My first encounter with pot metal was with the purchase of my Mills
Violano when I was twenty years old. The foundry cast the new parts in
bronze. Old parts were sometimes broken or not returned. Since sand
casts are "rammed up" to make a pattern, the molds are of one time use,
and it is a very time consuming process. It generally takes about
forty-five minutes to ram up a pattern. If it does not pour fully, you
have to start over again. If it takes four attempts before you have an
acceptable casting, try explaining that to a customer that wants to pay
$10 for the piece!
After trying several foundries without finding one that would make
needed pieces, I enrolled in a class at the Technical College. What a
great way to enjoy heat when it is freezing outside. After eight
years, I can now cast just about anything. Aluminum melts at about 900
degrees, brass at about 1300, and cast iron at about 3800 degrees. A
good furnace will cost about $10,000, and natural gas is expensive.
These are good reasons why no one wants to do this. However, now that
the cold days of winter are approaching, there is nothing like firing
up the furnace, making some pieces, and heating my place at the same
time.
Detail is also important. Many casters use coarse sand. I can cast a
Buffalo nickel and read the 1918 date on my casting. You know you are
capturing a good amount of detail when that happens. And, why would
anyone want to use pot metal (also called die-cast), when the metal is
unstable? Moisture and sunlight both cause it to distort. Originally
parts were cast using match plates (metal plates that fit together that
have the patterns cast into them). These cost several hundred dollars
to produce and are great when you want to manufacture hundreds of the
same piece, but are unfeasible when you only need a couple of pieces.
Greg Filardo
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