Nuts bolts-screws-washers

Standards for nuts, bolts, screws and washers

1. ISO metric precision hexagon bolts, screws and nuts
are covered by BS 3643 and ISO 272. The standard
includes washer faced hexagon head bolts and full
bearing head bolts. In both cases there is a small radius
under the bolthead which would not normally be shown
on drawings, due to its size, but is included here for
completeness of the text. With an M36 bolt, the radius
is only 1.7 mm. Bolts may be chamfered at 45° at the
end of the shank, or radiused. The rounded end has a
radius of approximately one and one quarter times the
shank diameter and can also be used if required to
draw the rolled thread end. The washer face under the
head is also very thin and for a M36 bolt is only
0.5 mm.
Figure 10.1(a) shows the bolt proportions and Table
10.1 the dimensions for bolts in common use.
Dimensions of suitable nuts are also given and illustrated
in Fig. 10.1(b).
Included in Table 10.1 and shown in Fig. 10.1(c)
are typical washers to suit the above bolts and nuts
and these are covered by BS 4320. Standard washers
are available in two different thicknesses, in steel or
brass, and are normally plain, but may be chamfered.
Table 10.1 gives dimensions of commonly used bolts,
nuts and washers so that these can be used easily on
assembly drawings. For some dimensions maximum
and minimum values appear in the standards and we
have taken an average figure rounded up to the nearest
0.5 mm and this will be found satisfactory for normal
drawing purposes. Reference should be made to the
relevant standards quoted for exact dimensions if
required in design and manufacture.
Drawing nuts and bolts
It is often necessary to draw nuts and bolts and a quick
easy method is required to produce a satisfactory result.
Chapter 10
Nuts, bolts, screws and washers
Table 10.1
D A/C A/F Df H T t
M1.6 0.35 1.1 3.5 3.0 1.0 1.25 1.7 4.0 0.3
M2 0.4 1.4 4.5 4.0 1.5 1.5 2.2 5.0 0.3
M2.5 0.45 1.9 5.5 5.0 1.75 2.0 2.7 6.5 0.5
M3 0.5 2.3 6.0 5.5 5.0 2.0 2.25 3.2 7.0 0.5
M4 0.7 3.0 8.0 7.0 6.5 2.75 3.0 4.3 9.0 0.8
M5 0.8 3.9 9.0 8.0 7.5 3.5 4.0 5.3 10.0 1.0
M6 1.0 4.7 11.5 10.0 9.0 4.0 5.0 6.4 12.5 1.6 0.8
M8 1.25 6.4 15.0 13.0 12.0 5.5 6.5 5.0 8.4 17 1.6 1.0
M10 1.5 8.1 19.5 17.0 16.0 7.0 8.0 6.0 10.5 21 2.0 1.25
M12 1.75 9.7 21.5 19.0 18.0 8.0 10.0 7.0 13.0 24 2.5 1.6
M16 2.0 13.5 27.0 24.0 23.0 10.0 13.0 8.0 17.0 30 3.0 2.0
M20 2.5 16.7 34.0 30.0 29.0 13.0 16.0 9.0 21.0 37 3.0 2.0
M24 3.0 20.0 41.5 36.0 34.5 15.0 19.0 10.0 25.0 44 4.0 2.5
M30 3.5 25.5 52.0 46.0 44.5 19.0 24.0 12.0 31.0 56 4.0 2.5
M36 4.0 31.0 62.5 55.0 53.5 23.0 29.0 14.0 37.0 66 5.0 3.0
Nominal
size thread
diameter
Thread
pitch
Minor
diameter
of thread
Width
across
corners
Width
across
flats
Diameter
of washer
face
Height of
bolt head
Thickness
of normal
nut
Thickness
of thin nut
Washer
inside
diameter
Washer
outside
diameter
Washer
thickness
Form A
Washer
thickness
Form BMCE 310 (Machine Drawing) Lectures by Kilanko O. 77

