Thread Chasing Dial – Function, Construction and Use

In the ITI Turner trade, thread cutting on a lathe requires precise synchronization between the movement of the cutting tool and the rotation of the workpiece. To maintain this synchronization and ensure accurate threading, a device called the thread chasing dial (or thread dial indicator) is used. This chapter explains its construction, function, working, and uses in detail.

Introduction to Thread Chasing Dial

A thread chasing dial is a device fitted on the carriage of a lathe machine. It helps the operator to engage the half-nut lever at the correct time during thread cutting, ensuring proper alignment of successive cuts.

Construction of Thread Chasing Dial

The thread chasing dial consists of the following main parts:

• Dial Body: Circular housing that contains the mechanism
• Graduated Dial: Marked with numbers or lines
• Worm Gear: Engages with the lead screw
• Pointer: Indicates the position on the dial
• Mounting Bracket: Fixes the dial to the carriage

The worm gear rotates as the lead screw rotates, causing the dial to move.

Function of Thread Chasing Dial

• Indicates the correct position to engage half-nut
• Maintains synchronization during threading
• Prevents damage to threads

Working Principle

The thread chasing dial works on the principle of gear rotation. The worm gear meshes with the lead screw, and as the lead screw rotates, the dial rotates accordingly.

The dial markings indicate specific positions where the half-nut can be engaged safely without disturbing the thread pitch.

Use of Thread Chasing Dial

Steps for Operation

• Set up the lathe for thread cutting
• Start the machine
• Observe the rotating dial
• Engage half-nut when the pointer aligns with a specific mark
• Repeat the process for successive cuts

Importance in Thread Cutting

• Ensures accurate thread pitch
• Maintains alignment of threads
• Reduces chances of error

Advantages

• Easy to operate
• Improves accuracy
• Saves time

Limitations

• Not suitable for all thread pitches
• Requires proper understanding of dial markings

Precautions While Using

• Engage half-nut only at correct marking
• Do not force engagement
• Check gear alignment

Maintenance

• Keep clean and free from dirt
• Lubricate moving parts
• Check for wear

Application in Turner Workshop

In the Turner trade, the thread chasing dial is widely used during thread cutting operations. It helps operators maintain synchronization and achieve accurate threads.

It is especially useful for repeated threading operations.

Importance in Machining

• Improves thread quality
• Reduces rejection of parts
• Enhances efficiency

Conclusion

The thread chasing dial is an important accessory in lathe machines used for accurate thread cutting. It helps in maintaining synchronization and ensuring proper thread formation.

Understanding its construction and use is essential for performing threading operations efficiently.

In conclusion, proper use of the thread chasing dial ensures precision and quality in the ITI Turner trade.