Build a foundry and sand-cast aluminum.

 by Fenris The bbw
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Hello instructableers, DIYers, and Internet people everywhere! Welcome to my debut instructable!!!!
(Whooo, We love you Fenris! You rock! Give me your socks for my creepily obsessive collection of things related to you!).

Thank you, thank you! But really, I must get to the instructable, settle down please.

In this instructable, I will detail how to construct a simple, cheap, and effective foundry, capable of melting aluminum. This foundry can be built quickly, with little tools or money, and is great for beginning metal-casters.

I'm entering this in the Epilog laser cutter challenge, so if you like it (as if you couldn't), please vote.

I'll be your best friend ;)

Step 1: How this is green

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Before I instructify your minds, let me tell you how this project is green.

I live in Hattiesburg, Mississippi, and in Hattiesburg there is no recycling center. The nearest center is in Jackson, Mississippi; which is about 80 miles away. Nobody wants to drive 2 hours just to turn in some cans they could have thrown away in 5 seconds.

That's where me and my friends come in.

Our friends, family, and even random people who just want to recycle bring us pounds of aluminum cans each week, which ordinarily would just be taking up space in a landfill.

We melt down their trash to create tools or art, which we then can either sell or give away.

And though this foundry design pollutes the air with smoke and fumes, it teaches us (and any other beginning metal-caster who wishes to learn with us) what we need to know to build greener, more efficient designs which run off of clean-burning propane or use waste-oil as the fuel (reducing the amount of toxic chemicals people would be dumping elsewhere).

As we learn how to build cleaner, more efficient foundries, I will post instructables, so people in places like Hattiesburg, MS, will be able to do their part to save our planet.

On to the legalities!

Step 2: Legal and precautionary statements.

First off, this instructable deals with fire, molten metal, sharp edges, electrical equipment near water, burning paint/other noxious fumes, and probably some other dangers I don't even know about. If you are a clutzy, hyper, or unattentive person you really shouldn't try doing this.

By reading this instructable you agree that I am not liable for any of the numerous injuries you may incur, property damaged, people harmed, or anything else you could think to sue me over, while building and operating the foundry described within said instructable

That being said, If you follow my instructions you should have no problems with safety. I will do my best to detail the safest way to do this.

Step 4: Materials and tools.

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I built my furnace for nothing, and you can too if you borrow some tools and swipe some trash.

Required to build furnace

Tools
  • Drill with large bit suitable for steel. (Hammer and large steel spike can be substituted)
  • Tin snips

Parts
  • 2 coffee cans of equal dimensions (one for furnace, one for air chamber)
  • 1 hair dryer with a cold air setting
  • 1 tin can (Blue Runner bean cans are the perfect size and are very strurdy)
  • At least 4 metal stakes (optional)

Required to operate furnace

Stuff
  • Instant light charcoal
  • Charcoal lighter fluid
  • Barbeque lighter (the long-nozzled kind)
  • A bucket of water (to cool hot tools)
  • Aluminum cans
  • 3 or more boxes (optional)

Tools
  • Tongs (I use 2 pairs)
  • Some sort of long, metal stick

Safety gear
  • Leather gloves (preferably welding)
  • 100% Leather and/or cotton upper torso/arm coverings (Big Smith jackets are perfect)
  • Gas mask (optional, you can just hold your breath when near the furnace)

Required to make mold
  • a large container
  • sand
  • Something to impint a design in sand with or way to draw in sand (pottery, carvings, body parts
etc.)

Step 5: Building the air chamber

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Use your tin snips to cut a hole in one of the coffee cans for the hairdryer to fit into. It's O.K. if there are some corners that don't quite conform to the hair-dryers nozzle, mine don't and my foundry works just fine (See pic 2)

Step 6: Building the fire chamber

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Using your drill (or hammer/spike combo) make holes in the bottom of the other coffee can. Again uniformity is not a requirement.

Step 7: Assembling the furnace

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There is a simple way to do this-

1. Insert hair-dryer into air chamber
2. Put fire chamber on top of air chamber

-Which is easy as pie but extremely dangerous. If the fire chamber is nudged even the slightest bit the whole thing will topple over, creating a gauntlet of hot coals and molten metal at your feet.

On the other hand though, being able to remove the fire chamber from the furnace gives you the advantage of being able to shake out the coal dust that will eventually clog the holes to the air chamber. This allows you to keep the fire burning hot longer for multiple melts.

If you feel you can't handle having the fire chamber loose, than you should dig a fire pit, fill it with sand, and put metal stakes in the ground running along the sides of the cans. This will hold the cans in place but still allow you to quickly remove the fire chamber.


Step 8: Destroying your aluminum cans.

It is important to seperate the parts of the can, as they all produce different amounts of dross (trash in the metal which has to be removed), and should be melted at different points in each smelting.

