Build a foundry and sand-cast aluminum.

Step 7 Assembling the furnace

There is a simple way to do this-

1. Insert hair-dryer into air chamber
2. Put fire chamber on top of air chamber

-Which is easy as pie but extremely dangerous. If the fire chamber is nudged even the slightest bit the whole thing will topple over, creating a gauntlet of hot coals and molten metal at your feet.

On the other hand though, being able to remove the fire chamber from the furnace gives you the advantage of being able to shake out the coal dust that will eventually clog the holes to the air chamber. This allows you to keep the fire burning hot longer for multiple melts.

If you feel you can't handle having the fire chamber loose, than you should dig a fire pit, fill it with sand, and put metal stakes in the ground running along the sides of the cans. This will hold the cans in place but still allow you to quickly remove the fire chamber.

Comments

[Deadskull57]

Cool, I've been looking for a good foundry instructable, looks like I'll be taking a trip to the goodwill for a cheap hairdryers.

[sniperHunted]

can you hook up a miniature A/C in replacement for the hair dryer.

[unseen wombat]

On the almost-identical furnace I built years ago, I screwed three small steel tabs to the outside of the wall of the plenum such that they stuck up above the top. Then the upper can just slid right down inside them. No chance to topple and perfect alignment every time.

The tabs were about 1/2" wide by 2" long and 1/16" thick and available at home depot or lowes. I attached them with two screws each so they couldn't pivot.

Also, doesn't your hair dryer melt? I had an old dryer from the 60's with a hose attachment which I hooked up to the plenum with some pvc fittings. The PVC melted the first firing. Then I got some brass fittings and it was fine.

[Fenris The bbw]

I do something similar to the steel tabs with stakes driven into the ground along the edge of the cans. Not as pretty, but it holds them in place.

And I've been wondering about the dryer myself. It's got scorch marks all over the nozzle, but it seems to not be melting at all. 

[canis]

a simple solution to the "topple" effect would be a steel plate (wider in diameter than the coffee cans) with holes drilled in it.

[ryno85]

Could some kind of large hose clamp be used to keep the top can from falling off?

[extrordinary1]

you can if you cut the bottom out of two cans, and the top of course, and cut them up the side and wrap them around the top and bottom equally, then clamp together.

[Fenris The bbw]

Don't know. I've never seen a hose clamp big enough to try.

[pfred2]

They make pretty big hose clamps, that and you can chain smaller hose clamps together too!

[maz22]

or you could use a metal bar clamp

[Fenris The bbw]

I like being able to take the top off. If lighter fluid or, god forbid, molten metal, starts to leak into the bottom chamber, it's good to be able to put the fire out. If I couldn't take the top off, I'd have lost that hairdryer several times over now.

[pfred2]

I'm surprised the hair dryer works well enough to develop a blast. I have a little squirrel cage fan I use on my furnace connected to a stainless steel piece of tubing. The top comes off of my furnace too. Once I get my fire burning I pretty much plan on letting it go until the fuel burns out in it.

[Fenris The bbw]

I was too. Nice furnace by the way. Are those lawn mower wheels? I may have to incorporate some wheels into my next design and i've got a dead lawn mower, so I've been thinking about doing that.

[pfred2]

The bottom of my furnace is an upside down lawnmower. I hear the ones with all the same wheels you can just flip over. Mine took a little more work to level out.