Distinguishing Designs

Testing compressors may not be as exciting as testing sliding compound miter saws or circular saws; after all, a compressor pretty much just sits there. Still, that didn't keep the creative engineers from incorporating user?friendly features that my crew and I really liked.

The DeWalt is the most feature?packed. First, I love the ball?valve drain lever. It's in a good location and, thankfully, there's no chance someone can strip it with pliers, which happens all the time to the leaky screw valves on my compressors. No debris will fill the threads, either, which also causes screw valves to leak. (I liked this feature so much, I retrofitted my old compressors with ball valves.)

Second, I'm impressed with the compressor's adjustable pilot valve, which controls the motor's start/stop function. You can set the pilot valve to run in a start/stop fashion (the typical way) or you can bypass it for constant run. Constant run is desirable for heavy usage, according to DeWalt, and saves wear on the motor by avoiding constant on?off cycling. The toggle switch is pre?wired for operation at 120 or 240 volts?you only need an adapter. Running at 240 volts requires a lower current draw and produces less motor wear. Wiring at 240 volts also discourages a carpenter from running the compressor from a 100?foot 14/3 power cord and tripping every breaker within a mile of the job.

The no frills/all function Rol?Air has a real standout feature: a glass bubble for inspecting the oil. It's right on the pump and allows you to check both oil level and cleanliness easily. I didn't worry about breaking it, either.

The fold?away handle on the Porter?Cable is handy and makes transport and storage easier, but taking the cake for special features is the unit's unique four?port manifold. You can attach four separate hoses to it and regulate the pressure from it. Not only does this neaten up a tangle of hissing fittings and hoses that are hard to plug in and reach, but the manifold also detaches. This allows you to run a lead hose from the main unit and bring the manifold to a central location inside the building?leaving the machine and noise outside and closer to the power source.

One note of caution, especially for crews using 3/8?inch fittings: The air runs from the Porter?Cable's tank?unregulated?to the manifold. The manifold, where the regulator is, has a 3/8?inch fitting to tap into the air source, and more typical 1/4?inch fittings for hoses. The compressor runs at 165 psi and if someone unknowingly bypassed the manifold and plugged directly into a hose, 165 psi air would go directly to your nailer. Not only would this be bad news for your O?rings, but also your nailer may shoot through 1/2?inch sheathing or, worse, fail in some other way. I'm surprised there's no permanent warning sticker or proprietary fitting.

Tank Size

I replaced my dependable 8?gallon twin tank compressors with these bigger, taller, and fatter units during the test period. As I wheeled one into my trailer, I wondered what I was really getting out of it; after all, my 8?gallon compressors work fine. The answer has two parts: First, these bigger units get more air to the crew's nailers because the tanks are twice the size of what I normally use. Second, according to manufacturers, the larger units last longer, because their larger reserves require them to cycle on and off less. Also, they refill more quickly. This results in moving parts doing less moving than in a smaller compressor run under similar conditions, resulting in a more durable compressor.

Oil Change. The Craftsman has the most sensible oil?change feature; it's easy to fill and drain, and the drain plug is well placed to accept a shallow pan or funnel. The next best is Rol?Air's, which is easy to fill and drain, though I'd replace its drainpipe with a 2? to 3?inch extension of threaded pipe for easier access.

The Campbell Hausfeld and DeWalt oil changes are more challenging. Campbell Hausfeld's has clear access to the fill port if you pour from the bottle; if you use a funnel, the air filter obstructs it somewhat. Draining it is a problem. There's no drain pipe, just a drain plug, which causes oil to drain on the mounting bracket and tank. Filling the DeWalt is easy, but draining it is problematic because the drain pipe is too short. There's enough room to wiggle a funnel in there and drain the oil but not enough room to conveniently use a pan. It's not that you couldn't rig something up to catch the oil, but if the drainpipe was 3 to 4 inches longer it would prevent the issue.

The Porter?Cable is the only oil?free/maintenance?free compressor in the group.