A planer is a woodworking tool that shaves wood to a uniform thickness and leaves a smooth surface. Whether it’s a large stationary machine, a portable benchtop model, or a hand-held plane, the core job is the same: remove thin layers of wood so your boards end up flat, consistent, and ready to use in a project.
What a Planer Actually Does
A thickness planer takes rough lumber and makes it a precise, even thickness from end to end. Say you have a board that’s 1 inch thick on one end and 3/4 inch on the other. The planer shaves the high spots down so the entire board comes out at one consistent measurement. It also smooths the surface in the process, removing mill marks, rough patches, and minor imperfections.
This matters because store-bought lumber is rarely perfectly uniform, and rough-sawn wood from a sawmill is even less so. If you’re building furniture, cabinets, or anything where pieces need to fit together cleanly, every board in the project needs to be the same thickness. A planer gets you there quickly.
How a Thickness Planer Works
A power planer is more complex than it looks. You set the desired thickness using a crank or dial, place the board on a flat table, and the machine does the rest. Spring-loaded infeed rollers grip the wood and pull it into a spinning cutterhead, which shaves off a thin layer from the top surface. Outfeed rollers then push the board out the other side. The outfeed rollers are always smooth so they don’t mark the freshly cut surface.
Most consumer-grade benchtop planers can remove up to 1/8 inch of material per pass. For heavier stock removal, you simply make multiple passes, lowering the cutterhead slightly each time. Larger industrial planers use serrated steel infeed rollers for a stronger grip on thick hardwood, while smaller portable models use smooth rubber-coated rollers.
The cutterhead holds two or three blades (sometimes called knives) that can be high-speed steel or carbide-tipped. High-speed steel works well for softwoods and general use. Carbide blades cost more but last roughly 8 to 10 times longer, making them worth the investment if you regularly plane hardwoods or exotic species.
Planer vs. Jointer
One of the most common points of confusion is the difference between a planer and a jointer. They’re partners in a two-step process, and neither can do the other’s job.
A jointer flattens one face of a board and squares one edge. It removes warps, twists, and cups so you have a reliable reference surface. But a jointer can’t make a board a consistent thickness. If you flip a jointed board over and run the other side across the jointer, both faces will be flat, but the board might be 3/4 inch thick on one end and a full inch on the other.
That’s where the planer comes in. You place the jointed face down on the planer’s table, and the machine cuts the opposite face parallel to it. The result is a board that’s flat on both sides and the same thickness everywhere. The jointer goes first, the planer goes second. Skipping the jointer means the planer will simply reproduce whatever warp or bow exists on the bottom face, since it references off whatever surface is sitting on the table.
Types of Hand Planes
Before power planers existed, all of this work was done with hand planes, and many woodworkers still prefer them for fine work. Hand planes come in a wide range of sizes, each suited to different tasks.
- Block plane: A small, one-handed tool for chamfering sharp edges, trimming end grain, smoothing small pieces, and cleaning up joints. It’s the plane most woodworkers reach for first.
- Smoothing plane: A medium-sized bench plane (typically a No. 4) used as a final step to produce a glass-smooth surface before finishing. It removes very thin shavings and can leave a surface that needs no sanding at all.
- Jack plane: A versatile mid-sized plane (No. 5 or No. 6) that handles rough stock removal, flattening panels, shaving doors that stick, and jointing edges for glue-ups.
- Jointer plane: The longest and heaviest bench plane, designed to flatten long boards and straighten edges. Its length bridges dips and high spots, producing a truly flat surface.
- Specialty planes: Shoulder planes fine-tune tenons and rabbets. Router planes cut precise shallow mortises for hinges and inlays. Chisel planes reach into tight corners to trim flush.
Handheld Electric Planers
A handheld electric planer is a different tool from both a hand plane and a stationary thickness planer. It’s a construction-trade tool, built for jobs like leveling floor joists before laying plywood, trimming a door that won’t close, or knocking down a high spot on a rafter. It removes material fast but without much precision.
Some woodworkers find handheld electric planers useful for boards that are too wide for their benchtop planer or too short to safely feed through a machine. (Boards shorter than about 12 inches can be dangerous in a thickness planer because the infeed and outfeed rollers can’t grip them securely.) But for furniture-quality work, the handheld electric version is generally too aggressive and imprecise.
Grain Direction and Tearout
The single biggest factor in getting a smooth surface from any planer is feeding the wood in the right direction relative to the grain. Wood fibers lay at a slight angle inside the board, like overlapping shingles. Cut with the grain and the blade slices cleanly. Cut against it and the blade lifts and rips fibers before it can cut them, leaving a rough, chipped-out surface called tearout.
To figure out the right feed direction, look at the edge of your board. The grain lines will angle toward one face. Feed the board so the blade meets those angled fibers going “downhill” rather than digging under them. If the grain switches direction partway through the board, go with the majority. With a hand plane, you can simply stop where the grain reverses and plane from the other direction.
When tearout is unavoidable, taking lighter passes helps. The less material the blade removes per pass, the less chance it has to rip out fibers. On a hand plane, using a higher cutting angle (around 55 degrees) also reduces tearout in tricky grain. For boards with truly wild, unpredictable grain, a card scraper often works better than any plane.
Dealing With Snipe
Snipe is a shallow gouge that a thickness planer leaves at the very beginning or end of a board, where the rollers momentarily lose full pressure. It’s the most common frustration with benchtop planers.
You can minimize snipe by adjusting the planer’s infeed and outfeed table extensions so they sit perfectly flush with the main bed under the cutterhead, then raising the outer edges very slightly. Supporting the board as it enters and exits the machine also helps. Many woodworkers simply cut their boards a few inches longer than needed and trim off the sniped ends afterward.
Safety Basics
Planers are loud and produce a high volume of chips. Hearing protection and eye protection are non-negotiable. A dust collection system or at minimum a shop vacuum connected to the dust port keeps your workspace breathable and your planer running efficiently, since chip buildup can cause feeding problems.
Never feed boards of different thicknesses through a planer at the same time. The thinner board won’t be held securely by the rollers and can be kicked back at high speed. Avoid stock with large knots, cracks, or splits, which can catch on the cutterhead and cause dangerous kickbacks. Keep the blades sharp: dull knives require more force, increase the chance of kickback, and leave a poor surface. Stand to the side of the planer rather than directly behind it once the board is feeding through, so you’re out of the line of fire if anything goes wrong.