Subject:
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RE: Call me a Lego pureist if you will but...
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 25 Apr 2001 23:40:27 GMT
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Original-From:
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Tilman Sporkert <tilman@webmethods.com(NoMoreSpam)>
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Viewed:
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457 times
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...
> I toyed with sewing thread. I tied it to the end of the dart and fed it
> through the cannon.
> Here are my observations. • ...
> 3. Paying out thread without severely slowing down the dart is the hard
> part. My attempts failed. You need some kind of spindle to rewind the
> thread, but I believe you would have to remove it in order to let the
> thread pay out unfettered.
If you don't pre-accelerate the winch or outright power it, then some of the
energy that propels the dart out of the cannon will be needed to accelerate
the spindel. That will happen right away, as the dart leaves the cannon.
Beyond that, it just has to keep the spindle turning, to keep up with the
speed of the slowing dart.
> Gear up a old 9V motor to spin the spindle very fast, and then spin it • just
> before and while the dart is flying. You may be able to keep up the • thread
> payout with enough gearing.
Or use a larger diameter spindle instead of gearing it up. The trick of
course is to careful time everything so that the dart always has some slack
in the thread, and at the same time not unreel the thread too fast to get it
tangled up. If you don't want to reel the dart in at the same insane speed,
you could build a set of gears that engage an additional reduction gear when
turning the other direction.
> Why not use a winch with only 1 circlular plate on the axle? Once the
> projectile is re-loaded turn the winch through 90 degree's so that the • axle
> is in line with the dart. Fire the dart and the thread will spool off the
> end of the axle automatically, you will of course have to be careful how • you
> wind the thread onto the axle in the first place so it doesn't get
tangled.
I believe this will twist the thread. If you have ever struggled with a
garden hose, you'll know what that can do.
Tilman
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Message has 2 Replies:
Message is in Reply To:
 | | Re: Call me a Lego pureist if you will but...
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| I toyed with sewing thread. I tied it to the end of the dart and fed it through the cannon. Here are my observations. 1. Rewinding and reloading works fairly well. As long as the dart doesn't approach the cannon at a right angle to the barrel, it (...) (23 years ago, 25-Apr-01, to lugnet.robotics)
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