Magnetic Levitating Spinning Top

A 3D Printed Magnetic Levitating Spinning Top (Levitron)

(click on the pictures to enlarge)

This amazing toy (Levitron - Wikipedia) caught my attention a long time ago. This is the kind of experiment that just watching from videos was not enough to satisfy me so I decided to take the challenge of build one. On the very first attempt, I discovered that the challenge was going to be huge! At this occasion, of course, I did not succeeded and was very far to even understand what I was doing wrong. I did a lot of research and watched several videos until start understanding what I was supposed to do. I gave up several times and returned back the same many times, inspired by several videos shared by people that succeeded. After making at least 4 prototypes and persisting a lot, finally, I could get a satisfactory result. Below, let me share the final version of this experiment.

Magnets:

All the project was designed using 30mm (diameter) x 3mm (thickness) neodymium magnets. They are easier to find and stronger them ferrite magnets.

The spinning top:

Used a single 30x3mm magnet. 3D printed the top and bottom in two separate parts to be glued to each side of the magnet. The upper side, allows the addition of washers to fine tune the spinning top´s weight.

The Base:

Used 12 30x3mm magnets (2 on each hole). The base is consisted of the main section where all magnets are attached under pressure and a cover to protect them from the bottom.

Supports:

Most of the homemade Levitating Spinning Tops I found, used very improvised methods to adjust the spinning top height. All commercial and homemade Levitating Spinning Tops requires the user to rotate the spinning top manually by holding its spindle. I created a base with appropriate height and an apparatus to make rotation easier and repeatibility more consistent.

STL files:

Top1.stl

Top2.stl

Base1.stl

Base2.stl

Support1.stl

Support2.stl

Video:

Tips and Lessons Learned (Practical Guide):

1) It is better make the spinning top with neodymium magnets. They are stronger than ferrite magnets of the same weight/volume. This allow the spinning top to levitate higher.

2) Use neodymium magnets on the base allows you to make it lighter and thinner.

3) There is a good relationship between the spinning top diameter and the inner diameter formed by the 6 magnets positioned as a circle in the base. If the inner diameter is closer or smaller than the spinning top diameter, it will never be attracted in the middle. If the inner diameter is too big, the spinning top will not levitate at a given height. I can't tell I reached the best relation because I did not make an adjustable apparatus and also did not made several different bases to test this. All I can say is that 5mm difference matters in the final result. Now, I´m using a 30mm diameter spinning top and a base with ring inner diameter of 50mm.

4) Neodymium magnets break and scratch easily. I lost 3 of them. I gave up of making a base that shows out them. Instead, The base and the spinning top encloses the magnets in order to protect them as much as possible against hits between the spinning top and the base.

5) The spinning top must be designed to receive washers of different weights and materials. In the end, even a plastic washer may be needed to calibrate the weight.

6) I read that spinning top rotation must be between 1000 and 3000 rpm. I did not measure these values myself but can confirm that more speed don't mean more time levitating. In fact, if you apply to much speed (and this is easy task with the apparatus I made to rotate the spinning top), it will go off on a tangent just like on the first attempt of the above video. Here I must also comment that spinning top rotation speed is not low like you may think after watching the videos. Have in mind that stroboscopic effect from the video fps (frames per second) causes the spinning top looks slower than it really is.

7) If you use the project I shared, you will just need to take care of the spinning top weight calibration and base tilt. Otherwise, my suggested steps to start from scratch are:

7.1) Define the spinning top´s magnet and make it.

7.2) Choose the base's magnet. It's magnet inner diameter must be bigger (but not too much) than the spinning top diameter.

7.3) Magnets from the spinning top and base must face with the same magnetic pole so they repeal each other if you position the spinning top over the base ring. Over the base ring, I mean, is for instance, over one of the 6 magnets from the base arranged as a circle.

7.4) If base magnet inner diameter is good, when starting pushing down the spinning top on the center of the base magnetic ring, you will also feel a repulsion force but as soon as the spinning top gets closer to the base, the force will become null and later, the base will start attracting the spinning top instead of repeal it. Make sure to find the height a millimeter below the point where force is null. As this point force is of attraction and it is at this point that you should start the spinning top rotation. If you try rotate over this limit, the spinning top will fly away. If you try rotate below this limit, the attraction will not allow rotation and the spinning top will quickly precess and drop. Note that magnetic forces wants to rotate the spinning to make it face down. It is the gyroscopic force that will prevent this.

8) If you are using this project files or followed the instructions from step 7, you are ready to play. Here you will need:

• Patience to not give up. Instead, acquire practice to rotate the spinning top over the magnetic field.
• Knowledge to understand what is going on and make the necessary calibrations.

Calibration and fun:

1) Height from the base: Learn how to rotate the spinning top over the base at a height mentioned on the item 7.4. This height is the very first parameter you must be sure is correct. If it is, the spinning top will rotate freely and any precession will be fixed by the magnetic field. Please refer to item 7.4 to see what happens if you are below or above this limit.

2) Spinning top weight: Now that your spinning top is rotating at the height mentioned on the previous item, it is time to start increase this height by lifting the support where the spinning top is rotating. This will make the spinning top leave the position where it is being lightly attracted to the position where the interaction to the base is null and right after, to the position where repulsion starts happening. Two things may happen when repulsion starts. If the spinning top is too light, if will jump away from the support. If it is too heavy, the repulsion will not be strong enough to make the spinning top detach from the support. My suggestion here is make the spinning top heavy and start removing weight until you see it detach from the support. Trust me, this is more conclusive as to much weight is the only reason why the spinning top does not levitate at this moment. If it flies away there is other reason than just the spinning top be too light. Remember that there is a really fine tuning here. steel washers may don't provide the expected granularity. Eventually, you may have to add washes made of plastic or duct tape and start removing them to achieve the expected result.

3) Base tilt: If you followed my advice by making the spinning top heavy and removing its wight instead of starting with a light spinning top and adding weight to it, now you are sure that your spinning top is as heavy as possible. Any weight you add to it will cause it to not detach from the support. So, why are still seeing it fly away from the sides or from a given side? Since you are sure it is not due to the spinning top weight (too light), you can be sure that the problem is the base. It is time to start adjusting its tilt by adding some sheets of paper on the base´s support. Note that the base has 3 supports (3 points define a plane) and you should play with them to adjust the tilt. Again, this is very sensible process and a single sheet of paper under one or two supports may be the difference.

Now that tilt is correct, the spinning top will not fly away. Instead, if will be locked levitating over a magnetic field. I could achieve on this project, 5cm height levitation for around 3min.

Have fun!