Last year for Christmas one of my friends gave me a decommissioned or 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 on 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 this striking motion and for my upcycling project have decided to re-purpose this force for the greater good of cracking nuts.
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 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.
Initial testing did not show what I had hoped for. I expected the high force created by the striker spring to simply smash the test pecans into a bunch of pieces. What actually happened turned out to be better. Rather than sending pieces flying the small nub intended to strike the primer punched a small hole in the shell of the nut and in most cases caused a crack to form along the length of the shell. This is fairly ideal performance as the small crack is enough to allow the nut to be opened by hand with reasonable force.
Moving forward I plan to modify the top of the grenade to be able to hold the pecan in place without assistance. Once the nutcracking system is functioning properly I plan to paint the grenade and add some minor aesthetic touches to the top in the style of traditional nutcrackers.
References: http://www.inetres.com/gp/military/infantry/grenade/hand.html  http://www.germanclocksandgifts.com/nutcrackers