DIAL AND VERNIER CALIPERS

Transcription

1 TECHNICAL MANUAL INSTRUMENT CALIBRATION PROCEDURE DIAL AND VERNIER CALIPERS THIS PUBLICATION SUPERSEDES NAVAIR 17 20MD 07 DATED 1 JUNE 1995 DISTRIBUTION STATEMENT C. DISTRIBUTION AUTHORIZED TO U.S. GOVERNMENT AGENCIES AND THEIR CONTRACTORS TO PROTECT PUBLICATIONS REQUIRED FOR OFFICIAL USE OR FOR ADMINISTRATIVE OR OPERATIONAL PURPOSES ONLY. OTHER REQUESTS FOR THIS DOCUMENT SHALL BE REFERRED TO NAVY MEASUREMENT SCIENCE DIRECTORATE, NAVAL WARFARE ASSESSMENT DIVISION, P.O. BOX 5000 CORONA, CA DESTRUCTION NOTICE FOR UNCLASSIFIED, LIMITED DOCUMENTS, DESTROY BY ANY METHOD THAT WILL PREVENT DISCLOSURE OF CONTENTS OR RECONSTRUCTION OF THE DOCUMENT. PUBLISHED BY DIRECTION OF COMMANDER NAVAL AIR SYSTEMS COMMAND 1 FEBRUARY 1997

2 LIST OF EFFECTIVE PAGES The purpose of this list is to identify the pages in this document affected by any technical content changes made since the previous release of the document. NOTE: On a revised page, with the exception of the Title, the A, and the i pages, the technical changes are indicated by a vertical line in the outer margin of the page. Page No. Revision* Page No. Revision* Page No. Revision* Title A R R i 0 1, R 4 to (blank) (blank) (blank) (blank) (blank) 0 19 to (blank) (blank) 0 A 1 0 B 1 0 * Zero in this column indicates an original page. R in this column indicates a revised page. A

3 TABLE OF CONTENTS Section Page 1 Introduction and Description Equipment Requirements Preliminary Operations Calibration Process Outside Dimension Scale/Dial Zero Indication Check Outside Dimension Scale Indication Test Inside Dimension Scale Indication Test Depth Gage Indication Test Dial Indicator Tests Navy Calibration Checklist Appendix A: Representative Test Instruments A 1 Appendix B: English/Metric Conversion Tables B 1 ILLUSTRATIONS Figure Page 1 Outside Dimension Scale Indication Test Configuration Inside Dimension Scale Indication Test Configuration Depth Gage Indication Test Configuration TABLES Table Page 1 Calibration Description Vernier Caliper Dimension Scale Points Dial Caliper Dimension Scale Points i

4 SECTION 1 INTRODUCTION AND DESCRIPTION 1.1 This procedure describes the calibration of Dial and Vernier Calipers capable of measuring inside and outside dimensions from 0 to 72 inches, and depth dimensions from 0 to 12 inches. The vernier caliper consists of a graduated beam with a pair (or pairs) of jaws with parallel measuring surfaces. The jaw measuring surfaces are perpendicular to the beam, with one jaw adjustable. The adjustable jaw may have a rod attached perpendicular to its measuring surface for use as a depth gage. The graduated jaw may have a single scale for all measurements, or it may have separate scales. Vernier height gages and dial caliper gages (of the type used to measure hole diameters) are excluded from this procedure. Instruments that may be calibrated by this procedure include, but are not limited to, the models listed in Appendix A. The instrument being calibrated is referred to herein as the TI (Test Instrument). 1.2 All comments concerning this procedure should be directed to Navy Measurement Science Directorate, Naval Warfare Assessment Division, P.O. Box 5000, Corona, CA This procedure includes tests of essential performance parameters only. Any malfunction noticed during calibration, whether specifically tested for or not, should be corrected. TI Characteristics Outside dimension scale/dial zero indication Outside dimension scale indication Inside dimension scale indication Depth gage indication Dial indicator Table 1. Calibration Description Performance Specifications Range: 0 to 72 in. Tolerance: in. Range: 0 to 72 in. Tolerance: in./6 in. or in./ft. Range: 0 to 72 in. Tolerance: in./6 in. or in./ft. Range: 0 to 12 in. Tolerance: in. Range: 0 to 2 in. Tolerance: +1 div. per each 6 in. of TI length Test Method Determined by sliding the TI jaws together and reading the indication. Comparison to gage block dimensions, placing the blocks between the TI jaws. Comparison to gage block dimensions, placing the blocks with attached caliper jaws outside of the TI jaws. Comparison to gage block dimensions, placing the TI depth gage rod alongside the gage block and reading the TI outside dimension scale. Comparison to gage block dimensions, setting up the blocks for outside or inside measurements, as applicable. 1

