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[Jeremy McCreary]

Top 4. The original "Hercules in Chains" presented above. Note how chains attach to flywheel and core.


Ease of use = Poor
Ground clearance ~ 3 mm
Scrape angle ~ 2.1 1.1°
Tip resistance = High
Best spin time = 72 s
Play value = Poor
Comments = Insecure grip, poor torque transmission, way too easy to scrape


Relative to Top 4, revised Tops 4b and 4c had...
1. New inboard chain attachments more coaxial with the transverse core
2. New blue flywheel plugs
3. In Top 4b only, outboard chain attachments above the flywheel
4. In Top 4c only, smaller-diameter core with hard plastic contact

Change 1 improved twirling grip by making the chains more horizontal. Change 2 increased flywheel mass and AMI, probably with reduced TMI/AMI ratio. All that was good for critical speed, but who knows the net effect on flywheel air resistance? What's worse — a bumpier flywheel, or leaving its small peripheral holes wide open, as in Top 4?

And why that stupid core tire in Tops 4 and 4b? Simple: They needed it to have any ground clearance at all. The small space for the core between chains left no other viable LEGO solution.

Top 4b. Same ground clearance as Top 4.


Ease of use = Poor but better than Top 4
Ground clearance ~ 3 mm
Scrape angle ~ 2.1 1.1°
Tip resistance = High
Best spin time ~ 45 s (gold tire)
Play value = Poor but better than Top 4

Top 4c. Increased ground clearance, much lower tip resistance.


Ease of use = Fair
Ground clearance ~ 5 mm
Scrape angle ~ 3.5 1.8°
Tip resistance = Low
Best spin time ~ 85 s
Play value = Pretty good

Conclusions
Top 4c was the keeper here, as it had the best ease of use, play value, and spin time: Top 4 = 72 s, Top 4b = 45 s, Top 4c = 85 s. In fact, Top 4c was close to Top 5 on these fronts.

Air resistance varied little in this series, but tip resistance, mass properties, and release speed varied significantly. The big drop in spin time from Top 4 to 4b suggests that even a little more weight on the tire's rubber contact made tip resistance a lot worse.

Why did Top 4c spin so much longer than 4b despite a higher critical speed? Much lower tip resistance + significantly higher release speed — the latter due to a less challenging scrape angle. How? With more wiggle room, I could apply more starting torque without scraping or spreading the inboard chain attachments apart.

[ortwin]

If anybody should be interested in some acronyms in use in Germany:
https://youtu.be/uUV3KvnvT-w 

"(acronym desensitization treatments)"
I was under the impression that desensitization treatments start slow, not like the brutal first free treatment of Jeremy or the video above. I would have thought starting with one acronym per thousand words would be the safe way to go. After all we don't want to lose ta0 to a lunatic asylum!

[ortwin]

Now, I know that ta0 thinks that tau, defined as τ ≡ 2 π, is more fundamental than π, as it's the circle's circumference/radius ratio (CRR) rather than CDR. And as someone who much prefers dealing in radii rather than diameters, I wholeheartedly agree.

...

Should a PI Day Top not look more like Curtain-Ring top Nr. 1 ? But probably that is too hard to be done with LEGO. 

[Jeremy McCreary]

@ortwin: That video was pure acronymophiliac heaven! Found this explanation of all those luscious German abbreviations.

The black radius of my TPT (tau promotion top) disappears in motion. Close enough for me, and no way to balance what you have in mind in LEGO (Danish abbreviation for "play well").

Tried the soft ADT approach in the 1st  post here, in which only one acronym (ST) was used among way too many full words. Great restraint on my part, I might add.

So I consulted the ATM (advanced therapeutics manual) of the AAS (American Acronymophobia Society) as to what to do about a defiant patient response. And the ATM advised going straight to AAT (acronym assault therapy). Which I did, again to a defiant response.

According to the ADM (advanced diagnostic manual) of the AAS, that indicates a case of HRA (hopelessly refractory acronymophobia). So nothing left to do now but to provide emotional support around exposures.

Sorry ta0, that must've been just awful.

And with that, I'm going to FDH my breakfast and then FDH the other half.

MfG, Jeremy

[ta0]

Thanks for the link Jeremy. I'm not impressed. If I was German, even I would be in favor of acronyms. I have no problem with using ARD to abbreviate Arbeitsgemeinschaft der Öffentlich-Rechtlichen Rundfunkanstalten Deutschlands.  German should have more acronyms!

