Last year for Christmas a friend gave me an unloaded grenade as a gift.  Since getting a chance to play with it, the triggering system has fascinated me.  The system is very simple.  The pin holds the lever (or spoon) which holds back a spring loaded striker.  When the pin is pulled and the spoon released the striker swings around to the priming charge which activates the grenade’s fuse.  I have been very impressed with the amount of force supplied by the small torsional spring to the priming charge and have wondered how else this force might be applied. I decided to take on this challenge for my upcycling project.  I felt it would be appropriate to turn this Christmas gift into a common Christmas decoration, a nutcracker.

Grenade

Infographic of grenade operation [1]

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My grenade pre-modification

Traditional nut crackers, although often beautifully crafted decorative pieces, are seldom used for or even capable of cracking nuts.  Once I had decided to use my similarly decorative (non-explosive) grenade to create a nutcracker I quickly began investigating whether this could even be done effectively.  This involved buying some common nuts which require a cracker and putting the unmodified grenade to the test.

king_nutcrackers_lp

Traditional holiday nutcracker [2]

Before I get into that I’d like to take a moment to talk about the “design cycle.”  When my team drew up what we thought the design cycle is it looked a bit like a circle with a star in the middle.  If you follow the edges you can see that; although, there is an idealized cycle in the clockwise direction, in actuality you can jump from any step to any other step as necessary.  This is intended to illustrate that in the iterative process of design a full iteration is not always necessary.

design loop

Design process as drawn by my team

IMG_2775My design process followed the cycle drawn by my group fairly closely; although, it would be hard to deviate as all possible paths are covered.   What struck me as interesting about how I designed this widget was that I essentially went once around the loop for each aspect of the design. I started with the problem of using a grenade trigger mechanism to crack a nut.  I brainstormed some ideas involving modifying the striking lever to improve impact effectiveness or position.  My first prototype was to simply hold a nut in the way of the lever.  I tested this on pecans, peanuts, and pistachios.  This was undoubtedly a sample of convenience as it is what I found at my usual grocery store.  The cracker was very effective against well lined up peanuts and pistachios.  Upon considering the fact that both of these nuts are easily opened by hand I decided to focus further testing on the pecan which is usually not easily opened.  This resulted in simply punching holes in the shell but, with two strikes the nuts could usually be opened easily by hand.  Satisfied with this result (considering the ridiculousness of my endeavor) I began to loop around a new problem.

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Bottom side of striker showing the protrusion responsible for the holes

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Test rig: my hand

The next issue was how to hold the nut in place without awkwardly contorting my hand as I had in the initial testing.  At this point I had removed the spoon from the design entirely.  After a handful of failed ideas including not holding the nut (which basically created a pecan firing device) and using rubber bands, I remembered the spoon.  Holding it on the opposite side of the grenade head from its usual position allows it to create downward force on the nut while not interfering with the striking lever.  I attached a small hinge to both the body of the grenade and the spoon using JB Weld.  Adding the hinge allowed for the spoon to swing and made it easy to both use and understand how to use.

Welded Grenade

Images of the grenade with the spoon JB Welded on

At this point I tested the mechanism once again and the performance actually improved.  Rather than punching a small hole as it had done initially the impact was causing cracks in several directions very consistently.  This weakened the shell enough to be broken by simply squeezing between a finger and thumb.  This resulted in very easy to open pecans without crushing the meat inside.

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Loaded and ready to crack

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Nut clamped in by the spoon

Happy with the mechanism I turned to the aesthetics of the device.  Initially I had planned to keep the natural grenade look to appeal to the aesthetic of repurposed military hardware.  This can be seen in bottle openers made from .50 cal cartridges or pens made from hunting rifle casings or even artillery shells crafted into art by soldiers during both world wars. [3]

Artillery shells

Decorated artillery shells at the Arizona Copper Art Museum in Clarkdale [3]

While discussing our projects my teammate Chip suggested that I paint it to resemble a traditional decorative nutcracker.  I really liked this idea as it would help to identify the function of this strange little gadget (hopefully detracting from the alarm most people understandably feel when they see a grenade) and because it leans towards a strange militarized Christmas aesthetic.  This military Santa Claus style has surged in the last couple of decades in conjunction with the “War on Christmas” propaganda that has happened during that time frame.  Once painted it was clear that Santa would be dropping these nutcrackers from his sleigh onto the naughty boys and girls of the world.

SantaGun2011

Santa, ready for war

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Nutcracker fully painted

Overall I was fairly happy with the outcome of my project.  Functionally the mechanism is very consistent, though not perfect.  Before any testing I expected the striking lever to obliterate whatever nut I placed in its path.  This turning out not to be the case was great as it resulted in a genuinely useful device that can soften the nut up for easy opening.  Aesthetically I am very happy that my vision of a plain grenade was superseded by the classic nutcracker aesthetic.  In addition to making the grenade a bit less threatening it also reminds me of childhood Christmases.  Adding details like teeth and tonsils to the “mouth” of the nutcracker or the gold epaulets and buttons on his jacket made it look goofier in the best possible way.  I had not painted in a long time so this part of the project was a lot of fun!

