CALIBRATION OF INSIDE MICROMETERS Table 16. Recommended Test Points for Type II, Class 1, Inside Caliper Micrometer Machinery's Handbook, 31st Edition
797
Size
Range
Recommended Test Points
(in.) (mm)
(in.)
(mm)
(in.)
(mm)
5.10, 10.20, 15.30, 20.40 and 25.00 7.10, 12.20, 17.30, 23.40, and 30.00 25.10, 30.20, 35.30, 40.40, and 50.00
1
25
0.200 to 1 5 to 25 0.210, 0.420, 0.605, 0.815 and 1.000
30 0.500 to 1 1 ⁄ 2
5 to 30 0.510, 0.720, 0.905, 1.115, and 1.500 25 to 50 1.210, 1.420, 1.605, 1.815, and 2.000
1 1 ⁄
2
2
50
1 to 2
Note: a) The micrometer should be tested at zero and full scale.
b) Care must be taken when wringing gage blocks together to achieve the desired size. It is critical to clean the gage blocks thoroughly before wringing and assembling the end blocks to avoid damaging the superior finish of the standard. 3) Assemble the first gage block stack and measure it using the ratchet or friction thimble as described in the Linearity Test (Outside Micrometers) on page 792. Do not rely on feel as the correct and controlled loading of measuring force by the ratchet or friction thimble will give the most accurate and repeatable reading. Several clicks of the ratchet or applying force until the friction thimble slips and assuring the micrometer is gently seated on the gage block stack will give an accurate reading. Gently rock the micrometer to assure that the Nibs are parallel to the gage block end block faces. Repeat the measurement several times to assure the reading is repeatable. The reading must meet the tolerance limits as defined in Table 17, Tolerance column. Table 17. Tolerance Table: Type II, Class 1 Inside Micrometer with Jaws
Size (in.)
Range (in.)
Tolerance (in.) ±0.001
1
0.200 to 1
±0.001
1 1 ⁄
0.500 to 1
1 ⁄
2
2
2 ±0.001 4) Repeat these steps for each remaining gage block stack and record readings for evalu ation or trend analysis. Follow all guidelines of the quality assurance programs in place in regards to recording and retaining all data collected and reporting OOT conditions. 1 to 2
Gage Block Stack with End Blocks
20 0 9 8 7 0
Fig. 26. Measure Gage Block Stack Assembled with End Blocks
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