Introduction: How to Make a Repeating Crossbow

This instructable will show you how to make a repeating crossbow, also called a "Zhuge nu" or "chu ko nu." This is a type of crossbow invented in China thousands of years ago that is like an ancient submachine gun. Just push the lever forward and back and it will fire a steady stream of arrows until the magazine is empty. It doesn't have that much power or accuracy compaired to a normal crossbow but it has a fast firing rate and is easy to use.

I have included an instructional video and a step-by-step photo instructable. If you have any questions or any of these instructions are unclear to you please let me know and I will try to clearify.


CONTESTS:
I think this instructable meets the requirements of the Epilog challenge and the Launch it! contest so I am entering it in those.



Step 1: Gather Materials

You will need:

-A 2x4 in any type of wood, prefer few defects of course (at least 27" long)
-1/2" Sch 40 PVC pipe (at least 22" long)
-Red oak 1x2 (53" or more, other hardwoods are OK)
-A 1/2" x 5.5" x 48" poplar board
-3/8" poplar dowels (recommend three 48" dowels)
-5/16" dowel (at least 10")
-Larger dowel, 3/4" to 1" diameter (at least 6" long)
-Glue
    -white glue
    -epoxy
    -hot glue stick
-String (I used 9/16" venetian blind chord, it is mixed polymers)
-Two 1/4-20 bolts, 3" long, with nuts.
-Wood screws (at least 6, ones that are 2"-3" long would be great)

OPTIONAL:
-Wood stain
-Spray on clear coat
-Brown spray paint
-1.5" wide hinge
-1.5" wide by 1/4" thick oak or poplar board (10")



All of that is available at a hardware store, mine was from Lowes mostly.

Step 2: Look at the Plans:

These pictures show all the dimensions and materials for the parts that need to be cut out and drilled. Mark these shapes onto your materials. Details about which material each part should be made from, hole sizes, etc, are written on the plans.

I don't think any more instruction is needed for this step unless the plans are unclear to you (they look fine to me but let me know if there is an issue).

Step 3: Cut the Parts

Once you have all your cuts and drill places marked, cut everything out. A band saw and a power drill (prefer a drill press) would be very helpful for this. Also cut the 3/8" dowels into 8" pieces. Aside from the sanding this is most of the "work" of this project.

Step 4: The Arrow Box

Get all the magazine parts (on the plans they are labeled magazine walls, magazine spacers, and arrow trough. For this step you will also need white glue, clamps (or weights), and idealy a dremmel tool or similar rotary sanding tool (but a round file, knife, or even coarse sand paper can work).

Sand the bottom edge of the front magazine spacer ("L" shaped one) so it is rounded concave. Then line up the magazine walls and spacers and glue them together (see pictures for position if it is not obvious to you). Clamp these together or stack weights on them while the glue dries. Once it is dry, sand it so all the layers line up smoothly without rough or uneven edges.

Then mark the lines shown in picture 6 on the arrow trough. There is one line going crossways on the board 12" back from the front (the end without the 1/4" hole is the front), and a line down the center from the front all the way back to the 12" line. Carve grooves along those lines with a dremmel sanding wheel. The front-to-back line is the trough the arrows ride in, and the side to side line is a notch that catches the bow string.

Glue the arrow trough on to the bottom of the magazine walls.

Cut or sand a 5/16 or 3/8" dowel in half lengthwise, so it is flat on one side. Cut about 10" of it and glue that 10" piece to the bottom of the arrow trough. Position it so it starts at the front edge of the arrow trough, is running lengthwise centered side to side.

Step 5: The Lever

This is very simple just glue and screw the lever handle on to the lever arms. White glue or epoxy are both good for this. I chose to round the other end of the lever arms for asthetics.

Step 6: The Stock

Once you have cut it out as shown on the plan, all you need to do to this part is grind a 14" long groove into the top like on the arrow trough. The dowel on the bottom of the magazine will ride in this groove that you grind into the stock. Then screw and epoxy the 6" long piece of 7/8" dowel on to the back of the stock.

