The Vernier Caliper

The Vernier Caliper

Definition

• An instrument for making accurate linear measurements.

• Introduced in 1631 by Pierre Vernier.

Main Features

• Utilizes two scales:

  • Main Scale: Similar to a ruler.

  • Vernier Scale: Graduated auxiliary scale that slides parallel to the main scale for precise readings.

• Commonly used in laboratories and manufacturing for quality control.

Parts of the Vernier Caliper

Lower Jaws

• Main feature of the caliper, designed to grip objects for measurement.

• One jaw is fixed; the other moves; measures outer dimensions (length, width, diameter).

Upper Jaws

• Smaller jaws for measuring inside dimensions of hollow objects (e.g., pipes, boxes).

• Operate by opening until touching the inner edges of the object.

Depth Rod

• Used to measure the depth of holes or steps.

Main Scale

• Large scale along the caliper body, graduated in centimeters, millimeters, or inches.

• It is stationary.

Thumb Screw

• Located at the bottom of the vernier scale.

• Allows user to slide jaws and depth rod while maintaining grip on the object.

Lock Screw

• Fixes the position of jaws after placement for stable readings.

Measurement Techniques with Vernier Caliper

1. Outside Measurement

• Measures the outer surface of an object.

• Open lower jaws, close around the object, and read measurement.

• Ensure caliper is perpendicular and free of dirt.

2. Inside Measurement

• Uses upper jaws to measure dimensions of a hole.

• Close jaws, place inside the space, and open until touching inside edges; read measurement.

3. Depth Measurement

• Determines depth using the depth rod.

• Place caliper at the hole's top and extend the rod until it touches the bottom; read measurement.

4. Step Measurement

• Measures depth or height differences in a workpiece.

• Place sliding jaw on upper step, open caliper until fixed jaw touches lower step; read measurement.