Introduction: Coffee Can Aluminum Foundry

Picture of Coffee Can Aluminum Foundry

Here I'll show you how to make a furnace for melting aluminum. The materials can be bought from Wal-Mart and your local hardware store. Cost to build furnace alone: $23 Cost of furnace and materials + tools to operate it: $50

*** 5/31/09 *** I will be making a new, revised charcoal foundry instructable as soon as I get some spare money. This setup is adequate, but there's always room for improvement.

Step 1: Materials and Tools

Picture of Materials and Tools

Required to build furnace...
-One normal sized coffee can (6")
-One hair dryer with a cool mode and preferably two speeds
-Duct Tape
-One 1.5" x 10" galvanized/black iron pipe nipple
-One soup can
-Tin snips

Required to operate furnace...
-Long tongs or pliers to grip crucible
-Steel spoon w/ holes in it
-Heavy leather work gloves
-Lighter Fluid

Step 2: Making the Furnace Shell

Picture of Making the Furnace Shell

Using the tin snips, cut out a square/circle (square is easier!) in your coffee can. Make sure it's big enough to accept your size pipe nipple. (In my case 1.5")

Step 3: Making the Forced Air Blower Assembly

Picture of Making the Forced Air Blower Assembly

To make your blower, take the duct tape and connect the hair dryer to one end of the iron pipe nipple. Turn it on and check for leaks.

Next, use a little piece of tape to make sure the cool button will be held down constantly.

Step 4: The Crucible

Picture of The Crucible

Our crucible here is simply a tin/steel soup can. They're cheap/free, they melt at a higher temperature than aluminum, but they're one time use. Don't attempt to use it twice or it will melt through spilling your precious aluminum on your furnace.

Step 5: Using the Furnace

Picture of Using the Furnace

I could make another instructable on using the furnace and melting aluminum but I'll be nice enough to include it in this one. :)

Starting it...
1. In the area between the outer shell (coffee can) and the crucible (soup can) put in your charcoal.
2. Drench it in a generous amount of lighter fluid.
3. Light it.
4. Wait for the lighter fluid to completely burn out before you turn on your blower.
5. The furnace is now ready to use.

Melting Aluminum...

A little info on metalcasting:
Aluminum cans tend to oxidize and burn rather than melt because they are so thin. If possible, find another source of aluminum such as lawn chair tubing, roof flashing, etc. If, like me, you use soda cans, crush them flat first to reduce surface area and they'll melt fine but with a lot of slag.

Soda cans per pound of aluminum they'll give you:
12 cans = 1/3 lb.
24 cans = 2/3 lb.
36 cans = 1 lb.
-Those are not exact numbers, but rather close. It's the best website I've seen for metal casting, building furnaces, etc.

1. When the furnace is ready and the crucible is glowing red hot, put in your aluminum.
2. Wait for it to fully melt and get very hot so it will all pour it and not remain in your crucible.
3. I pour my aluminum into mini-muffin tins to make ingots, which can be later re-melted.

-The furnace gets VERY, VERY hot during operation. ALWAYS use the leather work gloves.
-Before melting aluminum, let the can heat red hot to make sure it has an oxide coating. If your soup can does not, the aluminum could eat through the can. Getting an oxide coating is as simple as getting the whole thing to red heat. It will take on a dull blue gray color when ready.
-Make sure there is NO water in your source of aluminum. This could result in molten aluminum explosions.
-Use common sense.
-Liquid aluminum is hot enough to burn through many things.
-Keep your hair dryer away from the furnace during operation. I do not fully insert the iron pipe nipple into the furnace because it blows too much air (yes, on the low setting) and it gets too hot. Just aim your blower at the hole you made and it will get very hot. Trust me.
-However, if you choose, you can fully insert your blower into the furnace if you desire that much heat or your crucible requires it. It won't kill your hair dryer as long as you have a 10-inch or more length of iron pipe nipple between the furnace and hair dryer.
-I used a galvanized iron pipe nipple because that's all Home Depot had in stock. I HIGHLY advise against it. When galvanized things reach a certain temperature, they give off extremely toxic fumes which can give you Metal Fume Fever. Use black iron if possible. If you use galvanized, you have 2 options. Don't stick the pipe directly in the furnace, or heat the whole thing up and burn off the coating. If you choose the latter, stay away from it while it's burning off.

I was thinking this could be used as a mini-forge too. Just don't use a crucible, keep the forced air, and you could heat metal with it. While I don't think it will get it hot enough to actually forge something, I know for a fact it can be used to anneal and harden steel. I make small knives out of shaped and sharpened files with the teeth ground off, and it would work for those. I'll post here in this paragraph if I ever do that.

-Thanks for looking! Watch for more Instructables over time.


davidcondrey (author)2016-09-27

If you really need more heat, make some thermite and replace your charcoal with thermite bricks. Pretty easy to make: aluminum powder + red oxide powder mixed and formed with a binder like plaster.

