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British Standard Cycle (B.S.C.)

Thread Form

BSC Thread Form
  • p = Pitch = 1/TPI
  • h = Basic Depth of Thread = 0.5327p
  • r = Basic Radius = 0.166p

Thread Tables

Nominal Size T.P.I. Basic Thread Depth Basic Major Diameter Basic Effective Diameter Basic Minor Diameter Tapping Drill Clearing Drill
(inch) (n/a) (inch) (inch) (inch) (inch) (mm) (mm)
1/8 40 0.0133 0.125 0.1117 0.0984 2.5 3.3
5/32 32 0.0166 0.1563 0.1397 0.1231 3.25 4.1
3/16 32 0.0166 0.1875 0.17085 0.1542 3.97 4.9
1/4 26 0.0205 0.25 0.22955 0.2091 5.56 6.5
9/32 26 0.0205 0.281 0.26065 0.2403 6.2 7.3
5/16 26 0.0205 0.3125 0.292 0.2715 7 8.1
3/8 26 0.0205 0.375 0.3545 0.334 8.65 9.7
7/16 26 0.0205 0.4375 0.417 0.3965 10.1 11.3
1/2 26 0.0205 0.5 0.4795 0.459 11.7 13
9/16 26 0.0205 0.5625 0.542 0.5215 13.1 14.5
5/8 26 0.0205 0.625 0.6045 0.584 15 16.25
11/16 26 0.0205 0.6875 0.667 0.6465 16.5 17.75
1 26 0.0205 1 0.9795 0.959 24.61 25.75
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Last modified: SolFlu  Sun, 26 Jul 2009 06:11:35 GMT