Introduction: Quick and Cheap Aluminum Melting Furnace Setup

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About: Dad and hubby, good food enthusiast, solar energy, boating, making stuff, melting stuff, and raising chickens.
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 submarineboat.com
Home Foundry
BackyardMetalcasting.com ...Melting and casting metal yourself

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

Step 1: 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

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

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

  • 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 submarineboat.com

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