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.

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Step 1: 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

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

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

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

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.

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    139 Discussions


    1 year ago

    This is way easier than the king of randoms lol


    3 years ago

    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.


    4 years ago on Introduction

    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.

    3 replies

    Reply 4 years ago on Introduction

    "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.


    Reply 4 years ago on Introduction

    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.


    Reply 3 years ago

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

    david foeckler

    3 years ago

    How long does it take to melt the aluminum?


    4 years ago

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


    9 years ago on Step 5

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

    3 replies

    Reply 7 years ago on Step 5

    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.


    Reply 7 years ago on Introduction

    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.


    6 years ago on Introduction

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

    1 reply

    Reply 4 years ago

    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.


    Reply 10 years ago on Introduction

     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.


    6 years ago on Step 5

    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.

    1 reply

    Reply 6 years ago on Step 5

    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.


    7 years ago on Introduction

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