Introduction: Blow Dryer and Red Brick Aluminum Forge

A charcoal forge for casting aluminum electrodes and casings can be made from a blow dryer and some clay bricks. Aluminum scrap comes in a variety of forms, mostly involving impurities of one form or another. This scrap can be reduced to (more or less) pure aluminum oxide (what we commonly call aluminum is actually aluminum oxide) by smelting it and removing the impurities which float to the top. The molten metal can then be cast into forms which are convenient for use in low and medium voltage al-air or al-oxide energy generation systems as well as other casting applications.

Unlike many other forges this one can be reasonably used in a residential environment without attracting undue attention from the neighbors. It's not particularly noisy and doesn't project huge fiery jets. It doesn't require permanent construction or a specialized installation. It can be put together, used and torn down in a single afternoon.



I really like many of the propane designs I saw but most people don't have a propane burner or nozzle assembly to spare so I decided that design which leveraged existing BBQ technology would be more widely useful.

The mandatory note: I believe the insurance company add that says 25 burned down their houses attempting to deep fry turkeys. Don't be an idiot.

No blow dryers were injured in the making of this instructable if would be nice if folks who tried this exercised great care and caution and no humans get injured in trying to do this.

Step 1: Bill of Materials

As promised in the title the key are ingredients are common red clay bricks and a household blow dryer.

You'll need:

23 ordinary red clay bricks. I had some used brick laying around but new brick from Home Depot costs about 17 cents each. You can get firebrick if you want (I didn't). The concrete bricks would probably be okay but I can't speak to that.

An ordinary blow dryer. You can pick up a cheap one at Walmart or Target for around $15 or you can use on that you have. It will not be damaged or changed in this process.

A coat hanger

A BBQ grill at 18 inches in diameter. When all was said and done I used the top grill from my Weber, you will learn more about this decision in the next step.

Charcoal or biochar briquets, the charcoal must be sufficiently formed to rest on the fire grill.

A 30oz steel can. I happened to use Rosarita Refried Beans, this is a standard super market can size and almost any 30oz can should do. A small size may be used but for this design the 30oz is appromiximately the largest size that can be accomodated.

A catalog or magazine, preferably with slick, glossy pages ( clay paper ). We actually only need one page from it which will be damaged in the process.

A long handled tea spoon or small ladle for removing slag.

Masking tape

A 1 foot or so piece of steel pipe of approximately the same diamater as the blower tube on the blow dryer is convenient. Different diameter pipe may be used but if so a smaller diameter should be chosen.

A 2 foot or so wooden stick or pole that can be used in handling the crucible.

A can opener. I didn't show all the tools needed but I'm showing off the fancy, shmancy one I have...

Okay now if we've got all the bits together let's make a furnace...

Step 2: Laying the Groundwork

Here you see the foundation of the forge. The forge should be placed on open ground away from burnable material. It doesn't radiate substantially heat but could easily catch the grass on fire, that sort of thing. The best thing would probably be a bed of sand if you have some.

The bricks are layed out to create an air chamber the size of, well, one brick. The pipe fits loosely between its guide bricks and will be removed temporarily in a later step.

This assembly serves to isolate the forced air feed (blow dryer) from the heat of the fire. Since heat goes up the air feed and blow dryer are placed below the burn chamber. This, in combination with the forced air assembly insulation seems to protect the device adequately.

Note how the pipe just projects into the chamber. I experimented with various things and it seemed like this assembly got the most even air flow through the firebox.

This layer will also hold the fire grill. The firebox sits above the air chamber and the grill used to hold the charcoal in pace. My grill had a supporting wire rod running down the center so you can see how I used the recess created by the pipe and the gap between the two bricks in the back to so that it lays flat and doesn't get bent by the weight of the bricks above. I used a grill big enough so that the outer wire supporting rod didn't impact the forge. Everything used in the forge should return more or less to its original purpose.

Step 3: Assemble the Firebox and Chimney

By placing the grill so that it sits level there is a solid foundation that will hold the balance of the stack. The bricks are placed in the traditional alternating layers ( see intro picture for details )  As you can see from the intro picture I used 3 rows on top of the grill when seemed sufficient for my porpoises.

The chamber will hold the burning charcoal and crucible which we will make in the next step. The size of the melt chamber can be varied and performance will vary in a large part based on the air capacity of the input feed device (blow dryer or other device).

Now that we've got the furnace in place let's quickly put together the crucible which will hold our feedstock.

