How To Make An Electrical Arc Furnace
How to hack flashlight batteries and a fire brick, into a desktop arc reaction chamber. ...For hobby metal melting, and for science!
Project Inspired By:
This project was originally inspired by Theo Grey and his book, "Mad Science". After seeing the concept, I couldn't find any information anywhere on the internet or in libraries about arc furnace experiments, so I set out on my own to achieve these results.
WARNING:
Risk of electric shock, fire hazards, and toxic fumes depending on what material you're working with. Dust from refractory brick should never be inhaled, as it can damage lungs and cause long term respiratory challenges. This project can reach temperatures in excess of 3,000ºF (1,648ºC) which is well beyond the melting point of hobbyists. Caution, care and expert planning are required to mitigate risks. Have fun, but always think ahead, and remember that every project you try is at your own risk.
Project History & More Info:
If you're wondering where you can get fire brick locally, try a quick Google search for “refractory materials” in your city. I called a couple of companies near me and asked if they'd sell to the general public. All of them said yes.
If you can't find anything locally, try searching major hardwares stores online. They usually have inventory online that they don't carry in the stores.
The insulating fire bricks I got were the 3” x 4.5” x 9” Alumina-Silicate Brick variety. I got a box of 10 for $33, effectively making them around $3.30 each. I went one step further and designed the furnace so that 2 of them could be made from one brick, cutting the cost in half, making each furnace a pro-rated $1.65 each!
They're extremely lightweight, and capable of withstanding the temperatures used in steel working, but soft enough you can cut and carve them with kitchen utensils if you need to.
In reading and studying history a bit, I learned that some of the earliest forms of light were made using carbon arc lighting. Large amounts of electricity were pumped through carbon rods, making a bright arc and providing light.
To scavenge carbon electrodes, I took a lesson from NurdRage (youtube.com/NurdRage) a couple of years ago I saw his video on what could be scavenged from a carbon-zinc lantern battery (http://bit.ly/IBNurdRageBattery). It's useful to know what common everyday materials are made of, and these heavy duty batteries are containers packed with carbon rods, zinc metal, and manganese dioxide. I tucked the information in the back of my mind until now.
In this project I tried melting the zinc casings from the lantern batteries, and casting them into a small ingot, formed with a mini muffin tray. Be cautious of the zinc oxide fumes produced. I haven't personally suffered any ill effects from working with it, but some people claim it can give flu like symptoms, or a fever if inhaled in large quantities.
Zinc has a relatively low melting point 787.2°F (419.5°C), so the Arc Furnace is able to melt each casing into liquid zinc in around 5-10 seconds. That's amazing!
I don't have an exact purpose for the zinc yet, but it's an easy metal to work with, easy to cast, and great to have on hand for a future projects. It's also one of the main metals used for making a simple carbon-zinc battery.
The black stuff pulled out of the battery casings is manganese dioxide. It's a useful chemical for experiments with hydrogen peroxide, so it's worth hanging onto.
Although I haven't verified it, I believe any stick welder can be used to power the mini arc furnace, and for most hobbyists, that would definitely be the easier and safer way to go. I just don't own a welder, so I used the one I made instead. You can see how to make it here: http://bit.ly/ARCWelder
The longest I've run the unit continuously is around 3-4 minutes, and the electrodes get so hot at that point they can seriously burn your hands, or melt your gloves. I wouldn't recommend running it any longer than that.
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