LINEAR MEASURING INSTRUMENTS
*The linear measurements includes the measurement of lengths, diameters, heights and thickness.
*The basic principle of the linear measurement is that of comparison with standard dimensions on a suitably engraved instrument (or) Device.
*The various devices used for measuring the linear measurements are
i) Vernier Caliper
ii) Micrometer
iii) Slip gauge
iv) Comparators
1. Vernier Caliper
*Vernier calipers have two scales namely, the main scale and vernier scale. The vernier scale moves along the main scale.
*Verniers are used to measure both internal and external dimensions.
Type A vernier Caliper
Type B Vernier Caliper
Type C Vernier Caliper
vernier Height Gauge
Vernier Depth Gauge
2. Micrometer
*A gauge which measures small distances (or) thicknesses between its two faces, one of which can be moved away from (or) towards the other by turning a screw with a fine thread.
*The micrometer has an accurate screw consisting of 10 to 20 threads per cm. This screw rotates inside a fixed nut.
*The end of the screw as the measuring tip and fixed anvil acts other measuring tip.
Outside Micrometer
Inside Micrometer
Digital Micrometer
Blade Type Micrometer
Thread Micrometer
3.SLIP GAUGE
*Slip gauges are used as measuring blocks. It is also called as precision gauge blocks.
*They are made of hardened alloy steel of rectangular cross-section.
*Different sets of slip gauges are manufactured in standard sets of 32 pieces, 45 pieces, 88 pieces, etc.,
4. COMPARATORS
*Comparators are one form of linear measurements device which is quick and more convenient for checking the large number of identical dimensions.
*It cannot be used as an absolute measuring device but can only compare two dimensions.
*The common types are
i) Mechanical Comparators
ii) Electrical Comparators
iii) Optical Comparators
iv) Pneumatic Comparators
v) Fluid Displacement Comparators
vi) Magnitude Comparators
