Specificationfor
Unifiedmachinescrews andmachine screwnuts
Committeesresponsibleforthis British Standard
The preparation of this British Standard was entrusted by the GeneralMechanical Engineering StandardsPollcy Committee（GME/-）toTechnical Committee GME/9 upon which the following bodies were represented:
British Constructional Steelwork Association Ltd. BEAMA Ltd.British Industrial Fasteners FederationBritish Railways Board British Steel IndustryBritish Steel Industry (Wire Section) Gauge and Tool Makers'AssociationSocioty of Motor Manufacturers and Traders Limited Ministry of DefenceWasher Manufacturers'Assoclation of Great Britaln
The following bodles were also represented in the drafting of the standard through submittees and panels:
British Indepandent Steel Producers’ Association British Furniture Manufacturers'FederationNational Association of Fastener Stockholders
boen propared under the Thus British Standard havingdirection of the General Mechanical Engineeringwas pubitshed under the athority of the Standands Boend Standards Polley Committe 1651 snny 06 and es into effect on
Amendments issued since publication
DatoAmd. No.7485 19-143
The following BSI references relate to the work on thisCommittee referenee GMR/ standard:Draft for ment DC
6 06961 069 0 N891
Contents
Inside front cover PageCommittees responsible Foreword 4Specification1 2 Terminology Scope 58 Material 54 Heads of screws General dimensions 5 65 6 Screw threads 67 Nominal length of screws Length of thread on screws 6 68 9 Diameter of unthreaded shank on screws 710 Ends of screws Radius under the head of screws 7 712 11 Designation 9AppendicesA Dimensions of S0° countersunk head screws Standard sizes of machine screws 33 34Metric slot widths 39Tables 1 Under head radii 82 Header point dimensions for UNC serews 98 4 Header point dimonsions for UNF screws Slotted countersunk head machine screws 10 95 Recessed countersunk head machine screws: details of recess type Z 116 7 Slotted truncated countersunk head machine screws: short length Recessed truncated countersunk head machine screws: details of 12recesstype Z 188 9 Slotted ralsed countersunk head machine screws Recessed raised countersunk head machine screws: detafls of recess 1410 type Z Slotted truncated ralsed countersunk head machine screws: short 15length 1611 Recessed truncated raised countersunk head machine screws:details of recess type Z 1712 Slotted and recessed pan head machine screws 1813 14 Slotted ralsed cheese head machine screws Recessed pan head machine screws: details of recess type Z 19 02
15 Recessed ralsed cheese hend machine scrows: details of recess type Z Pagc16 Platm and slotted hexagon hond machine screws Symmotry and concentricity tolerances 22 2117 18 Nominal lengths and tolerances for machine screws 2319 Dimensions of machtne screwnuts:precision type sizes No.0to No.12 2420 Dimenslons of machine screw nuts: pressed type square and hexngon 26 2521 22 Recesed countersunk headmache screws:detalfrecestype Recesed truncated countersunk head machino screws: detalls of 28recess typeV 28Reccwed ratsed countersunk head machine screws: details of reccs od24 Recesed truncated raised contersunk headmachine screws: details ofrocess typeV 29Rocossed pan head machine screws: detalls of recess type V 08 31Recessed raised cheeseheadmachine screws:detailsofrecesstypV Standard stzes for countersunk head machine scrows: ISO inch 82(Unified) threads 34Standard sizes for raised countersunk hend machino screws: ISO inch (Unified) threads 35Standard sizes for pan head machine screws: ISO inch (Unified) threadsStandard sizee for raised cheese lheud machtne screws: ISO inch 36Standard sizes for hoxngon head machine screws: ISO Inch (Unified) (Unified) threads 37threads 88
2526 2728293031Metrie slot widths32 391 Rolled thread end 7Cut thread chamfered end Cut thread radiused end 7Cone pointed ends Header point 8 7Slotted countersunk headmachine screws 8Recessed countersunk head machine screws: enlarged views of rocess type Z 10Slotted truncated countersunk heati machtne screws 11 12Recesed truncated countersunk headmachine screws:onlarged views ofrocoe type ZSlotted raised countersunk head machine screws 13 14Reccsed raised countersunk head machine screws: enlargod viows of recess type Z 15
Figures
8 245
Page13 Recessed truncated raised countersunk head machine screws: 12 Slotted truncated countersunk head machine screws 16enlarged vlews ofrecess type Z Slotted and recessed pan head machine screws 17 1814 15 Recessed pan head machine screws: enlarged views of recess type Z 1916 Recessed raised cheese head machine screws: eniarged views of Slotted raised cheese head machine screws 2017 recoss type Z 2118 19 Plain and slotted hexagon head machine screws Symmetry and concentricity tolerances 22 2320 Machine screw nuts: precision type sizes No. 0 to No. 12 2521 22 Machine screw nuts: pressed type Recessed countersunk head machine screws: enlarged vlews of recess 26type V 2723 Recessed truncated countersunk headmachine screws:enlarged views of recess type V 2824 reoess typeV Recessed raised countersunk head machine screws: enlarged views of 2925 Recessed truncated raised countersunk head machine screws:26 enlarged views of recess type V Receseed pan hcad machine screws: enlarged views of recess type V 31 3027 Recessed raised cheese head machine screws: enlarged views of recess type V 3228 Size of countersunk screw head 3329 Edge of head of countersunk screw 83
