Bill Gurstelle is your MAKEcation counselor for the make-a-trebuchet Family Challenge. Build a trebuchet and post pictures tagged "MAKEcation" in the MAKE Flickr pool to enter to win a $100 Maker Shed gift certificate!

Has anyone else noticed a lot of movies with trebuchets and other catapults in them? I sure have. For instance, they were the special-effects stars in the Lord of the Rings trilogy, particularly, the Return of the King. They've been on TV as well: Fox Sports, the Simpsons, Northern Exposure, PBS Nova, Warner Brother's cartoons and probably many others.

I built a fairly large and historically accurate trebuchet a couple of years ago. I named it Ludgar, the Warwolf, after the huge trebuchet built by Edward I of England in 1304. Ludgar was really big, accounts say that Edward cut down an entire forest to obtain enough wood.

• Chronicles of Narnia
• Night at the Museum
• Kingdom of Heaven
• Alexander
• King Arthur
• LOTR Return of the King
• Gladiator
• Monty Python and the Holy Grail (I especially like the part of this movie where John Cleese says "Fetchez la vaca" in a cheesy French accent.)
• Robin Hood Prince of Thieves
• Robin and Marian
• Robin Hood Men in Tights
• The Scorpion King
• Flesh and Blood (the Rose)
• Jabberwocky
• Army of Darkness
• Timeline
• Young Einstein
• Willow
• Star Wars #6
• Richie Rich
• The Messenger
• Excalibur
• Joan of Arc
• Troy
• El Cid

Timeline was a so so movie but the trebuchet is wonderful. Kingdom of Heaven and Gladiator have excellent battle sequences with catapults. The LOTR movies have well done CGI trebuchets.

More:

• MAKEcations: deadline extended!
• How to build a catapult part 1
• How to build a catapult part 2: triggers and releases
• Maker Workshop - Portable Trebuchet on Make: television
  
• MAKEcation trebuchet bundle in the Maker Shed
  

Bill Gurstelle is your MAKEcation counselor for the make-a-trebuchet Family Challenge. Build a trebuchet and post pictures tagged "MAKEcation" in the MAKE Flickr pool to enter to win a $100 Maker Shed gift certificate!

More in my series of posts on How to Build a Catapult. In this post, I discuss Catapults, Ballistas, Trebuchets and the Triggers, Releases, and Latches that operate them.

I receive quite a few inquiries about making catapults and trebuchets. And among the most frequent questions is: how do I build the trigger? It's an important question.

Catapults are fun and educational to build and operate. When building a catapult, trebuchet, ballista, mangonel, or any of the hundred names by which such hurling machines are known, you'll find out that the mechanism that releases the throwing arm is often the most complicated part of the machine.

You may build your own release, which is tricky because you need to design the latch so that it will release reliably under full load. Actually, you can get pretty creative about triggers.

But considering how cheap and easy it is to buy one, it might make more sense to use one of the commercial solutions below, and spend your time working on the other aspects of the machine.I've spent time researching the best triggers and releases for small catapults. There are three good, off-the-shelf solutions: The archer's arrow release, the sailor's pelican hook, and the horse trainer's panic snap.

Archer's Arrow Release:

This is the premier solution. Works dependably, quickly and very smoothly. It costs a bit more, but of all the catapult releases I've tried, I like this one the best. Find it at a sporting goods store with an archery department, or find it online.

Sailor's Pelican Hook:

This is another excellent hurling machine trigger. Its normal use is in sailing, where it is used to securely hold and release lines and ropes. Basically a pelican hook is a hinged hook that can be quickly secured or released by a sliding ring. It is quite a bit less expensive than an arrow release, but it holds securely under load. The downside is that they can be awkward to release sometimes. Find it at a boating store or online.

Horse Trainer's Panic Snap:

A panic snap is a mechanism often used between a lead and a horse's harness. They are decent catapult triggers because they can be disconnected under load. A panic snap is specially built so that the latching mechanism is separate from the load bearing structure. Just pull back on the latch and the load releases. Very inexpensive, but not as smooth or dependable as the arrow release. Find it at a tack shop or online.

More:

• MAKEcations: deadline extended!
• Maker Workshop - Portable Trebuchet on Make: television
  
• MAKEcation trebuchet bundle in the Maker Shed
  

Bill Gurstelle is your MAKEcation counselor for the make-a-trebuchet Family Challenge. Build a trebuchet and post pictures tagged "MAKEcation" in the MAKE Flickr pool to enter to win a $100 Maker Shed gift certificate!

