Thread Milling Tools UN (UNC, UNF, UNEF) INTERNAL ANSI B1.1 - 1982 UN NUT 1/4P 60 1/8P UN SCREW HELICAL FLUTES THREAD SIZE PITCH ORDERING L L1 D1 D2 NO. OF COARSE FINE EXTRA FINE TPI CODE FLUTES UNC UNF UNEF 1 5/16" 32 TMG06059L14 32UN 57 14.0 6 5.9 3 2 3/8" 32 TMG08079L18 32UN 63 18.0 8 7.9 3 3 1/4" 28 TMG06051L12 28UN 57 12.2 6 5.1 3 4 7/16"-1/2" 28 TMG08079L15 28UN 63 15.8 8 7.9 4 5 5/16" 24 TMG06059L10 24UN 57 10.8 6 5.9 3 6 3/8" 24 TMG08079L15 24UN 63 15.3 8 7.9 4 7 9/16" ,5/8" 24 TMG12119L22 24UN 84 22.7 12 11.9 4 8 1/4" 20 TMG06048L12 20UN 57 12.0 6 4.8 3 9 7/16" 20 TMG08079L19 20UN 63 19.7 8 7.9 3 10 1/2" 20 TMG10099L22 20UN 73 22.5 10 9.9 4 11 3/4"-1" 20 TMG12119L26 20UN 84 26.0 12 11.9 4 12 5/16" 18 TMG06057L16 18UN 57 16.0 6 5.7 3 13 9/16" ,5/8" 18 TMG10099L23 18UN 73 23.5 10 9.9 4 14 3/8" 16 TMG08068L18 16UN 63 18.2 8 6.8 3 15 3/4" 16 TMG12119L26 16UN 84 26.2 12 11.9 4 16 7/16" 14 TMG08078L20 14UN 63 20.8 8 7.8 3 17 7/8" 14 TMG12119L24 14UN 84 24.5 12 11.9 4 18 1/2" 13 TMG10093L24 13UN 73 24.4 10 9.3 3 19 9/16" 12 TMG12106L26 12UN 84 26.4 12 10.6 4 20 1" 12 TMG16159L39 12UN 105 39.1 16 15.9 5 21 5/8" 11 TMG12115L31 11UN 84 31.1 12 11.5 3 22 3/4" 10 TMG16143L36 10UN 105 36.8 16 14.3 4 23 7/8" 9 TMG16159L40 9UN 105 40.9 16 15.9 4 24 1" 8 TMG20197L42 8UN 105 42.8 20 19.7 4 7