The cope half of the flask is now in position
and the surface of the sand and pattern have been lightly dusted with
Now back to some of the steps I skipped showing
earlier. Using a kitchen flour sifter I sprinkle sand on to the pattern.
It is important to have very fine sand on the pattern so that the finished casting will be as smooth as possible.
After covering the pattern with sand from the
kitchen sieve, I move on to a bit coarser screen. Finally I just scoop
sand directly into the cope to fill it.
As the cope fills, the sand must be rammed
firmly into place. Be sure to do the edges and corners to keep sand from
falling out when the cope is lifted from the mold later.
Use a flat bar to scrap the surface smooth. The
sink plumbing is a sprue cutter used to make a hole into mold where
the metal will be poured.
This tool is used to cut a funnel mouth on the top of the sprue. Use your finger to smooth away loose sand.
Rap the edge of the flask with a rubber mallet to loosen the pattern from the sand inside.
Here the cope has been lifted off and set aside.
There is a little sand stuck to pattern. I use compressed air to blow
it away. The casting will have metal flashing where this sand appears but will be relatively easy to grind away. The
small circle of sand is left over from the cutting and cleaning the sprue.
I use a melon baller to cut a cup at the bottom of the sprue.
Remember the ridges of sand I made earlier? We can now cut that away to form a trough in the drag to carry metal.
This is another mold showing all of the ridges
removed (with the flat trowel). I will now cut gates (troughs) along these
lines which will match those in the cope.
A folded piece of sheet metal makes a good gate cutter.
The gates go to the sprue cup.
They are all done now. Be sure to smooth and remove all loose sand.
A swab bottle is used to apply water to the sand where it meets the pattern. This helps to firm the sand next to the pattern.
Rap lightly on the pattern before lifting it
out. Note the magnet on the right side. Since the pattern was cast iron I
the magnet as a handle to help me lift the pattern out of the mold.
This is a closer view of the mold. The lighting makes it appear that there is a metal piece in there...it's just a hollow mold!
Now on to the cope (the top half of the mold).
I use the melon baller again to clean the edge of the bottom of the sprue
hole. Also use your finger to gently smooth and firm the edge here.
Just a bit more cutting and the troughs formed
by those earlier form ridges on the drag are ready to carry metal to
the new casting. Again, the lighting makes it appear that there is an object in the sand...it is just the mold of the piece.
The cope is replaced on the flask and the
surface scribed with the U-shaped wire tool. This process helps to evenly
distribute the mold weights on the surface of the mold.
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