How To Make The Mini Metal Foundry

How To Make The Mini Metal Foundry

Things aren’t always what they might appear
to be. For example, this decorative houseplant you’re looking at, is actually an artfully
disguised, metal melting furnace. In this project we’re using equal parts of sand
and plaster, to make a simple backyard foundry, that’s powerful enough to melt scrap metal
in seconds, but still pleasant enough keep around for decoration. Let’s start this project with a big bag
of play sand, and some plaster of paris. Both of which you can find at your local hardware
store, for under $20. We’re also gonna need a 10 quart steel bucket, and a tablecloth
to cover anything important, because chances are this is going to get a bit messy. I found
that this 2.5 quart bucket can be used for measuring the ingredients, but it’ll also
serves a more important purpose that you’ll see in just a second. Now the recipe I’m
using for this makeshift refractory lining, is 1-3/4 buckets full (21 cups) of plaster
of paris, 1-3/4 buckets full (21 cups) of sand. And 1-1/4 buckets, filled (15 cups)
with water. The moment the water touches the dry mix, the clock starts ticking and we’ve
only got about 15 minutes before it all hardens up. So let’s get busy mixing everything
together. It’s really important to get all the dry powder wet, and work out any lumps
as quickly as possible. And after mixing for a couple of minutes, it should be fairly runny,
and roughly all the same color. Now when you’re convinced there aren’t any clumps of powder
left in the bucket, the refractory mix is ready for pouring. So let’s carefully transfer
it to the steel bucket as slowly as practical, to minimize the splattering. There should
be just enough fluid to fill the bucket about 3” from the top, and now if we bring back
our plastic measuring bucket, we can use it to form the center of the foundry. I filled
my bucket with water, to give it a bit of weight, but anything like sand or rocks will
work as well. And you can see that as we push the bucket into the center, the mixture rises
upward, but it doesn’t spill out. Now it’s obvious that the mix is already starting to
firm up, so let’s try working the bucket up and down a few times, to help level it
before it sets. And all we have to do now, is hold still for 2 to 3 minutes. This will
give the plaster just enough time to harden, so the bucket stays in place,even when we
let go. Alright, time for a little cleanup. Everything will still need about an hour to
really harden up, but the plaster’s still soft enough that we can clean and shape it
to look really good. And while we’re here we may as well wipe the bucket down as well.
Now I’ve found that if we dampen a rag and gently drag it around the top, the surface
cleans up really nicely, and gets a cool texture in the process. When it looks the way you
want it too, simply leave it for about an hour. Now while we’re waiting, why don’t
we turn this old steel fire extinguisher, into a custom crucible. You can tell it’s
made from steel because when we hold a magnet to it, it sticks. And magnets won’t do that
to aluminum. I depressurized the tank and unscrewed the valve from the top, to make
it safe and easy to cut in half with a hacksaw. Which you can see just happened in less than
a minute. Now the bottom part of the extinguisher is what we want for the crucible, because
it’s basically a steel cup 3” in diameter, and 5” tall. That’s going to be perfect
for our custom backyard foundry. At this point, the plaster should be pretty well set, so
let’s dump the water from the bucket, then use something like a pair of channel locks,
to grip one edge of the pail, and pull gently toward the center. Now if we grip it with
both hands and give it a bit of a twist, you can see the whole bucket pops loose, and pulls
right out. This just created an amazingly smooth surface, which gives this makeshift
foundry, a surprisingly professional look. The only features we’re missing now, are
an air supply port, and a lid, so let’s make those next. Now I found a 1-3/8” (35mm)
hole saw was the perfect size for accomodating this 1” steel tubing, and if we center the
metal cutting blade with the top line on the bucket, we can carefully begin cutting through
the metal wall. Once we’re through the metal, it’s easy to burrow down at about a 30º
angle because the plaster hasn’t fully cured yet, and cuts away like butter. Now we have a tight,
downward sloping hole, that the blower tube fits perfectly into, and it’s strategically
placed, a few inches up from the bottom. This way, if a crucible fails, and dumps molten
metal into the foundry, it will stay in the foundry, instead of dangerously flowing out
of the pipe. Now the blower tube is really easy to make, and starts with a 1” steel
pipe like this. This is the “business end” that’ll sit next to the hot coals in the
foundry. We’re also going to need a 1″ PVC coupling (Slip x FIPT), as well as some 1”
PVC pipe. You can see the threads on one half of the coupling screw onto the steel pipe, and
the slip adaptor on the other end, simply pushes onto the PVC tube. It’s that easy.
Now let’s go one step further and make a lid to help retain the heat. I got a couple
of 4” U-bolts from the hardware store and stood them upright in a 5 quart, bigmouth
bucket, filled with a half-measure of our insulating mix. (10 cups plaster, 10 cups
sand ,7 cups water). After an hour, you can see the plaster has set, and the whole thing
pops free from the bucket, giving us a nice little custom lid for the foundry. It still
needs a vent hole for relieving pressure buildup, and you could just form one when you’re
casting it, or you could try drilling one with a 3” hole cutting saw like this. With
the hole in the center, you can see we end up with a nice thick lid, that kind of looks
like a giant white donut. This design works great for venting pressure, and gives us the
option to melt metal as well, without even having to take the lid off the furnace. Just
for fun, I picked up a can of “Burnished Amber” spray paint, and gave the foundry
a couple of coatings to make it look a little more attractive. If we get it fired up, you
can see the mini foundry gets so hot on the inside, that it will melt soda cans within
seconds and fill a crucible with liquid aluminum. Look for how to do that, in another project
video. With this homemade furnace, we have the power to liquify aluminum in the backyard,
and cast just about any object we can think of. The best part is, when you’re not melting
scrap metals, rather than taking up space and looking terrible, you can drop in a plant,
and instantly transform it, into fashionable home decor. With this transforming “Flowerpot
Foundry”, there’s certainly “more than meets the eye”. And by the way, if you run
out of soda cans to melt, you could try using it as a blacksmithing forge, or even a bbq,
for summertime grilling. After all, it is fueled by charcoal briquettes. Well now you
know, how to use commonly available materials, to build the mini metal foundry. Powerful
enough to melt metal in seconds, but still pleasant enough keep around for decoration.
Well that’s it for now. If you liked this project, perhaps you’ll like some of my
others. Check them out at