Catapults are wonderful, exciting examples of technology. (I use the catapult to mean any projectile hurling device of ancient descent. Such devices may use springs, counterweights, or human energy.) They are simple yet complex; delicate yet brutal. Unlike looking at say your computer or an airliner, you can pretty much look at a trebuchet or ballista and kind of understand what's going on. On the other hand, the physics and kinematics are complex and intricate.

Tips for building a catapults:

• Purity of concept aside, it pays to use modern materials. While it might be cool to build a coiled rope torsion spring like the ancient Greeks, you'll probably find it difficult to get enough spring power without torquing down the ropes so much that you'll crush the frame., Experiment with the use of bungee cords if you build a torsion or tension spring powered model.
• I find hardwoods and metal frames work better than softwoods. Practically speaking though, dimensional lumber is what most people wind up using. Overbuild if you can, doubling up the wooden frame pieces. You'll be glad you did.
• If you're making a gravity powered trebuchet, consider forgoing the pouch on the sling and simply attach a cord to the object you're hurling:. That way, when the projectile flies, then so does the cord. I call that "a sacrificial sling." It's way, way easier.
• Consider your release mechanism carefully. For bigger catapults, consider a pelican hook (it's a peice of hardware that sailors use, and you get them at stores that cater to boating) or possible an archer's arrow release. You get those at sporting goods stores. Their fairly cheap and they work well with smaller machines. Much more info on catapult triggers in a forthcoming post.

There's a lot of historical information and plans for many sorts of catapults in my book, The Art of the Catapult which is on sale at the Maker Shed.

More:

• MAKEcations: deadline extended!
• Maker Workshop - Portable Trebuchet on Make: television
  
• MAKEcation trebuchet bundle in the Maker Shed
  

MAKE commenter whitehead made this neat project that he calls a patio cooler. He turned an ordinary plastic cooler into a nice piece of patio furniture by building a frame for it out of cypress wood and spare sheet metal roofing. It even comes complete with a vintage bottle opener!

Have you started your cooler hacking project yet? Remember to add your photos, tagged "MAKEcation," to the MAKE Flickr pool to enter to win a $100 Maker Shed gift certificate! If you need a little extra time, you are in luck, as the deadline has been extended to Wednesday, Sept. 9.

Back to school is fast approaching, so it's time to get in one more family project before the summer's over. We've extended the MAKEcation challenge deadline to September 9, two days after you're done enjoying your Labor Day weekend. We have $100 gift certificates to the Maker Shed just waiting for you to come and grab them when your family (we use the term loosely) learns to solder, hacks a cooler, or builds a backyard trebuchet. All you have to do is add photos of your project to the MAKE Flickr pool tagged "MAKEcation" to enter! If you get stuck, have questions, or just want to chat, email campcounselor@makezine.com. What are you waiting for?

Top prize in each category: $100 Maker Shed Gift Certificate

Runners up: The Best of MAKE or The Best of Instructables

Teach your family to solder:

• Super learn-to-solder roundup
  
• MAKEcation learn to solder bundle in the Maker Shed
• Toolbox: Soldering essentials, part 1
  
• Toolbox, Soldering tools, part 2
  
• Let the MAKEcation solder-fest BEGIN!
  

Cooler hacking challenge:

• Brainstorming cooler hacking ideas
  
• Hack your cooler: Mobilize it!
• Hack your cooler: Other cooler hacks
• MAKEcation Cooler Hacking Challenge
  

Family trebuchet challenge:

• Maker Workshop - Portable Trebuchet on Make: television
• MAKEcation trebuchet bundle in the Maker Shed
  
• Altoids tin trebuchet
  
• Make a Trebuchet - Make: Video Podcast
  
• Make a Trebuchet - Make: PDF Podcast
  
• The MAKEcation Family Trebuchet Challenge!  

Mountain Bike Rescue

This Friday, May 22nd, is the deadline for the MakeShift challenge that appeared in MAKE, Volume 17. To enter, send a detailed description of your MakeShift solution with sketches and/or photos to makeshift@makezine.com.
Here's the challenge:

The Scenario: You and your best friend, both experienced mountain bikers, take off on a daylong jaunt to explore a little-known and rocky canyon trail. The ride is challenging but spectacular until, as you finally decide to turn around and head back, your friend's bike hits a loose rock, skids out from under him, and they both topple off the edge of the trail down into the canyon. Smashing his knee in the fall, your friend manages to land on a thin, unstable ledge about 15 feet straight down from the trail, only able to keep himself from falling farther by grabbing onto a small but secure tree branch jutting out from the rock, while his bike cartwheels out of sight to the bottom of the canyon.

