Vernier caliper and Micrometer

precision is the quality of being sharply or clearly defined or how closely the indicated value matches the true value the precision of a measurement device is in part a function of its resolution which is the smallest graduation into which an instrument is divided .

For example a rule marked in 1/2 millimeters has a higher resolution and thus can be more precise than a rule marked in millimeters accuracy is defined as the degree to which an indicated value conforms to an acceptable standard value for example two tape measures may both have the same resolution or graduation in this case millimeters.

However if these tape measures are not equally accurate their differences become more noticeable at greater lengths each graduation on the stationery bar represents one millimeter the vernier plate essentially divides one millimeter into 50 units with each graduation representing two one hundredths of a millimeter these fifty units represent exactly the same distance as 49 units on the stationary bar because of this minut difference .

When a measurement is taken only one graduation on the plate will exactly coincide with a graduation on the stationary bar this intersection is where the fractional portion of a vernier caliper measurement is read to read the vernier caliper first indicate the number of millimeters that are between the zero on the stationary bar and the zero on the vernier plate then locate where the graduation on the vernier plate exactly.

Coincides with the graduation on the stationary bar and reading off of the vernier plate note that numbers value in hundredths of a millimeter and the vernier plate reading to the number of millimeters counted on the stationary bar for the final measurement micrometers are produced in various Precision's both in metric and English units in every case it is the thread pitch of the spindle screw that makes each type different.

the thread pitch is the distance between two adjacent thread crests in this example the thread pitch of the micrometer spindle screw is precisely 1/2 millimeter each revolution of the thimble moves the micrometer spindle 1/2 millimeter the micrometer has a reading line on the sleeve the vertical graduations on the top of the reading line each represent a single millimeter the vertical graduations below the reading line indicate half millimeters.

The beveled edge of the thimble is graduated into 50 divisions since a single revolution of the thimble moves the spindle 1/2 millimeter each thimble graduation equals one fiftieth of 1/2 millimeter or 1/100 of a millimeter the thimble is rotated and the spindle advanced until the feature is held between the anvil and the spindle face.

To read this micrometer add the number of millimeters and half millimeters visible on the sleeve to the number of hundredths of a millimeter indicated by the thimble graduation which coincides with the reading line on the micrometer sleeve