Chapter 5: Screw Thread Measurement

The major diameter of an external screw thread is measured:

• From root to root

• From crest to crest

• At the pitch line

• Using the three-wire method

The minor diameter of an internal thread is:

• Largest diameter of the thread

• Diameter at which the thread thickness equals the space

• Smallest diameter of the thread

• Diameter from crest to root

In screw thread measurement, the pitch is:

• The number of threads per unit length

• The distance between two adjacent crests, measured parallel to the axis

• The angle between thread flanks

• The diameter at the root of the thread

Which method is used for the most accurate pitch diameter measurement?

• Thread micrometer

• Vernier caliper

• Three-wire method

• Optical comparator

Which of the following errors can occur in screw threads?

• Pitch error
  

• Lead error

• Angle error

• All of the above

Accurate measurement of pitch diameter in both screws and gears is important mainly to:

• Improve tool life

• Ensure proper mating and load distribution

• Increase surface roughness

• Reduce manufacturing cost

The ISO metric screw thread profile has a flank angle of:

• 55°

• 60°

• 30°

• 75°

Which of the following is NOT a common screw thread form?

• Acme thread

• Square thread

• Trapezoidal thread

• Hexagonal thread

The lead of a single-start screw thread is:

• Equal to its pitch

• Twice its pitch

• Half its pitch

• Independent of pitch

Which statement correctly describes screw thread measurement?

• Screw threads are measured only by their outside diameter using a caliper.

• The screw thread micrometer uses interchangeable anvils to measure the pitch diameter accurately.

• All screw threads have the same profile angle regardless of standard.

• Thread pitch can only be checked with a profile projector.