The Challenge: Your friend is clearly in a lot of pain and there's no telling how long the ledge he's on will hold, so riding the many miles out to the trailhead to call for outside help is not an option. And, as is always the case in these situations, your cellphone gets no signal out here. Bottom line, you need to figure out a way to get your friend, who weighs a good 30 pounds more than you, up off that ledge and back down the trail to your car before nightfall -- which is maybe four or so hours off.

What You Have: In addition to your bike, you've got your daypack, which contains a canteen of water, some protein bars, a basic bicycle repair tool kit, an extra inner tube, your Swiss Army knife or Leatherman tool, a strong, flexible, 3-foot wire saw with split-ring finger-handles on both ends, some waterproof matches, and roughly 30 feet of strong nylon cord you use to tie your bikes onto the car. Since you know from experience that you can't predict the weather, you also have some waterproof nylon rain gear and a warm jacket.

There are some small trees on the upper side of the trail but none immediately adjacent to the ledge where your friend fell. Though he's conscious, it's best to assume he can do very little to assist you in getting him off the ledge below, and he certainly won't be able to walk if and when you do. However, he does have enough strength in his arms to hang onto the tree branch, at least for now. So what are you going to do?

If duplicate solutions are submitted, the winner will be determined by the quality of the explanation and presentation. The most plausible and most creative solutions will each win a MAKE T-shirt and a MAKE Pocket Ref. Think positive and include your shirt size and contact information with your solution. Good luck!

For readers' solutions to previous MakeShift challenges, visit makezine.com/makeshift.

Here's what you're up against:

Tick, Tick, Tick ...
The Scenario: You've worked late into the night as a computer engineer in the high-rise headquarters of an international bank, and you're finally heading with your briefcase to your car in the subterranean parking garage. Your car is the only one left on this dimly lit level, parked along a cement wall right near the elevator. But, as you pull out your keys and are about to hit the unlock button, you hear a loud beep behind you.
Startled, you turn to see an object against the wall just a few feet away with a pulsing red light on it -- and in the poor light, you can immediately make out an illuminated timer which is now ticking off the seconds from a 3-minute window!
There is a jumble of multicolored wires, and an array of three motion detectors set to cover a 180º field off the wall, all of which are wired into a small black box sitting on a large brick-shaped object that's slightly smaller than a shoebox. Also atop the brick and on its ends, you see three horizontal glass tubes that appear to contain mercury with wires at both ends, as well as a metallic-looking cylinder with several long wires jammed into the side of the brick-like mass. There's little doubt left in your mind now that this is a bomb! -- and your arrival here must've set off the timer.
The Challenge: Though you know how mercury switches work, you're uncertain of the purpose of the motion detectors, or of the black box -- could it contain a hidden transponder? If you try to move out of range or call for help with your cellphone, might your attempt to flee or the cellphone signal set the device off? Hell, even pushing the unlock button on your key ring now could send the wrong kind of signal, no? But panic is not an option, as it seems you have less than three minutes to decide your best course of action. So what are you going to do?!
What You Have: Your briefcase and pockets contain what a computer engineer might normally have, within reason -- if that includes a Swiss Army knife or Leatherman tool, so be it. Beyond that, your brain is the best tool you've got. So think fast, and ... good luck.

The "Reuseum" is a mega-mart for all things Maker-Friendly. Based in Garden City, Idaho, this place holds tons of old and vintage electronic surplus and junk as well as hosts Maker and Circuit Bending workshops! Check out their site to find out what they have and their "EVENTS" page for more details on the workshops and classes

The Reuseum via GetLoFi

Finally reaching the end of the road in the middle of nowhere, you ask your partner to unload the car while you head for the rocks to survey the landscape. But as you climb through some old barbed-wire fencing to look for a trail, your keys - attached to your Swiss Army knife - fall out of your pocket and skitter off across the rocks before they disappear into a deep, six-inch-wide crevice between two boulders. (Don't you just hate when that happens?) Needess to say, neither your cellphone nor your OnStar system gets reception out here, and the fancy anti-theft option you went for makes hot-wiring your SUV all but impossible.