5 SECTION 2 EQUIPMENT REQUIREMENTS NOTE Minimum use specifications are the principal parameters required for performance of the calibration, and are included to assist in the selection of alternate equipment, which may be used at the discretion of the using laboratory. Satisfactory performance of alternate items shall be verified prior to use. All applicable equipment must bear evidence of current calibration. The instruments utilized in this procedure were selected from those known to be available at Navy calibration facilities, and the listing by make or model number carries no implication of preference, recommendation, or approval for use by other agencies. It is recognized that equivalent equipment produced by other manufacturers may be capable of equally satisfactory performance in this procedure. Item 2.1 Square (Hoke) gage block sets with accessories Minimum Use Specifications Range: to 72.0 inches Uncertainty: +10 microinches or +10 microinches/inch of length, whichever is greater Style 2, Grade 2 (formerly Grade+ A), per Fed. Spec. GGG G 15B Calibration Equipment Pratt and Whitney No. 8, 28, or 88; or Webber SS88A1, SS28A1, or SS8A1X SECTION 3 PRELIMINARY OPERATIONS 3.1 PRELIMINARY CONDITIONS Ensure that the work area is clean, well illuminated, free from excessive drafts, free from excessive humidity, and that the rate of temperature change does not exceed 2 F per hour Ensure that the calibration equipment is clean and that the TI and the applicable calibration equipment have been allowed to stabilize at the ambient temperature If a checklist is not provided for the TI, select the calibration points as follows: (for metric TIs, refer to the English/metric conversion tables listed in Appendix B) If the TI measures 12 inches or less, use the applicable values listed in tables 2 and 3 for outside dimension points. Use the values listed in tables 2 and 3 for inside dimension points If the TI measures more than 12 inches, use the values specified in tables 2 and 3, as applicable, and in addition, select points approximately at one half of fullscale and at fullscale. 2

6 NOTE If the TI has both an English and a metric scale, select the points so that the scale markings are within inch of one another to allow simultaneous observations. For example, the English setting inch differs from the metric setting mm by only inch; this negligible error will not affect the calibration. 3.2 PRELIMINARY INSPECTION Ensure that the TI is clean and free from obvious damage, such as nicks and burrs, that would impair its operation Loosen the TI sliding jaw thumb screw and if applicable, the adjusting nut carrier thumb screw. Ensure that the sliding jaw can be moved smoothly along the full length of the beam; if not, take corrective action If the TI is a dial caliper gage, operate the TI over its full range 2 to 3 times and ensure that the TI jaws move smoothly over the full range Clean the TI jaws by closing them on a piece of clean, dry paper, then slowly pulling the paper from between the jaws Slide the TI jaws together and tighten the sliding jaw thumb screw. While holding the TI in front of a strong light, verify that no light is visible along the entire length of the jaw measuring surfaces. If light is visible, take corrective action. SECTION 4 CALIBRATION PROCESS NOTE Unless otherwise specified, verify the results of each test and take corrective action whenever the test requirement is not met, before proceeding. 4.1 OUTSIDE DIMENSION SCALE/DIAL ZERO INDICATION CHECK Slide the TI jaws together and tighten the sliding jaw thumb screw. Record the outside dimension scale indication. NOTE To aid in reading the TI vernier scale, a low power magnifier such as the Bausch & Lomb Vernier Magnifier # can be used Ensure that the value recorded in the preceding step is within to inch If the TI is a dial caliper with an adjustable bezel, adjust it for an exact zero indication within to inch. 3

