Solid Threading Endmills for Internal Thread Solid Threading Endmills for Internal Thread . W 55 ° WHIT WORTH ( BSW BSF, BSP, BSB ) BSPT 55 ° BRITISH STANDARD PIPE ap ap P P «— ft D dh6 D dh6 * 15 * ^ 15 L ^ L R0.137P Screw •Application: General engineering •Application : General engineering fittings and pipe couplings fittings and pipe couplings Dimension ( mm ) Dimension ( mm ) Designation TPI BSP No . of flutes Designation TPI BSP No . of flutes d D ap L d D ap L SMT 0606 C 9 28 W 28 G1/ 8 6 6.0 9.5 58 3 SMT 0606 C 9 28 BSPT 28 RC 1 / 8 6 6.0 9.5 58 3 0808 C 14 19 W 19 G1 / 4- 3 / 8 8 8.0 14.0 64 3 0808 C 14 19 BSPT 19 RC 1 / 4 - 3 / 8 8 8.0 14.0 64 3 1212 D 1914 W 14 G1 / 2 - 7 / 8 12 12.0 19.0 84 4 1212 D 19 14 BSPT 14 RC 1 / 2 - 7 / 8 12 12.0 19.1 84 4 1212 D 2614 W 14 G1 / 2 - 7 / 8 12 12.0 26.3 84 4 1616 D 28 11 BSPT 11 RC 1 - 2 16 16.0 28.9 105 4 1212 C 24 11 W 11 G 1-1 1 / 2 12 12.0 24.2 84 3 1616 D 38 11 W 11 G1- 3 16 16 , 0 38.1 105 4 2020 E47 11 W 11 G>1 20 20.0 47.3 105 5 101 102 NPT 60 ° NATIOANL PIPE ap P MAA/W ^ D dh6 * ^ 15 L 99 f Taper 1:16 Screw •Application: General engineering Dimension ( mm ) Designation TPI BSP No . of flutes d D ap L SMT 0606 C 9 27 NPT 27 1/8 6 6.0 9.9 58 3 0808 C 14 18 NPT 18 1/ 4 - 3 / 8 8 8.0 14.8 64 3 1212 D 20 14 NPT 14 1 / 2-3 / 4 12 12.0 20.9 84 4 1616 D 27 11.5 NPT 11.5 1- 2 16 16.0 27 , 6 105 4 2020 D 39 8 NPT 8 >2 1 / 2 20 20.0 39.7 105 4