Tiger Stripe Spinner (No Supports or Assembly)

This is my second model of a spinning battle top. It uses the same custom handle with a gear rack ripcord, focusing on ease of printing, ease of use, and essentially no assembly needed. Just print and enjoy! The drive gear is separated from the main body to facilitate no supports needed. Both the gear and the main spinner body have printed threads so you can lock in the gear and get spinning! There are two size ripcords to that you can even print every part of this on a Prusa Mini. 

The spinner is held in place when it gets up to speed by the rack. As soon as you finish the rip, the spinner drops on the ground and starts attacking. I added support ribs inside and increased the external wall fills. If you print full infill, the moment of inertia is maximized with a weight far off-center. Plus you have an extra ballast in the base keeping you upright. Give it a whirl and enjoy!

Contest Note

The ripcord is short enough to satisfy the max length allowed. As seen on the drawing image, the blade height is centered on the 25mm height requirement. Go ahead and take it for a spin!

Note on printing:

The spinner was designed with intentional pockets. The center of gravity position is assuming a uniform density (100% infill, same material top/bottom) print. If you stray far from solid infill (below 80% or so), all bets are off on center of mass placement. The high-density ballast bringing down the center of mass is pivotal (pun intended) for surviving impacts and remaining upright. The heavier your spinner is, the better is will hold up to competitors.

Mechanics Explanation:

A spinner by itself is an unstable object on an unstable base. Spin it quickly, though, and the gyroscopic effect keeps it upright. The best battle spinner will have a low center of mass for stability and a high moment of inertia for resisting impacts. To have a high moment of inertia, (I = m*r), you can increase either mass (m) or the offset from center (r). A solid ring at the maximum radius helps increase the moment of inertia while the cutouts coupled with the solid-core base helps keep the center of mass slightly lower. Both of these design elements are highlighted on the drawing and one of the reasons to spend a little bit more filament to make your spinner beefy!

Multi-body printing:

For the spinner itself, there are three parts. The first is all of the geometry in one body, the second is the spinner base body, and the third is the spinner ribs. If you want to print multi-material as shown in the images, use the second and third bodies in your slicer; if you want the quick prototype or single-material design, just use the first body like I did in the initial images. Happy printing!

Remix Friendly Base:

Check out the base part .stp if you're interested in remixing with your own spinner idea. It is a basic cylinder (with the right thread profile) that can be pulled in to your CAD software of choice and built on as a base!