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Closeup of nutcracker’s “face”

Despite all the successes there are some issues with the nutcracker.  The mechanism is difficult to reset and, due to the naturally low cycle numbers grenade trigger mechanisms commonly see, the spring and pin are already showing some signs of wear.  Similarly the paint around the impact area of the striking lever and anywhere else that sees contact with other surfaces has already mostly chipped away.  It may be possible to rectify this with a primer appropriate for painting onto steel.

2016-02-03 17.58.01

Image showing how paint has deteriorated after 3 days of use

Going forward I may look into improving the paint job and then this will likely come out every year around Christmastime when pecans are in season.  I don’t know if the grenade nutcracker is going to be the next .50 cal bottle opener but this was a very fun project and I look forward to displaying my, more functional than most, holiday nutcracker.

 

References:

[1] http://www.inetres.com/gp/military/infantry/grenade/hand.html

[2] http://www.germanclocksandgifts.com/nutcrackers

[3] http://www.copperartmuseum.com/#!military-art-room/c15a9

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41 Comments. Leave new

  • […] students chose military hardware as upcycle source material, and made benign objects from it, like Ethan Gehring’s nutcracker from a grenade casing, Shen Shu’s toy cannon, and Chad Alvarez‘s string of shotgun shell lights.      […]

    Reply
  • Ethan Gehring
    Anfal Abdulrahman
    February 13, 2016 10:52 pm

    Your iterative process was really interesting, your went though a lot, failures occurred but I like your persistence to keep on adding touches here and there. Nice work!

    Reply
  • Ethan Gehring
    Chip Bollendonk
    February 7, 2016 10:41 pm

    Ethan, here are some more in-depth comments about your project:

    I’m really glad that you stuck with this project and it turned out so well. I think that one of the coolest things about the project is you found a neat piece of engineering (the triggering system) designed for an extraordinarily destructive device, and translated it to a more harmless application. This in itself could be an aesthetic – its like abandoned tanks with flowers growing out of them, or art made from bullet shells. There is something so wrong about cracking nuts with a grenade, which also feels so satisfying.

    The paint job looks pretty great, again it is so interesting how it totally changes the mood of this device. I’m glad you went ahead with the Santa theme, and I do hope that future Santa will drop this into the homes of good and bad children alike so they can eat their pecans safely (?) and enjoyably throughout the holiday season.

    Nice work, and I will be interested to see if the mechanism wears out or not.

    Reply
  • War on Christmas aesthetic. ‘Nuff said. But seriously, this is definitely one of the most original ideas I’ve ever seen with a grenade! Maybe there could a part you can add to make the “reload” a bit easier or automated. Otherwise, I thought this was a seriously awesome project!

    Reply
  • Ethan Gehring
    Kenzy O'neill
    February 6, 2016 2:40 pm

    This turned out great, Ethan! I love that it’s actually a functional nutcracker, and that you painted it for that wonderful, Christmassy feel.

    Reply
  • Your project looks really cool. I liked the background story behind how you got your grenade and all that. I love the paint job on it and the rugged look. I also really enjoyed the war on christmas aesthetic

    Reply
  • You had the funniest presentation. Also, as a weapon of last resort, you can smash the nut with the grenade body!

    Reply
  • Ethan Gehring
    Ashley Zimmerer
    February 3, 2016 9:17 pm

    Wow, this was both cool and wild. At first it kind of looked like a Pokeball. Maybe you should paint the pull part to look the the nutcracker’s hair.

    Reply
  • You should add the beard and try to make it look more like a nutcracker. You could make a whole set of war on Christmas nutcrackers!

    Reply
  • That is an awesome idea. Don’t go to the airport with it though :). It’s a great aesthetic. Maybe add a metal tip on the triggers so it functions consistently

    Reply
  • Ethan Gehring
    Nicholas Flood
    February 3, 2016 4:44 pm

    I like the “war on Christmas” look, but you could make it more obvious somehow. Personally, I would prefer the unpainted grenade look, but I like the joke. Very clever use of a grenade. Nice work!

    Reply
  • Ethan Gehring
    Anfal Abdulrahman
    February 3, 2016 2:45 pm

    Wow, this project is unique in term if its aesthetic and functionality. Got to say it did scare me a little though.

    Reply
  • Ethan Gehring
    Samantha Maierhofer
    February 3, 2016 2:07 pm

    Crazy idea but very cool final product. I would have never have thought of using a grenade as a nutcracker. I also like the design you painted on it to relate it to the traditional nutcrackers seen at Christmas!

