English Vernier Scale

Using Vernier Calipers

Metric Measure Vernier Scale

Measuring Point Allowances

1.000 in.

.400 in.

.025 in.

.011 in. 1.436 in.

The reading on the caliper shown in insert C is 1.436 in. and was obtained by adding four separate "readings." After a little practice you will be able to make these calculations mentally.

Now try to read the settings of the two verniers shown in inserts D and E. Follow the above procedure. You should read 2.350 in. on D and 2.368 in. on E.

To read a metric-measure vernier, note the number of millimeters, and the 0.25 millimeter if the setting permits, that the zero on the vernier has moved from the zero on the scale. Then add the number of hundredths of a millimeter indicated by the line on the vernier that coincides with a line on the scale.

For example, figure 3-31A shows the zero graduation on the vernier coinciding with a 0.5-mm graduation on the scale resulting in a 38.50 mm reading. The reading in figure 3-3IB indicates that 0.08 mm should be added to the scale reading and results in 38.00 mm + 0.50 mm + 0.08 mm = 38.58 mm.

If a vernier caliper is calibrated in either English measure or in metric measure, usually one side will be calibrated to take outside measurements and the other to take inside measurements directly. The vernier plate for inside measurements is set to compensate for the thickness of the measuring points of the tools. But if a vernier caliper is calibrated for both English and metric measure, one of the scales will appear on one side and one on the other. Then it will be necessary, when taking inside measurements over the measuring points, to add certain amounts to allow for their thickness. For example, table 3-1 shows the amounts to be added for various sizes of vernier calipers.

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April 16, 2014