How does thermite work for casting? I figure if it can weld heavy section iron seamlessly, then it would get plenty hot enough to say, put ontop of a prepared mold with a melt door, then fire it off to fill the mold, no furnace needed.

I'm staying away from you.

AW Bob, that's no way to be. I understand your'e a little ill because of the cat thing......but never had any dealings with thermite so I would at least stand a LONG ways away

I've also given thought to possibly making small castings using thermite, but you'd have to be VERY carefull not to let any pressure build up inside your molds, or things could get ugly exciting real quick. (As in molten hot liquid iron drops, droplets and blobs flying everywhere.)

As to the thermite itself, I suspect that both availability and price might be becoming an issue what with just how tetchy folks have become over the availability of things that will go boom.

I remember growing up you could buy a jar of saltpeter at any drug store for a quarter. Even far less than that long ago a 50 lb. sack of amonium nitrate fertilizer was on sale at a home base for $1.75... and PLEASE buy all you wanted. Nowadays some places make you sign to buy a box of 50 match books. Heck I just had to go through a 66 day review to determine if I was American enough to accept custody of two 6500 watt diesel generators just because they happened to be painted OD green. (bought surplus from Hill Field in Utah)... and I once held a NATO Secret clearance but it still took 66 days.
Not sure I'd be up to the hastles involved in buying thermite. Of course I could just grind up a bunch of old iron and aluminum and mix up my own. Or mix urine and dung with wood ash, precipitate out the salt peter, mix with sulpher and charcoal...

Doc

OK Bob, I'm gonna stay way from Doc!

Thermite casting is essentially what they do with railroad rails to weld the ends together (except in that case they preheat the rail with torches for a better weld).

I'm not real clear on how it's done, but I know you don't want the thermite in the mold itself. You have to ignite the thermite in a crucible and then let it pour into the mold.

You could buy the chemicals you needed from a site like skylighter.com. They do require a picture of your driver's license but that's all the hassle they'd give you.

40 years ago,I used to ride my Schwinn (with the banana seat and ape hangers) ten miles into town to buy sulfur and saltpeter at the Walgreens. Got the charcoal from the fireplace.

You weren't alone Doc. Our 1950's weekend activities almost always included the saltpeter and sulphur or matcheads, fuses and pipes. Although we never bothered with one, a blasting permit was 25 cents at the town clerk and all supplies could be had at the general or hardware store.
Nowadays, we might wind up in the hoosegow for just reminiscing about it.

I'm unconcerned about the possibility of that (ending up in the hoosegow for reminicing). I'm not an anarchist. I'm most definately not a terrorist. My point in mentioning just how simple it would be to mix up a batch of black powder was that you really can't put the genie back in the bottle. If simply knowing how to make things that will go boom was suffient enough reason to put someone in jail, then they'd have to round up every student who took a first year chemistry class in college... or even high school. Heck, I was actually in junior high when I first learned about what saltpeter would do just mixed with a little plain sugar. But just knowing that, I never attempted or even felt the slightest desire to ever try to hurt anybody with that knowledge. Freedom at the cost of innocent blood isn't freedom.
Doc

I did my share of those "experiments" back in the day 35 years ago. Of course back then I could out run trouble, stop bullets with my chest and jump over buildings. I'm too slow now and splat
instead of bounce. Did my share of EOD work with Uncle Sam so you start playing with that homebrew stuff I'll watch from a friendly distance. I'm amazed I lived through high school!:)
Don't mean to say you are some kind of wild eyed radical goofball like some guys that dislike politicans around here, . The problem is proving that you aren't one of whoever they are looking for!
In theory, it should work, if you only had one or two parts to cast. Would it be easier to determine the amount of metal for a pour? Wouldn't have to worry with oxidation, the slag would shield the metal. Hmmmm.....There's got to be some reason they don't do it that way......what the heck Doc, if I was anywhere near Utah I'd give ya a hand and see how it works. It's crazy enough it just might!

