Subject:
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Re: Hammer Help
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 13 Dec 2002 18:48:51 GMT
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Viewed:
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2135 times
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In the prototype I used string and winch to set the hammer. I've decided
not to use it on the robot - string can too easily get caught and entangled
in stuff, especially if it goes up agianst another robot.
On the prototype it works surprisingly well, even though I used a small
winch. When it is released the sting/winch is not that resistive, the gears
that are attached to the winch are connected to a differential that spins
freely. The elastics pulling the hammer down easily overcomes any friction.
I never even thought of using a larger winch - I used the lego winch (and
elastic) that came in the Bungee Chopper (2854). Using a larger winch would
have increased the speed in which the hammer could have been raised.
Last night I had a brake through. I initally dismissed using pneumatics to
do this, although they are very powerful they are fairly slow, I was wrong.
I tried using a single large cylinder attached close to the rotation point
of the hammer and was very impressed with the result, it came down fast and
hard - as long as the pressure is high. I'm now messing around with
positioning of the cylinder to achieve the best result and will probibly add
a second cylinder. Of course now I have to make a motor driven pneumatic
switch and a pressure-regulated compressor - but thanks to other people
there are lots of designs on how to do this.
In lugnet.robotics, PeterBalch <PeterBalch@compuserve.com> writes:
> Roy =
>
>
> I thought about designing such a thing a while ago.
>
> My decision was that I'd make something like a Roman ballista. I'd wind u=
> p
> a string on a winch to cock the hammer then unwind the string all the way=
>
> back again. The catch would be released by another mechanism attached to
> the winding motor when the the winding motor was fully unwound. My idea w=
> as
> that the string would be so loose that it wouldn't offer any resistance -=
>
> unlike a gear mechanism.
>
> I also thought about a much simpler idea:
>
> Imagine the lid of, say, a peanut butter jar. The lid slowly turns and th=
> e
> string wraps around around it - one full turn cocks the hammer. As the
> complete turn comes around, a "tooth" on the rim of the peanut butter jar=
>
> lid nudges the string sideways so it falls off the edge of the lid and is=
>
> free to unwind suddenly. Maybe a cutaway part would work better than a
> tooth. As for Lego, well, the inner drum-shaped cores of the big chunky
> tyres should work and the "tooth" could be a piece of axle held at 45
> degrees to the rim.
>
>
> However, note the "thought about" - any robot stuff that isn't actually
> built DOESN'T COUNT.
>
> Good luck
>
> Peter
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Message is in Reply To:
 | | Hammer Help
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| Roy I thought about designing such a thing a while ago. My decision was that I'd make something like a Roman ballista. I'd wind up a string on a winch to cock the hammer then unwind the string all the way back again. The catch would be released by (...) (24 years ago, 13-Dec-02, to lugnet.robotics)
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