ninja star fidget gear spinner

A ninja star (shuriken) combined with a planetary gear (like my gear rings ) makes a nice fidget spinner!

The tips are rounded off to avoid injuries - it's not actually for throwing! The 6 semi-holes between the 'blades' are big and rounded, thus finger-friendly for better fidgeting. The tips have some internal structures to add some weight and also to reduce stress and warping. This model comes in 2 ring sizes, 16mm and 18mm diameter.

Other fidget gear rings are available here .

---------------------------------------------------------------- Printing:

The 3mf files are split into 5 parts for easy multi-color printing.

- the sun gears (inner rings)

- the main parts of the planet gears

- the upper 0.38mm (two layers) of the planet gears

- the lower 0.38mm (two layers) of the planet gears

- the double outer ring gear

If you choose a different color for only parts 3 and 4, only 4 color changes are required, resulting in low filament waste with single-nozzle multi-color printers. Color changes can also be done manually (see 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

- 2 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.

- I also forced scarf seams on the outer part (part 5), countour, not smart, and painted them on some edge.

- In this print I also used Hilbert Curve at 80% as top infill for decorative purposes.

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, you can try:

- using force; if it breaks it wasn't usable anyway.

- a different filament; some (like silk) are more prone to ooze and fuse than others.

- reducing the extrusion multiplier/flow ratio a bit

- a slightly negative XY size compensation (e.g. -0.02) (OrcaSlicer: negative for contour, positive for holes)

- printing outer walls first

- reducing acceleration and speed

- reducing the temperature

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Have fun!