    Reply
  • Ethan Gehring
    chris coffman
    February 3, 2016 1:53 pm

    Awesome idea, love the combination of breaking nuts and explosion.

    Reply
  • So fun, so creative! Santa should definitely throw these from his sleigh!

    Reply
  • Ethan Gehring
    Sreyas Krishnan
    February 3, 2016 12:37 pm

    “The war on christmas” HAHA AWESOME! This would be a great christmas tree ornament too!

    Reply
  • So cool. Works really well too- perfect amount of power to crack it without destroying the edible part!

    With some rope for the beard, that’s going to be an awesome holiday decoration you’ll be able to talk about for a long time… haha!

    Reply
  • This is awesome! I love the US military vibe, and the Christmas Aesthetic. If the cracker part does not work properly, you could just smash the nut with the bottom of the grenade.

    Reply
  • Ethan Gehring
    Chip Bollendonk
    February 3, 2016 12:34 pm

    This turned out really well! I’m proud to be a member of your team. I’m glad that you painted it and think that the buttons look really nice and help identify it as a nutcracker. The addition of a beard would be cool, but I wouldn’t recommend doing the cotton ball approach as it would probably disintegrate pretty quickly. Nice work.

    Reply
  • Ethan Gehring
    Brittany Warly
    February 3, 2016 12:34 pm

    First off I was terrified when you went up to the front of the classroom holding a grenade, but cool idea. I never would have thought about something like this!

    Reply
  • Ethan Gehring
    Thomas Brunsgaard
    February 3, 2016 12:34 pm

    Very unique idea! I want to check it out up close. It will be a great conversation starter, and I love that you combining two polar opposite concepts (holidays and military weapons).

    Reply
  • Ethan Gehring
    Meridith Richter
    February 3, 2016 12:33 pm

    I love the idea of militarized Christmas. The painted outfit truly adds to the whole thing.

    Reply
  • Ethan Gehring
    Brendan Warren
    February 3, 2016 12:33 pm

    Bummer it didn’t work in the demo! Well done turning something that is generally seen as simply utilitarian tool and turning it into a playful household item.

    Reply
  • I really like how creative this is. Most nutcracker, are decorative and I feel like that they would break so I really appreciated that it actually works.

    Reply
  • Best project ever. I like that you painted it in festive colors. Would be cool to see it in more glossy colors, but I like the idea.

    Reply
  • Clever idea – terrifying when you pulled the pin – but clever. Entertaining presentation as well.

    Reply
  • What a wacky idea! Grenades are not the first thing you think of when talking about nutcrackers, so it’s great that you combined them together so effectively. If you decide to refine your design, fine adjusting the tension of that torsion spring to crack nuts open more consistently would be a good thing to work on.

    Reply
  • Lol great reuse of a grenade. If only the demonstration worked

    Reply
  • Ethan Gehring
    Shawn Sprinkle
    February 3, 2016 12:32 pm

    Very original nutcracker! I like how you painted it like a traditional nutcracker, love the whole war on christmas theme

    Reply
  • Ethan Gehring
    Peter Brunsgaard
    February 3, 2016 12:32 pm

    That’s a super cool idea, and the end product turned out really well.

    Reply
  • That is both the most terrifying and glorious project thus far. I would recommend making the reuse process easier. Decorating him was hilarious and wonderful. Good job.

    Reply
  • I love the creativity behind your design. It is such a unique perspective.

    Reply
  • Ethan Gehring
    Joseph Yoshimura
    February 3, 2016 12:32 pm

    I really enjoy the fact you took something that would typically be looked as incredibly dangerous, but made it something fun and useful. Also, your presentation was pretty fun.

    Reply
  • Ethan Gehring
    Jakob Oreskovich
    February 3, 2016 12:32 pm

    Great redesign of an already existing product. A beard would be a nice touch. I’d like to see more of this militarized christmas aesthetic.

    Reply
  • Ethan Gehring
    Jacob McCormick
    February 3, 2016 12:32 pm

    I think it’s cool you made use of the strong torsional spring already in the grenade; the paint job is also awesome.

    Reply
  • one of the most creative ideas so far and still works as a nut kracker!

    Reply
  • Sweet idea! How expensive are old grenades – would you be to make multiple of these relatively cheaply?

    Reply
  • Dude, you are hilarious. This project is really funny, and as long as it works, I could see it being a great novelty item that somebody would buy.

    Reply
  • Nuts should be hard to eat. Bravo!

    Reply
  • Very creative use of the grenade. Love it

    Reply
  • Ethan Gehring
    Rachel Grosskrueger
    February 3, 2016 12:31 pm

    I think it would be really cool to build a typical nutcracker frame around this design! I love the idea of upcycling a hand grenade!

    Reply

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