Automatic Blowpipe

Introduction: Automatic Blowpipe

The blowpipe made of a pen body or a drinking straw is a very common school and office weapon because it is very easy to make.

It can deliver high-speed spitballs over distances up to 15 meters (16.4 yards) (depending on the type of projectile that is used and the blowing technique)
It also has good accuracy (depending on the length of the "barrel" and the type of projectile used).

But most of the battles occur at close range, where you do not need the big range and you also don't need high accuracy. In close-range battles you need something that would shoot a maximum amount of spitballs in a minimum time.

And that is what I want to teach you to make.

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Step 1: Supplies

you'll need:
1.drinking straws or pens, the outer surface of the pens should be without facets and their internal diameter should be the same. (you'll need a piece of straw anyway.)

2.small scissors and x-acto or paper knife for the straws, drill for the pens (if you have some skill you can use an X-acto knife instead of the drill)

3.CD-pen (you can use anything that could write on plastic and is permanent)

4.hacksaw for the pens(again, an x-acto knife and some skill will do the job, too.)

5.super glue or glue gun(the straws dont like hot glue 'cause it's hot)

Step 2: Cut the Pens

1. disassemble the pens(if you use straws, skip this part)
2. cut off the narrow part of the pen

Step 3: Make Fishmouth Cut

make a half-circle (fish mouth) cut on one end of one of the straws, if you use pens, try to drill it or to cut it out with x-acto knife.

Now press the straw/pen with the cut to the other straw/pen as shown on picture and check if it fits together. if it doesn't, correct the shape of the cut a little bit and check again.
Do this until they fit (almost) ideally (if you use hot glue you don't need much accuracy.)

Step 4: Cut Some More...

Press the feeder straw(the one with the fish-mouth cut)against the other straw and outline the feeder as shown on picture.(if you use pens and a drill skip this)

Now cut the orther straw/pen by the line If you use a knife(picture 2),
Or drill a hole of the same diameter as the inner diameter of the pens if you use a drill.

You should have a cut as shown on picture 3.

Step 5: GLUE IT!

Now put the feeder straw into the cut on the barrel as shown on the layout.
Remember to leave a slit because cutting it after gluing could be very hard and annoying .
Then glue it!

Step 6: Make Semi-auto Mechanism(lock)

First, take a small piece of straw and cut as shown on pictures 1 and 2.
you should have the shape as on pictures 3 and 4
put it on the barrel and slide it into the slit you have left as shown on pictures 5, 6, 7, 8 and 9.

Step 7: Make Additional Clips (only for Straws, Optional)

First, cut the feeder straw about 1,5 cm (1/2inch) from the barrel.
then make the end of the feeder a little wider with a pen tip(picture 2)

Now cut the straw(s) into clips of any length.
I use the 1/2 strawlength clip (the big one) for continuous automatic fire because of its high capacity - (the automatic blowpipe can fire about 5-10 shots per second)
and the 1/6 strawlength one for semi-automatic fire, stealth firing and storage in loaded position because of its small size.

Step 8: Make Some Caps (it's Optional, Too But Do It If You Make Multiple Clips)

The caps stop air from escaping through the feeder and clip and help you to store loaded clips by stopping the ammo from falling out.

So, to make the caps, take some wet toilet paper or wet tissue, or some clay etc and make a ball with a diameter that is about 1.5 times bigger than the straw/pen diameter(see picture 3)

Now press the ball into the end of the straw or pen and take it out saving its shape and let it dry.
It should look like the one shown on the picture.

If you make multiple clips, make 2 caps for each clip and 4-5 spare caps to replace lost ones, because you WILL lose them in battles.

Then check that the caps sit tight and make new ones if they don't.

