Knex Desktop Trebuchet

About: Some kid that likes creating things or viewing them to see the science behind them.

A small-sized trebuchet with an okay range.

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Step 1: Make the Base

Make as the picture below shows.

Step 2: Make the Sides

Make two of the following sides as the picture shows.

Step 3: Make the Track for the Trebuchet

Make three of the the first picture line them up put blue rods through the holes. make the sides for the track then add them to step two.

Step 4: Make the Trebuchet Weight

Make the picture below then add 7 large wheels to middle of the rod between the two gray connectors.

Step 5: Make the Arm

Make the 2nd-4th pictures then put them together like in picture 1 and after that add step 4 to make the final picture, then put picture 5 in the middle of picture 6 with the hole then get 4 blue spacers and 2 gray spacers and add them to the fifth picture.

Step 6: Putting It Together

Take step 1 and add the two step 2's that you make it like shown in picture 3. After that add a red rod where the picture shows. Then take the finished result from step 5 and add it to the top of the white connectors. Add step 3 to the bottom part like in the picture to finish the framework of the trebuchet.

Step 7: The Sling

Cut out a piece of string 15 inches long, then cut that in half. Get a piece of fabric, such as old pant legs, and cut out a () 4inX2in shape like the 2nd picture shows and cut little holes(near where the picture has them) in the sling that are big enough to fit the strings throughput both strings through then knot the crap out of it so it stays when pulled with a little force on both sides. Tie one string to the center hole in a orange connector and make a slip knot on the other side. Put the orange connector where it said that it would be explained.

Step 8: Loading/Firing

Drag the main arm back and put a red rod with a gray connector in the spot that the picture shows. Put a marble in the middle of the sling and fold the long part of the sling on itself. Then put that in the track making sure that the marble won't fall out prematurely. When thats done just pull the red rod and hopefully it fires.

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    31 Discussions


    Reply 9 years ago on Introduction

    he either 1 has a knex design program or 2 he got it off the knex websiteor 3 he went and got a cartoony camera used photo shop &degraded the pixel accuracy &put a white backround on it


    9 years ago on Introduction

     wow love you're design dude! with a little add on it fires about 25-26 ft !!! 
    (the wheels are the add on witch makes it fire just a little further)


    11 years ago on Step 7

    Tie one string to the center hole in a orange connector and make a slip knot on the other side
    I can't get this. What's a slip knot

    3 replies

    Reply 9 years ago on Introduction

    he probly means that it's supposed to slip off the green piece you put on top of the orange connector there's another version of this on youtube i looked up knex trebuchets ill get the link soon so just a sec


    10 years ago on Introduction

    I built two of these they are really fun. My brother and I had a war with them. You should try my amo without a sling.

    2 replies

    Reply 9 years ago on Introduction

    u cud also use a rubberband a blue non-hole piece put the rubber band on so it is wedged in between the blue pieces & the rod

    happy warring


    Reply 10 years ago on Introduction

    i couldnt get the slip knot thing with the sling but ur ammo works perfect