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Screw Gauge
A screw gauge, also known as a micrometre screw gauge, is a precision measuring instrument used to accurately measure the dimensions of small objects with high precision. It is commonly used in various fields such as engineering, manufacturing, and scientific research where precise measurements are crucial.
Screw Gauge — Important Terms
- Main Scale: The main scale is a linear scale on the sleeve of the screw gauge. It measures whole units of the measurement.
- Circular Scale (Thimble Scale): The circular scale on the thimble provides fractional measurements. Turning the thimble aligns it with the main scale for accurate readings.
- Frame: The primary structure of the screw gauge that holds all components together. Typically designed in a C-shape, it houses both a fixed anvil and a movable spindle.
- Thimble: The outer rotating component of the screw gauge, marked with a measurement scale. By turning the thimble, pressure is applied to the object being measured.
- Sleeve: The cylindrical section that accommodates the thimble and is attached to the frame. Some sleeves have a linear scale alongside the thimble scale to aid in measurement.
- Anvil: The stationary reference surface positioned against the object to be measured. It’s located at the lower end of the frame.
- Spindle: The mobile part that advances or retreats as the thimble is rotated. This part makes contact with the object being measured and transfers linear motion via the screw mechanism.
- Ratchet: A feature preventing excessive pressure during measurement. This ensures consistency and reproducibility in readings.
FAQs About Screw Gauge
Can a screw gauge be used to measure internal diameter?
Answer: No
What is the least count of micrometres?
Answer: The least count of micrometres is 0.01mm.
What is pitch in a screw gauge?
Answer: It is the distance travelled by the measuring spindle (or thimble) for each complete rotation of the screw.
Why is thickness measured multiple times?
Answer: Multiple measurements enhance accuracy by reducing errors and providing a more reliable average value.
How does zero error affect screw gauge measurements?
Answer: Zero error in a screw gauge causes a consistent deviation, leading to inaccurate results.