Hacksaw Blades – Sizes and Different Parts in ITI Turner Trade

In the ITI Turner trade, hacksaw blades are essential cutting tools used for cutting metals and other materials. The performance of a hacksaw largely depends on the type, size, and condition of the blade used. This chapter explains the sizes, construction, parts, and uses of hacksaw blades in detail.

Introduction to Hacksaw Blades

A hacksaw blade is a thin strip of steel with teeth on one edge, used for cutting materials. It is fitted into a hacksaw frame and operated manually by moving it back and forth.

Hacksaw blades are designed to provide efficient cutting and long service life.

Material Used for Hacksaw Blades

Hacksaw blades are made from high carbon steel or high-speed steel. Some blades are bi-metal, combining flexibility and hardness for better performance.

• High carbon steel for general use
• High-speed steel for durability
• Bi-metal blades for flexibility and strength

Sizes of Hacksaw Blades

Hacksaw blades are available in different sizes to suit various applications. The size is usually determined by the length of the blade.

• 250 mm (10 inches)
• 300 mm (12 inches)

The 300 mm blade is the most commonly used size in workshops.

Teeth Per Inch (TPI)

The number of teeth per inch (TPI) is an important factor in selecting a hacksaw blade:

• 14 TPI: For thick and soft materials
• 18 TPI: For medium thickness materials
• 24 TPI: For thin materials
• 32 TPI: For very thin sheets

Proper selection of TPI ensures smooth cutting and prevents damage to the blade.

Types of Hacksaw Blades

1. All Hard Blade

In this type, the entire blade is hardened. It is strong and suitable for heavy-duty cutting but may break if bent.

2. Flexible Blade

Only the teeth are hardened, while the back of the blade remains flexible. It is less likely to break and is widely used.

3. Bi-Metal Blade

Combines two metals for strength and flexibility. It has a long life and is suitable for industrial use.

Parts of Hacksaw Blade

A hacksaw blade consists of the following main parts:

• Teeth: Cutting edges that remove material
• Cutting Edge: The side where teeth are present
• Back Edge: Opposite side of the blade without teeth
• Body: The main flat portion of the blade
• Pin Holes: Holes at both ends for fixing the blade in the frame

Tooth Set

The teeth of the blade are slightly bent alternately to both sides. This is called the tooth set and helps in:

• Reducing friction
• Preventing the blade from sticking
• Producing a wider cut (kerf)

Direction of Teeth

The teeth of the hacksaw blade are generally pointed forward. Cutting takes place during the forward stroke, so pressure should be applied in that direction only.

Selection of Hacksaw Blade

Proper selection of blade depends on:

• Type of material
• Thickness of workpiece
• Required finish

Using the correct blade improves efficiency and reduces wear.

Uses of Hacksaw Blades

Hacksaw blades are used for:

• Cutting metal rods and bars
• Cutting pipes and tubes
• Cutting sheets and plates
• Trimming workpieces

Advantages of Hacksaw Blades

• Efficient cutting
• Available in different sizes and types
• Suitable for various materials
• Easy to replace

Limitations

• Wear out over time
• Can break if misused
• Limited to manual cutting speed

Precautions While Using Hacksaw Blades

• Ensure proper blade tension
• Use correct TPI for material
• Do not apply excessive force
• Replace damaged blades immediately

Maintenance of Hacksaw Blades

• Keep blades clean and dry
• Store properly to avoid damage
• Check teeth condition regularly

Application in Turner Workshop

In the Turner trade, hacksaw blades are used for cutting raw materials to required sizes before machining. They are also used for trimming and preparing workpieces.

Proper selection and use of hacksaw blades improve efficiency and reduce material wastage.

Conclusion

Hacksaw blades are essential tools in the ITI Turner trade. Understanding their sizes, types, and parts helps trainees perform cutting operations effectively.

By selecting the correct blade and following proper techniques, workers can achieve accurate and smooth cuts.

In conclusion, proper knowledge and care of hacksaw blades ensure better performance and longer tool life.