Intro: K'nex Chu-ko-nu/Repeating Crossbow
The Chu-ko-nu was created around 181-234 A.D. by chinese strategist Zhuge Liang. I have recreated his invention out of k'nex. I know that there are other repeating crossbows on this site, but i believe that this is the first instructable for a Chu-ko-nu style repeating crossbow. Here are some basic stats about my weapon:
Range: 30-40 feet. This is moderate range and I know most crossbows can shoot farther than this, but it is pretty good for the type of crossbow i think.
Magazine holds 9 red rods. But it only shoots 8 of them. The last one usually falls out because there is no pressure holding it in, but sometimes you may get lucky.
Power: It is not very powerful, but with a sharpened rod, you can get it to stick in cardboard
Piece count: (To make sure you have all of the pieces) Also if you do not have enough and would like to know other ways, please post on this instructable or pm me, i will be glad to help.
green: 35 + 2 + 10 + 68 = 115
white: 44 + 58 + 6 + 67 = 175
blue: 44 + 23 + 4 + 16 = 87
yellow: 8 + 68 + 0 + 3 = 79
red: 11 + 0 + 8 + 0 = 19
gray: 0 + 0 + 4 + 0 = 4
gray: 36 + 18 + 10 + 26 = 90
light gray: 0 + 0 + 2 + 6 = 8
orange: 9 + 0 + 0 + 37 = 46
red: 8 + 6 + 0 + 5 = 19
green: 8 + 18 + 4 + 30 = 60
yellow: 22 + 54 + 6 + 36 = 118
white: 8 + 20 + 2 + 5 = 35
purple: 40 + 0 + 2 + 8 = 50
blue: 1 + 0 + 2 + 0 = 3
blue spacers: 4 + 0 + 0 + 16 = 20
small wheels: 0 + 2 + 0 + 2 = 4
rubber bands: (this depends on the size) I used 4
Uses a total of 932 pieces. As you can see, the magazine uses lots of small rods, so it will be complicated. Lets start with that to get it out of the way.
Step 1: Magazine(part 1)
I am going to split the magazine into several steps to make it more manageable.
Note that I have the steps on the picture as well. If you find that easier.
1. Make 2 of these
2. Add white connectors and blue spacers to one side
3. Connect the other side
4. Make this
5. And this
6. And this
7. Connect the finished product from step three to step 6
8. Put step 4 and 5 on top of the other thing you built, and use white rods to keep the top layer attached. Also add green rods inside the green connectors, they won't stay right now, but they need to be there.
9. Get a strip of duct tape about that long and wide.
10. Wrap the duct tape around the bottom and up onto the green connectors like this
Done with the lower track of the magazine!
Step 2: Magazine (part 2)
Here is the actual magazine and the top part of the track.
1.Build 2 of these. (for the white connector on the right, all you need to do is cut off the bottom part of the connector, where it connects to other parts. A strong scissors should be able to do this. if not, just use a regular white, it will just put a little more stress on it, but it should be ok.
2. Build 2 of the small one, and 4 of the big one
3. Attach the 2 big ones like this on both sides
4. Build these, they are practically the same, except they should be opposite the direction of each other
5. Attach one of them like this, with the smaller piece i told you to build earlier inside the gap.
6. Attach the other one like this.
7. Build these
8. Attach the one like this, you might need to move the green connectors down to do this.
9. Attach it to the other one, it should look like this
10. Attach the blue and orange to the other side like this
11. Build 2 of these
12. Attach them like this, on one side, put an orange connector
13. Connect that piece with the other one, and put blue spacers in between
14. Build this
15. Connect it like this, it should be press up against the green
You are done with the upper track and the clip!, now to build the back and to connect everything
Step 3: Magazine (Last Part!)
You are almost done with the magazine, just a few more steps
1: Build 2 of these
2: Build 2 of these
3: To one of them, attach the thing you built in step one.
4. Attach it to the back of the thing you built in part 2 like this
5: Attach the other one below it.
6: Build 2 of these
7: Build 4 of these
8: Build 2 of these
9: Attach the things you built in the last 2 steps to 2 yellows like this. The yellows are attached to the back of the greens. Also add green connectors at the places show
10: Attach the things you built in step 6 like this, leave a small gap
11: Attach it to the other part like this
12: Add an orange with a green attached to the front of the magazine, the green should rest on top of the orange below it
13: Build 2 of these
14: Attach them like this, on both sides
15: You need to get a blue and cut it so it is a tiny bit longer than a white
16-17: slide the cut end into a red connector, duct tape it one so it cant move that much
18: Put the pin in the part you made in part 1
19: The two parts(A connects to A, B connects to be, etc
20: Connect them. This is your magazine you are finished with it!
21: The white near the pin should be situated like this on the blues
22: The greens should be squeezed together tightly here, adjust the duct tape if they arent.
