produce a constant supply of air, so having an efficient compressor and motor is more important than a large tank. The 4.5 gallon tanks on the Ridgid hold enough air to set a lot of brad nails before the compressor kicks in. Of course, for more aggressive nailing, such as when installing hardwood flooring, the compressor runs more frequently. You won't see the duty cycle posted on these smaller compressors, but expect about a 50% cycle, which means that the motor should be running no more than half the time that the compressor is being used. I have never found this to be a problem as most of the drilling, nailing, and spraying that I use my compressor for is intermittent.


Taking Care of Business
To get compressed air to your tool you connect an air hose to a outlet coupler. There are two outlet couplers on the Ridgid, which is a great feature. This enables me to attach both a ⅜" quick connect coupler with a ⅜" 50 foot hose, and a ¼" coupler to a ¼" 50 foot hose, to handle the different air tools I use. When purchasing air tools remember that the SCFM requirement for the tool shouldn't exceed the maximum SCFM your compressor can deliver. For the Ridgid this is a healthy 6.2 SCFM at 90 PSI.

Although my compressor spends most of the time in the shop, it moves easily to a job site. The heavy-duty 1" tubing on the Ridgid protects the critical components of the compressor on the job site and in the truck.

If you store your compressor inside, moisture shouldn't be a problem. If it is, then you can get an in-line air filter that installs between the air hose and your tool.

At the end of your work day turn your compressor off, then manually pull the safety valve to empty the tank of any remaining pressurized air. Also, open the drain valve so any water inside the tank can drain out. Every few months clean the intake filter.

For increased work productivity and efficiency in your shop, consider the benefits of a portable air compressor.

For more information on the Ridgid OF45150 compressor go to www.ridgid.com or visit your local Home Depot.