fidget gear ring keychain spinner

I was asked once to add a key-chain attachment option to my rings (which you might want to check out, too) and here is the result. Actually it's the second version, it's nicer than the first. 

This model had it's debut at JRRF 2025 (Japan RepRap Festival, Tokyo) as giveaways to inspire and show the potential of 3D printing. It had some custom imprint that is of course not on the model for download here.

Even without attaching anything I often prefer this one over a ring, since the ‘lever’ adds some more ways to fidget with this thing. You can even emulate a clicky lever switch by pressing your thumb's fingernail into the outer indents, using it as the clicky spring (see last photo).

And of course you can attach keys or other stuff and spin it around. Be careful with that though to avoid hurting or damaging…

This ring also comes with slots for the turn tool, in case you have problems breaking it free, or if you want to use a power tool to break it in.

I uploaded 3 sizes; 16mm and 18mm are usually fine for teenagers and adults, 14mm is more suited for children. 

Printing: 

The 3mf files also are split into 5 parts for multi-color printing:

1. the sun gear (inner ring)
2. the main parts of the planet gears
3. the lower 0.38mm (two layers) of the planet gears
4. the upper 0.38mm (two layers) of the planet gears
5. the outer ring gear

You can choose colors depending on your hardware: If you have a printer with multiple heads or nozzles, you can color the whole planets (2,3,4) in a different color for example, but if you have a single nozzle color changer you can save a lot of filament swaps by only coloring the top and bottom layers (3&4) of the planets differently (4 color swaps - you can even do that manually, see description here).

General settings:

• I use 0.4mm nozzle and 0.17mm layer height
• random seam placement
• a bit of elephant foot compensation (say 0.2mm)
• I prefer NOT only one perimeter/wall on top layer
• 3 walls
• I also usually paint seams on the inside into one of the turn tool slots.
• Good bed adhesion is essential due to the small footprint.

This model requires a well dialed-in printer and filament combination; depending on these and the settings, the gears may

• rotate freely and quite smoothly right from the plate,
• need some force to break free,
• need some minutes of breaking in to run smoothly,
• be totally fused together.

If you have problems with fused gears:

• use force; if it breaks it wasn't usable anyway.
• try a different filament; some (like silk) are more prone to ooze and fuse than others.
• try reducing the extrusion multiplier/flow ratio a bit
• try a slightly negative XY size compensation (e.g. -0.02)
  (OrcaSlicer: negative for contour, positive for holes)
• try printing outer walls first
• try reducing acceleration and speed
• try reducing the temperature

Have fun!