Casting Metal Parts. Intricate Designs And Fretwork.
Casting Metal Parts
Although metal fittings, such as anchors, bollards, chocks,
and propellers, can be purchased ready for use from ship model making supply houses, many
ship modelers desire to make everything themselves. Of course, such parts can be cut from
soft lead, but it is sometimes easier and better to cast them. To make an anchor, for
example, first prepare a pattern cut from close-grained wood. Build a 1/2 in. high wall of
wood or modeling clay on a square scrap of wood and fill it with a soft mixture of plaster
of Paris and water. Grease or oil the pattern, lay it on the mixture, and press it in
until just one half is submerged as in Fig. 33. Leave it until the plaster dries. Then
remove the pattern and countersink several holes in the margin of plaster. Replace the
pattern, build the walls up another 1/2 in., grease the top surface of the hardened
plaster mold, and fill with newly mixed plaster of Paris. Place a thin piece of wood on
top and leave until dry. Then carefully separate the two sections, remove the pattern, and
cut a gate or spout from the crown or heavier end of the anchor impression to the edge of
the mold. This will serve as an entrance hole for the molten metal. Also, make hair-line
scratches from the ends of the flukes and shank to the mold edges to serve as air
vents.
Finally, dry the mold thoroughly. It must be bone dry before the metal is poured in. If a number of castings are to be made, use half plaster and half powdered asbestos in making the mixture for the mold as it will stand up better under the heat. As a backing top and bottom for the mold it is well to use two pieces of thin wood such as 1/4-in. three-ply not much larger than the mold, allowing the plaster to remain attached to them. To make a casting, lightly clamp the two parts of the plaster mold together. Melt some lead in a ladle or an old saucepan and pour it into the mold through the gate. Until the mold gets thoroughly hot, the first few castings may be pitted and unusable. Incidentally, blocks and deadeyes also can be cast from metal, if desired. A compound mold consisting of several deadeye impressions connected by runners leading to a single pouring gate will speed up the work. When the tiny parts have been cast, they can be smoothed with steel wool and emery and finally enamelled.
Intricate Designs and Fretwork
Intricate fretwork for ship models can be cut
from wood without splitting if an ordinary nonwaterproof three-ply panel is used (Fig.
34). Draw the design, score around it with the point of a sharp knife, and remove the
waste wood down to the second ply or core stock, leaving the ornamentation in relief. Then
soak the plywood in warm water to loosen the glue and free the fretwork, which will
require only a little sandpapering before it is applied to the model. It should, of
course, be dried before applying it. Delicate designs also can be made by burning through
1/16-in. plywood with a hot needle (Fig. 35). The shank of the needle can be ground to
conform to the general shape and design of the tiny angles that go to make up the
figures.
Small Boats
Many ship models require a number of small boats. Although these can
be cut from solid blocks of soft wood, such a procedure requires careful, time-consuming
shaping. A simpler way, that is equally effective, is to make them of stiff cardboard as
in Fig. 36. With a little practice, you will be able to cut the blanks to just the right
shape to give the required length, beam, and curve. The two ends of the boats can be bound
with paper, glued in place. If keels, oars, and rudders are desired, they also can be
simulated with cardboard. When finished with a coat of paint, they give the effect of
"in-scale" sturdiness combined with lightness that is so important in accurate models.