Pneumatic Pen Gun is Fit for James Bond

The James Bond franchise is well-known for many things, but perhaps most important to us hackers are the gadgets. Bond always had an awesome gadget that somehow was exactly the thing he needed to get out of a jam. [hw97karbine’s] latest project would fit right into an old Bond flick. He’s managed to build a single-shot pellet gun that looks like a pen.

[hw97karbine] started out by cutting the body from a tube of carbon fiber. He used a hacksaw to do the cutting, and then cleaned up the edges on a lathe. A barrel was cut from a piece of brass tubing with a smaller diameter. These two tubes will eventually sit one inside of the other. A custom front end cap was machined from brass. One end is ribbed and glued into the carbon fiber tube. The barrel is also glued to this end of the front cap, though it’s glued to the inside of the cap. The other end of the cap has 1/8″ BSP threads cut into it in order to allow for attachments.

A rear end cap is machined from Delrin. This piece also has a Delrin piston placed inside. The piston has a small piece of rubber used as a gasket. This piston valve is what allows the gun to operate. The rear cap gets glued into place and attached to a Schrader valve, removed from an automotive tire valve stem.

To pressurize the system, a bicycle pump is attached to the Schrader valve. This pushes the piston up against the barrel, preventing any of the air from escaping. The piston doesn’t make a perfect seal, so air leaks around it and pressurizes the carbon fiber tube. The Schrader valve prevents the air from leaking out of the pen body. A special machined button was threaded onto the Schrader valve. When the button is pressed, the air escapes; the sudden pressure imbalance causes the piston to shoot backwards, opening up a path for the air to escape through the barrel. This escaping air launches the projectile. The whole process is explained better with an animation.

Now, the question left in our mind: is this the same pressure imbalance concept that was used in that vacuum pressure bazooka we saw a couple years back?

[Thanks ch00f]

52 thoughts on “Pneumatic Pen Gun is Fit for James Bond

    1. Reminded me of the same thing, only a lot smaller. The build quality is absolutely amazing, but it doesn’t have BB’s full of deadly ricin. Without the ricin the only thing this gun is going to kill is empty soda cans.

    2. Damn, beat me too it! And, Spaz, don’t think this little beauty is nothing without ricin, put it up against someone’s temple and pull the trigger and you’ll ruin they’re whole day.

  1. Do you think it is advisable to share such “hacks” on hackaday? I am an enthusiastic reader of your blog, however, I would like not to see such things here. Don’t know what the others are thinking…

    1. I think posting this hack here is fine. I can only assume (and hope?) that the general populous has enough wisdom to know “how to use” this hack without making others feel nervous. Just my two cents.

      1. I agree. I don’t have the same faith in the general populace, but this site is dedicated to us, sharing information on how we solve problems. The methods used here could be applied to (in an extreme case) a needle-free pneumatic injector for vaccines.

    2. IDK if this is trolling or legit. But, if you didn’t like it why did click on it and support ad revenue for the page, as well as a comment string? Must we all be deprived of information because it offends your delicate sensibilities?

        1. What else in the article could be offensive that can’t be deduced from the headline? I think its fair to say that the commenter is upset at the word gun, or that this propels a projectile not that the builder used a schrader valve instead of presta. Its a public space, dedicated to people doing all sorts of things. Next manufactures might complain a mod violates their user agreement and we must not share these things.

    3. Jens, I would like to not see posts like yours here. I find them offensive. If you wish to be a Luddite, please do it elsewhere.
      I like this hack, please post more like it.

      1. First of all: It was my opinion, so do what you want with it…

        What makes me feel uncomfortabel about this “hack” is its explicit use as a weapon. I don’t like the idea of sharing instructions on how to built things like that. However, as I can extract from all the other posts, I might be too sensitive for this…

        1. it’s an interesting device and most of us wouldn’t consider it a weapon. Its a weak bb gun at most, and while it can be dangerous (wear your safety glasses) it’s very unlikely to harm anyone.

          1. Yes, I see your point. The problem for me is that my favorit blog publishes stuff like this. As I am a pacifist the true reason for my initial post is cognitive dissonance…

          2. You could do more damage with a dart and a straw…
            I’ve seen 3D printed guns and knives, as well as all sorts of electronic projects that boarder on illegal.
            Almost anything put up here can be used for ‘evil’, simply not sharing or not working on something that can be used for evil would result in us being in the stone age with square wheels.

        2. It’s an excellent example of metal craftsmanship on a small scale. If someone has the technical knowledge to reproduce it, they hopefully have the intellect not to use it senselessly.

          I’d worry more about the dimwitts running around with readily purchasable portable 1W lasers more than a pen-gun.

    4. Why not? This proves the pen is mightier than the sword! ;)

      Inventing, making and tinkering is what you can Do – not what you (mis-)use it for. I for one applaud engineering like this and it certainly has its place here! If you find a pellet-shooting pen offensive then perhaps this is not the right forum for you…

    5. I love these hacks and want more of them. If a pen that shoots a plastic pellet upsets you, you may want to avoid most all hacks sites and even Make magazine as they have covered this stuff.

    6. They don’t show you how to build something more powerful, just something that can sting. There are builds on lasers that do more damage than this. If someone scales this up, that’s on them. Hackaday probably wouldn’t publish an article on a device that was designed to kill, including build instructions. Use it on bugs, pop balloons, or whatever small object you desire. It isn’t going to hurt even a small animal.

    7. [Jens] we understand you have the no-contact com jacket and are very triggered they don’t have the eyeglasses variant for things you see. I fully encourage your to form a tumblr kickstarter campaign to protect your freedoms for the kids because otherwise fear uncertainty and doubt will win.

      “advisable to share such “hacks” on hackaday?”

      Yes/ Knowledge in any form is a TOOL, whether you use a ROCK to crack open a coconut, split tree bark to eat a grub, mill flour OR any other purpose is BASED on the IMAGINATION of the individual USING that tool.

      What sick junk do you have in your head [Jens]

  2. .25g @ 475fps = 2.61j

    Most airsoft games allow weapons up to 1.5j and many allow up to 1.85j.

    1j at point blank range on bare skin won’t puncture the skin. 1.5j at point blank on clothes hurts and leaves a mark.

    Dial the FPS down on this a little and it would be allowed at nearly all airsoft fields.

    I wouldn’t have a problem getting shot by it.

    1. This is not supposed to be airsoft, this is a pellet. It shoots the same ammunition used by air rifles – designed to kill small rodents and used in competitive target shooting.

      1. The video gives a chrono test with weights and speeds that are used in airsoft, and the bore is the same as airsoft. The photo shows a pellet, but it is capable of being use with 6mm airsoft BBs.

    1. So did the heroes with guns.

      You’re four times more likely to get shot yourself trying to defend yourself with a gun, because the one who points first usually manages to shoot first and you just gave them a reason.

      1. In the UK, legal gun owners are less likely to be involved in violent crimes of any kind – not just gun crimes, but knifes, domestic violence, etc.
        however, that probably more to do with the demographic of legal gun owners in the UK.

    1. Hey, great work!
      Not wanting to criticise at all, but how safe is it? I assume you did some calculations for the strength of the tubing against the pressure, but what about how the end caps are fitted, or what happens when it takes a knock or gets dropped?
      Also, how long does it retain its pressure?

      1. Thanks!

        Regarding safety, the pressure vessel is very strong, I’ve hydro tested it to 850 psi with no failure, the fail pressure of the tubing is at least 3 times the working pressure, and even if it does fail the amount of air inside the chamber is not significant. It will keep pressure overnight without loss, just like most pneumatic air guns.

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