Greensand Casting

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Casting etc 004sm.jpg

This is a picture of my first casting, just out of the sand. It became the hawsepipe cover for my sailboat, to replace the one that was carried overboard when the anchor chain ran out too fast a couple of years ago. The sprue ( that lumpy bit on the end) has not been removed yet.

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This is the MDF pattern for my next project. It is for the end of a telescope, and will carry the primary mirror cell.

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Here is the flask ( cope and drag) that will hold the sand which forms the cavity mould. The parts are keyed together so that the moulded piece will come out in the right orientation. For some patterns there are parts in both the cope and the drag, and they must match.


This is the pattern in the cope, ready to be extracted. 

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The pattern has been removed, and cavities made for the sprue and riser. ( Where the metal is poured in.)
The white powder is talc (Baby powder ) used as a mould release.

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Here is the drag, packed with sand and the patterns (dowels) for sprue and riser still to come out.

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This is the flask assembled, with lead weights on top to keep the drag from floating on the liquid aluminium. The small pellet on top is a foil packet of pool chlorine powder that will be used to degas the molten metal before the pour.

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This is the assembly after the pour, with a big lump of metal in the sprue, and some peeking out of the riser. This latter indicates that the pour filled the mould. The muffin tin holds the surplus that we do not want to leave in the pot to solidify.

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This is the raw casting, showing where in the telescope it fits. Eventually it will be connected to the mirror cell with adjustable bolts.

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This is an assembly with the second casting included. Together they will hold the mirror of the telescope and will provide collimation adjustment.