Precision instruments are vital for accurate measurement and inspection in machining and manufacturing. These tools ensure that components meet specified dimensions and tolerances. This section covers the usage of dial gauges, height gauges, sine bars, and slip gauges, and provides insight into measurement and inspection techniques using these precision instruments.

 Usage of Dial Gauges, Height Gauges, Sine Bars, and Slip Gauges

1. Dial Gauges:

   Dial gauges, also known as dial indicators, measure small linear distances and deviations. They are used for precision measurement of dimensions, run-out, and alignment.

  Components:

    Dial: Displays the measurement readings. It has a needle or pointer that moves over a graduated scale.

    Plunger: Moves in and out to make contact with the surface being measured. It converts the mechanical movement into a dial reading.

    Housing: The outer casing that contains the dial and plunger mechanism.

  Applications:

    Measuring Run-Out: Checking the accuracy of rotating components by measuring deviations from the true circular path.

    Checking Alignment: Verifying the alignment of machine components and parts.

  Examples:

    Checking Shaft Run-Out: Use a dial gauge to measure the run-out of a rotating shaft to ensure it is within acceptable limits.

    Measuring Surface Flatness: Place a dial gauge on a surface plate to measure the flatness of a workpiece.

2. Height Gauges:

   Height gauges are used to measure the height of a workpiece from a reference surface. They are commonly used for marking, measuring, and comparing heights in precision work.

  Components:

    Vertical Column: The main body of the height gauge that holds the measuring scale.

    Measuring Probe: The part that contacts the workpiece. It can be a dial indicator, digital readout, or other measuring devices.

    Base: The bottom part that sits on the reference surface and provides stability.

  Applications:

    Measuring Component Heights: Accurate measurement of the height of a workpiece from a reference surface.

    Marking Operations: Marking precise heights or features on a workpiece for further machining or inspection.

  Examples:

    Measuring the Height of a Workpiece: Use a height gauge to measure the height of a machined part relative to a surface plate.

    Marking Drill Points: Use a height gauge to mark precise drill points on a component.

3. Sine Bars:

   Sine bars are precision tools used to measure angles and check the accuracy of components. They are commonly used in conjunction with sine plates for angle measurement.

  Components:

    Bar: A precision-ground bar with two cylindrical rollers at its ends.

    Angle Setting: The height of the sine bar is adjusted to achieve the desired angle.

  Applications:

    Angle Measurement: Determining the angle of a workpiece by setting the sine bar at a specific height.

    Checking Angular Accuracy: Verifying the accuracy of angles in machined components.

  Examples:

    Measuring an Angle: Use a sine bar to measure the angle of a bevelled edge on a metal plate.

    Checking the Angle of a Machined Part: Verify the angle of a machined component using a sine bar and a sine plate.

4. Slip Gauges:

   Slip gauges, or gauge blocks, are precision tools used to measure and set exact lengths. They are often used for calibration and to ensure the accuracy of measuring equipment.

  Components:

    Gage Blocks: Rectangular blocks made from high-quality steel, ceramic, or carbide. They come in various thicknesses.

    Clamping Device: A tool to hold and stack the gauge blocks together to achieve the desired length.

  Applications:

    Setting Measurements: Used to set and verify the accuracy of measuring instruments and tools.

    Calibrating Equipment: Ensuring that measuring equipment is calibrated to accurate standards.

  Examples:

    Setting a Micrometer: Use slip gauges to set and calibrate a micrometer to ensure precise measurements.

    Checking Tool Lengths: Verify the length of cutting tools or other components using slip gauges.

 Measurement and Inspection Techniques Using Precision Instruments

1. Using Dial Gauges:

  Setup: Mount the dial gauge on a stable surface or use a stand. Ensure that the plunger makes contact with the surface being measured.

  Measurement: Rotate the component or move the gauge to measure deviations. Read the dial to determine the magnitude of run-out or surface irregularities.

  Inspection: Compare measurements to specified tolerances to determine if the component is within acceptable limits.

2. Using Height Gauges:

  Setup: Place the height gauge on a surface plate or reference surface. Ensure the base is stable and the measuring probe is aligned with the workpiece.

  Measurement: Adjust the height gauge to measure the height of different points on the workpiece. Read the measurement on the dial or digital display.

  Inspection: Verify that the height measurements meet design specifications or tolerances.

3. Using Sine Bars:

  Setup: Place the sine bar on a flat surface, such as a sine plate. Adjust the height of the sine bar to achieve the desired angle.

  Measurement: Position the workpiece on the sine bar and measure the angle using a protractor or other angular measuring tool.

  Inspection: Compare the measured angle to the specified angle to ensure accuracy.

4. Using Slip Gauges:

  Setup: Clean the gauge blocks and stack them to achieve the desired length. Use a clamping device to hold the blocks together.

  Measurement: Use the stacked gauge blocks to measure or set the length of tools or components. Verify the length with precision instruments.

  Inspection: Ensure that the length of the component or tool matches the specifications or tolerances.