Step 4: Arthur Miller Where Are You?

There's never a crucible when you need one. Take the 30 oz can of whatever, open the top and remove the contents. Take off the labels, wash the can thoroughly and allow it to dry.  I suppose that part might seem obvious but one never knows....

Now I happen to have...okay, my wife has, this really cool can opener that removes the lid and the top seam so that the can has a tidy and much safer edge. If you do not have such a wondrous device then take a file and file down the inside edge of the can to obtain a smooth lip.

Take the coat hanger and clip off the long straight section across the bottom. Now take your drill and drill two 1/4 inch holes across the diameter of the can. This need not be exact but should be pretty close.

Push the piece of coat hanger through the two holes. Take the remaining coat hanger piece and bend the two shoulder bars down so that it forms a long hook. When we are forging aluminum this hook is used to remove the crucible from the fire by placing it under the wire rod and lifting the crucible from the furnace. It also forms a pivot point so that the aluminum can be poured into the mold.

Okay, now that we've established our place in literary history let's put together the forced air blower

Step 5: The Blow Dryer Assembly

The most important thing, other than don't injure anyone or burn your house down, is don't damage the blow dryer you scrounged. So we attach the blow dryer to the air feed by means of a paper strip and some masking tape. This isolates the blow dryer a large portion of the heat transfer and when you're done the tape can be removed and the blow dryer returned to its usual purpose no harm, no foul.

Remove the pipe from the furnace. Arrange the blow dryer and the pipe so that they sit level. In my case blow dryer had protusions on both sides and I had to put a cloth under the pipe so it would sit level.

Take a page from the catalog or magazine and fold it into halves or thirds until it forms a strip a couple of inches wide. This will be used to connect the pipe to the blow dryer without a physical connection. That will reduce opportunities for heat transfer. Additionally the paper serves as an early warning indicator if heat is presenct, then the blow dryer can be turned off and the assembly removed from the heat to safety.

Tape one strip securely between the two tubes (blow dryer and pipe, see picture). Wrap the strip tightly around the joint several times then tape it securely at the ends. The paper tube now forms a surprisingly strong joint between the two devices to create a single apparatus.

Okay, now we're ready to put it all together and melt something....

Step 6: Assembling and Charging

Take the forced air assembly back to the forge and insert the tube to approximately the same location as it was during initial assembly.

Place the blow dryer so that its air intake is away from dust and dirt. A small towel or piece of cloth can safely be laid under the blow dryer to provide an even safer environment. The towel will get dirty so there's no free lunch.

Place a few rows of charcoal on the fire grill until you fill up the gap created by the first row of bricks.

At this point if you hang the crucible in the fire box chamber it should fit nicely with the bottom of the crucible just above the charcoal. The crucible should hang freely in the furnace chamber and not rest on the charcoal itself.

Preparation of the feedstock depends on what you're using. I used soda cans so I cut the tops and bottoms off using a pair of scissors (not the good ones!) and then smashed the remaing tube flat and folded it a bit. This allowed me to feed in the body seperately from the tops and bottoms.

There is much advice on this, however what I found is this. Cut up a bunch of small pieces and place them in the crucible. When things heat up this melt they will form a pool of molten metal. This will take much larger pieces conveniently. There are limits to this but you can think of preparing feedstock in much the same way as preparing a campfire. First comes the tinder, then the small logs, then bigger logs.

Okay, now we've got a furnace, we've got a loaded crucible lets smelt some aluminum...

Step 7: Smelting and Casting Aluminum

Okay lets get started with the smelt. Leave the blower turned off until the coals are established and have some grey ash on the surface. Turning the blower on prematurely will blow the fire out however once grey ash appears on several bricks the blower will greatly enhance the process from then on.

If you use on those charcoal starter devices with newspaper or whatever get your coals started. Otherwise remove the crucible and spray on a good dose of starter fluid. No need to go crazy, it won't help. Use the same sort of amount you would use the start the charcoal in your grill.

Light the charcoal and, holding the crucible the extended rod ends, place the crucible back into the furnace. **CAREFULLY** drop in additional briquets up to about the level of the crucible rod. Don't over pack, you can always drop in more briquets later.

Take the last two bricks and place them **CAREFLLY** on top of the furnace to form a chimney. They should be placed so that the center of the furnace forms a square framing the crucible. (see picture)

As things heat up the feedstock will begin to soften and then melt. As the metal melts addtional feedstock can be **CAREFULLY** added to the crucible. Eventually you will have either fed in all your feedstock or the level in the crucible will be "full". I wouldn't overfill the crucible, if it gets half full go with that until you a clear idea of how exactly things will go.

