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Subject: 
Re: Ping-Pong Ball Shooter
Newsgroups: 
lugnet.robotics
Date: 
Thu, 13 Jan 2000 07:56:18 GMT
Original-From: 
Julian Sharpe <jsharpe@xtra.co#stopspam#.nz>
Viewed: 
645 times
  
Just the other day a friend and I had a go at building a lego shooter. The
aim was to fire 2x2 bricks. After a couple of designs, the most successful
turned out to be a slot shooter. It consisted of a shoot with slipper tiles
on the bottom. At one end of the shoot, we mounted an air filled medium
sized dune buggy type tyre geared up 3:1 to the old (fast) type lego motor.

You simply feed the bricks up the shoot, and when they reached the tyre, the
tyre would grip them and accelerate the bricks out the end.

With this shooter you could fire maybe 20-30 feet.

I am sure that a similar design for ping-pong balls could be designed with a
little thought...

----- Original Message -----
From: "The WordMeister" <dwilcox@wordsmithdigital.com>
To: "Lego Robotics List" <lego-robotics@crynwr.com>
Sent: Thursday, 13 January 2000 9:21 am
Subject: Ping-Pong Ball Shooter


Okay, I promise not to mention my rack-and-pinion steering model in this
post ... [Rats, I've blown it already.]

Our current family robotics project is to develop a robot that will shoot
ping-pong balls, as well as hunt them down and reload 'em (that part I can
handle).

Last night I constructed a couple of prototype mechanisms. The one which
seems to be the most effective uses two of the smaller angle beams which are
mounted on a 40t gear which rotates at a fairly high speed. The ping-pong
ball is rolled down a track  made of four 16x1  Technic beams (each "rail")
having two beams mounted end-to-end. When the ball comes into contact with
the spinning assembly, it gets sent back up the rail, and will (most of the
time) get launched 3 or 4 feet forward. I've added a flywheel (the biggest
wheel that comes with the RIS) as well, although that isn't vital.

I also worked on a crude catapult-like assembly, but the rotating shooter
seems to work better, and presents fewer design problems.

What other mechanisms have been tried or could be tried? Just looking for
some additional design inspiration and ideas. I'd like to try a
pinball-plunger-type mechanism, but haven't figured out a good way to build
it and motorize it yet.

I'm pretty well set for pieces as well, having the RIS and the Code Pilot,
plus 1 extra motor, plus lots more Technic pieces. So I have two
differentials, two clutch gears, and four motors--if any of that helps.

--Doug Wilcox

WordSmith Digital Document Services
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