[SEL] casting metal at home

[Richard Allen]

The first thing I ever sand cast at home was a radiator cap for a
Caterpillar 22 tractor. The new cap from Caterpillar was priced at more
than I paid for the tractor, so I made my own. That was in 1969 and the
last I saw of the cap some years back it was in good shape. I made the
cap from Zamak zinc-based alloy, which has an undeserved bad reputation
from its superficial resemblance to pot metal. The gears in my 65-year
old Atlas lathe are made from Zamak, which is proof enough for me that
it is pretty good stuff.

I have also sand cast various aluminum alloys with good results, too.
The zinc-based Zamak often has better mould fill-out because of its
greater fluidity and much higher density, but for me it is pretty much
a toss-up between the two types. What I use depends on the application.
If bright shiny appearance is needed and is the ONLY consideration,
then use aluminum because Zamak quickly develops a very characteristic
battleship gray color and items cast from it resemble being made from
pure Portland cement. Zamak electroplates extremely well. Aluminum is
lighter in weight. Zamak is a good bearing alloy for light service.
Aluminum handles high heat better. Neither corrodes easily. Over all I
prefer Zamak when I have a choice because it melts at a lower
temperature than most aluminum alloys, but it costs more unless it can
be salvaged from discarded vacuum cleaners, washing machine
transmissions, etc.

When thinking about making a casting, don't forget about using Zamak.

Work and play safely!


Rich

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