It's actually fired remote trigger and it's mounted vertically with me handling both the loading and the charging. I also have smaller pneumatic guns with electric valves that the kids shoot but we keep the pressure low on em and they are far heavier built for kid-friendly-ness.

-Mike

It's fixed now. Wow, what a monster. It's shooting flour 2x the height of my house! Thanks much for the help, the combination of tighter piston and less travel/volume behind it totally fixed the problem. Anyone in the KC area should head to the Maker Faire at Union Station and you can fire it off :)...

As opposed to adhesive fillers, I would try wrapping the piston in masking tape or duct tape, so that if you get something wrong at least it's easily reversible. Before I posted here for help I tried this. One layer of duct tape wasn't enough and two was too much. I'll be sanding the piston this mo...

Are you sure the sprinkler valve is goin the right way? Yes. try upping your pressure 10 psi at a time up to 70 you may need more pressure to actuate it. It actuates fine. The air rushes out of the valve as expected, just not out the barrel. Are you filling through your pilot valve? No, I plumbed i...

Hi all; I'm desperate for a quick fix. I'm exhibiting something kinda like this at the Kansas City Maker Fair this year: [youtube]http://www.youtube.com/watch?v=K73s4MRJSzc#![/youtube] I did this last year using my modded sprinkler valve gun and it worked great. I was about to get fireballs about 20...

I put it here because it's pneumatic only but if how-to makes more sense, I'm sure a mod will go ahead and move it

Sorry to revive a little older thread, but when I read this I saw that the math is a pain and the question comes up a lot so I did my best to answer it in a post here.

Since this community has been so helpful, I wanted to give back what little I could. This might be obvious to all of you but it wasn't to me so I figure I'd post it for people to see. I'd love to claim credit for the math but I had one of my friends help me with it. I'm just posting it as he explain...

Ok, so thanks to advice and input from the group, I've started churning out guns for friends that work well and are nice and safe/sturdy. I've got it down to a minimal amount of materials and time to build with one annoying exception: the barrel supports. Currently I'm using a jig for my router made...

Thanks for all the nice comments and suggestions! It's a good thing that you plan a barrel support on your next launcher, it reduces material stress points and increases accuracy. Actually, the video doesn't show it, but gun #2 has barrel support now made out of some MDF and a large hose clamp that ...

This is my second cannon. Nothing exotic. I used 2" for the chamber to keep the price and parts availability nice and easy as 3" pressure rated fittings seem hard to find in my area. I extended the chamber right up to the sprinkler valve by putting a 2" to 1" reducer bushing right into the elbow. Th...

P.S. If it was a Plumbing Expert and not a floor associate, then they probably do know what their talking about considering they have to be licensed. Heh, we are talking about Home Depot here, I doubt he was a licensed plumber from his responses. But it also depends on what kinds of pressure you're...

Hi all; I'm a little confused and getting conflicting answers. I've been using the "purple primer" stuff from Oatey (what Home Depot and Lowes both sell) combined with medium weight PVC cement and I'm sick of the purple gunk everywhere. I went to the store to see if they had some white or clear prim...

Look better, because its done that way on almost all well-built cannons and is always recommended. Its safer, more leak-proof and stronger. Sorry, I didn't mean to sound like I was arguing - just that I'd not seen it very often before. I have some plans from http://www.myaircannons.com/ and none of...

Thanks for all the advice and comments. I'll work all this into my next gun design. One question though: -When threading the shrader valve through the PVC (or anything else, like the popoff) make sure to thread through TWO layers of PVC. This would be where a fitting joins with a piece of pipe. I fo...