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Heres a little video of my first piston gun

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Heres a little video of my first piston gun

Unread postAuthor: watto » Thu Nov 29, 2007 2:45 am

What do yous reckon

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[youtube]http://www.youtube.com/watch?v=8QjslEtFxIc [/youtube]
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Unread postAuthor: Killjoy » Thu Nov 29, 2007 3:43 am

That was pretty impressive...and that was a lot of newspaper to be penetrated. Pretty cool.
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Unread postAuthor: watto » Thu Nov 29, 2007 4:36 am

yeh I didnt think It would make it all the way through, Its power definately surprised me.
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Unread postAuthor: mega_swordman » Thu Nov 29, 2007 5:07 am

Ah! you might want to invest in a partner to conrtol the camera. Too much movement. Otherwise it looks good.
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Unread postAuthor: watto » Thu Nov 29, 2007 5:11 am

Yeh pretty hopeless I know, If I was smart I would have also turned on the light....(FARK!) :roll: :roll: :roll:
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Unread postAuthor: jrrdw » Thu Nov 29, 2007 6:05 am

Didn't sound like alot of pressure behind that shot. Any idea how much it was? At that range 18"s or so, i would think the marble would go through all the paper and box into what was behind it. Nice cannon, I like it!
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Unread postAuthor: watto » Thu Nov 29, 2007 6:22 am

jrrdw wrote:Didn't sound like alot of pressure behind that shot. Any idea how much it was? At that range 18"s or so, i would think the marble would go through all the paper and box into what was behind it. Nice cannon, I like it!


The shot was at 90-100PSI I think, the camera must not have a good microphone because the shot was deafening in that small room. The ammo was a round lead fishing sinker not a marble.
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Last edited by watto on Thu Nov 29, 2007 8:56 am, edited 1 time in total.
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Unread postAuthor: jrrdw » Thu Nov 29, 2007 6:42 am

I didn't notice any wadding. How good of a fit is the sinker? Try some wadding next time, i think it will improve power no dought. I sagest a stronger target or shoot outside to keep from tearing up anything important! How much did the sinker weight?
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Unread postAuthor: watto » Thu Nov 29, 2007 7:35 am

jrrdw wrote:I didn't notice any wadding. How good of a fit is the sinker? Try some wadding next time, i think it will improve power no dought. I sagest a stronger target or shoot outside to keep from tearing up anything important! How much did the sinker weight?


If you freeze the video just when I look at the hole for the first time, you can see the tightly packed clingwrap I used as wadding wedged in the hole, but I pulled it out with my other hand off camera.

The reason I dont shoot outside at my own house anymore is because I always end up putting holes in my fence or getting some neighbour complaining because they had a potato land in they're pool :lol:

I imagine the sinker would have weighed around 50g.
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Unread postAuthor: psycix » Thu Nov 29, 2007 7:54 am

Nice cannon.
I am planning to build something similar like that soon.

How long are your barrel and chamber?
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Unread postAuthor: watto » Thu Nov 29, 2007 8:55 am

chamber is 50mmx45cm, barrel is 15mmx100cm. If the boot of my car was bigger I would have made the barrel heaps longer. When you buy 15mm pipe check that it doesnt already have a bow in it, if its bent it can it makes things difficult.
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Unread postAuthor: jackssmirkingrevenge » Thu Nov 29, 2007 8:57 am

If the boot of my car was bigger I would have made the barrel heaps longer.


surely there's some fittling that will allow you to fit a removable extension?
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Unread postAuthor: watto » Thu Nov 29, 2007 9:14 am

Well, I suppose I could get a thread and screw type arrangement, but the threads I've seen around my way tend to reduce the size of the pipe. Even if it didn't reduce the pipe I imagine there would be a quite significant a bump in the barrel from the join. Another possible problem with that is that the rounds I let off, tend to be not on my own property, or anywhere where I should be discharging a firearm, therefor I have to make a speedy exit immediately after the loud shot, so unscrewing a barrel may slow down my retreat.

JSR what do you think the power gain would be from doubling the barrel length (the current ratio is around 5:1) Do you think the 'bump' in the barrel due to the join would create too much resistance?
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Unread postAuthor: jackssmirkingrevenge » Thu Nov 29, 2007 9:57 am

I have to make a speedy exit immediately after the loud shot, so unscrewing a barrel may slow down my retreat.


... but a longer barrel will give you quieter shot ;)

what do you think the power gain would be from doubling the barrel length


The gain would be significant, I don't have GGDT handy but as a guestimate I'd say at least 15-25% increase in velocity.

Do you think the 'bump' in the barrel due to the join would create too much resistance?


It depends what you're firing - for spherical projectiles it wouldn't really make a difference as long as the two sections are in line.
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Unread postAuthor: f.c » Thu Nov 29, 2007 6:03 pm

i like the gun. are you an Australian as you seem to measure you're pipe in mm. also what is that song playing in the background it seems very familiar.
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