7 4.2 OUTSIDE DIMENSION SCALE INDICATION TEST NOTE Cotton gloves should be worn when handling gage blocks to prevent the transfer of body heat, and to protect the gaging surfaces Using the TI outside dimension measuring jaws (or surfaces) and a 0.5 inch gage block (item 2.1), prepare to measure the first standard dimension listed in Table 2 or 3, as applicable Position the TI outside dimension measuring jaws against the gage block gaging surfaces as shown in Figure 1. OUTSIDE Figure 1. Outside Dimension Scale Indication Test Configuration NOTE For additional information on the proper operation and application of the TI, refer to NAVAIR 17 35MTM 1, Care, Use, and Maintenance of Measuring Tools Ensure that the TI outside dimension measuring jaws are squarely placed against the gage block gaging surfaces. Make the final adjustment with the sliding jaw thumb screw snug (but not tight), then lock the fine adjusting nut carrier and adjust the fine adjusting nut for the proper feel. Tighten the sliding jaw thumb screw, and record the outside dimension scale indication on the calibration checklist Verify that the value recorded in the preceding step is within the applicable tolerance limits shown in table 2 or 3, as applicable Perform steps through for each of the remaining calibration points listed in table 2 or 3, as applicable, within the range of the TI. 4

8 NOTE If more than one gage block is required to obtain the required dimension, wipe the gaging surfaces clean, and wring the gage blocks together. Secure the gage blocks using the appropriate tie rod and flat headed screws. When measuring the longer length gage blocks, it is recommended that the gage blocks be placed on a stable, flat surface (such as a surface plate) so that both gaging surfaces are exposed If the TI range is greater than the ranges covered in table 2 or 3, as applicable, select and wring together gage blocks to obtain dimensions equal to the TI range at midscale and fullscale, and as selected in step Standard Dimension (in.) Table 2. Vernier Caliper Dimension Scale Points Tolerance Limits (in.) to to to * to to to to to Standard Dimension (in.) Table 3. Dial Caliper Dimension Scale Points Tolerance Limits (in.) to to to * to to to to to *Use in. if the TI range is too limited Perform steps through for the required TI calibration points. Generally, a tolerance of in/ft applies to vernier calipers, and in/6 in. length applies to dial calipers. 4.3 INSIDE DIMENSION SCALE INDICATION TEST Using the TI inside dimension measuring jaws (or surfaces) and a 0.5 inch gage block with caliper jaws attached, prepare to measure the first standard dimension listed in table 2 or 3, as applicable Clean the gaging surfaces of the 0.5 inch gage block and the gage block caliper jaws (supplied as an accessory to the gage block set), and wring them together. Secure the gage block and caliper jaws assembly using the appropriate tie rod screws. 5

9 4.3.3 Position the TI inside dimension measuring jaws against the inside gaging surface of the gage block caliper jaws approximately as shown in Figure 2. INSIDE Figure 2. Inside Dimension Scale Indication Test Configuration Ensure that the TI inside dimension measuring jaws are squarely placed against the gaging surfaces of the gage block caliper jaws. Make the final adjustment as in step 4.2.3, and record the inside dimension scale indication on the checklist. NOTE If the TI design is such that only one pair of jaws are used, and the same scale is employed for both inside and outside dimension measurements, the thickness of the measuring nibs must be added to the indication obtained in step 4.3.4; then record the total of the indication and the nib thickness Verify that the value recorded in the preceding step is within the applicable tolerance limits shown in table 2 or 3, as applicable If the TI inside and outside dimension scales are the same, skip to step 4.3.8; if not, perform step Perform steps through for each of the remaining calibration points listed in table 2 or 3, as applicable, within the range of the TI If the TI range is greater than the ranges covered in table 2 or 3, as applicable, select and wring together gage blocks to obtain dimensions equal to the TI range at midscale and fullscale, and as selected in step Perform steps through for the required TI calibration points. Generally, a tolerance of in/ft applies to vernier calipers, and in/6 in. length applies to dial calipers If the TI has a built in depth gage, skip to section

