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[ortwin]

Curtain-Ring-Top Nr.1 - PERIOD.
 

It has been my guess for a while that a platinum wheel with 3 needle spokes would have the absolute longest duration possible.

Now that was an inspiring remark for me! Especially the word "needle". I remembered these pins with the yellow glass head my wife has in her sewing set. When I looked for them I also found these white plastic rings - they are used for curtains or something.

It is not a well balanced top, still it is spinning for a bit more then a minute. If one considers the low density of the plastic and the quick and dirty execution in building the top ... . Probably even with a brass ring  10 minutes should be possible with a more careful setup.

[Jeremy McCreary]

@ortwin: Love your curtain-ring top! If you look beyond the high-performance category, a minute of spin time is quite good for a finger top. Nice demo of the value of the down-and-out mass distribution and designing with air resistance in mind.

I think you've set a fun but difficult challenge for yourself. I'd encourage you to keep an open mind about best solution for each spin-time benchmark. Engineering-wise, tops are way more complicated than they look, as many competing but coupled nonlinear processes are in play. And the sweet spots aren't always where you expect them.

Easier said than done with scratch-built tops, of course, but repeated guess-and-check cycles will serve you well.

Since my LEGO tops will never win spin-time contests against high-performance metal tops, I usually go for play value (including visual effects at speed) instead. Once a design is sufficiently entertaining, I then maximize its spin time as best I can.

Despite the wobble and spin time, your curtain-ring top's a lot of fun. Spin time isn't everything.

[ortwin]

Actually I just found something that could act as tip as well as a spoke:


Messeinsatz D.2mm Kugel L.35,7mm Gewinde M1,6 HM für Fühlhebelmessgerät 

Do not know what to call it in English. But you can get the ball (tip) in various hard materials that sound as if they were suited as a tip for a top. Also there are various ball diameters available. It is a part of an instrument used for example with e lathe to do precision measurements of contours. The shaft has a diameter of 2 mm in this case. So it is a lot more rigid then a pin of 0.6 mm diameter.

[the Earl of Whirl]

I think that curtain-ring top is clever and fun.  Good work!!!

[Iacopo]

Actually I just found something that could act as tip as well as a spoke:

You are ingenious !  I am sure you will make interesting things.

[ortwin]

Curtain-Ring Top  Nr. 2 - two spokes
   
This is the concept I suggested in my last post:

... two  [spokes] would be enough: thread a ball bead on your string, tension the string across the diameter of the flywheel, fix the ball bead on the string so that is sits right in the middle of the flywheel. ....

 



Actually this "curtain ring top" thing is becoming a little series of presentations of concept tops. Can anyone guess how many spokes my next curtain ring top will feature? And how many spokes the one after that?
I am happy with the stability of the spokes of this one. For the tip  I took a gold colored plastic pearl from the DIY jewelery kit of my  daughter. The hole is far too big. I still am happy enough with the outcome. I see the concept as having potential! Just chose the right materials and introduce the features I have in mind for better adjustment of the tip position, and there you go. Don't forget the setscrews though for static and dynamic balancing!
The reason I am making this series of concept tops is to find out what I will have somebody make for me on a lathe from proper top material. 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.

[ortwin]

Curtain-Ring-Top Nr. 0




Very quick build!


Not much of a top it seems. More like spinning a coin or Euler's disk. Actually this should have come first in this series, but at the time I presented the first Curtain-Ring-Top I did not know it would become a series. For completeness this spokeless top is necessary. Still it is not serious!

But actually I really want to incorporate it in the design of a metal stemless top. I mean I want to have a stemless top that I can use as Euler's disk when turned upside down. It seems the exact curvature of the rim is  crucial. Does somebody here  know what that curvature would be for a 4 cm diameter ring? It would not have to be the best Euler's disk ever, but spolling for 2 minutes while the top part could spin for 20 minutes would be nice. Also I want to approach this dual use thing from the other side: put my Euler disk (the original one) to a lathe and have a 2 mm hole drilled into the very center of its upper side, so it can be used as a stemless top after I put a ceramic ball (3 mm) to it.

[ortwin]

Curtain-Ring-Top Nr. 3




 This is the top  that most literally is like the one in the remark that inspired this whole "Curtain-Ring-Top" series:

 

It has been my guess for a while that a platinum wheel with 3 needle spokes would have the absolute longest duration possible.

