The physics behind the tippe top toy have been the subject of studies by scientists for years - dating back to the early 1890s. The tippe top is spun just like any other top, but pulls a surprise stunt. The top flips over and spins on its stem when given a strong twist. Why does the tippe top flip over? What does this mean for anyone planning to make one on a 3D printer?
Nobel Prize winners, Wolfgang Pauli and Niels Bohr, take a break with a
tippe top at the 1954 inauguration of the Institute of Physics in Lund, Sweden.
Early Top Patents
The first patent for the top, listed as “Wendekreisel”, was filed in Germany by Helene Sperl in 1891. While the patent seems to describe the top’s inversion property, reproductions of the top have proved unsuccessful. The patent expired after one year because the fee wasn’t paid.
During a trip to South America, Danish engineer Werner Østberg noticed kids spinning a small, round fruit. While spinning, the fruit would flip over (or invert) and spin on its stem for a short time. In 1950, Østberg filed a patent for his renewed design of the top and named it the tippe top. His design was a huge success, and he filed additional patents for it in multiple countries.
Why Does It Flip?
It’s not exactly a mystery… but the inverted spinning of the tippe top is intriguing. When the tippe top is spun at a high angular velocity with the stem pointing upward, the top begins to tilt downwards until the top spins on its stem.
Without diving into too much math and physics, here’s a simple explanation of why the inversion occurs when spinning a tippe top. When looking at the tippe top with the stem pointing upward, the geometrical center of the top is slightly above the top’s center of mass. This is partly caused by carving out the top part of the sphere around the stem.
Because the top’s geometric center and center of mass are not in the same location, the rotational axis is different from the geometrical axis. The difference in these axes causes the top to tilt over in an attempt to align the axes. The surface underneath the tippe top, and the friction that occurs at its point of contact, provides the necessary torque to flip or invert the top.
My Tippe Top Design
Using Tinkercad, I designed a three-dimensional model of a tippe top. Considering the 3D-printer’s printing surface, I chose to design my tippe top upside down - with the top of the stem resting on the print bed.
Bottom view of my tippe top model
Top view of my tippe top model
When printing an object on a 3D printer, you can choose the percentage of fill for the interior of the object. Usually a honeycomb or grid structure is created inside the object to hold it together. The higher the percentage of fill, the object’s mass will increase.
Fill and support structures seen while 3D printing a tippe top
Because the tippe top’s center of mass location is crucial to its operation, I tested out a variety of fill percentages and designs until I got the best inverted spinning results.
Iterations of my tippe top design to test its performance
My final 3D-printed tippe top design worked best when using a 90% fill or greater. This dropped the top’s center of mass low enough below the top’s geometric center to create the inverted effect while spinning.
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