INSIDE MICROMETERs WITH JAWS Inside Micrometers Machinery's Handbook, 31st Edition
776
Type II, Class 1, Inside.— The Type II, Class 1, Inside Micrometer with Jaws shall appear similar in design to Fig. 12 and conform to parameters and accuracy as defined in Table 3. Table 3. Type II, Class 1, Inside Micrometer with Jaws Size Range Tolerance Radial Alignment (in.) (in.) (in.) (in.) 1 0.200 to 1 0.0002 0.003 1 1 ⁄ 2 0.500 to 1 1 ⁄ 2 0.0002 0.003 2 1 to 2 0.0002 0.003
Vernier Type Jaws
Spindle
Barrel
Thimble
Jaw Adjusment Screw
20 0
0 9 8 7
Graduations Reference Line Spindle Lock Screw Positioning and Guide Slot
Jaw Lock Screw
Fig. 12. Type II, Class 1: Inside Micrometer with Jaws Design : The inside micrometer with jaws shall have a vernier-caliper style measuring jaw, micrometer screw, spindle, barrel and thimble, knurled lock screw, lock device and adjusting screw. Jaws : The inside micrometer vernier-caliper style jaws shall be designed so the measur ing surfaces remain parallel throughout the entire range of measurement. The jaws shall travel parallel to the axis of the spindle travel and in the same plane. Micrometer Screw: The Type II, Class 1 inside micrometer shall be driven by a micrometer screw with a lead accuracy throughout its entire length of travel that will permit conformance to the tolerance defined in Table 3. The micrometer screw shall in all aspects adhere to the requirements and performance parameters previously defined for the Micrometer Screw Spindle on page 767. Spindle: The Type II, Class 1 inside micrometer shall have a spindle that is not an integral part of the Micrometer Screw. The spindle shall be designed to have only longitudinal movement in the barrel while the micrometer screw is secured to the thimble and free to rotate on the connection to the spindle. The spindle shall have a good free moving fit in the barrel bearing with no shake or bind and shall move smoothly throughout its entire length of travel. The spindle is secured from rotation and guided by the positioning guide and slot. Barrel and Thimble: The barrel and thimble of the Type II, Class 1 inside micrometer shall conform to the design requirements as defined in the previous section Type I, Caliper Micrometer . The design requirements for the applicable graduations shall as well be adhered to with the exception of the vernier scale. The numerals for graduations on the barrel shall read in the opposite direction from those on the conventional Type I micrometers as the measurements are reading an internal measurement that will become smaller as the micrometer spindle is drawn outward and larger as it is turned in. The first and every fourth graduation on the barrel along the longitudinal reference line shall
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