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[zaggernut]

But if the goal were to compete with others' tops on spin time, I'd disqualify that tip. Ditto for a tip designed to develop a flat after release.

And for a world-record spin time, I'd want to examine the tip afterward for a flat that might have prolonged spin time artificially.

But then anyone aiming for a WR in this category will need to own a microscope to prove the lack of a flat spot right after finishing a record spin, plus it is much easier to prove the existence of a visible flatspot than its absence, given the size of the ball under magnification. Not to mention the question of if it is even possible for a totally fresh corundum/carbide ball tip to develop absolutely no observeable flat spot after an hour long spin. That leaves us with only spike-tipped tops as possible contenders, which (according to Iacopo's pictures) tend to drill spherical craters into even carbide bases, and unlike flatspots provide no additional righting force to the top. Allowing only spike tips is probably the easiest way to circumvent the flatspot issue, but it also disqualifies basically every commercial high-performance EDC top out there.

- must follow form of current world record holder

I was confused about this point, what exactly does this mean?

[ortwin]

...That leaves us with only spike-tipped tops as possible contenders, which (according to Iacopo's pictures) tend to drill spherical craters into even carbide bases, and unlike flatspots provide no additional righting force to the top. Allowing only spike tips is probably the easiest way to circumvent the flatspot issue, ...

Not sure that even spike tips would circumvent the issue: I can imagine a spike tip digging a hole in which the top can sit without tipping over. Well, at least in theory, I do not know if that was ever observed.

[Jeremy McCreary]

Well it "might" give a faster release speed, but maybe not. The optimum stem diameter for maximum release speed, depends, as you know, strongly on the AMI of the top. For a top with a given AMI a smaller stem diameter corresponds to a "higher gear", which might not be optimal for highest release speed. Imagine you put the chain on your bicycle to a certain gearwheel and you want to determine how fast you can be after the first initial half step starting the bicycle. If the gearwheel (connected to the wheel) is very small,  you hardly move the bike. If the gearwheel is  very large it is easy to move at first but the speed after half a "step" will also be small because there is so small a length where the force is acting. What is optimal depends also on your strength, or rather your weight in the bicycle example.
So for a given flywheel/AMI and person to operate the top, it would be best to have a modular system where you can test all stem diameters from 3 mm to say 15 mm in steps of 1 mm.
We had similar discussions before, like this one , there are a few posts before and after the actual link also.

Generally agree. And I do have a modular stem system that's given me extensive experience with stems 3.2, 4.8, and 6.4 mm in diameter.

Let's set theory aside and approach this empirically. For the 52-minute Plier W Mg top, we're given mass M = 75 g. The maker seems to like rotors on the order of 1.5 inches = 38 mm in max diameter, so I'll assume a max radius R ~ 19 mm. Taking proportions from the video, I get a stem OD of ~11 mm.

I estimate the Plier's axial radius of gyration K to be within the tungsten ring nearer its inner edge — say, at K ~ 16 mm. Then the AMI is M K² ~  2e-5 kg m² = 0.71 MR². Which seems about right for a rotor between a disk and a ring in shape.

I have many tops with AMIs larger and smaller than this, and for most of them, a splined LEGO axle with an OD of 4.8 mm gives the highest release speeds AND the best tilt control. Based on that experience and the estimated AMI above, pretty sure that a 4.8 mm stem would serve the Plier top well. But the existing stem is over twice that thick.

Further evidence that an 11 mm OD stem is too thick for this top: You've seen one of my higher-inertia tops — the von Braun space station. Its AMI of ~8.4e-5 kg m² is ~4 times larger than that of the Plier top. And it's too much for a 4.8 mm stem alone.

So I use a stepped stem with the fingers starting at 6.4 mm and spiraling upward to finish the twirl at 4.8 mm. Quite effective, but even the 6.4 mm part is significantly thinner than the Plier stem.