The 3 sections which have to be seperated are the top, the sides, and the bottom of the can.

My favorite method for destroying the cans is illustrated in the pictures. Unfortunately, I can't get the image notes to work, so you'll have to read the procedure up here and follow along with the pictures below.

1. Cut or rip the can in half.
2. Make a slit in the top half, perpindicular to the lid.
3. Tear along the slit and pull the siding off of the can top.
4. Make a slit in the bottom half of the can, at an angle to the bottom.
5. Tear as close to the bottom as you can, and remove siding.

This goes much faster if you form a production line with some friends in which one person has one of the steps above assigned to him/her.

I sort the cans into boxes of halves, siding, tops, and bottoms, with the occasional box for cans with painted tops or bottoms.

Once you're done with your cans, it's time to ready your foundry.

Step 9: Laying the coal.

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With the furnace assembled, place a ring of coals around the bottom of the fire chamber (pic 1), Then place two coals perpendicular to the ground in the center of the ring, leaning against each other (pics 2+3). This increases airflow under the can, which helps to heat all the coals and ultimately provides a better melt. The wrong way to do this would be to put one coal flat under the can, (pic 4) blocking airflow from the center of the furnace.

Next put the tin (steel actually) can on top of the two central coals and add coals evenly to the sides of the tin untill it stands on it's own.

Step 10: Making the mold

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If you don't want to make a mold, just some metal blobs (ingots), you can pour the molten aluminum into a muffin tin. The ingots can be re-melted later if you need the metal.

Making a sand mold is easy. All you need is some sand and a way to imprint a design in it.

You could do this with a stick or something, but it probably wouldn't turn out well. I find you get the best results when you use something with a 3-D pattern on it. In this instance I used some pottery, I found at the flea market.

If you have a friend (or friends) working with you, they could make a cool design, while you melt the metal.

Now all that's left to do is prepare your work-space.

Step 11: Foundry Feng-shui.

There are a million possible misfortunes waiting in a foundry, and you can eliminate almost all of them by being prepared.

I have here some pictures of my foundry set-up and running, as well as some pictures of me operating it.

Notice that the cords are held away from the walkspace with a bucket so I won't trip on them, and that the water and aluminum (i.e. conductive materials) are on the other side of the walkspace.

You need to be able to walk in a complete circle around the furnace without bumping into anything.

The water and mold need to be where you can reach them quickly when you need them, but not so close to you that you bump them.

If you've done all of the above, it's finally time to start up you're furnace!

Step 12: Starting the furnace. (FINALLY!)

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Make sure all your safety gear is in place and then get ready to finally do some metal-melting!

First load your crucible half-way full of can tops, they burn the cleanest, so burning them first yields more molten aluminum to submerge other can parts in.

Then, light the charcoal!!! Whoooo! fire!

If you use regular charcoal, you have to use lighter fluid, which can drip through the furnace onto the hairdryer, for this reason I only use coals that light instantly in my furnace.

As soon as you think all the coals under and around the crucible are lit, start the hair-dryer.

Next you need to add coals to the side of the crucible untill they form as even a layer as possible around it's center.

Once the can tops start to melt and you can see the can glowing red it's time to move on to the next step.

Step 13: Operating the furnace.

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I had several instructional videos to show you, but my mother managed to unintentionally delete them off of her camera.

The world weeps.

It's O.K. though, operating the furnace is pretty straight-forward.
All you really need to do is

1.Fill the crucible of aluminum scraps
2.Cool the tongs in water
3.Let the aluminum melt
4.Use a metal pole to remove dross (Gross stuff floating at the surface)
5.Cool metal pole in water.
6.And repeat

If you don't have a gas-mask then you need to hold your breath when you feel hot air from the furnace hitting your face

Aluminum scraps should be melted in this order; can tops, can bottoms, and then can sides.
This is in order of metal-to-dross yield.

Dross should be removed quickly after the aluminum melts, or else it will clump together with some of the aluminum and stick to the sides of the can, reducing the amount of pure aluminum you can get per pour. There are some pictures of me removing dross below.

Also you must be careful with hot tools, not only because they can burn you, but because they can burn other things.

For example, If you use hot tongs to try to grab coal out of the coal-bag, the coal could ignite setting the entire bag aflame.

When you notice that the crucible's glow is starting to fade, either add more coal to the fire, or prepare your mold for pouring.

Step 14: Pouring the mold

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The most self-explanatory step. Pick up your crucible with your tongs and pour the molten aluminum into your mold.

The aluminum has a smooth look to it's surface while it's still molten, but if you watch closely, you can see it start to crystallize.

Try not to pour from too high or the aluminum will crush the detail out of the mold.

Again, I apologize for the lack of videos, I'll try to upload some soon.

