Nuts, bolts, screws and washers

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 16.1(a) shows the bolt proportions and Table 16.1 the dimensions for bolts in common use. Dimensions of suitable nuts are also given and illustrated in Fig. 16.1(b). Included in Table 16.1 and shown in Fig. 16.1(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 16.1 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. 

Manual of

Engineering Drawing

Second edition

Colin H Simmons

I.Eng, FIED, Mem ASME.

Engineering Standards Consultant

Member of BS. & ISO Committees dealing with

Technical Product Documentation specifications

Formerly Standards Engineer, Lucas CAV.

Dennis E Maguire

CEng. MIMechE, Mem ASME, R.Eng.Des, MIED

Design Consultant

Formerly Senior Lecturer, Mechanical and

Production Engineering Department, Southall College

of Technology

City & Guilds International Chief Examiner in

Engineering Drawing
 

Geometric Tolerancing

Geometric Tolerancing is used to specify the shape of features.

Things like:

•Straightness

•Flatness

•Circularity

•Cylindricity

•Angularity

•Profiles

•Perpendicularity

•Parallelism

•Concentricity

•And More...

Geometric Tolerances are shown on a drawing with a feature control frame.

The Feature Control Frame

This feature control frame is read as: “The specified feature must lie perpendicular within a

tolerance zone of 0.05 diameter at the maximum material condition, with respect to datum

axis C. In other words, this places a limit on the amount of variation in perpendicularity

between the feature axis and the datum axis. In a drawing, this feature control frame would

accompany dimensional tolerances that control the feature size and position.

Principles of Engineering Drawing

Thayer Machine Shop

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SECTION 3 SURFACE TEXTURE

3.1 SCOPE OF SECTION This Section provides information on the indication of surface texture on

mechanical engineeringdrawingsandsimilar applications.For a more complete understandingof surface

texture, reference should be made to AS 2536.

3.2 SYMBOLS

3.2.1 Basic symbol The basic symbol is shown in Figure 3.1. The dimensions of surface texture

symbols are shown in Figure 3.2. Sloping lines in the symbol are at 60° to the horizontal.

3.2.2 Modification to basic symbol The following modifications may be made to the basic symbol:

(a) The symbol to be used where machining is mandatory shall be the basic symbol with a bar

added, as shown in Figure 3.3.

This symbol may be used alone to indicate that a surface is to be machined without defining

either the surface texture or the process to be used.

(b) The symbol to be used when the removal of material is not permitted shall be the basic symbol

with a circle added, as shown in Figure 3.4. This symbol may be used alone to indicate that a

surface is to be left in the state resulting from a preceding manufacturing process.

3.2.3 Extension of symbols When special surface characteristics are to be indicated (see Clause

3.4), the symbols shown in Figures 3.1, 3.3 and 3.4 may be extended by adding a line of appropriate

length to the long leg, as shown in Figure 3.5.

Australian Standard

Technical drawing

Part 201: Mechanical engineering drawing

Accessed by WOODSIDE ENERGY LTD on 21 Nov 2001

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The application of welding symbols to working drawings

The following notes are meant as a guide to the method

of applying the more commonly used welding symbols

relating to the simpler types of welded joints on

engineering drawings. Where complex joints involve

multiple welds it is often easier to detail such constructions

on separate drawing sheets.

Each type of weld is characterized by a symbol

given in Table 26.1 Note that the symbol is representative

of the shape of the weld, or the edge preparation, but

does not indicate any particular welding process and

does not specify either the number of runs to be deposited

or whether or not a root gap or backing material is

to be used. These details would be provided on a welding

procedure schedule for the particular job.

It may be necessary to specify the shape of the weld

surface on the drawing as flat, convex or concave and

a supplementary symbol, shown in Table 26.2, is then

added to the elementary symbol. An example of each

type of weld surface application is given in Table 26.3.

A joint may also be made with one type of weld on

a particular surface and another type of weld on the

back and in this case elementary symbols representing

each type of weld used are added together. The last

example in Table 26.3 shows a single-V butt weld

with a backing run where both surfaces are required to

have a flat finish.

A welding symbol is applied to a drawing by using

a reference line and an arrow line as shown in Fig.

26.1. The reference line should be drawn parallel to

the bottom edge of the drawing sheet and the arrow

line forms an angle with the reference line. The side of

the joint nearer the arrow head is known as the ‘arrow

side’ and the remote side as the ‘other side’.

The welding symbol should be positioned on the

reference line as indicated in Table 26.4.

Sketch (a) shows the symbol for a single-V butt

weld below the reference line because the external

surface of the weld is on the arrow side of the joint.

Sketch (b) shows the same symbol above the

reference line because the external surface of the weld

is on the other side of the joint.

Manual of

Engineering Drawing

Second edition

Colin H Simmons

I.Eng, FIED, Mem ASME.

Engineering Standards Consultant

Member of BS. & ISO Committees dealing with

Technical Product Documentation specifications

Formerly Standards Engineer, Lucas CAV.

Dennis E Maguire

CEng. MIMechE, Mem ASME, R.Eng.Des, MIED

Design Consultant

Formerly Senior Lecturer, Mechanical and

Production Engineering Department, Southall College

of Technology

City & Guilds International Chief Examiner in

Engineering Drawing

Elsevier Newnes

Linacre House, Jordan Hill, Oxford OX2 8DP

200 Wheeler Road, Burlington MA 01803

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