GROUP MEMBERS

TAHIR TARIQ (2010-ME-409)

AHSAAN MUSTAFA (2010-ME-451)

Comparator

Comparators are the instruments,

that are used to find out unknown size with known reference

Designed in a such a way that a small movement at measuring end

is converted into large movement in reading end

Which means comparators are used to measure a small difference

in sizes by comparing them

Types of Comparator

Mechanical Comparator

Electrical Comparator

Pneumatic Comparator

High Magnification gauge Comparator

Fluid displacement Comparator

High Magnification Gauge

Comparator

There are two types of HMGC

Brook’s Level Comparator

Eden Rolt Comparator

Important note

It should be noted that all type of comparators are comparing

instruments.

They are not Measuring Instruments it means there are only used for

comprising of a unknown size with the Known reference size.

Our Topic

We are bound to discuss the Following comparator

Eden Rolt Comparator

Principle

It works on two main principle

Mechanical Magnification ( By lever Mechanism )

Optical Magnification ( Optical Shadow Mechanism)

Components of ER Comparator

Anvil ( Both Movable and Non-Movable)

Block ( Both Moving and Non-Moving )

Steel Strips

Pointer Strips

Pointer Arm

And rest are explained in the figure Shown

Function of Component

Anvil Purpose of Fixed Anvil is to provide the grip for our work-part

Movable anvil is used to play a part in providing Mechanical Magnification

Strips The strips are used to provide displacement and cause of deflection

of Pointer Arm.

Block Causes twisting of a lever.

Optical Shadow Mechanism

(Component)

Lamp

Prism

Spider web

Lens

Mirror

Scale

How it Works

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Mechanical Mechanism

Twisting Effect

Optical Shadow Projection

Specification

Each division of its scale represents 0.0002 mm so that by estimation

it is possible to read 0.00002 mm.

This comparator is capable of calibrating gauges up to 25 mm.

Mechanical Magnification can be with in the range of 300-400x(with lever about 200mm)

Optical Magnification can be 60x

So the total Magnification can be obtained by this comparator is 20,000x

Manufacturing ease…………..

The space between strips and length of lever and rest of accuracy

are not required to be much Precise.

Because

That can be compensated by the facility of calibration.

Example

Gauge block (known size)..

Method of Calibration

Place Gauge of known size

Marks it reading as a reference( ‘0’ )

Remove Gauge

Place another unknown size gauge

Check out the reading

If the scale gives value beyond the ‘0’ then add value to reference

If a scale gives reading before ‘0’ then we subtract from reference.