Ultimate Guide to Making a Cheap but Effective Aluminium Forge.

There are many guides and many ideas I've collected and, being that I completed this (the first one... I made a completely new setup just for this instructible... you should feel special.) within two days and most importantly... cheaply.

My cousin /assistant / camera man and I created this instructable so we could share our wonderful smelting smelting experience and win the hearts and minds of the instructable community.


This instructible includes fire and molten metal.

Also; If you mortally wound yourself while duplicating this instructible, please delete this from your history internet history before dieing. i don't want to be held liable.


We shall begin.
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Step 1: Parts / Tools

In retrospect, the parts / tools list quite long but it should be things that are easily available.

The most expensive thing was the torch. I'm really cheap but it turned out to be a rewarding investment.

The other parts are as follows:

Quick Setting Quickrete (I got a 20 lb bucket for under 10 bucks)
Something to mix the Quickrete in
Something to stir the Quickrete with
Large Coffee Can (6 inch)
Small Coffee Can (4 inch)
Hack Saw (or any metal cutting tool)
Drill (or metal punch or improvised hole making tool)
An empty 14.1 oz propane tank (make sure it's competently empty)
Scrap steel bar like from a printer, about a foot long (you can buy 5/8 steel bar at lowes)
A sharpie (or any marking tool)
Short (about 2 or 3 inches) iron or steel tube that the torch head fits in. (optional)
A ball peen hammer (any hammer will suffice)
Some propane gas (i buy the ones for camping stoves because their $4.38 for a 2 pack of 16.4 oz tanks.)
An oven (optional)
A vice. ( kinda optional. you could find another way but i find the vice necessary)
A mini muffin tin (optional. you just need something to pour the aluminum into.)
Some cheap thin steel wire (1/8 diameter max. but strong enough to hold some weight)
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Mgr1216 days ago
Wow this post needs to be taken down these meathods are extreamly dangerous and not to mention forgeing aluminum or magnesium can cause parkinsons deseise and cancer and if its an alloy with zinc it can stright up kill you with out proper ventalation and charcole respirators this is dangerous only safe metal to forge without need of a respirator is unleaded iron and steel
WWil Mgr124 hours ago

So what can I do to be safe while doing this? Could I just wear a ventilation mask and be fine or is there more?

TenKTech Mgr1215 days ago

If we treated all information like that then this would be lost over time and only corporations would know how to do it. Responsible people use the internet to further their skillsets and education as well.... If your argument is for kids then that's a parenting issue not anything else...

Mgr12 TenKTech15 days ago
And also the reply of "responsible people use the internet to further thier skill set" is just ignorent any one can see this post no matter their age, resposiblity, or level of common sense... Not only smart responsible people that know all about the dangers of metal working look this up, in fact i believe there is more of a tendancy for people that have no clue how to do it thats going to look up instructions, than there is people that understand
Mgr12 TenKTech15 days ago
How is the potential to give a teen a life altering problem a parenting problem? Im not a parent and wasnt looking at it from that standpoint but its good you brought it up kids do things without thinking it through and the propane tank in this post is extreamly dangerous to thoes that dont take precautions, there are also adults out there that would like to do this that also do not know the dangers of breathing in the fumes, i wasnt suggesting it be took down because you shouldnt do it but because it doesent tell people the dangers and how to protect themselves, i too looked this up to further my skill set but if i didnt already know the dangers i would have done this as it was in the instructions and could have seriously harmed my health by doing so and im sure there are others that probably have done the same
IronM227 days ago

I made this, based on another persons build. Worked great... actually... mine worked too good. We accidentially melted the STEEL propane tank used for melting the metal. So apparently I need a better crucible.

