You don’t have to use every single grit as you sand your way from coarse to fine. Instead, use every other grit; 80-120-180 or 100-150-220, for example.
Connecting to a vacuum doesn’t just cut down on dust. It actually allows your random orbit sander to work faster. Even with the sander’s built-in dust collection system, the sander rides on a thin cushion of dust that prevents full contact between the grit and the wood. So, by increasing dust removal, a vacuum improves sander efficiency. On some sanders, hooking up to a vacuum doubles the sanding speed.
For faster hand sanding, you just press harder and move faster. But with a random orbit sander, that strategy will actually slow you down. Too much pressure or speed creates tiny swirling scratches that you’ll have to sand out sooner or later (often later, after stain makes them visible). A light touch and patience are the key to avoiding those swirls. Just rest your hand on the sander; don’t press. The weight of your arm provides enough pressure. Move at a snail’s pace; no more than 1 in. per second. Going that slow feels unnatural and takes some self-discipline. So try this: stretch out a tape measure along your project and watch the second hand on a clock while you sand. After about 30 seconds (or 30 in.), you’ll get used to the right speed.
How smooth is smooth enough? We put that question to professional woodworkers—and couldn’t get a straight answer. (Woodworkers are notoriously noncommittal.) “It depends...” was the typical response. Here’s what that means:
“Open-grain” woods like oak and walnut have coarse grain lines and a rough texture. So sanding to very fine grits is a waste of time. “Closed-grain” woods like maple and cherry have a smoother, more uniform texture. So they need to be sanded with higher grits before the sanding scratches will disappear.
The finish matters too. For thick coatings like polyurethane, varnish or lacquer, most of the guys we talked to stop at 150 grit on open grain woods, 180 on closed. For oil finishes, which don’t create much buildup, higher is better; 220 on open grain, 240 on closed.
A 5-in. random orbit sander is the essential sanding tool for any DIYer. If you’re a serious woodworker, you’ll also love a 6-in. version. An extra inch may not seem like it would produce a big jump in sanding speed, but it means almost 45 percent more sandpaper surface, plus a more powerful motor. Sanding faster comes at a price, of course: Six-inch sanders are two to three times more expensive than five-inchers, and the larger sanders are a little harder to control, especially on vertical or narrow parts.
Before cutting up boards for your next project, sand them all with 80- or 100-grit. You might waste a little time sanding areas that will end up as scraps, but you’ll come out ahead in the long run. The initial sanding—removing scratches, dents and milling marks—is the heaviest sanding. And if you sand boards before cutting or assembly, you can use the tool that does deep sanding fastest: a belt sander. Sanding whole boards also eliminates the repetition of stopping, starting and setup for individual parts.
Sanding Syndrome is a psychological disorder caused by fussy attention to detail combined with brain-rotting boredom. Symptoms include drooling on the project, hearing voices in the whine of a belt sander and seeing cartoon characters in wood grain patterns. There’s no sure way to prevent Sanding Syndrome, but a little entertainment helps. Earmuffs or earplugs with built-in speakers block out power-tool noise while reducing boredom. Search online for “stereo earmuffs” or “noise isolating earbuds” to browse a huge selection. Prices range from $25 to $200.
Gang sanding with a random orbit or belt sander lets you smooth a bunch of edges in one pass. As a bonus, the wider surface prevents the sander from grinding too deep in one spot or tilting and rounding over the edges. This trick also makes sanding a self-correcting process; all the parts will end up exactly the same.
The first commandment of sanding: Sand with the grain. But when you have a lot of wood to grind off, break that rule and run your belt sander diagonally across the grain (at about 45 degrees). Instead of scratching away at the wood fibers, the belt will rip them out. It’s incredibly fast—and dangerous. Be careful not to gouge too deep, and expect to follow up with some heavy sanding to smooth the “plow marks” left behind.
Better sandpaper has sharper particles of grit, which bite into wood faster. And not just a little faster—a lot faster. Premium paper removes wood at two or three times the rate of standard paper. It costs a bit more, but the grit stays sharp much longer, so you actually save money, whether you’re using sheets, discs or belts. Norton 3X, 3M SandBlaster and Gator Ultra Power are three common lines.
Glue spots are cruel. When you think all the tedious sanding is done and you apply stain or even varnish, they’ll appear like bleached smudges. Getting rid of them means more sanding. On a flat surface, glue drips aren’t a big deal. You’ll remove them automatically as you run through the normal sanding process. But in hard-to-sand spots like inside corners, prevention is the best strategy, and a little masking tape will save you a lot of hassle.