Introduction: Quick and Cheap Aluminum Melting Furnace Setup

Picture of Quick and Cheap Aluminum Melting Furnace Setup
This Instructable shows a quick and cheap setup to melt a few batches of aluminum for casting before the thin metal equipment starts to break down. Actually the 5-gallon bucket furnace will last quite a long time, over a dozen uses easily. This uses BBQ charcoal as the fuel and a hair dryer as the blower, it'll melt a small batch of aluminum in about 10 minutes. Most of the materials to build this can be found in dumpsters; the only cost here is the charcoal fuel, duct tape, and the $1 yard sale hair dryer. Recycle old lawnmower parts, computer/stereo parts, and beer and soda cans to make awesome new things with them.

For the furnace, two five gallon metal buckets (with lids) were used, a piece of 3-inch stove pipe, hair dryer, and of course, some duct tape.

For a crucible (the little bucket that holds the melted metal), a 16 oz propane bottle was used; the top was cut off and some bolts were added for grabbing the crucible with the tongs.

I made some basic tools with some scrap steel from an old bed box spring. You'll need tongs for the crucible, some kind of shepard's hook to tip the crucible when pouring, and a plain rod with a little bend at the tip for poking things and skimming out the dross (impurities in the aluminum).

Use of this equipment shown is dangerous because of very high temperature molten metal, fumes and smoke, etc. Use caution and be safe by wearing leather gloves, face protection, and other protective clothing. Do this outdoors and use it when it's a little windy so the smoke and fumes quickly dissipate, also use this during dry conditions because dripping molten metal on wet surfaces can cause little hot metal explosions (like water and hot oil in the kitchen). I'm not liable for any injuries you may occur using the equipment and techniques shown here.

Read, read, read lots of metal casting stuff before starting.

Casting Aluminum at
Home Foundry ...Melting and casting metal yourself

Here's a silent movie of the foundry at work.

Step 1: The Furnace

Picture of The Furnace

Using tin snips, cut a hole in the bottom side of one of the buckets to fit the 3 inch diameter stove pipe.

The hair dryer needs to have the "cold" button taped for use as just a blower; tape the hair dryer into the stove pipe, then insert the pipe into the bucket . Air flow is the most important part of this, I first used a little 1.5 inch pipe, but it just wasn't enough air volume to get the charcoal really nice and hot.

The bottom of one metal bucket is cut off about 2 inches from the bottom; a lot of holes are punched in center 6 inches of that piece and it's inserted into the main bucket as a burning base.

Keep the lids, one lid should have a 3 inch vent hole in it for burning and the other lid should be left unchanged for snuffing out the fire.

Step 2: Crucible

Picture of Crucible

This crucible might last half a dozen uses, but it's cheap and easy enough to make several of these.

Use a hack saw and cut off the top of a little camping propane tank (make sure its empty first).

Drill holes near the top of the cut tank for inserting some large bolts; these are for picking up the crucible.

Use a hammer and knock a pouring lip into the edge of the crucible.

Step 3: Tools

Picture of Tools
Tools, to make them you'll need a bench vice and some gorilla power bending skills. Just bend until things fit nice. Use something other than aluminum, like steel rod or conduit pipe.

These are the tools needed:

  • Hook tongs for lifting the crucible by its bolts.
  • A shepard's hook for tipping and pouring the crucible
  • A dross stick for skimming out the metal impurities.

Extra tools to have handy are:

  • Grill tongs
  • Large adjustable pliers

Step 4: Safety and Use

Picture of Safety and Use
  • Wear leather gloves, long sleeve non-synthetic clothing, preferably leather and thick cotton and leather boots, no flip-flops no matter how fun it sounds to have a hole fried into your foot. Also a hat to keep embers out of your hair.
  • Have a garden hose charged and ready for fires.
  • Work over dry dirt.
  • Have something ready to pour into; a mold in green sand for casting or regular dry sand when foam casting; many backyard casting people use steel muffin molds to make nice little ingots.
  • The first use of this is the stinkiest because of all the paint burning off the bucket and crucible, after that it's not so bad. It's best to do this on a slightly windy day.

