10.1 Draw a neat sketch of a metric V-screw thread and indicate the THREE diameters of the screw thread. 10.2 Explain what is meant by the lead of a screw thread. 10.3 A three-start square thread with a 4 mm pitch must be cut on a lathe. The crest diameter of the thread is 68 mm and the clearance angle is 3°. Calculate the following: 10.3.1 The lead of the thread. 10.3.2 The mean circumference of the thread. 10.3.3 The helix angle of the thread. 10.3.4 The leading tool angle. 10.3.5 The following tool angle.

NSC Mechanical Technology Fitting and Machining Calculations on size of drills for bolts and nuts (Square thread): 10.1 Draw a neat sketch of a met

10.1 Draw a neat sketch of a metric V-screw thread and indicate the THREE diameters of the screw thread - NSC Mechanical Technology Fitting and Machining - Question 10 - 2019 - Paper 1

Question 10

10.1-Draw-a-neat-sketch-of-a-metric-V-screw-thread-and-indicate-the-THREE-diameters-of-the-screw-thread-NSC Mechanical Technology Fitting and Machining-Question 10-2019-Paper 1.png

10.1 Draw a neat sketch of a metric V-screw thread and indicate the THREE diameters of the screw thread. 10.2 Explain what is meant by the lead of a screw thread. ... show full transcript

Worked Solution & Example Answer:10.1 Draw a neat sketch of a metric V-screw thread and indicate the THREE diameters of the screw thread - NSC Mechanical Technology Fitting and Machining - Question 10 - 2019 - Paper 1

Step 1

Draw a neat sketch of a metric V-screw thread and indicate the THREE diameters of the screw thread.

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Answer

A neat sketch of a metric V-screw thread should include the following diameters:

Pitch Diameter (A): The diameter at which the width of the thread and the width of the groove are equal.
Minor Diameter (B): The diameter measured at the root of the thread (the smallest diameter).
Major Diameter (C): The diameter measured at the crest of the thread (the largest diameter).

The sketch should clearly label these dimensions.

Step 2

Explain what is meant by the lead of a screw thread.

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Answer

The lead of a screw thread is defined as the distance that a thread will advance axially in one complete revolution. It can be calculated using the formula:

$ext{Lead} = ext{Pitch} imes ext{Number of Starts}$

In this case, for a three-start square thread with a pitch of 4 mm:

$ext{Lead} = 4 ext{ mm} imes 3 = 12 ext{ mm}$

Step 3

Calculate the following:

96%

101 rated

Answer

10.1 Draw a neat sketch of a metric V-screw thread and indicate the THREE diameters of the screw thread - NSC Mechanical Technology Fitting and Machining - Question 10 - 2019 - Paper 1

Worked Solution & Example Answer:10.1 Draw a neat sketch of a metric V-screw thread and indicate the THREE diameters of the screw thread - NSC Mechanical Technology Fitting and Machining - Question 10 - 2019 - Paper 1

Draw a neat sketch of a metric V-screw thread and indicate the THREE diameters of the screw thread.

Explain what is meant by the lead of a screw thread.

Calculate the following:

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