Finally, recall that 4 mm is Iacopo's go-to stem OD.

Of course, as you point out, testing a range of stem ODs would be the best way to find the one that maximizes spin time for a given top and user. Easier said than done with a precision metal top turned on a lathe, but the Plier guy seems to have the requisite skills and materials.

[Jeremy McCreary]

But then anyone aiming for a WR in this category will need to own a microscope to prove the lack of a flat spot right after finishing a record spin, plus it is much easier to prove the existence of a visible flatspot than its absence, given the size of the ball under magnification. Not to mention the question of if it is even possible for a totally fresh corundum/carbide ball tip to develop absolutely no observeable flat spot after an hour long spin. That leaves us with only spike-tipped tops as possible contenders, which (according to Iacopo's pictures) tend to drill spherical craters into even carbide bases, and unlike flatspots provide no additional righting force to the top. Allowing only spike tips is probably the easiest way to circumvent the flatspot issue, but it also disqualifies basically every commercial high-performance EDC top out there.

This whole spin-time record business turns out be pretty thorny, doesn't it? An inexpensive 14x loupe would suffice for inspection purposes.

[ta0]

Your experimental results showing that the stem of the Plier top is too wide are quite convincing, Jeremy.

For the world record, perhaps one could experimentally determine the critical speed of the top by spinning it at low speed several times (so it spins for about a minute) and measuring the spin when it tumbles (a mark on the top and a camera is all that's needed). Then the record would the shorter of the time to fall or the time to get to the critical spin.

[Iacopo]

- must follow form of current world record holder

I was confused about this point, what exactly does this mean?

I don't know, it seems a bit vague in fact..

[ortwin]

...
For the world record, perhaps one could experimentally determine the critical speed of the top by spinning it at low speed several times (so it spins for about a minute) and measuring the spin when it tumbles (a mark on the top and a camera is all that's needed). Then the record would the shorter of the time to fall or the time to get to the critical spin.

Since this sounds a bit like a mix of some suggestions I made earlier in this topic, I think I should support these ideas. Not completely clean and simple, but a step in the right direction I would say. I would also say that we should not care too much about the Guinness rules or the Record Setter rules. In this forum there is for sure more than twice as much expertise on spinning tops than in the Guiness and Record Setter organisations combined. ITSA rules rule!

[Jeremy McCreary]

In this forum there is for sure more than twice as much expertise on spinning tops than in the Guiness and Record Setter organisations combined. ITSA rules rule!

Agree, we should develop reasonable rules and try to get them adopted more broadly.

So, clearly, and concisely, exactly what ITSA rules for spin time records would you propose?

[ortwin]

....
So, clearly, and concisely, exactly what ITSA rules for spin time records would you propose?

If it would be that easy to state clearly and concisely those rules, I would have done so three years ago.
Anyways, I think we need to account for at least two different types of tops:
recessed tip and multiple twirl being one of them,
external tip, no pedestal, single twirl by fingers of one hand, another one.


 

[Jeremy McCreary]

If it would be that easy to state clearly and concisely those rules, I would have done so three years ago.
Anyways, I think we need to account for at least two different types of tops:
recessed tip and multiple twirl being one of them,
external tip, no pedestal, single twirl by fingers of one hands, another one.

Not that I'll ever be competing with non-LEGO tops on spin time, but I'm not alone in having non-pedestal tops that can be twirled more than once during spin-up. And pedestals could be advantageous with external tips.

So maybe a 6-fold classification:
1. Recessed tip? R = yes, r = no.
2. Pedestal used? P = yes, p = no.
3. Single twirl? S = yes, s = no.

A classic Simonelli could compete in Classes RPS and RPs, but historically in the latter. Classes RpS and Rps would necessarily be vacant.

Any practical reason to separate finger and palm starts?

The ITSA Board could appoint a Spin Time Commission of experienced endurance top makers and users to sort it all out and propose rules to the Board for final approval.

