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Author Topic: introducing myself  (Read 10914 times)

Jeremy McCreary

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Re: introducing myself
« Reply #45 on: February 11, 2021, 05:51:44 PM »

Another Curtain Ring Top - two spokes
Actually this "curtain ring top" thing is becoming a little series of presentations of concept tops.... I hope you don't mind too much that I do not put much time and effort in the presentation and videos. I think the concepts can be understood from these and that is what I want to share at this point.

Please keep the concept videos comin' -- quality's fine!

When you get to 4 flywheel suspension cables...

https://youtu.be/3zMySTrJ0-w

The main AMI reservoir here is an octagonal disk rather than a flywheel, it's suspended from chains instead of smooth cables, and the aerodynamics are pretty lousy.

But nothing inherently wrong with flexible "spokes". In fact, they open up some interesting design possibilities.

You just have to worry about wobble due solely to structural oscillations excited during spin-up -- even if the dynamic balance is perfect at rest. Wobbles can cut into spin time.
« Last Edit: February 12, 2021, 01:51:35 AM by Jeremy McCreary »
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Art is how we decorate space, music is how we decorate time ... and with spinning tops, we decorate both.
—after Jean-Michel Basquiat, 1960-1988

Everything in the world is strange and marvelous to well-open eyes.
—Jose Ortega y Gasset, 1883-1955

ortwin

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Re: introducing myself
« Reply #46 on: February 12, 2021, 03:50:36 PM »

@jeremy: great looking top in chains!
When I first watched the video, I thought the the octagon was going up and down  a few times du[size=78%]ring the same spin. Okay this is not the case, but is there some type of top that also shows some deterministic chaos in some nice clearly visible way? Probably you just have to send a link to a video of one your Lego tops.[/size]
I just thought the humble pendulum, being one the guinea pig of physics, has some pretty nice chaotic cousins. What about the top or the gyroscope, another guinea pig of physics? Do you know of any  versions that display chaotic behaviour?



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In the broader world of tops, nothing's everything!  —  Jeremy McCreary

Jeremy McCreary

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Re: introducing myself
« Reply #47 on: February 12, 2021, 05:34:41 PM »

@jeremy: great looking top in chains!
When I first watched the video, I thought the the octagon was going up and down  a few times du[size=78%]ring the same spin. Okay this is not the case, but is there some type of top that also shows some deterministic chaos in some nice clearly visible way? Probably you just have to send a link to a video of one your Lego tops.[/size]
I just thought the humble pendulum, being one the guinea pig of physics, has some pretty nice chaotic cousins. What about the top or the gyroscope, another guinea pig of physics? Do you know of any  versions that display chaotic behaviour?

I think it's common for tops to show seemingly erratic transient behaviors that appear to be very sensitive to initial conditions -- i.e., to fine, unknowable details of the release, or after being poked.

But these early antics tend to decay into steadier behaviors like sleep or precession +/- nutation, so perhaps not formally chaotic. Also not sure about the erratic behavior sometimes seen during the final death spiral.

But I do have some oddly behaving tops to show you. Video coming. Maybe some cases of dissipation-induced instability.



Wait, here's something akin to a gyroscopic inverted compound pendulum...

https://youtu.be/S9zQgu8hqdA

Love that phrase "guinea pig of physics". Tops definitely belong to that club.
« Last Edit: February 12, 2021, 07:49:30 PM by Jeremy McCreary »
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ortwin

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Re: introducing myself
« Reply #48 on: February 18, 2021, 02:14:38 PM »

...
I have a number of self-centering tops with various moving or loose or floppy parts onboard. Still trying to understand exactly how it works.

We might have some misunderstanding going on here, not sure though. In these tops there is no loose or moving part or something like that when it is finished  and ready to be spun. The string is tensioned , like on a guitar. Well maybe not with not quite that much pull, but it is pretty stiff now. The self centering of the bead happens when tension is put on to the two strings. 
Tensegrity might be one big name for the concept.
But then again you might have understood everything just alright and I am misunderstanding your remark.




 Is the video age-restricted to keep your daughter from finding out you're taking her stuff?




My daughter is alright with that, she knows about it. I don't know exactly why YouTube put a age restriction on this video. I can't remove it, I filed  a complaint. My guess is that some AI software at YouTube is analyzing all videos and that it misinterpreted something here.
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Jeremy McCreary

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Re: introducing myself
« Reply #49 on: February 23, 2021, 11:25:24 PM »

Curtain-Ring-Top Nr. 1.5 - colon top
Besides the commercially available "exclamation mark top"and the PERIOD top (curtain rin top nr. 1) this "colon top" is the third punctuation top I know of, can you think of any other ones?

I like the colon top. Here's the asterisk top...


« Last Edit: February 23, 2021, 11:27:56 PM by Jeremy McCreary »
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ortwin

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Re: introducing myself
« Reply #50 on: March 03, 2021, 03:23:39 AM »

Just for the record !
*
Remember this  single-lp-adapter ? A downsized version of it, for example made by 3D-printing, could also turn a wedding band reversibly  into a spinning top. The sphere acting as a the tip would be glued into the central hole.  Even some balancing is possible by moving tiny weights along the (three) spokes. Would this lead to a new world record in spinning time?
Or go the other way: take one of these original adapters off the record and construct a flywheel that fits to it. Into the central hole you can stick something like a short piece of a ball pen that works as stem and as the tip of the top at the same time.

