Bolt Firecracker




Introduction: Bolt Firecracker

About: just getting back into Instructables. Hopefully some better projects to come!

This is an extremely simple device for making a very loud explosive bang. It is very similar to a firecracker, but you can reuse it over and over. The material from the head of a matchstick is used as a propellant.

The only materials you need are two big steel bolts, one nut, and some wooden matches.

The basic idea is that the two bolts screw into each end of the nut, forming a small cavity between their ends. This cavity is filled with the ground up heads of matchsticks. When the device is dropped head-on onto the ground, the resulting compression creates enough heat to ignite the propellant and create a satisfying explosion.

WARNING: In most cases, the bolts stay together and nothing goes flying, but sometimes they can be released at dangerous speeds, liable to cause all kinds of damage (I, stupidly, had my lip ripped open by one of these bolts once). Use at your own risk with caution, safety and common sense.

Step 1: Materials

You can really use any kind of threaded matching nut and bolts for this device, but there are qualities that make some sizes better than others.

I have found that two 3/8 inch diameter bolts are pretty easy to find and work well for our purposes. The length of the bolts can vary from 1 inch to up to 4 or 5 inches. Longer bolts often work better as they allow the device to fall straighter and with a heavier blow. Thicker bolt might also give better results, as they allow room for more match heads.

The nut must fit easily onto the two bolts and their standard size is 3/8 inch in length. A longer nut might work better as it can provide more room for adjusting the locations of the two bolts, allowing both for more space in the cavity (more material, louder bang) and for more threads to engage (safer explosion).

Wooden matches work very well for this purpose because their ends pop off very easily and contain no wood. Strike-anywhere or normal kind both work, although the strike-anywhere are a little more sensitive.

Step 2: Assembly

Scrape off the tips of as many of the matches as you desire into a pile. It is usually good to start with the material from eight or so matches for one explosion.

Screw one of the bolts part of the way into the nut so a cup is formed. Put about three match tips in the cup at a time, screwing the other bolt on the top of the nut just enough to compress the tips into a rough powder. Then remove the bolt and add the rest of the tips incrementally. You can also crush the tips outside of the device and then add them at once.

Once all the match tips are added, screw on the top bolt as hard as possible with your hands. Be careful to not to use a wrench to exert too much force, as this might explode the device prematurely.

Step 3: Setting It Off

Now, find some hard surface and drop the device on the head of one of the bolts from about shoulder height. It may take a few drops before the phosphorous mixture is compressed well enough to reach a critical exploding temperature. The bolts will most likely loosen after each drop so remember to tighten them each time.

You can also try throwing the device up into the air to get a better compressive force, but in this case it may not land directly on the head of the bolt. You might try adding a streamer to one of the bolts to make sure it comes down vertically.

Reload and have fun!

Be the First to Share


    • Exercise Speed Challenge

      Exercise Speed Challenge
    • Pocket-Sized Speed Challenge

      Pocket-Sized Speed Challenge
    • Super-Size Speed Challenge

      Super-Size Speed Challenge

    7 Discussions


    11 months ago on Step 3

    It took awhile but eventually it exploded. WARNING- WEAR SAFETY GLASSES


    1 year ago

    Used to do this as a kid. Common sense is the key, drop it behind a wall or something.


    6 years ago on Introduction

    I'm going to give this Instructable a rating of dangerous. Seriously, I would advise against building or using this device. That said, if you can't be dissuaded, maybe use a rod coupling nut? The additional length might reduce the likelihood of a bolt breaking free and and injuring you.

    I've heard of people doing this with the oversized bolts used in bridge construction, then getting killed. It would be a good idea to stay as far away as possible, and probably wear some polycarbonate shooting glasses, or a paintball mask when trying this instructable. Don't try the bridge bolts, you or someone else will get killed, whether the bolt is shooting up or falling down.


    10 years ago on Step 3

    ATTENTION!!! I don't suggest you to do that like in the last photo.. bolts might fly back in to you.. you better take some solid pipe  so those bolts would  slide in it down and fly in the direction that you could target for safety.. My uncle used to do that when he was a kid. He have been throwing it while hiding behind some wall so he could hide himself when bolts explode, or he was using a pipe as I have mentioned... He might be used more match stick heads for this, but you never know when BOOM will be bigger or smaller.. so Be careful.


    10 years ago on Introduction

    Fun times - I used stacks of paper cap gun caps (2-20 caps) If you're worried about the explosive force, then you could chain the 2 ends together by welding a length of chan to the bolts, or using 4 extra nuts to make a lock nut on each end holding the chain on. Good times.