Casting an Aluminum Anthill

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Posted in WorkshopMolds-and-casting

Introduction: Casting an Aluminum Anthill

Casting molten aluminum into anthills is definitely not an original idea, but I still wanted to try it. When you normally cast aluminum into sand with a foam mold, the most exciting moment is when you first pull it out and see if it worked or not. When doing this with anthills, it is even more exciting. If you use a foam mold, you know generally what the finished piece will look like, but with ants, you have absolutely no idea of what will come out of the ground. When I came across a large opening for an anthill in our driveway, I had to give it a go.

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Step 1: Video

Step 2: Preparing the Anthill

Before you can even begin, you have to locate a large anthill. I have tried to cast the little tiny hills that pop up on sidewalks and roads, but have never had success in casting them. My guess is that the tiny hole fills up with sand before the aluminum can enter, or the surface tension of the metal is too high to allow it to flow. Don't get discouraged if you can find one right away. I just kept my eye out for a while, and eventually found one that was perfect.

After you have located the colony, it is a good idea to build up the sides a little bit. When you fill up the anthill, you need to have head pressure or the metal won't flow down as far as it should go. To achieve this pressure, a reservoir of aluminum needs to sit above and keep force on the molten metal. If the sides aren't built up to make a dam, it just spills out and you get a 1,221°F mess to clean up. To avoid this, I used sand taken from the Mississippi river and formed a bowl shape with the entrance hole in the center. Make sure to not spill any sand down into the hole.

That dam serves another purpose once the aluminum is cooled off. You can flip the entire structure over and you have a solid base to hold it on.

Step 3: Forge Preparation

When your anthill is prepped, you can start on the forge. My "forge" isn't really a forge at all. It consists of a couple fire bricks arranged in a semi-circle with a furnace blower aimed at the opening. I have used normal bricks in the past, and they do work but all end up cracking from the heat.

The forge runs on scrap wood. It would be much better if I used charcoal or coal, but scrap wood is free, and works well enough with enough air supply.

For the aluminum supply, I find reusing old soda cans works very good. You can use scrap aluminum, but it is more difficult to melt, and the pop cans melt within seconds. You will need a decent amount, and they can be easily found at recycling centers or even picked up on the side of the road.

Importantly, don't forget the necessary safety equipment (fire extinguisher, welding gloves and apron, face shield, tongs, etc.)

Make sure to have everything you need to completely finish the process, because once you light the forge, things move along really fast, and you often don't have time to run inside and grab more supplies

Step 4: Melting and Casting

After you light the forge, you can start to blow more air into the fire. The rate of which the air is supplied really determines how hot the fire is. You have to be careful though, you cannot move the fan too close or you could risk blowing coals out of the forge.

After the first couple of cans are melted, things move along faster. The aluminum that is already molten surrounds the new cans and heats them up much quicker. Keep melting more until you are sure you have twice as much as you need. When I pour the aluminum, I find that I always could have a little more, so it is better to be on the safe side. You don't really know how big the anthill is, so it is better to have too much instead of too little.

Be gentle when pouring. It is easy to knock a rock or a bunch of sand into the hole, clogging it up.

Step 5: Digging It Up

After you let the casting cool for a long while, the fun part can begin. I actually let mine sit for only an hour or so, and while digging it up, still felt the intense heat. The dirt surrounding the casting insulates the aluminum, causing it to stay hotter for a longer period of time. Be cautious when pulling it out of the ground, you can break off little chunks (I accidentally did).

After the casting is out, pour water on it to cool it down and clean out the dirt and rocks.

Step 6: Base Construction

After the piece is removed from the ground, you could stop right there. I wanted a nicer base to sit on, so I decided to build a custom one. The casting came out with a longer oval shape, so I drew a suitable shape onto a piece of 1/2 inch red oak. You can easily draw ovals similar to mine by securing two nails a distance from each other, and using a loose loop of string strung in between them. Once the shape was drawn, I used my cheap not-very-good bandsaw to it out.

I knocked off the edges with a chamfering bit in the router. Also, I drilled a small hole and pounded in a little aluminum rod to help support the weight of the casting.

Step 7: Finishing and Gluing

I finished the base with two coats of water-based varnish. After the first coat dries, I sanded it with fine steel wool and brushed on the second coat.

I attached the casting to the base with glue. The bottom of the base wasn't flat, so I needed a glue that would foam to fill the gaps. I really hate using it, but I resorted to Gorilla glue. When it foams, it fill gaps nicely, but also swells and covers everything that you didn't want covered. To prevent this, I applied only a small amount to the center of the base. For the support rod, I used 5 minute epoxy, which is definitely a more reliable friend.

Step 8: Finished! and Etsy

After the glue was set, the project was completed. It was definitely a fun one, and I might revisit it again in the future. If you are interested in buying this piece I have made it available on Etsy here.

Again if you liked this Instructable, don't forget to vote, comment, and favorite. It really helps me out!

Thank you.

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    44 Comments

    Awesome!!!! I have got to try this!!!

    How do you polish the aluminum when once you have your sculptchur? Seems like it would have bits and pieces in it depending on whats in the ground.

    What's your crucible

    It looks like an upside down enterprise. Lol. I want to melt a bunch of pennies and pour it in an ant hill.

