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mini pneumatic ballistic knife

Built a miniature 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: Zeus » Sun Sep 04, 2011 6:00 pm

Thanks for the advice. I'll let the thread return to it's original topic
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/sarcasm, /hyperbole
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Unread postAuthor: Coablt96 » Mon Sep 05, 2011 1:55 pm

hey if any one can tell me how does this release mech. work i don't seem to get how it works on the pneumatic ballistic knife :?:
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Unread postAuthor: jackssmirkingrevenge » Mon Sep 05, 2011 2:25 pm

It works just like quick connect fittings, when the collar is pushed forward, the bearings are free to move and release the blade.

Image

Here's an example of an actual quick connect fitting being used as a release valve:

Image

Another possibly way of putting it togther, in this case the air propells a piston as opposed to acting directly on the knife itself, with the added benefit of the gasses being retained thus greatly reducing firing noise.

Image
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Unread postAuthor: urgle the danish cow » Wed Sep 21, 2011 4:46 pm

i know this is an old thread but jack. eat your heart out
built this some time ago and finally got to finish blade

http://www.youtube.com/watch?v=4BeQBjV-P-A [/url]
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Unread postAuthor: PVC Arsenal 17 » Wed Sep 21, 2011 6:36 pm

jackssmirkingrevenge wrote:Another possibly way of putting it togther, in this case the air propells a piston as opposed to acting directly on the knife itself, with the added benefit of the gasses being retained thus greatly reducing firing noise.

Image


I wonder if you could adapt a water hammer arrester to drive a blade in the same manner.

Image

I have the same arrester as that one and what I noticed was that it required a lot of force just to move the internal piston about an inch. I'm not sure if it could give the blade adequate acceleration. I'd also be concerned about the pushrod damaging the [plastic] internal piston due to the force. Only one way to find out...
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Unread postAuthor: jackssmirkingrevenge » Wed Sep 21, 2011 11:07 pm

PVC Arsenal 17 wrote:I wonder if you could adapt a water hammer arrester to drive a blade in the same manner.


Interesting thought, but you're still limited to what you can recock inline (unless you use a lever, vice or hydraulic press etc.) which is similar to the spring powered ballistic knives - as opposed to pneumatics where you add the pressure incrementally with a pump and can achieve a lot more compression.

I actually bought a couple of quick-connects with the intention of building the last design posted but now I'm not so sure that a how-to of a quiet ballistic knife that can be built by "anyone" is such a good idea.

i know this is an old thread but jack. eat your heart out
builtthis some time ago and finally got to finish blade


Looks good :) seems a bit on the heavy side though. How easy is it to fire, I imagine there's a lot of friction on that single contact point.
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Unread postAuthor: PVC Arsenal 17 » Thu Sep 22, 2011 12:18 am

jackssmirkingrevenge wrote:but now I'm not so sure that a how-to of a quiet ballistic knife that can be built by "anyone" is such a good idea.


Make one but never tell anyone 8)

I'm sure a lot of us here follow that rule given some of the crazy laws these days...
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Unread postAuthor: jackssmirkingrevenge » Thu Sep 22, 2011 1:08 am

PVC Arsenal 17 wrote:Make one but never tell anyone 8)


... but in that case, what's the use of using standard parts when I have a lathe and mill?

I'm sure a lot of us here follow that rule given some of the crazy laws these days...


Certainly much of the stuff I've done recently I haven't published. I was talking to a technician doing some maintenance on one of our instruments and casually mentioned I had invested in some machine tools and his immediate reply was "What do you want them for? Weapons?" - I was a bit taken aback, "Well... uh, steam engines?". "Sure ;)"

:roll:
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Unread postAuthor: urgle the danish cow » Thu Sep 22, 2011 4:00 pm

Looks good :) seems a bit on the heavy side though. How easy is it to fire, I imagine there's a lot of friction on that single contact point.[/quote]

its not to heavy bc the rear is aluminiom and the steel blade keeps it front heavy and going straight. also it has a lot of air volume. it used to be hard to shoot but i filed a 45 degree angle where the 90 degree angle was at the end of the notch to help with that
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Unread postAuthor: maklaw » Thu Oct 06, 2011 6:26 pm

very good, simple and effective
Un poco de color y de llavero
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Unread postAuthor: jackssmirkingrevenge » Thu Oct 06, 2011 11:13 pm

Gracias, tengo un otro planeado, utilizando esta hoja hecha por jakethebeast:

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Unread postAuthor: maklaw » Fri Oct 07, 2011 5:21 am

Eso es increíble, tiene muy buen aspecto
Ya tengo ganas de verlo acabado
Me preocuparía mantenerse recto a una distancia de unos 6metros ?!
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Unread postAuthor: jackssmirkingrevenge » Fri Oct 07, 2011 6:28 am

maklaw wrote:Me preocuparía mantenerse recto a una distancia de unos 6metros ?!


Hay que ver la relacion entre centro de presion y centro de gravedad, el primero tiene que ser detras el segundo:

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Unread postAuthor: jakethebeast » Fri Oct 07, 2011 2:38 pm

JSR, you posted the blade i made for you, it would be kind to tell me what ya guys were talking about it :D
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Unread postAuthor: al-xg » Fri Oct 07, 2011 2:58 pm

"Nice, you should make it pretty."
"!I have other plans: Look shiny!"
"?but Jack will it fly straight?"
"Have a look at this wonderful diagram illustrating the CP-CG relationship with stability."

Context translator :)
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