A wood planer is a tool used to flatten pieces of wood to make them even in thickness and completely flat on both sides of the piece. A traditional wood planer was a handheld tool, but more modern versions are electric and feature a planing platform that will adjust the thickness of the board accurately and quickly. This tool is sometimes called a thickness planer, and it can come in a variety of sizes, both in terms of height and width, and in terms of power output. Some machines are controlled manually, while others feature electronic controls for the most accurate cuts.
The wood planer works by feeding a board through the machine. While passing through the machine, the board is planed by a cutter head cylinder. The wood planer can only plane boards up to a certain size, depending on the size of the machine. Generally speaking, the larger the machine, the larger the planing surface will be, and consequently larger pieces of wood can be planed. The wood is fed into one side of the machine and is guided through the machine by a guide wheel. A second guide wheel or set of wheels is positioned after the cutting head to help the board progress all the way through the machine evenly and quickly.
One of the problems associated with using a wood planer is a condition known as "snipe." This occurs when part of the board is planed at a deeper angle or cut than the rest of the board. This usually happens when the board is fed into the machine incorrectly, leading the board to be cut at an odd angle. Snipe can be avoided by carefully feeding the board into the machine and making sure all components of the machine are in proper working order before using it to plane any wood.
One limitation of the wood planer is the need for a perfectly flat surface on one end of the board. By nature, the machine must have one flat reference side in order to plane the uneven side correctly. If both sides of the board are uneven, the side of the board being planed will be planed unevenly, since the other side of the board will cause the planer to come in contact with the board at an uneven angle. A hand plane can be used to create a more even surface on one side of the board if necessary.