A Foundry in Every Kitchen

WolfWithoutAClause writes "Bored with making the same old food or plasma in your microwave? David Reid sounds like he is. He's using his domestic microwave oven to melt iron, silver and bronze! Over 900C! I don't know about you, but I'm going to be checking the temperature of my pizza rather more carefully in future..."

Comments

For more cool Microwave science...

[DeafDumbBlind]

Try putting in a CD (Yet another use for those AOL 7.0 discs that they keep sending)

A burned out light-bulb causes some interesting things to happen as well :-)

Make your own jewlery

[dgp]

This is sweet! I could forge my own One True Ring - Deep inside Mount Panasonic, a master ring was made on High-Power to rule them all!

Microwave Pizza??

[RJ11]

I don't know about you, but I'm going to be checking the temperature of my pizza rather more carefully in future...

Who in the world microwaves pizza? It gets very soggy and loses almost any redeeming qualities.

Microwaves are potentially dangerous---no shit.

[dc.wander]

I feel obliged to say something, before some 13 or 14 year-old kills themselves:

microwaves are high voltage, high current devices. they can kill you EVEN IF THE POWER IS OFF AND THE DEVICE IS UNPLUGGED (ex: by discharging of a large capacitor). Unless you really know what you are doing, don't open one up. i've been trained in servicing electronics, and even i wouln't go near one of these things.

see: Notes on the Troubleshooting and Repair of Microwave Ovens for more information.

Re:Microwaves are potentially dangerous---no shit.

[Anonymous Coward]

microwaves are high voltage, high current devices. they can kill you EVEN IF THE POWER IS OFF AND THE DEVICE IS UNPLUGGED (ex: by discharging of a large capacitor). Unless you really know what you are doing, don't open one up. i've been trained in servicing electronics, and even i wouln't go near one of these things.

Good call. If you still feel the urge to work on them, good work habits include wearing good insulated shoes and working with ONE HAND only (other behind your back!), which limits most current paths to just your hand. Usually the worse thing that happens is your hand is tossed off of what you're working, but you're less likely to have a path through your heart, which is when it gets dangerous... Another safety precaution is to discharge the caps with a screwdriver (but be careful, might damage something with a dead short!)

Re:Microwaves are potentially dangerous---no shit.

[Brymouse]

First of all, most large caps is a microwave have 10 meg-ohm resistors on them to bleed off the charge. All you have to do is put a large screw driver across the cap to test if it is safe to handle. If the resistor is in good condition, nothing should happen, if not, you get one hell of a spark. No harm done to you, but maybe the screw driver!

Now as for servicing a microwave, 9 time out of 10 they have a partial diagram in them, that shows the major componits. Once you have this, it is easy to work on one, as long as you know the basics of how a microwave works.

Short version of how a microwave works (for food!). First, power comes into the unit, goes through a set-up transformer, is rectified, and smoothed though the cap(s). Then this high voltage is applied to the magnatron (the thing that makes microwaves), and the resulting radiation is couppled into a waveguide. In this waveguide is a metal disk with holes in it, that "stirs" the microve energy. From here it goes into the chamber, and heats your food. It accomplices because the water in food absorbs the 2.4 GHz radiation.

That's how it works.

It's to protect the plastic floor of oven.

[Blaede]

There's nothing wrong with heating up a metal in a microwave, that in itself will not ruin the unit. What is a big problem is the heated item melting the inside floor of the oven due to (drum roll, please), HEAT! The item gets hot, and melts a big hole in the floor, therefore ruining it. So go ahead and heat metals in your microwave, just don't let it touch the insides directly. That means using a plate, cover, etc.

