First* cannon - piston valve

[aEx155]

So, I did a lot of research (and still am) because I wanted a really good air cannon. Anyways, after all that research, here's my first post.

*The first cannon I made was a ball valve cannon with a .5 liter soda bottle as an air tank. It shot NERF darts for my physical science class.

After messing around with ball valves and such I looked into building a coaxial. It worked pretty well, except for the fact that it started tearing its sealing face at anything above 120 PSI, and I couldn't breach load.

I call this my first cannon since it's really the first, fully functional, sturdy air cannon I've made.

Info:

Barrel: 1/2" x 2'
Chamber: 1-1/4" x ~8" (maybe a little more)
Valve: 3/4" inside a 1-1/4" tee

<table><tr><td align="center"><a href="http://picasaweb.google.com/morphingrob ... site"><img src="http://lh4.ggpht.com/_aBXfV0GXozg/Sy7rM ... Cannon.jpg" width="160" height="160"></a></td></tr><tr><td><a href="http://picasaweb.google.com/morphingrob ... bsite">Air Cannon</a></td></tr></table>

I'm amazed how well it works, but I'm not exactly surprised since R/D for all my air cannon adventures must be well in the $100-$200 range. Most of it was spent on buying parts for piston valve prototypes.

Anyways, more details.

It's a barrel sealing piston valve with 3/4" ports inside a 1-1/4" tee. It's piloted by a slightly modified hose handle and filled by a schrader valve.

Currently it operates at anywhere from 40 to 140 PSI, depending on what I'm shooting. So far I've shot stock and modified NERF darts and nail darts (my own variety) [1/2" barrel] and EXPO whiteboard markers [3/4" barrel]

The piston is made out of a 1"x1/4" bolt through a filed down 3/4" endcap (I used a drill). The sealing face is a 1-1/4"x1/4" neoprene washer sitting on a fender washer of the same size. It also has an o-ring for maximum performance.

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If my dad ever lets me continue with this hobby (he won't let me buy any more parts because he's said I've built too many (3, including this one)), I really want to make a more compact piston valve with 1" porting (pretty much a stinger valve) but without the female adapter on the end. Another project in the design stage is an over-under with a toolie-piston, but that might get its own thread.

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Anyways, hopefully this post isn't too long Please rate; comments and suggestions appreciated!

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[bradisfun]

very nice my dad was like that with my first canon (i spent $150 with no prototypes) but then i showed him what it could do and he got interested in the habby aswaell but he wont take it online.
mabey u should try to get ur dad interested in it or show him what he wants to see like if u have a brother u could turn down the presher and play nerf games or evan with a friend and then invite him to play.
but very nice gun,do u have any photos of the piston?

[jackssmirkingrevenge]

Looks like you found out about the need for a bumper the hard way



Very nice for a first effort, as to paternal disapproval ask your dad would he rather you spend your free time drinking/smoking/having disappointing sex* with other teenagers, or actually indulging in an inspiring hobby that will eventually make you very adept at domestic DIY

*if you play your cards right, you'll find time for everything

[aEx155]

very nice my dad was like that with my first canon (i spent $150 with no prototypes) but then i showed him what it could do and he got interested in the habby aswaell but he wont take it online.
mabey u should try to get ur dad interested in it or show him what he wants to see like if u have a brother u could turn down the presher and play nerf games or evan with a friend and then invite him to play.
but very nice gun,do u have any photos of the piston?

My dad actually knows what it can do (I actually do a lot of other hobbies so it gets pretty hard to surprise him). He just thinks that it's pointless and dangerous, so I don't know.

The one picture up there is a link to a Picasa Slideshow, , but I put them on Photobucket as well:

Looks like you found out about the need for a bumper the hard way

I knew I would need a bumper, it's just that I underestimated what kind I needed. I had this crazy idea that my piston was bouncing off of the rubber hose bumper I was using (it's the one currently in use), so I tried it with just that big o-ring in the picture there. It didn't work, twice (the PVC fragments in that picture are from when I tried the idea again by stealing the piston off of my coaxial)

Now I use a piece of blue foam and a piece of rubber hose (like in the current pictures).

[Willdebeers]

I like your piston setup, it kinda reminds me of this> http://www.youtube.com/watch?v=vpy-7l1oKLM

[bradisfun]

yeah i mean like let him use it and just try to get him interesed in it
i do lots of other hobbys to(reefing,moto riding,gameing and downhilling!, yeah thats a lot of hobbys) but i still found sum thing that he liked about it he still thinks thats it's heaps dangours,the thing i found that he liked about it was competive part like trying to beat be at makeing a faster opning valve! i dont what u have to do no but if u can get him interested then u will have a lot more money to play with!

[drac]

@jackssmirkingrevenge, what's wrong with dissappointing sex? hehe

It's a hell of a nice gun, very well thought out. Glad to know you share a passion for the hobby. And man, I have over 20 working cannons, and have 4 in the works. You can never have too many spudchuckers. Tell your dad you'll help him build one, that'll change his mind. Worked with my dad, haha.

[jackssmirkingrevenge]

@jackssmirkingrevenge, what's wrong with dissappointing sex?

nothing at all, hence the footnote

[drac]

Hehe, ok, enough hijacking.

[aEx155]

I was firing some center punches and bolts in hot glue pistons yesterday afternoon into a piece of 1/2" plywood:

160 PSI, ~4' barrel




All the larger holes are from bolts or center punches. In the last picture I still haven't gotten that punch out yet.

Unfortunately, my dad has banned the firing of anything metal or sharp. So he got mad at me for trying again. Oh well. I guess any new developments aren't going to be made for a while.

[jackssmirkingrevenge]

Unfortunately, my dad has banned the firing of anything metal or sharp. So he got mad at me for trying again.

Well they are spudguns, vegetables can be fun ammo too

[Hubb]

****

There is always room for improvements, but this is very nice for a first piston launcher.

[aEx155]

A bit of convincing (I said it would be a less dangerous version) and my dad let me get some more parts. I'll stick a link up here when I get the new thread started.

[bradisfun]

SWEET cant wait!