ScottB12 (author)2015-01-11

I see a flaw in this... If you use a "tin/steel" soup can... Aluminum melts at 1220 F, Tin on the other hand melts at 450 F (at least according to the details I've found, I haven't personally tested it, because I don't have any definitely tin cans.)

So unless you mean Tin-Steel alloy of some sort when you say "tin/steel soup can" a tin can would melt before you were up to temperature to melt aluminum.

I can't promise you won't have accidents, but if using a soup can, please make sure it is steel, not tin.

trask (author)ScottB122015-01-14

"Tin" cans are just what they're called. Due to the price of tin, these days "tin" cans are made from steel, sometimes with a tin coating inside for corrosion resistance, although now plastic coatings are often used,. If soup cans were made tin they would cost nearly $1.00. Tin is around 10x the price of aluminum and many times more costly than steel alloys.

ScottB12 (author)trask2015-01-14

The reason I bring this up is simple. Many people will build this as a hobbyist. The temperatures involved and the risks of mishaps are significant.

My comment was largely intended to alert the people trying to recreate this, that there are some serious dangers of they use a "tin/steel" can that turns out to be a tin can, the can will melt, while even using a steel can, the temperature might become hot enough to even make cheap steel risky. Some steel can become soft about 1000 F, while aluminum properly melts at over 1200 F. Some steel could breach before the aluminum melts.

Antbal0 (author)ScottB122016-04-28

tin cans, like tin foil, aren't usually tin.

david foeckler (author)2016-02-16

How long does it take to melt the aluminum?

SeanJ12 (author)2015-10-21

Could I use woodchips instead of charcoal? Also, doritos burn hotter than charcoal.

fragmaster4 (author)2010-06-02

Just a safety precaution, Aluminum gives off harmful vapors when melted; Wear some kinda mask at the least.

AJMansfield (author)fragmaster42012-05-31

Not really. Anyway they're much less harmful than the other vapors the whole process will be producing, so you really should only worry about that if you have fixed all the other odor problems first.

antioch (author)AJMansfield2012-06-08

Unfortunately, fragmaster4 is right, but "some kinda mask" won't help significantly since those vapors will be heavy on ionized aluminum, unhindered by regular anti-dust masks.

lotzofgibberish. (author)antioch2015-06-13

What types of masks will be sufficient?

Ahnassi (author)2013-05-29

how much time the air blower will work before it overheats itself. is it enough to melt aluminium?

lotzofgibberish. (author)Ahnassi2015-06-13

The longer the pipe nipple, the more removed from the heat and the longer it will last.

thepelton (author)2009-04-15

Aluminum, when melted, is very oxygen hungry. Have you thought about how to prevent that?

If you're going to use a steel soup can as a crucible, you could open the top with one of those newer can openers that cut the entire lid off. I would also put a steel nail through the lid to make the crucible lid a little heavier as well as creating a small handle for the trongs to grasp.

nanoassembler (author)thepelton2009-10-15

 You can minimize oxygen exposure by covering the crucible. It willlimit the aluminum's oxygen supply. Just use something that won't beblown off by the air going into (and coming out the top) of the furnace.

Caveat: Every time you open the lid, the aluminum's oxygen supply will be replenished.
Solution: If you have to melt a lot of aluminum, cut a hole in the lid large enough (but not to large) toadd more metal as it melts in the crucible. Some oxygen will still flowinto the crucible through the hole, but it will be much much less thanwithout a cover.

sconner1 (author)2013-10-07

One could always sand or grind the zinc galvanizing off of the pipe nipple if you are worried about fumes.
I admit, Sometimes I weld galvanized parts together and can vouch that it is smelly and toxic.
Dust masks won't help.
It's better to not create the fumes in the first place, than to try not to breathe them.

sconner1 (author)sconner12013-10-07

Grinding the inside of even a short length of pipe poses a problem.
Looking harder or *Gasp* Asking for assistance finding the black pipe nipples may be the easiest fix. Or use copper which has an even higher melting point than steel.
Welders use copper "spoons" to back welds that are at risk of burning through.

patlicky (author)2012-04-02

can i use barbewue heatbeads or barbeque fuel instead of charcoal?

alexanderall (author)patlicky2012-10-03

just buy a bag of charcoal, its not very expensive and it is just alot easyer.. or you could just make your own:

babeh2011 (author)2011-09-14

Can I replace a soup can with a ceramic cup? Because as I know, ceramic can stand in extreme high temperature.

alexanderall (author)babeh20112012-10-03

you will need make sure that the cup has no air pockets in it otherwise it will explode...

flatcurve (author)2009-03-10

The slag is just the paint and PVC lining from the can (and crucible). Aluminum used in soda cans is actually very pure

cortchops (author)flatcurve2012-06-08

could you just sand the label off to reduce the "slag"?

ajhbriggs (author)flatcurve2012-05-18

the Aluminum in cans is very pure (though i'd believe that some oxidizes to slag as well)

