Wood is a beautiful material that is relatively easy to work with and has some amazing properties. One of the disadvantages to wood, however, is that it expands, contracts, cups and warps in different conditions. In this sense, it is not as stable as stone or most metals. To begin a woodworking project, a woodworker usually starts with rough lumber and must go through various steps to ensure that it is flat. Some woodworkers prefer to use handtools only, but for those that use power tools, a jointer is typically used.

The majority of warping and splitting of wood occurs after it is cut out of the log and dried. Each board will continue to move throughout its life as temperatures and humidities change. When a woodworker purchases wood from a lumberyard it is rarely flat and smooth and special tools are required to prepare the wood for use in projects such as furniture.

As shown in the photograph below, a jointer includes infeed and outfeed tables. A set of rotating blades is positioned between these two tables. A fence is set on one side of the jointer to serve as a guide. The infeed table and outfeed table are adjusted so that they are close to parallel, but the infeed table is slightly lower, thereby exposing a small amount of the cutting blades. The woodworker then presses the lumber against the infeed table and pushes it onto the outfeed table; the rapidly spinning blades remove a small amount of material. If the wood is particularly warped, several passes on the jointer may be required.

After a sufficient number of passes on the jointer, one surface of the wood is flat. The process usually continues with a thickness planer, another specialized power tool that removes wood from the opposite face of the board. A few passes through a thickness planer creates a board that has two flat and parallel face.

Next, the woodworker usually takes the partially surfaced board back to the jointer to square up the edge. In this instance, the board is placed vertically against the fence. A few passes may be required to get a flat edge that is square to the two faces. The remaining edge is usually squared up on a table saw.

The fence on most types of jointers can be adjusted to various angles. By adjusting the fence in this way, a jointer can also be used to create chamfers along the edge of a board.