Lesson 4/Learning Event
Thread
a. Center gages check the angle of thread cutting tools, Figure 57.
The gage is also used to check cut threads and the scales are used
to measure the number of threads per inch.
b. Screw pitch gages measure the pitch of screws. If the pitch of a
screw is not known, it can be determined by comparing it with the
standards on various screw pitch gages as shown in Figure 58. Place
a blade of a gage over the threads, and check to see whether it
meshes; if not, successively check each blade of the gage against
the thread until it matches. The pitch can be read off the correct
blade. The blades are made pointed so they can be inserted in small
nuts to check inside threads as well as outside threads.
FIGURE 57.
USING CENTER GAGE
FIGURE 58.
USING SCREW PITCH GAGES.
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