nifty idea for a tabletop electric arc furnace.

[edsikes]

hey guys was perusing youtube today and ran across an awesome video!

i am looking at trying this myself with a couple graphite crucibles and see if i can use this for melting silver and how it works... just looks like an awesome toy to have around !


https://www.youtube.com/watch?v=VTzKIs19eZE

 

[Shark]

Several years ago I rebuilt starter and alternators. Some of the old Ford starters and heavy equipment had brushes that were spot welded in by the leads. We would cut the lead at the metal contact point and use a 12 volt battery, jumper cables and carbon rods to solder new brushes in place. We still used that method quite often, even after buying a spot welder, it was quick and convenient. That battery would put out enough power to heat the copper contact hot enough to burn skin off in about 2 seconds with less than a full charge. You would definitely need a way to control the input with the setup (welder, by his term) I have an old 110 stick welder I have thought about trying when I get a bit better health wise.

 

[edsikes]

well this looks fairly straight forward.... and doesnt look like it would take a lot of resources to make...

 

[Anonymous]

I think that's amazing- I also got lost in the sugar rockets!

 

[Shark]

well this looks fairly straight forward.... and doesnt look like it would take a lot of resources to make...

That is what caught my eye about the video, too. Seems very simple and straight forward. If you try it, let us know it works out, and any unseen problems that you run into.

 

[edsikes]

well this looks fairly straight forward.... and doesnt look like it would take a lot of resources to make...

That is what caught my eye about the video, too. Seems very simple and straight forward. If you try it, let us know it works out, and any unseen problems that you run into.

definitely will, still watching this guys videos.... lol

 

[patnor1011]

This may be neat idea how to melt aluminium cans and bits in more homogeneous mass. Perhaps even using this kind of device to melt silver from cut mylars. That intense heat may be enough and fast to liquefy mylar fast without much of smoking.

 

[goldsilverpro]

hey guys was perusing youtube today and ran across an awesome video!

i am looking at trying this myself with a couple graphite crucibles and see if i can use this for melting silver and how it works... just looks like an awesome toy to have around !


https://www.youtube.com/watch?v=VTzKIs19eZE

Pretty neat.

 

[Lou]

GSP,

My friend Chris who you know that works with me made a pretty cool version out of a couple microwave oven transformers he re-wound.

He also made a pretty serious spot welder with those microwave oven transformers

I'm mortally afraid of wiring a darn thing electrical.

Thing you gotta be careful with these arc melters is that the heat is so intense you may boil some of the silver (or other metal) accidentally.

 

[Shark]

This is along the lines I was thinking of. This guy had other videos as well with brass, lead and titanium being attempted with little or no success. He does seem to be into a working method.

https://www.youtube.com/watch?v=L3t-jBATM0w

 

[edsikes]

how much are you looking to melt at a time

 

[rolynd]

Well, I admit its fairly easy to make such a furnace. But the problem with arc furnaces is that the temperature of the arc is so high that its easy to accidentally evaporize som of the substance you are melting - including the material the furnace is made from so the melt could be contaminated plus you have some loss due to evaporizing some of your precious metals. Additionally ,because this is carried out in normal atmosphere there is also a loss from excessive oxidizing to be considered. No wonder his copper castings look like a spongy drossy mess. Copper is hard to cast because it easily picks up oxygen (and some Hydrogen as well) when molten. Its usually melted under reduching conditions and is deoxidized with some PhosCopper shot before casting. Sound castings of pure copper without flaws are not as easy to make as you think... His melts are WAY overheated and are not very usefull if you want to use this method for casting something. If you just want to see if it melts and have some fun - go for it.

The temperature of the arc can exceed 3000C°. Pure alumina has a MP of app. 2000C° the alumina bricks are mixed with other stuff which lowers the MP and are usually rated about ~1600 C°max - which accounts for some of the "LAVA" he discovered in his crucibles...

The Frenchman Henri Moissan was the first to experiment with electric arc funaces and after some experiments and trials he made his from calcined Magnesia (MgO) which has a MP of at least 2800C° His original papers can be found here: https://archive.org/details/electricfurnace00moisrich

So while an arc furnace can be fun because you can melt about anything i wont consider it a useful tool from a practical point of view. The metals we deal with have a much lower MP and a electric resistance furnace or a gas fired furnace is much more useful here. An arc furnace is simply overkill to melt some small amounts of silver or gold. A gas fired furnace has the additional advantage that you can fairly easily adjust the melting atmosphere from oxidizing over neutral to reducing conditions so the melt will not pick up much in terms of gasses like oxygen or hydrogen which is a plus if you want to cast something from your molten stuff .

 

[Lou]

Need a bell jar and water cooled copper hearth. First rough down to 10mtorr then back fill with Ar, repeat a couple times and use reduced pressure Ar for melt. Best to press pellets of the powder to prevent arc blowing it all over.

Lou