Curtain Ring tops + follow ups

[Jeremy McCreary]

I'm all for the play-around approach. No predicting spin time -- even for the simple geometry you're planning. Just wanted to raise a design issue I run into all the time...

At parity of air and tip resistances and top geometry other than CM height, you're often left with a tricky trade-off between scrape angle and the release speed you can attain without scraping.

Often, spin time is best served by upping the scrape angle so you can really crank on the top -- despite the resulting increase in critical speed. Where's the sweet spot? Test, test, test!

[ortwin]

....No predicting spin time -- even for the simple geometry you're planning. ...

No prediction of spin time is fine, I can understand. But starting speed should be easy. Also a simple plot of critical speed versus ground clearance of this specific flywheel. ( So if I think it is so easy and simple why do I not do it myself? Just because I am such a sloth or because I fear I will fail? No easy answer to this one.)

[Jeremy McCreary]

Clearly time for the tough love approach. You're on your own now, my friend. Looking forward to that plot! It'll be easy with the equations I've given you.

Now off to make a video having nothing to do with tops.

MfG, Jeremy

[ortwin]

Now off to make a video having nothing to do with tops.

I know that doing something like that is possible! But is it worth it?

[Jeremy McCreary]

Have to admit, pretty scary.

But we must do the scary things to lead a rich and full life. Unless they kill you first.

[ortwin]

Pick a number!
Since I still don't have those specially made screws to connect the nylon string spokes to the flywheel for the top I am actually planning, I am just screwing around a bit with that (big) flywheel:


Tau and Pi tops.
Mercedes top
Waggon wheel top

Just shows the versatility of that "found" flywheel. Better centering of the tip static and dynamic balancing would still be possible and also badly needed for good performance but for now I did not do any of that. Maybe once the suspension top with this flywheel is up I'll do it for comparing the performance of the different spokes.

[ta0]

Tau and Pi tops.

They look great. You made good use of the flywheel.

[Jeremy McCreary]

Excellent! Basic flywheel dimensions? Which version spins longest so far, given current state of balance?

[ortwin]

Curtain-Ring-Top Nr. 12 - ....
....
(outer diameter: 90 mm, inner diameter: 68 mm, height 12 mm, weight: about 85 g )
...

In the meantime I centered/balanced a bit a further version. This version has three spokes. Starting speed 420 RPM gave a spin time of 8:35 toppling at around 100 RPM.
https://youtu.be/eJovDKG9wu8

[Jeremy McCreary]

Almost 9 minutes! Nicely centered, too. Bravo!

The flywheel's aluminum and the screws are steel, correct?

[ortwin]

....
The flywheel's aluminum and the screws are steel, correct?

Affirmative! And the steel ball (1/2 inch) tip comes from a GEOMAG set.

And yet another one: The PEACE TOP


Edit: Oh, this last one was a bit of misunderstanding: one of my inner voices screamed: "Please stop!" (meaning "stop making silly tops"). But my conscious self misunderstood it for "Peace Top". And this is what came from that......
But wait, how about a STOP TOP? Stop signs around here are octagonal, would not work with this flywheels threads....

https://www.google.com/search?q=stop+si ... client=img

[Jeremy McCreary]

In my experience, given how far gone you are already, if you have the parts to make more iterations of this top, you will.

Resistance is futile.

[ta0]

Edit: Oh, this last one was a bit of misunderstanding: one of my inner voices screamed: "Please stop!" (meaning "stop making silly tops"). But my conscious self misunderstood it for "Peace Top". And this is what came from that......

But wait, how about a STOP TOP? Stop signs around here are octagonal, would not work with this flywheels threads....

Sure. It would only have half the sides of Jeremy's hexadecagonal top.

[Jeremy McCreary]

Used this 8-sided flywheel in my original batch of suspension tops...



Spins for ~60 s.

[ortwin]

In my experience, given how far gone you are already, if you have the parts to make more iterations of this top, you will.

Resistance is futile.

But it seems you are better off: in the LEGO world the number of possibilities is denumerable, otherwise possibilities are innumerable.