Q&A for How to Build a Metal Melting Furnace for Casting

Make sure that there are no kinks or leaks in your gas hoses. You also want to be careful with your sources of fire. It doesn't take much—if you drop a flaming hot piece of something on the wrong kind of flooring, it can be a big problem. Don't work in an enclosed space, either; if you're working in a garage, for instance, make sure that the door is open so you don't poison yourself.

Of the metals that you’re likely to use for casting, lead is among the easiest to melt. There are other metals with even lower melting points, such as mercury (which is liquid at room temperature) and gallium (which will melt in your hand).

It’s possible, but you need specialized equipment that isn’t generally available outside of a lab. Under normal conditions, diamonds start to burn at around 1,292° F (700° C).

In a home-made melting furnace, you should be able to melt cast iron, aluminum, lead, silver, gold, and copper. You will likely need a more powerful furnace to melt alloys like steel or bronze.

A clay crucible, which needs to be fired, or a graphite crucible, which can be bought online.

You will need a Type K Thermocouple and a digital temperature meter. I purchased one on Amazon that goes up to 2300 degrees F.

Try induction coils to melt steel. Chromium is more difficult because of oxidation.

No. Tungsten melts at 6192 degrees F -- way above coal or charcoal's burning temperature. It's also above the melting point of any ceramic crucibles.

Coal is extracted from the earth. Charcoal is made from burnt wood.

Salt has a low melting point at 801 C compare to metals, so lab equipment like the tripod, etc. is practical. You can also use test tubes to melt salts under fire. If you don't have any of this, just put the salt in any heat-safe kitchen vessel, then melt it under your gas stove. Be very careful.

Titanium melts at 1,668 °C.

A clay or ceramic mortar can work as a crucible; however, some have impurities or can trap water inside and will crack under the heat. Other materials like glass or stone make poor choices for a crucible. While a clay or ceramic mortar may work, it is not guaranteed.

Yes. Silver melts at 961°C. Charcoal burns at 1260°C.

In short, the temperature of the furnace will be irrelevant, as the fuel will be burning at a constant temperature. (For example, charcoal will burn around 1,260 °C, thus heating up the furnace to around that temperature.)

Pet coke has a high carbon content, so you should get a hot flame from its combustion. You might get some sulphur rich fumes, though, so it might be a bit unpleasant. Zinc melts at about 420 C.

No, even heating neodymium for too long will destroy its magnetic properties. I would presume that melting it would alter its structure so greatly that it would no longer hold the capability to be re-magnetized by an electromagnet.

A muffle could be a stainless steel or ceramic container in which the material to be melted is in a crucible, or heat-treated by tempering. The muffle is usually sealed by the door of the furnace. The purpose of the muffle is to protect the contents from the furnace atmosphere.

Tin melts easily at about 180 C. You could melt it in a steel container, or better still, in a clay or graphite crucible.

Yes, as coal as it has a burning temperature of 3000 - 3500 °F and iron has a melting temperature of 2800°F. They used charcoal to melt iron before coke was invented in the 1700s.

If buried in hot coals, aluminum can melt. It is difficult to melt aluminum cans into a (small) pool of liquid metal, because they are very thin and oxidize readily in hot air. You usually end up with flaky oxide sheets and no liquid metal.

Heat the blade until it's a yellow color. Then quickly dip it in some heated oil to cool it. If you rub a file against it and it slides off the steel, it is hardened. If not, try it again. Caution: Your blade can warp doing this.

As long as you take your time, do a bit of research first, and follow some basic safety rules, yes, it is totally safe. I have built a blacksmith's forge using an almost identical technique, and unlike many of the "easy, do-it-yourself" tutorials, this one is a perfectly functional design. Just remember to only use it outside, or in a well vented area, wear proper clothing, and follow the usual fire safety rules.

That would work - but you'd need air flow. Charcoal can burn upwards of 1100ºC with plenty of oxygen.