Page 459 - Hartner

Tapping size holes for thread cutting

UNF threads BSW (Whitworth) (Whitworth) threads Steel armoured conduit threads
ASME B1.1 threads BS84 (DIN-ISO 228-1) to DIN 40430
nom. threads tapping core diameter nom. threads tapping core diameter nom. threads tapping core diameter nom. threads tapping core diameter
Ø size of int. thread 2B Ø size of int. thread Ø size of int. thread Ø size of int. thread
hole Ø hole Ø hole Ø hole Ø
per DIN 336 min. max. per DIN 336 min. max. per DIN 336 min. max. per DIN 336 min. max.
inch mm mm mm inch inch mm mm mm inch inch mm mm mm inch mm mm mm
Nr. 1 - 72 1.55 1.473 1.610 W 1 / 16 60 1.20 1.045 1.230 G 1 / 16 28 6.80 6.561 6.843 Pg 7 20 11.40 11.280 11.430
Nr. 2 - 64 1.85 1.755 1.910 W 3 / 32 48 1.80 1.704 1.912 G 1 / 8 28 8.80 8.566 8.848 Pg 9 18 14.00 13.860 14.010
Nr. 3 - 56 2.15 2.024 2.197 W 1 / 8 40 2.50 2.362 2.591 G 1 / 4 19 11.80 11.445 11.890 Pg 11 18 17.30 17.260 17.410
Nr. 4 - 48 2.40 2.271 2.459 W 5 / 32 32 3.20 2.952 3.214 G 3 / 8 19 15.25 14.950 15.395 Pg 13.5 18 19.00 19.060 19.210
Nr. 5 - 44 2.70 2.550 2.741 W 3 / 16 24 3.60 3.407 3.745 G 1 / 2 14 19.00 18.631 19.172 Pg 16 18 21.30 21.160 21.310
Nr. 6 - 40 2.95 2.819 3.023 W 7 / 32 24 4.50 4.201 4.539 G 5 / 8 14 21.00 20.587 21.128 Pg 21 16 26.90 26.780 27.030
Nr. 8 - 36 3.50 3.404 3.607 W 1 / 4 20 5.10 4.724 5.156 G 3 / 4 14 24.50 24.117 24.658 Pg 29 16 35.50 35.480 35.730
Nr. 10 - 32 4.10 3.962 4.166 W 5 / 16 18 6.50 6.130 6.590 G 7 / 8 14 28.25 27.877 28.418 Pg 36 16 45.50 45.480 45.730
Nr. 12 - 28 4.60 4.496 4.724 W 3 / 8 16 7.90 7.492 7.987 G 1 11 30.75 30.291 30.931 Pg 42 16 52.50 52.480 52.730
1 / 4 - 28 5.50 5.359 5.588 W 7 / 16 14 9.20 8.789 9.330 G 1 1 / 8 11 35.50 34.939 35.579 Pg 48 16 57.80 57.780 58.030
5 / 16 - 24 6.90 6.782 7.036 W 1 / 2 12 10.50 9.989 10.591 G 1 1 / 4 11 39.50 38.952 39.592
3 / 8 - 24 8.50 8.382 8.636 W 9 / 16 12 12.00 11.577 12.179 G 1 1 / 2 11 45.25 44.845 45.485
7 / 16 - 20 9.90 9.728 10.033 W 5 / 8 11 13.50 12.918 13.558 G 1 3 / 4 11 51.00 50.788 51.428
1 / 2 - 20 11.50 11.328 11.608 W 3 / 4 10 16.25 15.797 16.483 G 2 11 57.00 56.656 57.296
9 / 16 - 18 12.90 12.751 13.081 W 7 / 8 9 19.25 18.611 19.353
5 / 8 - 18 14.50 14.351 14.681 W 1 8 22.00 21.334 22.147
3 / 4 - 16 17.50 17.323 17.678 W 1 1 / 8 7 24.50 23.928 24.832
7 / 8 - 14 20.40 20.269 20.650 W 1 1 / 4 7 27.75 27.103 28.007
1 - 12 23.25 23.114 23.571 W 1 3 /8 6 30.50 29.504 30.528
1 1 / 8 - 12 26.50 26.289 26.746 W 1 1 /2 6 33.50 32.679 33.703
1 1 / 4 - 12 29.50 29.464 29.921 W 1 5 / 8 5 35.50 34.769 35.963
1 3 /8 - 12 32.75 32.639 33.096 W 1 3 / 4 5 39.00 37.944 39.138
1 1 / 2 - 12 36.00 35.814 36.271 W 2 4.5 44.50 43.571 44.877

