Introduction: K'nex Wheel Launcher

Picture of K'nex Wheel Launcher

I originally designed and built this rubber-band crossbow gun back in 2008, before I had discovered 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

Picture of 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

Picture of The Side-bars

Step 3: Trigger and Belt Clip

Picture of 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

Picture of Its Just a Front

Step 5: Putting It Together

Picture of 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

Picture of 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...


TheUnfortunateHobbit (author)2013-12-29

awesome gun!

Knex4Life23 (author)2012-08-04

you have a lot of wheels

cookiemaker (author)2010-12-02

I'm trying to make one that puts a spin on the wheel.

zap8004 (author)cookiemaker2011-03-18

try attaching a tan piece to 1 side so the wheel hits it & spins

PJEC (author)cookiemaker2010-12-21

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.

Ymerej88 (author)PJEC2011-01-08

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

cutler27 (author)cookiemaker2010-12-30

try causing friction on one side of your wheel for it to grip it into a spin

Have you tried using friction to grip the wheel as you rotate it before release?

barfingdog (author)2011-02-05

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

barfingdog (author)2011-02-05

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

barfingdog (author)2011-02-05

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

zap8004 (author)2011-01-07

can u substitut the quad-plate

Ymerej88 (author)zap80042011-01-07

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.

lhinkle (author)Ymerej882011-01-29

does the blue=red

Can you give me a picture of the substitution?

OK, here it is. I hope this helps you :)

Great! Thanks and that was an original idea *5

H1T4TCH1 (author)2011-01-15

I build it and it's amazingly innovative!

Ymerej88 (author)H1T4TCH12011-01-15

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.

H1T4TCH1 (author)Ymerej882011-01-19

Yeah, i'll look what I can do for ya ;-)

An Villain (author)2010-12-26

Cool. Also, 777th view.

BalintRules (author)2010-12-21

looks cool, 5*

(For a second I thought that it wasn't featured, I would've gone "hey dude! Why isn't this featured?")

Ymerej88 (author)2010-12-10

This was an older design that featured dual handgrips and a complex trigger system that never quite worked properly.

instruct39 (author)2010-12-07

not bad, looks cool!

Sorunome (author)2010-12-01


Lewis Hamilton (author)Sorunome2010-12-04

dude thats awesome

altair ibn la ahad (author)2010-12-02

yay its awesome

mulletman6 (author)2010-12-01

Looks quite kool. What sorta distance does it shoot?

Ymerej88 (author)mulletman62010-12-01

I just tested it a moment ago, and when resting on the floor it angles up at 20°.
From this position the wheel travelled 3.9m before touching the floor, but it can go over 5 metres when fired from chest height.

DJ Radio (author)2010-12-01

Congrats on the feature! I like how this is wrist mounted. I wonder if you could make it repeat. The design isn't bad but I've seen some models that are just as good and the idea isn't original.

~KGB~ (author)2010-12-01

that iz epik! 5*

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