The Top That Deliberately Spins On Its Side

The Top That Deliberately Spins On Its Side

Most self-righting and tippe tops want to stand up on their stem.
This one does the exact opposite — on purpose.

When you give it a good spin, it searches for its own stable axis and settles into an elegant sideways spin on its edge. It doesn’t fall over after a few seconds. Instead it hangs there, calmly and almost meditatively balancing on its side. It looks different and feels different from any classic spinning top.

There are already countless models that rise onto the stem. That’s exactly why I deliberately chose this behaviour: a top that prefers the side as its equilibrium position.

Printing

• Material: PLA (recommended) or PETG

• Infill: 100 % (this is how the model was developed and tested)

• Weight: approx. 26.84 g at the default dimensions

• No inserts required — the top works without steel balls or extra weights

• Supports: not needed

The supplied dimensions (approx. 44 × 44 × 46.5 mm) are the tested default size. You can freely change them in the OpenSCAD code — the characteristic side-spinning behaviour remains stable across a wide range of sizes.

Freely Customize with OpenSCAD

The complete parametric OpenSCAD code is included.
You can modify, among other things:

• Overall diameter and height

• Stem length and thickness

• Shape of the lower spherical section

• Position and size of the internal chambers

Even after changing the parameters, the typical “balancing on the edge” behaviour should still work. Feel free to experiment — that’s what the code is for.

How It Works (Mathematics)

A rigid body has three principal axes of inertia with moments I₁, I₂ and I₃.
In a classic tippe top the centre of mass sits low enough that the stem axis becomes the stable rotation axis; friction and gyroscopic torques make the body rise.

In this design the mass distribution is intentionally chosen so that the stem axis is not the energetically preferred axis at high spin rates. Instead the rotation stabilises around an axis that is nearly perpendicular to the stem. The contact point migrates to the equator of the spherical section and the top finds a dynamic equilibrium there.

The behaviour is related to the intermediate-axis theorem (tennis-racket theorem / Dzhanibekov effect), where rotation about the axis of intermediate moment of inertia is unstable. Here that effect is used constructively: the top “escapes” from the stem axis and settles on its side.

In short:
Other tops want to stand up.
This one has decided to dance on its edge.

Happy printing and experimenting!