1、BRITISH STANDARD CONFIRMED FEBRUARY1984 BS1978:1965 Incorporating Amendment No.1 Specification for Bit braces UDC674.055:621.951.56BS1978:1965 This BritishStandard, having been approved by the MechanicalEngineering IndustryStandards Committeeand endorsed bytheChairman of the Engineering Divisional C
2、ouncil,was published undertheauthority of theGeneralCouncil on 26November1965 BSI12-1999 First published May 1953 First revision November1965 The following BSI references relate to the work on this standard: Committee reference MTE/15 (formerly MEE/120 MEE/120/3) Draft for comment D64/8539 ISBN 0 58
3、0 34150 X Co-operating organizations The Mechanical Engineering Industry Standards Committee, under whose supervision this BritishStandard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Associated Offices Technical Com
4、mittee Institution of Heating and Ventilating Association of Consulting Engineers Engineers Association of Mining Electrical and Institution of Mechanical Engineers Mechanical Engineers Institution of Mechanical Engineers Board of Trade (Automobile Division) British Chemical Plant Manufacturers Inst
5、itution of Production Engineers* Association Locomotive and Allied Manufacturers British Compressed Air Society Association of Great Britain British Electrical and Allied Manufacturers London Transport Board* Association Machine Tool Trades Association* British Gear Manufacturers Association Ministr
6、y of Defence, Army Department* British Internal Combustion Engine Ministry of Defence, Navy Department* Manufacturers Association Ministry of Labour (H.M. Factory British Iron and Steel Federation Inspectorate) British Mechanical Engineering Federation* Ministry of Power British Railways Board* Mini
7、stry of Public Building and Works Crown Agents for Oversea Governments and Ministry of Technology National Administrations Engineering Laboratory Electricity Council, The Generating Board Ministry of Transport and the Area Boards in England and Wales National Coal Board* Engineering Equipment Users
8、Association National Physical Laboratory (Ministry of Gas Council* Technology) Institute of Marine Engineers Radio Industry Council Institution of Civil Engineers Royal Institute of British Architects Institution of Gas Engineers* The Government departments and scientific and industrial organization
9、s marked with an asterisk in the above list, together with the following, were directly represented on the committee entrusted with the preparation of this BritishStandard: Association of U.K. Plier Manufacturers Ministry of Aviation Manufacturers of Edge Tools National Association of Tool Dealers E
10、ngineers and Allied Hand Tool Makers National Union of Furniture Trade Association Operatives Federation of British Hand Tool Post Office Manufacturers Saw Trades Association Institution of Engineering Inspection Society of British Aerospace Companies Ltd. J.E.S.C. Sub-committee on Hand Tools Societ
11、y of Motor Manufacturers and Light Edge Tool and Allied Trades Traders Ltd. Association Co-opted manufacturers Amendments issued since publication Amd. No. Date of issue Comments 5973 July1989 Indicated by a sideline in the marginBS1978:1965 BSI 12-1999 i Contents Page Co-operating organizations Ins
12、ide front cover Foreword ii Section 1. General 1 Scope 1 2 Nomenclature and definitions 1 Section 2. Manufacture 3 Materials 6 4 Heat treatment and hardness 7 5 Jaws 7 6 Chuck and nose 7 7 Rack 8 8 Centre handle and head 8 9 Head sub-assembly 8 10 Dimensions, fits and accuracy 8 11 Finish 9 12 Marki
13、ng 9 13 Performance tests 9 Appendix A Head sub-assemblies 11 Appendix B Tables for conversion of inches to approximate millimetre equivalents 13 Figure 1 Nomenclature of Type1bit brace 4 Figure 2 Nomenclature of Type2bit brace 5 Figure 3 Sectional view of bit brace chuck with auger bit in position
14、showing annular clearance 10 Figure 4 Forms of head sub-assemblies 12BS1978:1965 ii BSI 12-1999 Foreword This standard makes reference to the following BritishStandards: BS309, Whiteheart malleable iron castings. BS310, Blackheart malleable iron castings. BS328, Twist drills and combined drills and
15、countersinks Part 1:Twist drills. BS427, Method for Vickers hardness test Part1: Testing of metals. BS970, Wrought steels. En series. BS1224, Electroplated coatings of nickel and chromium. BS1408, Patented cold drawn steel spring wire. BS2054, Augers and auger bits. BS2590, Acceptance tests for sint
16、ered metal powder components. BS2789, Iron castings with spheroidal or nodular graphite. This BritishStandard, which was first published in1953, has been revised under the authority of the Mechanical Engineering Industry Standards Committee. Therevision takes account of the latest manufacturing tech
17、niques including the use of chuck jaws manufactured by powder metallurgical methods. Apart from materials, heat treatment and hardness, the standard includes clauses on nomenclature, definitions, finish and the nominal size range of the bit braces. The quality of the tools is further ensured by the
18、inclusion of performance tests. Chuck jaws of the alligator pattern only are provided for in this BritishStandard. It is recognized that chucks are available which incorporate universal type jaws, but these are considered to be more specialized in their application than the alligator type. In any ca