Just for the record: everybody is invited to put these ideas to the test by actually building these type of tops. I will never claim that my ideas were used without my consent.

* the look of some of these adapters remind be of the profile pic of "Aerobie". Before I joined this forum and just browsed around here, Aerobie often showed up when I searched for subjects that are of interest to me. It seemed especially Aerobie could have similar goals here as I do. But now I see he was not active in the last 2 1/2 years. Any body knows what happened? Did he lose interest in the topic? Maybe he just reached all the goals in the field. I checked a bit more and found out that Alan Adler really was the inventor of that special boomerang! Well, some 30 years ago I had one of those and enjoyed playing with it.  Probably ended up hanging in some tree. That is the biggest draw back in constructing a boomerang that way: it likes to get picked up by branches.

« Last Edit: March 03, 2021, 04:40:45 AM by ortwin »
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Jeremy McCreary

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Re: introducing myself
« Reply #51 on: March 03, 2021, 10:23:46 AM »

Love your ideas for making tops out of household and hardware store items. Please keep it up, even if the spin times aren't world-class.

Personally, I've found good play value in tops that stay up only 10 seconds. Just depends on what else the top brings to the table, and clever construction definitely works for me.

No idea what happened to Aerobie, but he made some great finger tops. His string-pull starts based on a hollow stem should be in widespread use. Sent him a PM a year or so ago but no response.
« Last Edit: March 03, 2021, 10:28:54 AM by Jeremy McCreary »
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ortwin

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Re: introducing myself
« Reply #52 on: March 07, 2021, 08:44:34 AM »

Love your ideas for making tops out of household and hardware store items. ...
Yesterday I found this nice quick build on YouTube that beats me by far!
https://youtu.be/mU4uKVTJPyY
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ortwin

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Re: introducing myself
« Reply #53 on: March 07, 2021, 09:04:36 AM »

Are members banned from the forum if fidget spinners are visible in their posts?
Well, I will soon find out. No risk no fun!  Maybe I get away with it since this is still my introductory thread. ;)
Over in the Curtain-Ring top thread, I presented a simple wind up starter.

Curtain-Ring-Top Nr. 8 - 4 spokes, tungsten carbide tip, wind up starter included
This is an improved version, but it has no Curtain-Ring, so it ends up here.



It was a lot easier to build than with the curtain ring. Many improvements would still be possible here: CM could be brought lower, some balancing could be done, the tip could use a pencil sharpener...........

https://youtu.be/fr_Tn2PZRIw
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Jeremy McCreary

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Re: introducing myself
« Reply #54 on: March 07, 2021, 12:36:09 PM »

Are members banned from the forum if fidget spinners are visible in their posts?

The only way to avoid a session with Mistress von Karman -- and trust me, you don't want that -- is to convert the fidget into a cool top first. And you certainly did that here.

Best invention yet! Keep 'em coming, my friend!
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ta0

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Re: introducing myself
« Reply #55 on: March 07, 2021, 01:57:23 PM »

The fidget top with the elastic starter is a wonderful design!  8) Well done!

My youngest son once sold tops made with CD's and marbles at school: Market Day at my son's school. Unfortunately, I didn't keep any for my collection  :'(
« Last Edit: March 07, 2021, 01:59:28 PM by ta0 »
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ortwin

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Re: introducing myself
« Reply #56 on: March 07, 2021, 02:49:13 PM »

Thank you Jeremy and ta0 for your kind words! I also love these little things that come up on the way to the actual goal: long spin time!I am aware that the way and the things along the way can be better then then end goal itself, even when it should be reached.
On the way to long spin times I plan to make use of this set that arrived yesterday:




Two chuck adapters (€ 8,-) from Amazon.They should become the central parts in one of  my next spinning tops with high experimental/play value.I need to drill some holes in the chuck so the thin fishing line spokes (that green line arrived also already) can attach. The tip can easily be exchanged (different material, different diameters, different shapes) and can be varied in height. I will start with 1 mm tungsten carbide balls in ball pen mines. Even a stem can be attached and fixed by screws if needed.
So this is my concept for the next experimental stage. I know which setscrews I want in the flywheel and so on. One of the biggest question remaining is the flywheel contour which we discuss in the other thread. Once that is settled for me, I can tell my friend with the lathe what I want him to to carve out of some brass.

« Last Edit: March 07, 2021, 02:51:44 PM by ortwin »
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Jeremy McCreary

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Re: introducing myself
« Reply #57 on: March 08, 2021, 02:30:49 PM »

You're going totally modular on us ortwin! Love it!
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ortwin

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Re: introducing myself
« Reply #58 on: March 08, 2021, 03:18:39 PM »

You're going totally modular on us ortwin! Love it!
Well I figure once we found out the playful way what works better and maybe what works best, we can still think about how to put it together in a nice way without the chuck.
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