Figure 4-105. Diestocks
Store in a case or wrap dies individually in
cloths where they will not come in contact with other
4-19. Thread Chasers. Thread chasers are threading
tools that have several teeth and are used to rethread
(chase) damaged internal or external threads. These
tools are shown in figure 4-106. The internal thread
chaser has its cutting teeth located on a side face, while
the external thread chaser has its cutting teeth on the
end of the shaft. The handle end of the tool shaft tapers
to a point.
4-20. Screw and Tap Extractors. Screw and tap
extractors are made of hardened steel and are used to
remove broken screws and taps without damaging the
surrounding metal or the threaded hole.
Description. The following paragraphs
describe these tools.
Screw extractors. Some screw extractors,
as shown in figure 4-107, are straight. They have flutes
from end to end. These extractors are available in sizes
to remove broken screws having 1/4 to 1/2 inch outside
diameters. Spiral tapered extractors, shown in figure 4-
108, are sized to remove screws and bolts from 3/16
inch to 2 1/8 inches outside diameter.
Tap extractors. Tap extractors, shown in
figure 4-109, are sized to remove taps with an outside
diameter of 3/16 inch to 2 1/8 inches.
Use The following paragraphs describe the use
of spiral extractors and tap extractors.