Introduction: Knex Desktop Trebuchet

Picture of Knex Desktop Trebuchet

A small-sized trebuchet with an okay range.

Step 1: Make the Base

Picture of Make the Base

Make as the picture below shows.

Step 2: Make the Sides

Picture of Make the Sides

Make two of the following sides as the picture shows.

Step 3: Make the Track for the Trebuchet

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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.


bchen6 (author)2011-07-21


bchen6 (author)2011-07-21


bfwitt (author)2010-12-18

what did you use for weight

runedevil98 (author)2010-08-28

is this hard to make

Not Very... Just a lot of parts

TOCO (author)2008-12-17

How did you make it virtual looking? It is really cool.

GeekBeam (author)TOCO2010-06-01

the program is named MLCAD

rybubbles (author)2009-10-12

how did you make the pictures cartoonish!?!?!

NYPA (author)rybubbles2009-12-27


GeekBeam (author)NYPA2010-06-01

 correction: mlcad is the name of the program

GeekBeam (author)rybubbles2009-12-22

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

GeekBeam (author)GeekBeam2009-12-28
yordi193 (author)2010-05-13

 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)

sak-j (author)2008-03-29

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

GeekBeam (author)sak-j2009-12-28

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

dsman195276 (author)sak-j2008-03-29

look it up, it a type of knot.

Bartboy (author)dsman1952762009-07-03

And a band :P

TOCO (author)2008-12-17

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.

GeekBeam (author)TOCO2009-12-22

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

lilparker72 (author)TOCO2009-07-10

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

guy-man (author)2008-04-20

where do you put the slip knot?!?

tribalmaggot (author)guy-man2009-11-14

put it round your neck and the other end around a tall beam =)

me003 (author)2009-07-28

i cant get it to fire right... mainly because i dont know where to put the slip knot... 7/10.

lilparker72 (author)2009-07-10

the slip knot part is really makin me crazy. i cant figure out where it goes or how to do it

BobicusIX (author)2008-06-06


csn1106 (author)2008-05-06

its just a loop

pls (author)2008-04-16

good idea

gmjhowe (author)2008-03-28

perfect! great for defending against the onslaught of knex pistols!

thebboy (author)2008-03-27


I_am_Canadian (author)2008-03-27

Very nice! i likee it a lot. nice to have a change from "easy simple knex pistol". good job

dsman195276 (author)2008-03-27

there we go! a nice and cool little project! +1 fav

About This Instructable




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