Screw Gauge Important Questions

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Very Short Answers Questions [1 Mark Questions]

Ques. What is the least count of a screw gauge?

1. 0.1 mm
2. 0.01 mm
3. 0.2 mm
4. 0.02 mm

Ans. The correct answer is b. 0.01 mm

Explanation: The least count of a screw gauge is 0.01 mm. It can be calculated as the ratio of the pitch to the number of divisions on a circular scale.

Ques. Which of the following is incorrect about a screw gauge?

1. The graduated surface diameter of the barrel should be 5 mm
2. The thimble and barrel should have a dull finish
3. The screw has 10 or 20 threads per cm
4. The total travel of the measuring spindle is called the measuring range

Ans. The correct answer is a. The graduated surface diameter of the barrel should be 5 mm

Explanation: Thimble and barrel should be dull for easier reading. The graduated surface diameter of the barrel should not be less than 10 mm.

Ques. What is the total error in a screw gauge?

1. Error in parallelism
2. Positive and negative deviation from the zero point
3. Maximum difference between ordinates of cumulative error
4. Deviation from measurement of a nominal dimension

Ans. The correct answer is c. Maximum difference between ordinates of cumulative error

Explanation: The deviation of measurement from a nominal dimension is referred to as cumulative error. It contains errors such as thread errors, face measurement errors, and so on. The total error is the maximum difference between the ordinates of cumulative error.

Ques. What is the use of a ratchet stop in a screw gauge?

1. Forms measuring tip
2. Prevent motion of the spindle
3. Provide measuring surface
4. Maintain uniform measuring pressure

Ans. The correct answer is d. Maintain uniform measuring pressure

Explanation: To maintain a uniform measurement pressure, a ratchet stop is provided at the end of the thimble cap. By ratchet stop standard conditions of measurement are attained.

Ques. The spindle cannot be moved if the thimble is locked.

1. True
2. False

Ans. The correct answer is b. False

Explanation: Even if the thimble is locked, the spindle can be moved to obtain a precise measurement.

Ques. The C-shaped body that holds the anvil and barrel in a screw gauge is known as

1. Spindle
2. Sleeve
3. Frame
4. Anvil

Ans. The correct answer is c. Frame

Explanation: The screw gauge frame is C-shaped, thick, and thick.

Ques. Are micrometers used in telescopes or microscopes?

1. Yes
2. No

Ans. The correct answer is a. Yes

Explanation: Micrometers are used to calculate the diameter of celestial bodies or small objects in microscopes or telescopes.

Ques. Which type of micrometer features a three-anvil head on a micrometer base and is used to measure inside diameters?

1. Bench micrometers
2. Bore micrometers
3. Universal micrometer sets
4. Blade micrometers

Ans. The correct answer is b. Bore micrometers

Explanation: Bore micrometers are specifically designed to measure inside diameters of holes and bores. They feature a three-anvil head that allows them to reach into confined spaces.

Ques. Pitch is given by the formula

1. The pitch of the screw gauge = (distance moved by a screw)/(no. of rotations given)
2. The pitch of the screw gauge = (no. of rotations given)/(distance moved by a screw)
3. The pitch of the screw gauge = (distance moved by a screw) - (no. of rotations given)
4. The pitch of the screw gauge = (no. of rotations given) - (distance moved by a screw)

Ans. The correct answer is a. The pitch of the screw gauge = (distance moved by a screw)/(no. of rotations given)

Explanation: The formula of the pitch of the screw gauge is given by the ratio of distance moves by a screw to the number of rotations given.

Ques. What is the hardness of measuring the faces of the anvil and spindle?

1. 1000 HV
2. 600 HV
3. 100 HV
4. 800 HV

Ans. The correct answer is d. 800 HV

Explanation: The hardness of the anvil and spindle measuring faces is about 800 HV 

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Short Answers Questions [2 Marks Questions]

Ques. What is a screw gauge?

Ans. A screw gauge is a mechanical instrument that measures the diameter, radius, or thickness of a thin wire or metal sheet precisely. It is also known as a micrometer screw gauge.

Ques. Name five stationary parts of the screw gauge.

Ans. Some of the stationary parts of the screw gauge are 

• Sleeve
• Anvil
• Spindle
• Frame
• Thimble

Ques. What are the different types of screw gauges?

Ans. Some different types of screw gauges are

• Universal micrometer sets
• Ball micrometers
• Tube micrometers
• Bench micrometers
• Blade micrometers

Ques. Define the least count of a screw gauge.

Ans. The distance moved by the tip of the screw when turned through one division of the head scale is referred to as the least count of screw gauge.

\(Least count of screw gauge = \frac{Pitch}{Total number of divisions on circular scale}\)

Ques. What is the pitch of a screw gauge?