Dross and slag will float to the surface of the molten metal. I removed this using a long handled tea spoon. ( see picture ).

Once you have a nice crucible of silvery molten metal ( more or less ) remove the two chimney bricks from the top of the furnace. Hook the crucible rod with the coat hanger hook and lift the crucible out of the furnace. Tilt the crucible to pour the aluminum using the wood piece to lift the bottom (see picture), this approach provides pretty good control on the pour.

In this case I used a muffin tin as the mold. It was handy, worked and readily discharged the aluminum ingots in an interesting muffin shape ( sort of ). As you can see from the picture I've done two melts with this and didn't actually get a full muffin because I ran out of feedstock.

Comments

author
afartinthewind made it!(author)2010-12-12

I have a old cast iron stove i use to melt Al. I cut a old Co2 tank for a pantball gun in half and use that as a crucible, its high carbon steel with 1/16" walls and when I pre heat it to a deep red (and dont overheat the Al) I dont get any sticking and minimal slag. i just welded 3 legs@2" on the bottom and a "U" shaped handle for pouring on the top. gave it a football shape in a vice and good to go. it can hold about 3 cups no problem and can hit a good yellow hot without damage. By far the easiest to make and most durable crucible i have ever used.

author
Snidely70448 made it!(author)2014-03-27

Some paintball CO2 tanks are actually made of aluminum. This could be a problem. I've seen other crucibles made out of empty propane tanks used for camping.

author
egbertfitzwilly made it!(author)2011-04-09

I have featured your comment. You should consider doing an instructable as I believe there is a widespread need for crucibles amongst amateur metallurgists.

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The+SYNer made it!(author)2016-02-19

Will no one mention that what we commonly call aluminium is pure aluminium metal. Aluminium oxide is the major component of the dross you take the top of the melt.

author
Snidely70448 made it!(author)2014-03-27

If you can't think of anything else to do with the molten aluminum, pouring it into a fire ant colony produces interesting results.

http://www.anthillart.com/

author
KeiferMax made it!(author)2013-08-30

I have been looking for an easy way to smelt aluminum and I do believe I will give this ingenious way a try. May I ask a few questions?

Why doesn't the steel can crucible melt? Scratching my head on that one.

The "muffin pan" seems to be steel too... Don't need cast iron? That would be great!

Finally, I think I am going to cut the top off an empty mini propane can used for camping as a crucible. (Of course ensuring it is absolutely empty) do you think the sidewalls of this new crucible will be to thick to use in this application?

Thank you for any response and showing me how simple can be best sometimes.
KeiferMax

author
fish_dude made it!(author)2013-09-28

The steel can has a much higher melting point at about 2500 degrees F
while aluminum melts at about 1,221 degrees F
so you need a much hotter fire to melt the steel

author
fish_dude made it!(author)2013-09-28

The steel can has a much higher melting point at about 2500 degrees F
while aluminum melts at about 1,221 degrees F
so you need a much hotter fire to melt the steel

author
RingoWild made it!(author)2013-03-10

This is completely brilliant. And your Arthur Miller comment wasn't lost on me. No sir. OK, i have a couple of questions.
1) How long does the molten aluminum stay pourable? I'm sure it hardens pretty quickly, but how quickly?
2) Will silicone molds work, do you think? I'm not sure how high the temp goes in your smelting process. My most interesting molds are those made of silicone, so it would be great if they could be used. However, I have a feeling the temp will be too high.
3) OK, it's more than a couple of questions. Does the aluminum retain its flexibility? Could you pour it into a wire-shaped mold and make aluminum wire?

Thanks for your time!
-- Lori

author
retrotimelord made it!(author)2013-01-05

\i live in new zealand and i cant watch the video
why?

author
egbertfitzwilly made it!(author)2013-01-05

It is possible that the content is blocked due to copyright issues over the soundtrack. I have a notice from youtube that says this content has been blocked but it doesn't say where.

author
cfreitas made it!(author)2012-05-14

Very nice instructable, I will give a try on this one. I have only one doubt : I understand that the molds are sand made to permit the gas from the molten metal escape from it when solidifying, but, is possible to make molds from cement or something that I can use several times ?

