Before two boards can be joined they must have perfectly straight edges. That's where a jointer comes in. It's the tool of choice for smoothing edges or cutting corners.
The jointer has a fence for guiding stock through its blade. The fence can be adjusted to cut angles or bevels. The blade is surrounded by an in-feed table and an out-feed table. The in-feed table must be level with or lower than the out-feed table, or the blade won't make contact with the wood. A guard covers the blade to protect the user's hands, and an adjustable depth gauge sets the depth of the cut. Cuts should be no deeper than 1/8 inch per pass.
To use the jointer to smooth edges, feed the wood into the tool with the rough edge facing down. Feed the wood through the jointer as many times as needed to achieve a straight edge. This process is useful for straightening a warped board.
To use the jointer for planing, use a paddle or push-stick to push the wood through the blade with the rough edge facing down. Use this technique to carve imperfections out of wood.
To make a bevel cut with a jointer, adjust the fence to a 45-degree angle. Tighten the fence and lock it into position. Feed the wood through the blade, with the edge to be cut facing down. Several passes may be needed to create the bevel.