# Chapter-5| Comparator gauges

A device that compares the unknown length with the standard. Such measurement is known as comparison measurement and the instrument, which provides such a comparison, is known as Comparator.

Comparators are generally used for linear measurements. And it gives only dimensional differences in relation to a basic dimension of the object.
Various comparators currently available basically differ in their methods of amplifying and recording the variations measured.

The dial indicator or the dial gauge is one of the simplest and the most widely used Mechanical comparator.

Electronic gauges are more accurate and reliable than mechanical, which has made them the preferred choice in many applications.

In comparison measurement, it is dependent on the least count of the standard and the means for comparing. A comparator should have a high degree of accuracy and precision.

A comparator can be it mechanical, Pneumatic, or electrical, by the means of amplification of signals, the linearity of the scale within the measuring range should be assured.

## Types of Comparators

Comparators can be Mechanical or Electrical by the mean used for comparison

### 5.1 Dial Gauge (Plunger type & Lever type)

The dial indicator or the Plunger dial gauge is one of the simplest and the most widely used mechanical comparator.

First of all the use of plunger dial gauge used to compare work-pieces against a master.

Plunger Dial Gauge measurement limit is 10 mm with the least count of 0.01mm and 1mm with least count of 0.001 mm. likewise, another same comparator is Lever type.

It usually depends on the application, type of work, accuracy, and precision of work we like to measure.

Lever Dial Gauge also knew as Test Indicator. It used to measure sensitive contact.

Lever Dial gauge usually measure up to 0.80 mm. But some special type lever dial design for measurement up to 2 mm

### 5.2 Slip Gauge

Slip Gauge is set standard size rectangular shape block. Slip gauges are available in standard sets in both metric and inch units. In metric units, sets of 31, 48, 56, and 103 pieces are available.

For example, the set of 103 pieces consists of the following:

1. One piece of 1.005 mm
2. 49 pieces ranging from 1.01 to 1.49 mm in steps of 0.01 mm
3. 49 pieces ranging from 0.5 to 24.5 mm in steps of 0.5 mm
4. Four pieces ranging from 25 to 100 mm in steps of 25 mm

The cost of Slip Gauge is very high because of its Manufacturing deserve a high degree of accuracy and precision. Slip gauges should meet high standards of accuracy, flatness, parallelism, and surface quality.