After following the
previous three tutorials you should be ready to vent
the mold to get the metal into those hard to reach
places like reins of horses or the bayonets on rifles.
In the case of sprues surrounded
by a frame you just cut a small vent from the problem
area to this sprue. (Fig.1).
Use a sharp modeling knife and a
HEATED mold to get an easier cut.
Make as many such vents as required to allow the metal
into the problem area.
(Fig.2) If the figure is not surrounded
by a frame then always cut FROM the
figure to the TOP of the mold.
NEVER cut a vent to the bottom of the mold as the
molten metal will only pour out through this.
When you have Vented the mold to
your satisfaction you repeat the previous tutorials
to cast the figure with safety as top priority as
always.
(Fig.3) SUCCESS - The bayonet has
filled this time.
However a slight shift has occurred
because the two halves of the mould were at a different
temperature. Try to keep both parts of mould
the same temperature to avoid this shift.
(Fig.4) Now to remove you beautiful
new cast figure from the mould. Carefully BEND
the mold when removing the figure and you
reduce wear and tear on the mold (which makes casting
in future more prone to errors) and damaging the figure
(after all your effort it would be a shame to ruin
it with a moments carelessness).
Tips to remember:
- Use a sharp knife and heat the
mold when cutting vents.
- Cut from the problem area to
top of mold or to surrounding sprue.
- Recast figure with attention
to detail.
- Wait at least five minutes before
opening mold.
- Keep both parts of mold same
temperature.
- Bend the mold when removing figure
or damage may occur.
|