    It looks like an upside down enterprise. Lol. I want to melt a bunch of pennies and pour it in an ant hill.

    Awesome instructable. I look forward to doing this this summer.

    How did you determine it was an abandond or otherwise unoccupied nest site?

    1 reply

    Well, It's a good thing they were ant's that were actually in an inconvenient place,..
    I would hope people don't go out of their way to find and do this to ant hills in more out of the way spots where the ant's don't really bother any people.

    2 replies

    Oh, I indeed would. Pesky bugs are pesky bugs whether ants, spiders, flys, etc. Remember when we were kids and we would pull off the wings of flys and use a magnifying glass to burn spiders. Those were the days.
    I absolutely want to try this and I'm going to hunt this summer for any ant hill I can find to do this cool instructable. I'll do it more than once just for good measure.

    I agree completely. Insects are essential to life on Earth. Our very existence depends on them. They should be left alone unless they are causing a problem.

    There are literal genocides being committed today (today, as in today, this day, right now, as you're reading this) in the middle east and being broadcasted on youtube...

    But this ant hill... this is really where the focus should be.

    The ants/spiders/(insert any bug here) are there for our amusement. It's hilarious fun creating ant/bug genocide.

    Oh no! A reality check! :^)

    Great instructable. I told my father in law I had a guaranteed way of getting rid of the fire ants in his yard. When he saw this, he laughed.

    These are ants folks. They are certainly NOT in danger of becoming extinct. They rapidly breed and become a major nuisance in many, many homes. If we want to get politically (IN) correct over this - let's put our efforst into gettign behind the families who list their sons when our government official murderd our men in Benghazi...rather than a colony of ants.

    Unfortunatley the ground is so full of rocks where I live that I cannot do this. So anyone concerned can take solace in the fact my ants will be OK... and I continue to have to spend money for a spray around the base of my house so they won't keep coming inside. :^)

    4 replies

    I wouldn't say it's guaranteed. Those fire ants are crafty little critters. They have the most uncanny ability to survive just about anything.

    Ants are an extremely important part of our ecosystem and they should not just be slaughtered wholesale, regardless of how prolific they are. The people who are concerned about exterminating them are correct. Extermination of any insect should never be done unless it is necessary.

    Fire ants are of course an entirely different matter, as they are an invasive species that is actually doing harm in the areas of the USA they have invaded.

    But this instructable is not about slaughtering them wholesale. Maybe if the government wasted more of our money to illogically develop a kill-all ant chemical and spread it around, then there might (?) be s light possibility it would be a wholesale slaughter and exterminate all ants But tell that to the mindset behind DDT - the flies are still with us in abundance - and not just because it became illegal to use. Some flies were already resistant and so now we have those that bred and have DDT resistant flies.

    There is no way someone making a life-ling hobby out of this ant casting is even going to make an infinitesimal impact on the ecosystem b/c the system is so huge and there are so very many ants. The typical mindset pushed by our media nowadays is to keep people worrying and frustrated over the minutiae so they miss the real problems - and again I refer to the Benghazi murders and the slaughter and slavery of fellow humans worldwide. Where are these same people worrying about something impossible concerning ants when real issues arise? I would hope making just the same amount of noise.

    The worst part is most of the advice about the "facts" of nature come from people who are foreign to nature. If they dare venture out, they have to take their conveniences with them just to survive (tent, stove, backpack, sleeping bag, etc. etc.). Its like an African bushman trying to dictate what stocks to invest in. He could only after years of training and education by exposure.

    Relax friends - the ants will be here long after you and I are gone. But our personal freedoms likely won't be passed on to our grandchildren b/c we were having our passions redirected to issues which deserve just a common sense approach while the real issues, and those behind them, got away with murder.


    Jacques Cartier was the first European explorer to report on passenger
    pigeons, finding them in abundance on Prince Edward Island during his
    first voyage in 1534. His famous quote: “Relax friends- the pigeons will be here long after you and I are gone.“.

    The species went from being one of the most abundant birds in the world
    during the 19th century to extinction early in the 20th century.
    Martha, thought to be the world's last passenger pigeon, died on
    September 1, 1914, at the Cincinnati Zoo.

    https://en.wikipedia.org/wiki/Category:Species_made_extinct_by_human_activities

    OK...

    If you want to start hunting down ants and eating them then go ahead. The fact the Passenger Pigeon was large, slow, largely unafraid of man, and people liked to eat them was why they were hunted to extinction (although there has been some talk of genetically reviving the species.

    Another factor to consider is that the world population of ants is a lot more than what the state-covering passenger Pigeons ever were... and there are a lot less people wanting a free meal by killing ants.

    It is all about true perspective in nature and not some media causing hype over something very much NOT understood by those making the claims.

    We need conservation - agreed - but the day we start trusting people who cannot even tell you which gender a deer is by looking at the tracks alone, or that has never built a fire in the woods with no gasoline (modern tools or other chemicals) to say what the FACTS are about a world they have insulated themselves from is the day our man-made, synthetic bubble of reality has gone to ridiculous levels.

    Comparing the plight of the Passenger Pigeons to ants is rather an (trying my best to NOT sound critical - neither of us want that) ... interesting.