 
Alright, it is not exactly a platinum wheel yet, but hey, I think you get the idea.
The fourth needle serves as tip as well as a stem. And the drop of glue that keeps the four yellow spheres together is not shown in the picture with the material.

The performance of this poorly made top is not that great. The very thin stem is hard to spin. It would be probably better to cut it off and just go stemless. Also I need you to excuse the video where the focus goes just somewhere. I admit that I was just too lazy to make a better video, but I promise to put more effort in the next tops of this series.
 

[Jeremy McCreary]

Clever prototype!

With such little ground clearance, not much room for wobble. But guessing this design would be very hard to center and balance, including keeping the spokes evenly spaced. Agree about the stem.

No need to apologize for the videos. It's fun to watch your experiments, and still way better than stills.

[ortwin]

Curtain-Ring-Top Nr. 4 - four spokes


 

Air drag is a bit higher than of Nr. 2 since it has more spokes, but it also has some advantages:

- the pebble or pearl or bead or what you might call it (plastic again from my daughters jewelry kit), does not need to be fixed to the center of the string, it stays there automatically

- adjustment of the pebble position (in one dimension) is possible by adjusting the relative tension of the two strings

The little pieces of wire visible in the first photo are shoved into the same holes as the strings  fastening them there. 

  



With a proper start with two hands it is spinning, without the ring touching the surface, for more than a minute.

[Jeremy McCreary]

Best one yet in terms of wobble! Decent spin time, too.

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.

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

[ortwin]

Curtain-Ring-Top Nr. 1.5 - colon top
This is the symmetric version of Nr. 1 :

 

It has some more air drag then Nr.1, but it has the advantage that tip positioning and top balancing can be performed independent of each other:

After the tip of the lower pin is adjusted by radial shifting and by tilting of the spoke so that is on the axis of the ring, the upper pin can radially shifted and tilted until the top is balanced.



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?

[ortwin]

Curtain-Ring-Top Nr. 6 - three double spokes, interchangeable tip




In principle the tip can be positioned precisely in the center by tensioning  the three double spokes accordingly. In this simple plastic version though it is not so easy once the top is completed.
 If the single lines are arranged properly next to each other, a double spoke can have the appearance of wide spoke which we said could possibly deliver an aerodynamic advantage. 
Even with only three (double) spokes, there are quite some different possibilities one  could arrange the strings/spokes: more complicated then the one shown here and also more simple possibilities.

The ceramic ball is glued to the inner small tube, the ball pen tip is just stuck into it. I have no idea if it has a steel ball or a tungsten carbide ball, but at this level  of refinement it will not matter at all. 


 The centering of the tip was only roughly done by eye judgement, no further balancing. Both versions Nr. 6a and 6b can spin for about a minute. Does that mean a brass version will spin for 10 minutes ? I could probably  spin it to the same starting RPM, that means almost ten times as much energy due to density difference. But then the loss of energy over time due to aerodynamics is roughly the same as in the plastic case, so ............I know this is not so easy, and also not completely correct, but 5 minutes should be possible with a brass Curtain_Ring_Top of similar (but  a bit more careful) build .
 As "spokes", thinner and stronger strings can be found in fishing supply stores.



0.03 mm sounds thin, the ones I used here measure 0.3 mm.There is even a fishing line called "Platinum". I am afraid it's only the name, otherwise we  would just take a reel of that stuff as flywheel....

This is the first of the Curtain-Ring-Tops that I am thinking of taking it up a step and build as a metal version. I really consider investing in a brass curtain ring! Well, maybe  after I make one or two other plastic Curtain-Ring-Tops. When I start with the brass ring tops, I will call it the "golden series". Just for the heck of it!;-)

[ta0]

Your ring tops look pretty good considering the materials you use.

Yeah, I think you can hit 5+ minutes with the brass ring if you build it carefully.

[Jeremy McCreary]

Curtain-Ring-Top Nr. 6 - three double spokes, interchangeable tip
Both versions Nr. 6a and 6b can spin for about a minute. Does that mean a brass version will spin for 10 minutes ? I could probably spin it to the same starting RPM, that means almost ten times as much energy due to density difference. But then the loss of energy over time due to aerodynamics is roughly the same as in the plastic case, so ............I know this is not so easy...

When I start with the brass ring tops, I will call it the "golden series". Just for the heck of it!;-)

Love this curtain-ring series -- especially the last one with the pen tip! My gut tells me that the spin time isn't going to end up proportional to ring density, but I'll think about it.