Sine Bar – Types and Uses & Slip Gauges – Types, Uses and Selection

In the ITI Turner trade, precise measurement of angles and dimensions is essential for accurate machining. Instruments such as the sine bar and slip gauges (gauge blocks) are widely used for high-precision measurements. This chapter explains the types and uses of sine bars, as well as the types, uses, and selection of slip gauges.

Sine Bar

Introduction

A sine bar is a precision instrument used to measure or set angles accurately using the sine principle. It is commonly used in conjunction with slip gauges.

Construction

• Made of hardened and ground steel
• Two precision cylinders (rollers) fixed at a known distance
• Flat upper surface for placing workpiece

Principle

The sine bar works on the trigonometric principle:

sin θ = Height (h) / Length (L)

Where L is the distance between the centers of the rollers.

Types of Sine Bar

1. Plain Sine Bar

Simple design with two rollers.

2. Sine Centre

Used for holding cylindrical workpieces.

3. Sine Table

Adjustable table used for angular setup.

4. Sine Vice

Combines sine bar with a vice for holding workpieces.

Uses of Sine Bar

• Measuring angles accurately
• Setting angles for machining
• Checking angular surfaces

Advantages

• High accuracy
• Simple construction
• Reliable measurement

Limitations

• Not suitable for large angles
• Requires slip gauges

Slip Gauges (Gauge Blocks)

Introduction

Slip gauges are precision measuring blocks used to obtain accurate dimensions. They are used with sine bars and other instruments for precise measurement.

Construction

• Made of hardened steel, carbide, or ceramic
• Highly polished surfaces
• Available in standard sizes

Types of Slip Gauges

1. Rectangular Slip Gauges

Most commonly used type.

2. Square Slip Gauges

Used for special applications.

3. Angular Slip Gauges

Used for measuring angles.

4. Wear Blocks

Used to protect gauge blocks from wear.

Uses of Slip Gauges

• Setting precise dimensions
• Measuring angles with sine bar
• Calibrating measuring instruments

Selection of Slip Gauges

Slip gauges are selected based on required dimension and combination of blocks.

• Choose minimum number of blocks
• Ensure proper wringing (joining)
• Use correct size combination

Wringing of Slip Gauges

Wringing is the process of joining slip gauges by sliding them together due to adhesion.

Advantages of Slip Gauges

• High precision
• Versatile use
• Standardized sizes

Precautions While Using

• Keep surfaces clean
• Handle carefully
• Avoid scratches
• Store properly

Maintenance

• Clean after use
• Apply protective oil
• Store in box

Application in Turner Workshop

In the Turner trade, sine bars and slip gauges are used for accurate angle measurement and setting. They help in producing precise components and maintaining quality standards.

They are essential tools in inspection and precision machining.

Importance

• Ensures accuracy
• Improves quality
• Reduces errors

Conclusion

Sine bars and slip gauges are important precision measuring tools in engineering. Understanding their types, uses, and selection helps in achieving accurate results.

Proper handling and maintenance ensure long life and reliability.

In conclusion, mastering these tools is essential for precision work in the ITI Turner trade.