For years I have wanted to be able to cast metal (aluminium, copper, brass, bronze and silver) at home. This all stems from my child-hood days when my brothers and I used to melt aluminium and lead on an open fire and cast the melt into Plaster of Paris moulds.
During my time at high school I made the pattern and core to cast a block for a small steam engine, but did not manage to cast it before the end of the academic year. In more recent times I have cast recovered silver into ingots, again using an open fire heat source. Today I have numerous projects that might benefit from casting capabilities including tools, retort clamps and bosses, instrument cases, and maybe even a resurrection of my old steam engine in cast iron.
Figure 1. Charge Melting in Home-Made Gas Furnace
The results of many of these early casting experiments were barely satisfactory. Getting enough metal for the job to temperature was challenging, and the lack of fluxes and de-gasing agents combined with uncontrolled combustion in an open fire often resulted in problems.
Fundamentally, sand casting is a remarkably straight forward process that has remained largely unchanged for hundreds of years. A good primer on the topic is ‘The Complete Handbook of Sand Casting’, C. W. Adam, TAB Books, 1979.
I don’t profess to be an expert on casting and I am not trying to write a book on the subject. The following pages describe what I have have done to get making real castings, why I did things in a particular way, what worked and what didn’t.
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Maybe this will inspire you to give casting a go too?
Update: My original casting experiments were with aluminium but I have extended my repertoire to brass with a somewhat higher melting temperature (900 to 940°C). My set up will melt 1.5 kg of brass to pouring temperature in less than 30 minutes. My castings are still not perfect but I learn more with each effort.