Explanation: The dial indicator is attached to one of the moving machine components and its feeler rests against a specified point on the other moving part. The two parts are moved together by the same amount in the same direction and the variations in the reading are noted.

Explanation: Light weight dial indicator is used in this test. The direction of the measurement varies during rotation in relation to the gravity direction. The sensitivity of the apparatus to the gravity force is taken into account.

Explanation: If the distance between two lines is not small or large then the V-blocks are used. V- blocks are covered by a straight edge is used. Check for this is made by spirit level. For small distance there is no need of these.

Explanation: Permissible deviations or tolerance of parallelism of two plane surfaces or straight lines is 0.015 mm on 300 mm. Free end of the spindle relative to the table surface is in upward direction only.

Explanation: Two lines or axes are said in alignment or coincident when their distance apart at several points is measured over a specified length and this distance doesn’t exceed a specified value. The measured distance may be located either on the actual lines or on their prolongation.

Explanation: When plane passing through the axes is parallel to the reference plane then there is an equidistance. It is related to the distance between reference plane and the axes. It may be different axes, or the same axis.

Explanation: Two planes are parallel when the difference between the maximum and minimum dimension obtained that is maximum error over a given length does not exceed a specified value. The test is carried out in two directions which are perpendicular to each other.

Explanation: When a mandrel has represented the axis of rotation of spindle etc. It is not necessary that mandrel have been exactly centred and under such conditions the axis of the rotation of mandrel may describe a conical or hyperboloid.

Explanation: To test the parallelism, dial indicator can be used. The dial indicator is held on a support with base or flat base and is moved in one plane over a specified length, and the feeler is made to rest against the 2nd plane and the deviations are noted down.

Explanation: Parallelism can be defined as the tolerance which controls the parallelism between two features. It is possible to find the parallelism of the cylinder by measuring the two sides of a cylinder.