Which Leonardo da Vinci machine was designed to make a screw-shaped thread in wood?

Leonardo da Vinci designed a screw-cutting machine for producing screw-shaped threads in wood.

The machine was part of his studies of lathes and precision woodworking. A workpiece would be rotated while a guided cutting tool followed a controlled path along its surface. This arrangement could create a regular helical groove, the defining feature of a screw thread.

Leonardo was interested in mechanizing tasks that demanded repeated accuracy. Screw threads were valuable in presses, lifting mechanisms, vices, and other machines, but producing consistent threads by hand was difficult. A guided machine promised greater uniformity than an artisan working without a fixed template.

This design should not be confused with Leonardo’s general wood-turning lathe studies. A lathe rotates a workpiece for many purposes; the screw-cutting machine specifically coordinates rotation and tool movement to form a helix.