Screw Threads + Nuts

Question 1

Form

Answer 1

Contour crest to crest

Question 2

Crest

Answer 2

Top of thread, prominent point

Question 3

Root

Answer 3

Bottom of thread groove

Question 4

Flank

Answer 4

Slope from root to crest

Question 5

Thread angle

Answer 5

Angle between flanks

Question 6

Major diameter in male

Answer 6

Diameter from crest to crest

Question 7

Major diameter in female

Answer 7

Diameter from root to root

Question 8

Minor diameter in male

Answer 8

Diameter from root to root

Question 9

Minor diameter in female

Answer 9

Diameter from crest to crest

Question 10

Depth

Answer 10

Radial Distance from root to crest

Question 11

Pitch

Answer 11

Distance from crest to crest

Question 12

Lead

Answer 12

Distance advanced by the moving body of a mating pair in one complete rotation

Question 13

Run-out

Answer 13

Where the minor diameter increases until it reaches major diameter (flank leading to plain part of screw)

Question 14

British standard whitworth characteristics

Answer 14

Course, general purpose, 55 degree thread angle

Question 15

British Standard Fine characteristics

Answer 15

• Finer than BSW
• Resists vibration
• Used on aircraft and vehicles
• 55 degree thread angle

Question 16

British Standard Pipe characteristics

Answer 16

• Used in couplings
• Requires more material
• Have tapered crests
• 55 degree thread angle

Question 17

British Associations characteristics

Answer 17

• Less than quarter inch diameter
• Scaled from 0-10 (10 =smallest)
• Used is small electrical parts
• 47.5 degree thread angle

Question 18

American National Coarse characteristics

Answer 18

• Flat crest and root

- 60 degrees thread angle

Question 19

American National Fine characteristics

Answer 19

• Finer than ANC

- 60 degree thread angle

Question 20

What are the 3 categories of Unified thread forms and what are their thread angles?

Answer 20

• Unified National Course (UNC)
• Unified National Fine (UNF)
• Unified National Extra Fine (UNEF)
• All have a 60 degree thread angle

Question 21

What tool is used to determine thread form

Answer 21

Screw pitch gauge/thread gauge

Question 22

What 3 types of thread are used primarily as transmission threads. Used in screw jacks, lifting tackle and parts of heavy industrial machinery?

Answer 22

Square, Buttress and Acme

Question 23

What is unique about Buttress threads?

Answer 23

Can only transmit power in one direction

Question 24

Which type of thread is the most common?

Answer 24

Symmetrical V thread

Question 25

Where does a screw tighten

Answer 25

Into a threaded hole

Question 26

What does Chamfered mean?

Answer 26

A Lead has been filed into the thread

Question 27

What must grip length equal when fitting a bolt

Answer 27

The thickness of the material

Question 28

Where should bolts be identified from?

Answer 28

International Parts Catalogue (IPC)

Question 29

What does the part number break down into?

Answer 29

Grip length, diameter, drillings and finish

Question 30

What are bolts identified by other than part number?

Answer 30

Code marking

Question 31

How many threads threads are permitted in the hole for materials thicker than 2.4mm?

Answer 31

2

Question 32

How many threads are permitted in the hole for materials thinner than 2.4mm?

Answer 32

0

Question 33

What is the maximum number of washers that can be used to alter grip length?

Answer 33

3

Question 34

Why would you use a waisted stud?

Answer 34

It uses less material

Question 35

Which stud provides the most rigidity?

Answer 35

Shouldered stud

Question 36

What sort of material is a stepped stud used in and why?

Answer 36

Soft materials due to increased Anchorage

Question 37

What 3 factors are studs categorised by?

Answer 37

- Tread type - Diameter - Overall length

Question 38

What are the 3 methods of fitting a stud

Answer 38

- Stud box - Stud insertion tool - Lock nuts

Question 39

What are the 3 methods of removing a stud?

Answer 39

- Lock nut - Filing flats and using an appropriate spanner to remove - Ezi-outs

Question 40

What type of metal are self tapping screws used for?

Answer 40

Thin gauge sheet metal

Question 41

What should self tapping screws not be used as?

Answer 41

Replacements for standard bolts and screws

Question 42

What is used to lock down a castle nut?

Answer 42

A split pin

Question 43

What is the difference between a castle nut as a shear castle nut?

Answer 43

Shear castle nut is used on areas with a lower tensile load

Question 44

Which type of crenellated nut is designed for high temperature areas and is not approved for airframe use?

Answer 44

Slotted engine nut

Question 45

Where are wing nuts used and why?

Answer 45

Frequently opened areas because they can be tightened and loosened by hand

Question 46

What do plain nuts require to work?

Answer 46

Locking devices

Question 47

What is a check nut used for?

Answer 47

As a locking device for plain nuts

Question 48

What type of lock does a lock nut create?

Answer 48

Friction lock

Question 49

What type of nut has an insert that will melt if used in a high temperature environment?

Answer 49

Nyloc stiff nut

Question 50

How does an Oddie nut work?

Answer 50

6 springy tongues that are bent inward form a circle with a diameter less than the diameter of the root of the bolt thread, this grips the bolt thread in place

Question 51

How do you tell the difference between an Aerotight and Philidas nut?

Answer 51

Aerotight has a vertical cut on the head, Philidas has a Horizontal cut on the head

Question 52

What type of nut is fixed permanently in place?

Answer 52

Anchor nuts

Question 53

Where are Anchor nuts used?

Answer 53

In areas you can’t get access to where screws need to be removed and refitted on a regular basis, such as panels

Question 54

At what temperature are High temperature self locking nuts used?

Answer 54

120 degrees Celsius or higher

Question 55

What is the maximum temperature at which Low temperature self locking nuts used?

Answer 55

121 degrees Celsius

Question 56

What metal alloys are High temperature self locking nuts usually used with?

Answer 56

CRES, Steel alloy and silver plated CRES

Question 57

What type of self locking nut has it’s threads out of phase?

Answer 57

High temperature self locking nuts