To operate this, fill the furnace 1/3 full with charcoal and light it like you're going to cook some hot dogs. Wait until the coals start to turn grey on the edges, now fire up the blower and set the crucible in there with chucks of the aluminum. Cover the furnace with the vented lid, then grab a chair, a drink, and wait. When the aluminum is liquid, skim the floaties off the top with the hooked metal rod until the molten aluminum looks like a shiny pool of mercury. Now it's ready to pour.

Have all the safety gear on, turn off the blower, remove the lid and use the tools to grab the crucible and pour.

In the picture below, all my sand got wet just before I wanted to melt some metal, so I used clay kitty litter for a quick lost foam casting test . I don't recommend kitty litter; see all the lumps and pieces still stuck in the cast. Lost foam casting is using a piece of shaped styrofoam stuck in dry sand, then pouring in the molten metal which burns out the foam and takes its place.
Lost foam casting at

Have fun, I know I love it and will probably make a higher quality setup sometime.


TomOlsen (author)2014-04-29

You can make a longer lasting backyard foundry using a metal trashcan (I think it is about 20 gallons) for an outer wall, a metal 5 gallon bucket for the inner chamber, cheap unscented Kitty Litter (it is made of clay) to fill gap between outer wall and inner chamber (mix with water so it will pour like concrete, let dry thoroughly before using), some pipes and a blower for forced air, and an empty propane torch canister (make sure it is totally empty, fill with water & empty before cutting it to use as your crucible!), and charcoal as your fuel. You can scale this down, use the 5gal bucket as outer wall, large coffee can as inner wall. Just remember: Injuries from molten metal are PERMANENT! Molten aluminum can burn right through normal clothing and through your leg. So, BE CAREFUL! Do some Practice runs using sand as your "molten metal" so you are not surprised by the weights.

robbtoberfest (author)TomOlsen2014-04-29

Thanks for the awesome tip!!! I will be building a new one soon.

Steve MerandaH (author)2017-02-27

Super easy and cheap Aluminum can forge.

sean.rehak.9 (author)2016-09-18

I made one with a thicker concrete crucible and it didn't work. for a couple of hours it withstood the heat from a large bag of charcoal and a lid to trap the heat. mail came at that time and i threw the junk mail in and in a couple of seconds the junk mail burst into flames. i think my problem was a thick concrete crucible. will use an old fire extinguisher next time.

DH754 (author)2016-04-05

How'd you cut the hole for the stove pipe so neatly? Mine ended up being a jagged mess with a big gap when I put the pipe in. Also do you permanently attach it any way? (Like with glue or something.)

robbtoberfest (author)DH7542016-04-05

Draw the hole with a sharpie using the pipe as a template; then drill in the middle with your best bit. Use tin snips to cut pizza slices from the middle hole to the stenciled edges. Bend in the pizza slices and use them to attach small self tapping screws if needed.

wesley.jackson.75 (author)2016-02-17

this is exactly what I was looking for!, easy to build and disposable!
until I found your instructable, everything I had found online was way too elaborate for my first run at this.
I am beyond excited, I cannot wait until later this evening! I spent last night tearing heat sinks off some old PCBs that came out of old stereos, dvd players and VCRs (great source for aluminum.)
great write up, btw...appreciate the advice/reminder on wearing PPE.
I'll let you know tmrw how it goes!

I'm glad this will work for you. My only recommendation is to add some type of insulation; the heat loss is high but tolerable.

Izzypup (author)2016-01-07

Loved your 'ible but didn't understand (or missed) the purpose of the second can. Am I right in my thinking?....starting from ground up - bottom of large can/barrel, next a void into which the blower system is inserted, next the smaller can with holes in the bottom, next the coals and the crucible? Or does the charcoal go between the 2 cans along with the blower and the crucible sits on the bottom of the smaller can?
Also, do you skim the top of the molten liquid thru the hole in the barrel lid or do you remove the lid? I'm trying to imagine trying to see what needs to be removed while looking directly at a brightly glowing fire and around my gloved hand and the skimmer!
PLEASE (everybody) forgive my ignorance, but we all have to start somewhere!

robbtoberfest (author)Izzypup2016-01-10

The charcoal burns on a little shelf made by the second bucket (with holes drilled in it) upside down inside the main bucket; the air blows in from under the charcoal.

