Page 131 - CITS - Fitter Trade Pactical - Volume - 2
P. 131
FITTER - CITS
Applications of Thread Micrometer
Measurement of Pitch Diameter:
The three-wire method: This method uses three wires of the same diameter for checking the effective diameter
and the flank form. The wires are finished with a high degree of accuracy.
The size of the wires used depends on the pitch of the thread to be measured.
For measuring the effective diameter, three wires are suitable placed between the threads.
The measuring wires are fitted in wire-holders which are supplied in pairs. One holder has provisions to fix one
wire and the other for two wires.
While measuring the screw thread, the holder with the one wire is placed on the spindle of the micrometer and the
other holder with two wires is fixed on the anvil.
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CITS : CG & M - Fitter - Exercise 37
