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Combination Set – Square Head, Center Head and Protractor Head – Construction, Function and Uses

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By iti | 3:17 PM IST, Sat March 21, 2026

Combination Set – Square Head, Center Head and Protractor Head – Construction, Function and Uses

In the ITI Turner trade, accurate measurement and marking are essential for producing high-quality components. The combination set is a versatile measuring and marking tool used in engineering workshops. It consists of different heads such as the square head, center head, and protractor head. This chapter explains their construction, functions, and uses in detail.

Introduction to Combination Set

A combination set is a precision tool consisting of a steel rule and interchangeable heads. It is used for measuring, marking, and checking angles and dimensions.

The main parts include:

  • Steel rule
  • Square head
  • Center head
  • Protractor head

Square Head

Construction

  • Made of cast iron or steel
  • Fixed at 90° and 45° angles
  • Includes spirit level and scriber
  • Adjustable along the rule

Function

  • Checking right angles (90°)
  • Checking 45° angles
  • Measuring depth and height

Uses

  • Marking perpendicular lines
  • Checking squareness of surfaces
  • Layout work

Center Head

Construction

  • V-shaped head
  • Fits on the steel rule
  • Made of hardened steel

Function

  • Locates the center of cylindrical objects

Uses

  • Marking center lines on shafts
  • Finding center of round bars

Protractor Head

Construction

  • Graduated circular scale
  • Adjustable blade
  • Locking mechanism

Function

  • Measuring angles
  • Setting required angles

Uses

  • Checking angular surfaces
  • Marking angles

Advantages of Combination Set

  • Versatile tool
  • High accuracy
  • Multiple functions in one instrument

Precautions

  • Handle carefully
  • Keep clean
  • Avoid dropping

Maintenance

  • Store in protective case
  • Clean after use
  • Apply light oil

Application in Turner Workshop

In the Turner trade, combination sets are used for marking, measuring, and checking angles and dimensions. They help in ensuring accuracy and quality in machining operations.

The square head is used for right angles, the center head for locating centers, and the protractor head for angle measurement.

Importance

  • Improves accuracy
  • Reduces errors
  • Enhances productivity

Conclusion

The combination set is an essential tool in the ITI Turner trade. Its different heads provide multiple functions such as measuring angles, marking centers, and checking squareness.

Understanding its construction and uses helps trainees perform accurate measurement and layout work.

In conclusion, mastering the use of combination set is important for achieving precision and quality in engineering work.

Book traversal links for Combination Set – Square Head, Center Head and Protractor Head – Construction, Function and Uses

  • ‹ Combination Drill – Appropriate Selection of Size from Chart in ITI Turner Trade
  • Up
  • Conventional Thread Charts, Gear Ratio Calculations and Screw Thread Micrometer ›

