im sure a lot of you have seen this video where grant thompson makes a mini metal foundry and uses it to melt aluminum soda cans to cast small props or items
i wanted to get an extra oppinion if the way he builds it is safe enough for the average person
i primarily want to use it to make small costume props for myself and wanted to see what all of your opinions are on it or if there are better diy guides you know of
holy shit... I have a free weekend starting after 5pm tomorrow... a paycheck coming in... and a wife who has 3 12 hour midnight shifts coming up starting tomorrow... fuck it I'm giving this a try...
Don't bother trying to melt aluminium cans. the metal in them is terrible and soft + shrinks alot more than aluminum designed for casting, and theyre so thin that they burn before they can melt.
i hear the trick to getting them to melt is to crush them down and then push them under a puddle of already molten aluminium, which causes problems with any water left in the cans potentially flash boiling and spraying the molten metal all over. and on top of that you'll still get alot of dross to clean out
you're best off finding things that are already made out of cast aluminium and melting them. old hard drive cases are a good source of high quality aluminium if you can get ahold of them
also if you are going to cast id recommend looking up stuff on safety. theres alot of risks that might not be so obvious. like i found out once that if a crucible fails and dumps molten metal onto a concrete floor, the water in the concrete boils and causes the concrete to chip off and fling bits of the metal with it. its recommended to pour some sand around where you're planning to carry the crucible
i've also seen graphic pictures of what happens when a crucible fails and dumps the metal onto somebody's feet. the person was wearing trainers, the metal melted right through the plastic top, and got trapped in there with the feet
also worth mentioning that I grew up with a dad who worked as an industrial engineer and have heard enough horror stories about what metal does when it gets free to have a VERY healthy respect for the dangers involved in this... and plan on taking the actual melting process very slow...
got a nice patch of dirt backyard that I plan to try this in once I finish the foundry.
its pretty safe if you dont let it get too hot. however...
>do not use anything that is galvanized
i cant stress this enough. goes for welding, casting, smithing, etc
that threaded tube he used for the blower tube...try to find black iron pipe that is similar. galvanized steel tubing exposed to that level of heat will produce extremely toxic fumes and can cause "metal fume fever" which is a serious condition with serious symptoms
>plaster and sand refractory
i think this is a last resort option. there are other cost effective, better performing, and longer lasting refractories that can be diy. I would imagine this plaster and sand mix would begin to decompose pretty quickly....however, it could be patched easily
check out backyardmetalcasting dot com and instructables for other tips
have fun and invest in some welding gloves and tongs.
Yes, it is quite safe. Just take normal fire prevention steps, don't fall on it, and don't spill hot metal somewhere it shouldn't be spilled. Metal casting is super easy. If you make ingots, Always heat up the form with a blow torch seconds before you pour into it; if it is metal. Or, there can be an explosion.
I've melted quite a few soda cans. The metal in them is fine to use. HDDs are nice though. They are easy to break up with a hammer and toss in. but, I find that I have to pout the metal through some hardware cloth to stop and hidden parts of metal in the HDDs that isn't aluminum. Some have weird things in them.
I always make ingots before making a casting.
Galvanized stuff is fine, just don't breath the fumes. Not that you should ever be breathing the fumes at any point during forging or metal casting.
I agree with the plaster-based refractory. But, it is cheap and temps for aluminum are pretty low. It'd be great with lead and zinc too.
Only thing bad about his channel is the kid-like voice.
He's legit in how it's done properly with the tests.
Also safety/telling metals apart.
(cans are soft and meant for other purposes than a solid object, like holding a flexible pressure as a container etc)
The Grant Thompson version is interesting in a "throw things together" way. It's kind of neat to see that plaster of paris and play sand actually works, at least for a little while, as a castable refractory.
But on the other hand, it's just not that hard to get stuff like fireclay, from pottery supply stores. And he does understate the costs of doing things. Like buying the minimum available quantities of things, and then dividing the cost by how many of the same thing you can make, when people would not normally want multiples. Or not counting the cost of various uncommon items, like his wide, shallow bucket that's just the right size or his empty fire extinguisher, and tools that not everyone would have laying around, like his hole saws.
He says you can make it for less than $20 just by following his instructions, but realistically, it's probably going to end up costing over $200 and you're probably going to have to get creative to make it work.
If you read the details, he tried many times before he got these results, then he barely used the final version before posting his video.
I take Grant Thompson's stuff more as motivational material and inspiration than serious how-to. He makes things feel within reach, and if you stretch a little farther, you can do things a lot better. It's because of him that I'm thinking of building my own quartz tube multi-chamber furnace for home semiconductor production.
I can't see plaster lasting that long.
Look up Ceramic Fibre Wool (the high temp stuff not the loft insulation stuff). That's amazing stuff, weights nothing, reflects light and heat making your furnace much more fuel efficient and it is ridiculously temperature resistant.
If you wanted to do it really cheap you can just use ordinary clay dug out of the ground as a refractory (clay not dirt). Just do the same as the video but replace the plastic bucket part with a steel bucket compact clay around it tightly and leave it in. Also you have to put the pipe in first.
The steel bucket in the centre will eventually burn off, but by then the clay will be as hard as brick and clinkers will maintain the inner chambers shape. Keep it dry and it'll last, pic related my clay furnace melting brass at over 1000 c, used it for three years, still fine.
i was talking with a buddy of mine at work about this and he said using a propane burner as a heat source could also be an option depending on how/what i build the final product out of.
I prefer hardwood lump charcoal myself as it is readily available and doesn't require anything special to hook up.
Here are some pros and cons if you are interested though:
Also check out the rest of the website for other furnace designs. It helped me build my first one (pic related).