15 Threads and Fasteners Flashcards

Questions and Answers

The major diameter is the ________ diameter of the thread.

largest

The minor diameter is the ________ diameter of the thread.

smallest

The units of pitch are mm or inches per _______________.

thread

What are the two most common thread forms?

unified and metric screw threads Signup and view all the answers

External threads may be cut using a ________.

die or on a lathe Signup and view all the answers

Internal thread may be cut using a _________.

tap Signup and view all the answers

A tap drill is used when manufacturing _____________ threads.

internal Signup and view all the answers

In the thread notation 1/4 - 20 UNC, what is 20?

20 threads per inch; pitch = 1/20 Signup and view all the answers

In the thread notation 1/2 - 13 UNC, what is UN?

thread form: Unified National Signup and view all the answers

In the thread notation 3/8 - 24 UNF, what is F?

thread series: fine Signup and view all the answers

In the notation 5/8 - 24 UNEF -- 2A - RH, what is 2?

thread class: 2, normal production fit Signup and view all the answers

In the notation 1 - 8 UNC -- 3B - RH, what is B?

'B' for internal threads Signup and view all the answers

In the notation 1/2 - 20 UNF -- 2B - LH, what is LH?

left handed threads Signup and view all the answers

In the notation #10 - 24 UNC, what is #10?

major diameter Signup and view all the answers

In the notation M5 x 0.8, M stands for ______________.

metric thread form Signup and view all the answers

In the notation M4 x 0.7, what is 4?

major diameter Signup and view all the answers

In the notation M12 x 1.25, what is 1.25?

pitch (1.25 mm per thread) Signup and view all the answers

In the notation M6 x 1 -- 4h6h -- RH, what is 4h6h?

tolerance class Signup and view all the answers

Which one is the fine thread in M20 x 2.5 and M20 x 1.5?

M20 x 1.5 Signup and view all the answers

The schematic thread symbol draws lines at every crest and _______________.

root Signup and view all the answers

The simplified thread symbol uses a _____________ line to represent the minor diameter on external threads.

hidden Signup and view all the answers

How much longer is the tap drill depth than the thread depth when using a taper tap?

3 times the pitch Signup and view all the answers

The tap drill diameter is closest in size to the __________ diameter.

minor Signup and view all the answers

A bolt or screw clearance hole diameter depends on what factors?

major diameter, fit Signup and view all the answers

A standard parts sheet contains enough information about the standard parts so that they may be...

purchased Signup and view all the answers

A standard parts sheet contains drawings of all purchased parts.

False Signup and view all the answers

Study Notes

Thread Characteristics

Major diameter refers to the largest diameter of a thread.
Minor diameter indicates the smallest diameter of a thread.

Thread Measurement Units

Pitch is measured in either millimeters or inches per thread.

Common Thread Forms

Two most frequent thread forms are unified and metric screw threads.

Thread Cutting Techniques

External threads can be cut using a die or lathe.
Internal threads are created with a tap.
A tap drill is essential for manufacturing internal threads.

Unified National Thread Designations

In 1/4 - 20 UNC, "20" signifies 20 threads per inch, resulting in a pitch of 1/20.
"UN" in 1/2 - 13 UNC indicates it is a Unified National thread form.
In 3/8 - 24 UNF, "F" denotes fine thread series.

Thread Classes and Types

In 5/8 - 24 UNEF -- 2A - RH, "2" denotes a thread class for normal production fit.
"B" in 1 - 8 UNC -- 3B - RH represents internal threads.
"LH" in 1/2 - 20 UNF -- 2B - LH indicates left-handed threads.
"#10" in #10 - 24 UNC corresponds to the major diameter.

Metric Thread Designations

"M" in M5 x 0.8 signifies a metric thread form.
The number "4" in M4 x 0.7 reflects the major diameter.
In M12 x 1.25, "1.25" indicates pitch, which is 1.25 mm per thread.
"4h6h" in M6 x 1 -- 4h6h -- RH represents the tolerance class.
M20 x 1.5 is identified as a fine thread in comparison to M20 x 2.5.

Thread Symbolization

The schematic thread symbol includes lines drawn at both the crest and the root of the thread.
Simplified thread symbols employ a hidden line to depict the minor diameter on external threads.

Tap Drill and Clearance Hole Specifications

When using a taper tap, the tap drill depth extends 3 times the pitch beyond the thread depth.
The tap drill diameter closely matches the minor diameter of the thread.
The clearance hole diameter for bolts or screws depends on the major diameter and the desired fit.

Standard Parts Sheet

Standard parts sheets include sufficient information for purchasing standard parts.
It is incorrect to claim that these sheets contain drawings of all purchased parts.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge of threads and fasteners with these 15 flashcards. Each card covers key terms and definitions, helping you to master the concepts of thread diameters, pitch, and common thread forms. Perfect for students and professionals alike.