planer

A planer is a woodworking machine that removes thin shavings from a workpiece to produce a flat, smooth surface or to make one face parallel to the machine's bed. The tool works by forcing the wood against a rotating cutterhead mounted with sharp knives, usually two to four blades arranged around a cylindrical drum. The workpiece is fed either by hand (in a hand planer) or by motorized rollers (in a thickness planer or jointer planer), moving across the knives at a controlled speed and depth.

The most common industrial type is the thickness planer, a benchtop or floor-standing machine that accepts a board from one end, runs it under the spinning cutterhead, and ejects it from the other. The operator adjusts the cutting depth, typically from 1/32 inch to 1/8 inch per pass, by raising or lowering the bed or the cutterhead. Typical machines handle boards up to 12 or 16 inches wide, though industrial models can plane stock 24 inches wide or wider. The cutterhead rotates at speeds between 4,000 and 10,000 revolutions per minute depending on the machine class.

Hand planers, lighter and older variants, rely on the user to push the tool across the wood's surface. The plane iron (cutting blade) is set at a shallow angle in the sole (the flat bottom), and the operator applies downward and forward pressure to shave off a ribbon of wood. Hand planers are essential for fitting joints, trueing edges, and final smoothing where power equipment would be overkill or unsafe.

Common problems and setup

Planers commonly produce tearout when the grain runs against the direction of the feed, or when the cutterhead is dull. Dull knives leave a rough, sometimes fuzzy surface instead of clean shavings. Uneven planing results from a warped bed, misaligned rollers, or inconsistent stock thickness going in. Snipe, a shallow gouge at the ends of the board, occurs when the infeed or outfeed rollers lose contact with the wood. Proper maintenance, sharp blades changed or honed every 40 to 80 hours of use, and light cuts in the direction of the grain minimize these faults.

The planer sits between the jointer and the sander in a typical milling sequence. A jointer first flattens one face and one edge; the planer then makes the opposite face parallel and smooth; and the sander follows for final finish. The name derives from the action of the tool and the craft tradition: older terms include thickness machine and surface planer, but planer alone is standard in shops today.