A lathe holds the workpiece. The laser does the cutting. Nothing touches the metal except light. Rotary fibre laser cutting merges two machine architectures. A chuck and tailstock spin the tube on a driven A axis, exactly as a lathe would, while a linear Z carriage traverses a cutting head along the length. Instead of a carbide insert plunging into the material, a 1.06 micrometre fibre laser beam focuses to a spot around 30 to 100 micrometres across, delivering irradiance in the region of 10 megawatts per square centimetre. The steel does not shear. It vaporises and blows clear. The mechanics of the cut are worth unpacking: - Absorption at 1.06 micrometres is far higher in steel and aluminium than the 10.6 micrometres of legacy carbon dioxide lasers, which is why fibre sources displaced them for metal - A coaxial assist gas jet, nitrogen at 15 to 25 bar or oxygen at lower pressure, ejects the molten kerf material downward - Oxygen adds an exothermic iron oxidation reaction, accelera...