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This
page is a record of the progress I am making setting up and using a
hobby aluminium foundry. Don't copy what I am doing it can be very
dangerous and requires a lot of knowledge and experience to do it
safely. Before considering any of this you must first read my disclaimer page. |
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One
of the most common methods of producing casting moulds is using green
sand. This is where a mould is formed by ramming green sand (a blend of
sand and clay) around a pattern, the pattern is then removed leaving a
hollow recess the shape of the casting. For anything more than the most
basic of castings it becomes necessary to use a two piece mould, with
the sand being formed to the required shape in a cope and drag. It's
always best where possible to use a metal cope and drag which will not
burn, but often in hobby foundries wood is used as it is more readily
available and affordable. In this case extra care must be used to
prevent molten aluminium coming into contact with the wood where it
could cause both fire and dangerous fumes. |
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One
of the requirements of the cope and drag is that they are aligned
accurately together and can only fit one way (the cope shouldn't fit if
it is rotated through 180 degrees). This is achieved by having the
Offset Block in one corner of the Drag and making the Locating Blocks a
snug fit against the corners of the drag and the offset block.
To stop the cope floating off the drag when metal is pored into the
mould the two halves can be clamped together using G-Clamps over the
Clamp Blocks.
The simple design here can be adapted to suit any
size of Cope and Drag and can be made from any suitable available
wooden board. |
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The length and height of each side can be any dimension
to suit casting size you require. Side one however should be longer
than required by four times the thickness of the wood you are using
(dimension X above).
The sand retainer strips are made from thinner material; I have used
3mm hardboard. The sand retainers are pinned to the inside of the cope
and drag to stop the cope and drag lifting off the sand when they are
being turned over.
The sides should be glued and screwed together. If the board you are
using has a facing material that won't accept glue, this should first
be removed from the glue joint areas. All other components can be
secured firmly with screws onto the outside of the cope and drag. |
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