Thursday, February 28, 2008
Thursday, February 21, 2008
Monday, February 18, 2008
He experimented with various painting techniques that could
harness natural forces: blowing a fan over thinly applied paint on canvas; blistering a thick paint surface with heat; coaxing a dove to walk through green paint and onto a picture. More fruitfully, in 1984 he began to use the ancient Chinese invention of gunpowder — beginning by shooting fireworks at a canvas and then, for more control, developing a method of unrolling firecrackers, sprinkling the powder on canvas and igniting it. -- Arthur Lubow in the New York Times
Wednesday, February 13, 2008
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. They would make a very good entry in a science fair or science contest. For ideas on catapult related science fair projects, check out "The Art of the Catapult" and "Backyard Ballistics," available at book stores everywhere. (Click on the Amazon link to the books above for more info) Believe me, there is plenty of physics and math behind the machine for cerebral types.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. You can follow the links below to obtain high quality, inexpensive catapult release trigger mechanisms that should work well for most small experimental 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.
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.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.
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.
Tuesday, February 12, 2008
I am going to attempt to monitor several of the most active DIY science and technology sites for the next several weeks to get an understanding on which sites provide the best ideas for projects. Some of them post new stuff constantly, but the projects are mostly "unfiltered".
Some, like the Make blog have so much good stuff, it's an overwhelming task to sort the interesting from the pedestrian projects. So what I want to do is pick and choose and post about the few that regularly have excellent, doable projects.
Today, I found these on my newsreader:
On the Hacked Gadgets blog, there's a project that uses balloons to take pictures from the sky. It's very reminiscent of the Kite Cam found in Make Magazine issue #1. Video of the red balloon project is available here. Separate but related information on making balloon mounted cameras is available here.
On Etsy's site, my friend Bre Pettis (he of imakethings.com) returns to the video world with a short video on how he's making his new business cards. It's not really a science or technology project, but it's good to see he's back.
On Street Use, Kevin Kelly shows just how far people can go, using the materials around them to meet their mechanical needs. I like this because I've done some research on the abilities of Aborigines, Cubans, and Eastern Europeans to scrounge parts and keep things moving out of baling wire, hose clamps, and bungie cords.
On Windell Oskay's Evil Mad Scientist laboratories, there's a very good post about making a pegboard LED display that makes it simple to paint with LEDs, maybe not as simple as light-brites, but sorta simple. By the way, the VD in the "Happy V.D." picture refers to Valentines Day.
If you know of good DIY science and technology blogs that at least occasionally post good projects, please let me know.
Thursday, February 07, 2008
This is excerpted from my recent article in Make Magazine. Is there a problem with the way science is taught? Are schools overprotective? What do experiences like these mean for science education?
When my son Andy was 12 years old, he entered his junior high school science fair. His challenge was to invent something new and useful. To Andy, the science contest was big deal. There was a great deal of schoolyard prestige attached to the event. He badly wanted to win, but inventing is hard work. Inventing something useful is even harder. And inventing something new and useful when you’re 12 is really, really hard.
He thought about it for a while and, after various aborted attempts and blind alleys, came up with the idea of a self-buttering toaster. What a brilliant idea from such a young person! (I readily admit my fatherly bias.) The device Andy designed was intricate yet simple: a wood and steel construction that held a slice of bread at an angle in front of a carefully wound matrix of nichrome wire heating elements. While the bread toasted, the heat from the wires melted a glop of butter on a perforated metal holder positioned over the bread. The butter dripped through the holes and on to the toasting bread. Voila! There was a slice of automatically buttered toast. By my lights, this was a pretty terrific invention for a sixth grader.
The evening of the fair approached, and Andy and I looked forward with anticipation and excitement to a night of glory. The judges, a collection of teachers and parent volunteers, methodically walked up and down each aisle. They asked questions, measured things with rulers, made notes on clipboards, and generally maintained a judgelike demeanor. When the judges came to Andy’s table, the toaster worked perfectly. With self-assurance and a smile, he handed each judge a slice of warm, buttery Wonder Bread for a snack.
The Self Buttering Toaster ---->
But when the winners were announced, Andy’s name wasn’t called. Crestfallen, he approached the judges and asked, “Why didn’t I get a ribbon?”
