Whitworth Form Threads (55 Deg Thread Angle) |
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| Thread Form Data | Tapping Drill | Clearance Drill | |||||||
| Diameter | O/Diameter | Core | Pitch | Depth | Radius | Effective Dia | T.P.I | Dec / Met / Frac | Dec / Met / Frac |
| 1/8" | 0.1250 | 0.0930 | 0.0250 | 0.0160 | 0.0034 | 0.1090 | 40 | 0.1004 - 2.55mm | 0.1299 - 3.30mm |
| 3/16" | 0.1875 | 0.1341 | 0.0417 | 0.0267 | 0.0057 | 0.1608 | 24 | 0.1457 - 3.70mm | 0.1968 - 5.00mm |
| 1/4" | 0.2500 | 0.1860 | 0.0500 | 0.0320 | 0.0069 | 0.2180 | 20 | 0.2008 - 5.10mm | 0.2559 - 6.50mm |
| 5/16" | 0.3125 | 0.2414 | 0.0556 | 0.0076 | 0.0076 | 0.2769 | 18 | 0.2559 - 6.50mm | 0.3150 - 8.00mm |
| 3/8" | 0.3750 | 0.2950 | 0.0625 | 0.0400 | 0.0086 | 0.3350 | 16 | 0.3125 - 5/16" | 0.3858 - 9.80mm |
| 7/16" | 0.4375 | 0.3460 | 0.0714 | 0.0457 | 0.0098 | 0.3918 | 14 | 0.3642 - 9.25mm | 0.4531 - 29/64" |
| 1/2" | 0.5000 | 0.3933 | 0.0833 | 0.0534 | 0.0114 | 0.4466 | 12 | 0.4134 - 10.50mm | 0.5156 - 33/64" |
| 9/16" | 0.5625 | 0.4558 | 0.0833 | 0.0534 | 0.0114 | 0.5091 | 12 | 0.4764 - 12.10mm | 0.5781 - 37/64" |
| 5/8" | 0.6250 | 0.5086 | 0.0909 | 0.0582 | 0.0125 | 0.5668 | 11 | 0.5315 - 13.50mm | 0.6406 - 41/64" |
| 3/4" | 0.7500 | 0.6219 | 0.1000 | 0.0640 | 0.0137 | 0.6860 | 10 | 0.6406 - 41/64" | 0.7656 - 49/64" |
| 7/8" | 0.8750 | 0.7327 | 0.1111 | 0.0711 | 0.0153 | 0.8039 | 9 | 0.7579 - 19.25mm | 0.8906 - 57/64" |
| 1" | 1.0000 | 0.8399 | 0.1250 | 0.0800 | 0.0172 | 0.9200 | 8 | 0.8661 - 22.00mm | 1.0156 - 1-1/64" |
| 1-1/8" | 1.1250 | 0.9420 | 0.1429 | 0.0915 | 0.0196 | 1.0335 | 7 | 0.9744 - 24.75mm | 1.1405 - 1-9/64" |
| 1-1/4" | 1.2500 | 1.0670 | 0.1429 | 0.0915 | 0.0196 | 1.1585 | 7 | 1.0938 - 1-3/32" | 1.2656 - 1-17/64" |
| 1-1/2" | 1.5000 | 1.2866 | 0.1667 | 0.1067 | 0.0229 | 1.3933 | 6 | 1.3189 - 33.50mm | 1.5156 - 1-33/64" |
| 1-3/4" | 1.7500 | 1.4939 | 0.2000 | 0.1281 | 0.0275 | 1.6219 | 5 | 1.5354 - 39.00mm | 1.8906 - 1-57/64" |
| 2" | 2.0000 | 1.7154 | 0.2222 | 0.1423 | 0.0305 | 1.8577 | 4½ | 1.7520 - 44.50mm | 2.0156 - 2-1/64" |