Subject:
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Re: Need Balls!
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Newsgroups:
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lugnet.robotics
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Date:
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Thu, 21 Oct 1999 21:38:57 GMT
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Viewed:
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622 times
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In lugnet.robotics, Ben Erwin <berwin@tufts.edu> writes:
> J G Gregory wrote:
>
> > I am coaching a team in the FLL contest. I need a supply of those 5 or 6
> > nub diameter foam balls -- at least 30. Does anyone have an idea of a
> > source? Is there any similar thing that comes from Nerf?
> >
> > How many balls come with the RoboSports expansion set?
> >
> > Any advice appreciated.
> >
> > --Jack Gregory
>
> Oh man... I'm coaching a team too. I didn't realize that we were going to
> have to find our own balls! :)
>
> -Ben
Finding your own balls isn't really as difficult as it sounds -- you just
have to know where to look. Most Toys backward R Us stores have a large
Nerf selection with a variety of sizes and shapes. They're usually larger
than the balls that come with MINDSTORMS, but if you can't find the exact
size you need, you can cut your own balls with a sharp scissors. But you'll
have to make very careful snips, otherwise they won't roll around smoothly.
Once you get the basic shape, then you can also sandpaper your balls to make
them perfectly round. When you're ready to test, mark each ball with a
black dot, then roll them across the floor to check for rotational biases.
Subsequent removal of the marks is sometimes difficult, however, often
requiring vigorous rubbing or additional sandpapering, so an alternative
marking technique is to straightly insert a pin into each ball and check the
rotational balance that way. Note that the pin neither changes the shape of
your ball nor leaves any marks behind when removed. However, you'll have to
find pins whose length approximately equals the diameter of your balls, so
that the center of gravity remain at the proper location. Finally, once
you've got ball properly rounded and balanced, it's a pretty good bet that
your robots will be able to knock them around and pick them up with very
little trouble (provided that your robots are properly programmed, of
course). Hope this helps.
--Todd
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Message has 1 Reply:
 | | Re: Need Balls!
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| HI, I was just wondering what this FLL thing was that you guys were talking about? Thanks in advance. Nicolas Gauthier (25 years ago, 21-Oct-99, to lugnet.robotics)
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Message is in Reply To:
| | Re: Need Balls!
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| Oh man... I'm coaching a team too. I didn't realize that we were going to have to find our own balls! :) -Ben (...) (25 years ago, 21-Oct-99, to lugnet.robotics)
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