CALIBRATION OF DEPTH MICROMETERS Machinery's Handbook, 31st Edition
794
View A
TI
Gage Block
Surface Plate
View B
TI
Gage Bloc k
Gage Block
Surface Plate
Fig. 24. Figure 4: Depth Micrometer Base Flatness Measurement 2) Place the UUT on the surface plate and zero against the plate. A calibrated surface plate must be used as it is used to establish the base zero setting and is considered as one of the standards used in the calibration procedure. Record any deviation and assure the reading is within the tolerance limits as defined. 3) Place the first gage block stack (0.210 inch or metric equivalent) on the surface plate and place the UUT on top of the stack. Measure the stack through the center relief hole in the gage block. Observe the reading. Repeat the measurement three times and assure repeatability of the measurement. Verify that the reading is within the tolerance limits. 4) Repeat Item 3) for all remaining gage block stacks. Record all readings. If an OOT condition is discovered, adjust the UUT and repeat the linearity calibration to verify the adjusted accuracy. 5) Repeat Item 2) for all remaining depth rod extensions. For UUT with resolution of 0.0001 in or better, allow gage block stacks that require wringing to assemble to stabilize for one hour for lengths over 8.00inch. Stabilization is not required for single block lengths. Calibration of Micrometer Heads Linearity Calibration.— 1) Select the appropriate gage blocks as defined in the Linearity Test (Outside Micrometers) . As previously the micrometer head will be calibrated at zero to full scale. Clean and wring gage blocks, as appropriate, assuring no dirt or foreign matter is present.
Micrometer Head TI
V-Block
Surface Plate
Fig. 25. Micrometer Head Set Up — Vertical in V-Block
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