According to a friend who is more knowledgable on the subject, one of the major problems is that the thermite itself is still burning and creating major gas outflow long after it would melt through a metal plug and flow down into a mold, so basically you almost can't use any closed cavity type molds with it (or it will like blow up!). If you look around for an Extreme Engineering program on building the super stadium for the Arizona Cardinals, they show a thermite welding process used to weld railroad rail sections together. (used to support rolling lawn design). It shows how their batches were carefully planned to us just enough for the aluminum oxide waste slag to bubble out into side catcher trays after the iron flowed down into the ceramic clamp on molds backed up by casting sand and firebrick.
Cool to watch. Another cool to watch show was when the Mythbuster guys cut an SUV in half using 1000 lbs of thermite.
Doc

Hmm, true that outgassing could be a problem. As for buying it, it can be picked up in you-mix packages from a couple of online chem supply places, because it doesnt go boom, it just burns hella hot. As far as people wanting to stay far away from me, I really don't have a problem with that.

AW, c'mon TEOC. Think of how much fun we could have if you got all of us together! I know your'e just being nice,what you really meant was "wild eyed, radical, polititian hating, ex-military goofballs".:) People was just shorter, right?:) Hey, if you think I'm bad, you aught to hear the conversation on Harleys from Bobodu on the old site. Gang, I'm the one who likes to set mag on fire just so I can show everbody else how it will burn down into the ground and is nearly impossible to put out. TEOC I still like the way you think. I wish I had you around when I was converting those looms over. All I could get from my crowd was "that ain't never been done before" or "they tried that 20 years ago and it didn't work". I like someone that thinks outside the box.....keep it up, it makes the rest of us think.

1. ANYTHING that creates or converts into a large quantity of gas will go boom if it is confined enough... e.g. dry ice in a soda bottle; big enough boom to destroy a residential mailbox.
2.Me: Wild eyed; yes. Radical? Not really, but definately non-conformist. Polititian hating? What's not to hate?. Ex-military? Sorry, was 4-F medical. Goofball? Uh...fun loving.
3. Bobodu and Harleys.... I'm definately going back to bed.
Doc

Hm...
Wild eyed? - depends on how much ive had to drink
Radical? - Against a fair and honest, limited government, not at all... against our current government, well thats another story.
Politician hating? - Lol, im southern, that's all I'll say there.
Ex military? - sorry, gunna be a no there. Im only 23 (24 on the 15th) and I doubt they'd take me even if I wanted to go (bad ears, bad eyes, flat feet, bum leg, etc, etc.)
Goofball? - definately
The comment about people wanting to stay away from me wasn't meant to be derisive in any way, it just doesn't bother me either way. I gave up worrying about what other people think of me, there's always someone who's interested and can either teach me or learn some of the very little i may have to teach.

As for the out of the box thinking, I figure the box contains too many people, and since I don't like crowds i stay away from it. That and watching my robots go back and forth for eight hours at work gives me time to think.

Sounds like your'e a rolling wreck like me. At least that's what the guys at the plant called me. VA says I'm 51 stuck in an 81 year old body. I'm with you on the crowds...too many people. Uncle Sam taught me how to do my thing solo or with a team, I'd rather be alone when building something, I don't have to explain what I'm doing.If you ever get up this way, stop in , we'll crack open a new box of rods and make something!
Terry

I'm not much for travel. I like keeping feet/wheels whatever on the ground or on the water. Them there aeroplanes are too mechanically dependant for me to ride in. Lol, think about it, your car goes dead... well you pull over and call a tow. Your boat motor dies... you pull out the paddle. The engine in your cessna dies, you glide down to what's probably going to be a rather painful landing... Power in your 747 goes... start praying and hope you're right with the lord. And I'd probably freak if a guy with a long beard started singing or something. (no offense to anyone intended.) Now if i were ever DRIVING that way then I'm always up for burning some rods! I would say you're welcome here too, but I'd probably be asleep or at my 3-11 making those sawzall blades we all use so much. (REAL Millwaukee sawzall, not that B&D crap.) Though you could always kick me a few times or blow welding smoke in my face to get me up.

P.S. - My body is probably pushing 63 Oh well, if I'm really 63 then that means I can eat all the cake I want for my birthday tommorow.... at work...

What is this sawzall thingie?
Is that some kind of TORCH?


(My recip sits on the shelf....).

Just as handy as the torch as long as you have a good blade. Keep on making them TEOC. They are too hard for me to hold onto nowadays, my thumbs won't bend to hang onto the thing. I always said my next big tool purchase would be a porta-band. Instead Big Ugly followed me home. Porta-band would have been less work!

Actually works better on wood... you don't have to keep blowing the flames out.
Doc