Introduction: Reaper Crossbow

Picture of Reaper Crossbow
So here it is, one of my greatest crossbows ever (V5 in the series), it employs four rubberband strings, which uses a completely new double trigger system, which holds arrows that are at full power and if one wants a little less power, one can lock two arrows in the trigger and use 2 rubberband strings for each arrow.

The absolute full power of this monstrosity is reached by removing the trigger system, which enables it to use 4(!) arrows, which it can fire in a rain of doom (One could call it a repeater crossbow actually). And if one does not use the trigger one needs to put the Reaper on your arm, otherwise it is too heavy to hold on to with one arm.

The distance it fires outside is like most long range knex guns very dependent on the wind, if the arrow has a good tailwind it can get ~200 feet without trigger.

Don't forget to rate :D
Enough talking, now get building :o

A video of the Reaper shooting at chipwood.
It pierces straight through it is not cardboard :D

Step 1: The Pieces List

Picture of The Pieces List

Minimal Pieces Needed:


Blue 3d connector: 88
Purple 3d connector: 60
Yellow connector: 51
Red connector: 8
Green connector: 4
White connector: 16
Light grey connector: 10
Orange connectors: 18
Grey connectors: 2


Green rods: 113
White rods: 130
Blue rods: 82
Yellow rods: 6
Red rods: 29


Wheels: 8
Blue spacers: 12
Grey spacers: 8
Rubberbands: 12

Recommended Pieces Needed:


Blue 3d connector: 88
Purple 3d connector: 60
Yellow connector: 73
Red connector: 12
Green connector: 10
White connector: 16
Light grey connector: 10
Orange connectors: 24
Grey connectors: 2


Green rods: 117
White rods: 161
Blue rods: 94
Yellow rods: 22
Red rods: 33
Grey rods: 6
Bendy grey rod: 6


Wheels: 8
Blue spacers: 12
Grey spacers: 8
Rubberbands: 16
Small panels: 6

And ofcourse "some" extra pieces for arrows.

Step 2: Building the Bow

Picture of Building the Bow

Only build what is centered on the picture and I will use a letter system to help putting it together.

Picture 1: Start off by building this 1st lower bow part(A) Don't forget the green rods on top!

Picture 2: Build this 2nd lower bow part(B).

Picture 3: Build these higher bow parts(C).

Picture 4: Add the parts A and B together. Which is now called AB.

Picture 5: Add a red rod to the part AB.

Picture 6: Add these blue rods to the part AB.

Picture 7: Add the parts C to AB as shown.

Step 3: Rubberbands Onto the Bow

Picture of Rubberbands Onto the Bow

This step is pretty frustrating, because putting on 4 strings of rubberbands is very hard ( Needs to go one by one unless you are good with knots :D ).

Picture 1: Add these to the bow (ABC).

Picture 2: There are 4 rubberband strings here, one is already on the bow.

Picture 3: Pick up one string of rubberbands and force them behind the wheels and put them onto the blue rods, do this 4 times and on both sides.

Picture 4: This is how it should look like.

Be very careful with the rubberbands....unless you liked this step alot :).

Step 4: Building the Handle

Picture of Building the Handle

An easy step to recover from the last one :P

Picture 1: Build these outer two parts (D).

Picture 2: Build the middle piece (E).

Picture 3: Connect the white rods of the outer parts (D) to the middle part (E).

Picture 4: Add all the red rods (to DE) as shown on this picture.

Picture 5: Connect the handle (DE) and the bow (ABC) to each other as shown in the picture.

Picture 6: It should look like this.

Step 5: The Trigger System

Picture of The Trigger System

Picture 1: Build these parts (F).

Picture 2: Connect the parts (F) like following.

Picture 3: Same as picture 2.

Picture 4: Build this part (barrel) (G).

Picture 5: Same as picture 4.

Picture 6: Build these two triggers (H).

Picture 7: Same as picture 6.

Picture 8: Add the triggers (H) to the barrel part (G)

Picture 9: Two triggers connected (GH)

Picture 10: Build these little parts.

Picture 11: Add them to (GH).

Picture 12: Same as picture 11.

Picture 13: Put a rubberband here.

Picture 14: Sorry for blurry picture, just fit as many red rods as you see fit (to part F), but don't forget the marked ones. And don't forget to put the trigger (part GH) in :P

Picture 15: Same as picture 14.

Picture 16: Connect the trigger (GH) to the handle (DE), which is connected to the bow (ABC).

Step 6: Extra Support and Decoration

Picture of Extra Support and Decoration

I would recommend building the extra support, as I haven't used it without it :P

Picture 1: Build these pieces for decoration.

