Measurement

Micrometer

Digital Micrometer

Micrometer

The micrometer is used for where accurate measurement (to 1000th of a mm) is required.

Micrometer Parts

Anvil Glass hard and optically flat

Spindle Moves ½ mm for every full rotation of the Sleeve

Spindle Lock Locks spindle in place

Barrel & Sleeve Used to obtain measurements

Ratchet Prevents over tightening (and thus damaging) micrometer

Reading a Micrometer

When reading a Micrometer it is important to remember that one turn of the spindle represents ½ mm.

Vernier Calipers

Named after its inventor the Vernier scale is incorporated in many measuring instruments, the most commonly used of which is the sliding calliper gauge as shown above. These gauges can be used for both internal and external measurement.

Using Vernier Calipers

Vernier Calipers can be used to measure both internal and external dimensions

External Measurement

Internal Measurement

Metric Scale

Imperial Scale

Reading Vernier Calipers

In the illustration above you first read this scale This reads 2.4cm

Then you look along the this scale and find where two lines line up

This adds a further 0.062mm

Add these two figures together to give 2.4 + 0.062 = 2.462cm

Depth Gauge

As shown in the diagram on the left the Depth Gauge can be used to measure the depth of holes

Calipers

Internal Calipers

External Calipers

Calipers can be used to gauge the size of an object. As Calipers have no in built scale all dimensions must be set with a rule (as shown). This makes Calipers less accurate than both the Micrometer and Vernier Calipers

Setting Calipers

The End