100 thoughts on “How To Make The Mini Metal Foundry

  1. i love this video so much and i am just finding out about his death and now im really sad and heartbroken </3 my deepest condolences to his wife and kids.

  2. does the hole have to be the same size as the crucible or can it be slightly larger? I'm just saying because I made a lid but the hole is well about 4" in diameter. Could I just put a couple bricks over it?

  3. Whaaat. He's gone??? I used to watch all his videos . how did he die. May he RIP my condolences to his whole family and friends. I'm heartbroken 😔

  4. I wounder if there is a way to make it so you can just turn a valve or something to pour the molten aluminum, sort like a oil drain…

  5. possibly the 3rd video i have watched from the TKOR.

    any-who, very interesting, now i can get some plaster and fix the ceiling. . . . and make a unforeseen foundry.

    awesome video !!

    3000 thumbs up !!

    respect = 100

  6. made one twice the size, works well but takes longer to set, if you are making one twice the size like I did, I recommend waiting overnight before use, and on the first firing use only charcoal and no hairdryer, let the charcoal completely burn out and completely cool. it is now tempered and can handle thermal shock.

  7. Can’t find original comment so I’m reuploading: RIP King of Random. This was the first video that I watched. My burgers will always be upside down in your honor.

  8. You guys have truly inspired me to start a hobby. I build my own foundry yesterday using the steel wool to reinforce. I melted down some scrap cans and other aluminium tonight to cast my first muffin ingots. This thing is a blast.

  9. Condolences to his family, however It needs to be pointed out that you should never use plaster of Paris in any way as part of the heat shield like this, calcium in the plaster loses its oxygen molecules and becomes quick lime at temperatures lower than those in a foundry the moment any moisture even the water in your skin comes into contact it will cause a exothermic reaction that at best will cause it to fall apart and at worst give you 3rd degree burns if you can't buy refractory cement use dirt or red bricks.

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