sent in his entry into a “creativity contest” at his university. He and some friends put together this dry ice cannon. Take note of the creative mechanism they used to mix the water with the dry ice. A large amount of gas is expelled as soon as the two begin to meet. If the gas is supposed to escape through the same opening, it is difficult to get all the material through. They have added a second opening just for the exhaust during mixing. Great job guys. How about some downloadable plans.
The registration desk hasn’t opened yet at ShmooCon 2009, but we’re already running into old friends. We found [Larry Pesce] and [Paul Asadoorian] from the PaulDotCom Security Weekly podcast showing off their latest ShmooBall gun. ShmooBalls have been a staple of ShmooCon from the very beginning. They’re soft foam balls distributed to each of the attendees who can then use them to pelt the speakers when they disagree. It’s a semi-anonymous way of expressing your dismay physically. [Larry] has been building bigger and better ways to shoot the ShmooBalls for the last couple years. You may remember seeing the 2008 model. This year the goal was to make the gun part much lighter. The CO2 supply is mounted remotely with a solenoid valve and coiled air line. The pistol grip has a light up arming switch and trigger. The gun is fairly easy to transport: the air line has a quick disconnect and the power is connected using ethernet jacks.
For those who use these little cartridges, you know how quickly the price can add up. [steve] takes us through the process of adding a valve to a spent cartridge so it can be refilled. Over all, it doesn’t seem too difficult, and [steve] offers lots of tips to increase longevity and reliability. It isn’t very often that we show a hack here that doesn’t involve some kind of electronics, so take a break from the resistors and microprocessors for a moment and enjoy.
We all remember the diy cnc laser. In my quest to bring you guys fresh stuff, I found an interesting design (the author says he built his in the 80s) for a home-built CO2 laser. The dimensions are missing, but the design is pretty simple. If you like some textbook style reading, the hyperphysics server is your friend. I finally bought a mini mill to go with my lathe – this could make an interesting machining project. Get a mini-fridge compressor to for the vacuum source, and the gas is easily acquired from the local welding shop. I’d bet Surplus shed probably has some workable optics.
The 25th is the deadline for the Design Challenge. Don’t freak out, just get it submitted before I get up on the 26th, and I’ll call it good.
