ROD AND SLEEVE INSIDE MICROMETERS Machinery's Handbook, 31st Edition
778
For Type II, Class 2 inside micrometers designed to inch scale: • in the 1 to 2 inch range, graduations shall be from 0 to 0.250 inch on the barrel • in the 2 to 8 inch, and 2 to 12 inch range, graduations will be from 0 to 0.500 inch • in the 8 to 32 or 36 inch range, graduations will be from 0 to 1.000 inch distance For Type II, Class 2 inside micrometer designed to the metric scale: • in the 25 to 50mm range, graduations shall be from 0 to 7mm on the barrel • in the 50 to 200mm, and 50 to 300mm range, graduations will be from 0 to 13mm • in the 200 to 800 or 900mm range, graduations will be from 0 to 25mm on the barrel All Type II, Class 2 micrometer heads shall conform in feature design and finish as pre viously defined in the Type I, Caliper Micrometer general definitions. Micrometer Screw, Barrel and Thimble: The lead of the micrometer screw shall be accurate to within the performance limits as defined in the Manufacturers’ Production Tolerance Tables on page 781 throughout the entire length of travel. The barrel and thimble shall conform to the design definitions as previously outlined in the Type I, Caliper Micrometer section. Measuring Rods and Spacing Collars: A sufficient number of Measuring (length) Rods and Spacing Collars shall be provided to enable the measurement of all distances within the range of each Inside Micrometer Set. The Rods shall be of such design as to provide positive seating with no side motion when assembled with the micrometer head. Length Rods shall provide an adjustable contact point to enable compensation for wear of the measuring face. Each Length Rod shall be plainly, clearly and permanently marked for measurement range. Measuring Faces: The measuring face shall have a radius of curvature less than one- half of the smallest measuring range of the inside micrometer with a surface roughness not to exceed 4 m inch Ra. The locating faces on all spacing collars and length rods and micrometer head ends shall have a surface finish not to exceed 8 m inch Ra. Type II, Class 3, Style A.— The Type II, Class 3, Style A, Tubular Inside Micrometer, Interchangeable Head shall conform to all design feature definitions of the Class 2 inside micrometer with the exception that the length rods shall be tubular in design and conform to the accuracy and length requirements defined in Table 5. The Style A inside micrometer shall follow in design and appear similar to Fig. 14.
0 1 2
0 20 Fig. 14. Type II, Class 3, Style A: Tubular Inside Micrometer with Interchangeable Heads
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