Saw

A saw is a tool used to cut materials such as wood, plastic, or, with specially designed blades, metal. Its main part is a toothed blade with many small cutting edges. When the saw moves back and forth, or when the blade moves continuously in one direction, its teeth gradually remove small amounts of material and create a cut called a kerf.

Unlike a knife, which generally cuts with a relatively continuous edge, a saw divides the material through the repeated action of many teeth. The shape, size, spacing, and hardness of the teeth vary according to the material and the type of cut required. Some saws are operated by hand, while others use an electric motor. Different saws are designed for different tasks.

A hand saw is commonly used for cutting pieces of wood, while a hacksaw has a fine-toothed blade suitable for cutting metal and some other hard materials. Circular saws use a rotating toothed disk, and band saws use a continuous toothed blade that runs around wheels. The teeth may be arranged in different patterns to make cutting faster, smoother, or better suited to a particular material.

During sawing, friction produces heat, and the removed material forms sawdust or small chips. The cut is usually wider than the thickness of the blade because of the arrangement of the teeth. Safe use requires keeping hands away from the cutting path, securing the material firmly, and choosing a blade appropriate for the job.