BS308:Part1:1984
UDC 741.05:62:003.63 (Reprinted incorporatingAmendments No. 1 No. 2 and No. 31
Engineering drawingpractice
Part 1.Remendations for general principles
Pratique du dessin industrielPartie 1. Principes generaux
Technische ZeichnungenTeil 1. Aligemeine Grundsatze
Contents
Foreword Page 2Committees responsible Back cover
17 Patterns of repeated features Page 1819Economy in showing patters 18 Locating repeated features 1820 Cutting lane not indicated 19 1921 Cutting plane indicated 22 Examples of orientation of hatching 20 1923 Hatching of separated areas and adjacent parts 24Hacching of large areas 20 2026 Section through thin material 25 Subordination of hatching 21 2127 Wieb in longituinal section 21 2128 Spokes in longitudinal section 29 Assembly of pin lever and shaft 2130 Harf section 31 Local section 22 2232 Revolved sections 33 Removed sections 22 2335 Section in paralel planes 34 Successive sections 24 2537 Section in contigupus planes 36 Examples of section in intersecting planes 25 263B Item references 39 Adjaceot part 2640Imaginary ntersestion lines 28 2842 Indication fflat fetures ona shatt 41 Deveioped views 28 2943 Examples of knurling 44 Splinws 2945 Serrations 46 Conventions for screw threads 31 3147 Conventions for asembied screw threads 48 Conventions for wire thread inserts 3249Convention forrolling bearing 32 EE50 Gears: showing conventions for contours edges. pitch lines and circles 3351 Gears and rack: showing conventions for root surface 3452 Examples of use of symbols for gear teeth 3554 Extenengagement ofcylindrical gcars 53Assembled mating gears systems 9C55Internal angagementofcylindrical gars 36 3757Enggeenfgaxinretin 56 Engagement of pinion with rack 3758Engagementof whee withcylindrical worm any angle 36 3860 Compression springs 59 Chain wheels 39 4061 Tension springs 62 Torsion springs 41 4163 Cup springs 4264 Leaf springs 65 Spiral springr 42 43
Remendations
1Scope 2 Types of drawings in mon use 44 Scees 3 Drewing sheets 7 45 Lines 6 Letrering 77Projection 11 138Views 9 Sections and sectional views 15 1910 1tem references 11 Symbols and abbreviations 26 2712 Conventional regresentations 13 Marking 28 43
Appendix
A.Aspects of engineering drawing practice coveredby British and international IISOI standards 44
45
Index
Tables
2Types of line 1Remended drawing sheet sizes itrimrmed3 Character height 4. Symbols for gear teeth systerns
Figures
1 Drawing sheets showing frame title block and se 2 Applications of the various types of line 3 Priorities of coinciding lines5 Examples o1. letters and numerals 4 Leader lines6 Symbols indicating method of projection 7 Exampie ot first angle projection8 Example of third angle projection10 Exemple of a partial view projected from a full 9 Special arrangement of views11 Auxiliary view showing true shape of inclined view12 Enlarged features surface13 Representation of symmetrical parts 14 Representation of symmetrical parts with15 Methods ot indicating an interrupted view asymmetrical features added16 Repeated parts and features
Foreword
the direction of the Mechanical Engineering Standards This revis ion of BS 308 : Part 1 has been prepared underTakes account of both national and international develep- Committee; at refiects the established conventions and also1ments since the 1972 revision which is now withdrawn
drawing now enables its recognition as the graphical The proven record of standards applisd to engineeringlanguage of munication in engineering both nationall y and internationally. Orawings made to the acceptedstandards in one country when based on standards published by the international OrganiZation fgr Standardization (iSO) are understood and can be used around the world in virtually all countries With this in mind it was recognizedand accepted to be important as a policy for this revisionthat particutar attention and care should be paid to the quality ot content of both text and figures to cngure theirclarity and ease of understanding.
The UK continues to participate activgly in ISO TechnicalCommittes on technical drawing for the establishment of international published standards and much of thiecontenis of this standard reflects those ayreements reachednotes appear in this standard to draw attention to occasional internationally with which the UK has concurred. Some1divergence ol poracticc Appenuix A provides information gn aspeets of engineering drawing practice covered byBritish anc nternational stsndards.