Step 9: The Ammo

There are multiple types of spitballs.
But you can describe it with three words(or three digits).

the first says whether it is dry or wet.     (wet=1, dry=0)

the second says its hardness. (extremely soft=0, soft=1, hard=2)

the third says the shape    (spherical=0, ellipsoid=1, cylindrical=2, no shape=3, divided=4)

the only one that is suitable for the Automatic Blowpipe is the Dry, Hard&Spherical (or 020) one.

making ammo for the Automatic Blowpipe is the most annoying part, because you'll have either to make very much ammo or to make its diameter and shape almost ideal.

If you have found some pens with 6 mm internal diameter, congratulations! you are lucky and don't have to make the ammo, because bb's are 6 mm.

But there is a very small chance that you could find 6-mm straws and most pens are not 6 mm in diameter too, so you should make ammo yourself.

First, the ammo should be dry and not sticky, because it has to go down the feeder/clip with its weght only and if it sticks to the wall of the clip or feeder, it won't come down.
Also, it should be an almost ideal sphere because when it comes down, it rolls and if it's not a ball it will stop rolling and won't come down, too.
Next, its diameter should be smaller than the pen/straw's internal diameter but not smaller than 1 mm less than the pen/straw's internal diameter(shown on picture.)
And finally, it should be hard (why it has to, is shown on picture 2.)

Step 10: Shooting

So, normal operation (semi-auto) should look like this:

1a.If you use multiple clips, take a clip and take one cap off. Then you insert the uncapped side into the feeder(the lock is "closed"(see picture 1))

1b. If you don't use clips, just load ammo into feeder and put a cap on it or cover the end of the feeder with your finger unless you want a fountain of ammo out of the feeder. the lock and let one round fall down(picture 2)

3.close the lock and blow!!!(picture3)

repeat substeps 2&3 until you use up all your ammo, then take the clip out, recap it and proceed to substep 1.

For automatic firing mode, just leave the lock open and blow, blow, blow...
1 to 6 seconds - and the ammo's gone!

For condition of operational readiness(storage of weapon with ammo loaded and clip attached, ready to fire) do substep 1, and leave the lock closed(if it's open,the ammo could just roll out through the barrel)

Step 11: Blow Correctly

To increase range and accuracy, you have to increase the projectile speed.
To give the projectile more speed, you have to either increase the tine you blow onto it or you can create more pressure in a smaller amount of time.
You can increase the time you blow on it by increasing the barrel length.
And to create more pressure you use blowing techniques.
And I want to teach you one of them.

This technique was taken from pneumatic guns.
In a pneumatic gun of any type (except the piston ones) air pressure is built up in an external tank, then the valve opens... and bye-bye projectile!

This blowing technique makes us do exactly the same thing.
The mouth serves as the external tank, the blowpipe as the barrel...
And where's the valve?
It's the tongue!

So that's the technique:
shut the end of the blowpipe with your tongue,
build up some pressure in your mouth
open the end of the blowpipe and watch the projectile fly!!!

Also, please rate and comment.

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    13 Discussions


    8 years ago on Step 5

    why you have to leave a slit?


    Reply 7 years ago on Introduction

    to let the 'lock' element slide into the feeder and obstruct it, so that no rounds fall in the barrel and no air escapes

    it isnt working for me now matter how hard i try. i try doing it but it isnt working.... Rating: 7/10- Good


    9 years ago on Step 7

    Maybe make a more durable one with bic pens?


    Reply 9 years ago on Step 7

    уоu would have to have a lathe to shape the clips and the feeder if you want to make them from pens.


    10 years ago on Introduction

    great instructables I've been making these for sometime but whenever I blow the ammo comes out of the clip. but i think it may work now. Also I use the tongue method!! Yay!! I'm not the only one.

    Captain Dyson
    Captain Dyson

    10 years ago on Introduction

    firstly don't say not to critisise otherwise people will just to annoy u but this is a great Instructable and I will make it when I find something with a good size barrel


    10 years ago on Introduction

    This is really cool! Most blowgun instructables that use straws suck but not this one! 4.5/5 stars!