Customizable Knex Lock and Key (Prototype Cylinder Mechanism)

About: Im Killer~SafeCracker, I started using Instructables in 2009. I mainly post in the Knex world, but I venture out sometimes. Check out all my instructables, you wont be disappointed! I live for music and I p...

Hello Boys and Girls!

     Thanks to the addictive nature of designing and building with Knex, I have spent the last two days designing a new type of lock and key.  My goal was to create a lock that works as much like a cylinder lock as possible. I also wanted the key to be unique to the individual lock. By using tumblers of different sizes, you can customize the key. The prototype pictured only has two tumblers, but can be built to have as many as desired.

      When you put the key in the lock's body and turn counter-clockwise the teeth on the key will push the grey wheels up. The wheels give a smooth surface for the key's teeth to turn against. Sitting on top of the grey wheels are plates that act as the tumblers. To customize the lock you lay an orange connector on top of the tumblers that correspond with the short teeth on the key. When locked, the top of the tumblers will be be at different heights. When you turn the key, the tumblers will all rise to a uniform height.  That pushes a connector, that is on a pivot, up. This can be used to unlock a pin, or whatever you want to connect to it.

One thing I did not want to do was use any rubber bands. I got around this by using flexible rods to keep pressure on the tumblers so it will re-lock when the key is removed. Also, unlike most of my previous builds, it uses no modified parts.

     I would love to hear any feedback you have to give.
Until next time,



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    31 Discussions

    A decent horizontal magazine gun, as many have been attempted, but minimal success has been achieved. Or if they do function smoothly they require to many pieces.

    awe >.<
    How about some small gadgets a lock? :P

    Erm, more like, um, i once tried myself on making a rubiks cube out of knex ^.^


    3 years ago

    Your builds are great and tbh I'm annoyed with all the negative feedback you are getting. Keep going :)


    3 years ago

    could you make a low part asault rifle with underbarrel mounted gernade launcher?


    4 years ago on Introduction

    im just asking,do u ever POST ur things? because i've followed u and i need the instructions to make there unparalleled contraptions.


    5 years ago on Introduction

    lazy builder! lazy builder! u dont put any instructions in ur inventions! lolololololololololl

    hahaahahahahahahah xD

    Excellent mechanism. The only thing that would make it cooler is to do something with the yellow rod to make it actually able to lock things. If you were to do that, you'd have to work on making it ridiculously compact to make it capable of being more like a real lock. I see that you and Red wanted to a collaboration; maybe you could do that. It's just a suggestion, of course, but it'd be really cool to see it done. Oh, how I wish I had my K'nex back. :p

    2 replies

    There are many different ways to actually make it lock something. I'll leave that up to whoever wants to make something with it :)
    I mean these are Knex, any lock will be relatively east to pick. I originally wanted to make a real safe, but realized that was kinda pointless seeing they are Knex. Haha
    If i was to work on a gun concept, what is a concept that people really want to see?

    I know what you mean regarding K'nex not being able to be a real lock, because people can take it apart. You already made a padlock that does pretty much what I described, and it is very nice.

    As for what the K'nexers want to see in a gun, it'd be an automatic gun that doesn't use the 'spray' method. The spray things are pretty much shotguns, anyway.

    (I did have a concept mechanism in my head before I lost my K'nex that would allow you to implement the spray mechanism in a pistol. It would be just like one of Red's many, many sidearm models, but with a trigger that would make it automatic and capable of stopping fire when the trigger isn't pressed anymore. Probably not what people would want, though.)


    5 years ago

    Could you make something in the gunning category? Nice work though.