The Challenge:
Without transportation, you're stranded. To avoid the daunting prospect of walking back out to the main road - as well as "never hearing the end of this" from your mate - you're going to need to recover those keys.

The boulders are too massive to be moved in any way and you don't have a direct sight line to your keys. But you are able to ascertain that the depth of the narow crevice can't be more than 15 feet. It's about noon now, so you've got at least 6-7 hours of daylight to work with before it gets dark. Surely someone with your skills and ingenuity can get those suckers out of there in time to get you home safely, if not still salvage the outing, no? As the wheels start turning, your mate appears and asks, "Is something wrong, honey?"

Here's what you've got:
In addition to everything mentioned, there's a basic tool kit in the car: hammer, screwdriver, adjustable wrench, snippers, pliers, etc., as well as 100 feet of nylon rope. Because this is an old mining area, there may also be some small pieces of wood and metal lying around.

Send a detailed description of your MakeShift solution with sketches and/or photos to makeshift@makezine.com by Aug. 17, 2007. If duplicate designs are submitted, the winner will be determined by the quality of the explanation and presentation. The most plausible and creative solutions will each win a MAKE sweatshirt. Think positive and include your shirt size and contact information with your description. For rules and solutions to previous MakeShift challenges, visit makezine.com/makeshift.

MakeShift - Link.

The creator of MacGyver challenges you to survive on a deserted island.

There are few fears more primal than being cast away on a deserted island in the middle of who-knows-where. Maybe it's a throwback to our eviction from the Garden of Eden, or the nagging realization that Earth itself is just such an island in the endless ocean of space. Whatever the reason, it has been and remains a mainstay of the collective imagination.

The Scenario:
You are on a small sailboat in the South Pacific when a freak wave of Biblical proportions swallows your craft. You awake to find yourself on the rocky, sandy beach of--what else?--a tiny deserted tropical island. As the fierce equatorial sun beats down on you, you realize that the boat is gone, but a large section of the white, waterproof nylon sail has washed up on thet beach.

Relieved that you are alive and have sustained no major injuries, you quickly scout out the island. There is a cave for shelter, an abundance of vines and vegetation, but no trees to speak of. You see enough sea birds and marine life to provide a subsistence diet, but there is no source of fresh water! And the rainy season is still months away.

The Challenge:
Come up with a reliable way to produce potable water until you are rescued--or the meaning of life is revealed to you, and being rescued no longer matters.

Your items:
You have only the nylon sailcloth and what you were wearing when you washed ashore: a dark, waterproof windbreaker; a T-shirt; and shorts, in which you find your Swiss Army knife (or Leatherman tool) and a pack of waterproof matches. If it provides additional motivation, feel free to be cast away with the fantasy celebrity of your choice--but this person is still counting on you to provide drinkable water. And if you're looking for extra points here, forget the pack of matches.

Good luck, and rest assured that we're all out there looking for you.

~~~

Send a detailed description of your MakeShift solution with sketches and/or photos to makeshift@makezine.com by February 23, 2007. If duplicate designs are submitted, the winner will be determined by the quality of the explanation and presentation. The most plausible and creative solutions will each win a MAKE sweatshirt. Think positive and include your shirt size and contact information with your description. For rules and solutions to previous MakeShift challenges, visit makezine.com/makeshift.

Coming full circle, Woody is now the one throwing down the gauntlet, challenging you to prove your makeshift mettle by staying alive for 48 hours in a bank vault with limited oxygen. Over 100 of you answered the call, and Woody and I had to break open the engineering and chemistry texts to evaluate a good number of the submissions. In the end, Woody selected two winners and two honorable mentions; to say that selecting two winners from the pool of entries was difficult would be to understate matters. It was flat-out hard.

It is interesting to note Woody's unique method of evaluation. Before he would evaluate any of the responses, he felt like he had to submit himself to the challenge and solve his own problem. He even set up an electrolysis apparatus in his lab so he could get empirical versus theoretical measures of power consumption and 0/H production. Then, he used his solution and data as reference points to evaluate the entries. Woody's Solution is included here for your review.

Thanks to the MAKE readers who took up Woody's challenge - check out all the winners here! - Link.

What do you think, is this a worthy challenge?

Makers, are Mitsubishi's claims possible? Post up if you think orange LEDs will actually make your veggies better, ideas on how to do this and test it.

Pictured here, random meat from the "Meat Identification test".