The crucible nests in the charcoal.

I remove the lid when working with the molten metal; if it looks like floating 'dirt' on top of the liquid metal, that gets skimmed.

Good luck

nicolo86 (author)2010-08-08

How much aluinium a beer can gets you. Great instructables !!

DavidJ55 (author)nicolo862015-08-30

It takes around 38, 12-oz cans to produce a pound of aluminum.

WhiteP (author)2014-09-27

okay, once the aluminum is melted.. what can I pour it into for a bar shape?..that will put up with heat and keep its shape.. and I need to know a little on the cooling process, as in when it's safe to grab and such.

DavidJ55 (author)WhiteP2015-08-30

Check Amazon for graphite molds in bar shapes.

JessV1 (author)WhiteP2015-03-04

Well then. You'd just get steel or something else with higher melting temperatures. Typically you see people just using a stock bar imprint of steel or little nugget molds.

afridave (author)2015-08-21

can plaster of paris mould be used to cast this moulten aluminium into?.....i would imagine they would deteriorate rapidly due to the heat...anyone know any adjuncts to add to plaster of paris to increase its heat resistance/durability....oh and if you try using plaster of paris make sure it is well and truely dry.....kaboom otherwise

DavidJ55 (author)afridave2015-08-30

Don't use plaster of paris - it will not hold up at all. Plaster of paris, mixed with sand, is fine for a temporary refractive material for the inner lining of a furnace but liquid aluminum will go right through it upon contact. If you absolutely need the fine-grain resolution that a plaster mold would give you, consider silicon or even very fine green sand.

shana.whitesides (author)2014-10-22

How can I make a furnace to work on a larger scale? I am talking about having enough aluminum for large projects ( at least 16"x20"x18") but some projects are larger. The small one just won't last long enough or melt enough metal at a time.

JessV1 (author)shana.whitesides2015-03-04

That's a lot of aluminum, make sure your furnace is actually hot enough to make sure the center of the aluminum is as hot as the edges! Suggestions to break a larger project into smaller ones would be making aluminum chunks that fit into each other through a series of tight bars and meshes. Or when you cast them you can add a center to your mold so the aluminum makes a thick shell around the outside (your required strength) but you save tall the aluminum that would've been in the center.

WhiteP (author)2014-09-27

and what did you use for the bolts on the old camping propane tank, and how did you cut it open.

Thanks (author)2010-11-28

I want to use a clay mold and make a sword prop, but aluminum isn't strong enough on its own, do you have any recommendations for other metals to add.
Also could I use crushed pop cans, trust me I have enough.

Snidely70448 (author)jj.inc2013-12-15

Copper. Aluminum bronze is very srong


TheIntelligentOne (author)jj.inc2012-06-10

Personally, i would recommend a 15% copper (Pennys or Cents), 10% steel (if not available, stainless steel old cutlery or 10% zinc) and 75% Aluminium (cans of pop)

This should create a stronger metal mix.
I wouldn't recommend it but i suppose you could add 5% gold.
(I get my gold by panning in North Wales, UK) (author)TheIntelligentOne2012-06-15

I am not sure if I should take you seriously because I don't think steel and aluminum alloy together well.

crazypj (author)jj.inc2013-09-17

Aluminium will dissolve stainless steel, even though it melts about 1,800 degrees lower temperature
Stainless is good when your scratching surface of aluminium to remove oxides but if you try and weld the stainless will bond extremely well I'm guessing you won't need to ask how I know ;)

Do you mix by volume or weight when making alloys?

Well... i think it depends but i was told you mix by volume as mixing by weight may not be accurate as the material may be lightweight

AJMansfield (author)jj.inc2012-05-21

Add zinc to it to form a Zamak alloy.

