Introduction: Life Size K'nex War Cannon

Picture of Life Size K'nex War Cannon

Here it is the best of the best life size (or almost life size) war cannon. Yes I know there are lots of knex cannons on Instructables but this one is different from the rest. It looks like a cannon. It will shoot 60 - 70 feet with 2 rubber bands ,and will shoot though 4 pieces of paper. This does use ALOT of parts so I took the time to take a part count so you don't waste your time. It uses a more simple trigger Then IAC cannon but it(kinda) uses the same mech.

looks great
wonderful distance 60 - 70 feel with 2 rubber bands
will completely destroy 3 pieces of paper

uses a lot of pieces

Step 1: Part Count


76 gray

70 red

37 yellow

27 blue

55 white

100 green


17 white

40 blue

44 yellow

58 purple

70 green

27 red

6 gray

11 orange


4 gray clips

8 small gears

I can't give a number of spacers. Because the number will differ for each person.

18 black hands

2 rubber bands

Step 2: Wheels

Picture of Wheels

Okay you might recognize these wheels they are from IAC's cannon but I enlarged them by 5 times.

Step 1: build 2

Step 2: add rods to one of them

Step 3: Build 8

Step 4: connect both sides

Step 5: add rods with spacers to all of the spaces

Okay now do this whole section again.

Step 3: Barrel

Picture of Barrel

Okay I tried to do this as good as I could but it was very difficult for me to make this part of the Instructable.

PIC 1-2: build this part (it is the front of the barrel) PC 2 is of the same part upside down

PIC 3-4: build this. It is the middle part of the barrel.

PIC 5-6: build . This is the back part of the barrel and the firing mech

If you can't follow any of this Instructable let me know on my orange board and I'll try to help.

Step 4: Connecting the Barrel

Picture of Connecting the Barrel

Okay now we are going to connect the three parts of the barrel we just made.

Pic 1: connect the 3rd part with the 2nd

Pic 2: now connect the front with the rest.

Pic 3: you are done with the barrel it should look like this. ignore the bow thing we will make that in a bit

onto the next step. >>>>>>>>>

Step 5: Body

Picture of Body

Okay this is more easy.

Step 1: build 2

Step 2: build this little thing ( both rods need to be black)

Step 3: connect the last 2 parts we made together

Step 4: connect both sides with the red rods

Step 5: build

Step 6: add last part

Step 7: add gray rods

Step 8: add gray rods

Yay half way done!! onto the next step >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Step 6: Stand

Picture of Stand

okay. We are to the stand.

Step 1: build

Step 2: build

Step 3: connect both sides

Step 7: Connect the Parts

Picture of Connect the Parts

It is time to connect all the parts.

Pic 1: connect body and stand

Pic 2: add 3 spacers on each side.

Pic 3: add wheel and put however many spacers needed to fill the rod (will be different on each side)

Pic 4-5: now we are going to connect the barrel to the body.

Pic 6: Build

Pic 7: tie 2 rubber band together

Pic 8: add "bow" and rubber bands

Pic 9: build

Pic 10: build

Step 8: Loading & Firing

Picture of Loading & Firing

This is very easy

Pic 1: Load it like this.

Pic 2: pull rubber bands back and hook onto the ammo.

when you are ready to fire just pull out the pin.

You are done!!!!!!!!

Have a lot of fun!!

If you have any questions let me know.

Let me know what you think.


master-splinter306 (author)2015-07-13


knexinventer (author)2014-02-02

This was the first of the cannons that i built about four and a half years ago on this site.

bob the HUNTER (author)2012-03-10

dude this thing rocks just built but the only down side is that is does not shoot good for me

I built 4 of this but i didnt bulled the wheels so i took the cannon pieces and attached the barrels to my arm and walked to into the libreary with it....

Dr MonkeyMan (author)2013-06-25

I built this and i tested out how far the projectile would fly so i put it in our drive way and pulled the trigger and the piece flew out and hit a moving car. The person stopped so i pulled the cannon behind are car and waited for him to leave.

Sypran (author)2009-01-17

cool, I'm gona build this and put a seige on the playground fort hahaha

erikos kostarikos (author)Sypran2009-05-19

good idea
im gonna terrorisate the mcdonald's playground=D

sounds fun.... can i join in?