2. Nuts and bolts are not normally drawn on detail
drawings unless they are of a special type. They are
shown on assembly drawings and, provided they are
standard stock sizes, are called up in parts lists and
schedules. A description of the head, the thread and
the length being generally sufficient. Templates are
available for drawing nuts and bolts and can be
recommended for their time saving advantages.
It is conventional drawing practice to show, as first
choice, nuts and bolts in the across corners position if
a single view only is illustrated since this is instantly
recognizable.
Approximate construction
for nuts and bolts (Figs
10.2 and 10.3)
Stage 1
1 Draw a circle in the plan position, 2D in diameter,
where D is equal to the thread size. In this example
let us assume that the thread size is M20.
2 Draw a hexagon inside the 40 mm diameter circle
and inside the hexagon draw another circle tangential
to the hexagon on the six sides. This circle is the
projection of the chamfer which can be seen on the
front elevation.
3 the nut thickness is 0.8D. Project the four corners
of the hexagon to the front elevation.
4 Project three corners of the hexagon in the end
elevation and note, that the width of the end elevation
is given by dimension W.
5 Line in the projected diameter of the chamfer circle
and the base in the front elevation.
6 As an approximation, draw a radius to show the
chamfer on the front elevation. The radius should
equal the thread size D.
7 Add the female convention to the plan view.
(b) Precision nuts and thin nuts
A/F
D
A/C
T t
(a) Hexagon head precision bolts
Rolled thread end
Full bearing head (c)
Bright washers
d1
d2
Form A Form B
SS
Chamfer
optional
30°
Hexagon head
washer faced
H
Df
Length
D
A/F
A/C
1
1
4
D
Fig. 10.1 Proportions of bolts, nuts and washers. A/C means across corners. A/F means across flats.
W
0.8D
D
D
W
2D
Fig. 10.2 Stage 1MCE 310 (Machine Drawing) Lectures by Kilanko O. 78

3. Stage 2
1 The projection of the curve on the chamfered faces
of the hexagon that lie at an angle would produce
ellipses in the front elevation. In their place we
usually show small circular arcs, their radii can be
found by trial, but are approximately 0.25D.
2 The end elevation of the nut has square corners and
the projection of the corner which coincides with
the centre line terminates at the bottom of the
chamfer curve.
3 Complete the view by drawing circular arcs on the
two chamfered faces. Find by trial, the radius of an
arc which will touch the top of the nut and the
projection lines from the corner in the front elevation.
Reference to Fig. 10.1a and b will show that the
constructions in Fig. 10.2 and Fig. 10.3 can be used
for the bolthead and locknut where proportions for
thickness can be approximated to 0.7D and 0.5D.
For exact dimensions however, please refer to Table
10.1.
Socket head screws manufactured to
BS EN ISO 4762 and BS 3643-2
It is often required to draw these screws and although
the head type and the length are generally quoted in
parts lists it is necessary to know the proportions of
the head. Dimensions follow for each of the most
commonly used screws.
Before specifying screws it is advisable to consult a
manufacturers list for availability. In the interest of
standardization and economy, designers are urged to
use stock lengths wherever possible and standard lengths
of screws include the following; 3, 4, 5, 6, 8, 10, 12,
16, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80,
90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190,
and 200 mm. If lengths over 200 mm are required,
then increments of 20 mm are the preferred ISO lengths.
It should be understood that not all diameters of screw
are available in the above lengths. For example, the
range of lengths for an M3 screw lies between 5 and
35 mm, for an M10 screw between 12 and 100 mm for
one particular type of head. The same range will also
not cover different types of head, hence the necessity
to check stock lists.
ISO metric socket cap screws
Dimensions in Table 10.2
These screws are distinguished by square knurling on
the heads. Generally, the lengths of standard screws
increase in increments of 5 mm and 10 mm, but the
exact range should be checked from the manufacturers
catalogue.
Fig. 10.3 Stage 2
Table 10.2
Nominal size D M3 M4 M5 M6 M8 M10 M12 M16 M20
Head diameter A 5.5 7 8.5 10 13 16 18 24 30
Head depth H 3 4 5 6 8 10 12 16 20
Key engagement K 1.3 2 2.7 3.3 4.3 5.5 6.6 8.8 10.7
Socket size J 2.5 3 4 5 6 8 10 14 17
Fig. 10.4 ISO metric hexagon socket shoulder screws. Dimensions in
Table 10.3
A
D
K
H Screw length
Thread
length J
ISO metric hexagon socket shoulder
screws
Dimensions in Table 10.3
Table 10.3
Nominal shoulder diameter B 6 8 10 12 16
Head diameter A 10 13 16 18 24
Head height H 4.5 5.5 7 8 10
Socket size J 3 4 5 6 8
Screw thread diameter D M5 M6 M8 M10 M12
Nominal thread length Lt 9.75 11.25 13.25 16.4 18.4
Key engagement K 2.45 3.3 4.15 4.92 6.62
Fig. 10.5 ISO metric hexagon socket button head screws. Dimensions in
Table 10.4
J
Lt
D
B
LH
K
AMCE 310 (Machine Drawing) Lectures by Kilanko O. 79