19、se, such chucks are normally supplied as an integral part of a brace, designed to form a complete tool intended for some special purpose and for this reason details of such jaws, chucks or braces have been omitted from the standard. The Type2 brace, referred to in the Scope clause as a plain brace,
20、relates to those often known as the “wagon-builders brace” and the “linesmans brace”. Thedifferences between these two are so slight, being concerned with variations in the dimensions of the sweep and the materials forming the handles, as to render differentiation inadvisable in this BritishStandard
21、. The provisions which apply to the chucks and the jaws have been correlated with the dimensions of the round shank and square taper tangs of auger bits given in BS2054, “Augers and auger bits”, thus ensuring that the two will function together efficiently. Similarly the square taper tangs of bit st
22、ock twist drills conforming to BS328-1, “Twist drills”, are also accommodated. NOTEA table from which metric equivalents can be calculated is given in an appendix. The figures in British units are to be regarded as the standard. More accurate conversions should be based on the tables in BS350, “Conv
23、ersion factors and tables”. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pa
24、ges This document comprises a front cover, an inside front cover, pagesi andii, pages1 to13 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS1978:1965 BSI 12-1999
25、1 Section 1. General 1 Scope This BritishStandard relates to bit braces (sometimes referred to as carpenters braces), of the following types and nominal sizes: Type 1. Ratchet brace fitted with chuck (seeFigure 1) having a range of nominal sizes as follows:5in,8in,10in,12in and14in. Type 2. Plain br
26、ace, fitted with socket end (nose) which includes the types known as wagon-builders brace,14in nominal size and linesmans brace,9in nominal size (seeFigure 2). 2 Nomenclature and definitions For the purposes of this BritishStandard the following definitions apply: 2.1 bit brace a cranked hand tool d
27、esigned primarily for rotating auger bits and bit stock drills. SeeFigure 1 and Figure 2 2.2 sweep twice the throw of the crank of the frame. SeeFigure 1 and Figure 2 2.3 nominal size a value which is equal to the sweep see2.2 above 2.4 shell the outer component of the chuck which is threaded intern
28、ally to fit the screw end and formed externally for manual operation. The shell forms the outer housing for the hardened jaws and provides the means by which the jaws are caused to grip the tools. Three typical forms of shell are shown in Figure 1 2.5 jaws the components designed to fit into and be
29、operated by the shell, and intended to accommodate and grip the square taper tangs of bits and drills. Jaws are heat-treated; assembled in pairs and are for the purpose of giving an efficient grip on square taper tangs having dimensions within the limits given in Subclause6 a)ii). SeeFigure 1 2.6 ja
30、w spring the spring which secures the jaws together in pairs and provides the tension necessary for the opening action. SeeFigure 1 2.7 screw end the component threaded externally to accept the shell and designed to form the inner housing for the jaw assembly, the outer housing being formed by the s
31、hell. The screw end is fitted to the ratchet body sub-assembly. SeeFigure 1 2.8 knurled thrust washer the knurled washer which acts as a wearing pad between the screw end and the ratchet body. SeeFigure 1 2.9 Ratchet body sub-assembly (SeeFigure 1) A sub-assembly comprising the following components:
32、 2.9.1 rack the circular toothed member actuated by the pawls through which the torque is appliedBS1978:1965 2 BSI 12-1999 2.9.2 ratchet body the component designed to accommodate the screw end, rack, pawls and pawl spring 2.9.3 rack pin the pin used for securing the rack to the screw end 2.9.4 pawl
33、s the components controlled by the cam ring which actuate the rack 2.9.5 pawl spring the helical spring which ensures that the pawls engage in the rack 2.9.6 pawl pins the pins used to secure the pawls to the ratchet body 2.10 cam ring the component having an eccentric groove in the bore for selecti
34、ng the action of the pawls. It is knurled to provide for manual adjustment. SeeFigure 1 2.11 ratchet body to frame pin the pin securing the ratchet body to the frame. SeeFigure 1 2.12 cam stop pin the pin functioning as a positive stop during rotation of the cam ring. SeeFigure 1 2.13 Frame sub-asse
35、mbly (SeeFigure 1) A sub-assembly comprising the following components: 2.13.1 frame the cranked component carrying the centre handle on which the ratchet body and head sub-assemblies are mounted 2.13.2 centre handle the component set in the centre of the frame providing a freely revolving hand grip
36、for rotating the brace 2.13.3 handle collars the collars secured to the frame or handle which provide a correct location for the handle 2.14 ball cup the component attached to the end of the frame which provides both a bearing surface and a housing for the hardened balls. SeeFigure 1 and Figure 2 2.