Step 7: The Bow

Now you need the 22" long piece of 1/2" sch 40 pvc pipe with the markings on it as shown on the plans. We are going to heat it until it gets soft**  then press it between two 2x4 boards. 5/8" thick wood spacers should be placed between the 2x4s alongside the pvc pipe to control the final thickness of the pressed pipe. Use clamps to push the 2x4s firmly together.

Once you have done that squirt some hot glue into both ends of the pipe, this will be a filler. Heat the 3" long sections on both ends of the pipe (one at a time) and press them as shown in picture 6. The end of the pipe should be completely closed after this pressing. Be sure that when you press it the pipe is rotated so that the part that was wider from being pressed between the 2x4s is the part that becomes flat.

Heat the center 1.5" wide section of the pipe and bend the bow limbs (each half of the pipe) slightly back and upward.

Then cut / sand the now flattened limb tips into a roughly parabolic shape and smooth out the edges with sand paper. File a notch into the limb tips for the string to catch on (called knocks). Drill holes and screw the bow into the notch in the stock.

For the string, just tie a loop in each end and make it so it looks just on the long side of the right length. Tie knots in the string to shorten it one at a time. Keep putting it on the bow to check if it's tight.



**To heat the pipe I am using a propane heater but you can use a torch, a heat gun, an electric or gas stovetop, camp fire, bbq, etc. Try to move the pipe around a lot in the heat to keep from scorching it. It will become soft and flexible.

Step 8: The Ammo

Get your 8" long pieces of 3/8' dowel, they will be made into the bolts (arrows). Sand or file a  +  shaped notch into one end of each dowel. This will help the string catch it.

Then drill a hole in the other end of each one (drill press is much nicer for this than a hand drill). The exact size of the hole will depend on your arrow points. The arrow point is suppose to glue in to this hole. I used a 13/64" bit for mine. After you have the holes drilled epoxy in the arrow points. You may want to sand the area where dowel and point meet after gluing depending on how well the sizes match up.

Step 9: Finish

Assemble the completed parts and test it:

Set the magazine on the stock, slip the lever over that and line up the holes, and put the bolts through (you don't need to put on the nuts right now). Then string the bow and push the lever forward until it catches in the notch in the arrow trough. Pull the lever back. You will immediately notice that it does NOT fire. Don't worry I haven't mislead you. Let the lever forward and push the string out of the notch with your thumbs. Now all you need to do to finish the mechanism is to sand the front edges of the notch (the one the string catches in) to smooth and round it off. Keep doing the test with the lever until you get it sanded smooth enough to where it does fire. Now it's done!

At this point I chose to stain and clearcoat the wood parts and paint the bow brown. Obviously you can decorate yours however you want. After you have done whatever surface treatments you are going to do, it is a good idea to put vegitable oil on the center of the bow string to help it slide easier and not wear through as fast.

Comments

author
brian.griffin.31586526 made it! (author)2014-12-19

Thanks for the instructions on How to Build the repeating crossbow, I'm in the process of building the limb for this crossbow. The limbs for my bow are being made out of 3/4" schedule 40 PVC Pipe. The entire thing is built from Red Oak. On the left side of the bow I did a drawing of a Snow Leopard and on the other side, and don't think you can read it that well it says: "People should not be unfamiliar with strategy, Those who understand it will survive, Those who do not understand it will perish" Sun Tzu's Art of War.

Again thanks for the instructions on building this.

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author

Great work that looks beautiful!

author
StanleyK12 made it! (author)2016-08-05

I made it!

