239.372
Figure 10-7.-Hand press.
a well-sharpened blade and a secure handle.
DON’T use any knife as a screwdriver, a punch,
or a pry to open can lids. Always cut away from
you, and keep your hands out of the way of the
blade.
To sharpen a knife, use an oilstone and apply
the same basic principle as that used for
sharpening shears. Do NOT sharpen a knife blade
on a grinding wheel because the metal is too thin.
Too much heat is generated for the thickness of
the metal. To sharpen a knife, clean the oilstone
of all gum and dirt accumulation. Put two or three
drops of medium-light oil on the stone. Lay the
knife on the stone with the back of the knife
slightly raised. Draw the knife toward you with
a diagonal stroke from heal to toe with the cutting
edge advancing. Turn the knife over and move
the blade away from you, cutting edge advancing,
moving from heel to toe. Repeat these steps
several times. The edge is sharp if you feel a
decided drag when passing it lightly over a wet
thumbnail. No drag indicates the edge is not
sharp.
MEASURING DEVICES
The ruler, tape measure, and carpenter’s
square, as shown in figure 10-8, are used often
during the repair of fabric and rubber articles.
These may become special tools by adding a
special mark to show a commonly used scale or
measurement. To comply with technical directive
specifications, be sure to exactly measure items
239.373
Figure 10-8.-Measuring devices.
such as the patch overlaps, length of lines on life
rafts, and every other job you do that requires
special measurements.
The 12-inch, plain steel rule is used for laying
out and measuring small work. One side of the
rule, shown in view A of figure 10-8, has one edge
graduated in sixteenths of an inch and the other
edge graduated in eighths of an inch. This is
indicated on the rule by the numbers 16 and 8,
which are stamped into the metal. The opposite
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