Making Small Brass Castings
Make a model of the desired size and shape from paraffin wax.
Procure a piece of iron pipe about 2 1/2 inches long and of a
sufficient inside diameter to admit the model, with at least 1/8
inch clearance at all points.
Now make a cone of paraffin about 3/8 of an inch high and the base
of a diameter a trifle larger than the inside diameter of the pipe.
Into the vertex of this wax cone force a phonograph needle, blunt
end first, so that there is 1/4 inch of the point projecting from
Then heat the cone around the edges and force it into one end of
the pipe, with the vertex in (Fig. 1). The wax will harden and hold
the cone in place.
From the open end of the pipe insert the wax model and stick it on
the sharp point of the needle (Fig. 1). Procure some Plaster of
Paris or the investment compound used by dentists in making gold
inlays. Mix this with water until the mixture has the consistency
of heavy cream.
Take a small camel-hair brush and paint the model with this. Then
add a little more powder, so that the mix- ture thickens a trifle,
but yet is not so thick that it will not run freely.
Fill the pipe with the paste in this state (Fig. 1), and lay the
whole on a wire screen far enough above the flame of a Bunsen
burner so that the wax will not melt. Leave it for at least one
hour, then lower it to a point about one inch above the flame.
When the wax cone has melted and run out, pull out the phonograph
needle with a pair of pliers, and let the melted wax of the model
run out the hole left by the needle. Re- move from the flame and
Pour the melted brass into the depression left by the cone, and it
will run into the mould thru the needle hole.
Allow it to cool, wash out the Plaster of Paris or investment
compound, and you will have a perfect reproduction in brass of the
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