I built it! I decided to save myself the trouble, and went ahead and bought a 1/2" QEV valve!



It shoots batteries through old scrap doors! Now I need to get a better compressor...

Hi All! Couple quick insights: balloons don't work, sadly...It needs to be a rapidly rising projectile. I had that thought before though! Also, the bb idea is great. I'm not sure how it would work in practice though....It'd be amazing to see! Here's a surface-level overview "guest lecture" that I fe...

Aw, heck...why not? Might as well get a blowtorch head. It'll come in handy someday anyways!

Fill the tank with water then empty it before taking any tools to it! . . . How don't they line up exactly? different number of threads per inch? What pressures are you planning on running at? For a small bore and heavy projectile, you,re going to need pretty high pressures to reach the sort of alt...

I just emptied the propane tank....And subsequently froze a large section of ground in my back yard....Pretty Dramatic! Once I'm 100% sure the thing is empty, I'm going to drill out the top valve tonight by using a drill press and slowly increasing the bit size. For the piston, I'm planning on filli...

to attach your string you may want to have a spring attached to your projectile so that the initial stress does not break the wire. Pure Brilliance. You all really know your stuff, and I don't think I ever would have thought off that! That will probably save me a headache and a half. :D Now, the qu...

Hi All! I'm planning on assembling my first piston air cannon very soon. I just had a few safety concerns before I move forward. My planned layout is as follows: http://i886.photobucket.com/albums/ac68/_insert-name-here_/20131101_013542_zps8cece9d4.jpg (Cannon will be pressurized from the vertical e...

Based on the responses here, I think I'll probably use something like a steel arrow, with the line consisting of my kevlar wound copper wire from the rocket part of the project that I've already done. I'm headed out to buy some hardware tonight!

Hi All! Long time lurker here. I've been interested in potato cannons (mostly pneumatic) for some time now. I'm also interested in lightning. I'll spare you any other long-winded introductions and cut to the chase. I've been working on a project for some time now ( ~2 years), attempting to somewhat ...

My first metal gun I've created. It's all a product of having too much time on my hands after a day of mid-term finals. Specs: Barrel: length: 6" long, 1/4" diameter Pressure chamber: 4.5" long 1/2" diameter Valve: 1/4" ball valve I was wandering around the hardware store, and I was looking to creat...

that's an awesome cannon. I'll have to look into getting some metal parts soon. thanks for the inspiration

So, I've been tossing the idea of making a hydrogen powered spud gun around in my head for a while, and I've even made a few prototypes, but they never seem to be reliable. Making a mini cannon seemed to be my only reasonable way to go about this for three reasons: 1: less hydrogen takes less time t...

Yea, I didn't see any movies.

there ya go...movies...nothing great (probably not worth your time)

Nice paint job, light job, everything job
hint: you might want to post the videos on the original post, so people that are not smart enough to scroll down will see them

hehe don't get mad get glad, I like it, make a better one, the valve is the only expensive part.

not mad, just pointing out why it sucks I'm looking forward to making a new one