Here's a pic of the finished product. (I didn't use enough aluminum) :(

Step 15: Come on...

...lets be honest with ourselves, you know you loved this instructable, I know you loved this instructable, we both know you loved this instructable. So why are we playing this game? Stop playing coy and vote for this instructable!

Seriously though, the laser cutter would be put to good use.
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jadronx says: May 21, 2013. 8:08 AM
Wonderful instructable! Aside from the lack of face shield that is. I am excited to see what new designs you come up with.
man ray says: Jun 10, 2009. 1:46 PM
what did you use for a crucible?
skatattookid in reply to man rayApr 24, 2013. 7:17 AM
my crucible was an old fire extinguisher that i cut the top off with a sawsall. works great!
Fenris The bbw (author) in reply to man rayJun 22, 2009. 12:14 PM
A tin can.
Wyle_E in reply to Fenris The bbwAug 4, 2009. 9:43 PM
That was certainly a steel can. BTW, I've seen a lot of aluminum soup cans lately. They usually have pull-tab tops. Before you use a food can for a crucible, check it with a magnet. The best cheap crucible for aluminum and zinc alloys is a short piece of steel pipe with a piece of steel plate welded over one end. I haven't checked with local welding shops, but it would probably cost less than the cheapest clay-graphite crucible from Budget Casting Supply. There are a *lot* of web sites devoted to amateur foundry. www.backyardmetalcasting.con is a good start.
bshelton4 in reply to Wyle_ESep 11, 2011. 6:29 PM
I can make you some stainless crucibles if you would like or carbon steel. I take paypal so you are covered and ship USPS.just need to know the size and what kind of material you would like. 256-309-9406 is my number. Thanks.
Fenris The bbw (author) in reply to Wyle_EAug 6, 2009. 2:05 PM
I think i adress that most cans are made out of steel somewhere, but for the life of me, i can't figure out where. Probably in the comments somewhere. Also, a welded crucible would probably work better, but I'm trying to make this build as simple as possible so others with no experience can replicate it.
legendeveryone in reply to Fenris The bbwDec 10, 2009. 1:47 PM
Can you use a glass bottle or container as a crucible? I know it has a much higher melting point than aluminum and is somewhat easier to come by than steel.
Fenris The bbw (author) in reply to legendeveryoneDec 11, 2009. 7:18 PM
The short answer, no.

The long answer no becuz it'll explode, or at least crack, which would waste all the aluminum.
backyardmunitionist in reply to Fenris The bbwOct 1, 2009. 2:50 AM
Have you ever tried a ceramic crucible? I was wondering if you would get a purer product if you didn't have the ferric metal possibly alloying minutely with the aluminum.
Fenris The bbw (author) in reply to backyardmunitionistDec 11, 2009. 7:17 PM
A ceramic crucible would be awesome. But I'm trying to keep it cheap and only use garbage for my materials.

Also, I don't think the steel alloys with the aluminum at all, but rust flakes might get in the melt if you use the same crucible more than once.
leifbus in reply to Fenris The bbwMay 18, 2010. 11:54 AM
 Could you make a crucible out of plaster? (since you could cast the aluminum into it anyway?)
Wyle_E in reply to leifbusMay 26, 2010. 8:12 AM
Plaster, like portland cement, sets by a hydration reaction.  Get it hot enough and it dehydrates, turning back into dust.  The furnace is going to be a lot hotter than a mold full of molten metal.
rsmigielski says: Jan 5, 2013. 2:56 PM
what kind of gas mask filter will cleanse the toxic fumes form the cans?
brsild says: Oct 21, 2012. 9:01 AM
is there a way to set it up to melt stainless steel?
jbend says: Jul 2, 2011. 8:44 AM
can you use wood insted of charcoal.
farmboy15 in reply to jbendSep 18, 2012. 2:17 PM
Yes you can i have used wood alot just cut it into kindling then it will turn into hot coals quickly which are easily able to produce the heat required for melting aluminium
letstormdufield in reply to jbendAug 21, 2012. 3:34 PM
No, Wood will not burn hot enough
skatattookid in reply to letstormdufieldApr 24, 2013. 7:12 AM
wood does burn hot enough. i do it all the time.. in fact thats all i use to smelt my aluminum. granted you use alot of wood but if your like me and you have alot of trees on your property then its no problem.
trigger ects says: Aug 2, 2012. 6:08 AM
what sand did you use and how much water do i put in the sand
trigger ects says: Aug 1, 2012. 2:01 PM
im going to make this just got to find the coffee tins
Wiredfey says: Jan 7, 2012. 10:30 AM
Question,i have a heat gun which i use to take off formica when doing remodel and use it to melt ice. would this be more effective?
Fenris The bbw (author) in reply to WiredfeyFeb 9, 2012. 12:39 AM
No.

