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  • Things aren’t always what they might appear to be. For example, this decorative houseplant

  • youre looking at, is actually an artfully disguised, metal melting furnace. In this

  • project were 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. Were 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 itll also serves a more important purpose that youll

  • 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 weve 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 youre

  • 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 were 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 were 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 were 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 were 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 thebusiness end

  • that'll sit next to the hot coals in the foundry. Were 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 youre 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 ofBurnished

  • Amberspray 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 youre 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 transformingFlowerpot Foundry”, there’s certainlymore 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 youll like some of my others. Check them out at www.thekingofrandom.com.

Things aren’t always what they might appear to be. For example, this decorative houseplant

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B2 US bucket plaster metal steel sand melt

How To Make The Mini Metal Foundry

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    何紹愷 posted on 2015/02/08
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