Azazel891 month ago
Awesome instructable

The one thing that caused some concern for me was cutting into a pressurized container. Even though you make sure it's empty. I've seen tanks explode just be careful is all.
In other words use fire extinguisher not water.
"Mixing water or other contaminants with molten aluminum can cause explosions. Explosions can also occur in the aluminum scrap re-melting process due to moisture and contamination in scrap."-See more at:
Warning! Use fire extinguisher, not water! Aluminum is explosive! Keep it away from water! See this page:
sheddk3 months ago

As far as a propane tank crucible:

1: make sure tank is empty.

2: make sure tank is empty


a: light a small camp type fire

b: have a protective barrier pre set

b1: Make sure you understand b: then place tank in fire

c: walk rapidly to protective barrier (b:) 10 yards+

d: get a gun and fire a round through top of propane tank

e: fire 2nd round at tank if any doubt 1st round hit

f: retrieve tank (retrieve next day if unsure of first 2 rounds

f1: Shoot another round next day

g: Finally, cut tank as you see fit

3: Foot note for pros:

Try with full tank, but double distance to protective barrier and have "friend" place tank in fire. Results......impressive, but don't expect a usable crucible via this method.

4: COME ON PEOPLE...if unsure of any steps required to do any of this safely DO NOT ATTEMPT. Once Forge is built the true danger shows up. If concerned about have to far to go to MELT METAL safely. Fumes, heat, reactions via moisture or chemicals, gas build-up, splatter, slag, fire, burn through, etc......molten metal is easy to achieve, what to do with it once liquid, that is the true danger. Good luck all.

mrjackson sheddk2 months ago

Taking the valve off then filling it completely with water is another good way of verifying that all the gas is out and it's safe to cut.

dion.fettke4 months ago

question -- what would happen if you mixed fine glass powder smaller then sand with the molten aluminium and mixed them together why'll the aluminium is in liquid form

is their a chance of EXPLOSION or will it just make the finished product brittle pending on the amount added

Sort of going off ash springer, the explosiveness in thermite is all about how readily aluminum oxidizes, and the heat that is produced from the reaction. You'd have to do an energy balance to figure out whether there is an energy deficit or increase. Keep in mind there is a lot of free energy in molten aluminum.
In the case that the oxygen molecules from SiO2 don't explosively move to the aluminum molecules, you'd still have a really brittle product - I guess thats what you want, so it might be worth a try.
Definitely do the energy balance though to evaluate the risk..Then post the results up here! Sounds like an interesting idea. Whats the goal in extra brittle aluminum? b/c another solution is to just leave the melt out and oxidizing or restir the dross back through the melt.

GOOD POINT ! i think there is a chance not of explosion but of intense thermic reaction perhaps , which may well end in explosion my pyro chemistry is not my area but alot of pyro based products are made from aluminium flash powder for example now silicon dioxide may well make a thermite when mixed with powdered aluminium but im unsure because both will be in liquid phase whether there would be enough surface area to cause a reaction as one would expect liquid silicon dioxide and liquid aluminium + tin + byproduct annealing products, to all be very different in density and not mix well (you avoid agitating the pot while smelting alli) the sodium lpercarbonate used to seperate off the label junk and tin impurities adds another possibility. thats not an answer just my thoughts evoked by your statement, try it why not but be very careful as thats a very big dangerous cherry bomb if what you suggest happens.

joshmayo7975 months ago

I have a question for you.. Do you think A home made coal forge can be made out of aluminum? Minus the fire pot of course.

I don't think so. I think it would be unsafe to construct the forge out of anything less than iron/steel. The inner surface should be refractory cement (or firebrick) as well. Aside from the risk of overheating the aluminum, the stability/strength of the iron is desired.

flyman4161 year ago
Hi I really the idea of this cuz I've been thinking of what I could use as a crucible in my forge and I saw this. I was wondering how do you make sure the butane tank (the one that will be the crucible) is completely empty? I showed my dad this and he was like "NO!", but I wasn't about to cut into a pressurized tank like that. We have an "empty" tank but I'm not sure how pressurized it still is. So how do you depressurize it?

best way is to hook up the torch head to the propane tank your going to use and hold it under water. if bubbles rise from the tip then it still has pressure, if not then you should be fine. i am not liable for stupidity though

billjoh6 months ago

Just a idea to make your forging much easier. Check this out from Budget Casting supple. Also I have been a mason for over 40 years I know first hand that fire and concrete don't mix, I would never put a flame to concrete. I have built hundreds of fire places and masonry smokers and grills.Get a book on green sand molds you can't get any cheaper than making your molds from sand. Good source is Lindsay Publications Inc. Bradley IL.

