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ITSA General Assembly: December 5th - 12th

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 71 
 on: August 18, 2019, 07:47:24 PM 
Started by butterfingers - Last post by butterfingers
I like behind the back Trapeze. Thanks for sharing.
Thank you, Cecil. I struggled with that one for a while. I have to remind myself that the target area is the body of the top and not the tip.

I enjoyed the video with your grandson - that was post hip surgery for you, right?

 72 
 on: August 18, 2019, 07:43:11 PM 
Started by butterfingers - Last post by butterfingers
- Submitted for consideration: potential new tricks from a trapeze throw launched upward landing on the open palm. The attached video shows several successful throws and catches. The 'Widowmaker' is a throw which is pulled back to the hand and caught with the fingers facing backward. The effect is best if caught above the shoulder close to the ear. I show the catch from both profiles. I think the trick looks best if the catch is hidden by the head and the player turns to reveal the top spinning in the hand. The 'Skydiver' is the same throw but no pull back. The top is caught in the palm with the fingers facing forward. It comes into the hand like a boomerang with a tall arc but has less speed. It's a good throw if the player intends to go straight into a regeneration move as there is less spin when the top lands in the hand. I have practiced a bit with this and it's possible to release the top with a pretty impressive amount of height.
- I have not seen anyone do this before and I was inspired by a prior post about regenerations where the person who shared their video was disappointed that their tricks were all done at a low height and lacked vertical interest. I thought the video was good but it led me to start thinking about ways to raise things up a bit like these throws. I am trying to work out how to do consistent throws from regenerations like diabolo players but I need to work at it a bit more before I share.
- No music on the video this time around....and diet and exercise started 2 weeks ago. Hopefully there will be less of me in future videos.

YouTube link here:

https://youtu.be/D4zOPGEhei0

 73 
 on: August 18, 2019, 07:36:47 PM 
Started by andydecleyre - Last post by Jeremy McCreary
Interesting bowl.  We have been using IKEA bowls for a number of these activities.

Dug this fine vintage Melmac bowl out of some old camping gear boxes in the garage. Gotta be at least 30 years old.

What do your IKEA bowls look like, and how do you use them?

 74 
 on: August 18, 2019, 07:23:21 PM 
Started by andydecleyre - Last post by the Earl of Whirl
Interesting bowl.  We have been using IKEA bowls for a number of these activities.

 75 
 on: August 18, 2019, 06:50:21 PM 
Started by andydecleyre - Last post by Jeremy McCreary
Behold my gyrocyclotron -- a gyroscopically stabilized high-energy rolling top accelerator. Here you see my only workable bowl and one of my best LEGO gyrocyclotron tops...



Before answering your questions, wondering if the top's orbiting motion about the bowl's vertical centerline is really a gyroscopic precession in the usual sense? The top's nearly constant small inward tilt while orbiting is surely maintained gyroscopically. But the orbiting itself seems more like just rolling tip travel around a banked circular track.

So to be safe, I'm sticking with "orbiting" for now.

So, with the bowl you are achieving counter-precession regenerations.... Can you achieve at all forward regens in a bowl?

Exclusively, and really doubt it, resp. But if anyone could pull off high-speed forward regens in a bowl, it would be you.

If the top is to orbit the bowl by rolling without scraping at high speed, I think the rolling contact pretty much has to be outboard of the spin axis. And that means an orbital direction opposite spin. In my hands, trying to make the top orbit the other way instantly kills its spin, and it goes down with a thud.

But are [regenerations in the bowl] easier than the forward-precession regenerations on a flat plate?

Much easier, and I am to skill toys as canaries are to mines: The smallest challenges trip me up. :o

The only tricky part is sustaining max orbital speed -- and hence max spin rate. This occurs just before the tip climbs over the rim, and that's best avoided by listening closely to the whining sound made by the tip on the bowl.

Is there an ideal shallow bowl in which forward and counter regens are equally easy?

You're right in thinking that the bowl can't be too deep for its diameter. But too shallow is just as problematic. I'm having a hard time imagining a bowl that would make forward regens possible while containing the top well enough to achieve the high orbital speeds I'm getting.

This circular serving bowl works beautifully. The other 9 I found around the house didn't work at all. For starters, most had inner bottom flats. The initial transition from spinning top to spinning+orbiting top is almost spontaneous when the bowl's inner bottom is curved but fails with even a small flat.



The inner surface closely approximates part of a sphere of radius R = 126 mm, and its depth is only 54% of that. The aperture is 224 mm across. The slope at the inside rim is ~25° from vertical, and any workable top must have a scrape angle a good bit smaller than that. That means a rotor packing a lot of AMI into a relatively small maximum radius with a lot of clearance underneath. Hence the wide but thin high-density rubber tire and long black tip holder to its right.

You need a ball tip with some grip, and the larger the top's AMI, the larger its maximum radius of curvature must be. This small hard rubber tire makes a perfect tip for the high-AMI top shown. The tread lets you gauge orbital speed by ear, and that helps you bring the tip right up to the rim without going over.



 76 
 on: August 18, 2019, 06:00:14 PM 
Started by ta0 - Last post by cecil
Contest. To me this is the best performance with a small top I’ve ever seen. You see hard hitting tricks - not over done with regenerations. I don’t like more than three regenerations of one kind.
https://youtu.be/KijNZAK9pvI

 77 
 on: August 18, 2019, 05:39:44 PM 
Started by Renee - Last post by robtsou
Wow!  57 dollars?!?!

I know! It would cost me more in gas than flying!

 78 
 on: August 18, 2019, 05:37:43 PM 
Started by Trip - Last post by robtsou
Nice meeting you at World's Trip!  Welcome to our little community!

 79 
 on: August 18, 2019, 05:34:14 PM 
Started by ta0 - Last post by robtsou
Well, just to check in, I had a great time seeing everyone and hanging out at World's again this year!  I'm pretty sure I did more top stuff than yoyo stuff!  I wish I could make it to Miamisburg but the timing is too close (maybe I can plan better for next year).

Rob

 80 
 on: August 18, 2019, 05:26:17 PM 
Started by Renee - Last post by the Earl of Whirl
Wow!  57 dollars?!?!

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