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Author Topic: Rigidity in tops  (Read 1626 times)

Jeremy McCreary

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Rigidity in tops
« on: December 16, 2016, 04:37:08 PM »

I spend a lot of time worrying about rigidity in LEGO tops, as lack thereof never seems to bode well for either can often be a problem for spin time or smoothness or both.

Is rigidity ever of practical concern in throwing tops, perhaps in other ways? Non-LEGO finger tops?
« Last Edit: March 22, 2020, 08:29:51 PM by Jeremy McCreary »
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Playing with the physical world through LEGO

Diz

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Re: Rigidity in tops
« Reply #1 on: December 17, 2016, 03:35:08 AM »

I have a string thrown top made of soft rubber which is difficult to spin. In fact when I try a boomerang throw the string seems to squeeze the top midair and refuses to return to hand!
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ta0

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Re: Rigidity in tops
« Reply #2 on: December 17, 2016, 12:03:35 PM »

I have a string thrown top made of soft rubber which is difficult to spin. In fact when I try a boomerang throw the string seems to squeeze the top midair and refuses to return to hand!
Is that a commercial top or one you made? I have been wondering for a long time if a bouncy rubber top would work.  :-\
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Diz

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Re: Rigidity in tops
« Reply #3 on: December 17, 2016, 01:36:57 PM »

Ta0 it's a commercial top, similar in proportion to a Duncan Ripcord but slightly smaller. I'll send it to you if you'd like it for your collection. It was likely produced to be safe around furniture and floors. And yes it will bounce off things!
J
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ta0

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Re: Rigidity in tops
« Reply #4 on: December 17, 2016, 03:09:00 PM »

Ta0 it's a commercial top, similar in proportion to a Duncan Ripcord but slightly smaller. I'll send it to you if you'd like it for your collection. It was likely produced to be safe around furniture and floors. And yes it will bounce off things!
J
Thanks!  :) I sure would like to have an unusual top that is not in my collection. But perhaps it has a wiggle spiral going around the body and a large plastic cone tip (and it is solid)?  In that case I do have it.

I was thinking of a hollow top of a rubbery material like the shell of a diabolo. That one I suspect could have problems.
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Diz

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Re: Rigidity in tops
« Reply #5 on: December 17, 2016, 03:33:07 PM »

Aaah then you do have it already! :D
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ta0

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Re: Rigidity in tops
« Reply #6 on: December 17, 2016, 06:28:19 PM »

You made me play with it (I don't recall when was the last time I did). Even spinning it on the floor was not trivial (it is easier to snap start). Getting a boomerang took me tens of tries  :-[ I finally nailed a couple. The longest probably spun like 7 seconds on my hand.

The reason the top did not come back to your hand is that the "neck" of the tip is very thick. Because the string is pulling further away from the axle, your pull tends to rotate the top, not pull it backwards. This is always a problem with tops that have this characteristic. The solution is to not give it much momentum forward and to pull hard. By the way, I used the thick string of a koma and that helps (just a few wraps, no higher then the second revolution of the spiral).



The drawing instructions on how to spin it don't seem very helpful. It would seem that you have to twist the wrist and pull back after the top is released from the string!  :P  >:D

Something that I first found surprising was that when spinning I could see black circles around the top. The wiggle marking is a spiral and you wouldn't expect that. On close inspection (at least on mine) the spiral is not uniform but one one side it is almost horizontal.
« Last Edit: December 18, 2016, 06:24:08 PM by ta0 »
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Jeremy McCreary

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Re: Rigidity in tops
« Reply #7 on: December 18, 2016, 03:49:26 AM »

How about this for a hollow rubber top: Put some kind of tip on a hard rubber classic Kong toy for dogs and give it a throw?

Possibly adding to the difficulty of boomeranging the rubber top you already have is the spin-up power lost to sinkage of the string into the rubber just behind the separation point when string tension is high.
« Last Edit: December 18, 2016, 11:21:25 AM by Jeremy McCreary »
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Jeremy McCreary

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Re: Rigidity in tops
« Reply #8 on: March 22, 2020, 06:13:13 PM »

How about this for a hollow rubber top: Put some kind of tip on a hard rubber classic Kong toy for dogs and give it a throw?

Thanks to jim, finally made my own
"Kong top" with improvised LEGO stem and tip
...



Can't be started on the ground by hand but sleeps 90 s without wobble with a suitable starter.

Bet it could be a decent throwing top in the right hands and with the right tip -- as long as you don't touch the rubber in play.
« Last Edit: March 22, 2020, 08:29:07 PM by Jeremy McCreary »
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