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5. OPERATION
5.1.
Setting up (The dial ball gauge is a comparator not a measuring tool)
5.1.1. Measure the bore diameter or gap to be measured to the nearest millimetre with a rule or vernier callipers. The bore or gap
must range between 35mm and 50mm nominally with this tool. (up to 52.5 with spacers)
5.1.2. select the range of parts required, anvils and spacers using the table on the last page as a guide.
5.1.3. Assemble the dial bore gauge with selected parts as shown in fig.1. Ensure all components are clean when assembled, use the
supplied spanner. DO NOT overtighten
5.1.4. Insert the dial stylus into the probe body as shown in fig.4. The stylus will meet with resistance internally and the dial pointer will
begin to rotate clockwise. one complete cycle of the pointer is recommended for registration and will be indicated by the secondary dial
indicator annotated 1-5. The small pointer should now be indicating "1" [one].
5.1.5. Clamp the dial stem with the thumb screw. DO NOT overtighten.
Be aware, nib projection is 2mm.
Aim for 0.5mm to 1.5mm as the
measurement zone.
fig.2
Anvil
spacer
nib
fig.1
5.2.
Calibration
5.2.1. depending upon accuracy requirement, calibration can be achieved with slip gauges, micrometer or vernier calipers. In our instructions
example the micrometer is suggested, which has similar accuracy to the dial gauge.
5.2.2. set the micrometer (25mm-50mm) to the target size "x", for example Ø45.75 and lock. In our example the tolerance required is H9 from
Bs 4500:1969 (+.062/-0).
5.2.3. From instruction 5.1.2 and the tables on the back page; parts required are the anvil 44 plus spacer ring 2, from item 1 in fig.5.
Assemble as shown above in fig.1.
5.2.4. Maneouvre the gauge anvil and nib inside the measuring gap of the micrometer (fig.11). This activity could be eased by assistance or
carefully clamping the probe in a retort stand or similar.
5.2.5. observe the large dial pointer movement. It is essential that the axis of the gauge anvil and spring loaded nib are centralised in the
micrometer measuring faces. It is essential to observe the total sweep of the dial pointer using the small dial. remember from the initial
setting the pointer had rotated one full cycle.
5.2.6. When satisfied with alignment, hold the position and rotate the dial bezel until the "0" [zero] aligns with the pointer. lock the bezel with
the thumb screw. Your dial bore gauge has now been calibrated for use in a Ø45.25 to Ø46.25 bore ie +/-0.5mm of target.
5.2.7. The tolerance band can now be set using the two "markers" on the bezel. our example states the tolerance band to be +0.062 to -0. set
one marker opposite and in line with "0" [zero] (fig.6) and the other +6.2 (fig.7) divisions apart. note! the larger the deflection the smaller
the bore.
Pass
Fail
© Jack sealey limited
fig.3
Fail
fig.6
lower limit (+0.00mm)
Example only; taken from
Calibration text 5.2.
Original Language Version
small pointer on "1"
Insert the stylus for 1 full large pointer revolution
fig.5
use the spacer rings to achieve "x" = 36, 37, 39, 40, 42 etc..
Pass
Fail
Tolerance
markers
fig.4
Fail
fig.7
upper limit (+0.062mm)
dBG509
Issue: 1 - 21/06/15
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