Herringbone Gear Desk Fidget

thingiverse

I created this Thing as a fun little project to fill my spare time with design and printing, gaining the added benefit of being able to display it on a desk and play with it. This Thing is simply a basic 2:1 gear ratio - for every one revolution of the large (driven) gear, the small (driving) gear makes two revolutions. I designed this using herringbone gears because they are easy to mesh and self-align. Standard spur gears tend to wander without some method retaining them, and helical gears have axial loading that will also cause them to move if not retained. For ease of 3D Printing, herringbone gears work perfectly. I've also included the Fusion360 files needed to modify this if you'd like or to see how I've designed these. (Hint: I made use of the Spur Gear Add-in in Fusion360) 1. I printed these with zero top/bottom layers and honeycomb infill because the printing is faster and it's just as strong. I recommend at least 2 perimeters/walls. 2. I printed the gears at 0.16mm layer height and everything else at 0.24mm layer height. 3. Depending on your layer change settings, you may get a seam or a blob in the gear teeth that hinder meshing. If you print in PLA, this should wear down after a few rotations of the gears. 4. I added through holes in the shafts near the gear to allow you to put a screw, pin, or other method to keep the gears from moving, but it won't be an issue. 5. I prefer the toy without the crappy crank handle, but I added it for a friend. I just use a wire-tie through the holes to tie them together. It's not pretty, but it works. 6. Added bonus: Use a paint marker to mark on the gears where they mesh and watch the gear ratio as you turn it and it takes 2 rotations of the small gear to get the marks to line up again!