
10. Tap Thread Limits (JIS, DIN, ANSI) Intro Unified Threads (UNC/UNF) Unit: mm Major Minor Major Minor Pitch Diameter Pitch Diameter Kind diameter diameter Kind diameter diameter SP Size of Class Upper Lower Tolerance Basic Size of Class Upper Lower Tolerance Basic tap Basic Basic Tolerance tap Basic Basic Tolerance Size Size (μm) + Tolerance Size Size (μm) + Tolerance (μm) + (μm) Size (μm) + (μm) Size P1 20 0 20 P1 20 0 20 P2 40 20 20 P2 40 20 20 SL P3 60 40 20 P3 60 40 20 cutting tap cutting tap 3B 25 11 14 3B 30 14 16 2B 4.826 4.310 40 18 22 3.967 1/4-20UNC 2B 6.350 5.524 46 22 24 4.976 2BX 60 38 22 2BX 71 47 24 PO GH2 25.4 12.7 12.7 GH2 25.4 12.7 12.7 GH3 38.1 25.4 12.7 GH3 38.1 25.4 12.7 No.10-32UNF GH4 50.8 38.1 12.7 GH5 63.5 50.8 12.7 3BX 51 38 13 3BX 64 51 13 2BX 64 51 13 2BX 76 64 12 ST forming tap forming tap G5 64 51 13 G6 76 64 12 1/4-20UNC 6.350 5.524 4.976 G6 4.826 4.310 76 64 12 3.967 G7 89 76 13 G7 89 76 13 H4 50.8 38.1 12.7 H4 50.8 38.1 12.7 H6 76.2 63.5 12.7 ROLL H6 76.2 63.5 12.7 P1 20 0 20 P1 20 0 20 P2 40 20 20 P2 40 20 20 P3 60 40 20 P3 60 40 20 3B 27 11 16 cutting tap CARBIDE 3B 28 12 16 2B 43 19 24 cutting tap 6.350 5.761 5.367 2B 43 20 23 2BX 63 39 24 5.486 4.798 4.341 2BX 63 40 23 GH2 25.4 12.7 12.7 GH2 25.4 12.7 12.7 GH3 38.1 25.4 12.7 1/4-28UNF LONG No.12-24UNC GH3 38.1 25.4 12.7 GH4 50.8 38.1 12.7 GH4 50.8 38.1 12.7 GH5 63.5 50.8 12.7 GH5 63.5 50.8 12.7 3BX 51 38 13 3BX 51 38 13 2BX 76 64 12 forming tap HAND forming tap 2BX 76 64 12 G6 76 64 12 TAPS G6 5.486 4.798 76 64 12 4.341 G7 6.350 5.761 89 76 13 5.367 H4 50.8 38.1 12.7 H4 50.8 38.1 12.7 H6 76.2 63.5 12.7 H6 76.2 63.5 12.7 P1 20 0 20 P2 40 20 20 EG (STI) P2 40 20 20 P3 60 40 20 P3 60 40 20 3B 32 14 18 cutting tap 3B 27 11 16 2B 49 23 26 cutting tap 7.938 7.021 6.411 SPECIAL 2B 42 19 23 2BX 74 48 26 THREADS, 2BX 5.486 4.897 62 39 23 4.503 GH2 25.4 12.7 12.7 GAUGES GH2 25.4 12.7 12.7 5/16-18UNC GH3 38.1 25.4 12.7 No.12-28UNF GH3 38.1 25.4 12.7 GH5 63.5 50.8 12.7 GH4 50.8 38.1 12.7 3BX 64 51 13 THREAD forming tap GH5 63.5 50.8 12.7 2BX 89 76 13 MILLS 3BX 51 38 13 G7 7.938 7.021 89 76 13 6.411 forming tap 2BX 76 64 12 H5 63.5 50.8 12.7 G6 5.486 4.897 76 64 12 4.503 H7 88.9 76.2 12.7 DIES H4 50.8 38.1 12.7 H6 76.2 63.5 12.7 CENTER DRILLS Technical info 676