The jointer is a long plane (between 50 and 70 cm) that has a large contact base (called sole) with the wood on which it slides. The length of the plane greatly affects the precision of the flattening of the wood to be worked. A plane with a very short support base sliding on an irregular board eliminates the excess material, reproducing however the imperfections of the board. To obtain a precision flattening and leveling, a jointer is therefore necessary.