Thankyou for sharing this instructable.

author
egbertfitzwilly made it!(author)2012-08-04

I don't actually do forging so I can't provide any additional insight appropriate mold materials.

author
xraver7086 made it!(author)2011-04-01

I tried this and i couldnt get the aluminum to melt. any suggestions?

author
egbertfitzwilly made it!(author)2011-04-07

I'd have to know more about your setup. I suspect either not enough charcoal or not enough air. Also what were you trying to melt, I cut up aluminum cans and didn't have much difficulty. A solid chunk might be more problematic.

What did you use for a crucible? Some have had difficulties with heavy metal crucibles, they absorb a lot of heat and can take a long time to get to melting temperature.

You could try banking earth around the sides, this will increase the internal temperature.

author
xraver7086 made it!(author)2011-04-08

i used a tin can, like yyou said. i used a whole bag of charcoal, i was trying to melt soda cans. i used a leaf blower for air and it got extremely hot

author
egbertfitzwilly made it!(author)2011-04-09

I wonder if the leaf blower might be blowing too much air for this configuration? If there is too much air it might serve as a vent rather than a conduit. You might try a smaller fan if you have one. I was actually actually thinking of going the other way and seeing what results I could get with a small cooling fan.

author
DrDontDoDis made it!(author)2011-05-04

I use a leaf blower, but the nozzle must be kept a few feet from the mouth of the furnace or the air/charcoal mix will be too lean and the fire may actually be colder (not to mention you could go through 50 lbs. of charcoal in 15 minutes). If you have a very large melter than you could hook the blower right up. However, if you do go with a leafblower DO NOT use wood charcoal. A leafblower used in a tall, thin furnace could give hardwood charcoal enough air to reach steel melting temperatures (as in a cupola), and ordinary bricks can't handle anywhere near those temperatures.

author
xraver7086 made it!(author)2011-12-05

hey its been a while but ive been thinking of a new plan that uses these materials and a few modifications to increase insulation.

author
egbertfitzwilly made it!(author)2011-12-05

Cool, I look forward to your instructable. I've been toying with a modified design that uses a gas burner, solves the refueling and fire control issue.

author
xraver7086 made it!(author)2011-12-18

unfortunately, my dad used my bricks for a different project with out asking, and they cant be retrieved(under at least 1 and a half foot of cement). With it being christmas, i cant afford the bricks. when i get them, i will test it out immediately.
NOTE: my bday is commin up, and so i expect to get cash to get bricks, so the inst. is coming soon.

author
xraver7086 made it!(author)2012-03-08

I finaly did it!!! Instead of bricks, i just dug a hole and attatched a pipe to the bottom. worked great!!

author
egbertfitzwilly made it!(author)2011-04-18

Do you try again with a smaller fan?

author
xraver7086 made it!(author)2011-04-18

Our county currently has a fire ban and im currently in High School so trying to find the time to do this and a secluded place is really hard, but i plan to use a smaller fan. just need a good, cheap fan.

author
thecrow117 made it!(author)2012-01-08

does this furnice get the aluminum hot enough to make lost foam castings?

author
egbertfitzwilly made it!(author)2012-01-08

Since I'm not sure what the specific requirements of lost foam casting is I can't speak authoritatively to that. The aluminum melts, is pourable and so on ( depending on the crucible to some degree ). The charcoal is consumed so if the process is extended one may need to replenish the coals.

author
jadronx made it!(author)2011-12-21

awesome instructable i will be trying this soon!

author
pdidit made it!(author)2011-12-19

lot of great info here. Gotta try this build some other places you all might like are www.backyardmetalcasting.com and www.metalcastingzone.com

2 things that will help the casting are cover flux and degasser A quick search will turn up sources

author
wilkinde made it!(author)2011-12-18

In your introduction you claim that all aluminum scrap is really aluminum oxide. This is false. All aluminum scrap contains aluminum oxide - which is a clear ceramic with a melting point of 2000 degrees Celsius (3600 degrees Fahrenheit). The base aluminum melts at 660 degrees Celsius. This is why aluminum must be welded with an inert cover gas. Once the thin ceramic surface is fractured in air it oxidizes generating more aluminum oxide, until the over all heat builds up enough to fracture the oxide coating away from the edge - creating destructive puddling of the metal near the weld point.

