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mini pneumatic ballistic knife

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mini pneumatic ballistic knife

Unread postAuthor: jackssmirkingrevenge » Sat Sep 03, 2011 8:12 am

Following a discussing in the knife thread, decided to put a little prototype together.

Here it is in action at 300 psi in real time, 420 frames per second and 1000 frames per second:

[youtube]http://www.youtube.com/watch?v=ZYGg_xT16Bo&feature=channel_video_title[/youtube]

[youtube]http://www.youtube.com/watch?v=7wn5_SsMvBA&feature=channel_video_title[/youtube]

[youtube]http://www.youtube.com/watch?v=IhoWMLueuyM&feature=channel_video_title[/youtube]

The knife blade is from a cheap little made-in-Taiwan knife, the rest of it is in Delrin. Chamber is an aluminium tube with a Delrin collar and 3mm steel bearings as a detent.

Some photos:
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mbkknifechamber.JPG
knife and chamber
mbkfiringsequence.PNG
Firing sequence and internal details
mbkdetentclosed.JPG
close up of the detent in the closed position
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Unread postAuthor: al-xg » Sat Sep 03, 2011 8:18 am

I'd be interested to know at what pressure the ring fails.

Interestingly this is one occasion where slow motion does not make it look cooler :D
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Unread postAuthor: jackssmirkingrevenge » Sat Sep 03, 2011 8:22 am

al-xg wrote:I'd be interested to know at what pressure the ring fails.


I made it out of Delrin because it's so easy to work with, seems ok at 300 psi. I'll take it higher after I'm sure the epoxy is fully cured.

Interestingly this is one occasion where slow motion does not make it look cooler :D


hehe that's exactly what I was thinking :)
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Unread postAuthor: LeMaudit » Sat Sep 03, 2011 8:31 am

Great work :D
I love it!
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Unread postAuthor: Gun Freak » Sat Sep 03, 2011 8:48 am

That's so cool!! :D
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Unread postAuthor: jackssmirkingrevenge » Sat Sep 03, 2011 9:20 am

Cheers guys, this thing is really a lot of fun! Here's some more shots, with a little something the Dutch members might appreciate :)

[youtube]http://www.youtube.com/watch?v=_tV8aEMa7wY[/youtube]
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Unread postAuthor: warhead052 » Sat Sep 03, 2011 9:20 am

Nice job! Are you going to try a higher pressure when the epoxy has fully cured? If so, I may try making one of these.
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Unread postAuthor: jackssmirkingrevenge » Sat Sep 03, 2011 9:38 am

Took it to 400 psi and the shoulder on the "handle" which comes into contact with the detent deformed and released the knife. A brass collar would have been a good idea :)

One other thing worth noting, the collar is extremely difficult to push forward past 350 psi.
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Unread postAuthor: Labtecpower » Sat Sep 03, 2011 10:06 am

Heineken! because it's empty i'll take it as a compliment :D

I prefer Hertog Jan, Palm, or Grolsch however :)

If you polish the thing, and make a brass collar it will look very nice.
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Unread postAuthor: clemsonguy1125 » Sat Sep 03, 2011 10:17 am

That looks pretty cool, but in america I know spring powered ballistic knives are illegal and can carry jail time. My guess would be pneumatic ones as well. Since I have no idea what country you are in.
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Unread postAuthor: jackssmirkingrevenge » Sat Sep 03, 2011 10:51 am

Labtecpower wrote:Heineken! because it's empty i'll take it as a compliment :D


Do I sound like a guy who would shoot a full can of beer, even if was a shítty brand ;)

I prefer Hertog Jan, Palm, or Grolsch however :)


It's not the best Dutch beer but definitely the easiest to get hold of outside of Holland.

If you polish the thing, and make a brass collar it will look very nice.


Yeah, cap for the schrader, strip down and polish the blade... but you know me and aesthetics.

That looks pretty cool, but in america I know spring powered ballistic knives are illegal and can carry jail time. My guess would be pneumatic ones as well. Since I have no idea what country you are in.


Sounds a bit silly in a country where you can freely buy a semi-automatic rifle, unless they are considered to be in the same category as a suppressor - but even so, this is a horrible choice of weapon, you only get one shot and unless you have spare blades to hand, you're just left with a handle.

For scale, here it is with my 7 inch blade spec plus - if it didn't have sentimental value, I would be thinking of scaling up and launching the latter knife...
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Unread postAuthor: clemsonguy1125 » Sat Sep 03, 2011 4:56 pm

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Last edited by clemsonguy1125 on Sat Sep 03, 2011 7:34 pm, edited 1 time in total.
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Unread postAuthor: Brian the brain » Sat Sep 03, 2011 5:38 pm

A heavier knife and a longer handle would give a bigger impact....


Oh...I don't like beer...Heineken especially!
Thanks for killing the can!



I prefer Jack Daniels on one of those rare occasions....


Oh forgot to say:

This puts you up there with Chuck Norris you know..
Just the two of you!
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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: Fnord » Sat Sep 03, 2011 6:00 pm

JSR,
If you ever have money left over from lathe/mill stuff, you may want to get an entry-level table top belt sander. A knife blade that fits your purposes could easily be done in less than an hour with one. You would probably want to heat treat it... not hard but just springy enough to keep the tip from bending over. That could be done with a simple propane torch.

But overall I'd say it turned out pretty well. I don't think it's very dangerous compared to running up and stabbing someone with it, but I guess that wasn't really the purpose of the build :)

if it didn't have sentimental value


I'm guessing that means you were jabbed with it repeatedly by a deranged leather-clad Russian?
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Unread postAuthor: Goats spudz » Sat Sep 03, 2011 8:32 pm

i think my country's laws about guns and knifes are dumb they should only be enforced in london :D
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