AJMansfield (author)AJMansfield2012-05-21

Though you'll need to look up what the exact proportions and stuff are for the best blend. Also, doing it this way you will only need about 600 degrees, while raw aluminum only melts at a thousand-some degrees.

robbtoberfest (author)jj.inc2010-11-29

You'll need a stronger furnace to go hotter and use some other metal like steel. Pop cans are aluminum. (author)robbtoberfest2010-11-29

Yea, I should have re-ordered it, I meant I could use the pop-cans for the aluminum. Steel is expensive, do you think it would mix with the aluminum in a hotter furnace. Maybe add the steel once the aluminum has melted using an oxyacetylene torch (hot metal cutting torch, will probably boil metal

andygreene (author)jj.inc2011-09-22 Maybe you could use a piece of small diameter re-bar as the center of your mold piece. Maybe make it out of wax around a rebar core, and pour the AL down in the mold. The AL might form around the steel core, gripping the ridges on the rebar.

That would give you strength.

robbtoberfest (author)jj.inc2010-11-29

Dude, that's way over my head; you're getting into the world of metallurgy and need the advice of skilled people for that. Mixing metals is tricky work.

Aluminum and steel will not bond with each other. Melting temperature is far greater for steel, not to mention, you would be melting the crucible in the process as well. You should try casting with just the aluminium, you will problably be surprised how strong it is. Other than that, creating an aluminum alloy would be unpractical, expensive, and highly inefficient., rather than buying the prop.

immy007 (author)2013-07-13

Hey Guys
I wanna manufacture Air condition aluminium grills by melting and moulding the the grills shape can any one help

justicious (author)2012-05-07

I read on another forum that the aluminum will get stuck to the muffin tin is this true?

OrlandoArtist (author)2012-04-08

I like this instructable a lot; practical, easy, cheap...up and running in no time. With a bounty of discarded scrap people regularly throw away (found a perfectly good, heavy aluminum CO2 cylinder today!), this is virtually a free hobby. More info on mold-making would be very useful; though I'm sure there's plenty out there. Thanks for doing this.

patlicky (author)2012-04-02

oes this actually work before i make it?

robbtoberfest (author)patlicky2012-04-02

Yep; its a very low-effort build for melting aluminum.

sinkerman (author)2011-10-24

the little red hand held dirt devil vac's make a good blower . can be got at yard sales cheap . broken belts don't matter . you can use a cut down 30 gl drum and the 5gl bucket inside with mortaland firebricks inbetween for instulation will heat faster and hold the heat . make yourself a set of arm sleeves from a old pair of boys jeans cut off leggs and wear onyour arms for protection from heat and splashing molten metal

robbtoberfest (author)sinkerman2011-10-25

Nice tips, thanks. The firebricks are a good addition; this design loses heat rapidly.

andygreene (author)2011-09-22

Don't use any galvanized metal for making any of your foundry tools or equipment. When heated or melted, it can give off toxic fumes. Very very bad.

Awesome instructable, along with your tile making dye/stamps! You rock!

corkey123 (author)2011-05-25

NICE! Just what I needed. Thanks!

arirang777 (author)2009-04-20

okay, how did you get the mini "propane" camping tank opened up? Obviously it was empty, but still it may be a hazard to use a saw to open it. What's your trick? Thanks in advance!

jack8559 (author)arirang7772010-12-12

most of the small tanks have a valve that you can depress letting all the excess propane out... similar to a valve in a tire.

robbtoberfest (author)arirang7772009-04-21

I put the tank in a vise and used a hack saw, no sparks or anything. Beware of the residual propane stink.

Firestorm_101 (author)2010-09-30

How did you attach the bolts to the crucible? I'm not very wielder savvy..

Drill holes in the side of the pot and just put the bolts in there with nuts.

knektek (author)2010-09-28

W00T! My DT teacher was like this stuff needs to be shipped all over the world just to be metled. And cuz he's long he went on about the gulf of mexico oil spillage....

About This Instructable




Bio: Dad and hubby, good food enthusiast, solar energy, boating, making stuff, melting stuff, and raising chickens.
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