The absolute length is computed with special slide rule provided for this purpose and in Zeiss interferometer corresponding linear measurement in microns is determined by special slide rule.

The gauging devices entering part should be spring loaded into ir proper position and not positively pushed. If excessive force is needed anywhere n furr operation is stopped to avoid damage.

Arrangement contains a dual collimator, white light source and slit which provides white light. A monochromatic light source, condenser and a slit which provide monochromatic light.

Screw ring gauges inspection by plug check gauges verifies that ring gauges lie between ir size limits. The major diameters are measured by inspection of thread form which provides an indirect verification.

The dial indicators of least count 0.01 mm can be calibrated by using passmeter or by micrometer dial comparator of least count 0.002 mm. The dial indicators can also be calibrated using slip gauges.

In micrometers, to cover entire range error in readings is checked by slip gauges. The maximum permissible error for class I micrometers is 0.004 mm and 0.008 mm for class II micrometers.

By using electronic techniques or electronic gauging systems speed of gauging increased. The electrical impulse produced in electronic gauging system is generally displayed by an indicating instrument.

Self-diagnostic systems are used in automatic inspection machines and se systems allow easy and fast identification of circuits which are faulty, reducing downtime and improving maintenance efficiency.

Profile gauges are most conveniently inspected by optical projection at a standard magnification. The standard magnification mostly used is 50. Anor standard magnification which can be used is 100 but it is generally not used due to reduced intensity of illumination at projector screen, it is generally not greater than 50.

A special control shaft is used to check this where a right angled blade is provided at right angle to shaft diameter line. The ocular line is made to coincide with blade and column is titled, shift in position of ocular line is noted, this shift is required error.