Now time to build the handle
Step 4: Handle(or Lever)
Here is the lever used to reload and fire. It is a pretty simple part compared to the magazine
1: Build 2 of these, except on the second one, switch the direction that the blue and purple combo are facing
2: Build/get 2 of each of these
3. Attach the blue and gray combo, and four gray rods like this to one of the sides
4. Put the white in the grays like this for both ones
5: Attach those pieces to the back of the magazine like this
6: Attach the other side as well, here is you finished handle
Step 5: Stock
Here is the body of the crossbow
1: Build 2 of these
2: Build 3 of these
3: Connect them like this
4: Build this
5: Attach them like this, and add gray connectors
6: Add red rods and whites at the end of them
7: Build 2 of these
8: Connect them with 1 blue like this
9: Build this box
10: Connect them, so that both of the places with no blues are on top
11: Build this
12: Attach it like this
13: Attach it to the back part like this
14: Build this
15: Connect it like this to the other part, and add blues and whites
16: Build this
17: and this
18: and connect!
19: Build 2 of these (aren't you sick of seeing that)
20: connect like so
21: Connect that piece to the other like this
22: Connect everything together. Here is your stock!
Step 6: Bow
I am pretty sure that this is the first of its type of bow on instructables(correct me if i'm wrong) And i think it is one of the best, because it is very strong and can hold lots of force, and at the same time it is flexible as well, giving it extra power. I used this type of bow on my other regular crossbow, and that one can shoot about 200 feet. I would like to see it used more often.
Here are the steps:
1: Start by building the triangle in the center, it is 5 pieces thick.
2: On the bottom add this, its not necessary, i just have it, it can be replaced by a gray connector
3: On the right side of the bow, build this
4: Build this at the end of that part, as i said before, it is 5 thick
5: This is the end of the right side
6: Now the left side, it is the same, except it is opposite(That does make sense)
7: Here is the part after that
8: The end of it, same as the right side
9: What the bow should look like, the top view
10: On the bottom, gray connectors should be attached to the blues
11: Build 3 of these
12: Attach yellow rods to the center whites like this
13: Attach the red/blue combo like this, one on the top, 2 on the bottom
Now time to assemble everything!
Step 7: Assembly
1: Attach the bow here
2: The bottom should look like this, attach grey connectors here too
3: Two parts, stock and bow, and the handle and magazine
4: Attach the bottom of the handle here
5: Everything is connected!
Now time to string the bow
Step 8: Stringing the Bow
This will show you how to string the bow
1: You will need 2-4 approximately 7 in. circumferance rubberbands. I recommend just using 2 at first, it lets you make sure its working properly under less strain first.
2: You will need to attach them like this, start by putting the right rubberband under the left one, like this
3: Bring the one end over top of the other like the picture shows
4: Take the end you brought over top and bring it under the other like this
5: Pull the ends tight, it should look like this
6: Here are the rubber bands, You might only have one
7: I duct taped them together to make it easier.(only if you have 2) Notice that i did not duct tape the center which will touch the rod
8: Put one end around a small wheel and blue rod
9: Attach it on the one side of the bow like this
10-11: Take the other end and thread it through the magazine here
12-13: Bring it to the other side of the bow and put it around another small wheel and blue
14: Here is your strung bow
Step 9: Loading the Ammo and Firing
1: Here is the ammo, red rods, the coloring is off
2: Drop one horizontally in the magazine ( all these pics are taken from the right side)
3: It should rest like this on the rubber band. not quite on the track
4: Drop another one in, it should land at an angle, with the back resting on the orange, and the front resting on the rod below it, this keeps the firing one in place.
5: Drop the other rods in. I fill it to the point where the front edge is near the bottom of the orange
How to fire
6: This is the resting position, were you start, firing and reloading consists of two moves, moving the handle all the way forward, which loads it, and pulling it all the way back again, which fires. You can see why this would be a deadly weapon in ancient times.
7: Pushing the handle forward
8: All the way forward, it is loaded now
9: Pulling it back
10: About to fire. The pin will hit the oranges on the stock and push up, pushing the rubber band up and when it shoots forward, it will catch the rod and it will shoot out
Here is a video of it shooting correctly.
Step 10: Problems
This is a list of some problems that i have had, and how to fix them.
1: The rubber band wont go the whole way back when trying to load it. Most of the time this happens because it s catching the duct tape. Flatten out the tape a little bit and you should be good to go. Also, sometimes it just randomly decides not to, there is nothing you can do about that except to just keep going.
2: The firing pin won't push the rubberband up. This happens because it gets caught in between the greens most of the time. I've found that the best way to prevent that is after you load it, bring it back and fire it fairly fast.
3: It keeps firing nothing: This happens because the ammo can't fall properly onto the track. Sometimes it gets jammed. When it does that your best bet is just to empty the magazine and retry. The way to make it so that it gets jammed as little as possible is to make sure that the ammo is falling in the magazine right and the second ammo in line should have its back right on the orange connector right above the green rod.
If you need some piece replacements because you don't have enough of a certain kind, you can go to https://www.instructables.com/id/Knex-Piece-Substitutes/ for ideas. Thanks to hiyadudez for making it.