In terms of your casting endeavor, the only significant issue is that the aluminum oxide coating guarantees there will be slag - no matter how pure your aluminum is.

author
cardboardwizard made it!(author)2011-09-12

I love this instructable. But the part where you said aluminum is aluminum oxide is only partly true. Pure aluminum metal gets an extremely thin layer of aluminum oxide. Also called alumina it is in itself a great refractory & is extremely hard.

author
Computothought made it!(author)2010-09-19

Cool. Have to try this with my heat gun.

author
egbertfitzwilly made it!(author)2010-09-22

You mean as the blower or the heat source? I don't think a heat gun will generate sufficient temperature to be useful but would probably make a dandy blower.

author
sparmar1 made it!(author)2011-05-14

a blowr can give much efficient.

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Computothought made it!(author)2010-09-22

Your probably right though the extra heat could not hurt. I can always go to Goodwill and get a cheap hair gun and not wear out the heat gun..

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moonchylde made it!(author)2010-09-22

Cold air is denser and thus has more usable oxygen. Hot air is just a waist of electricity.

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tomtortoise made it!(author)2010-10-06

Yo im wondering if the can is going to melt holding the aluminum

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asteidl made it!(author)2011-04-18

The can is (usually) made from steel, which has a much higher melting point than aluminum. Different steel alloys have different melting points, so I couldn't say what a "tin" can's mp would be without knowing the alloy, but it's generally around 1370 °C. Elemental aluminum melts at 660.37 °C, while Al2O3 has a melting point around 2,000 °C.

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egbertfitzwilly made it!(author)2011-04-19

Thanks for the amazing useful factoids.

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egbertfitzwilly made it!(author)2010-10-12

It hasn't yet.

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asteidl made it!(author)2011-04-18

Love the idea, will try this soon! I drink a boatload of [citrus soda] and [cola] (I'll be fair, and not advertise, lol), and always save my cans for profitable scrap. I'll see how the scrap yard responds to processed ingots! I'm thinking I might even get a better price, since many impurities are removed, and pretty much did what the large recyclers do. The smaller recycling yards compact the cans, then ship them to a processor that either ships the cans to manufacturer (who processes the cans themselves) or shred and melt them down to ingots. I'll report my findings! :D

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egbertfitzwilly made it!(author)2011-04-18

Please do, I agree that you should be able to get higher prices for ingots although you may have to hunt for it. If you have ready access to a source of biochar/charcoal you might be able to move up the food chain ( buy cans and sell ingots )....

author
Kaiven made it!(author)2011-03-04

The use of the grill cover is brilliant. I think this is going to be the design for the forge I am building. I don't have the resources for concrete, bricks will do fine.

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egbertfitzwilly made it!(author)2011-03-05

Thank you for your kind words. I look forward to hearing more about your project.

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Kaiven made it!(author)2011-03-05

I tested the design today and was able to heat treat two knives! It's great, thanks for the post :D I also manage to melt aluminum in it, so I plan to do a lot more in the future.

author
Appollo64 made it!(author)2011-01-29

This looks really great! But does anybody have any idea on how to make a good mold for casting the liquid metal?

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egbertfitzwilly made it!(author)2011-02-11

There are several instructables for making sand cast molds. Basically a box filled with a combination of fine sand and clay which is packed tightly around a form.

Arguably the cheapest and easiest cast.

author
masoon made it!(author)2010-10-30

what setting did you have your hair dryer set to? Did you let the charcoal burn awhile before using the blow dryer. If I use unheated air will that work?

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egbertfitzwilly made it!(author)2010-10-31

Yes, any forced air source ( such as the blower output from an old fashioned rug vacuum ) will work. I used the cool setting on the hair dryer, its add no value as a heat source.

The more air that gets forced in the higher the temperature. Its not clear how hot this particular can safely get before the bricks begin to crack or the steel can crucible begins to soften and defrom.

I light the charcoal as one would a BBQ grill, when the flames had died down and grey ash begins to appear turn on the blower.

author
Firestorm_101 made it!(author)2010-09-29

I have just had a brilliant idea! I hope its brilliant anyways... I got to a technical career school for computer, and in another class on the other side of campus is a machine tool shop with several lathes and the like. I know they get there Al peices from a factory that tosses the pieces out as scrap, being they must be a uniform size in there machines. I doubt they will give it up to me, but the machine tool shop in the school is going at is constantly, could the Al shavings from the lathes be used for this setup?

author
egbertfitzwilly made it!(author)2010-10-01

Actually I'd suggest you take the class, the ability to do basic machining such as milling and lathing will serve you well all of your life. Casting is just the first step, virtually anything useful will require additional machining. Plus you'll have access to a larger body of folks who can help making useful things. Trust me, they will want to get sand casting done as much as you want to do it!

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