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British Standard Brass (B.S.B.)

Thread Form

BSB Thread Form
  • p = Pitch = 1/TPI
  • h = Basic Depth of Thread = 0.640327p
  • r = Basic Radius = 0.137329p

Thread Tables

Nominal Diameter T.P.I Basic Depth of Thread Basic Major Diameter Basic Effective Diameter Basic Minor Diameter Tapping Drill Clearing Drill
(inch) (n/a) (inch) (inch) (inch) (inch) (mm) (mm)
1/8 26 0.0246 0.125 0.102 0.0757 2 3.3
1/4 26 0.0246 0.25 0.2254 0.2007 5.2 6.5
3/8 26 0.0246 0.375 0.3504 0.3257 8.5 9.7
1/2 26 0.0246 0.5 0.4754 0.4507 11.6 13
5/8 26 0.0246 0.625 0.6004 0.5657 14.75 16.25
3/4 26 0.0246 0.75 0.7254 0.7007 18 19.25
7/8 26 0.0246 0.875 0.8504 0.8257 21.25 22.5
1 26 0.0246 1 0.9754 0.9507 24.25 25.75
1,1/8 26 0.0246 1.125 1.1004 1.0757 27.5 29
1,1/4 26 0.0246 1.25 1.2254 1.2007 30.75 32
1,1/2 26 0.0246 1.5 1.4754 1.4507 37 38.5
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Last modified: SolFlu  Sun, 26 Jul 2009 06:11:35 GMT