Fastening Technology Examination
FASTENING TECHNOLOGY | EXAM QUESTIONS AND
CORRECT ANSWERS | VERIFIED MECHANICAL
FASTENING AND JOINT DESIGN
FASTENING TECHNOLOGY
1. Which term describes the distance from a point on one thread to the
corresponding point on the next adjacent thread, measured parallel to
the axis?
A. Lead
B. Pitch
C. Major diameter
D. Thread depth
B. Pitch
Pitch is the axial distance between adjacent threads; lead is the distance a
screw advances in one full turn.
2. On a double-start thread, the lead is equal to:
A. Half the pitch
B. Twice the pitch
C. Three times the pitch
D. The pitch
B. Twice the pitch
Lead equals pitch multiplied by the number of starts, so a double-start
thread advances two pitches per revolution.
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,Fastening Technology Examination
3. The largest diameter of an external or internal screw thread is called
the:
A. Pitch diameter
B. Minor diameter
C. Root diameter
D. Major diameter
D. Major diameter
The major diameter is measured from crest to crest on an external thread
and root to root on an internal thread.
4. In the designation 1/2-13 UNC-2A, the number 13 indicates:
A. Bolt grade
B. Tolerance class
C. Threads per inch
D. Thread length in millimetres
C. Threads per inch
In Unified designations the second number is threads per inch; 13 TPI is
the coarse series for a 1/2 in. diameter.
5. In the Unified thread designation 3/8-24 UNF-2B, the letter B
identifies the thread as:
A. Left-handed
B. External
C. Internal
D. Coarse series
C. Internal
A designates external threads and B designates internal threads in the
Unified system.
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,Fastening Technology Examination
6. The included angle of a Unified National and ISO metric thread form
is:
A. 60°
B. 55°
C. 29°
D. 47.5°
A. 60°
Both Unified and ISO metric threads use a 60° included angle; 55° is
Whitworth and 29° is Acme.
7. A metric thread designated M10 × 1.5 has a pitch of:
A. 10 mm
B. 1.5 mm
C. 0.15 mm
D. 15 threads per mm
B. 1.5 mm
In metric notation the number following the × is the pitch in millimetres.
8. Which thread class provides the tightest tolerance in the Unified
system?
A. 3A/3B
B. 1A/1B
C. 2A/2B
D. 4A/4B
A. 3A/3B
Class 3 offers the closest tolerances; Class 2 is the general commercial
standard and Class 1 the loosest.
9. Which thread form is most commonly used for power transmission
in lead screws and vises?
A. Unified coarse
B. Whitworth
C. Pipe thread
D. Acme
D. Acme
The 29° Acme thread has a strong, flat-crested profile well suited to
transmitting motion and load.
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, Fastening Technology Examination
10. A buttress thread is designed primarily to:
A. Seal pipe connections
B. Resist vibration loosening
C. Carry high loads in one direction
D. Allow quick assembly in either direction
C. Carry high loads in one direction
The buttress profile has one near-vertical flank to take heavy axial thrust
in a single direction.
11. NPT pipe threads seal primarily because they are:
A. Rolled rather than cut
B. Left-handed
C. Tapered
D. Fine pitch
C. Tapered
The 1:16 taper of NPT threads wedges the flanks together; sealant is still
normally used to fill the spiral leak path.
12. The taper of a standard NPT thread is:
A. 1 in 12 on diameter
B. 1 in 16 on diameter
C. 1 in 8 on diameter
D. 1 in 32 on diameter
B. 1 in 16 on diameter
NPT tapers 1/16 in. per inch on diameter, which equals 3/4 in. per foot.
13. A left-hand thread is typically used when:
A. Fine adjustment is required
B. Rotation in service would tend to loosen a right-hand thread
C. The fastener must be removed frequently
D. Maximum tensile strength is needed
B. Rotation in service would tend to loosen a right-hand thread
Left-hand threads are fitted where normal operating rotation would
otherwise unscrew a right-hand fastener, such as on some pedals and
grinder spindles.
