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Basic Information On Threads Properties, Drawings & Annotation

This document provides basic information about threads including definitions of terms like lead, pitch, and pitch diameter. It describes common thread types like metric, British Standard, trapezoidal, and buttress threads. Examples are given of how to annotate thread type, size, and other properties. The document also contains drawings that illustrate exact, simplified, and symbolic representations of fasteners like bolts, nuts, and screws.

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Vignesh Waran
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35 views5 pages

Basic Information On Threads Properties, Drawings & Annotation

This document provides basic information about threads including definitions of terms like lead, pitch, and pitch diameter. It describes common thread types like metric, British Standard, trapezoidal, and buttress threads. Examples are given of how to annotate thread type, size, and other properties. The document also contains drawings that illustrate exact, simplified, and symbolic representations of fasteners like bolts, nuts, and screws.

Uploaded by

Vignesh Waran
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Basic information on threads

properties, drawings & annotation


for didactic purposes only

Piotr Grdkowski

home.agh.edu.pl/gradkow

Thread annotation
Thread type
Metric ISO

British Standard
Pipe (BSP)

Symbol

Describing parameters & units

coarse

Outer diameter [mm]

fine

Outer diameter [mm] x pitch[mm]

parallel

taper

R*
Rc*

Example
M12
M12x1,5
G1

inner pipe diameter [in]


R1

British Standard Whitworth

outer diameter [in]

5/32

Trapezoidal

Tr

outer diameter [mm] x lead [mm]

Tr24x5

Buttress

outer diameter [mm] x lead [mm]

S24x5

Round

Rd

outer diameter [mm] x lead [in]

Rd10x1/10

- R refers to external threads, Rc to internal ones

Definitions:
Lead - the distance along the screw's axis that is covered by one complete rotation of the
screw (360)
Pitch - the distance from the crest of one thread to the next
Remark: For single-start threads Lead=Pitch
Pitch diameter Dp diameter on which the distance between the flanks of the thread equals
p/2

Left-hand threads
To annotate a left-hand thread, at the end of the annotation symbol, an LH must be added.
Example:
Left-hand fine metric thread

M14x1,5LH
Multiple-start threads:
Example:
Trapezoidal double-start thread, outer diameter 42mm, lead 10mm, pitch 5mm:

Tr42x10(P5)
Combined annotation
Example:
Buttress left-hand double-start thread:

S48x16(P8)LH

Metric thread contour


internal thread (nut)

external thread (screw)


thread axis

Detailed drawing of screw heads


& nuts

Exact drawing

Type of fastener
countersunk head screw

cheese head screw

A
hex head bolt

stud-bolt

Nut

Simpliefied drawing

Symbolic
annotation

Exact, simplified and symbolic representation of fasteners


10
2
3
5
1

14
13

11

15

12

4
6
11
12
13
14
15

1 - stud-bolt
2, 10 - nut
3, 9- washer
4 - blind tapped
hole
5 - clearance hole
6 - hex-head bolt
7,8 - clearance hole

- clearance hole
- blind tapped hole
- cheese head screw
- counterbored clearance hole
- clearance tapped hole

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