What machine did Leonardo da Vinci design to wind thread onto spools automatically?

Leonardo da Vinci designed an automatic bobbin winder to wind thread onto spools.

The machine was part of his interest in improving textile production. Bobbins need evenly wound thread so that they can be used efficiently in later stages of weaving or textile work. Leonardo’s mechanism used coordinated motion to guide thread and rotate the receiving spool, reducing the need for repetitive manual winding.

The design reflects a major theme in Leonardo’s engineering notebooks: replacing inconsistent hand labor with controlled mechanical movement. He studied gears, cams, pulleys, and rotating shafts in many contexts, including manufacturing machinery.

The bobbin winder should not be confused with a spinning wheel. A spinning wheel creates or twists thread from fibers, while a bobbin winder places already-produced thread onto a spool. Leonardo’s design also belongs to textile machinery rather than to his better-known military or flying-machine studies.