Should a PI Day Top not look more like Curtain-Ring top Nr. 1 ? But probably that is too hard to be done with LEGO. 

You are right. An hexadecagon is close to a circle, but distinct enough to have it's own Wikipedia page: https://en.wikipedia.org/wiki/Hexadecagon

What I like the most about the top is its name, Hercules in Chains 

[Jeremy McCreary]

If I was German, even I would be in favor of acronyms....

 

author=ta0 link=topic=6432.msg69852#msg69852 date=1616426415]An hexadecagon is close to a circle, but distinct enough to have it's own Wikipedia page: https://en.wikipedia.org/wiki/Hexadecagon

Thanks for the link. Nice discussion of the symmetries.

Alas, smooth surfaces of revolution are hard to come by in LEGO, and the few parts avaliable often don't lend themselves well to topmaking. I need to talk to them about that. They should know better in Denmark!

The hexadecagonal hoop is as close as you can get to a smooth circular toroid of that size.

What I like the most about the top is its name, Hercules in Chains 

ortwin deserves most of the credit there. He came up with the visual of the core trying to escape captivity. And that triggered long-repressed memories of a really bad beefcake movie I saw at age 9.

Mom might have liked it, though.

[Jeremy McCreary]

Should a PI Day Top not look more like Curtain-Ring top Nr. 1 ?

Just looked again. Having presented only a radius, and not a diameter, that's definitely a Tau Day top.

[Jeremy McCreary]

New axial suspension top

With bling! Really loving this "dark azure" blue LEGO introduced 2-3 years ago.



PING to burn and negligible wobble, as line tension and core centering are both finely adjustable by twisting the outboard chain attachments as shown.



Adding the dark gray (eventually black) tiles to the bottom of the flywheel upped spin time from 26 to 34 s.



Ease of use = Good
Ground clearance ~ 8 mm
Scrape angle ~ 3.2°
Best spin time = 34 s
Play value = Good

[ortwin]

PING to burn and negligible wobble, as line tension and core centering are both finely adjustable by twisting the outboard chain attachments as shown

Getting closer!
I don't fully understand the adjustment. Do those chain attachments not just twist back if left alone?
I can't imagine that you would use c.... g... .

[Jeremy McCreary]

Getting closer!
I don't fully understand the adjustment. Do those chain attachments not just twist back if left alone?
I can't imagine that you would use c.... g... .

Nope, the outboard chain attachments stay put without (gulp) glue.

But I did use a trick to encourage that, and it involved cutting short segments of 3.2 mm rod from some black antennas.You can see them inside the chains' hollow gold outboard studs.

[ortwin]

 
Inspired by Jeremy's tops in this thread, I found I had build this beginners LEGO suspension top when finished playing today with my little son and his LEGO box.
(I guess you have to click the last picture to see the animated gif)

[Jeremy McCreary]

Excellent use of that white helmet!

I also tried to make 4 lines from 2 long chains when I ran out of short chains. But I never came up with a core as good as that helmet. And I have lots of helmets. Well done!

[ortwin]

Today I thought about what the most simple suspension top would be. 
Something with a flexible flywheel? Maybe a lasso can be transformed into  a spinning top?   
Can the "clown top" be reduced to on only the collar stem and tip? 
Or maybe something like a bola with a lightweight central ball acting as the tip?


Probably there are some tops already, made from LEGO or otherwise, that are very simple suspension tops and you just need to post some links.
But in the meantime I try to make something.

[Jeremy McCreary]

Today I thought about what the most simple suspension top would be.

With the definition I use, hard to see how you could get a suspension top much simpler than "Son of Hercules in Chains" here...



Remember, the lines can only have strength in tension. And of course, it has to work like a true top with a non-zero critical speed.

Would also be nice if it were reasonably well-balanced and could handle speeds well above critcal.

[ortwin]

...

With the definition I use, hard to see how you could get a suspension top much simpler than "Son of Hercules in Chains" here...

I guess I did not really mean simpler, I meant a top the flywheel of which is flexible and goes more or less by the same rules as your tension lines, give or take a few weights. That is how I got the picture of the lasso,  maybe the video of the clown top brought me to that.
Does any of this make sense?