That's a lump of yellow brass, with a bit of copper wire dissolved in it. Things had to be beyond yellow hot to make it melt, and I had difficulty maintaining the heat around the little steel crucible - the charcoal needed nearly continuous tamping. I've figured out that dry bits of 20x20x80mm dry wood seem to be about right to maintain a stream of nice charcoal at the bottom of the furnace. The sweet spot isn't very big, so a crucible half the height of my current one is realistic.
I'll have to work on channelling the air to a more precise point, and getting the fuel funnelling into a smaller hot zone. I'm going to need a lot of fuel when I try melting iron, just for weight to ensure the air blast doesn't blow it all out the chimney!
Experiments have revealed the amazing coincidence that a beer can is about the right size for the furnace core of a mini-cupola that I might be able to power with a cheap leaf-blower. Well, I've managed to melt the end of the hot air stripper anyway...
Thursday, September 2, 2010
I couldn't find an electronic door latch for my workshop door, so I made one. I just used a secure car central locking kit with 2 remotes and a slave solenoid. I Made the contacts from biro springs and empty .22 cartridge cases. Shouldn't have trouble making it work off 12V battery backup either, but for the moment SWMBO just wants it mains-powered.