I copied this from Budget Casting Supple.

A crucible is
needed to withstand the extreme temperatures encountered in melting
metals. The crucible material must have a much higher melting point than
that of the metal being melted and it must have good strength even when
white hot.

It is possible to use a home made steel crucible to melt metals such as
zinc and aluminum, because these metals melt at a temperature well below
that of steel. However scaling (flaking) of a steel crucible interior
surface is a problem. This scale can contaminate the melt and thin the
crucible walls rather quickly. Steel crucibles will work if you are just
getting started and don't mind dealing with the scaling.

Common refractory materials used in crucible construction are
clay-graphite, and carbon bonded silicon-carbide. These materials can
withstand the highest temperatures in typical foundry work. Silicon
carbide has the added advantage of being a very durable material.

Our Clay Graphite Bilge Shape crucibles are rated for 2750 °F (1510 °C).
They will handle zinc, aluminum, brass / bronze, silver and gold
alloys. The manufacturer states they can be used for cast iron. Made in
the United States!

The "A" shaped crucibles are useful for metals up to 2000 °F (1093°C).
They will handle zinc, aluminum, brass / bronze, silver and gold alloys.
Made in China.

The Silicon Carbide Bilge crucibles are rated for 2750 °F (1510 °C).
They will handle zinc, aluminum, brass / bronze, silver and gold alloys.
Made in Mexico.

billjoh billjoh6 months ago

Oh I forgot that you can buy a crucible from Budget Supple for as low as $22.00

Seem to me you would be better off buying one than making one your self. at such a low cost and you would get better resuilts from your forging.

samuri098 billjoh6 months ago

Which of the three crucibles would you prefer?

And what other materials would I use to do a aluminum anthill project?

jdgreen8 months ago

MOLTEN METAL AND WATER DONT MIX!!!!! Also make sure your muffin tin is steel... i had an aluminum one which i quickly discovered after trying to pour molten aluminum into it.

justin557 years ago
im not sure exactly what the cause was but last weekend i had a propane torch and i decided to heat a penny with it and discovered that it melts, then i did it on my wet carport and it exploded all over my face and it looks like i scraped up my face really bad, i could have been blinded easily and i recommend being very careful with water!!!!!!!!!
jsyson1 justin559 months ago

Glad you're okay. Basically, as soon as the molten metal got in contact with the water/moisture it turned it to steam almost instantly, that expansion (volumetric ratio well above 1:100) is what sent the molten metal flying upwards. Again glad your okay, especially your eyes. There is a very good reason foundry workers get around in all that protective gear...