10 If the TI has no depth gage but has a dial, skip to section If no other measurements are to be performed, disconnect and secure the equipment. 4.4 DEPTH GAGE INDICATION TEST Clean the gaging surfaces of the 1.0 inch gage block and the triangular base (supplied as an accessory to the gage block set), and wring them together. Secure the gage block and base assembly using the appropriate tie rod and flat headed screws Position the end of the TI beam against the gage block gaging surface with the end of the depth gage rod against the gage block triangular base as shown in Figure 3. ÉÉÉÉÉÉÉÉÉÉÉÉÉ Figure 3. Depth Gage Indication Test Configuration Ensure that the TI depth gage measuring surfaces are squarely placed against the gaging surfaces of the gage block and the triangular base Make the final adjustment as in step 4.2.3, and record the outside dimension scale indication on the checklist If the TI has a dial with a 1 inch range, record the dial indication on the checklist Verify that the value(s) recorded in the preceding step(s) is/are within to inch If applicable, perform steps through for each additional inch of depth gage range, changing gage blocks as necessary If the TI has a dial, skip to section 4.5. If no other measurements are to be performed, disconnect and secure the equipment. 7

11 4.5 DIAL INDICATOR TESTS If the TI dial indicator graduations are plus and minus from 0, skip to step 4.5.2; if the graduations are continuous around the dial, perform the following steps: Determine the gage blocks required to obtain a TI dial indication at approximately 25%, 50%, 75%, and 100% of the dial range using the major graduations as the calibration points Ensure that the TI dial indicates 0. If the TI covers only a specific range such as 1.60 to 2.00 inches, ensure that the TI dial indicates the minimum nominal value (in this case 1.60 inches) when the TI jaws are adjusted for a minimum indication. Adjust the TI bezel if necessary If the TI measures inside dimensions, attach caliper jaws to the ends of the selected gage block stacks. Insert the TI jaws between the gage block caliper jaws, in turn. Verify that each indication is within the tolerance limits If the TI measures outside dimensions, insert the selected gage blocks, in turn, between the TI jaws. Verify that each indication is within tolerance limits If the TI indicator graduations are plus and minus from 0, perform the following steps: Determine the gage blocks required to obtain a TI dial indication in each direction from 0 on the dial to the range of the dial. For example, if the TI dial range is from 0 to inch, select gage block sizes of 0.100, 0.110, 0.120, 0.125, 0.130, 0.140, and inch. The inch block is for setting zero Insert the gage blocks to obtain a zero indication, and adjust the TI dial bezel as necessary Insert the gage blocks, in turn, between the TI jaws to obtain a TI dial indication in the plus direction at each calibration point. Verify that each calibration point is within the tolerance limits Insert the gage blocks, in turn, between the TI jaws to obtain a TI dial indication in the minus direction at each calibration point. Verify that each calibration point is within the tolerance limits If no other measurements are to be performed, disconnect and secure the equipment. 8

12 CALIBRATION CHECKLIST TEST INST (S) Starrett Non Dial Vernier Caliper PROC. NO. PROCEDURE STEP NO. (1) NA 17 20MD 07 FUNCTION TESTED (2) MFG. MODEL SER. NO. NOMINAL (3) MEASURED VALUES FIRST RUN SECOND RUN (4) (5) OUT OF CALIBRATION TOLERANCES TOL (6) (7) 3.2 Preliminary Inspection TI inspection ck ( ) NA Smooth operation ck ( ) NA Jaws parallel ck ( ) NA 4.1 Outside Dimension Scale/Dial Zero Indication Check TI vernier zero ck ( ) NA to Outside Dimension Scale Indication Test TI scale indication to to to to to to to Inside Dimension Scale Indication Test TI scale indication to Page 1 of 1 ( 10 blank) 9

13 CALIBRATION CHECKLIST TEST INST (S) Starrett 122 6, Scherr Tumico and 75 6, and Brown & Sharpe 571 6, Vernier Calipers PROC. NO. PROCEDURE STEP NO. (1) NA 17 20MD 07 FUNCTION TESTED (2) MFG. MODEL SER. NO. NOMINAL (3) MEASURED VALUES FIRST RUN SECOND RUN (4) (5) OUT OF CALIBRATION TOLERANCES TOL (6) (7) 3.2 Preliminary Inspection TI inspection ck ( ) NA Smooth operation ck ( ) NA Jaws parallel ck ( ) NA 4.1 Outside Dimension Scale/Dial Zero Indication Check TI vernier zero ck ( ) NA to Outside Dimension Scale Indication Test TI scale indication to to to to Inside Dimension Scale Indication Test TI scale indication to Page 1 of 1 ( 12 blank) 11

