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DIY Foundry



How To Cast


Blue Salamander

Bronze Casting

Now let's all be honest: if you don't enjoy making a fire hot enough to melt metal, there's probably something wrong with you. So, you should either seek some professional help or continue reading.

Great! Now the "who" and "why" is out of the way. "Where"? Someplace safe, like outdoors on a concrete slab. Don't be stupid and burn down your grandmother's apple tree or your spare bedroom. It's fire, dummy. It's hot and might burn nearby stuff. Consider this a legal disclaimer: I am not an expert. Any advice you take away from this page may well get you hurt, killed or divorced. Don't come crying to me when you've burnt your house down, it's your own damn fault for following my amateur advice. Now let's get on to the "how"!

Building your own!

Sure, you could go and get an electric or gas-fired foundry to melt your metal. But hey, those things are expensive! And there's a certain pride you get from making your own tools, I find. So we'll be building a charcoal-fueled foundry capable of melting alumminum, copper and bronze. Maybe steel too, but I haven't tried it and it's probably too inefficient for that. I don't own a copy of it, but I'm told that there's a Gingery book on just this topic. It's probably well worth buying.

Not counting fuel, tools or metal, here's a short list of some of the things you'll need for this project:

  • A metal bucket with lid. Make sure it's big enough!
  • Refractory cement. This stuff is pricey, and will probably be the biggest expense. How much you need will depend on the size of your bucket.
  • Portland cement and sand (optional). If you're doing things on the cheap, like I did, you can do a two-layer design with the outer lining of your foundry using a mix of portland cement and sand. This cuts down on the ammount of expensive refractory cement you'll need
  • An assortment of iron pipe fittings. You need to provide a way to force air into the bottom of your foundry. I wanted a little cleanout at the bottom of my foundry, so I used a t-junction, an end cap and a couple lengths of pipe. If you don't want the cleanout, you can get by with just an elbow.
  • A cheap/used/free hairdryer with a round nozzle end. Preferrably, one whose heating element is mostly crapped out.
  • Whatever PVC pipe fittings you need to adapt the nozzle end of your hair dryer onto a piece of iron pipe just big enough to fit onto the stub coming out of your foundry.
  • Scrap styrofoam. You'll use this to form the shape of the cavity in the center of your foundry.
  • Some coarse-thread drywall screws (1 1/2" long) and steel wire. This reinforces the refractory and/or cement, and helps keep it in place in case it cracks.

Now that we have our supplies, let's get started. Start off by assembling your iron pipe bits and cutting holes in the bucket in the suitable locations. Put the pipe into position and try to keep it from moving about. Mix up a 50:50 ratio of sand and portland cement and get it just wet enough so that it holds its shape when you squeeze it in your fist. Pack this stuff around your pipe, about 1" deep. Let it cure.

OK, next take that styrofoam and cut it into circles 1" wider (in radius) than the interior cavity of your foundry will be. Carefully carve up the bottommost panel so it will fit snugly around the exposed pipe bits at the bottom. Use some duct tape to hold it together into a big cylinder. Put the styrofoam cylinder into the foundry; the pipes at the bottom should keep it centered. If there isn't at least 1" of space between your styrofoam and the edge of your bucket (remember, your bucket tapers towards the bottom!), your cavity is too big and you aught to make it smaller. Hopefully, that won't be a problem. Now take some of the screws and put them through the side of the bucket into the styrofoam. It will probably help to pre-drill the holes in the side of the bucket.

Mix up some more of that sand/cement mixture and pack the cavity betwen the bucket and the foam. Use a stick to make sure it's in there good and dense, without any airspaces. Leave the top of the cement mixture about 1" below the rim of the bucket. When it's good and cured, here comes a tough part: Using a long knife, cut through the styrofoam 1" from the edge. Take out that center disk and save it (it'll be the formwork for a following step), and just tear out the 1" wide 'donut'. Careful, there are screws in there!

