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The Concrete Breaker

Built a pneumatic cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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The Concrete Breaker

Unread postAuthor: cardman625 » Sat Jul 26, 2008 8:15 pm

This is my first post and latest cannon

specs:
8ft x 2in sch 40 barrel
5ft x 3in sch 40 tank
full 2in port piston tee valve triggered by a modded rainbird sprinkler valve

Ill post a video soon breaking some cinder blocks with a potato
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Attachments
cannon.jpg
DSC02557.JPG
DSC02558.JPG
pic of the valve assembly
valve.JPG
valve schematic
valve.JPG (18.08 KiB) Viewed 1642 times
Last edited by cardman625 on Mon Jul 28, 2008 12:40 pm, edited 2 times in total.

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Unread postAuthor: SpudFarm » Sat Jul 26, 2008 8:20 pm

heck! that thing is big! simple tho - and thats how we like it!

we really need some videos of this thing
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Unread postAuthor: Maniac » Sat Jul 26, 2008 8:21 pm

WOW that is a nice cannon. How many cannons have you built before this one it looks really nice. It looks like you did you research on this, did you do design it by your self? Yay I spy no DWV on your cannon thumbs up :D.
Welcome to the site and hope to see more good work from you. :P
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Unread postAuthor: cardman625 » Sat Jul 26, 2008 8:34 pm

thanks, ive built so many ive lost count and Lowe's is always happy to have me in their pluming department

As for the design its mostly based on the materials i could get my hands on.
The real beauty of the design is the extended tee that lets the piston travel father back opening a full 2inches and man this thing is powerful even at 30psi its got some kick!
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Unread postAuthor: Sticky_Tape » Sat Jul 26, 2008 9:37 pm

Uh oh D/4 nazis are afoot.
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You can tell how awesome a cannon is by the pressure used.
http://www.spudfiles.com/forums/high-pr ... 12803.html
xnt rnm ne z ahtbg
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Unread postAuthor: MrCrowley » Sat Jul 26, 2008 10:00 pm

To explain what Sticky_Tape means (S_T, don't post such useless replies, he probably doesn't know what you are talking about, explain yourself in the future)...

The D/4 rules applies to co-axials ONLY *rolls eyes at S_T*.

Anyway it roughly calculates how much 'travel' your piston needs to open to achieve full flow. You want to limit how far your piston can travel back to cut down on pilot volume (wasted air pretty much) but you don't want to cut down too much and limit your flow.

In barrel sealers we generally use D/2, which means barrel diameter divided by 2 gives us the maximum distance the piston should travel back.

Though in chamber sealers it's a different story depending on where abouts your pistons seals against the chamber in the tee. 1" travel is probably enough for the piston but I can't say for sure.
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Unread postAuthor: mobile chernobyl » Sat Jul 26, 2008 10:44 pm

Haha I think you have the exact same "gauge, "T" , air inlet valve" assembly I have on my "1 gallon gun" down to the "T" litterally. Works good, and is compact, can't complain with that.

Thats pretty impressive if your breaking the cinder blocks with a POTATO. One question tho - What kind of cinder block? Post a pic of it if you can (pre carnage state) cause my last "big gun" was a coaxile of similar proportions to your "concrete breaker" gun and it had trouble breaking cinder blocks with anything but a piercing projectile (which it would almost leave 2 clean holes in a cinder block, just barely cracking the rest of it.) So i'm just wondering if I was shooting at a super reinforced cinderblock design, and your shooting at the standard 2 void cinder block. Thanks

Oh and partially the reason your gun has noticably more kick than w/e at just 30psi is because of your excess piston throw. It's allowing the piston to build up more momentum, and when the piston stops the momentum tranfers into who's ever holding it. If you don't believe me - shim your piston so it only travels 1" and you will notice a drop in recoil, but hardly a noticable drop (if at all) in projectile exit velocity.
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Unread postAuthor: Hotwired » Sun Jul 27, 2008 1:55 am

MrCrowley wrote:In barrel sealers we generally use D/2, which means barrel diameter divided by 2 gives us the maximum distance the piston should travel back.

Though in chamber sealers it's a different story depending on where abouts your pistons seals against the chamber in the tee. 1" travel is probably enough for the piston but I can't say for sure.


Well with that kind of chamber seal it does need at least 2" of travel to fully expose the barrel port.

Using a fatter valve body and an unconventional design can give you a chamber sealer that has between d/4 and d/2 travel though.
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Unread postAuthor: MrCrowley » Sun Jul 27, 2008 2:02 am

Hotwired wrote:
MrCrowley wrote:In barrel sealers we generally use D/2, which means barrel diameter divided by 2 gives us the maximum distance the piston should travel back.

Though in chamber sealers it's a different story depending on where abouts your pistons seals against the chamber in the tee. 1" travel is probably enough for the piston but I can't say for sure.


Well with that kind of chamber seal it does need at least 2" of travel to fully expose the barrel port.

Using a fatter valve body and an unconventional design can give you a chamber sealer that has between d/4 and d/2 travel though.

That's why I said it depends on where abouts the piston seals, if the chamber extends all the way to the edge of the barrel port, then 1" might be enough as if it had 2" travel, all the air may have already been gone by the time it's fully open.

I'm not totally sure though, it would be interesting to know if anyone out there has some figures.
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Unread postAuthor: starman » Sun Jul 27, 2008 2:12 am

I missed this one yesterday. This thing looks like a real brute. Even though the pilot and meter hoses could be tightened up some, it has a nice technical look to it.

This is a very nice cannon. Lots of power, decent design. We're eagerly awaiting the concrete breakage.... :wink:
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Unread postAuthor: jackssmirkingrevenge » Sun Jul 27, 2008 3:35 am

Sticky_Tape wrote:Uh oh D/4 nazis are afoot.


Not today, hangover ;p
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Unread postAuthor: Hubb » Sun Jul 27, 2008 6:17 am

Beautiful. I love a powerful cannon. I've experienced "cement shatter" before. It's a glorious sound :twisted:

The only complaint I have is I'd like to see more specs and some internal pictures.

Nice job. Welcome to Spudfiles.
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Unread postAuthor: mark.f » Sun Jul 27, 2008 9:31 pm

Not only are the D/4 nazis not afoot, they would be pwned anyway, because that looks like a chamber sealing valve!

We need more posters like you, cardman. First post is a finished chamber-sealing piston valve (if I am correct in assuming the valve is chamber-sealing). If it's not chamber sealing, I'd be interested in some pictures of the valve internals (I'd be interested anyways as well).
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WIP: belligerent mixture of steel and pressurized reactants
COMPLETION: several months out
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Unread postAuthor: stevenarroyo » Thu Jul 31, 2008 6:58 pm

i need to see videos of that thing firing!
it looks like you can make things go bye bye very very fast.
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Unread postAuthor: mark.f » Thu Jul 31, 2008 10:44 pm

I know I already posted, but after you posted that diagram, I realized a few more things I liked:

1.) The simplicity of your design. It has been reduced to the purely critical, which I like. Not a lot of time has been spent fretting over how it looked. Also, equalization is uncomplicated and very effective between the pilot chamber and main chamber. Instead of working on some sort of one-way equalization flow through the piston, you slapped on a manually controlled external equalization system.

2.) You have really stepped away from the stereotypical chamber-sealer, like the Supah valve, in the simplicity of design and lack of aesthetic worries. Good job.
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