Power sanders are often categorized by the action by which the motor moves the sanding pad and sandpaper. This action can take one of three forms:
Rotary: On some sanders, the motor simply spins a circular pad to which the sandpaper is affixed. An ordinary power drill can become a rotary sander simply by affixing a sanding disk to the drill’s chuck. There are also rotary sanders that are designed specifically for this purpose, often used for metal work or paint stripping.Random orbit: A random orbit sander moves the sanding pad in small, irregular circles, which prevents the sandpaper from leaving distinguishable patterns in the surface being sanded. Most random-orbit sanders are hand-held tools, but there are also some large upright floor sanders that use this type of action.Rotating belt: Portable belt sanders and upright drum sanders both work by means of wide sanding belts that spin around powered drive wheels or drums. They are good for removing lots of material in a hurry, and for this reason require some skill and practice to use effectively.
An electric power sander is the way to go for many home projects. Every home workshop should include at least one, and more advanced DIYers will probably want more than one. And you can also rent specialty sanders for occasional use. Random-orbit sanders come in several sizes, but the most common sizes are often described as “1/4-sheet” or " 1/2-sheet" sanders—referring to how much of a standard sandpaper sheet is mounted onto the oscillating pad. A 1/4-sheet sander has a roughly square sanding pad, while a 1/2-sheet sander has a rectangular shape. there are also many random-orbit sanders with round sanding heads. There are also a variety of detail sanders that also use random-orbit action. These usually have contoured, pointed sanding pads that accept specially shaped sandpapers that are usually affixed to the sanding pad with self-stick adhesives. If you had to choose only one type of sander to buy for home projects, it would most likely be a random orbital sander, as it is versatile, inexpensive, and easy to use. This type of sander is easier to wield than a rotary or belt sander because its action is more like vibration. Changing sandpaper is extremely easy, simply a matter of affixing the paper to the sander’s hook-and-loop surface. Many intermediate-level DIYers will find it useful to own two random-orbit sanders—a 1/4-sheet or 1/2-sheet model, plus a detail sander. Random-orbit sanders are typically corded electric tools, though there are some battery-powered units available. Prices start at around $50 and run up to hundreds of dollars. Most DIY homeowners will be satisfied with a moderately priced tool costing $75 to $100, which will be both highly functional and appropriately durable. Belt sanders are good for coarse removal of wood or finishes. When stripping a painted table, for example, the beginning stage will likely include belt sanding to remove the surface paint coat and reveal the wood beneath. Later stages will likely involve using a random-orbit sander to prepare the wood for a new finish. Unlike random orbital sanders, which cause the sandpaper to vibrate, a belt sander actually moves the sanding belt. This is a notable difference that you will appreciate when you need to sand down rougher areas. These are not good tools for detailed work, as it’s difficult to maneuver the sanding belt in tight spaces. Belt sanders come in many sizes, identified by the size of the sanding belt they use. The smallest belt sanders are generally 3 x 18 inches, but larger tools used mostly by professionals can be as large as 4 x 24 or 4 x 36 inches. Prices start at about $75, running up to about $300 for professional-level tools.
Handheld rotary/orbital sanders were once very common, but their popularity has waned now that excellent random-orbit sanders are so readily available. Like a belt sander, a rotary sander is best for coarse removal. A handheld rotary sander allows you to get close to edges, so it is often used in paint removal and refinishing work to strip edges before moving to a belt sander for larger areas. Stripping paint from wood lap siding, for example, often calls for a rotary sander to abrade the crevices where boards overlap. But like belt sanders, a rotary sander can be difficult to control, causing scores and gouges if you are not careful. Extensive use of a rotary sander is best left to experienced DIYers. Drum sanders are so powerful that they are capable of sanding off all sorts of materials that you want to be removed from your wood floor: bumps, gouges, stains, paint, adhesives, and mastic. Before sanding any flooring adhesives, test to make sure that they do not contain asbestos. Drum sanders should be used for solid wood flooring only. Do not attempt to use a drum sander on engineered wood flooring or non-wood flooring. Drum sanders are so powerful that they can rip through the thin top veneer of engineered wood flooring. Stationary sanders are used for precision sanding of woodworking project parts, where very fine tolerances are needed. These are not tools most DIY homeowners will want or need. But if you are a hobby woodworker, investing $100 to $300 in a basic table-mounted combination sander can make your hobby much more enjoyable.
For general DIYers, a good place to start is with a basic random-orbit sander—a square 1/4-sheet sander or round model. If you do a lot of furniture work, adding a detail random-orbit sander with a pointed, contoured head might be a good second tool to own.Many homeowners will find that owning a belt sander also makes sense, especially if you’re likely to strip paint or refinish tables from time to time. This is a great tool for coarse removal, though you likely won’t use it as often as your random-orbit sander.Rotary sanders are specialty tools, and while it can be convenient to own one, it’s usually easy enough to equip a standard power drill with a disc sanding head for occasional use. An exception is if you regularly repaint a house with wood lap siding, where it can be very helpful to own your own rotary sander.A drum sander for floor refurbishing is almost never worth purchasing (they can cost thousands). Instead, rent one when you need it.Finally, a stationary sanding station is a good choice if you build woodworking projects on a regular basis and need the precision provided by a stationary sander.
Whatever type of sander you buy, there are some features to look for that will make the tool easier, cleaner, and safer to use:
Dust bag: Sanding kicks up a lot of dust, so look for tools with good dust collection systems with built-in filters that can be cleaned or replaced. Make sure the dust bag attaches firmly, but that it is also easy to remove and empty. Some tools allow you to connect to a shop vacuum or other dust collection system using hoses.Variable speed: Cheaper tools usually run at a fixed rpm, but more expensive tools will give you an option of changing speeds. A good random-orbit sander, for example, may have settings that let you change speeds between 8,000 and 12,000 rpms.Dust-sealed switches: Cheaper tools often fail because switches quickly become clogged with sanding dust.Molded, padded handles: All sanders vibrate, and comfortable handles will make them much more pleasant to use over the long run.Balanced weight: Heft the tool in your hand. Better tools will be counterweighted and feel “right” in your hand—an important characteristic for long-term use.
