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

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.

[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.

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!

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).