14 CALIBRATION CHECKLIST TEST INST (S) Starrett Vernier Caliper PROC. NO. PROCEDURE STEP NO. (1) NA 17 20MD 07 FUNCTION TESTED (2) MFG. MODEL SER. NO. NOMINAL (3) MEASURED VALUES FIRST RUN SECOND RUN (4) (5) OUT OF CALIBRATION TOLERANCES TOL (6) (7) 3.2 Preliminary Inspection TI inspection ck ( ) NA Smooth operation ck ( ) NA Jaws parallel ck ( ) NA 4.1 Outside Dimension Scale/Dial Zero Indication Check TI vernier zero ck ( ) NA to Outside Dimension Scale Indication Test TI scale indication to to to to to to to to Inside Dimension Scale Indication Test TI scale indication to to to to to to to to Page 1 of 1 ( 14 blank) 13

15 CALIBRATION CHECKLIST TEST INST (S) Starrett Vernier Caliper PROC. NO. PROCEDURE STEP NO. (1) NA 17 20MD 07 FUNCTION TESTED (2) MFG. MODEL SER. NO. NOMINAL (3) MEASURED VALUES FIRST RUN SECOND RUN (4) (5) OUT OF CALIBRATION TOLERANCES TOL (6) (7) 3.2 Preliminary Inspection TI inspection ck ( ) NA Smooth operation ck ( ) NA Jaws parallel ck ( ) NA 4.1 Outside Dimension Scale/Dial Zero Indication Check TI vernier zero ck ( ) NA to Outside Dimension Scale Indication Test TI scale indication to to to to Inside Dimension Scale Indication Test TI scale indication to to to to Page 1 of 1 ( 16 blank) 15

16 CALIBRATION CHECKLIST TEST INST (S) Fowler Dial Caliper PROC. NO. PROCEDURE STEP NO. (1) NA 17 20MD 07 FUNCTION TESTED (2) MFG. MODEL SER. NO. NOMINAL (3) MEASURED VALUES FIRST RUN SECOND RUN (4) (5) OUT OF CALIBRATION TOLERANCES TOL (6) (7) 3.2 Preliminary Inspection TI inspection ck ( ) NA Smooth operation ck ( ) NA Jaws parallel ck ( ) NA 4.1 Outside Dimension Scale/Dial Zero Indication Check TI vernier zero ck ( ) NA Adj. to as necessary 4.2 Outside Dimension Scale Indication Test TI scale indication to to to to Inside Dimension Scale Indication Test TI scale indication to Depth Gage Indication Test TI scale indication to Dial Indicator Tests TI dial zero ck ( ) NA Adj. to as necessary TI dial indication to to to to Page 1 of 1 ( 18 blank) 17

17 CALIBRATION CHECKLIST TEST INST (S) Fowler Dial Caliper PROC. NO. PROCEDURE STEP NO. (1) NA 17 20MD 07 FUNCTION TESTED (2) MFG. MODEL SER. NO. NOMINAL (3) MEASURED VALUES FIRST RUN SECOND RUN (4) (5) OUT OF CALIBRATION TOLERANCES TOL (6) (7) 3.2 Preliminary Inspection TI inspection ck ( ) NA Smooth operation ck ( ) NA Jaws parallel ck ( ) NA 4.1 Outside Dimension Scale/Dial Zero Indication Check TI vernier zero ck ( ) NA Adj. to as necessary 4.2 Outside Dimension Scale Indication Test TI scale indication to to to to to to Inside Dimension Scale Indication Test TI scale indication to Depth Gage Indication Test TI scale indication to Dial Indicator Tests TI dial zero ck ( ) NA Adj. to as necessary Page 1 of 2 19

18 CALIBRATION CHECKLIST TEST INST (S) Fowler Dial Caliper PROC. NO. PROCEDURE STEP NO. (1) NA 17 20MD 07 FUNCTION TESTED (2) MFG. MODEL SER. NO. NOMINAL (3) MEASURED VALUES FIRST RUN SECOND RUN (4) (5) OUT OF CALIBRATION TOLERANCES TOL (6) (7) TI dial indication to to to to Page 2 of 2

