Change the shape, dimensions and materials. Watch the top change, then see what happens to mass, moment of inertia, centre of gravity and rotational energy.
No account. No ads. No pretend precision. The physics is an engineering estimate from the geometry you create.
Choose a starting shapeFull side-profile families
Body
Stem / handle
Visible handle above body:
Tip and balls
Live physics
3000
0.00Estimated mass g
0.00Spin MoI ×10⁻⁶ kg m²
0.00CG above tip mm
0.00Radius of gyration mm
0Rotational energy mJ
0.00Angular momentum mN m s
0Mass in body %
0k / body radius %
Move a control and the explanation will follow the design.
These are comparative engineering estimates from an axisymmetric model, not certified measurements. The 10.5 mm lower insert is shown entering the body, while its hidden insertion depth is not yet included as a separate mass replacement. Real spin time also depends on balance, surface finish, aerodynamic drag, tip condition and the launch.
Workshop examplesFour real Desire3D tops used while developing the model
Spinning top physics
What actually changes when you redesign a top?
A spinning top is a small machine for storing rotational motion. Two tops with the same weight can behave very differently if one carries more of its mass near the outside edge while the other concentrates it near the centre.
Moment of inertiaHow strongly the rotating mass resists a change in rotational motion. Moving mass farther from the axis usually increases it.
Centre of gravityThe balance point of the complete top measured here above the spinning tip.
Radius of gyrationA compact way of describing how far from the axis the mass is effectively concentrated.
Rotational energyEnergy stored in the spinning top at the selected RPM. It rises very quickly as speed increases.
Does a heavier spinning top always spin longer?
No. More mass can help store rotational energy, but mass alone is not the answer. Distribution of mass, balance, tip friction, air drag and the quality of the launch all matter. A badly balanced heavy top can lose energy far faster than a lighter, well-made one.
Why wide tops can feel different
Increasing diameter can move material farther from the spin axis. That can raise moment of inertia even without a dramatic change in total weight. Use the builder above and watch the MoI and radius of gyration values as you alter width and profile.
Metal, wood and 3D printed spinning tops
Density changes the design quickly. Brass, bronze, steel and tungsten pack much more mass into the same volume than aluminium, hardwood or common printing plastics. The material library here is deliberately broad so the builder can be used as a design and learning tool, not just as a catalogue of parts we currently make.