Re: [CAD_CAM_EDM_DRO] [OT] melting aluminium

It is very easy to build an electric furnace, just proberly not an induction
furnace. Lots of the field is 'wasted', if you want, heating up bits of
metal you don't want heating. You'll melt you specs onto your face as well
if your not careful, I imagine that'd be quite painful. He he he, you might
even end up inducing arcs to leap off metal stuff around you. The metal gets
so hot because the field is trying to move through it so quickly. It's
moving back and forth really fast and the metal can not keep up with the
field changing direction so much in so little time (High frequency).
Impedance is the resistance of something to an AC waveform, the metal's
impedance is quite high to such a massive change so it's resistance gets
high. Not amazingly high but with such a powerful field it doesn't matter,
it's going to do something evil to the metal whatever happens. Instantly you
turn the metal into what is basically a heating element with no wires
attached. The metal melts obviously. I wonder if cutting the metal up into
really small pieces would increase resistance significantly enough to
increase efficiency. It'd have to be cheaper to cut up the metal than the
waste heating it. I can't really see a use for them at this level. I think
they're used for very clean melts of important metal in general. So there is
no worry about carbon, sulphur, silicates etc contaminating the metal.

I heard the price of electricity in California has absolutely rocketed!
Sherline tools have actually had to add 2% or something onto the price of
their tools because the cost of the power to make them has risen so much
they will be loosing serious cash not to. Lindsay books publishes a book by
Gingery on building a resistance wire melting furnace called 'Lil' Birtha'
that will melt aluminium. I've seen this furnace built on someones web page
but I can't for the life of me remember who. The guy had also built his own
arc welder from old microwave transformers (These are !LETHAL!) and a mini
lathe for machining foam with a hot wire. He had pictures of melts he'd done
so the 'furnace', or big and very hot oven to me, does work. I'd go with a
cupola, purely because I'd love to see the pictures of you scaring the
neighbours into migration with it.

No thanks, it's against my diet plan,
John H.