Using The 6V7899 Size Setting Fixture Group{651} Caterpillar

The 6V7899 Size Setting Fixture Group can be used to check or calibrate the 6V7898 Dial Bore Gauge Group. See Special Instruction Form SMHS8253 for information on how to use this dial bore gauge.

Components Of The 6V7899 Size Setting Fixture Group

1 - Storage Case.

2 - Master Standard (for checking accuracy of fixture).

3 - Setting Fixture.

4 - Magnifier.

5 - Anti-rust Compound.

6 - Setting Standard, 50-75 mm Range.

7 - Setting Standard, 75-100 mm Range.

8 - Setting Standard, 100-125 mm Range.

9 - Setting Standard, 125-150 mm Range.

10 - Setting Standard, 150-175 mm Range.

11 - Hex Wrench.

12 - Spanner Wrench.

13 - Adapter Plate -- For use when Setting Early Style Dial Bore Gauge (has "Made in England" Stamped on Extension Sleeve).

Using The 6V7899 Size Setting Fixture Group

1 The following procedure shows how to calibrate 6V7898 Dial Bore Gauge (1) with size setting fixture (2). It is not necessary to remove fixture (2) from the storage case; however, if it is removed, do not lift the fixture by micrometer head (A).

2 Find the correct setting standard for the diameter size to be checked. For example, if the gauge is to be set to 78.468 mm, the correct setting standard is marked 75.000 + mm. Clean both ends of the setting standard, the V-block and micrometer spindle tip (B). Be sure spindle lock (C) is loose to permit the micrometer to turn freely.

3 Set the micrometer head to the size desired, and lightly tighten spindle lock (C). For example, if the gauge is to be set to 78.468 mm, set the micrometer head to 3.468 mm.

4 Put the correct setting standard in the V-block against the micrometer spindle tip. Install the correct gauge point (3) as far as it will go into the dial bore gauge. Carefully put dial bore gauge (1), with gauge point, in the nest of the size setting fixture.

5 Loosen gauge point (3) until it touches the setting standard (D) and the dial indicator hand moves.

6 With zero (0) on the dial indicator face at approximately the 12 o'clock position (or the position where it is easiest to read) adjust gauge point (3) until the hand of the dial indicator is approximately at zero position. (Do not hold the gauge during this procedure -- the fixture will keep the gauge in a stable position). Tighten gauge point lock nut (4) to hold the gauge point in the adjusted position.

7 Move the gauge back and forth in the horizontal plane until the dial indicator hand shows the "most minus" (-) reading. Move the gauge back and forth in the vertical plane until the dial indicator hand shows the "most minus" (-) reading. Adjust the dial face as necessary to set the pointer exactly at zero while the indicator gauge shows the most minimum reading.

Calibration Of The 6V7899 Size Setting Fixture Group

1 Clean both ends of the master standard, the V-block and the tip of the micrometer spindle.

2 Set micrometer head (1) to approximately 12.800 mm. Put master standard (2) in the V-block and push the end against fixed stop (A). Turn the micrometer until micrometer tip (B) comes in contact with master standard (2).

NOTE: At this time, the micrometer should read exactly 12.500 mm. If it does, no calibration is necessary. If it does not read 12.500 mm, calibration is necessary according to the procedure in steps 4 through 7 following.

3 Tighten spindle lock (3).

4 Use spanner wrench (4) to loosen speeder knob (5).

5 Turn micrometer head (1) until it reads exactly 12.500 mm.

6 Tighten speeder knob (5) finger tight. Loosen spindle lock (3) and back the spindle away from the master standard; hold micrometer head (1) firmly and use spanner wrench (4) to tighten speeder knob (5).

7 Check the new setting. If necessary, start with step 4 and do the adjustment procedure again.

Repair Of The 6V7899 Size Setting Fixture Group

The size setting fixture group should be sent to the manufacturer for service. The master standard and the setting standards can also be sent separately, if needed, to check their accuracy. A letter should be with the returned fixture group, giving a description of the problem and the date of purchase from Caterpillar. Fixture groups less than one year old will be repaired under warranty, except for abuse. The cost of out-of-warranty repairs will be charged to the owner. The gauge group should be sent to the following repair center.