What Is the Purpose of a Jointer?

A properly adjusted and sharpened jointer will plane rough lumber smooth and true. Finished lumber can be accurately sized and squared.

Planing

The first application of a jointer is planing one surface of a rough board flat and straight. Even finished lumber that has been in storage will usually need adjustment by planing before use.

Squaring

If one face is smooth and perfectly flat, that face can be used as a reference point. Placed against the vertical fence of the jointer, one edge of the board can now be planed smooth and square to that face.

Thicknessing

Jointers can be used in conjunction with thickness planer attachments or stand-alone machines. Again with the trued face as a guide, the other surface can be planed to the required thickness.

Adjusting Width

Using the squared edge as the new reference, a uniform width can be marked on the board. Other tools may be used to remove most of the waste wood, and the last few passes can be made with the jointer.

Limitations

Because jointers cut with multiple blades set in a rotary head, pushing the work through the machine too quickly leaves a rippled surface. Jointers are also limited to lumber widths less than the width of the cutter head.

Resources

• Articles and Videos about Jointers