NPT ANSI B 2.1
American tapered pipe thread 1:16
Version A Version B nom. threads tapp. size hole Ø tapp. size hole Ø cutting depth cutting depth
(avoid if possible) Ø per cylindrical (A) conical (B) ET BT (min)
inch d1 D 1 mm mm
1 / 16 - 27 6.15 6.39 9.29 10.7
1 /8 - 27 8.40 8.74 9.32 10.8
1 / 4 - 18 11.10 11.36 13.52 15.6
3 / 8 - 18 14.30 14.80 13.83 16.0
1 / 2 - 14 17.90 18.32 18.07 20.8
3 /4 - 14 23.30 23.67 18.55 21.3
1 - 11.5 29.00 29.69 22.29 25.6
1 1 /4 - 11.5 37.70 38.45 22.80 26.1
1 1 / 2 - 11.5 43.70 44.52 22.80 26.1
2 - 11.5 55.60 56.56 23.20 26.5
2 1 /2 - 8 66.30 67.62 31.75 36.3
3 - 8 82.30 83.52 33.74 38.5

Metric/metric fine EG-threads (EG M14 x 1.25) UNC (UNC-STI) EG-threads UNF (UNF-STI) EG-threads
for wire thread inserts DIN 8140 for wire thread inserts ASME B18.29.1 for wire thread inserts ASME B18.29.1
nom. x pitch tapping core diameter nom. threads tapping core diameter nom. threads tapping core diameter
Ø P size of int. thread Ø size of int. thread Ø size of int. thread
hole Ø hole Ø hole Ø
DIN 336 min. max. per DIN 336 min. max. per DIN 336 min. max.
mm mm mm mm inch mm mm mm inch mm mm mm
EG M 4 0.70 4.20 4.152 4.292 EG Nr. 6 - 32 3.80 3.678 3.879 EG Nr. 6 - 40 3.70 3.644 3.818
EG M 5 0.80 5.25 5.174 5.334 EG Nr. 8 - 32 4.40 4.338 4.524 EG Nr. 8 - 36 4.40 4.321 4.498
EG M 6 1.00 6.30 6.217 6.407 EG Nr. 10 - 24 5.20 5.055 5.283 EG Nr. 10 - 32 5.10 4.999 5.184
EG M 8 1.25 8.40 8.271 8.483 EG Nr. 12 - 24 5.80 5.715 5.944 EG Nr. 12 - 28 5.70 5.682 5.809
EG M10 1.50 10.50 10.324 10.560 EG 1 / 4 - 20 6.70 6.624 6.868 EG 1 /4 - 28 6.60 6.546 6.721
EG M12 1.75 12.50 12.379 12.644 EG 5 / 16 - 18 8.40 8.242 8.489 EG 5 / 16 - 24 8.25 8.166 8.352
EG M14 x 1.25 14.40 14.271 14.483 EG 3 / 8 - 16 10.00 9.868 10.127 EG 3 / 8 - 24 9.80 9.754 9.931
EG M16 2.00 16.50 16.433 16.733 EG 7 / 16 - 14 11.60 11.506 11.783 EG 7 / 16 - 20 11.50 11.389 11.585
EG 1 / 2 - 13 13.30 13.122 13.393 EG 1 / 2 - 20 13.10 12.974 13.172
EG 9 /16 - 12 14.90 14.747 15.032 EG 9 / 16 - 18 14.70 14.592 14.798
EG 5 / 8 - 11 16.50 16.375 16.673 EG 5 / 8 - 18 16.25 16.180 16.386

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