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FASTENING TECHNOLOGY | EXAM QUESTIONS AND
CORRECT ANSWERS | VERIFIED MECHANICAL
FASTENING AND JOINT DESIGN
FASTENING TECHNOLOGY
1. Which term describes the distance from a point on one thread to the
corresponding point on the next adjacent thread, measured parallel to
the axis?
A. Lead
B. Pitch
C. Major diameter
D. Thread depth
B. Pitch
Pitch is the axial distance between adjacent threads; lead is the distance a
screw advances in one full turn.
2. On a double-start thread, the lead is equal to:
A. Half the pitch
B. Twice the pitch
C. Three times the pitch
D. The pitch
B. Twice the pitch
Lead equals pitch multiplied by the number of starts, so a double-start
thread advances two pitches per revolution.
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,Fastening Technology Examination
3. The largest diameter of an external or internal screw thread is called
the:
A. Pitch diameter
B. Minor diameter
C. Root diameter
D. Major diameter
D. Major diameter
The major diameter is measured from crest to crest on an external thread
and root to root on an internal thread.
4. In the designation 1/2-13 UNC-2A, the number 13 indicates:
A. Bolt grade
B. Tolerance class
C. Threads per inch
D. Thread length in millimetres
C. Threads per inch
In Unified designations the second number is threads per inch; 13 TPI is
the coarse series for a 1/2 in. diameter.
5. In the Unified thread designation 3/8-24 UNF-2B, the letter B
identifies the thread as:
A. Left-handed
B. External
C. Internal
D. Coarse series
C. Internal
A designates external threads and B designates internal threads in the
Unified system.
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,Fastening Technology Examination
6. The included angle of a Unified National and ISO metric thread form
is:
A. 60°
B. 55°
C. 29°
D. 47.5°
A. 60°
Both Unified and ISO metric threads use a 60° included angle; 55° is
Whitworth and 29° is Acme.
7. A metric thread designated M10 × 1.5 has a pitch of:
A. 10 mm
B. 1.5 mm
C. 0.15 mm
D. 15 threads per mm
B. 1.5 mm
In metric notation the number following the × is the pitch in millimetres.
8. Which thread class provides the tightest tolerance in the Unified
system?
A. 3A/3B
B. 1A/1B
C. 2A/2B
D. 4A/4B
A. 3A/3B
Class 3 offers the closest tolerances; Class 2 is the general commercial
standard and Class 1 the loosest.
9. Which thread form is most commonly used for power transmission
in lead screws and vises?
A. Unified coarse
B. Whitworth
C. Pipe thread
D. Acme
D. Acme
The 29° Acme thread has a strong, flat-crested profile well suited to
transmitting motion and load.
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, Fastening Technology Examination
10. A buttress thread is designed primarily to:
A. Seal pipe connections
B. Resist vibration loosening
C. Carry high loads in one direction
D. Allow quick assembly in either direction
C. Carry high loads in one direction
The buttress profile has one near-vertical flank to take heavy axial thrust
in a single direction.
11. NPT pipe threads seal primarily because they are:
A. Rolled rather than cut
B. Left-handed
C. Tapered
D. Fine pitch
C. Tapered
The 1:16 taper of NPT threads wedges the flanks together; sealant is still
normally used to fill the spiral leak path.
12. The taper of a standard NPT thread is:
A. 1 in 12 on diameter
B. 1 in 16 on diameter
C. 1 in 8 on diameter
D. 1 in 32 on diameter
B. 1 in 16 on diameter
NPT tapers 1/16 in. per inch on diameter, which equals 3/4 in. per foot.
13. A left-hand thread is typically used when:
A. Fine adjustment is required
B. Rotation in service would tend to loosen a right-hand thread
C. The fastener must be removed frequently
D. Maximum tensile strength is needed
B. Rotation in service would tend to loosen a right-hand thread
Left-hand threads are fitted where normal operating rotation would
otherwise unscrew a right-hand fastener, such as on some pedals and
grinder spindles.
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