What machine did Leonardo da Vinci design to manufacture screws more consistently?

Leonardo da Vinci designed a screw-cutting machine to manufacture screws more consistently.

His mechanical studies included a lathe-like device with gears that could guide a cutting tool along a rotating workpiece. Such a mechanism would help produce regular threads instead of relying entirely on hand work.

Consistent screw threads were valuable because they allowed matching bolts and nuts to fit reliably. Leonardo’s design belongs to a broader group of machine-tool studies in his notebooks, where he analyzed gears, force, and controlled motion.

The drawing should not be treated as proof that Leonardo invented the modern industrial screw-cutting lathe. Later engineers, including Henry Maudslay in the late eighteenth and early nineteenth centuries, developed machine tools capable of precise standardized production.