This weekend I was carving pumpkins with my girlfriend. Pumpkin carving, a soothing time to bond, relax, and justify having power tools. Rather than hacking away at a pumpkin with a dinner blade, my trusty jigsaw and dremel did most of the cuts and an exacto knife detailed. It was much less effort and the pumpkins came out great.
Being me, I wasn’t settled with a mildly dangerous tea candle. I upgraded the wick by adding part of a regular candle. This made the pumpkin burn with a much more ominous glow (Harzard +1).
It was good, but not great. I went down to the shop and bore a hole into the back of the pumpkin. Add one spray can and that brought the pumpkin from seasonal fire hazard to double fisted spray can/fire extiguisher dangerous (Harzard +3 Safety +2).
In hind sight I should have bore the hole larger. Why? Well the fuel I’m spraying there tended to puddle up in the opening and set the pumpkin on fire, thankfully the pumpkin was fresh and still moist.
No it’s not a stargate, believe it or not it’s a bladeless fan. This fan blows a stream out of the blue ring. The blue ring has a special airfoil shape that can magnify the airflow up to 15x. Since it involves no blades this stream is uninterrupted. This fan seems pretty cool (if $300 means nothing to you,) if you ask me I’ll stick to my propellor style fan. Mine comes with soothing fan noises and doubles as a sound effect generator.
It certainly has the wow factor, but hackaday.com pointed out it probably has blades in the bottom to push air into the ring. Perhaps not the same traditional style but blades still. This design is very novel, so as far as the user is concerned it’s bladeless. It’s like buying a Roomba and realizing it needs to be emptied every once and a while.
Dyson also developed the Airblade hand dryer (the funny looking one you place your hand into and pull out slowly.) Plenty of videos on their site.
Matthew Shieh created this very interesting audio meter. Instead of the typical LM3915 VU meter, Matt designed the amplifier to capture ambient sound from a small mic. For the interface he used a photoresistor and capacitive touch button controlled by a PIC16F716 . The photoresistor lets him dim the LEDs when it’s dark to save power. His project really shines in the write up and best of all fits into a petridish.
Chris linked me to this video, it’s a vortex cannon on steroids. When a spherical mass of a fast moving fluid moves through the air, it can form torroid shaped vortex rings, similar to blowing smoke rings. This helps the mass stay together as it moves through the air so its almost like an invisible ball of air.
Lionel Oliver has an amazing site documenting his experiments metaling and casting metal. He shows how to build a variety of furnances from a simple charcoal furnance out of bricks and dirt to more complex propane furnaces. The best part is he does this all in his backyard.
Once you can melt metal you can start recycling old things like aluminum cans or lawn chairs and forming real tools and parts.
Ilya, (one of the other editors) informed me the other day of how he found my Spanish clone. Turns out somewhere in Canada there is an electrical engineer named Carlos who hosts a pretty cool project blog Carlitoscontraptions.com. A lot of his hardware projects match ones I’ve done in the past.
I’m particularly a fan of his Iron Man repulsor gauntlet. It allows a lot of freedom in motion and it lights up as he bends his wrist. He has really good pictures and a video of it here.
I have my own side project replicating the Iron Man Wrist Rocket. Its on/off because I’m using CO2 cartridges to fuel it and I’ve shot them all. Perhaps if I ask nicely, Carlos will want to collaborate. We can use his for the left arm and mine for the right… now all we need is an arc reactor…
Air Cannons are amazingly fun to play with at BBQs. Its really just my adult Nerf gun. You just fill the pressure chamber with a compressor and then hit the valve and watch the thing go. My normal projectiles are confetti, fruits, stale dinner rolls and glow sticks. I usually fire a couple shots of water to clean the cannon. The water shots make a really cool rain effect and feels great in the summer.
What about Explosive Cannons?
I used to build spud cannons powered by hairspray and starter fluid when I was in boy scouts. They are definitely more portable because you don’t need an air compressor and it’s a faster reload than a bicycle pump. They are half the cost too.
I finally got sick of the inconsistencies and went air powered. With gas powered some would never fire, some would fall short, some would even ignite the PVC on fire. Air powered gave me a measurable force and the extra cost was well worth it.
This video is NOT MINE! It does display the reason why I don’t like Combustion Cannons
Is it Safe?
If you know what you are doing Air Cannons made from PVC pipes are generally unsafe. If you don’t know what you are doing, then well, adios, nice knowing ya. PVC by any respected engineer is not a good pressure vessel, it’s easily damaged when dropped, brittle in the winter, and if it does not fail, it becomes a pipe bomb with PVC shards with you right next to it. Schedule 40 pipe can be rated around 200+psi. As a safety margin I usually pressurize my cannons around 75 psi. I used a tire valve stem to pump air in and it tends to leak at higher pressures so I don’t wish to break it. At 75 psi my cannon turns a solid apple projectile into pure sauce.
My Portable Party Cannon
I made a smaller version of the big one for parties. It’s the same cost as the big one ~$36, but the benefit is that it can be powered by a bicycle pump rather than a full compressor. I also added a solenoid sprinkler so I can add a remote in the future. Below are some photos.
This one is the miniaturized version, instead of using a 1″ manual valve. I used a sprinkler valve from Home Depot. I am hoping to one day build some electronics for this and make it remote. I built it in an hour for parties to launch confetti.
That black electrical tape is to hold three sections of pvc around the cannon as a tripod. Air goes in from a bicycle pump from the tire valve stem on the right. It takes about 20 pumps to hit 35psi for confetti.
Streamers are usually inexpensive ($1 a roll) and they are fire retartant. It takes 1/3 of a roll to fill the barrel. I cut the streamers into 1″ x 0.5″ sections of confetti and cram them down the barrel. If you make it too small it becomes a mess to clean up.
The barrel on my design screws off so I can load multiple barrels and the change the size.
This manual bypass on the solenoid valve works well enough till I rig up a remote system.
How to Build One
There are some really complex designs out there, but if all you want is a big BOOM!, smirk and “Holy Crap that’s Awesome!” I recommend a compressed Air Cannon with a simple 1″ valve.
(SpudFiles) has plenty of research and forums on the topics, so there is no need for me to reinvent the wheel. Spudtech.com also sells a lot of the parts you wont find in Home Depot, like clear PVC and 125psi safety valves.
Other People’s Videos
I’m crazy about not having accidents with my cannon, but I can’t say the rest of the internet is. Here are some fun videos of people without the same philosophy.
One of the happiest moments backs as a Teaching Assistant in college was when a Professor told me to build a underwater autonomous course under $1000 and out of Lego Bricks.
There are a lot of things to over come if you are building one. But its not impossible to build a pretty intelligent Lego submersible. Especially when they are now digital with microcontrollers and sensors. One of my favorite examples was when Rhode Island University Beat MIT’s AUV with their Lego version.
Perhaps if I ask nicely, Carlos will want to collaborate. We can use his for the left arm and mine for the right… now all we need is an arc reactor…
