# Fasteners and Threads Flashcards

1
Q

Most fasteners have a thread angle of what?

A

60 degrees

2
Q

The distance from point to point on a screw to a corresponding point on the next thread, measured parallel to the axis is called what?

A

The pitch

3
Q

The distance a screw thread advances axially in one turn is called what?

A

4
Q

The surface of a thread connecting the crest to the root is called what?

A

Flank or side

5
Q

For counterclockwise rotation what kind of thread is used?

A

6
Q

In threaded fasteners the first full thread of the nut next to the flat washer takes how much of the load?

A

50 percent, the next thread 25 percent, the remaining share the rest

7
Q

What does 3/4” - 10 UNC - 2A x 1-1/2” lg mean?

A
```3/4" nominal diameter
10 tpi
Unified National Coarse thread style
Class fit 2
A = external thread
1-1/2" length```
8
Q

Maximum looseness in the mating threads is what class?

A

Class 1

9
Q

Average fit with little play in threads for everyday shop bolts are what class?

A

Class 2

10
Q

No looseness in mating threads are which class?

A

Class 3

11
Q

Precision threads in a micrometer is which class?

A

Class 4

12
Q

Extremely precise threads are which class?

A

Class 5&6

13
Q

60 degree thread angle with flats on the crest and root are which type of threads?

A

American National Threads - National Coarse and National Fine most common

14
Q

60 degree thread angle with a rounded root are which type of thread?

A

15
Q

The threads in this series have the same pitch for all diameters

A

Constant pitch series

16
Q

This thread is not for a fastener, has flat crest and roots, and a 29 degree angle. Used on a lathe

A

17
Q

This tapered thread seals a joint, preventing leakage

A

National Pipe Taper (NPT)

18
Q

M8 x 1.25 x 50 mm means?

A

Metric
8 - Nominal diameter
1.25 the pitch in mm
50mm - length

19
Q

What the difference between a bolt and screw?

A

The screw is loaded by the head, and a bolt is loaded or tightened by a nut

20
Q

A rod that is threaded on both ends is called what?

A

A stud

21
Q

The head markings on a bolt head indicate what?

A

Tensile strength

22
Q

What type of bolts are used when a smooth round head is required?

A

Carriage bolts

23
Q

The most common bolt head is

A

24
Q

These bolt heads must be turned 90 degrees before the wrench can be relocated on the head

A

25
Q

Cap screws start at what size?

A

1/4”

26
Q

This type of nut are locking nuts that also use a cotter pin

A

Castellated nut

27
Q

These nuts withstand greater torque and a larger flat surface than a Hex nut

A

Square nut

28
Q

When used to lock a regular nut the jam nut should be between the hex nut and joint surface because?

A

The hex nut takes the full bolt load

29
Q

A thinner version of a jam nut is called?

A

Palnuts

30
Q

The size of any internal thread is identified by what?

A

The major thread diameter and thread pitch of the bolt that would fit the nut

31
Q

Machine screws come in sizes as big as

A

3/8”

32
Q

How do you find that diameter of a machine screw?

A

Start as 0.060 and add 0.013 for every screw number increase

33
Q

These are used under bolt heads to increase the bearing surface of the fastener and protect from damage

A

Flat plain washer

34
Q

These washers are used to keep nuts and bolts from becoming loose from vibration

A

Split-ring lock washers

35
Q

These are thicker and stronger than than Split washers

A

Hi-collar lock washers

36
Q

These washers use teeth and are used when extra holding power is required

A

Tooth-lock washers

37
Q

What is the ratio of a taper pin?

A

1/4” per foot (1:48)

38
Q

What are used to align two machinery parts?

A

Dowel pins

39
Q

These pins are designed to break under greater than normal loads

A

Shear pins

40
Q

These pins are hollow, oversize and compress when driven into place to hold the parts in place

A

Spring pins and roll (coiled) pins

41
Q

These pins expand when driven into place and have tremendous holding power

A

Grooved pins

42
Q

These are used instead of cotter pins when they must be removed frequently

A

Spring-locking pins (hairpin cotters)

43
Q

The three taps used for different stages of a cut

A

Taper, Plug, Bottoming

44
Q

This is used to hold the tap securely and that even forces are applied

A

Tap wrenches

45
Q

How do you determine the tap size of a hole?

A

Tap drill size = nominal diameter - pitch

Reminder, pitch =1/pitch

46
Q

What are used to cut external threads?

A

A die

47
Q

What is the proper process for using a tap?

A

Back a quarter turn, forward half a turn

48
Q

What tool is used to hold a die?

A

Die stock

49
Q

Elongation of the bolt is called

A

Tension

50
Q

The tendency of the wedge shape of the thread to enlarge the diameter of the nut is called

A

Dilation

51
Q

The amount a fastener can be stretched and still return to its original length is called

A

Elastic limit

52
Q

Where the fastener begins to take a permanent set

A

Yield point

53
Q

The failure or breaking point of a bolt

A

Ultimate tensile strength

54
Q

Tensile forces are measured in

A

per square inch (psi)

55
Q

Tightening a nut and bolt assembly to a predetermined torque value is known as

A

56
Q

These bolts provide visual evidence that the desired preload value has been reached

A

57
Q

What are the types of torque wrenches?

A

Torque-limiting, dial indicating, deflecting beam

58
Q

This toque wrench is used where high torque is required to tighten fasteners

A

Hydraulic torque wrench