What type of saw is specifically designed for cutting metal?

The hack saw is specifically designed for cutting metal due to its fine-toothed blade and sturdy construction. This saw features a relatively thin blade that is tensioned within a frame, allowing for better control and precision when cutting through harder materials like metal. The teeth of a hack saw are typically designed to cut on the push stroke, which is effective for slicing through various thicknesses of metal.

In contrast, the other saws mentioned, such as the crosscut saw, keyhole saw, and back saw, are intended for woodworking and are not suitable for metal cutting. The crosscut saw is used primarily for cutting across the grain of wood, the keyhole saw is designed for making interior cuts in wood, and the back saw is used for precise cuts in woodworking. None have the appropriate blade or design necessary for effectively cutting metal, making the hack saw the clear and correct choice for this purpose.