Finish quality was determined by our testers by feel and – with the help of a bank of halogen lights raking low across the work surface – by eye. To show the scratch pattern created by each sander, we made a single pass over clear acrylic with 100 grit. These sheets tell an interesting story about the random-orbit action of each sander. The result from the winning Porter-Cable (left) really illustrates the evenness and completeness of this tool's sanding coverage. You can see how a few more successive passes would blend the scratch pattern fully on the work surface. Other tools' scratch patterns were more erratic and require more passes to ensure uniform sanding coverage.
Vibration exposure in the workplace is regulated and monitored in England and some European countries to prevent hand-arm vibration syndrome injuries. Wearing vibration-reducing gloves may reduce harmful exposure. We tried VibraGuard gloves (800-800-0444, www.ansellpro.com) and found that while the full-finger version provides more overall hand protection, the fingerless gloves make it easier to handle the sanders and operate their controls. The gloves made a noticeable difference in the amount of vibration fatigue we felt during protracted sanding sessions, so we've made them a permanent addition to our shop safety gear.
Other Random-Orbit Sanders
Five-inch electrics aren't the right random-orbit sanders for all uses. Our testers also use 6- and 8-inch electrics (top right) with powerful grinder motors for smoothing large areas, and low-profile pneumatic sanders (lower left) for lightweight mobility on some projects. The right-angle tools take two hands to operate and more concentration to keep flat on the work. Pneumatic sanders typically use adhesive PSA disks with no dust-collection holes, and their appetite for air often keeps them in the shop – most job-site compressors can't keep up.
To explore the test category a little deeper, we also tried out two unique 5-inch random-orbit sanders. The Festool Rotex sander (top left) works in random-orbit or geared-down grinder/polisher mode (a rotary mode that has a slight eccentric motion) for a wider finishing range. In grinder mode, the sander removes stock faster than random-orbit sanders, but its relatively low OPM range (3,000 to 6,000) doesn't provide as fine a finish as its tested brandmate in random-orbit mode. The tool has a long handle to combat the twisting forces caused by the grinder action, so it's more difficult to use one-handed when finish sanding. (Festool RO125FEQ, $395)
The Rockwell RK4245K Vibrafree sander (lower right) has a split-pad design that consists of a center circle and outer ring-shaped sanding pads that orbit opposite each other to reduce vibration. In use, the inner pad has a lot of torque and acts like a grinder, while the outer pad moves much less aggressively. The tool is a decent performer, but its undeniable drawback is the need for nonstandard two-piece sanding disks from the manufacturer. (Rockwell RK4245K, $100; 866-514-7625, www.rockwelltools.com)
On/Off switches at the front of the sanders should be easy for one finger on the hand holding the sander to operate for maximum control. Clearly labeled switches like that on the Milwaukee help keep the tool from jumping off the workbench when plugged in. Most of the tools have simple rocker switches that are easy to use, and some are covered with a rubber dust boot. The stiff boot on the Milwaukee makes the switch hard to use, and the slider switch on the Hitachi and the push-through switch on the Ridgid make them both difficult to operate one-handed, especially with gloves on.
Speed-control dials are side- or rear-mounted, and all are well-protected against accidental adjustment in use. The smooth recessed dial of the Hitachi proved especially hard to turn.
The Ridgid has a soft-start feature with an extra-long delay that is hard to get used to.
All of the sanders have eight holes toward the periphery of their pads for collecting sanding dust. Active suction provided by a motor-driven fan draws the dust through the pad and out the rear duct of the tool into a dust container or vac hose. The Festool sander (pictured) has a different hole spacing than the rest and a unique center hole, so it requires its own brand of sanding disks to allow through-the-pad dust collection. To use the same Norton 3X disks as the rest of the sanders, we had to custom punch the nine required holes for all of the Festool test disks. It's easier to find disks from a variety of manufacturers for sanders with the industry-standard eight-hole pattern.