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: kzbin.info/www/bejne/jpLLYYKEiNSkZ80

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: kzbin.info/www/bejne/mmqudHhjiZpngcU

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: kzbin.info/www/bejne/jpLLYYKEiNSkZ80 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: kzbin.info/www/bejne/aJnXgZmmZ9SArZo 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.

Yes, true. Thanks.

Maybe it would spin for two or three hours... but I made one top, specifically for vacuum conditions, able to spin for four hours: kzbin.info/www/bejne/jpLLYYKEiNSkZ80

@@iacoposimonelli7191 wow I thought the levels of draglessness were so low already that it wouldn't make too much of a difference. super stuff! congrats

I think I have stronger hands than James.. but... 700 RPM higher ? So much higher ? I started the mine at 2750, and James is able to start his one at 2370, from the data he put on the ITopSpin forum: www.ta0.com/forum/index.php/topic,7137.msg78292.html#msg78292 But I don't have the data of his record spin. In any case, it isn't just a matter of stronger hands. I am the person who created this kind of tops, I made many experiments and I know them better than James, who simply copied what I did. But James used tungsten for the flywheel, which is a strong advantage over lead, the material I used for my flywheel. Anyway the making of James' top was not accurate, because you can see that his top wobbles most of the time, he had problems with the tip, and certainly he had an higher tip friction. Also his stem is not very good, for a competition top, and these things together make more difficult to even start the top at an highest speed. If you observe my tops you see that they don't wobble at all, unless at slow speed. I know how to make them. But I don't want to say too much, because then James will read and use the information for to improve "his" design. At least, he gave me credit, in the past, but recently his behaviour seems changed. James, among the many other details, knew from me the optimal diameter and weight he used for the mk22. But he doesn't say that, he is saying instead that "The geometry was determined using an equation I have been developing...", like wanting his followers to believe that this is totally his own work and merit, and in fact he received many compliments, even for the design, in his latest videos. You can understand that this has been a bit irritating for me. Also, it is the main reason that I decided to break his record.

@@iacoposimonelli7191 I meant no disrespect! I don't think the difference is strength of hands but stem design. The knurled stem with no handle or extension from James seems like it would be much more difficult to get to a higher RPM. I merely compared his vs your record videos, where he was only able to bring it to just under 2100 RPM.

@@caiomotta8910, I know you were not disrespectful, sorry if I made you think otherwise, it wasn't my intention. You are right about the stem, I can confirm that it is more difficult to spin hard a top with a short stem, the resultant starting speed is lower, I know it by experience. But I wasn't ironic saying that I have strong hands, I am very good at spinning, and that helps too.

@@iacoposimonelli7191I think you should just enjoy the competition and stop complaining about others stealing your ideas. It’s not a good look.

@@Tailspin80 , but I am not complaining about the others... I am almost proud that I started a trend, it means that there is some value in what I do. But the others generally just took inspiration from my work and then interpreted it in a personal way. Even James, who instaed is heavily using my ideas for years, I never complained about that, and I always have been kind with him. But when someone wants maliciously appropriate someone else's project for commercial purposes, talking about research and equations, when reality is that those ideas come from someone else, and not from his research and equations... I know it's not a good look... but it starts to be a bit irritating.

Thank you, Mikhail. My terminology is different from that you can find in books essentially because I didn't study physics and I don't know that kind of terminology well. In the video I use the term "nutation" in the physical sense, (torque free wobble), and not in the kinematical sense, (secondary wobble disturbing the main one). I use the term "nutation" for to tell the "torque free precession" too, (for to make evident that the two movements are the same). I have some good intuition for physics, I found the reason that nutation happens in that way, and I really wanted to share it because at my knowledge there aren't any other intuitive explanations about it. I don't use vectors because I find them confusing, I prefer to use the arrows pointing directly in the real direction of the forces and movements, it is more intuitive and it makes the reasoning faster and easier.

It doesn't work very well to put a very hot flywheel on a wooden core, the wood might shrink and crack. It is better to use epoxy and joints in this case.