Semi-auto Lego Rubber Band Gun


Introduction: Semi-auto Lego Rubber Band Gun

This is a semi automatic Lego rubber band gun that can also be easily changed to auto.. but then with rubber band guns semi automatic is more of a challenge to build- here's how I built my trigger mechanism... this is my remake of it that contains step by step pictures i hoped could be comprehended.. contact me with questions of comments please! =)
see it in action here :

Step 1: The Main Ideology Behind the Mechanism

ok so basically the way this works is mostly all int he gears- I have it geared so that whenever a rubber band is released (only one) the "trigger wheel" (grey beam in the middle of the sideways v) spins only once. so in other words one rubber band=one trigger wheel spin. Then the "trigger" (purple bent beam) is connected to a sort of ratchet mechanism that when I pull the trigger back it makes the ratchet release the trigger wheel which the rubber bands put enough force on to release one. Also I have a rubber band connected to the trigger (the trigger is just connected directly to the "ratchet"or "v" (because it wouldn't fit on the inside of the trigger frame because the two gears that hold the bands are there). soryr this isn't more detailed but if you ahve any questions feel free to ask.

Step 2: Have Fun!

I think loading is pretty self explanatory to any one with any experience whatsoever with rubber band guns; but what you do to load it is stretch the rubber band from the end of the barrel to the gear then you can pull the trigger in order to push the gear back too and I've had success with loading as many as 12. here's a video of me shooting it in my closet =P.



    • Make it Move Contest

      Make it Move Contest
    • Casting Contest

      Casting Contest
    • Oil Contest

      Oil Contest

    We have a be nice policy.
    Please be positive and constructive.




    cam I use a little...engrenage?

    i have a full auto rifle thats amazing for lego wars (kinda like knex/nerf wars but with lego guns)

    1 reply

    (note for future guns) ferret2992 first off you shouldnt leave the gun open or bable to c the rubber bands as when you are havig a war sum1mite hit the bands with 1 of theirs possibly letting the ammo fly off and getting shot repeated times at close range and with a powerfull gun (like my friends gun) so ya and if they are closed in they are less suceptible if they are enclosed and use a clip that holds bricks as shooting bricks is much more acurate(c my gun vid below if i can figure out how to post it) haha

    umm ill try to get it up soon but hte pics are takin forever to upload =/ umm Im afraid it may not work with different gears.. maybe 2 shots at once but you need my gearing set up in order for it to work semi-auto.

    2 replies

    if you can only make it move a minimum of like 3 notches just put rubber bands every third one.

    i can't get it to work, and i can't understand the directions.

    lik wen r goin post the more detailed one; ru goin to be posting it a few days, weeks or wat! p.s. can you show it with different gears i have the big one but the 3 smaller ones, maybe the ones from a bionicle ?

    hold on im gonna upload a much more detailed one in a little while.

    for everyone wanting more detaild instructions I think I'll edit this and make a more detailed set of instructions.. sorry it took me so long to get around too.

    I believe from either lego mindstorms or from some random lego technic or lego designer set

    wow you have no idea how long ive been trying to design a trigger mechanisim for my lego gun. i think im gonna use this. thanks

    1 reply

    sweet, no problem.. glad to be of help =]

    The pictures aren't very descriptive, can you post instructions?

    oo00oo im making a semiauto knex gun (thompson smg[body] + colt revolver[firing mechanism]) ill post when im done... Then ill be out of the unposting looseriness :)

    2 replies

    the "body" and mechanism should of read (body) and (firing mechanism) but i used square brackets

    it fires blue rods, not bands but is easily modded for bands