What Leonardo da Vinci machine used rollers to flatten metal into sheets?

Leonardo da Vinci’s rolling mill used opposing rollers to flatten and shape metal into sheets.

In a rolling mill, metal passes between rotating cylinders. The gap between the rollers applies pressure and reduces the material’s thickness, producing a more uniform sheet than repeated hammering alone. Leonardo’s drawings show geared mechanisms for turning the rollers and controlling the workpiece.

Metalworking was important to Renaissance architecture, weapons manufacture, tools, and decorative arts. Leonardo studied machines that could deliver controlled force, including presses, cranes, mills, and devices for drawing wire. His rolling-mill concept reflects his interest in replacing irregular manual effort with repeatable mechanical motion.

The machine should not be confused with a printing press, which transfers ink to paper, or a forge, which heats and shapes metal. Leonardo’s design belongs to the history of metal-forming machinery, although surviving evidence does not establish that his exact model was constructed.