Ans. The distance moved by the spindle during each rotation is known as the pitch of the screw gauge. This is determined by moving the head scale of the device over the pitch scale to complete one full rotation.

Ques. What is a universal micrometer set?

Ans. Universal micrometer sets include a variety of interchangeable anvils, such as flat, spherical, spline, disk, blade, point, and knife-edge. The term universal micrometer may also refer to a type of micrometer with a modular frame that allows one micrometer to operate as an outside mic, depth mic, step mic, and so on.

Ques. What is the zero error of a screw gauge?

Ans. The zero error of a screw gauge occurs when the zero line on the circular scale does not correspond with zero on the linear scale when the screw on the circular scale is fully tightened or adjusted.

Ques. What are various types of motion possessed by the screw in the screw gauge?

Ans. The different types of motion possessed by the screw in the screw gauge are

The linear motion is possessed by the axis.

The circular motion possessed by the surface

Ques. What is the backlash error in the screw gauge?

Ans. Backlash error occurs in a screw gauge when the direction of rotation is suddenly changed. The screw may continue to rotate, but the screw itself will not move forward or backward. As a result, the scale reading may change even though the screw has not moved.

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Long Answers Questions [3 Marks Questions]

Ques. What are the disadvantages of a screw gauge?

Ans. The following are the disadvantages of a screw gauge

Limited range: The majority of screw gauges have a limited measuring range of only 25mm (metric) and 1″ (imperial). Consequently, for objects exceeding these dimensions, additional screw gauges are necessary.

Larger screw gauges can be expensive: Due to their size, screw gauges designed for larger measurements are significantly more costly than smaller screw gauges.

Different types are required for different measuring tasks: Unlike dial calipers or vernier calipers that can handle various measurements (outside, inside, step, and depth), screw gauges are limited to performing a single measuring task. For example, if you needed to measure the diameter of a hole in a piece of wood as well as the outside width of that wood, you would require both an inside screw gauge and an outside screw gauge.

Ques. What are the applications of a screw gauge?

Ans. The following are the applications of a screw gauge

Screw gauge can be used to measure the diameter of round objects, mainly wires, with an accuracy of 0.001cm.

The radius of wires and other circular objects can be determined with a screw gauge.

A screw gauge can also be used to determine paper thickness.

The thickness of metal sheets and glass slabs can be measured using a screw gauge.

A screw gauge can be used to determine the uniform thickness of any shape.

Ques. What are the different types of errors in a screw gauge?

Ans. Screw gauge errors can be classified into three types: zero error, positive error, and negative error. 

Zero error occurs if the zero markings on the main scale and the thimble scale do not correspond when the anvil and the spindle touch. The total reading is always subtracted from zero error. 

Positive zero errors occur when the anvil and the spindle make contact, the thimble scale zero-mark advances beyond the main scale zero-mark. 

Negative zero errors occur when the anvil and spindle make contact, the thimble scale zero mark is left behind the main scale zero mark.

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Very Long Answers Questions [5 Marks Questions]

Ques. What is the difference between a screw gauge and a vernier caliper?

Ans. The following are the differences between a screw gauge and a vernier caliper

Ques. What are the advantages of using a screw gauge?

Ans. The advantages of using a screw gauge are

High Precision: A screw gauge is a precision measuring tool that can provide measurements with an accuracy of 0.01 mm.

Versatility: It is possible to use these instruments to measure both internal and external dimensions, which makes them versatile measurement tools.

Ease of Use: It is easy to use screw gauges, which provide straightforward measurements and are user-friendly.

Repeatable results: It is possible to reproduce measurements taken with a screw gauge very easily.

Durability: Keeping screw gauges well-maintained can ensure that they will last for a long time.

Ques. When a screw gauge of least count 0.01 mm is used to measure the diameter of a wire, the reading on the sleeve is found to be 1 mm and the reading on the thimble is found to be 27 divisions. 

What is the diameter of the wire in cm?

If the zero error is + 0.005 cm, what is the correct diameter?

Ans. Given:

The least count of the screw gauge, LC = 0.01 mm = 0.001 cm

The main scale reading of the screw gauge, MSR = 1 mm = 0.1 cm

The number. of divisions of circular heads in line with the baseline (p) = 27

Zero error = +0.005 cm

Circular scale reading is given by

CSR = p x LC

⇒ CSR = 27 x 0.001 = 0.027 cm

Diameter of the wire i.e. total reading is given by

D = MSR + CSR

⇒ D = 0.1 + 0.027 = 0.127 cm

The correct diameter of the wire is given by

D_o = Observed reading (D) - Zero error

⇒ D₀ = 0.127 - (+0.005) = 0.122 cm

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