It's the same reason that you don't place water onto a grease fire. The water rapidly (very, very rapidly) turns into a vapor. When it turns to a vapor it expands and moves outwards. In the case of a very hot liquid, the water turns into water gas and pushes everything outwards. There is no need for a chemical reaction. Rather, the physical transition between phases is what causes the explosion.
actually if the grease or oil is hot enough the water decomposes into hydrogen an oxygen instantly ignites and creates a huge fireball might look cool but is very dangerous
Water decomposes into hydrogen and oxygen around 3,000C. Then plasma incineration. Cooking oil (such as canola) top out around 500F. So it is simply a phase transition. As a solid or liquid transitions to a gas they expand and occupy much more room. When this transition and expansion happens very quickly it is termed as an explosions. A bomb undergoes a chemical reaction that gives off heat and gas at the same time which makes it occupy more room very quickly. Gundpowder is a great example. Just a tiny bit can hurl a tank shell for miles. Water thrown into a 500F fire immediately and rapidly expands into a gas. This transition throws oodles of burning oil into the air. Not a lot of fun to be around. But no chemical reaction is necessary.
some pennies melt because at some point they started making them out of zinc (someone correct me if I'm wrong) that explosion was probably the concrete exploding underneath the molten metal when it was heated, because there is still small amounts of water in the cured concrete...when you heat it, that water turns to steam, creating lots of pressure, eventually it explodes due to built up pressure , thats why you use so little water in the cement when you make this furnace, you also have to ram it in to eliminate any air pockets.
In 1982 they switched from basically pure copper pennies to copper coated zinc. In fact, pre-1982 pennies are worth more as scrap copper than they are as pennies.
1944-1982, US pennies were 95% copper. 82 and newer are a zinc blank, with a copper wash.

Wikipedia on Pennies

WesDoesStuff (author)  Jonny Appleseed7 years ago
well put
WesDoesStuff (author)  justin557 years ago
ya probably shouldn't have done that. ; ) chicks dig guys with scars. be safe, be well, and thanks
hahah true that, Hockey player here. split my chin open 4 times now. 9 stiches each time. funny thing is, i didnt realize i cut it till the EMT came up to me and was like, your going to need stiches. i looked in his mirror and i had blood all the way down my neck. happens evrey time.. i still get some hot *** biznatchesss
jsyson19 months ago

I work in a iron foundry, and I can't stress this enough: KEEP WATER AWAY FROM MOLTEN METAL.

Furnaces can, and do explode due to molten metal + water. Not just a pop, they can literally explode and rain down molten metal. people have been killed by 2 ton furnaces exploding, google it! Molten metal turns water to steam so fast, it expands in a flash, and can send molten metal flying.

I see these warnings below from people in the industry being dismissed by people without experience - I don't understand this, WHY do you think he is commenting?

Not to mention that aluminium is more dangerous, even though it has a lower melting temperature, it reacts (chemically) a lot more dangerously than say iron or steel.

jsyson1 jsyson19 months ago

Might I suggest a bucket of sand as a safety measure instead of water. Much better idea...

As far as improving this little furnace goes: Why no lid? Heat rises, and that's where your going to loose most of your heat. Get another tin the same as the bottom, cut it to 1.5" tall, add a 1" vent hole at the top, and two slots for the crucible handle to come out of, then form the refractory (concrete lining) as you did on the bottom.

Also important: LET RECRACTORY COMPLETELY DRY BEFORE USE. Fire the furnace up on low heat and increase over a few hours to set and harden.

Vise, not vice. Vise is for holding things, vice is for having forbidden fun.

LMAO forbidden fun.

captainjaneway10 months ago

Hey, I cut into the propane bottle using a simple metal cutting blade on a hacksaw. Just make sure that when you are cutting into it the tank is empty and has NO pressure. Pressurized propane even when not exposed to sparks or flame is still dangerous as it is a pressurized gas and is pretty cold. You definitely don't want to use a torch to cut a bottle in half. I haven't built the kiln yet as I don't have a torch that will cut steel. I will have to use cold cuts unfortunately.

dschwab11 year ago
My father has run a propane business for years, If you are going to cut into a propane tank and do not have any experience i would recommend not doing it.

IF you are going to I am not liable for this advice :P

Drain the tank completely.

Use the stock equipment to leave the gas on once its out and tip the tank upside down, since Propane is heavier then air. We leave ours for 3-5 days like this. Some smaller tanks like torches or camping grill tanks have a port on the side that I have had in the past, used a tool for removing the core from a tire valve air input, to remove from the tank and also help drain.

After that we then fill the tank with water to disperse ANY leftover gas included air which again can be combustable in certain environments.

after these steps almost but not all risk has been reduced but you still should consult a proper propane specialist.
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