Machine for miter-cutting of metal structure for subsequent folding at 90 degrees and can form easy-weld structures and perfect presentation. The positioning of saw groups can be manual or automatic and programmable. The pieces fastening is by hydraulic clamps, as well as the cutting groups advance. Each of the machining sides has two saw groups addressed to 45 degrees so that both cut 90 degrees which subsequently allow to the folding angle. The cut at 90 degrees in the two parts occurs simultaneously thereby achieves a high production. The tool lubrication by oil mist.