Screw Gauge | Micrometer

What is a Screw Gauge?

A screw gauge is a precision instrument used to measure the thickness or diameter of small objects. It is a type of micrometer that uses a screw to move a plunger against the object being measured. The screw has a calibrated scale that allows the user to read the measurement in millimeters or inches.

Screw gauges are used in a variety of industries, including manufacturing, engineering, and machining. They are used to measure the thickness of sheet metal, the diameter of wires, and the clearance between machined parts.

Least Count of Screw Gauge

The least count of a screw gauge is the smallest measurement that can be made with the instrument. It is determined by the pitch of the screw and the number of divisions on the thimble.

The pitch of the screw is the distance that the screw moves when it is turned one complete revolution. The number of divisions on the thimble is the number of small divisions on the thimble that are equal to one pitch.

The least count of the screw gauge is calculated by dividing the pitch of the screw by the number of divisions on the thimble.

The formula for the least count of a screw gauge is:

Least count = Pitch / Number of divisions on the thimble

For example, if a screw gauge has a pitch of 0.01 mm and a thimble with 50 divisions, then the least count of the screw gauge is:

Least count = 0.01 mm / 50 = 0.0002 mm

In other words, the smallest measurement that can be made with this screw gauge is 0.0002 mm.