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Aviation Boatswains Mate E 3 & 2 - Aviation theories and other practices | Next
TWIST DRILLS |
Figure 1-31.-Polishing operations.
you are using sheets of abrasive cloth, tear off a strip
from the long edge of the 8- by 11-inch sheet.
Wrap the cloth around the file (fig. 1-31, view A)
and hold the file as you would for drawfiling. Hold
the end of the cloth in place with your thumb. In
polishing, apply a thin film of lubricating oil on the
Figure 1-32.-File card/brush cleaner.
surface being polished and use a double stroke with
pressure on both the forward and the backward
strokes. Note that this is different from the drawfiling
stroke in which you cut with the tile in only one
direction.
When further polishing does not appear to
improve the surface, you are ready to use the next
finer grade of cloth.
Before changing to the finer
grade, however, reverse the cloth so that its back is
toward the surface being polished.
Work the reversed cloth back and forth in the
abrasive-laden oil as an intermediate step between
grades of abrasive cloth. Then, with the solvent
available in your ship, clean the job thoroughly before
proceeding with the next finer grade of cloth. Careful
cleaning between grades helps to ensure freedom from
scratches.
For the final polish, use a strip of crocus
cloth – first the face and then the back – with plenty of
oil. When polishing is complete, again carefully clean
the job with a solvent and protect it with oil or other
means, from rusting.
In figure 1-31, A of view B shows another way to
polish, in which the abrasive cloth is wrapped around
a block of wood. In B of view B, the cloth has
simply been folded to form a pad, from which a worn,
dull surface can be removed by simply tearing it off
to expose a new surface.
POLISHING ROUND-METAL STOCK. –In
figure 1-31, view C, a piece of round stock is being
polished with a strip of abrasive cloth, which is
“seesawed” back and forth as it is guided over the
surface being polished.
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