Machinery's Handbook, 31st Edition
V-BLOCK CALIBRATION 747 19) Indicate the top surface of the V-block and confirm the flatness of the block. If there are any erroneous readings, immediately check the V-block base for nicks or burrs that could be affecting the reading. Gently remove nicks or burrs with a hard Arkansas stone. 20) Move the contact point to V-Block 2. Do not change the zero setting and indicate the top surface of V-Block 2 and confirm that the readings are within the tolerance limits as defined in Table 11 for matched sets. 21) Rotate the UUT set so that Side A is now on the surface plate and place the contact point in the same relative position as with the TOP measurement.
Starting Point
V-Block 1 V-Block 2 Fig. 14. Matched V-Block Setup TOP VIEW 22) Indicate the entire surface of V-Block 1, once again observing for any abnormalities that may indicate a nick or burr on the side opposite. 23) Move the contact point to the starting point on V-Block 2 and observe the deviation from the zero setting. Indicate the entire surface of V-Block 2 and note the maximum deviation from zero. 24) Verify that all readings are within the tolerance limits as defined in Table 11. 25) Rotate the UUT set so that the TOP is now on the surface plate. 26) Place the contact point in the same relative starting position as previously used. If the V-Block Set has a lapped or flat ground surface, indicate the entire surface observing any abnormalities and deviations in accordance with the tolerance table. If the UUT has a double rail supporting system, only indicate the sections that come into contact with the surface plate under normal use. 27) Move the contact point to V-Block 2 starting point and observe the initial deviation from zero. Indicate the applicable surface area and verify that all deviations are within the tolerance limits as defined in Table 11. 28) Rotate the UUT set to the final side and repeat Items 21) through 24). 29) Place UUT set on End A and repeat Items 21) through 24). 30) Place UUT set on End B and repeat Items 21) through 24). V-Groove Centrality.— 1) The V-Groove Centrality is not calibrated in all types and styles. Centrality of the V-Groove is only applicable if the V-block can be set on its side with no interference when the clamp or yoke is installed. a) Precision granite V-blocks are generally produced in laboratory grade accuracies and require special attention in handling to avoid damage to the standards and V-blocks. b) Type 1 Style 5 are sometimes large and require special care in handling due to the weight of the UUT and the size of the standard use in this calibration. Care must be taken when securing a large cylindrical square into the V-groove so no nicks or burrs are raised in the lapped surface. 2) Using the same cylindrical gage or cylindrical square as in Parallelism of V to Base : Items through 13), lay the UUT on Side A as shown in Fig. 15. 3) Place the contact point on top of the cylindrical gage close to the end of the V-block. Seek the top of the Cylinder by sweeping across the radius and observing the maximum indication. Zero the electronic indicator.
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