Ask the average homeowner what their favorite DIY activity is, and chances are slim they will mention sanding wood. No surprise there. Sanding is no more popular than scraping paint or doing your own dental work. But if you’re an active do-it-yourselfer, sanding wood is unavoidable. Electric power sanders are the best, quickest, and easiest way to sand wood smooth. In short, they’re the best way to make an excuriating task a little more pleasant. There are several different sizes and types of sanders available, but below are detailed descriptions of the three most versatile types: belt sanders, orbital finishing sanders, and random-orbit sanders. With these three portable power tools—and the correct abrasive—you can sand virtually any surface or edge you’re likely to encounter. (Word of caution: Most electric sanders have a dust-collection bag or dust port for attaching a wet/dry vacuum. However, it’s still advisable to wear a dust mask—or better yet, a dual-cartridge respirator—when sanding wood, especially if the surface is painted or varnished.) Belt Sander When smoothing large, flat surfaces, especially really rough ones, nothing beats the high speed and brute strength of a belt sander. This heavy tool accepts sanding belts, which are continuous loops of reinforced abrasive cloth that fit over two cylindrical drums. The tool’s motor drives the rear drum while the front drum spins freely. A tension-release lever allows you to easily slip the belt onto the drums. To keep the belt running true, most sanders have a tracking adjustment knob that you can turn to center the belt. When smoothing flat boards, always sand parallel with the wood grain to avoid scratches, and keep the sander moving at all times so you don’t sand a depression. Belt sanders are also ideal for smoothing the narrow edges of boards. However, it’s best to clamp several boards together and sand all the edges at the same time. This technique, known as gang sanding, not only saves time but also produces better results because you’re not trying to balance the wide sanding belt on the narrow edge of a single board. A belt sander is also great for removing an old finish, such as paint, varnish, or stain. Always start with a coarse 60-grit belt and work your way progressively through finer and finer grits until you reach the desired level of smoothness. (The larger the number, the finer the grit. So use progressively higher numbers.) Again, sand parallel with the wood grain and don’t press down too hard or you’ll clog up the abrasive belt. Let the weight of the tool provide the right amount of pressure. Belt sanders come in four standard sizes, which refer to the size belt they accept: 3x18 inch, 3x21 inch, 3x24 inch, and 4x24 inch. The 3x21-inch model is the most popular size; it provides the best combination of speed, power, and balance. The 3x18-inch size is compact and easier to control, so it might be better for novices and users with smaller hands. A 3x24-inch model provides a bit more sanding surface than a 3x21-inch sander, but it’s also less stable and a bit harder to control. A 4x24-inch sander is designed for heavy-duty sanding of large, flat surfaces. Unfortunately this behemoth is hard to control and can cause more damage than good in the hands of an inexperienced DIYer. Orbital Finishing Sander An orbital finishing sander is lightweight, easy to control with one hand, and relatively quiet. It’s also virtually impossible to damage the workpiece with this type of sander. On the other hand, because it’s relatively docile, an orbital sander isn’t particularly useful for heavy stock removal. It’s intended for ultra-smooth wood sanding, rounding over sharp edges, sanding off hardened wood putty, and knocking down dried coats of paint or varnish. Orbital sanders are often called quarter-sheet sanders because they accept one-quarter of a sheet of standard 9x11-inch sandpaper. Two spring-loaded clamps hold the sandpaper against the sander’s flat, square pad. The pad vibrates in tiny circles, or orbits, allowing you to sand in any direction. Random-Orbit Sander Falling somewhere in between a belt sander and orbital finishing sander is the random-orbit sander. It’s easy to confuse a random-orbit sander with an orbital sander: The two names sound alike, and the tools share a common design, compact housings with rounded palm-grip tops. However, there’s one small but very important distinction between the two tools: An orbital sander has a square sanding pad, and a random-orbit sander has a round pad. That one variation makes all the difference. The round pad on a random-orbit sander moves in “random orbits,” meaning it vibrates in tiny circles, like an orbital finishing sander, but it also spins in circles. As a result, this single compact tool can be used for both stock removal and ultra-smooth sanding. And because the pad vibrates and spins simultaneously, it all but eliminates swirl that ordinary orbital sanders sometimes leave behind. A random-orbit sander won’t remove wood as quickly as a belt sander, and it’s slightly more difficult to control than an orbital finishing sander, but the random-orbit sander is arguably the most versatile portable electric sander you can own. If you were interested in buying only one sander, I’d recommend this one. Most random-orbit sanders have a one-handed, palm-grip shape, which most DIYers prefer, butD-handle and barrel-grip (similar to a right-angle grinder) models are also available. Models come with either a 5- or 6-inch-diameter pad; the 5-inch size is more than sufficient for DIY projects. Finally, some random-orbit sanders accept peel-and-stick PSA (pressure sensitive adhesive) abrasive discs, while others use hook-and-loop (a.k.a.: Velcro) discs. PSA discs are less expensive, but hook-and-loop discs are much faster and easier to change and reuse. Source: Popular Mechanics
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http://www.popularmechanics.com/home/reviews/power-tools/know-your-power-sanders-and-how-to-use-them-13314160?click=pm_latest