Source: TOOLS OF THE TRADE Magazine
Publication date: September 21, 2008
By Eric Leoni
Porter-Cable's new 390K 5-inch random orbit sander looks different because it is different. It is built around a new type of DC motor that Porter-Cable calls the EnduraTech. Besides not having brushes to replace, the motor has 71% fewer wear components, which should result in much longer tool life, according to the company. This DC motor also gives the sander more torque and a much shorter profile, much like the look and low-slung balance of pneumatic, random orbit sanders commonly used in manufacturing industries.
Feel is important in a tool that spends a lot of time in your hand. The squat design makes the sander a little harder to hold than taller models because there is no pronounced undercut in the body to wrap your fingers around, and the grip is fatter than most. This mainly affects lifting the tool, though it felt pretty comfortable while sanding. The rubberized surface on the top and sides helps keep a grip, especially for dusty hands.
There is a speed control dial at the rear left of the tool, but as a lefty, I couldn't reach it during use. I had a hard time turning off the center-mounted power switch, too, but at least the location of these controls kept me from accidentally turning off or changing the speed of the sander while working.
The sander has an 8-foot cord, which is nice but, in my opinion, you can never get that extension-cord connection far enough when sanding long boards. The tool also comes with a nice dust collection canister and small case.
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