4. ISO metric hexagon socket button head
screws
Dimensions in Table 10.4
and the minimum head angle of 90°. The minimum
head size is controlled by a minimum head diameter,
the maximum head angle of 92° and a flushness
tolerance. The edge of the head may be flat, as shown
in Fig. 10.8, or rounded but not sharp edged (see below).
Table 10.4
Nominal size D M3 M4 M5 M6 M8 M10 M12
Head diameter A 5.5 7.5 9.5 10.5 14 18 21
Head depth H 1.6 2.1 2.7 3.2 4.3 5.3 6.4
Key engagement K 2 2.5 3 4568
Socket size J 1.04 1.3 1.56 2.08 2.6 3.12 4.16
Fillet radius
F-minimum 0.1 0.2 0.2 0.25 0.4 0.4 0.6
da-maximum 3.6 4.7 5.7 6.8 9.2 11.2 14.2
S 0.38 0.38 0.5 0.8 0.8 0.8 0.8
Fig. 10.6
LS
D
da
FK
H
A
J
ISO metric socket countersunk
head screws
Dimensions in Table 10.5
The basic requirement for countersunk head screws is
that the head should fit into a countersunk hole with as
great a degree of flushness as possible. Fig. 10.7 and
Table 10.5 give dimensions. To achieve this it is
necessary for both the head of the screw and the
countersunk hole to be controlled within prescribed
limits. The maximum or design size of the head is
controlled by a theoretical diameter to a sharp corner
Table 10.5
Nominal size D M3 M4 M5 M6 M8 M10 M12 M16 M20
Head diameter
A – maximum 6.72 8.96 11.2 13.44 17.92 22.4 26.88 33.6 40.32
B – minimum 5.82 7.78 9.78 11.73 15.73 19.67 23.67 29.67 35.61
Head depth H 1.86 2.48 3.1 3.72 4.96 6.2 7.44 8.8 10.16
Socket size J 22 .5345681 01 2
Key engagement K 1.05 1.49 1.86 2.16 2.85 3.60 4.35 4.89 5.49
Fillet radius
F – minimum 0.1 0.2 0.2 0.25 0.4 0.4 0.6 0.6 0.8
da – maximum 3.4 4.5 5.5 6.6 9 11 14 18 22
Fig. 10.7
90°
B
A
K
H
Lt
F
L
D
da
Sharp corners removed
Flushness
tolerance
Maximum
profile
Minimum
profile
92°
Min. Head Dia.
Theoretical sharp
90°
Fig. 10.8 ISO metric hexagon socket set screws. Dimensions in
Table 10.6
ISO metric hexagon socket set screws
Dimensions in Table 10.6
These screws are available with a variety of pointed
ends. In all cases the overall length includes the chamfer
at the socket end and the point.
J
D
L
KMCE3 9M’3 4Machine3 Drawing73 Lectures3 by3 Kilanko3 OP 8’

