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)

Step 2: A Suitable Crucible

So I took the empty 14.1oz and put it in the vice.

We used my hack saw to cut just under the seam then de-burred the edges.

If you look at the bottom you should see 4 holes. Use a marker to draw a line up the side in line with a hole.

Use the ball peen hammer (or any hammer) and bang out where the line is. This will make a spout. (may take a little working to get it right but as long as it's there, pouring will be easier)

Now draw lines up the sides from the holes adjacent from the side with the spout.

About 1/4 inch from the top, mark the line, and drill at that mark on both sides.

I used a drill but anything number of things could be used.

Make sure your metal bar fits in the holes.

Put on a pair of leather work gloves.

Now mark the center of the bar.

Heat it up over the torch.

When the metal turns red, bend it in half to make an acute angle but not completely in half. (see picture)

Quench the metal in some water and heat up the ends one at a time. Bend them in so they face each other.

Quench the ends and re heat the center bend. Unbend it and rebend it so the ends that you bent in fit into the holes in your half of a propane tank.

Quench the center bend and ensure that your new handle moves freely in it's holes.

You are now the proud parent of a crucible.

Step 3: The Forge

This is kind of difficult but has few steps.

Cut a hole in the side of the big can about an inch from the bottom.

Make sure the pipe fits. (you could use a piece of rolled up paper or cardboard.)

Use a can opener on the bottom of the small coffee can and cut a mouse hole shaped hole in the lower side. (make sure the pipe fits)

Wrap the small can in cardboard. (this is to make it easily removable.) and cut out the mouse hole in the cardboard.

Mix the quickrete. We used 11 cups of quickrete and about 2.5 cups of water.

Pack the quickrete tightly in the bottom of the can and up to the bottom of the hole.

Place the pipe in the hole and the small can in the big can with the pipe in the mouse hole. Try to center the small can.

You want the pipe to go in diagonally. This will help create a spiral of flames. (see picture)

Fill up the sides with quickrete and pack tightly.

We let it set for a bit then put it in the oven and set it to 400.

After 30 minutes take it out and pull out the small can and the cardboard.

Put it back in the oven for 2 hours. This will help eliminate the moisture.

Use oven mitts and take it out of the oven. and bring it to our work area.

Lite the torch and stick it in the pipe.

I suggest wearing eye protection.

This first firing is just to eliminate moisture. You may see steam coming from the cement.

Let it fire for about half an hour then let it dry overnight.

We put the crucible in during the first fire to help burn off the paint.

Step 4: Melting Aluminium

This is pretty much the most dangerous part so have water near by and wear thick leather or welding gloves as well as safety glasses and make sure the area is well ventilated.

You're going to want to fire it up and put in your crucible.

I'd wait until the bottom of the crucible is red hot. (just a personal preference.)

Start out with small pieces of aluminum. (I had "pipes" from an old wind chime.) You could use cans but they tend to have a lot of slag. I'd wait until you have a nice quantity of aluminum before using cans.

You'll probably have a rough start so go slow. After you get a good quantity of aluminum it will be able to maintain a melting temperature and you can melt down large pieces in seconds. I have found an old knock off of a razor scooter in th back of my garage that has worn out it's usefulness. I found a new use for it's aluminum.

I have found covering the crucible with the top half of the empty propane tank helps keep the heat in and keeps things moving along nicely.

I had a troublesome piece of scooter that didn't want to release it's steel screw so I dunked it in the pool of molten madness and that half didn't come back. A mallet made short work of the obstructing piece of metal and allowed us to make a deposit in our crucible.

After you either fill up your crucible or run out of aluminum, you need to scrape off the slag. The slag will be floating on the top and will look a little different than the metal underneath.

We used a scrap piece of metal to scrape off the slag. We used the same scrap to make a hook to pick up the crucible and another piece to fit in the holes on the bottom of the crucible so you can easily pour it. You could use a small screw driver for this.

Make sure you have something to pour the aluminum into. I am just going to save them for later so I'm pouring them into one of those "mini muffin" tins just because they're small and fit in the crucible. You could just use an impression in wet sand or something. Muffin tins are faster. But don't expect to use them for muffins again.

Pour gently into the mold of your choice. IT IS HOT! WEAR PROTECTIVE EQUIPMENT!

Because I'm impatient, I wait until the aluminum in the tins are solid then throw them into a can of water. The water may boil violently after a short delay. It is a sight to behold but dangerous.

You now have aluminum ingots.

Step 5: Now What?

We now have a lot of ingots. You now can use the rest of your free time planning on how to get a hold of a harbor freight micro-mini-lathe for $250.

I figure we could cast some blanks that can be worked in a tiny lathe but that's for later.

We'll Make an instructible on casting aluminum when we get it down to a simple science.

We hope you enjoyed this instructible and happy smelting.

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    497 Discussions


    5 months ago on Step 5

    My favorite part is where you instructed people to use a wet sand mold for the aluminum , hope none of the people suffering burns from exploding aluminum sue you


    2 years ago

    Go on YouTube and "grant Thompson, the king of random: aluminum forge. He makes a great video on how to safely do this.

    1 reply

    Reply 2 years ago

    If I may correct myself, the video is called: mini metal foundry


    3 years ago

    Just because you took a hack saw to an "empty" propane bottle and you weren't injured doesn't mean it's safe, or a good idea. I would think very carefully before advising others to try something like that. There will always be propane vapors left in the tank. Every time is a roll of the dice.