The remendations of this standard have been establishedhaving regard to the requirements of microfiming. Drawingsfor microfilming and reducedsize reproduction techniques. ageins aq pinous puepuessti a suepuooo u pauedaad
Ouring tihe course cf this revision particutar attention has been paid to developiments in puter aicied machinedraughting oed st has Deon cstablished tat such machrines are currently capzble of oomplying with this standarc. Anyminor exceptons due to the limitations of s particularSystem would not be expected so μprejudice the under- standing of a drawing otherwise claimed to ply withIthis standard.
The 1972 revisson was coincidentally undertaken during themain period of transition of UK industry to the metric1units was inciuclod but this has not been retained in the present revision system and a limited recognition of the imperial system of
In the ISO Technical Commitee for technical drawing it isthe intention to unify in one set of standards the practices and oonventions of all disciplines using technical drawings.The ISO standards currently under revision atempt to reflect this policy. 1n the UK the traditional separations aremaintained and it should be carefully noted that BS 308drawings in the nanufacturing industries associaed continues to provide remendations for engineeringwith mechanieal electricat ectronics ydraulics.
pneumatics and nuclear engineeing disciplines as previousl.The requircments of the building architectural Civsl and
structural engincering and construction services industries continue to be covered by BS 1192. BS 308 does not coveraeronauticai lofting. There are stancards publishec for some special disciplines such as in naval architecture andincustries using BS308as abasis but requiring additional rernendations and conventions particutar to thepreparation of draings for optical elements and systems discipfine BS 4301 which gives remendations for theand BS 2774 which gives drawing conventions forlaboratory glassiware are examples
BS 5070 dealing with engineering diagram drawing practice industries providing remendations on a wide variety of is a panion stanrlard to BS 308 and caters for the sameengineering diagrams. Commonly as a diagram can becalled adrwing and a drwing can be called adigrm' it is useful to summarize the differenoe in the scopesacopted to be rawings tht define shape size and form of these stanclards. BS 30B covers what are coemmonlyflow of one sort or another and which relate ponents BS 5070 covers dliagrams that are normally associated withby the use of lines but do not depict their shape size or (usuall y indicated by symbols) functionaly one to anotherform; neither may they in general indicate actual connectionsor locations
For convenience of use thes revision of BS 308 follows theprecedent established in 1972 of publishing in Parts
Tis Part dals with eneral principles; it eads throughfrom the choice of paper sizes and scales to pleedismensions tolerances and related inforemation drawing of views and sections awaiting the application of
following international standards. The remendations are generally in accordance with the
ISO 128-1982 Technical drawings General principlesISO 2162-1973 Technical drawings Representation of presentationof springsISO 2203-1973 Technical drawings Conventional representation of gears ISO 3098-1974 Tochnical drawings Lettering Part 1. Currently used charactersISO 5455-1979 Technical drawings ScalesISO Technical drawings Sizes and layout of drawing sheetsISO 6410-1981Technical drawings ConventionalISO 6433-1981Technical drswings - Item references representation of threaded parts
Part 2 of this standard deals with dimensioning tolerancingsymbols. Part 3 of this standard deais specifically with and interpretations and the application ot surface roughnessgeometrical tolerancing.
Compliance with a British Standard does not of itself confer immunity from legal obtigations.
Notes on the presentation of this standard
NOTE 1. The figures i this standard are independent andeachisselected solely for its simlicityand clarity to ilustrate only the text to which it relates.Thev are notthe only possible examoles and they are not intended as design examples or to be fully dirmensionedbasic remencations of this standard.
working drwing buttherwiseare drwn acording to th
NOTE 2 Linear dimensions shown in the figures are inmillienetres.
NOTE 3. in the illustrations to this stancard conventionappear as part of the drawing and lower case letters are used is adopted of using capital letters for notes that wouldor notes explaining the point under consideration inrelation to the text.
NOTE 4 7his standard recognizes both the first and thirdas does ISO1281982.The first angle projection method s angle projection methods as having equal status see clause 7.that normally used for British Standards and is thus usedinpresentation. The third angle method is only shown where this publication in the interests of uniformity ofitillustrates th relevant clauseHowever it should be understood that the altermative projection method i.e. thirdangl projetioncouldqually wellhavebeenused without prejudice to the principies established.
NOTE 5. It is recognized in 9.3.1 that it is mon forhatching to be omitted where the time and expense involved sot justified and the understanding of the drawings wilnot be ipairedHatching is used throughout ths publication as nocmal practice in British Stancards.
NOTE 6 Due to the limitations of size of the figures in thisstandard the sizes of arrowheads may not conform to 5.4.