5. ‘screws’ applies to products which are threaded up to
the head or having an unthreaded portion of the shank.
The length of the thread is defined as the distance
from the end of the screw, and this includes any chamfer,
radius or cone point, to the leading face of the nut
which has been screwed as far as possible onto the
screw by hand. Note on the illustrations which follow
that in the case of the countersunk head types of screw,
the length of the screw includes the countersunk part
of the head. For pan and cheese head screws, the screw
length does not include the head.
The Standard should be consulted for manufacturing
dimensional tolerances, also concentricity tolerances
for the heads of the screws.
The illustrations which follow show each of the
screws and tables are also given showing the dimensions
of regularly used sizes.
The sizes quoted in the tables are for screws
manufactured in steel. Standard screws are also available
in brass but generally the range is not quite so extensive.
For all of the machine screws illustrated here, the
countersunk head types have an included angle of 90°.
‘Posidriv’ machine screws, countersunk
and raised countersunk head
Dimensions in Table 10.7
Table 10.6
Nominal size D M3 M4 M5 M6 M8 M10 M12 M16 M20
Socket size J 1 .522 .53456 81 0
Key engagement K 1.2 1.6 2 2.4 3.2 4 4.8 6.4 8
Dog point diameter P 2 2.5 3.5 4.5 6791 21 5
Dog point length Q 0.88 1.12 1.38 1.62 2.12 2.62 3.12 4.15 5.15
Cup point and ‘ W’
point diameter C 1.4 2 2.5 35681 01 4
Note: The cone point angle shown as Y° is generally 118° for short screws and 90° for longer lengths.
Y°
P
Q
(b)(a)
90°
C
90° 118°
C
(d)(c)
Fig. 10.9 (a) Cone point (b) Dog point (c) W point (d) Cup point
Fig. 10.10 Typical GKN socket screws and wrench
d
L
H
D
Fig. 10.11 Countersunk head
d
D
H
L
Machine screws
Head shapes for machine screws have been rationalized
in BS EN ISO 1580 and BS EN ISO 7045. For the
purpose of this British Standard, the generic term
Fig. 10.12 Raised countersunk headMCE 310 (Machine Drawing) Lectures by Kilanko O. 81

6. ‘Posidriv’ machine screws, pan head
Dimensions in Table 10.8
Table 10.7
Diameter Dia of head Depth of head Driver Length
d D H no. L
M2 4.40 1.20 1 4 5 6 8 10 12
M2.5 5.50 1.50 1 5 6 8 10 12 16 20 25
M3 6.30 1.65 1 5 6 8 10 12 16 20 25
M3.5 7.35 1.93 2 6 8 10 12 16 20 25 30
M4 8.40 2.20 2 6 8 10 12 16 20 25 30
M5 10.00 2.50 2 6 8 10 12 16 20 25 30 35 40 45 50
M6 12.00 3.00 3 10 12 16 20 25 30 35 40 45 50 55 60
M8 16.00 4.00 4 12 16 20 25 30 40 50 60
M10 20.00 5.00 4 16 20 25 30 40 50 60
Slotted machine screws, countersunk
and raised countersunk head
Dimensions in Table 10.9
Table 10.8
Diameter Dia of head Depth of head Driver Length
d D H no. L
M2 4.00 1.60 1 4 5 6 8 10 12
M2.5 5.00 1.75 1 5 6 8 10 12 16 20 25
M3 6.00 2.10 1 5 6 8 10 12 16 20 25
M3.5 7.00 2.45 2 6 8 10 12 16 20 25 30
M4 8.00 2.80 2 5 6 8 10 12 16 20 25 30
M5 10.00 3.50 2 6 8 10 12 16 20 25 30 35 40 45 50
M6 12.00 4.20 3 10 12 16 20 25 30 35 40 45 50 55 60
M8 16.00 5.60 4 16 20 25 30 40 50
M10 20.00 7.00 4 20 25 30 40
HL
D
d
Fig. 10.13
L
H
D
d
D
d
H
L
Fig. 10.14 Countersunk head Fig. 10.15 Raised countersunk headMCE3 9M’3 4Machine3 Drawing73 Lectures3 by3 Kilanko3 OP 88

