What type of machine did Leonardo da Vinci design to cut the threads of screws?

Leonardo da Vinci designed a screw-cutting machine to produce the threads of screws.

Screw threads require a controlled relationship between rotation and forward movement. Leonardo’s concept addressed that problem with coordinated mechanical parts intended to guide a cutting tool along a rotating workpiece. Producing uniform threads was an important step toward more precise mechanical construction.

The design reflects Leonardo’s broader interest in machine tools. His notebooks include studies of gears, drills, lathes, and other devices that could make workshop production more consistent and less dependent on hand skill alone.

A screw-cutting machine is not simply a drill press. A drill makes holes, while a screw-cutting machine forms a helical thread. It is also more specific than the general term lathe, which can describe many turning operations.