That's gonna be fun!!
Let's both build one and shoot children?

i would but im 3 years too late :3


knexgunbuilder217 (author)2012-07-24

do u have to use the flexi-rods for the barrel

skyfaller (author)2010-10-10

This is good!

You should check out I_Am_canadian's knex heavy cannon.

Brad G (author)2010-10-02

Modded this quite a bit, ALOT less skeletal it looks pretty awesome ;) fully metallic shoots a bigger projectile (like IAC Cannons) and the end of the barrel is modded a little, i will try and get pictures thanks for making this great cannon ;)

instruct39 (author)2010-09-07

you need cannon ammo not little tiny ammo u cant find after shooting it, other than that very cool! 5*

clader1 (author)2010-04-11

dude it doesn't go 60-70 feet. you lier i shot it it went 150-200 feet !!!!

dnmonsen (author)clader12010-06-19


matsermetsuiker (author)2010-01-23

lol XD its really cool!

Furloy (author)2010-01-09

 4.5 stars, it skeletonish

Killer~SafeCracker (author)2009-12-19

I gotta say it looks good. 4.5*

codemaster2590 (author)2008-10-27

i think that it is really cool but i do agree that it could use more reinforcement. I think that it would be cool if you made it a breech loading cannon if you made any mods to it.

knexkrazy (author)codemaster25902008-10-27

Thanks! I'm working on a second version that has more parts, but it takes a lot of pieces.

Bartboy (author)knexkrazy2008-11-30

Umm? "second version that has more parts, but it takes a lot of pieces." LOL


charlie farthing (author)2009-04-27

so how far can this canon shot 70 80 feet or is it a low range gunthat can only shot about 20 feet

Jesus. (author)charlie farthing2009-09-02

lol it say right there /\ /\ /\ /\ /\

Skreetsha (author)2008-11-03

Cool! A bit skeletony but, it probably functions as it looks, and that would be great :D 5 stars!

I_am_Canadian (author)2008-10-29

Oh yeah... Nice wheels Nice pictures.

alfpwns (author)2008-10-29


builder968 (author)2008-10-28

pretty cool. I know i dont have any howework tomorrow evening;might build.

builder968 (author)builder9682008-10-29

then again, i might not. might build on sunday(saturday i have a friend's party).

arrow shot (author)2008-10-28

nice, but i hardly believe that cannon barrel is life sized...maybe provide us with a picture? of the real thing>?

knexkrazy (author)arrow shot2008-10-28

This is the cannon I was modeling it after. Of course I can't go true life size without using a TON of parts. But, I called it life size because it is VERY big and looks pretty much like the real thing.

arrow shot (author)knexkrazy2008-10-28

Yeah, it actually is almost life sized...If i had to guess, i would say 5/8? Havent built this yet though, so idk...too many peices for me XD

apples!!!!! (author)2008-10-28

Now I don't know if I want to work on the one I wanted to....

yerjoking (author)2008-10-28

Wow, I'd just love to sit at the back then fire it at someones face, they'd get owned lol.

Master_Zane (author)2008-10-27

Sweet! Looks Great!

knexkrazy (author)Master_Zane2008-10-27


uguy (author)2008-10-26

Life size?

knexkrazy (author)uguy2008-10-27

I said in my intro that it was "almost" life size. Actually, it isn't too much smaller than some cannons, but obviously not "real" life size.

DJ Radio (author)2008-10-27

cool, also love the realism of a civil war cannon. 5*

knexkrazy (author)DJ Radio2008-10-27

Good, I'm glad you like it. I was trying to make it look realistic.

I_am_Canadian (author)2008-10-27

Very nice! A tad "Skin and bones", but there is no great way around that without using a load of pieces. Nice work!

knexkrazy (author)I_am_Canadian2008-10-27

Yes, I agree. I'm working on a second version that has more body to it. You are right though - it takes a ton of pieces to make it fuller. But, this one works very well and is a lot of fun to shoot.

pls (author)2008-10-27

thats looks great:)

the_burrito_master (author)2008-10-26

lol nice it v=could use some more detail/re-enforcing but pretty good.

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