7. Slotted machine screws, cheese head
Dimensions in Table 10.11
Table 10.9
Diameter Dia of head Depth of head Length
dDH L
M2 4.40 1.20 5 6 8 10 12
M2.5 5.50 1.50 5 6 8 10 12 16 20 25
M3 6.30 1.65 5 6 8 10 12 16 20 25 30 35 40 45 50
M3.5 7.35 1.93 5 6 8 10 12 16 20 25 30 35 40 45 50 60
M4 8.40 2.20 5 6 8 10 12 16 20 25 30 35 40 45 50 60 70
M5 10.00 2.50 6 8 10 12 16 20 25 30 35 40 45 50 60 70 80
M6 12.00 3.00 8 10 12 16 20 25 30 35 40 45 50 60 70 80 90
M8 16.00 4.00 10 12 16 20 25 30 35 40 45 50 60 70 80 90
M10 20.00 5.00 16 20 25 30 35 40 45 50 55 60 70 80 90
Slotted machine screws, pan head
Dimensions in Table 10.10
Fig. 10.16
D
d
LH
Table 10.10
Diameter Dia of head Depth of Length
d D head H L
M2 4.00 1.20 4 5 6 8 10 12
M2.5 5.00 1.50 5 6 8 10 12 16 20 25
M3 6.00 1.80 5 6 8 10 12 16 20 25 30 35 40 45 50
M3.5 7.00 2.10 6 8 10 12 16 20 25 30 35 40 45 50
M4 8.00 2.40 5 6 8 10 12 16 20 25 30 35 40 45 50
M5 10.00 3.00 6 8 10 12 16 20 25 30 35 40 45 50 55 60 70 80
M6 12.00 3.60 8 10 12 16 20 25 30 35 40 45 50 55 60 70 80
M8 16.00 4.80 10 12 16 20 25 30 40 50 60 70 80 90
M10 20.00 6.00 16 20 25 30 40 50 60 70
Fig. 10.17
LH
d
DMCE3 9M’3 4Machine3 Drawing73 Lectures3 by3 Kilanko3 OP 89

8. Machine screw nuts
A range of machine screw nuts is covered by BS EN
ISO 1580 and BS EN ISO 7045 and these nuts are
manufactured in two different patterns, square and
hexagon. The table shows typical nuts for use with the
screws previously described.
Table 10.11Diameter Dia of head Depth of Length
d D head H L
M2 3.80 1.30 3 4 5 6 8 10 12 16 20 25
M2.5 4.50 1.60 5 6 8 10 12 16 20 25 30
M3 5.50 2.00 4 5 6 8 10 12 16 20 25 30 35 40 45 50
M3.5 6.00 2.40 5 6 8 10 12 16 20 25 30 35 40 45 50 60 70
M4 7.00 2.60 5 6 8 10 12 16 20 25 30 35 40 45 50 60 70
M5 8.50 3.30 6 8 10 12 16 20 25 30 35 40 45 50 60 70 80 90
M6 10.00 3.90 8 10 12 16 20 25 30 35 40 45 50 60 70 80 90
M8 13.00 5.00 10 12 16 20 25 30 35 40 45 50 60 70 80 90
M10 16.00 6.00 16 20 25 30 35 40 45 50 60 70 80 90
Table 10.12 Machine screw nuts, pressed type, square and hexagonal
Nominal size Width across Width across corners e Thickness
of nut d flats s
Square Hexagon
m
M2 4.0 5.7 4.6 1.2
M2.5 5.0 7.1 5.8 1.6
M3 5.5 7.8 6.4 1.6
M3.5 6.0 8.5 6.9 2.0
M4 7.0 9.9 8.1 2.0
M5 8.0 11.3 9.2 2.5
M6 10.0 14.1 11.5 3.0
M8 13.0 18.4 15.0 4.0
M10 17.0 24.0 19.6 5.0
Fig. 10.18 Square nut
m
d
s
e
Wing nuts
Figure 10.20 shows the dimensions of preferred sizes
of wing nuts manufactured in brass or malleable iron
by a hot stamping or casting process.
m
s
e
d
Fig. 10.19 Hexagon nut
Fig. 10.20 (Sizes are in Table 16.13)
E
G
D
F
Thread
size
Alternative
wing shape
A
H
J
B
C
Small rad
in corner
Table 10.13
Thread size A B C D E F G H J
M3 9 6.5 7 13.5 22 19 3.5 2.5 1.5
M4 and M5 10 8 9 15 25.5 19 4 2.5 1.5
M6 13 9.5 11 18 30 19 5 2.5 1.5
M8 16 12 13 23 38 19 6.5 3 2.5
M10 17.5 14 14 25.5 44.5 19 7 5 3
M12 19 16 15 28.5 51 25.5 8 5 3
M16 25.5 20.5 19 36.5 63.5 32 10 6.5 5
An alternative wing nut is available in brass or
malleable iron and manufactured by cold forging.MCE3 9M’3 4Machine3 Drawing73 Lectures3 by3 Kilanko3 OP 80