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    Pump Action Pencil Launcher

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    JoergS
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    Pump Action Pencil Launcher

    Post by JoergS on Tue Mar 06, 2012 9:42 am

    A pencil can be very dangerous - when The Slingshot Channel builds a weapon around it!

    The "Nerd Revenge 2000" is a homemade pump action slingshot crossbow that can fire 10 razor sharp pencil in under five seconds. The "arrows" travel at an impressive 100 miles per hour, fast enough to go through an apple!

    The compact weapon (24" = 60cm) can also fire a "devilled" version if a pencil, with an achery field tip glued in. Then the once so harmless pencil is turned into a deadly projectile!

    The design was inspired by the Chinese Repeating Crossbow, but the awkward repeating action has been replaced by the far better "pump gun" method. The rubber bands are pre-tensed to 300% and stretched to 500% when you shoot. This means you get good power at a relatively compact size. My experiments with super slomos and the thermal test series laid the ground for this new concept.

    This is probably the most fun slingshot I ever shot!


    JoergS
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    Re: Pump Action Pencil Launcher

    Post by JoergS on Tue Mar 06, 2012 1:17 pm

    I just had to do it. Against all odds.

    I doubled up the rubber.

    Now we are talking!

    The stronger bandset pushes the weapon into the realm of deadly weapons. The pencils now go through a rubber door mat, which withstands the 20 mm steel ball hits from my strongest slingshots!

    As a matter of coincidence, some better quality pencils arrived (Faber-Castell HB, 1,18 Euros for twelve pieces including tax). Much more solid. Just in time.

    But in order to push the envelope even farther I took a damaged carbon fibre arrow shaft, sawed it into five pieces and glued tip holders in. Then I screwed the field tips in. The arrows now weigh 9,6 gramms (154 gr).

    The impact is absolutely astounding. They go into a massive wooden plank and I need tools to get them out again. They even pierced through a PET water bottle and still stuck in the plank. Distance 8 meters, the flight is absolutely stable.

    I reinforced the string catchers (glued in a steel nail in fact), so the weapon withstands the much harder impact of the 300% pretensed bands (3,5 cm x 2,5 cm x 11 cm relaxed length).







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    stoneagebowyer
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    Re: Pump Action Pencil Launcher

    Post by stoneagebowyer on Tue Mar 06, 2012 2:15 pm

    Joerg! This is one badass little weapon, and very deadly. I am so impressed. I'd like to build one myself. Could you post a photo or two of the rubber band catches on your slide, so I am sure I understand what is going on.

    I was laughing the whole time watching this video. You make awesome weapons, every time.

    Dane
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    Basilisk120
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    Re: Pump Action Pencil Launcher

    Post by Basilisk120 on Tue Mar 06, 2012 9:16 pm

    Wow! once again Joerg you bring it. Very Happy That is one sweet looking crossbow/slingshot and a shooter too. Shocked



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    Archer46176
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    Re: Pump Action Pencil Launcher

    Post by Archer46176 on Wed Mar 07, 2012 9:55 am

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    Last edited by Archer46176 on Wed Mar 07, 2012 2:41 pm; edited 1 time in total
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    mac
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    Re: Pump Action Pencil Launcher

    Post by mac on Wed Mar 07, 2012 2:04 pm

    Joerg,

    It is always a pleasure to see what you are up to!

    Mac
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    Ivo
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    Re: Pump Action Pencil Launcher

    Post by Ivo on Wed Mar 07, 2012 2:29 pm

    I don't even know if we can call this one a *plinker* Smile ...cool stuff Joerg.

    Any chance of plans for this?

    I think the greatest honor we can give Joerg is by actually *reverse engineering* his creation into principals of operation and reconstructing it into a re-sizable model. After all we're a Guild guys, and have the knowledge. Wink

    Give it a go guys, I think that way Joerg will enjoy our company a little more if we don't simply copy his build, but interpret it in our own unique ways to build a personalized version and I'm sure that he'll have more fun answering the more technical questions we encounter as we break it down.

    Give it a go guys. Very Happy

    Again, good seeing you stop by Joerg. If you can post a few shots of this slingshot from different angles, I think it'll help us a little more in getting the details down for reconstruction.

    Thanks,

    Ivo




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    JoergS
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    Re: Pump Action Pencil Launcher

    Post by JoergS on Thu Mar 08, 2012 4:52 am

    Ivo, I will upload some pictures for sure. I am lousy with blueprints and would LOVE some help!

    I am now working on a more serious model. It will shoot 40cm (16") long aluminum tubes, 15mm (.59") outer diameter, with a steel "tip" made from 12 mm (.47") stainless rods.

    In order to master the massive draw force needed for this, the butt will rest on the middle of my chest, with hooks that go over my shoulders and a belt that secures everything. Then, the slide is pulled back with both hands, in a "rowing" fashion. This will allow up to 250 lbs of draw weight (I am a strong guy), which should be enough to shoot these deadly projectiles at maybe 170 fps or so.

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