Thermite

[woodwalker]

I need to cut a piece of angle iron, but do not have a big saw, so I though " Why not use thermite? I have iron oxide and aluminum, and Ill use magnesium from a fire lighter to light it."

I got some iron oxide, put it in a pestle and mortar, and ground it up pretty fine. Then I got some aluminum and work hardened it, before filing it, then ground up the filings the best I could in the pestle and mortar. I then proceded to shave the magnesium off of the fire starter.

I decided to do a test run, so I got about an eighth of a teaspoon of both aluminum filings and iron oxide and mixed it together. I put the mixture on what I wanted to cut, and dumped the magnesium on top of it. I threw a match onto the magnesium, which burned, but the thermite never ignited.

Why didn't it work? Should I have measured the iron oxide and aluminum in terms of weight, not volume? Should I have mixed the magnesium in with the other two ingredients?

[eburgblue]

Thermite is some really cool stuff when used properly..... you could use a "shaped" dynamite or nitro or semtec too........ best advice...... quit screwing around with xxxx that's not meant for the job..... buy a torch or take it somewhere to get it cut safely. If you want to mess with things like Thermite please at least take a course in pyrotechnics or chemistry before you hurt yourself or someone else!

[Finnr]

Playing with thermite is an excellent way to wake up dead. Don't mess with it.
Finnr

[Ice Czar]

aluminothermic reactions are dangerous in and of themselves, they can be far more dangerous given a few uncontrolled variables.

But the blanket warning of "don't do that" around here is beginning to rub the wrong way. Are there better safer ways to cut that angle iron? Probably, but then he didnt mention how thick it is either. Would a thermite charge actually cut it completely? Hard to say, it will burnout what it hits more likely than not.


Is it better to feign ignorance and allow someone who is already actively trying to set off a thermite charge proceed by trial and error? Or should we explain the dangerous variables? I think that is a no brainer.

1. mix ratio, 2x > 3x oxide to aluminum very well mixed
2. preheated thermite can almost instantaneously burn, going off too fast to move to a safe distance
3. generally ignited by a strip of magnesium, not filings
4. flash burns and intense UV light dictate welding leathers, gantlets, and hood
5. anything that hot coming into contact with water or a damp material can flash heat to steam, with explosive effects
6. can vaporize toxic metals you do not want to breath
7. not an indoor activity, since it contains its own oxygen source and intense heat, its nigh on impossible to extinguish

I too would advise a more appropriate solution to cutting the steel
on the other hand, thermite welding, thermite foundry work, and blowing that safe at the Federal Reserve are more appropriate uses of thermite

[RainsFire]

try buying aluminum powder and red iron oxide at a paint shack.. that eliminates a few variables.. and ya, use a magnesium strip.. which I think you can get at a hobby shop? or I think somewhere that deals with magnesium roofing? I could be totally wrong but I heard somewhere about that..

[habu68]

Also check with local law enforcement, possession of a pyrotechnic device may be frowned upon.

Another thought, what is the chemical structure of spent thermite? At the reaction temps it would seem that all of the carbon would burn out leaving pure iron. I ask because I have access to the sprues left over from the welding of rail road track they are about 1 1/2 " thick and 10" long. and covered with the sand from the casting pot. I just wonder how they would forge.

[JohnW]

My high school chemistry teacher demostrated thermite for our class. She had a small amount in a paper cone in a tripod above a sand box. The flash was impressive, we could hardly get over it, but that didn't explain the laugher from the front on the class room. The thermite had no problem going through 2" of sand and the counter it was resting on, but finally stopped on the cement floor.

[habu68]

Another string on thermite:
Thermite welding

[matt87]

Originally Posted by habu68

I just wonder how they would forge.

Standard blacksmith's answer: get it hot and hit it! Can't realy hurt to try I guess, supposing you observe suitable safety precautions for working an unknown material (full face mask, good ventilation, bucket of sand etc.).

[keykeeper]

Originally Posted by habu68

Also check with local law enforcement, possession of a pyrotechnic device may be frowned upon.

You have that right, Habu.

Laws vary form state to state. In my state, our local fire dept. put on the annual 4th of July fireworks show. Any of us that wanted to help had to go to a "pyro" school, AND obtain proper licensing from the State, individually. Everyone who participated had to have a license. We even had to have an approved magazine to store the shells until the show, complete with multiple locking devices.

There are also laws governing the possession of pyrotechnic devices, depending on each devices respective class, as determined by state code. Sparklers, fountains, etc. are allowed to be possessed. Firecrackers, bottle rockets, etc. etc. are a no-no.

In these times we live in now, with Homeland Security and such, everything is suspect from the authorities, if brought to their attention. Even people who reload ammunition or shoot black powder firearms can become suspect if not careful as to what they obtain, the quantities obtained, HOW they use it, etc.

Better safe than sorry, IMHO.