Picture 2: Attach them like so to get a very clean looking crossbow :D

Picture 3: This is the extra support. I am not sure, but I think one can change the bendy rods for normal rods.

Picture 4: Attach them like so.

But what's that? There is more? Go to the next step. :P

Step 7: Types of Ammo and Loading

Picture of Types of Ammo and Loading

Wow, it can fire too! :o

Picture 1: Read the markers to see their power and speciality.

Picture 2: How a standard ordnance trigger arrow is loaded.

Picture 3: How one loads two standard ordnance trigger arrows at the same time.

Picture 4: Where to snap off the trigger.

Picture 5: How to hold without trigger.

Picture 6: How to load a multi arrow shot.

Picture 7: Fully loaded and ready to do some nasty damage :P

I am not liable for any damage you cause with this massive thing and never fire a piercing arrow at living creatures as it may pierce through flesh (Not going to test that lol..)


linton85 (author)2011-04-11

Hello i know this is very old now but i was wondering if the grey spacers = 3 blue spacers because when i put from bottom to top with the wheels like this if it is correct 1 grey spacer, 3 blue spacers,2 wheels, 2 blue spacers, 2 wheels, 1 grey spacer, 3 blue spacers. When i try and connect part ab and c together it doesnt fit help thanks

Wicky (author)linton852011-04-11

Wow, I took bad pictures ;x

Bottom to top:
2 grey spacers
2 wheels
2 blue spacers
2 wheels
1 grey spacer
3 blue spacers

Its a 'red' rod in size.
4 wheels
3 grey spacers
5 blue spacers

linton85 (author)Wicky2011-04-11

Thank you for replying so quickly I had it in the order you said but when it's put together ab + c with the red rods with stuff between it, doesn't clip together because it's to big I have taken out some spacers to make it fit also what size rubber bands did you use thanks once again

Wicky (author)linton852011-04-11

These rubber bands did not have any size rating, just cheap standard ones.

You want rubber bands that are pretty thin, the length does not matter, as you may make the handle longer to compensate for longer rubber bands.

willsor (author)2008-09-09

omg, can you please update pictures 10-15, cos I have absolutely no idea how to put the trigger bit onto part F

Wicky (author)willsor2008-09-09

I am sorry, but have you seen when I made the instructable? By now its already taken apart...and why didn't people complain before?...Onky option is to look more carefully =/

guy-man (author)Wicky2011-03-01

Update pics 4 and 5...........please?

epicbobman52 (author)2011-01-07

is it possible for me to build this with less wheels ( i only have 4 :( )

other than dat nice gun!

blak jeroe2 (author)2010-07-27

hey wicky. i made changed my reaper and know it have new abilyties. - new trigger system (1 bullet trigger but it shoots even farther) -handle (so i can run with it easyr and easy for trigger system) - the bow ( it is a lot stronger now i cccan show u the picturres tomorrow

joeyay (author)2009-05-12

that is gypsum board not plywood. still crazy bow i dont have enough pieces:(

Wicky (author)joeyay2009-05-12

My vocabulary isn't that great, thanks for letting me know, too lazy to fix it though ;P

What about this one? Without extra things like stock and then the smallest bow?
Power could be increased, but requires sturdier bow.

joeyay (author)Wicky2010-07-23

got more peices, built it. amazing

blak jeroe2 (author)2010-07-16

i made this one to it's fantastic. i killed abird with a piercing arrow. i have add 1 piece it's a standart so "the reaper" that standart make it easier to shoot from te ground. wickky if you agree with it i can let you see. wicky you're fantastic at making knex weapon

Wicky (author)blak jeroe22010-07-19

Feel a bit sorry for that bird..but its in the name of science! =x Might pick up building again soon, haven't touched knex for at least 4 months.

brycerogers289 (author)2010-06-05

this is a awesome crossbow shot through my wall snd i killed a squirel today

Joseph Mendoza (author)2009-12-10

Wicky, could u post mybe a miniture version of the reaper?I dont have that many pieces so maybe please.

Wicky (author)Joseph Mendoza2009-12-11

I have build loads of mini versions, just none posted, here is three different ones, 1 after the blockhead, 1 after the reaper and one is just a random one.

I can make a better one as soon as my k'nex is unpacked from moving =/

P.S.: It would be hard to make it smaller than #1 though =o

An Villain (author)Wicky2010-05-11

Mini blockhead is cool looking.