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author
propanehill (author)2016-02-21

Can somebody make this for me email at ttylbodydark@gmail.com

author
NoviceRick (author)2014-08-10

super cool. i played romance of the three kindoms, a historical chinese war game, and always wondered if repeating/auto crossbows were real. i didnt expect this.
I just had a thought, it wouldnt be too hard to put a trigger mechanism that can be disabled with a switch, then you can have auto shot mode or a trigger mode for when you want to shoot with acuracy.

author
jwgottabass (author)NoviceRick2014-10-05

There is a really cool commercially available one that re cocks itself with a CO2 paintball tank. It is expensive as hell but seems pretty wicked.

author
EmmettS1 (author)jwgottabass2015-10-14

What link is the site??? I want to make a Repeating Crossbow that re-cocks itself, is powerful, and accurate! Is it possible to put like a red dot light on the crossbow? Great Instructions!

author
Jaycub (author)NoviceRick2014-09-22

That would be cool and is definitely possible, I'm sure you can figure out a way to do it if you make one.

author
mr magic made it! (author)2015-06-07

I whipped this up with the kids on the weekend. Few things to tweak but goes pretty well. Great instructable.
My only headache was having to use imperial measurements, I thought Canada was metric?
Either way awesome. Thanks

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author
Jaycub (author)mr magic2015-06-08

Cool I always am happy to see someone making one! Looks like it came out good.

I am apologize about the measurements but I can't say I feel bad at all haha. Here in the USA I have to learn and use imperial and metric and have sets of tools for both in order to get my projects done. People say metric is "better" but it is just easier to think about at first because it is base 10, they are no different really.

author
cwees (author)2015-04-16

would it possible to make a larger/ more powerful crossbow for it? I have always wanted to make one of these

author
halfeatenham (author)2015-02-04

Is anyone else having an issue with the vidoes picture not working but getting sound?

author
lilchumy (author)2015-01-12

lol, that's the same band saw I have! I didn't think anyone else had that rinky dink thing. I got it at a yard sale a while back and don't know what size blade I need to put in it. any idea what size it is?

author
Jaycub (author)lilchumy2015-01-12

I think it takes a 56-7/8" blade.

Mine is gone now, YAY! (After the motor quit for like the 20th time and this time would not resurrect after a brush cleaning, and the bearings got super hot, I stopped using it and got a bigger one more suitable for my amount of use).

author
lilchumy (author)Jaycub2015-01-14

Congrats, I got mine at a yard sail for 15 bucks so I cant complain. I use it every day and it is just not big enough or powerful enough. Someday I will get a new one. One more question. Did you find that you could not make very good precise cuts with the half inch blade that came with it? Do you think a 1/8 inch blade would be better? (Nice prodject too by the way)

author
Jaycub (author)lilchumy2015-01-21

I don't remember which blade width I had... but yes it was hard to make precise cuts. It was better as long as I kept the plastic blade-guide pins (which eventually had to be replaced with wood dowels) in good shape.

author
tatebullrider (author)2014-12-02

I made this and it works great, and is really fun to shoot. would it still work ok with fletching? just wondering. awesome build btw :)

author
Jaycub (author)tatebullrider2014-12-31

It can work with fletching, you may need to change the design of the magazine to accommodate that though. Small soft feather fletching would probably be OK.

author
tatebullrider (author)Jaycub2015-01-11

ok, thanks keep up the good work.

author
JosephR3 (author)2014-12-20

thank you

will try to build one

Joseph Roberts

9810ST.RT.73

New VIENNA OHIO 45159

1-937-987-2526

fallsville@frontier .com

author
JosephR3 (author)2014-12-20

thank you

will try to build one

Joseph Roberts

9810ST.RT.73

New VIENNA OHIO 45159

1-937-987-2526

fallsville@frontier .com

author
jwgottabass (author)2014-10-05

1st of all, this is of course awesome so thanks for proving normal people can make one. But it looks heavy as all get out. Have you considered using other materials? Like I was just watching an Instructable on how to make your own kydex holsters and that stuff is super light, and seems fairly easy to work with, the bolt hopper on top made out of kydex seems like it would drop a couple pounds.