Now we work on the lid: Start by removing the handle. Then cut a 2"-3" round opening in the center. I took some scrap steel I had laying around and made up some handles and screwed them to the top of the lid. Drill some holes around the edge and run the wire from hole to hole in a star-shaped pattern, being careful to avoid crossing the hole in the center. Cut a styrofoam plug the same size as the hole. Cover the hole with duct tape and stick the plug to the tape.

Plug up the hole in the pipe in the bottom of your furnace with a bit of tape. Cut a couple long, triangular peices of styrofoam, long enough to reach from the pipe almost to the edge of the cavity. Mix up some of that refractory cement according to the label on the side. It doesn't go very far, so make sure to mix up a bit more than you think you'll need. Now fill up the bottom of your foundry with the refractory, enough to reach the top of your pipe. Press those triangular bits down into the cement (these will form drains/vents). Pour any extra refractory into the lid.

Just like before, tape together those styrofoam disks and, once the refractory in the bottom is cured, put the plug into the cavity. There should be a 1" gap all the way around. The screws shouldn't be sticking into the styrofoam now (if they are, cut them off), so keeping it in place will be a little tricker. Mix up more refractory and pour it into the cavity. Again, use a stick and jostle it around while it's wet to make sure there aren't any air pockets. Fill up the bucket all the way to the top and out to the edge. Finish filling up the lid. Once the refractory cement is cured, pry out all the styrofoam and remove the tape. Congratulations! You foundry is now done, minus the blower.

Now for the blower. For our purposes, a cheapo hair dryer will work just fine. I wouldn't spend more than $8 or $10. If you can get a used one cheap or free, even better. It aught to have at least two speeds and a round nozzle end. I tried removing the heating element from mine, but it turns out the heating element is also the resistor that controls the speed, so you probably should just leave it alone. Find a PVC-to-threaded-pipe fitting that will fit onto the end of the dryer and glue it in place. You want to get a decently long (24" or so) iron pipe wide enough to fit over the end of the pipe sticking out of your foundry. You need to be able to easily remove the blower from the foundry (you'll find out why later), and the pipe needs to be long enough that it won't conduct heat into your plastic dryer and turn it into a melty mess.

Building your own foundry tools...Not recommended

Many people are certainly capable of making their own foundry tools. Heck, I did it. Twice. Because the first set was a hunk of junk and dangerous. Why is why I don't recommend it. If your foundry, big deal. As long as you're careful and have a fire extinguisher handy, you'll probably be OK. If your crucible shank fails at a critical moment, however, all of a sudden you've got molten metal splashing on your feet. Not cool.

To do some casting with your new foundry, you'll need a crucible, crucible tongs and a crucible shank. Having some long-handled pliers and a skimmer would be a great idea, too. You'll probably think of other tools you'll need as you go along (like ingot molds. I use a cast iron egg-poaching pan I got at Goodwill). Budget Casting Supply has a great selection of reasonably priced tools and foundry accessories (as well as metal stock).

That being said, I did make my own tools, and I think they turned out pretty well. But I'm a decent welder, and I've got no one but myself to blame if they fail. I've had several people recommend making your own crucible out of steel. I certainly could have, but I didn't, and here's why: while I'm only casting bronze (at best), some of my original tools failed because the foundry was actually burning away the steel. Fortunately, it was just poorly made tools and not an actual crucible full of molten metal. Plus, there's quite a bit of metallurgical proof that molten aluminum, copper, tin, etc. slowly eats away at steel (which then ends up in your casting metal). You know, for $40, it's just worth getting a clay-graphite crucible.

Casting Media

While melting metal sure is fun, it's only half the journey. Once it's molten, it's time to do something with it. You've basically got 3 choices: Sandcasting, lost wax casting and (for certain lower-temperature metals) silicone casting. As I've got the most experience with it, I've chosen to focus on sandcasting for the moment. There's a Gingery DVD on that, too. I don't have this, either, but it sure looks neat.

I've decided to give K-bond a try. By many reports, it's about the best sandcasting media out there. Some of the materials (like Bentone) can be very difficult to obtain in small quantities. I haven't actually been able to put it to work yet, but I'm eager to!

How to cast metal, in brief

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Some of my casting projects

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Copyright Joel & Angela Cropley 2009
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