K'nex Ball Machine Lift Instructions: Full Automatical Giant Ball Catapult

About: I'm french, I live in a house, I love build with K'nex and Arduino, I have a YouTube chanel, and for Halloween, my garden become an haunted garden...

This my new lift, the Giant K'nex Ball Catapult, in my room it shot to a distance of 4 meters (because my room is too small), but I think it must shot to a distance of 10 meters, it only contains a motor, it's totally automatic, the arm is tracted by a nylon cable, but the shot is very hard to regulate, because the catapult shot creates a role-back, and the elastics extend. But the final result is just awesome !!!

I've build a second version, it's a more economize pieces version, and I've add some improvement.

And now, get started to build it ! (it's the second version)

Step 1: Part List and Caution

Before starting to build the catapult please read it atentivly:

WARNING! It's a dangerous build, please don't try to build it if you're under 14 years old, or talk with your parents about it.

WARNING! The nylon cable cut very strongly when the catapult is shooting! (it should cut plastic !)Don't put your finger or other object between the catapult arm and the nylon cable, and in the mecanism nether!!!

WARNING! No one should be placed in front of the catapult when it's in course of arming, or when it's shooting!

If you build the catapult, and that you're not respecting those rules, it's at your own risk !

In the event of an accident I decline any responsibility !

PART LIST:(for the basket version with the lift)


-grey: 79

-red: 121

-yellow: 172

-blue: 364

-white: 164

-green: 210


-blue 3d connectors: 151

-purple 3d connectors: 242

-white: 33

-yellow: 137

-green: 24

-red: 111

-orange: 67

-light grey: 12

-dark grey: 72


-medium yellow gear: 3

-medium red gear: 7

-small blue gear: 3

-lock clips: 20

-pink straight rod: 5

-grey spacers: 51

-blue spacers: 56

-green motor: 1

-red double compartment motor: 1

-Y clips: 15

-nylon cable (10 kg chargeable) : 1 meters (3 feets)

-chain link: 65

-black hinge connector: 2

-blue hinge connector: 2

-cushion (35 on 35 cm): 1

-big brown scotch: 1

-rubber bands (120 on 1,8mm): 13

-rubber bands (60 on 1mm): 2

Step 2: Frame of the Catapult (part 1)

build the three part of the two big parts of the first part of the frame.

assembly the two big parts.

Step 3: Frame of the Catapult (part 2)

build the three parts of the two big parts of the second part of the frame.

assembly the two big parts.

Step 4: Assembly the Two Parts of the Frame

Assembly the two parts of the frame.

Warning, the frame isn't stable !

Step 5: The Arming Mechanism (part 1)

Build the reel of the catapult, for roll up the nylon cable.

Step 6: The Arming Mechanism (part 2)

build the second part of the arming mechanism.

Step 7: The Arming Mechanism (part 3)

In this step you need a teflon roll or Uhu patafixe.

Step 8: The Arming Mechanism (part 4)

build the end of the arming mechanism.

Step 9: The Firing Mechanism (part 1)

build the first part of the firing mechanism

Step 10: The Firing Mechanism (part 2)

build the end of the firing mechanism.

Step 11: The Catapult Arm

build the arm of the catapult.

attach the catapult arm.

placing the nylon cable.

adjusting the nylon cable.

Step 12: Placing the Elastics

Place the double-elastics.

And equilibrate them.

Step 13: The Anti-tangle System (optional)

This is an optional step.

But it must be useful !

Step 14: The Ball Dispenser Tower

Make the tower of the ball dispenser.

Step 15: The Ball Dispenser (part 1)

Make the first part of the ball dispenser.

Step 16: The Ball Dispenser (part 2)

Make the second part of the ball dispenser.

Step 17: The Ball Dispenser (part 3)

Make the final part of the ball dispenser.

Assembly the tower with the ball dispenser.

Step 18: Assembly the Ball Dispenser Tower With the Catapult

Step 19: The Tower of the Basket

Build the basket tower.

Step 20: The Basket (part 1)

Build the first part of the basket.

Step 21: The Basket (part 2)

Build the second part of the basket.

Step 22: The Basket (part 3)

Build the third part of the basket.

Step 23: The Basket (part 4)

Build the final part of the basket.

Step 24: Place the Catapult and the Basket Tower

Place the basket tower.

Place and attach with scotch strip the catapult.

Step 25: Well Done !

So, it's finally finished !

If it's doesn't work, you should tell me your problem !

Epilog Contest 8

Participated in the
Epilog Contest 8



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    9 Discussions


    2 years ago



    2 years ago

    Brilliant! Was hoping you were going to make instructions. Voted too!

    1 reply
    Lexi Knex

    2 years ago

    ah bon ? on m'a jamais averti de ne pas construire un knex pcq j'avais pas l'age xD. Comment cela pourrait il me blesser ? les doigts ?

    1 reply
    Mister GearsLexi Knex

    Reply 2 years ago

    ba le truc c'est que quand la catapulte tire, le fil de nylon se déroule tellement vite et violement que sa entaille les tiges de K'nex, alors apres si tu veux mettre tes doigts dedans, c'est toi qui voit.


    2 years ago

    Holy COW!!!! This is AMAZING!!!! Thanks for the instructions! I LOVE THIS! IT'S EPIC!!!

    1 reply