"Harold and Susan Vordos" wrote in message
. net...

"Adam Corolla" wrote in message
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"Harold and Susan Vordos" wrote in message
et...

"Adam Corolla" wrote in message
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"David Harmon" wrote in message
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On Thu, 18 Oct 2007 13:17:43 -0500 in rec.crafts.metalworking, "Adam
Corolla" wrote,
Then you'll have to go with tungsten, or maybe iridium... You can get
pure
tungsten for three dollars an ounce, and it's about 75% heavier than
lead!
But I guess even with lead's price increase, it's still much cheaper
than
tungsten.

Some time ago I found a used carbide diamond-shaped tool insert lying
on
the sidewalk. I don't use insert tooling, so I was surprised to find
how
heavy it was for the small size. Tungsten carbide, presumably. How
much does used carbide go for per pound? Would sinkers or boat keels
molded of used inserts embedded in epoxy be economical?

Well, tungsten carbide is of course much less dense than pure tungsten,
but still denser than lead I believe. I guess it would depend on the
ratio. My guess is that they would not be economical--due to the much
higher price of tungsten scrap vs. lead scrap.

The biggest problem you'd face is fabricating. How would you propose it
be fashioned? Tungsten melts at such a high temperature that it is not
feasible to melt the stuff. It's generally handled via powder
metallurgy. It's clearly beyond the ability of the average home type
individual. Damned expensive, too.

Harold

Yeah... Though an acetylene/oxy torch can get slightly hotter than the
temperature it takes to melt tungsten, what do you melt the tungsten
*in*? A crucible made of any other material would melt before the
tungsten, right? Plus, you'd have to be able to concentrate the heat
*really* well or radiant and convective cooling would prevent the W from
ever getting anywhere near as hot as the torch... Yeah, I can see where
it would be very difficult.


Achieving the temperature isn't the problem. We can do that with an
induction furnace. As you alluded, containing the heat is. Tungsten
melts well above almost everything---something like double the temp
required to melt high temperature refractories.

Harold

I see. Is it ever necessary to actually melt tungsten?