Machinery's Handbook, 31st Edition
V-BLOCK CALIBRATION 745 4) Zero the indicator with the electronic fine adjust to set the final zero indication. 5) Remove the granite square master and replace with the UUT (Side A) as shown in Fig. 12. Side A is determined arbitrarily, but once established, must be maintained throughout the procedure to determine the relationship of all sides to each other.
Squareness Checker: Set to Height of V-Block
V-Block (UUT)
Electronic Indicator
Side B
Surface Plate
Side A
Fig. 12. 6) Rotate the Squarol to seek the lowest indication. Verify that the indication is within the tolerance limits for the UUT as defined in Table 11. Record the indication as Side A to Base Squareness. 7) It may be necessary to place a parallel bar or right-angle iron behind the UUT to secure the UUT in place while obtaining indication. This will not affect the accuracy of the measurement as long as the measurement is repeatable and consistent. 8) Reverse the UUT and repeat Items 1) through 6) for Side B. Record indication as Side B to Base Squareness. 9) Rotate UUT 90° clockwise and repeat Item 6) and record indication as End A to Base Squareness. 10) Rotate UUT 180° clockwise and repeat Item 6) and record indication as End B to Base Squareness. 11) The End measurements will not be applicable to all styles and types due to design features. In that case disregard Items 8) and 9). 12) Rotate the UUT so that Side A is down and the indication is of Base to Side A. 13) Repeat Items 6) through 9) for remaining three sides (End A, End B, Top) 14) Rotate the UUT so that Side B is down and the indication is of Base to Side B. 15) Rotate the UUT so End A is down and the indication is Base to End A. 16) Repeat Items 6) through 9)for remaining three sides. (Side A, Side B Top) 17) Repeat process for End B if applicable. 18) All readings must be within limits defined in Table 11. Parallelism of V to Base.— 1) Select the appropriate size precision cylindrical gage or cylindrical square for the UUT being calibrated. The appropriate size gage should contact the V-groove near the center of the working surface. Leave approximately half the length of the cylindrical gage extended over one end of the UUT as shown in Fig. 13. Note: Larger V-blocks will require the use of cylindrical squares of various diameters to accomplish the engagement at the center of the working surface. Special care should be taken in handling these precision standards to avoid nicking or damaging the fine lapped surfaces. Adaptation of the methods used herein can be made to accomplish the calibra- tion of larger V-blocks without reducing confidence levels associated with the readings taken.
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