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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: POLAND_SPUD » Wed Jun 24, 2009 11:31 am

@daccel
well the idea was to attach a thin wire to prevent ammo from falling down the port...

@turbo
I had a lot of problems with flow restrictions.. this seems to be the easiest way to convert what I have now and keep all the things I want to have on this gun (that is - a large capacity hopper)...
on that vid quite a lot of power is wasted by flow restrictions so it isn't as good as it could be

having the entire barrel move

moving the whole barrel seems a little tricky.. I know it can be done but I suppose it will work better on smaller calibers... you know the mass of the barrel being thrusted by the air cylinder forward and backward all the time...

hmmm just attach a dildo at the end of the muzzle and you have a perfect present for JSR
:D


anyway I think that the biggest issure here is sealing the bolt and making sure that the ports won't dammage o-rings/seals
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Unread postAuthor: THUNDERLORD » Wed Jun 24, 2009 1:42 pm

POLAND_SPUD wrote:
having the entire barrel move

moving the whole barrel seems a little tricky.. I know it can be done but I suppose it will work better on smaller calibers... you know the mass of the barrel being thrusted by the air cylinder forward and backward all the time...

hmmm just attach a d*ldo at the end of the muzzle and you have a perfect present for JSR
:D


anyway I think that the biggest issure here is sealing the bolt and making sure that the ports won't dammage o-rings/seals


Yeah, I've thought of sleeves on the mag, all kinds of stuff.
For less restriction, stronger steel is useful.
(It's all that weak point between magazine, bolt and barrel)
The part about the "present for JSR" ...
Reminded me, I got carried away looking at nasty pic stuff ,(which I almost never do),(reason I'll win contest(?)... but I could link to some machinery I'm trying to forget right now... :lol: (Think I'll get one of those kiddy filters for wifey's home computer just incase) :lol: :evil: :evil: :shock: :oops: 8)
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Unread postAuthor: Carlman » Wed Jun 24, 2009 1:50 pm

I know what ur on about thunderlord with the machinary, do not link to them lol
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Unread postAuthor: Technician1002 » Wed Jun 24, 2009 1:59 pm

THUNDERLORD wrote:Reminded me, I got carried away looking at nasty pic stuff ,(which I almost never do),(reason I'll win contest(?)... but I could link to some machinery I'm trying to forget right now... :lol: (Think I'll get one of those kiddy filters for wifey's home computer just incase) :lol: :evil: :evil: :shock: :oops: 8)


I know, offtopic, but changing the DNS settings to one of the free filtered DNS may help. Just find one that doesn't filter spudfiles. :D

When we had kids, I used scrubit.
http://www.scrubit.com/

What's nice is sites hosting malware are quickly filtered, so email with links to malware don't work.

Just use these DNS settings in your network settings instead of the ISP provided ones.
67.138.54.100 207.225.209.66 It's that simple.
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Unread postAuthor: POLAND_SPUD » Wed Jun 24, 2009 2:04 pm

maybe I shouldn't admit it.. but I know what he meant :twisted:
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Unread postAuthor: THUNDERLORD » Wed Jun 24, 2009 4:13 pm

POLAND_SPUD wrote:maybe I shouldn't admit it.. but I know what he meant :twisted:


Geez, I was watching a show where they said in the future ALL homes will have robot assistants... .... .... I might smash mine if it gets to that :twisted: :lol:
Hope you post the "MKII" soon!!!

@Tech, thanks for the info!
When I was single, it was a different world. I never expected a place with my own family and people I could trust again. I made a joke, but seriously, I don't want that type of mixed up crap around whether it's accidental or not. I'll try that filter soon. 8)
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Unread postAuthor: Technician1002 » Wed Jun 24, 2009 4:24 pm

THUNDERLORD wrote:
POLAND_SPUD wrote:maybe I shouldn't admit it.. but I know what he meant :twisted:


Geez, I was watching a show where they said in the future ALL homes will have robot assistants... .... .... I might smash mine if it gets to that :twisted: :lol:
Hope you post the "MKII" soon!!!

@Tech, thanks for the info!
When I was single, it was a different world. I never expected a place with my own family and people I could trust again. I made a joke, but seriously, I don't want that type of mixed up crap around whether it's accidental or not. I'll try that filter soon. 8)


Just a word of caution. Spammers hate it and I found it was often DDOS attacked and could be offline for extended periods. :( Having the web "page not found" sucks. On a bright note, if you learn to edit your hosts files, many websites can be DNS hosted locally so if DNS filters, blocks, or is down, the locally entries still work. For example, add spudfiles to the hosts files and it then works even with filtered DNS.

For example spudfiles DNS address is 208.116.36.56. Entering http://www.spudfiles.com with the address of 208.116.36.56 will bring up spudfiles even when DNS is filtered, down, or attacked. Google hosts file to see more. I put in my most frequent websites, bank site, and other stuff I needed immune from spoofing, etc.

