What Leonardo da Vinci invention helped a machine wind thread onto a bobbin?

Leonardo da Vinci designed an automatic bobbin winder to place thread onto a bobbin efficiently.

The mechanism was part of his interest in textile manufacturing and repeatable industrial processes. A bobbin stores spun thread or yarn, and winding it evenly is important for later weaving or further spinning. Leonardo's design used coordinated mechanical movement so that the thread could be wound in a controlled pattern rather than by constant manual adjustment.

The invention is sometimes described as an automatic machine because it reduced direct hand labor, although it still required a source of power and supervision. It belongs to the same broader tradition of Renaissance machines that used cams, gears, and rotating shafts to automate repetitive actions.

It should not be confused with a spinning wheel, which twists fibres into yarn. A bobbin winder handles already formed thread; it does not perform the main spinning operation.