Machinery's Handbook, 31st Edition
2710
Sheet Metal Gages Table 5a. Decimal Equivalent of Numbered Drill Sizes
Decimal
Decimal
Decimal
Decimal
Drill Number
Drill Number
Drill Number
Drill Number
Inch mm
Inch mm
Inch mm
Inch mm
1 0.2280 5.791 26 0.1470 3.734 51 0.0670 1.702 76 0.0200 0.508 2 0.2210 5.613 27 0.1440 3.658 52 0.0635 1.613 77 0.0180 0.457 3 0.2130 5.410 28 0.1405 3.569 53 0.0595 1.511 78 0.0160 0.406 4 0.2090 5.309 29 0.1360 3.454 54 0.0550 1.397 79 0.0145 0.368 5 0.2055 5.220 30 0.1285 3.264 55 0.0520 1.321 80 0.0135 0.343 6 0.2040 5.182 31 0.1200 3.048 56 0.0465 1.181 81 0.0130 0.330 7 0.2010 5.105 32 0.1160 2.946 57 0.0430 1.092 82 0.0125 0.318 8 0.1990 5.054 33 0.1130 2.870 58 0.0420 1.067 83 0.0120 0.305 9 0.1960 4.978 34 0.1110 2.819 59 0.0410 1.041 84 0.0115 0.292 10 0.1935 4.915 35 0.1100 2.794 60 0.0400 1.016 85 0.0110 0.280 11 0.1910 4.851 36 0.1065 2.705 61 0.0390 0.991 86 0.0105 0.267 12 0.1890 4.800 37 0.1040 2.642 62 0.0380 0.965 87 0.0100 0.254 13 0.1850 4.700 38 0.1015 2.578 63 0.0370 0.940 88 0.0095 0.241 14 0.1820 4.623 39 0.0995 2.527 64 0.0360 0.914 89 0.0091 0.231 15 0.1800 4.572 40 0.0980 2.489 65 0.0350 0.889 90 0.0087 0.221 16 0.1770 4.496 41 0.0960 2.438 66 0.0330 0.838 91 0.0083 0.211 17 0.1730 4.394 42 0.0935 2.375 67 0.0320 0.813 92 0.0079 0.200 18 0.1695 4.305 43 0.0890 2.261 68 0.0310 0.787 93 0.0075 0.190 19 0.1660 4.216 44 0.0860 2.184 69 0.0292 0.742 94 0.0071 0.180 20 0.1610 4.089 45 0.0820 2.083 70 0.0280 0.711 95 0.0067 0.170 21 0.1590 4.039 46 0.0810 2.057 71 0.0260 0.660 96 0.0063 0.160 22 0.1570 3.988 47 0.0785 1.994 72 0.0250 0.635 97 0.0059 0.150 23 0.1540 3.912 48 0.0760 1.930 73 0.0240 0.610 … … … 24 0.1520 3.861 49 0.0730 1.854 74 0.0225 0.572 … … … 25 0.1495 3.797 50 0.0700 1.778 75 0.0210 0.533 … … … Table 5b. Decimal Equivalent of Letter Drill Sizes Inch mm A 0.234 5.944 G 0.261 6.629 M 0.295 7.493 S 0.348 8.839 Y 0.404 10.262 B 0.238 6.045 H 0.266 6.756 N 0.302 7.671 T 0.358 9.093 Z 0.413 10.490 C 0.242 6.147 I 0.272 6.909 O 0.316 8.026 U 0.368 9.347 … … … Decimal Drill Size Decimal Drill Size Decimal Drill Size Decimal Drill Size Decimal Inch mm Inch mm Inch mm Inch mm D 0.246 6.248 J 0.277 7.036 P 0.323 8.204 V 0.377 9.576 … … … E 0.250 6.350 K 0.281 7.137 Q 0.332 8.433 W 0.386 9.804 … … … F 0.257 6.528 L 0.290 7.366 R 0.339 8.611 X 0.397 10.084 … … … Wire Drawing History.— Wire drawing is the process used for producing wire by draw ing a wire or rod of larger diameter through a plate or die provided with a hole which reduces the size to the desired dimension. Previous to wire drawing, wire was made by hammering or beating metal into thin sheets or plates, which were cut into continuous strips. These strips were then afterwards rounded by hammering. There is evidence that wire was produced by a simple hammering process as early as 2000 B.C., and perhaps earlier. The history of the art does not clearly indicate when simple hammering was super seded by the method of drawing through a die, but records are available to show that wire drawing on a commercial scale was practiced in France in 1270, in Germany in 1350, and in England in 1466. The first wire-drawing mill in America was built in 1775, in Norwich, Conn., by Nathaniel Niles, who was granted a loan of $1500 by the court for this purpose. Shaped Wire.— Shaped wire is any wire not round in section; it may be square, rectangu lar, hexagonal, triangular, half-round, oval, etc. Some sections of shaped wire may be either rolled or drawn. Shaped wire is a specialty, subject to agreement between purchaser and manufacturer as to size, finish, temper, and weight of coils and packages. Drill Size
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