I enjoy fire. It's exciting and vibrant, with and ever-present danger that makes it that much more fun. There's nothing quite like being able to hold fire in your hand, or shoot fire from your hands for that matter. This is my third project on that quest to control fire.
This is THE perfect addition to your Pyro from X-men costume, or Zuko from Avatar the Last Airbender! What's better yet? Both of them walk the line between hero and villain!
*Note: Though this project is titled as a "flamethrower", it is not intended to be used as a weapon in any fashion. This device is meant as a prop, or pyrotechnic display device. Playing with fire can be dangerous, and only experienced people willing to take all necessary safety precautions should attempt a project such as the one described here. Be smart and safe, because by reading this article, you claim full and complete responsibility for any use or misuse of the information presented here. This article has been written for informational purposes only.
**Additional Note 12/27/15: This project was written a long time ago, and ended up in my drafts. At this point I'm confident that I'm done progressing this particular model of flamethrower, and so I feel comfortable hitting "publish", although it is not as detailed and beautiful as I originally intended.
Step 1: Video!
Step 2: Design
I am pretty proud of how I designed this device. It went through a few different drawings and prototypes and significant changes were made. However, I ended up with an extremely Simple, Small, and relatively Safe design that functions very well. Thus I've called this model, the "S3". It has only one moving part, and once all the parts are cut, is assembled using only adhesives, and a few screws.
The primary goal of the design was to make a flamethrower that only had parts of my hand. My wrist, belt, etc. were off limits. I wanted this to be the small, portable, close-range model of homemade personal flamethrower family.
To accomplish this, I originally wanted to put the functional parts of the flamethrower, levers and fuel, on the back of my hand, leaving only the burner on my palm. This ended up being difficult to cut the pieces to make by hand because the design I had come up with had very small parts involved. The plexiglass that I used to make the pieces ended up not being quite strong enough for the idea I had in mind, even at different thicknesses.
I've attached some pictures of my first couple designs, and attempts at making those designs, as well as screenshots of the final design from TinkerCAD. After I had modeled the device in TinkerCAD, I was able to export the pieces as an SVG file, and print stencils to cut the pieces I needed.
Design files are available on Thingiverse here:
Step 3: Plastic
The body of our flamethrower will be made out of plexiglass, also called acrylic sheet. This is 1/8", or roughly 3mm in thickness. As mentioned previously, the device was modeled using TinkerCAD, then each piece was laid out to be exported as an SVG vector file. If you don't know what that is, basically what TinkerCAD can do is take the 3D model that was made, and export a 2D drawing of an outline of all of our parts.
That outline can be printed onto paper. The pieces are then cut out with scissors and taped to our sheet of plexiglass. Those pieces are then cut out using my NiChrome VoCutter (read my Instructable on that HERE). I chose to cut some of the small holes using my Dremel with a 1/8" milling bit instead of my NiChrome cutter. The pieces are finished by shaping and sanding with a Dremel rotary tool and sand paper.
Step 4: Assembling the Base
Now that all the pieces have been cut and sanded, they can be assembled.
Part of the design goal for this project was easily assembly, in case at some point I wanted to create kits for this project. The base is entirely assembled with Super Glue. Base on the 3D model, is should be fairly apparent where each piece goes.
Because not all of my pieces were cut perfectly, some holes needed to be filled in for optimal strength. Super Glue and Baking Soda make an awesome filler. Simply apply super glue to the joint, and sprinkle some baking soda on top of it. The super glue will set up instantly, and excess baking soda can be brushed off. The join can then be sanded smooth.
Step 5: Burner
The Burner is made mainly using two different sizes of copper tubing end caps: 1/2" and 7/8". A hole was drilled in the center of the each cap.
The larger cap received a roughly 3/8" hole which our flames will come out of. The smaller received a 1/8" hole that will be used to screw the burner to our base, and help to compress the gas coming out of the burner for larger flames. Multiple small holes were also drilled into the side of the smaller cap.
JB Weld was used to connect the two end caps together, by spreading JB Weld onto the top edge of the smaller cap, and placing it inside the larger cap. JB Weld was also placed in a thin layer on the bottom of the smaller cap to act as a layer of insulation. This can be considered optional, as it wasn't completely necessary when everything was put together.
This will create a sort of heat exchanger. That way, the cold expanding butane fuel will enter the burner in the outer shell before entering the inner shell where it will ignite. This helps keep the outside of the burner at an appropriate temperature to prevent burns from stray fingers, and to vaporize the butane as much as possible. This prevents burns from liquid butane splashing out of the burner onto the user's hand.
Step 6: Connections
Butane needs to be able to move from the 2oz butane canister to our burner. This means that the built-in valve needs to be pushed, and the gas needs a pipe or tube to reliably move to our burner with no leaks. Ideally, canisters would also be easily exchangeable.
Two pieces of plexiglass were cut, and a small section around the center hole was milled out using a Dremel rotary tool. This depression in the plastic will hold a small #8 o-ring. The two pieces of plastic are able to be screwed together. This applies pressure to the o-ring and helps keep everything secure. I ended up applying super glue in between the layers of plastic just to be sure no gas would leak out. The plastic also allows the butane to be released, as the canister is pressed against it to open the built-in valve.
A piece of 1/8" inner diameter brass tubing was bent into a "U"-shape to transport the fuel from the plastic pieces to the burner. This was JB-welded in place at both ends.
The Burner can be screwed into place on the top of our base at this point, and JB Weld can be used to seal the edges completely.
Step 7: Finishing Steps
A small section of a 100% Cotton hand towel was cut and stuffed into the smaller end-cap of our burner. This will act as the wick for our pilot light. 100% Cotton is an important feature of our wick. Synthetic fibers will melt, burn, and create problems. The wick is used by pouring a small amount of denatured alcohol into the burner. The alcohol is absorbed by the wick, but the vapors given off can still be ignited.
A Velcro cable tie is used to secure the device to the user's hand by threading it through the holes in the base. The device can then be worn bare-handed, or with any glove of the user's choice for some added protection.
Step 8: Conclusion
Thank you for reading! I'd like to remind you again to be safe and smart if you chose to recreate this project. Fire is only fun if it is used in a way that nobody is hurt. Also, based on my what I've experienced in building this device and other similar ones, this is not a practical weapon. You are far more likely to hurt yourself by using this device than anyone or anything else. As a prop and pyrotechnic display device however, it's pretty fun.
Leave a comment! I mean if you feel like it. Nobody is forcing you, but I like them.