Ideas for Junkyard Wars

I spent the last two days (only possible on sabbatical time!) reading all the suggestions for topics for the Junkyard Wars TV show on their discussion site, about 4000 of them. Here for your amusement are the comments and suggestions I posted:

Suit of Armour

Subject: Re: suit of armor
Topic: Junkyard Challenge Suggestions
Author: agmsmith
Date: 02/22/01 20:33:01

Say, that's a good idea. The educational aspect of armour making is reasonably large: it has a long history (wasn't the screwdriver invented by an armourer?), there are quite a few techniques (padding vs sheer inertial weight, joints and fastenings) worth looking at and explaining.

Also armour making isn't a dead science - look at reactive tank armour, the Bear research suit (the maker would be a good expert or judge), space micro-meteor armour, motorcycle helmets, and the Society for Creative Anachronism (SCA) which recreates medieval battles (another good source of experts).

Music Box

Subject: Re: Giant Music Box Mechanism
Topic: Junkyard Challenge Suggestions
Author: agmsmith
Date: 02/23/01 15:39:24

goofybob said "Ever take apart a music box? Neat, huh?"

I can see it now. Yellow team makes a slowly spinning oil drum with chunks of iron welded on the side providing the pattern of notes. Trip hammers are lifted by the iron chunks as the drum turns and drop on various things - from xylophone metal bars to cymbals and drums, piano strings and maybe even breakable glass objects (replaced after each note).

Orange team makes a disk with bumps to encode the music. Electrical contacts touch the bumps and trigger the notes, playing car horns, buzzers and bells, and maybe even wind instruments made from old computer fans and pipes.

Other instruments, like the flame tubes suggested earlier could also be hooked up. If they can find things which make the right noises, they could make the already mentioned "TALKING MACHINE!". An educational side note would explain the tuning of the instruments, such as adding weight to the car horn diaphrams or adjusting pipe lengths in a pipe organ.

One big factor in making a music machine is the timing accuracy. One team could try making a centrifugal governor on their drum rotating motor. The other could use a pendulum and a ratchet mechanism for advancing their drum.

Other alternatives to the drum/disk are a roll of paper with holes (like those used by old player pianos) or a "page" of sheet metal (sheet music? :-) with holes/bumps. The drum is easy to make - bend a piece of steel rod into a circle the same size as the drum, cut it up into pieces corresponding in length to the common note lengths, then weld them to the barrel (chalk off timing marks all the way around the drum before you start to avoid incremental timing errors). Possibly pre-make the drum and choose tunes which don't have too many different notes.

A Jukebox version capable of playing multiple tunes would be an additional challenge. Either do it by physically switching barrels (under push-button control would be nice, but I expect manual heaving around of oil drums to be more practical), or have multi-track barrels and shift the barrel sideways to play the second tune.

Besides physical force and electrical activation, pneumatic (a whistling machine!), water or steam mechanisms could also be tried.

The competition would be for playing ability (number of correct notes), timing accuracy, and sheer durability (which one lasts longest). Also have a group of listeners decide which one sounds best and award extra points for that.

A final challenge would be to play a duet or multi-instrument piece between the teams (each gets a drum with their half of the song) or against an audio CD (mechanical karaoke!).

Body Flight

Subject: Re: Wind tunnel
Topic: Junkyard Challenge Suggestions
Author: agmsmith
Date: 02/23/01 15:59:57

Speaking of wind tunnels, a vertical wind tunnel would be interesting. Make a powerful fan run by a V8 engine at the bottom, have a safety grid above the fan, and above that the tunnel. OK, so now you've got wind blowing upwards. Not that spectacular, until someone jumps down the tube and starts flying! It's called "Body Flight" and there's a nice FAQ about it at

The competition could be for heaviest person/object flown, or for duration, or for acrobatics.


Subject: Re: Elevator
Topic: Junkyard Challenge Suggestions
Author: agmsmith
Date: 02/23/01 17:27:25

An elevator / lift is a good idea. It is even better if you add automatic controls to it - a pushbutton at each level to summon the elevator. One team could use electrical relays (taken from cars) to put together their controller. There are well known (though obsolete) techniques for designing such relay "ladders".