Joseph Mendoza (author)Wicky2009-12-13

could u make an instructable for the mini blockhead.Thats probably the only thing i could make.

shane0137 (author)2010-04-24

first i want to say this is the best knex gun/ crossbow ever and secondly with the normal arows i put the vertical so i use both sets of bands, it has a crazy whistling sound as they fly through the air

FlutterTree (author)2010-01-05

Oooo, powerful.

scaramouchew (author)2009-08-31

omg use ure brain if u dont wan it to brake then dont use the red connecttors

Wicky (author)scaramouchew2009-08-31

Any other connector will shatter just as easily, although it was my own fault that they went through chip wood and hit a wall =|

Killer~SafeCracker (author)Wicky2009-10-31

If it went through chip wood and didn't shatter wouldn't it just go through a wall.

Wicky (author)Killer~SafeCracker2009-10-31

The thickness does matter I guess, it was 5mm thick. Concrete walls on the other hand..seem a bit more sturdy =d

ant ant 33 (author)2009-10-27


jimbob the great (author)2009-10-25

Awesome gun!!!


Dvanex (author)2009-10-18

Mine exploded when I put the bands on, the blue 3d pieces pulled apart. Just a warning to anyone reading that maybe put some reinforcements on before stringing, I did and got it to work.

Dirtyboyy (author)2009-08-23

i don't have the gray long bending things , do you need that ?

Wicky (author)Dirtyboyy2009-08-23

It says in a note somewhere that you should use regular gray rods instead, because they are stronger.

NYPA (author)Wicky2009-08-30

would it be better to use flexi rods?

Wicky (author)NYPA2009-08-30

No, this bow isn't supposed to bend at all, so normal rods are recommended.

mettaurlover (author)2009-08-30

i gotta build this some time... and make it easier to aactually hold off table. maybe a two-hander.

Demolesher (author)2009-08-27

Lol I ran out of blue connectors in pic 2 of step 1. What sets did you buy?

Wicky (author)Demolesher2009-08-27

I stopped buying sets like 4 years ago, I got things like the solar energy sets and cars/ dinosaurs and loads more. Nowadays I just buy loads off ebay, its way cheaper and you don't get the useless micro knex and bricks.

therandomperson (author)2008-09-04

unlucky about ur broken pieces

xadevox (author)therandomperson2009-07-31

hi therandomperson! r u realy random?

therandomperson (author)xadevox2009-07-31

yah :)

Wicky (author)2009-07-01

Yeah this trigger has the same basic idea, but in a way earlier stage, it did however hold 2 arrows at once. The one on the BLOCKHEAD was made after 2-3 hours of hard thinking(man that trigger works great, still using it for every crossbow I make xD)

joeyay (author)2009-05-13

ya i went out and bought 2 new sets and now i built it. love it!!!!!!!!

Dirtyboyy (author)2009-05-05

wich one is better this one or blockhead ? please send a message , on this sit ? ( you know private message )

knex obsessed (author)2009-05-04

that happened to one of my purple 3d connectors nd a red connector when i used I_am_canadians v5 handheld cannon lol:D

deathshells (author)2009-05-03

i did that to my red corners with the striker pistol (freekin epic gun) although i dont think your supposed to load it with 11 #64 rubber bands. i broke the white snowflake that was holding them... small question how do you calculate the range? cause i think it was cefinitley impressive. nice crossboy by the way!

erikos kostarikos (author)2009-04-27

first i thought:i am sure that im gonna shoot on my brother. but then i saw that vid and i thought:nevermind. awesome crossbow.

Wicky (author)erikos kostarikos2009-04-27

A friend of mine was loading a bigger version of this and lost his nail because the ductape around the red connector failed =s
Don't shoot at people...unless you actually hate them...a lot xd

noob builder (author)2009-04-21

Guns are easy for me.. BUT CROSSBOWS?? naaahhh OMG. halp how to make a good one?! Im trying to make a LIFE size cannon. and i wanna make a crossbow/gun like thing that shoots Nerf Darts.. with a ROD in them.

Iridium7 (author)2009-04-01

(removed by author or community request)

345138 (author)2009-03-31

I mean not block head, the other.

345138 (author)2009-03-30

Wow, looks great, I built your other crossbow and was wondering if you can make something like the trigger on here.

Wicky (author)3451382009-03-31

If you mean like the trigger on the Blockhead...I think if you change the height of the wheels you just use that trigger on this one? =d

But I don't have any knex here, its at my other home, but on Saturday or so I will be making an Instructable on the Y-bow.

About This Instructable




Bio: I seem to like building crossbow shaped objects.
More by Wicky:Triple-shot CrossbowUltimate Crossbow V2BLOCKHEAD: Precision Crossbow
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