K'nex Wheel Launcher




I originally designed and built this rubber-band crossbow gun back in 2008, before I had discovered Instructibles.com or seen any other k'nex gun ideas. I noticed one day that I had a sizeable collection of wheels, so naturally I just had to ask myself "What can I build to shoot them with?" Thus began several days of thinking, building, testing, and modifying; until I arrived at a solution that I deemed adequate for my needs. Since then, it has undergone several major revisions, such as the repeated tweaks to and eventual complete rebuild of the trigger mechanism. The belt clip is another recent addition, borrowed from a gun holster.


grey: 6
purple: 2  (long & bendy)
red: 5
yellow: 2
blue: 9
white: 17
green: 16

white: 2
blue: 3
yellow: 7
green: 10
red: 7
light grey: 12
dark grey: 3
orange: 6
tan: 4
Y: 3
hinged: 2
-TOTAL: 59

blue spacers: 58
Silver spacers: 16
1 grey gear
1 small tri-plate
1 small quad-plate
1 large rubber band
1 small rubber band

Step 1: Start Here

When built correctly, you should have symmetrical parts at the end of each step.

Hopefully, anyone will be able to build this from just the pictures, but if  you have any questions, or something is unclear, please let me know and I'll try to clarify any issues.

Step 2: The Side-bars

Step 3: Trigger and Belt Clip

 I designed the belt clip while making a K'nex holster for my Lego gun.
If you have a wrist-band, slip it over the tan connectors (while its on your arm) and then you can fire the weapon single-handedly by flexing your wrist downwards.

The launcher could be loaded when you attach it to your belt . Without due caution, you may accidentaly shoot your foot (or the foot of a random person passing by).

Step 4: Its Just a Front

Step 5: Putting It Together

Do not expose the device to temperatures above 600°C as this may cause degradation of firing precision or, in semi-rare cases, complete loss of functionality.
Do not aim the device at humans (this includes your sister), animals, computer screens, windows, rare vases, etc.
Do not look into the operational end of the device, even partially.

Step 6: The Building Is Over Now

I, for one, congratulate my K'nex-gun-building Instructables fans!

Very good. You are now in possession of a K'nex wheel-launching device. With it, you can fire your own projectiles. These three-dimensional wheels have proven to be mostly safe. The device, however, has not...



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    31 Discussions


    Reply 8 years ago on Introduction

    To do that you could try making one side of the rubber band more tense than the other. In theory that would make it work.


    Reply 8 years ago on Introduction

    The main problem is that currently the wheel rotates freely, so the tension on each side is always equal.


    8 years ago on Step 5

    awww.. i was just going to kill my sister with this!


    8 years ago on Step 4

    is there a way to replace te lite blue thingeys, i don't have them


    8 years ago on Step 4

    well now all finish this sentace: with this awesome wheel launcher i am going to...


    Reply 8 years ago on Introduction

    Yes, certainly.
    I used the plates because they make it a bit stronger, but you could substitute either plate with the corresponding connector and green rods.


    Reply 8 years ago on Step 6

    Thanks, its great to know that people are actually building this. (not that I ever really doubted it :)
    I'm glad you like it; I'd love to see any modifications and/or improvements that you could make :D

    I haven't done much K'nexing lately due to the busyness of real-life, and a fractured clavicle, but I do hope to post some more instructables sometime.