“Well, Andy,” said a judge, “we thought your machine was dangerous. After all, it uses electricity and it gets very hot.”
“Of course it does. It’s a toaster,” he protested. “It’s supposed to get hot and use electricity. If it didn’t, it wouldn’t be a toaster.” Unswayed by logic, the judges would not reconsider.
So who won? First place went to a girl who made a cap and vest for her hamster. Second place went to a boy who “made” radar.
“Hamster clothes? That’s so lame,” Andy whispered to me during the award ceremony. “And that the second place kid didn’t invent radar. He just cut out some pictures of radar antennas and glued them to a poster board.”
[Life imitates art: In the 4th season episode of the Simpsons called "Duffless, " Nibbles the hamster plays a significant role in the outcome of the Springfield Elementary science fair]
<--- Bart Simpson science project: Can Hamster Fly Planes?
Andy graduated from college last year with a major in archeology and a minor in African languages. Is his technology-light choice of major a result of his science contest experience? Perhaps not, but I sometimes wonder how losing to a hamster hat influenced his future.
Tuesday, February 05, 2008
Two of my good friends have their own blogs which I find very enjoyable. So I was certainly pleased to find that these two have decided to collaborate to form a digital media conglomerate. It's called Dinosaurs and Robots.
<---Mr. Jalopy on Cover of Make Magazine
To be honest, I can't figure out where Make Magazine cover boys Mark Frauenfelder (of BoingBoing) and Mr. Jalopy (of HooptyRides) find time to turn out such a good looking magazine. I guess they figured that since they were both on the cover of Make Magazine, it was time to move on to something bigger. Reminds me of when Wayne Rogers left MASH and Patrick Duffy decided he was too big for Dallas.
The first issue of D&R is available here. (I sometimes call Mr. Jalopy "J-Lop" (like J-Lo, get it?) for short but he really seems to dislike that. )
The new magazine is currently available as a downloaded pdf, but I understand plans are underway for a website. I checked it out and loved the articles but it's the photos that really clicked with me. There's a recurring theme dealing with the intrinsic beauty or at least pleasing geometry of tools and metal objects.
----> Mark Frauenfelder on cover of Make Magazine
Visit hooptyrides.com and read the blog for more info.
Sunday, February 03, 2008
This post is about the air whistle, (similar to a steam whistle) I designed and wrote about in the last Make Magazine.
This PVC whistle is based on a calliope design that provides a lot of noise at relatively low air pressures. I called it the Super Tritone after a train whistle my friend Steve Cox owns, which is called a Leslie Super Tyfon, (although technically, the Super Tyfon is a horn, not a whistle.)
There are several good articles in Make Magazine #12, the latest issue. I’ve contributed three, including a major project called the Super TriTone Shop Whistle. I’ve written and photographed step-by-step directions showing how to make a really neat whistle from PVC pipe and fittings. If you don’t subscribe to Make Magazine, try to locate a copy. You can subscribe online to this wonderful magazine here.
If you sign up using their autorenew feature (no big deal, you can always cancel) you will get online access to all of Make’s voluminous archives of projects including this one. That's a good deal, believe me. There's a lot in there.
Adjusting the Super Tritone Shop Whistle
The Super Tritone is easy enough to make, see the Make Magazine article for details. But be forewarned -- it takes a while to adjust. There are a number of critical dimensions and if any of them are off, the whistle doesn’t sound, it mostly just hisses. However, adjusting the Super Tritone isn’t that hard, mostly consisting of turning the adjusting nuts on the main shaft, thereby making the whistle throat larger or smaller. At some critical dimension, it will provide a loud shrill tritone.
Next, look at the alignment of the bells (the larger PVC pipe with the edge filed into the bottom) with the opening through which the air passes. The air opening is an annular slit, formed by the PVC bowl and a slightly smaller plastic disk called the languid. The placement of the languid is critical.
In connection with that, you’ll need to turn the horizontal adjusting screws on the bell and the bowl to make sure the air escaping the languid goes straight up into the edge on the bottom of the bell.
Finally, use enough air pressure. You’ll likely need 50 psi on up to get a really good sound.
Whistle physics is tricky and therefore, so is making your own whistle. But with enough adjustment and experimentation, your whistle will sound great. Be sure to read read all disclaimers and warnings in the magazine before you start.