BUT there are 3 very pure alloys: for the body, the top and the tab
each, separately, is high quality alloy- but melted together they make a much less useful metal

all those "recycled" aluminum cans we gather are actually "downcycled' in the worst sense of the word
-but with enough patience (or teamwork) you could take the tabs and tops separately, and use them for bicycles, airplanes and anything else aluminum your heart desires

chirman23 (author)flatcurve2010-02-22

I agree but you dont get very much for one can and it is easier to find scrap aluminum.

patlicky (author)2012-04-03

does this actually work?

patlicky (author)2012-04-02

does this actually work because i have tried alot of ways to make a furnace but none of those ways actually worked. So my question is does this awesome furnace actually work before i make it? Please reply :)

josh1324 (author)2011-08-27

Can you just line the walls of the furnace (on the inside) with mud/clay to make the can last longer?

curvy77 (author)josh13242011-12-19

mud would harden then flake eventully smothering the fire in dirt. clay could work however there is a chance of it cracking aprt. so be careful

Wiredfey (author)2011-12-16

Question, it's mentioned you use duct tape to hold the pipe on.anyone know if i'd be able to solder the pipe straight onto the hair dryer??

curvy77 (author)2011-11-18

thank you for your instructable! while i did not make the one u did it inspired me to begin my own forge. for mine was made of brick (not the BEST choice i admit but whatever) but i used your view in a small contained forge.

the pro (author)2008-07-15

i don't know much about metal works but so why do you need the forced air?

n0ukf (author)the pro2008-07-16

The forced air increases the heat of the fire, a forced draft rather than natural draft gives more combustion air to the fire. This is part of the same reason blacksmiths have blowers on their forges. As the coal cooks down to coke, it needs that draft air just to stay burning.

nutsandbolts_64 (author)n0ukf2009-05-29

u mean the oxygen?

n0ukf (author)nutsandbolts_642009-06-10

Yes, the oxygen is what makes it burn, but air is about 78% nitrogen and only 21% oxygen.

nutsandbolts_64 (author)n0ukf2009-06-16

if someone here came up with a way to make pure oxygen, please make an instructable on it. It will help w/ the smelter ( can it melt iron by blasting pure O2 into the fire ? )

easiest way is to use hydrogen peroxide from the chemist (you use it to bleach your hair) and then add chopped liver as a catalyst to produce a lot of O2. the higher the vols the more gas produced. If my basic school chemistry is not in error!

2k4u (author)strangebike2009-08-17

While meat and H2O2 will produce some oxygen, it's a very small amount. I saw that experiment in a science fair book. It would never produce enough O2 to fill a balloon, much less help a fire. Common drug store hydrogen peroxide is a mere 3%, which is pretty bad for most experiments...If you have a barber/beauty license, you can get around 10% for bleaching hair...if you find the right chemical supplier, you can get gallons of 20% - 35% for cheap. One of the best chemical ways of making O2 is decomposition of H2O2 by adding MNO2, manganese dioxide. If you can't buy some from a chemical supplier, you can take it out of zinc-carbon battery. But for hobby scale metal melting, you don't need any oxygen. It would likely get too hot and burn up whatever your foundry is made of.

hard2bme (author)2k4u2011-08-23

where do you put the zinc carbon?
right into the fire where the charcoal is?

Grey_valentine (author)2k4u2011-01-21

You don't need a beauty license to buy it. I have my cosmetology license but have never needed it to buy anything, and a barber, well they aren't allowed to do any chemical services with their license anyway. A beauty supply store not affiliated with a salon would be your best bet to pick up a lot for cheap.

strangebike (author)2k4u2009-08-18

yeah I knew there was a another chemical based way but couldn't remember it. thank you for jogging my memory. You are probably right lots of oxygen is going to make one hell of a pool of slag on the floor lol he he

wonder how you'll clean up the mess before it puts a black spot on the ground, haha:))

nutsandbolts_64 (author)2k4u2009-08-18

just wondering if I can use this on ceramic foundries.

n0ukf (author)nutsandbolts_642009-06-18

Pure O2 is very dangerous. Blacksmith forges use forced air (not pure O2) all the time to soften iron for working into the desired shapes. If you leave it in the forced-air fire too long, it starts melting/burning away. Just before you get to that point, the iron is just soft enough for forge welding.

collard41 (author)n0ukf2008-09-20
if you use it on cold setting the air is denser, and therefore you can get more airin the furnace at once and it will burn MUCH hotter
Killergunman (author)2011-04-03

Can u use wood vs coal?! plz respond asap

Killergunman (author)2011-03-27

is there a hole in the bottom of the coffee can? it kinda looks like it and can this be build underground like in a sand environment?

KyleHarima (author)2010-09-12

I would highly suggest not using galvanized metal on any surface of a forge. For I looked into the case of Paw Paw Wilson, who died heating galvanized metal.

tomtortoise (author)KyleHarima2010-12-02

what if i am far away and hold my breath when getting close

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