37、15 hardened balls the balls designed to take the thrust of the head, identical to those used in ball bearings. SeeFigure 1 and Figure 2BS1978:1965 BSI 12-1999 3 2.16 ball thrust washer the retaining washer which provides a bearing surface and which acts as a thrust pad between the head sub-assembly
38、and the balls. SeeFigure 1 and Figure 2 2.17 Head sub-assembly (SeeFigure 1 and Figure 2) A sub-assembly comprising the following components: 2.17.1 quill disk the circular plate secured to the quill hub and formed to provide the housing for the head. SeeAppendix A and Figure 4 2.17.2 quill hub the
39、component fitting and revolving freely on the end of the frame, forming a mounting for the quill disk and head 2.17.3 quill washer a U-shaped or spring washer which secures the head sub-assembly to the frame 2.17.4 head the component through which pressure is applied to the tool 2.17.5 screws wood s
40、crews for attaching the quill disk to the head The following terms are applicable only to Type2bit braces (seeFigure 2): 2.18 nose to frame pin the pin which secures the nose to the frame 2.19 nose the component secured to the frame which has a square tapered hole for the receipt of auger bits, bit
41、stock drills,etc., the tangs of which are locked in position by the thumb screw provided in the nose 2.20 thumb screw the screw fitted in the nose for locking the bits or drills in positionBS 1978:1965 4 BSI 12-1999 Figure 1 Nomenclature of Type1bit braceBS 1978:1965 BSI 12-1999 5 Figure 2 Nomenclat
42、ure of Type2bit braceBS1978:1965 6 BSI 12-1999 Section 2. Manufacture 3 Materials The components of both Types1 and2bit braces shall be manufactured from the materials specified below: Components Materials a) Round, knurled shell (No.2,Figure 1) A suitable steel selected from BS970 a . Screw end Knu
43、rled thrust washer Rack pin Frame Handle collars Ball bearing cup Ball thrust washer Quill hub Cam stop pin Ratchet body to frame pin Quill disk Quill washer Nose to frame pin b) Jaws Malleable iron complying with BS309 bor BS310 c ; alternatively from a steel suitable for case-hardening selected fr
44、om BS970 aor from sintered steel having a tensile strength of not less than25tonf/in 2and a density of not less than7when determined in accordance with BS2590 d . c) Pawls Malleable iron complying with BS309 bor BS310 c ; alternatively from a steel suitable for case-hardening selected from BS970 a .
45、 d) Jaw spring Material complying with BS970 a , Pawl spring En49; alternatively from hard drawn wire complying with BS1408 e . e) Multi-sided straight shell (No.1,Figure 1) Malleable iron complying with BS309 bor BS310 c ; alternatively from a suitable steel selected from BS970 a . Multi-sided, rad
46、iused shell (No.3, Figure 1) Nose f) Pawl pin Material complying with BS970 a , En32A. g) Thumb screw Malleable iron complying with BS309 bor BS310 c , or from steel wire. When manufactured from steel wire, thumb screws shall have a tensile strength of not less than24tonf/in 2 h) Ratchet body Mallea
47、ble iron complying with BS309 bor BS310 c , or from material complying with BS970 a , En1A. j) Hardened balls From steel complying with BS970 aEn31 or similar steel as used in the manufacture of ball bearings. k) Centre handle Head Beech or rosewood, or by arrangement between purchaser and manufactu
48、rer from suitable plastics materials, with the exception of the centre handle on the type known as the wagon-builders brace which normally is manufactured from malleable iron complying with BS309 bor BS310 c . l) Rack Steel selected from BS970-1 or alternatively a suitable sintered iron alloy capabl
49、e of being plated. m) Cam ring Steel selected from BS970-1 or alternatively a plastic moulded acetyl resin component. NOTEWherever malleable iron to BS309 bor BS310 cis specified above a spheroidal graphite iron complying with BS2789 fmay be used as an alternative. a BS970 “Wrought steels,” En series. b BS309 “Whiteheart malleable iron castings.” c BS310 “Blackheart malleable iron castings.” d BS2590 “Sintered metal powder components.” e BS1408 “Hard drawn steel wire for springs.” f BS2789 “Iron castings with spheroidal or nodular graphite.”
