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The magnitude of the centrifugal forces, (red arrows), determine the speed of the precession, and not its direction. The direction of the precession is at 90° from the direction of the torque, whatever the magnitude of the torque. The torque in the video stays always on a vertical plane so the direction of the precession happens always on the horizontal plane, so the height never changes. If the torque, (red arrows), is stronger, this would make the precession faster, and, in turn, this would make the nutation slower. But the direction of the precession would not change.

This is not easy to explain in a few words. You can find it at 21:58 in the video; the red arrows are the forces that cause the precession. The gyroscopic effect turns these forces into tilting motion with a 90° delay, so the movement could be expected to be like in the sequence 2. Anyway it must be considered that, while the disk tilts, the direction of the red arrows, (centrifugal force), changes. Consequently, the position of the blue arrows, (direction of the tilting movement), changes too. There is a reciprocal feedback between the two things so the direction of the tilting motion changes continuously. So the motion does not happen like in the sequence 2, but like in the sequence 3. The result is that the orbits rotate at a constant height.

Thank you. Sometimes I like to experiment with different mediums. Spin times are not the only reason of interest for making tops.

Thank you. Yes, it's original. Maybe no one has ever used sea urchin shells before, for making tops.

The difference is about the speed of the nutation. At the left, the object nutates faster that the spin speed. At the right, the object nutates slower than the spin speed. I see that you make questions, from time to time. Could I know the reason, maybe you are a student of physics ? Or, it's just your personal interest ?

@@iacoposimonelli7191I'm sorry . I read in class 9 . as a bangladeshi , English is my second language and i am very weak in english . that is why I ask question frequently.

@@raihanaa1614 , don't worry, if you need to make other questions, feel free to ask, I will be glad to answer.

That's the superposition of two different movements, a precession, (torque induced precession), and a nutation, (torque free precession). In the following sequence you can see the two movements isolated, and, at the right, the two movements superposed: ruclips.net/video/mSmUpdKu6h0/видео.html

I am not sure to understand your question, but I try... The movement at 5:19 is not possible by inertia alone, without any applied force. But in a three-dimensional object, during the torque free precession, the symmetry axis makes just that movement. For example, in the sequence starting at 12:12, you can see the symmetry axis, (the one with pink color, which in the video I also called third principal axis of inertia), making that "impossible" movement. It can do so, because it is pushed by the other two axes which constrain it to move in that way. As a reaction, the symmetry axis pushes the other two axes in the direction to slow down the torque free precession. Is it ok ?

The sequence starting at 5;19... just shows an impossible movement. A thin rod rotating in mid air, for example, cannot move in that way. If it does, it means that there is an applied force causing it, hence I called it "forced movement".

Thank you, glad you like it!

I see your point, but I didn't have this kind of problem, because in my chuck there is an empty space between the jaws and the bottom of the chuck, which was sufficient for the jaws to be reground in their full length, even using the shown ball diamond bit. If someone tried this method and had the problem you say, I agree that it is better to use a bit with a different shape, and not a ball, (or maybe even just a littler ball), until he can be sure to have the jaws reground in their full length.

It would spin much longer in vacuum conditions. Once I made a top to spin for four hours, in vacuum conditions: ruclips.net/video/Xah0ONSoq1k/видео.html

I never promoted my channel in any way.

Not sure to understand... what would be the rubber band for ?

@@iacoposimonelli7191 I was making light of the fact that you have a couple rubber bands securing your tachometers in the video. You machine such amazing things and I thought to myself "sometimes all you need is a rubber band".

@@mrtberto ah ah.. now I see... yes, sometimes easy solutions work well enough.

You can contact me at iacoposimonelli at yahoo.it, or on Instagram, (simonellispinningtops).

Thank you.. In this case I was especially concerned about performance, (perfect balance, tip sharpness, etc.), otherwise usually I give more attention to the aesthetics and the finishings of my tops.

Thanks. There is still room for improvemet, anyway, I think. Using a tungsten flywheel instead of a lead one, some other minutes could be gained. Now I don't consider anymore the 1 hour 30 minutes barrier for a finger top as an impossible goal. Difficult, yes, but not impossible.

​@@iacoposimonelli7191 Do you think that there is a way to optimize the manual spin up technique to achieve a higher rpm from the beginning?

@@alberthofmann420, I experimented in some different ways but at present I have the best results with the technique shown in the video. Another interesting technique seems that of this guy: ruclips.net/video/d9KCE-T54Kc/видео.html

If I made $80 a hour, I would buy more expensive tools which supposedly should not have problems like this.