Thanks again for making this.

author
iFirefly (author)2014-09-16

What a beauty! Your video mentioned that we would find a link to the plans - in PDF I hope - but I don't see a file attached - except for the pro members.

Thanks!

author
Jaycub (author)iFirefly2014-09-22

The plans are the images in step 2.

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iFirefly (author)Jaycub2014-09-29

Thanks; my computer wasn't displaying all of the pictures.

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jsmit3 (author)2013-07-02

I would suggest making the bow out of wood it may be harder but its more powerful

author

it's more powerful if you use metal bar so it will be "repeating arbalest" instead of "repeating crossbow"

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Jaycub (author)jsmit32013-07-02

I used to use wood bows when i sold these as kits but it is easier to make it out of PVC and the statement that "its more powerful" is incorrect. This PVC bow is more powerful and smaller that the wood bows that were on the kits.

author
Jason the marksman (author)2014-03-16

Hard to make.but it's worth of it

author

Did you make it?

author
ubicity (author)2013-12-05

great stuff

author
paracordperson550 (author)2013-11-10

awesome

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jhowie103 (author)2013-10-15

Very impressed

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Ridach (author)2013-09-16

there is no measurements for the handle, or did I just miss it

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Jaycub (author)Ridach2013-09-16

It is there, in one of the lower pictures. You have to click on the images of the plans to enlarge them and you will find it in the image that shows "oak 1x2s."

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jsmit3 (author)2013-07-03

Also in the instruction it doesnt tell how to release the string

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Jaycub (author)jsmit32013-07-04

If you are talking about the thing that puches the string out of the notch, then you are saying things where you don't know what you are talking about again.

If you read the last step I describe how sanding the front edge of the notch will make the string slip off at the right time. I have made several of these things and the string-pushing block is realy not needed.

author
jsmit3 (author)2013-07-02

The bow part rather than pvc

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Big Baneser (author)2013-06-22

OMG!!! I saw a repeating crossbow in jack the giant slayer but it had two barrels and left me very confused

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antibobthebuilder (author)2013-06-18

COOL

author
Kid Ninja (author)2013-06-13

Just a note, the magazine walls are 18 inches long, not 15. Just a typo. :)

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Kid Ninja (author)Kid Ninja2013-06-13

Also, for the top half of the magazine walls, mine's not coming out to 14.5 inches. Is there an error?

author
Kid Ninja (author)Kid Ninja2013-06-13

Okay, as far as I can tell, the 9.5 inch measurement should actually be 12.5 inches, and the 14.5 inch measurement should be 17.5 inches. That allows the bottom and top edges to be the same size, and allows for the same angle on the spacer and the magazine walls.

author
Jaycub (author)Kid Ninja2013-06-13

I don't know how you are coming up with that. The angle is the same on the back spacer and on the back of the walls if you follow the plans. On the spacer and on the walss, the slant at the back goes down 3.5" and over to the right 5."

I did just find one error which might be the one throwing you off, the 12" for the part cut into the bottom of the magazine should be 9." Hope that helps. I will upload the corrected image.

author
Kid Ninja (author)Jaycub2013-06-13

Yep, that was it. The 12 inch measurement threw me off, and changed the angle of the wall. Thanks! Sorry to bother you.

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Jaycub (author)Kid Ninja2013-06-13

OK cool sorry about that!

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Jaycub (author)Kid Ninja2013-06-13

What do you mean? The will come out however you draw them. I don't think there is any error on the plans.

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Jaycub (author)Kid Ninja2013-06-13

No, they realy are 15."

author

very very cool. i saw one of these in museum once and tried to build one myself years ago. this is excellent work, i would however advise creating a quick diagram showing how it works so others can copy the mechanism with slightly differently sized or shaped parts. i am voting for it.

author

Thanks! That is a good idea to show the mechanism. Right now I'm thinking that it simple enough that they will understand just by looking at the pictures of the completed thing. But maybe I'll draw a diagram.

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