Tap – Types (Taper, Second and Bottoming) and Care While Tapping in ITI Turner Trade

In the ITI Turner trade, threading is an important operation used to create internal threads in holes. This process is performed using a tool called a tap. Tapping ensures proper fitting of bolts and screws in mechanical components. This chapter explains the different types of taps and the precautions to be taken while tapping.

Introduction to Tap

A tap is a cutting tool used to produce internal threads inside a drilled hole. It has cutting edges and flutes that remove material and form threads.

Taps are used manually with a tap wrench or on machines such as drilling machines.

Material of Tap

Taps are made from high-speed steel (HSS) or alloy steel. These materials provide hardness, strength, and wear resistance required for cutting threads.

• High hardness for cutting edges
• Toughness to withstand torque
• Durability for long service life

Construction of Tap

A tap consists of the following parts:

• Shank: The top part held by the tap wrench
• Flutes: Grooves for chip removal
• Cutting Edges: Used for cutting threads
• Chamfer: The tapered portion at the tip

Types of Taps

Taps are mainly classified into three types based on the chamfer length:

1. Taper Tap

The taper tap has a long chamfer (8–10 threads). It is used for starting the threading process.

• Easy to align
• Gradual cutting action
• Used for initial threading

2. Second Tap (Intermediate Tap)

The second tap has a medium chamfer (3–5 threads). It is used after the taper tap to deepen the threads.

• Continues threading process
• Provides better thread formation

3. Bottoming Tap

The bottoming tap has a very short chamfer (1–2 threads). It is used to cut threads up to the bottom of a blind hole.

• Produces full threads
• Used for finishing work

Sequence of Tapping

The tapping process is usually done in the following sequence:

• First, use the taper tap
• Then, use the second tap
• Finally, use the bottoming tap

This sequence ensures accurate and smooth thread formation.

Uses of Tap

• Cutting internal threads
• Preparing holes for bolts and screws
• Repairing damaged threads

Advantages of Tapping

• Produces accurate threads
• Simple and effective process
• Suitable for different materials

Limitations

• Requires skill and care
• Risk of tap breakage
• Time-consuming for manual tapping

Care While Tapping

Proper care is necessary to ensure good quality threads and prevent damage to the tap:

• Select correct tap size for the hole
• Drill the hole to correct tapping size
• Use proper cutting fluid for lubrication
• Keep the tap aligned with the hole
• Apply uniform pressure
• Rotate the tap forward and slightly backward to break chips
• Avoid excessive force to prevent breakage

Safety Precautions

• Use proper tap wrench
• Wear safety goggles
• Do not use damaged taps
• Handle tools carefully

Maintenance of Tap

• Clean after use
• Store in proper place
• Apply oil to prevent rust
• Inspect regularly for wear

Application in Turner Workshop

In the Turner trade, taps are used for creating internal threads in workpieces such as nuts and machine parts. Proper tapping ensures correct fitting and smooth assembly.

Knowledge of different types of taps and correct tapping methods helps in achieving accurate results.

Conclusion

Tapping is an important operation in the ITI Turner trade. Understanding the different types of taps—taper, second, and bottoming—and their proper use is essential for producing accurate threads.

By following correct procedures and precautions, trainees can prevent tool damage and improve work quality.

In conclusion, proper knowledge and care while tapping ensure efficient and safe threading operations in the workshop.