Hot air is less dense than cold air, and consequently contains less oxygen.
I know it's counter-intuitive, but colder air burns better.
Wiredfey in reply to Fenris The bbwFeb 9, 2012. 8:23 AM
that's kind of funny but interesting :) thanx,time to hit up a goodwill for a dryer.
Deadskull57 says: Aug 25, 2011. 4:31 AM
Cool, I've been looking for a good foundry instructable, looks like I'll be taking a trip to the goodwill for a cheap hairdryers.
TimmyMiller says: Jun 18, 2011. 9:45 AM
what if you just removed the paint from the cans?
canis says: Jun 3, 2009. 2:38 PM
cannot stess the importance of a face mask here. no matter how well prepared you are, unexpected s#!+ happens. a cheap lexan face mask from a local welding supply is a lot cheaper than skin grafts - and a hell of a lot less painful.
canis in reply to canisJun 3, 2009. 2:39 PM
P.S. i got my degree i bronze casting specifically, and i have a ton of experience with all manner of aluminum casting. i know whereof i speak.
Fenris The bbw (author) in reply to canisJun 4, 2009. 9:28 AM
Thanks for the advice. You can get a degree in casting? That's awesome, I'll have to look into that.
canis in reply to Fenris The bbwApr 28, 2011. 3:49 PM
Not bronze casting specifically, no LOL. But bronze was my emphasis in my sculpture degree, which is as close as one gets, I suspect.
junits15 says: Sep 24, 2009. 6:12 PM
put a rol of pennys in, they if its hot enought, they will burn blue.
trknust in reply to junits15Apr 24, 2011. 8:40 AM
DO Not do this with pennys. This can hurt you fast. Most pennys now are made out of Zinc and will poison you if you breathe the fumes when it is melted or burning.
They have a very thin coating of copper over the zinc cast.
If you want to melt copper, use old copper tubing or wire with the plastic removed. Just make sure it is realy copper all the way through.

And to prevent oxidation a little bit of hundred mule team borax floating on top works like a champ.
Kurt_ says: Dec 16, 2010. 8:36 PM
Sand Casting actually involves clay to stabilize the sand so it doesn't crumble, and so you can have a two-piece mold like in industrial uses.

Other than that, nice instructable. It's ghetto-tastic, just the way I like it!

Read how to make casting sand here:
http://www.ehow.com/how_6065035_mix-sand-casting-aluminum.html
sniperHunted says: Oct 27, 2010. 4:03 PM
can you hook up a miniature A/C in replacement for the hair dryer.
sniperHunted says: Oct 18, 2010. 10:20 PM
will it work with brass?
general-Insano in reply to sniperHuntedOct 27, 2010. 8:58 AM
yes it could work with brass but you will have to be very careful in not letting the copper and zinc separate.
Firestorm_101 says: Sep 29, 2010. 7:32 AM
How do you make 3d designs like ring, bracelets, bangles, etc? Could you put a material within the sand with a gap uptop, that would incinerate immediately while pouring in the molten liquid?
badideasrus in reply to Firestorm_101Oct 6, 2010. 9:17 PM
..... it wont let me reply to myself..... oh well. the show was called 'animal face-off' i can't find a full video, so i cant find the casting stuff, but i liked it so much i wrote it down as a kid once..... so i'm pretty sure i've got it right. the only thing (besides it being a special sand or not) was weather they used a sprue hole..... which kind of ties in to the sand being special or not, cuz iron sand would melt, making a hole...

but hes, you could use a burnable material.... look up lost wax casting. same thing, basically, just without the sand.

==========================================================note:
sand casting wouldn't work so well with jewelry, though..... unless you have extremely fine sand, your detail level will be degraded, cuz your detail is restricted to the size of the grains of sand. if it's course, it will leave pits and bumps in the surface of your jewelry.
badideasrus in reply to Firestorm_101Oct 6, 2010. 8:58 PM
there was a show were they would see which of two animals would win if they ever got into a fight. i loved the show, not only because of the awesome idea, but because they always made a black iron replica of said animals skull (complete with teeth) or claws or what not .... ON THE SHOW. they even exsplained what they were doing.

they would pretty much do sand casting, however they would use foam, like styrefoam, that they carved into shape, and just pour the molten metal onto the sand. i don't think they even made sprue. of course, i think they used iron sand..... may be important....

the downside to this is that the metal was kind of pitted.
neorazz in reply to badideasrusNov 14, 2010. 6:08 AM
i remember that show they would overcast the teeth and then polish them down to size i though them to be unrealistic in comparison to the same size tooth in enamel/bone (much higher psi before breaking) but the metal work idea is sound if your making your own foam molds enlarge them a bit then you can machine off the excess for a good finish where you need it
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