Book navigation

  • Application of Each Type of Thread and Drive Train in Lathe
  • Back Gear Unit – Its Construction and Use in ITI Turner Trade
  • Basic Process of Soldering, Welding and Brazing
  • Bevel Protractor & Vernier Bevel Protractor – Function and Reading
  • Buttress thread cutting (male & female) & tool grinding
  • Calculation Involving Pitch Related to ISO Thread Profile
  • Calculation Involving Tool Thickness, Core Diameter, Pitch Proportion and Depth of Cut of Square Thread
  • Calculation involved to find Out drill size (Metric and Inch)
  • Calculation of Acme Thread and Buttress Thread – Depth, Core Diameter, Pitch Proportion and Uses
  • Calculation of Core Diameter, Gear Train (Simple Gearing) and Thread Cutting Calculations
  • Calculation of Gear Ratios for Metric Thread Cutting on Inch Lead Screw Lathe and Vice-Versa
  • Calipers – Types and Uses (Firm Joint) in ITI Turner Trade
  • Center Punch – Materials, Construction and Uses in ITI Turner Trade
  • Classification of Lathe and Function and Construction of Different Parts of Lathe
  • Combination Drill – Appropriate Selection of Size from Chart in ITI Turner Trade
  • Combination Set – Square Head, Center Head and Protractor Head – Construction, Function and Uses
  • Conventional Thread Charts, Gear Ratio Calculations and Screw Thread Micrometer
  • Cutting Speed, Feed, Depth of Cut and Calculations (Speed, Feed, RPM) for Different Materials
  • Cutting speed, feed depth of cut, calculation involved-speed feed R.P.M. etc. recommended for different materials
  • Definition of Machine & Machine Tool and Its Classification in ITI Turner Trade
  • Dial Test Indicator for Parallelism & Concentricity and Grinding Wheel – Abrasive, Grit, Grade, Bond
  • Dies – Different Types and Uses in ITI Turner Trade
  • Different Methods of Forming Threads
  • Different Types of Micrometer and Outside Micrometer
  • Different Types of Screw Threads – Their Forms and Elements
  • Different lathe accessories, their use and care
  • Digital Vernier Caliper in ITI Turner Trade
  • Drill Chuck – Its Uses in ITI Turner Trade
  • Drill Machine – Different Parts in ITI Turner Trade
  • Drills – Parts, Types, Sizes, Cutting Angles, Cutting Speed, Boring Tool, Countersinking and Counterboring
  • Driving Plate in Lathe Machine
  • Face Plate, Fixed Steady and Travelling Steady – Construction and Uses
  • Fundamentals of Thread Cutting on Lathe
  • Getting to Know the Lathe with its Main Components, Lever Positions and Lubrication Points
  • Hacksaw Blades – Sizes and Different Parts in ITI Turner Trade
  • Hacksaw blades-sizes, different pitch for different materials
  • Hacksaw – Types and Uses in ITI Turner Trade
  • Hammer and Chisel – Materials, Types and Uses in ITI Turner Trade
  • Headstock – Cone Pulley Type, All Geared Type, Construction, Function and Tumbler Gear Set
  • Health, Safety and Environment Guidelines, Legislations & Regulations in ITI Turner Trade
  • History and Gradual Development of Lathe in ITI Turner Trade
  • Hole Basis & Shaft Basis System and Representation of Tolerance in Drawing
  • Knurling – Meaning, Necessity, Types, Grade and Cutting Speed
  • Lathe Accessories – Chucks (Independent, Self-Centering, Collet, Magnetic, etc.) – Construction, Function and Uses
  • Lathe Centers – Types and Uses & Lathe Carrier (Dog) – Function, Types and Uses
  • Lathe Cutting Tool – Types, Shapes, Angles and Specification in ITI Turner Trade
  • Lathe Mandrel, Interchangeability, Limits, Fits and Tolerances (BIS: 919)
  • Lubricant and Coolant – Types, Necessity, Distribution System, Selection, Handling and Care
  • Lubricant – Function, Types and Sources of Lubricants
  • Magnetic Stand Dial Indicator – Uses and Care
  • Mandrel – Different Types and Its Uses
  • Measurement, Line Standard and End Standard, Steel Rule – Types, Graduation and Limitations
  • Method of Taper Angle Measurement
  • Method of lubrication
  • Nomenclature of Drill in ITI Turner Trade
  • Prick Punch and Scriber in ITI Turner Trade
  • Reamers – Types and Uses in ITI Turner Trade
  • Reducing Speed – Necessity and Uses in ITI Turner Trade
  • Sine Bar – Types and Uses & Slip Gauges – Types, Uses and Selection
  • Sources of Error with Micrometer and How to Avoid Them
  • Surface Plate – Its Necessity and Use in ITI Turner Trade
  • Tap - different types (Taper 2nd and bottoming) care while tapping
  • Taper – Methods of Expressing Taper, Standard Tapers and Taper Turning Methods
  • Thread Chasing Dial – Function, Construction and Use
  • Tool Life and Negative Top Rake – Application and Performance Compared to Positive Top Rake
  • Transfer Caliper – Construction and Uses
  • Try Square – Types, Parts, Materials and Uses in ITI Turner Trade
  • Tumbler Gear Set in Lathe Machine
  • Types of Lathe Drivers, Merits and Demerits in ITI Turner Trade
  • Use of Digital Measuring Instruments in ITI Turner Trade
  • Vee Block, Scribing Block and Straight Edge – Types and Uses in ITI Turner Trade
  • Vernier Caliper – Construction, Principle, Graduation, Reading and Least Count
  • Vernier Height Gauge, Templates and Screw Thread – Definition, Purpose and Elements
  • Vernier Scale – Graduation and Reading

Books

Occupational Safety & Health in ITI Turner Trade
Importance of housekeeping & good shop floor practices

Article

Hacksaw – Parts, Types and Uses in Workshop Practice
Bench Vice – Parts, Functions and Uses in Workshop
5S Methodology – Workplace Organization and Industrial Efficiency
क्या आईटीआई टर्नर ट्रेड करने के बाद मैं अपना खुद का व्यवसाय शुरू कर सकता हूँ?
Can I Start My Own Business After Doing ITI in Turner Trade?
आईटीआई टर्नर करने के बाद सरकारी नौकरी में क्या अवसर हैं?
What is the Scope in Government Job after Doing ITI in Turner?
आईटीआई टर्नर ट्रेड करने के लाभ
Benefits of Doing ITI in Turner Trade

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