Edit, This may not work for some sites that use virtual machines, proxy, or gateway. Spudfiles appears to be this way. I just get the hosting webserver instead of the page when using just the IP address returned by ping. Spudfiles appears to be hosted by a company called Cirtex-Corp.

http://www.cirtex.com/
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Unread postAuthor: POLAND_SPUD » Fri Jul 10, 2009 7:41 pm

again I have serious troubles with this project...
right now I've finished this feeding mechanism -> http://www.spudfiles.com/forums/files/bez9_156.png
however, air leaks through the ammo port when I shoot...

the 'bolt' is just a 16mm rubber washer sandwitched between two steel washers, two nuts are used to hold it in place and to squeeze the rubber washer...

everything seems to seal pretty good - I tried blowning air down the barrel and it doesn't leak but when I fire the gun it does

would an o-ring work better here??
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Last edited by POLAND_SPUD on Sun Jul 12, 2009 4:34 am, edited 1 time in total.
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Unread postAuthor: jackssmirkingrevenge » Sun Jul 12, 2009 4:27 am

Squeeze a bit harder?
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Unread postAuthor: MRR » Sun Jul 12, 2009 5:01 am

Is it possible that the seal leans a little bit? Try to make a washer - rubber - washer - rubber - washer combination. This way it always has 90°.
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Unread postAuthor: POLAND_SPUD » Sun Jul 12, 2009 2:21 pm

I've just did some tests... well the problem is that in this design there is quite a lot of force pushing the 'bolt' out upon firing... yeah I know it's obvious but somehow I've missed that :oops:

I did squeezed it a little bit more and it helped.. but the more I squeeze it the more firction there is... basically up to a point where I have to ditch the spring and switch to a full double acting cylinder (which isn't complicated at all but I don't have a 1/2" to 1/4" female adapter to connect the chamber with the air cylinder.... but I think it won't be difficult to improvise a compression fitting to do the trick)


the good news is that performance is great.. I couldn't notice any difference between this and a single shot version of the same gun... apparently, getting rid of that flow restricting flow-through bolt was the right choice...
the gun is still in prototype phase... I need at least one or two days to make it look good enough to show it

oh, BTW I bought a dremel a couple of weeks ago.. it's a great tool, especially if you are into small bore guns as it makes working with small parts much easier

EDIT
I switched it to a double acting cylinder and it finally works the way it should (meaning no leaks)... now I just have to redo my chamber so that I could use it as a stock
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Unread postAuthor: POLAND_SPUD » Sat Aug 08, 2009 12:09 pm

update
I know I promised to update this long long time ago but I had other things to do :cry:

the mechanism stays the same but I switched from a flow through bolt to a solid bolt... there is a pic of it created in sketchup in one of my posts here...

ammo is loaded on one side of the T and is pushed by the bolt through it to the other side...
there are two ports cut in the barrel with a dremel: one for ammo and the one through which air flows into the barrel (directly in the middle of the T above the barrel)

here a vid showing the gun and how it operates...plus, one of those 'oops!!' moments (I accidentally hit some thing I shouldn't) :wink:
[youtube]http://www.youtube.com/watch?v=jxfTeLxvzWo[/youtube]

there are virtually no flow restrictions at least I couldn't notice any difference between this and a single shot version of the same rifle (which was basically a muzzle loading single shot marble gun)

mag capacity is about 7 rounds in these vids but I can use even a 1 litre cola bottle as a hopper...
pressure used in the vids - roughly 150 psi
distance to the target - about 15 meters
notice the 'bamboo shot' (literally) ;-) at :38... it nicely shattered a bamboo stick


[youtube]http://www.youtube.com/watch?v=jMXqICsqwQw[/youtube]

thanks to charigun (an external ballistic program for airguns) I know that marbles lose roughly 50% of their muzzle energy at 30 - 35 meters... so I am thinking again about switching to a smaller caliber (0.965mm ball bearings) and switching to 88g co2 cartrides...

I see certain advantages to it apart form better external ballistics of ammo, mainly:
-lower air consumpion
-possbility of adding an inbuilt full barrel lenght coax silencer
-lower mass

with if you have other ideas as to which caliber I should choose feel free to post it

I run out of ammo today... more vids soon
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Last edited by POLAND_SPUD on Sat Aug 08, 2009 12:53 pm, edited 2 times in total.
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Unread postAuthor: jackssmirkingrevenge » Sat Aug 08, 2009 12:12 pm

Very nice :) but you have to explain that final "oops!" :D What did you hit?
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Unread postAuthor: POLAND_SPUD » Sat Aug 08, 2009 12:36 pm

it wasn't as bad as it could be...it penetrated both sides of one of the garden crates that you can see there and then deflected.. the next 'oops' moment came 3 or so seconds later when I heard that it had fallen on the roof of the greenhouse :D (but no damage was done)

as you can see the greenhouse is rather close to my shooting range so..uhmm.. how should I put it...
well I suppose that after all these years I am as good as a professional glazier
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Unread postAuthor: jackssmirkingrevenge » Sat Aug 08, 2009 12:44 pm

What did we say about backstops ;)

Looking forward to the damage vid, how fast can it fire in terms of rate? As fast as you can pull the trigger or is there a minimum delay?

Accuracy seems to remain all over the place, I can see why you didn't move the camera any closer :P what about damage, what was the target (metal sheet?) and how come the first shot seems to penetrate and the others don't?

Power seems fairly low for a marble gun at 150 psi. I would put it down to lack of flow and too much dead space, so in this case a move to a smaller calibre with denser projectiles would probably be quite an improvement.
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