    2 replies
    Dennis R Levesquehellzwells

    Reply 2 years ago

    It seems to me the best way to ensure it's really empty is to attach an appliance (torch head, cook burner, heater, etc.) to the tank and open it up to expel the fuel.

    If you wait until the heat-of-the-day to close it, then cut the tank at night, there will actually be a vacuum in it. A hack-saw will not produce sparks, (just don't use a grinder on it), and cut it slowly. I've never had a problem.


    Reply 3 years ago

    You're absolutely right. A good idea is to find a tank where you can unscrew the nozzle and then purge the remaining gas by first filling it with water.


    3 years ago

    Obviously, safety first - or at least a solid third. It's molten metal after all...

    A little late to the post. So I've had a very similar foundry made for a while now made of Quickrete surfacing mix and sand in a steel bucket. It's also a solid fuel foundry (charcoal briquettes) with a small electric air mattress pump for air supply. Melting down aluminum is easy enough and for the price of a bag of charcoal, I can melt down 15-20 pounds of aluminum cans. Temp runs between about 1100 and 1900 deg F depending. If I cover the foundry (quickrete/sand cover a couple inches thick with a vent hole in the center) it will soften steel enough to cause a failure.

    The problem for me has been the crucible. Tried steel milkshake tumblers. Failed about 20 cans in. Tried small empty fire extinguishers cut down to height. Failed after one or two pours. Haven't tried an empty propane bottle yet. I imagine they are about the same thickness as an extinguisher? Can anyone report how long these last for? If these fail, next will be schedule 40 stainless pipe with a welded bottom plate. Be cool if anyone has a lead on something similar...

    3 replies

    Reply 3 years ago

    I took the top of a fire extuingsjer that I thought would be the perfect crucible.

    Fire extinguishers are often made from aluminum. They can do this since the pressure is very low, the gas used is safe, and the content is (obviously) non-flammable.

    Propane is under much more pressure than the extinguisher, and being flammable even explosive has certain legal requirements, one of which I imagine is requiring either very thick aluminum (not economic) or using a stronger metal like steel.


    Reply 3 years ago

    I have used a fire extinguisher cut in half for 20 bags of aluminum cans. Hasnt failed yet. I started with charcol to hear with hair dryer blowing my air. Moved upto a propane torch. I purchased a graphite crucible for copper and am buying a larger one for aluminum. They are on amazon.


    Reply 3 years ago

    YES! same...stupid...problem...solution:1/4" black steel pipe with an end cap. 1-1/2" OD i think? 'bout 4"-4.5" long.

    my brother-in-law throws boxes in a warehouse, and has on occasion moved empty industrial sized dumpsters 10ish feet across asphalt (we were at the beach and he REALLY wanted that parking space...)his strength is legendary in our circle of friends... I'm a shrimpy dude...

    he grabbed one end in a pipe wrench, I grabbed the endcap in another pipe wrench, and we pushed in opposite directions, with all our might...i got pushed around the room... it has never leaked, has never split, broken, or warped...has processed probably about a hundred melts over 3 years of abuse... it's got some nasty scale on the outside, and it sucks to clean... but we can still wrench off the endcap, clean it, and the threads still meet back up when we put it back together. and we've had it glowing dull orange quite a few times!

    only real downside is that with so much steel, it really sucks a lot of heat... but it also holds a lot of heat when it DOES get hot, which is nice if you need to do a bunch of back-to-back melts.


    3 years ago

    Thank you so much i have been wanting to melt down some metal and smelt and this helps me alot thank you


    4 years ago on Step 4

    I am melting cans and find a lot of slag in the aluminium melt,what can I use to float the slag off and what can I use to degas the aluminium.

    2 replies

    Reply 4 years ago

    I use a spoon of char coal ash and a spoon of rock sea salt . they act as Degassing agent and flux . the salt you get at the food isle at the store.


    Reply 3 years ago

    I hear using a salt substitute like no salt is a much better one to use. I bought a 2 pound bag of borax i also heard works well. Im going to try on my next batch. I have 10 bags of cans ready to go. Just looking for a day its not 100 degrees to work.


    4 years ago

    Well I plan to make one of these but my question is, after you pour the aluminum into the muffin tins, how do you get them out? I know this may sound stupid so please ignore my ignorance.

    3 replies

    Reply 3 years ago

    I dont even tap mine. The molten metal doesn't stick. I take the garden hose and spray it over the top until the steam and hissing stops. Then use tongs to pick them out or dump them into a 5 gallon bucket of cool water.


    Reply 4 years ago on Introduction

    Move the tray onto a well-cured concrete pad or some rocks and spray the bottom with water. The muffin tray will be red hot so be super careful as it will steam and pop. Just keep putting water on it and once the bottom cools, spray some on the top. Eventually, the aluminum will shrink and you can simply turn the muffin tin upside down and they will fall out.


    3 years ago

    Hi to Everyone,

    Regarding the safety issues related to this and numerous other posts...... I think anyone that takes instructions directly from a post on the internet without thoroughly researching the project and safe practices related to that project should be a poster child for Darwin's theory of evolution. People forget that the #1 cause of death in humans is not heart disease, cancer or any medical condition.....It's STUPIDITY!

    Dumb Kills!

    1 reply

    Reply 3 years ago

    Its their choice to be stupid.