For the measurement of 3 or 5 fluted end mills, taps and reamers etc.
Outside diameters can be directly read, or by applying the single wire
method pitch diameters can be measured. Also used for checking out of
roundness in centreless grinding operations. Positive locking clamp and
constant force ratchet. Accuracy: Measuring Faces: 1-15mm /-4 mu m,
5-25mm /-4 mu m, 25-45mm /-5 mu m. Flatness: 0.3 mu m. Parallelism:
(3L/75) mu m. L maximum measuring length. Measurement of Pitch
Diameter: Pitch diameter E is given by the following formulae after
taking the reading 'M' of micrometer by single wire method.
1. Whitworth (55) E (2M - D) - 3.16567d 0.96049P
2. Metric or unified (60) E (2M - D) - 3d 0.866023P.
Where: M 1/2 (M'/0.4472 - 0.2361D). (5 flutes). E Pitch diameter. P
Pitch of tap. D Diameter of tap. d diameter of wire. M' micrometer