Nautilus (Spiral) Gear Module

The Nautilus Gear Module is part of Mechlets, a modular system of mechanical machines that connect together and transfer motion from one module to the next.   This module uses a pair of non-circular nautilus gears to create a continuously changing relationship between the two rotating gears. Instead of maintaining a constant speed ratio like ordinary round gears, the changing radius of each gear causes the motion to speed up and slow down throughout each revolution.   The unusual gear shapes stay meshed as they rotate, making the changing geometry easy to watch. It’s a simple way to see how gear shape itself can be used to control motion—not just gear size or tooth count. Part of the Mechlets System The Nautilus Gear Module is an add-on module and needs a Mechlets input/driver to set it in motion. If this is your first Mechlet, visit the original Mechlets collection to download a: Thumb Slider or Thumb Scroller drive module Additional mechanical modules Splitters and connecting modules for building larger arrangements All Mechlets share the same mechanical connection, so modules can be combined, rearranged and driven together. Motion enters the Nautilus Gear Module from the connected Mechlet and drives the two visible gears. How the Nautilus Gears Work Ordinary spur gears are circular, so their effective radius remains constant as they turn. The Nautilus gears are different: their radius gradually changes around the gear. As the gears rotate, a larger-radius section of one gear meshes with a smaller-radius section of the other, and then the relationship gradually reverses. The result is a repeating change in rotational speed: slow → accelerate → fast → decelerate → repeat Even though the input motion is steady, the output motion continually changes speed. Because the gears are mounted in the open, you can watch the contact point move and see how the unusual geometry creates the changing motion. Fully 3D Printed The Nautilus Gear Module is designed around printed mechanical parts and snap-fit assembly: Two visible non-circular Nautilus gears Variable-speed gear motion Open mechanism for easy viewing Snap-fit retaining clips No screws No glue No bearings, motors or electronics The included assembly guide walks through gear installation, alignment and testing. Note: When the two nautilus gears are just touching by a single tooth, there is a chance for the gears to get out of sync. I believe this is caused by the the tolerance of 3d printed gears. Tolerance is the small amount of intentional clearance added between printed parts to compensate for printer accuracy and allow the gears to rotate freely without binding.