Clothes Dryer

[Anonymous Coward]

Back in 1981, I built a small clothes dryer from a microwave. I drilled a hole in the front glass, placed a vacumm tube through it, with a vacumm pump on one side, and a vacumm flask in the m-wave. I them tested various fabrics with differing amounts of H20 in them. Amazing that a jean leg dryed in 15 minutes, tee-shirt in 5, a wool sleve in 25 minutes (low heat to avoid shrinkage). Based on energy calculations, it used about 2/3 the power and was running at lower overall temperatues (I suspected that local temps ran over boiling, but then again they do in a dryer).
I wish I had the money back then to persue the idea.

Photos overexposed

[dmiller]

Notice how the crucible and insulating assembly looks over exposed in the photos linked from the article. I wonder if this is because they are emitting a large amount of IR? This would be invisible to the eye, but visible to a CCD camera, even through a the cheap plastic filters they use.

Don't Try This at Home, Kids!

[Greyfox]

That's what the microwave at work is for!

metal clays are easier to work with

[g4dget]

If you want to make small pieces of jewelry or other parts, there are metal clays (search on Google): almost pure precious metal (silver, gold) with a little bit of binder. When you heat them, the binder burns away and the metal sticks together.

Other than that, the technique sounds unnecessarily laborious and complex. There are easier ways to melt metal, even at home. Thermite, for example, should appeal to people who like fireworks. Basic textbooks on inorganic chemistry, mineralogy, and metallurgy can tell you how. (Don't people learn this stuff in high school chemistry anymore?)

Re:Pizza won't hit 900 Celcius

[prockcore]

Maybe the pizza isn't a very efficient absorber of energy, but the cheese certainly is.

As anyone who's ever bitten into fried mozzarella sticks can attest.. cheese is the one magic food that has the potential to turn into molten lava.

Do not try this at home!

[Anonymous Coward]

I've cast aluminum (1200F) and iron (2200F) and am truly concerned about the total lack of safety equipment that this guy presented. When I cast the molten metal, we wore complete body leathers and used tongs to keep the hot metal at least 1-2 feet away. To pick up a container using bare hands and sleeves is nuts. Molten metal will burn through unprotected skin.

A serious problem with pouring molten metals is the risk of moisture in the moulds. For example, if a fly happened to be in the mould when the metal was poured, the metal would explode from the moisture with enough force to hit the ceiling. I sure don't want to be in a room when its raining molten metal!

You uncircumcised heathens!

[Kibo]

I've no quarrel with frozen pizza designed to be microwaved. When hunting and gathering one must accept what one finds. But you savages who defile perfectly excellent cold left over pizza have no place in a civilized society. Some social ills make me wonder what horrible childhood pain would cause a person to behave in such a disturbed manner. But those dysfunctional individuals microwaving delectible left over pizza, clearly they must be shot, incinerated, with their ashes encased in glass rods, buried under a mountain or maybe a salt flat, then covered with lye and never spoken of again.

When people ask "What's this world coming to?" you can be sure that people who microwave perfect precious left over pizza are at fault. Filthy animals!

Microwave to heat � best container material

[Saggi]

Microwaves in a microwave oven are using a frequency that matches the vibration frequency of the O-H bond in water. Now if a microwave should be converted into heat, it must hit a molecule, where it can leave the correct energy. This is quantum mechanics, so only the precise amount of energy can be transferred to the vibration. If the wavelength of the microwave doesn't match, energy will not be transferred.

Now the described experiment used several different containers for the metal. These containers absorb the microwave and convert them into heat. To obtain the best container material, you should look for materials whose vibration energy of some of its atom bonding matches that of the O-H bonding in water.

The O-H bond has been chosen as most food contains water. Materials without water will not heat in a microwave oven. (Unless it contains molecules that match the frequency in other ways).

Weaponry

[DarkHelmet]

Oh yes, it's a foundry.... Yes, now you can make your own weapons for your Warcraft action figures...

Oh, you're all geeks.... the lot of you... Not nerds like the site says, GEEKS!

The worst thing about this is that some of you here will actually think this will Get you chicks!

Argh! I need my pills? Where are my pills?