[zaggernut]

I would also say that we should not care too much about the Guinness rules or the Record Setter rules. In this forum there is for sure more than twice as much expertise on spinning tops than in the Guiness and Record Setter organisations combined. ITSA rules rule!

Agree. Video game speedruns are self-moderated, in that the rules are made by the community of speedrunners for that specific game, and record attempts are moderated by chosen people from the community. The website they use is great for this purpose, with community-driven moderation and support for adding subcategories like recessed tip, pedestal etc. They even have IRL categories like a pencil sharpening record, but this is but an offshoot of an existing game with a similar premise. The website's rules state they don't allow non video game activies.

We could make a category on this forum for record attempts along with a leaderboard, just like most speedrunning communties did in the past. The hard part would be getting others to join, but that should not be much of an issue given the #1 and #2 attempts at the very least are from here. Also, I had never heard of RecordSetter before entering the spinning top rabbit hole, so not exactly stiff competition we're going up against.

[ortwin]

...
Not that I'll ever be competing with non-LEGO tops on spin time, ...

Your input here is nevertheless valuable and much needed!

...
So maybe a 6-fold classification:
..Classes RPS and RPs, ...

There goes simple and clear ...
No, I get it of course, but seen from the outside a 6-fold classification is not "sexy" at all. I think we can have 6-fold classification, but at most two of those classes should be made to stand out somehow, to set the picture one has in mind when thinking of endurance tops. The picture I am thinking of, is a Simonelli top and one of those Plier tops. (But actually I visually prefer the Li Fan Timesniper and the Kemner Dynamo over the Plier tops.)

...
Any practical reason to separate finger and palm starts?

It was Iacopo that mentioned at one point that with palm starts you have the potential to put a lot more energy in the top as with fingers - that is most probably true. And the reasoning is,  that it would be unfair to put them in the same league. But up to now I have not seen a palm start spin longer than 10 minutes I think (edit: hm, a post by myself reports that I reached something close to 20 minutes). So for now it would be fine to not separate finger and palm starts. Once palm starts take a clear lead one could rethink this.

...
The ITSA Board could appoint a Spin Time Commission of experienced endurance top makers and users to sort it all out and propose rules to the Board for final approval.

The "Spin Time Commission" should meet in person in Hawaii to discuss things. All expenses paid by ITSA.
I'm in! Who else?

[Iacopo]

It was Iacopo that mentioned at one point that with palm starts you have the potential to put a lot more energy in the top as with fingers - that is most probably true. And the reasoning is,  that it would be unfair to put them in the same league. But up to now I have not seen a plam start spin longer than 10 minutes I think. So for now it would be fine to not separate finger and palm starts. Once palm starts take a clear lead one could rethink this.

The fact that up to now nobody seems to have made a palm top for longest spins isn't a reason for to mix the categories, I think.

The amount of energy that can be put in the top is of paramount importance when longest spins are wanted.
I would propose a division in main categories based on the way the top is started:
finger tops, palm tops, throw tops, tops started with motors...
Then each category could be divided in subcategories.

[Jeremy McCreary]

@ortwin, that Li Fan top is definitely a looker, but it didn't fall in 2 different runs on the spintopenthusiast site.

[zaggernut]

I am wondering if there could be reasons other than a flat spot for a top to come to a standing stop. Take a look at this top that comes to a standing stop:


Now I have my doubts as to the video publisher not seeing any flatspots with his '60x hand lens', that sounds more like microscope territory to me. But it is also a sub 1 gram top with a tiny ruby ball tip, so I imagine any flat spot would be too tiny to be worth noting. Could the standing stop be some esoteric molecular contact force? Or is it more likely to simply be a particularly lucky deviation within manufacturing tolerance of the sphericity of the ball? I don't buy his argument for the balancing of the top being just too good, as at this mass, even his finger oils on the stem should throw off factory balancing by enough.