Pouring was the highlight of any visitor fortunate enough to be there at the right time view it.
The aluminium had been melted, usually to between 400 to 450 degrees, and would have a nice red rosy silver appearance . A steel crucible or pot, suitably lined with special fire clay, and with a pouring vee on one side of the edge, was put upside down on the top exhaust of the furnace. The flames and heat made it very hot indeed! This was called 'warming the pot'.
A frame was slipped over the pot, fitting firmly under the lip of the pot, or crucible, enabling two men to manipulate the pot. It was lifted off when hot enough and placed right under the pouring lip of the furnace. The furnace was then slowly tipped by turning the winding mechanism allowing the molten metal to stream accurately into the pot.
When filled, some powder was shaken on to the top surface of the molten metal in the pot to minimise heat loss and also to coagulate any dust or dross present. While this was being done the furnace was wound back to an upright position.
Two men. one each side of the pot, lifted it by the two steel arms provided, one of which had a double handle a little like bicycle handlebars. Once they were positioned over a moulding box, the aluminium could be poured accurately into the hole left in the mould for that purpose. Then the next mould was similarly filled, and so on.
If the sand in a particular box was too dry, it would possibly collapse, either in patches, or entirely.
Too much moisture in the sand would cause movement by 'steaming' and subsequent collapse.
'Short run' castings could be caused by the collapse of the sand into the mould, blocking off the flow of aluminium, or even if the aluminium was not hot enough, cooling off before it could run the full extent of the cavity.
As the sand became worn with use and started to 'ball', it would become harder to sieve and 'condition'. The resulting surface would have a mottled surface rather than a smooth finish. This would mean rougher surfaced castings which would need a lot more 'fettling', 'linishing' and 'rumbling' before they became something like acceptable.
Once the aluminium had been poured into the moulds, a 'cooling off ' time of 15-20 minutes was given.
Then each box was picked up and sharply knocked on to the floor or a steel frame, to dislodge the sand and the casting in a heap on the floor.
From this still steaming heap, the casting would be removed with a pair of pliers, and left to cool properly, while the sand was also left to cool off.
The sand would later be 'conditioned' ready for the next 'pour'.
Castings would be 'fettled' - if necessary the 'pouring stem' and 'runners' would be removed by bandsaw first. The casting was then hand filed where needed and 'linished' with a mobile sand belt, which assured a good surface and properly trimmed edges where necessary.
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