Vernier Caliper vs Screw Gauge
Vernier calipers and screw gauges are devices that are used in measurements. A vernier caliper is a device which consists of a ruler and a vernier scale attached to it. A screw gauge, also known as a micrometer screw gauge, is a device which consists of a screw measuring system. These devices are widely used in fields such as physics, engineering, woodworking, metalworking, medicine and various other fields. In this article, we are going to discuss what micrometer screw gauges and vernier calipers are, the operating principles of micrometer screw gauge and the vernier caliper, the applications of vernier caliper and micrometer screw gauge, the similarities between these two, and finally the difference between micrometer screw gauge and vernier caliper.
Vernier Caliper
The vernier caliper is a measuring device that consists of a main scale and a vernier scale, which is attached to the main scale but movable throughout the length of the main scale. The vernier caliper measures the separation between the jaws of the vernier caliper. There are inner jaws, which are used to measure internal radii or distances, and outer jaws, which are used to measure outer radii and outer distances. The main scale has separations of either 0.1 cm or 0.05 cm. A number of these separations are divided to a different number of separations inside the vernier scale. The most common of these is the 9 units of the main scale of 0.1 divided into 10 units inside the vernier caliper. When the jaws touch each other, the 0 of the vernier scale and the 0.0 of the main scale coincide. When the jaws are moved apart so that the 1 of the vernier scale coincides with the 0.1 of the main scale, the jaws are moved apart by a distance of 0.01 cm, which is 1/10th of the smallest reading of the main scale.
The general formula for measurements in vernier caliper is,
The smallest measurement of a vernier caliper = (value of the smallest reading in main scale – the size of a separation in the vernier scale) * The value of the smallest reading in main scale
Micrometer Screw Gauge
The micrometer screw gauge, also known as the micrometer or the screw gauge, is a measuring instrument that is used when measuring small diameters. The basic principle of the micrometer screw gauge is that the distance a screw travels when the screw is turned by 1 complete circle is equal to the gap between two screw threads of the gauge. The screw head attached to the screw has a scale going around the circumference of the screw head. If the circumference scale is divided into n parts and the thread gap is d mm, the smallest reading of the micrometer screw gauge is d/m mm. In a typical screw gauge, the screw gap is 0.5 mm, and the scale is divided into 50 parts, which makes the smallest reading 1/100 mm. Some micrometers have vernier scales coupled to the circumference of the main body to get the smallest reading of 1 micrometer.
Vernier vs Micrometer
- A screw gauge is capable of measuring a difference as small as 0.01 mm in general cases. The vernier caliper only has the ability to measure differences as small as 0.05 in the extreme cases.
- A single vernier caliper can measure inner lengths, outer lengths and depths without any change, but a micrometer screw gauge can only measure one type at a time.