The other team could make a state machine, much like a music box, but with elevator actions encoded rather than musical notes. Pushing the button would advance it one notch, which would have a mark in the motor control position to turn on the lift motor in the upwards direction, making the elevator go up. When it reached the top floor, the state machine gets advanced to the next position, which has no motor mark (the elevator stops) and has a mark which re-enables the pushbutton for going down (pushing the button while the elevator is moving should do nothing). To avoid the complexity of branching states, it would be limited to 2 floors.

Other more mechanical lever and gear mechanisms could be made to do the same job, possibly more simply than a music box style controller.

Compacting Earth

Subject: Re: Steam Roller
Topic: Junkyard Challenge Suggestions
Author: agmsmith
Date: 02/23/01 17:41:51

A so-so challenge (easy in other words) would be to pack as much gravel into a hole as possible. This is done in real life while making foundations for houses or flattening gravel for roadbeds.

The Steam Roller (or alternate powered roller) is one technique. Another one is to thump the earth with a heavy weight. I've seen gas powered hopping machines doing this during road construction, and I've heard of much larger thumping machines. The difficulty is in making such a machine durable since it would tend to shake itself apart.

Refrigeration of Gases

Topic: Junkyard Challenge Suggestions
Author: agmsmith
Date: 02/23/01 17:49:38

Long ago, I read about a similar project in Scientific American for making a multi-stage refrigerator out of ordinary parts for converting gases into liquids. Liquid nitrogen should be doable, as well as carbon dioxide (though it turns solid I believe). I wonder if you could use solid CO2 for making carbonated soft drinks? At least, you'd be able to make some nice dry ice fog effects.

Vacuum Tube

Topic: Junkyard Challenge Suggestions
Author: agmsmith
Date: 02/23/01 18:03:01

Besides making just a light, they could make a vacuum tube (valve) for amplifying electrical signals. That could then be used as part of a radio. Well, make it simpler, and just have it as an audio amplifier driving some old car speakers from a microphone.

As a pretext, the host's loudhailer/bullhorn is broken and he/she needs a replacement. Loudest one wins. Test by shouting a message over increasing distances.

Pinball Machine

Topic: Junkyard Challenge Suggestions
Author: agmsmith
Date: 02/23/01 21:16:27

Your pinball machine is a fun idea. Oddly enough, nobody else has mentioned it, though a couple of people did come close with enhancements for the scrapyard clock.

I prefer a more complex design than what you suggested. Things like electrically or pneumatically driven ball kickers. A score counter made from a car odometer (though a larger counter would be better). Sound effects. Maybe make it with an oversize ball.

The final competition could be a game tournament. Or if the games are designed with open edges at the high end, they could be placed end to end to make a two team game.

Good Ideas in Last 4000 Messages

Subject: Some Good Ideas Found In The Last 4000 Messages
Topic: Junkyard Challenge Suggestions
Author: agmsmith
Date: 02/23/01 21:30:28

After reading the last 4000 or so messages, I have noted a few of the more interesting messages (besides mine :-). Here are a few of them, search for the subject in quotes to find them:

"A BUNCH Of Suggestions" has a good summary of many of the common ideas (Zamboni, Drilling Rig) and a few cool but impossible ones (Radar Set, Pulse Jet), that still make interesting reading and may even be possible if you give the scrappers a week instead of 10 hours.

"Can crusher, windmill, a C-130-dropped..." is another good collection of ideas, with most of them on the practical side.

"a few JYW suggestions" has most of the doable standard ideas (forklift, log splitter) with good explainations. Well, except for the recurring Battlebots, tank and helicopter ideas.

"Duel Wheel vehicle" is the most innovative vehicle - a two wheel thing capable of moving the whole team. The trick is that the two wheels are side by side and the team is slung under the axle. Good description.

"Remote Controlled Submersible" gives enough details to make the project actually seem possible.

- Alex

Copyright © 2001 by Alexander G. M. Smith.