19 CALIBRATION CHECKLIST TEST INST (S) Mitutoyo Mfg Dial Snap Caliper PROC. NO. PROCEDURE STEP NO. (1) NA 17 20MD 07 FUNCTION TESTED (2) MFG. MODEL SER. NO. NOMINAL (3) MEASURED VALUES FIRST RUN SECOND RUN (4) (5) OUT OF CALIBRATION TOLERANCES TOL (6) (7) 3.2 Preliminary Inspection TI inspection ck ( ) NA Smooth operation ck ( ) NA Jaws parallel ck ( ) NA 4.1 Outside Dimension Scale/Dial Zero Indication Check TI vernier zero ck ( ) NA Adj. to as necessary 4.2 Outside Dimension Scale Indication Test TI scale indication to to to to Inside Dimension Scale Indication Test TI scale indication to to to to Depth Gage Indication Test TI scale indication to Dial Indicator Tests TI dial zero ck ( ) NA Adj. to as necessary Page 1 of 2 21

20 CALIBRATION CHECKLIST TEST INST (S) Mitutoyo Mfg Dial Snap Caliper PROC. NO. PROCEDURE STEP NO. (1) NA 17 20MD 07 FUNCTION TESTED (2) MFG. MODEL SER. NO. NOMINAL (3) MEASURED VALUES FIRST RUN SECOND RUN (4) (5) OUT OF CALIBRATION TOLERANCES TOL (6) (7) Plus direction TI dial indication to to to Minus direction TI dial indication to to to Page 2 of 2

21 CALIBRATION CHECKLIST TEST INST (S) Brown & Sharpe 577 or Vernier Caliper PROC. NO. PROCEDURE STEP NO. (1) NA 17 20MD 07 FUNCTION TESTED (2) MFG. MODEL SER. NO. NOMINAL (3) MEASURED VALUES FIRST RUN SECOND RUN (4) (5) OUT OF CALIBRATION TOLERANCES TOL (6) (7) 3.2 Preliminary Inspection TI inspection ck ( ) NA Smooth operation ck ( ) NA Jaws parallel ck ( ) NA 4.1 Outside Dimension Scale/Dial Zero Indication Check TI vernier zero ck ( ) NA to Outside Dimension Scale Indication Test (mm.) (mm.) (mm.) TI scale indication to to to to Inside Dimension Scale Indication Test TI scale indication to to to to Page 1 of 1 ( 24 blank) 23

22 CALIBRATION CHECKLIST TEST INST (S) S T Industries Vernier Caliper PROC. NO. PROCEDURE STEP NO. (1) NA 17 20MD 07 FUNCTION TESTED (2) MFG. MODEL SER. NO. NOMINAL (3) MEASURED VALUES FIRST RUN SECOND RUN (4) (5) OUT OF CALIBRATION TOLERANCES TOL (6) (7) 3.2 Preliminary Inspection TI inspection ck ( ) NA Smooth operation ck ( ) NA Jaws parallel ck ( ) NA 4.1 Outside Dimension Scale/Dial Zero Indication Check TI vernier zero ck ( ) NA to Outside Dimension Scale Indication Test TI scale indication to to to to Inside Dimension Scale Indication Test TI scale indication to Depth Gage Indication Test TI scale indication to to to to to to Page 1 of 1 ( 26 blank) 25

23 APPENDIX A REPRESENTATIVE TEST INSTRUMENTS TIs which may be calibrated using this procedure include, but are not limited to, the following: Model Manufacturer Model Manufacturer CM6422A Central Tool 375 ( ) Scherr Tumico D6 Helios DC 8 Nippon Sukutei DC ( ) L.S. Starrett HD ( ) Helios 504 Mitutoyo Mfg VC ( ) 505 VCS Fowler VFF Scherr Tumico Scherr Tumico Fowler 122 ( ) L.S. Starrett Helios 122EM ( ) M ( ) S T Industries Mitutoyo Mfg 123EM ( ) M Scherr Tumico 570 ( ) Brown & Sharpe ( ) 160 Mitutoyo Mfg Scherr Tumico ( ) ( ) ( ) Peacock 6941 Swiss Prec. Inst DoAll Scherr Tumico Swiss Prec. Inst A 1

24 APPENDIX B ENGLISH/METRIC CONVERSION TABLES Table B 1. Tolerance Limit Conversions (Rounded) Millimeters Inches Table B 2. Test Point Conversions (Rounded) Millimeters Inches Millimeters Inches Millimeters Inches B 1