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CBHV: Masterclass entry

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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Unread postAuthor: jackssmirkingrevenge » Fri Sep 02, 2011 5:03 am

Brian the brain wrote:Although a large boom would have re-assured me the valve was doing what it is supposed to... :roll:


No, that would have meant it's doing more than it's supposed to - though I guess in Btbworld, overkill is expected, nay demanded :D
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Unread postAuthor: Brian the brain » Fri Sep 02, 2011 2:00 pm

I disassembled the valve as I said I would, for the picture.
As I did I noticed that my quest for power has led me to hammer the valve excessively.
The bulletnose had knocked forward and on the return the O-ring on the piston had popped out.
I'm sure glad I took it apart.

Last evening I had been testing it without the " balance" effect!

The silent shots where a result of the valve working like a regular hammervalve.
The counter piston was no longer effective and the valve shut very quickly.

I feel stupid for not noticing the difference. :roll:


Anyway....I replaced the damaged O-ring and put the valve together again.
It's working fine.
I've now learned that hitting the valve really hard is counter productive.
:oops:
Now gentle taps give much better shots.

I tried a lead slug and it mushroomed on the inside of my old 2" valve from my Mr Porter cannon.
This was at 45 pumps
I shot into the elbow so I'd be safe from ricochet.

Funny how I find myself counting pumps without even building up a sweat..as a measure of controling the pressure rather than monitoring a pressure gauge while sweating in fear..
:P
Here's the blurry valvestem pic.
I tried with the cam on " focus" but it was too dark.
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Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: POLAND_SPUD » Fri Sep 02, 2011 2:52 pm

I tried with the cam on " focus" but it was too dark
or you used cheapo batteries :D

Me want a video! ohh and show how you pump it up - I'd like to see how much effort that requires
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Unread postAuthor: Brian the brain » Fri Sep 02, 2011 3:05 pm

You dirty man you!

:D
I'll make a vid when it's done.
Pumping is easy.
And the handle is not even that long..

But that doesnt mean a thing If I don't know what pressure I'm reaching..

The barrelport and breech are threaded at 1/4" so I could fill up the gun from the valve up and attach a gauge as I plug the barrelport.
That way I can get a good indication.
Not sure if the strikerpin O-ring seals 100% under constant pressure though.
This too can be plugged but that would require me to take the valve apart again.

I'll see.
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: POLAND_SPUD » Fri Sep 02, 2011 3:11 pm

a pressure gauge is a must!!
first of all, it tells you what pressure you achieved... obviously MOAR = MOAR power and we want MOAR of it

and secondly you can check if there are any leaks...
two birds with one stone


not to mention that it's a must for future tweaking of spring strenght, hammer weight etc.
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Unread postAuthor: Brian the brain » Fri Sep 02, 2011 3:44 pm

Indeed.
I just tried it.
Plugged the barrel and put a checkvalve and gauge on.
Filled up the dead space with oil.
40 pumps gets me about 16 bar. :cry:

Also I found out that one weld is leaking, but that was on on the menu anyway even if it were just for looks!
The leak might influence the reading a bit, but not that much.

A bit disapointed to see such a low pressure reading...but on the other hand...that means performance will go up massively when I pump it to 40 bar or higher...wich is promising concidering the results I have gotten so far.

I now know that roughly each 5 pumps give me 2 bar..
So 100 pumps seems like a good number.
That will require a longer lever I think...

It is tempting to fill up the reservoir with a spacer to get the number of pumps down...But that won't help performance....
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Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: Labtecpower » Fri Sep 02, 2011 3:49 pm

Maybe it would be nice to use a pressure gauge like this

It looks very sleek, and is easier to fit in a design than round pressure gauges..
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Unread postAuthor: Brian the brain » Fri Sep 02, 2011 3:55 pm

Hmm

This test was great but I'm not putting a gauge on the gun.
It doesn't fit into my design.It would have to be placed at the bottom and threading into small diameter pipe wall at 90 degrees is hard to do right, and it is prone to leak.
Neither am I going to weld on a nipple.I don't want welds in the area that contains the pressure.

Counting the number of pumps is good enough.

(edit) Oops..I guess the leak makes quite a difference..
I get the same reading at 60 pumps....with a louder hiss.
So the pump is definately reaching higher pressures...

Got me some welding to do!
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: Brian the brain » Sat Sep 03, 2011 2:19 pm

more progress.
Made a breechplug thingy like on a crossman pistol..

Fixed the weld, now it's a solid chunk of metal..
I took a picture of the pressure test set up.
Still...40 pumps I get 16 bar...hmm..

Oh well...100 pumps it is.
It's still selfcontained.

I am seriously thinking about building a CO2 12 gram version pistol using the same valve...I imagine a revolving cilinder around the pressuretube... :D
That would have some amazing power!

I found out now that the welds are no longer leaky...that when I depress the valve it stays open!
When I pull it closed it slides back in...
When I release the pressure, it closes!
Yeah!!
This means it stays open until the barrel is empty!!
Maximum power and minimum waste!!

Okay...In theory...but still cool..
On with some pics:
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Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: wyz2285 » Sun Sep 04, 2011 6:40 am

nice job, I´m building one simular but without a pump :roll: can´t make one good enough :oops: nice valve! :thumbright: I really need to make one :twisted:
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Unread postAuthor: Brian the brain » Sun Sep 04, 2011 7:27 am

And pretty poweful at only 40 pumps too:

[youtube]http://www.youtube.com/watch?v=n0AdCxVQKGw[/youtube]
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Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: Labtecpower » Sun Sep 04, 2011 7:43 am

Mooi man!

Ben even bij Brezan geweest, daar hebben ze alle O-ringen die ik nodig heb. Bedankt voor de tip!

Misschien heb ik rond de winter ook wel iets voor de competitie.
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Unread postAuthor: POLAND_SPUD » Sun Sep 04, 2011 9:32 am

heh nice
but it requires way too many pumps... I think you need a longer stroke pump and an longer lever
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Unread postAuthor: Brian the brain » Sun Sep 04, 2011 11:40 am

After the first shot it requires less.
Like 10 or so.
The idea is to have big reservoir performance...

But indeed, longer stroke and longer lever would be better.
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: Gippeto » Sun Sep 04, 2011 12:17 pm

Looks like good performance. 8)

Might want to reconsider the gauge...or use a chrony to figure the number of pumps needed to bring it back up.

That's bloody WELL DONE! :D (Not meaning near finished...although that's sort of true too. :wink: )
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