Thank you, Dennis. The experience of making tops for 9 years makes itself felt, and I would say that this is a mature design, both aesthetically and functionally.

Thank you, Jorge! But my biggest pleasure is to make happy the future owners, so to let them go is acceptable for me.

Thank you! That part of the making was very labor intensive. I described the technique I used in the ITopSpin Forum.

Yes, almost exactly! For each one, of course.

Thank you for all your appreciation words!

You are welcome, glad it inspired you.

That's interesting, I too thought to similar solutions, like maybe two tops, one spinning on top of the other, to reduce the friction of the tip of the top above and make it spin a bit longer... but this is not the case of the top in the video, those solutions are not allowed by the rules in RecordSetter. There are not secrets or particular tricks for this longest spin, I explain everything in detail, in the description below the video and in the video linked there. Especially the recessed tip is quite helpful.

@iacoposimonelli7191 yeah I read the description the only mention of the base is it needs to be polished a lot. Thaks for your reply. I am thoroughly just interested. That top is so cool dude. While still cool in their own right. I kinda feel like all these tops with long duration times that contain one or multiple barrings are cheaters. I know the top in your video doesn't contain any. The fact neither does the base it is spinning on does not either makes this thing that much more of a work of art. So rad!

@@highinlife420, thank you. What are exactly the "barrings" ? Do you know tops that are made in that way ? Just for my curiosity.

@iacoposimonelli7191 yeah they have barring un the flywheel

Ciao Davide, io benino, non ci sono grosse novità. Tu, tutto bene ? Ti ringrazio delle calorose parole.. Sei una brava persona: umanamente sei sempre stato sensibile, come non molti. Sei anche un bravo musicista e compositore, (so quanto è difficile imparare a suonare perchè ho provato), lo fai con sentimento ed originalità. Sicchè l'affetto e la stima sono reciproci. Ti ricambio l'abbraccio. Iacopo

I made some tests and the best diameter of the knurl, for to reach the highest speed by multiple twirls, at least for my fingers, is 3-4 mm. The shaft below the knurl is only 1.5 mm, too thin.

@@iacoposimonelli7191 ever tried a knurled 2mm?

@@iacoposimonelli7191 I bet I could spin it. I've got the touch!

@@abundantharmony , I have a top with a 1.3 mm knurl and another one with a 1.8 mm knurl. They work well, but they are light tops. For a larger and heavier top a less narrow knurl works better.

Thank you. This one was an essential design, very much aimed for longest spins, and not very accurate in finishings.

Thank you, James. I believe that you have good room for improvement, with the tungsten. I am glad that you are doing research, you could find something and make your tops unique and original. You had various suggestions, in the comments of your latest videos. A good one, even if not very simple, was about an air cushion for the tip; I already experimented long time ago with a ball supported by an air cushion and I can confirm that the friction is really very low, I talked about it in the ITopSpin forum. I wanted to make a gyroscope with the air cushion, the movements would be more accurate, with the lower friction. A top with the air cushion could spin for a surprisingly long time, I suppose.

I think you are right, it would spin for some more than two hours, in the vacuum. If the top is specifically designed for to spin in vacuum conditions, it can spin even longer, like this one: ruclips.net/video/Xah0ONSoq1k/видео.html The optimal size for longest spins depends on some parameters, like the strength of the hand of the player, the density of the flywheel, the position of the tip, (external or recessed). Approximately, for my hands, and my kind of tops, with a brass flywheel, the optimal diameter is about 50-55 mm for tops to be started with a single twirl of the fingers, and about 70 mm for tops to be started by multiple twirls.

COG is center of gravity but NCOG I don't know what is it. Anyway; the position of the COG relatively to the tip influences the toppling speed. If the tip is very near to the COG, the top will topple at a very low speed, 48 RPM in the case of the top in the video. If this top could continue spinning without toppling until it doesn't spin anymore, it could spin for another 4 minutes, approximately, because this top loses about 12 RPM/minute in the last minutes of the spin.

@iacoposimonelli7191 ncog as in negative center of gravity, or a true maxwell top. I have always been curious if you would ever make one (I have asked you before on Insta haha)

@@konattaizumi, ah, ok... Yes, I made one, long time ago, the Nr. 12: ruclips.net/video/2htPfp2oMw8/видео.html The answer is, yes, it spins longer. If I made the top in the video with a NCOG, it would spin about 4 minutes longer.