This might be of interest to members that are casting metal or
want to try. Search on "graphite crucibles!"

"Budget" graphite crucibles may be purchased via
http://www.legend-reno.com. A #8 size -- probably the largest you'll
ever need -- runs about $20. I've had no problems with them to date.

Bill in Boulder, "Engineering as an Art Form!"

Last Saturday the 21st I was invited to a meeting for Live Steam fans
down in Colorado Springs. While the thrust was towards the
establishment of a Live Steam Miniature Railroad society there was
considerable interest in foundrywork and casting in general. One
individual showed a pair of locomotive wheels that ran 20 pounds apiece,
imported from Australia! Our host had bought a "Foundry
Kit" for about $200 that had a cast refractory furnace, a welded steel
crucible, a tiny flask about 6"x6", a torn bag of silica sand bonded
with bentonite and a collection of kitchen tools!
While one group tackled assembling and firing the furnace I
lead the effort in producing a mould. We hand mixed ((mulled is an
overstatement) the sand with water and got it to a slightly wet state.
At this point I would have covered it up for a week but we pressed on
with the moulding. There was a large button/plaque in the kit of parts
drilled for rapping and pulling which went onto the follow board and had
sand sifted (kitchen strainer!) onto it and tucked in. The flask was
filled, rammed, and struck off, then rolled over and the cope was done
next. When it was ready there was considerable amazment that nothing
fell out. Well I had rammed it too hard just for this reason!
At this point they had a few pounds of ZA-12 (Zamac) ready to go
so I first made them pour one muffin tin for practice and then the mould
in a steady stream. It steamed but did not bubble so I was hopeful.When
shaken out it had run correctly but suffered a slight hot tear due to
too
hard/strong of a mould. But the audience looked as if they had seen a
rabbit pulled from a hat!
Plans were instantly formulated to run off some 2 1/2" wheels
for railcars and one individual announced his plans to build a 24"
cupelo but I pointed out that it would put out ~3-5 tons an hour and
that a 6" one would 200-250 pounds an hour that would keep him quite
busy! So we came home! You would have enjoyed it! The meetings are held
on the third Saturday of each month and I will try to keep them on the
foundry track! Drop in!

Bill in Boulder, "Engineering as an Art Form!"