Sherwood NO.25 Gauge HSS S/S Jobber Drill- you get 5

Number Sizes Series J100 General purpose drills for steels, cast steel, grey cast iron, malleable cast iron, nickel brass, aluminium alloy and graphite. Point angle: 118, helix angle: normal, web thickness: standard, relief angle: 8 - 20, tolerance of diameter: h8, tolerance of shank: f11. Manufactured to ANSI B328, BS 328 and DIN 338. Number & Letter Gauge Drills Gauge drills are still in common use in the U.S. In the past, they were popular elsewhere, but now have been largely discarded in favour of metric sizes. When using a gauge rather than a standard measurement of size the user has to refer to a table of gauge sizes. For example, to drill a hole which is 10 thou (thousandth of an inch = .0010) bigger than a 1/8 inch bolt, the user must first work out that 1/8 inch is 125 thou, so the hole size needed is 135 thou, and then must look up in a reference book which gauge drill bit is closest to this diameter - a number 29. Number gauge sizes are similar or equivalent in some respects to, but different from, American wire gauge. Number gauge is usually used from size 80 (the smallest) to size 1 (the largest) followed by letter gauge size A (the smallest) to size Z (the largest). Number gauge is actually defined down to size 97, but these smaller sizes are rarely encountered. It happens that as the technology for making small drill bits and drilling small holes has become more available, metric drills have become the norm. The gauge-to-diameter conversion does not follow a set formula, but rather was defined as a useful and practical measure. The graph shows how gauge diameters change with gauge. Each step along the horizontal axis is one gauge size. The step size between adjacent gauges is smaller for smaller gauges. This is appropriate, because the tolerance of the diameter of drilled holes is closer for smaller drill bits. Gauge inch mm 80 0.014 0.343 79 0.015 0.368 78 0.016 0.406 77 0.018 0.457 76 0.020 0.508 75 0.021 0.533 74 0.023 0.572 73 0.024 0.610 72 0.025 0.635 71 0.026 0.660 70 0.028 0.711 69 0.029 0.742 68 0.031 0.787 67 0.032 0.813 66 0.033 0.838 65 0.035 0.889 64 0.036 0.914 63 0.037 0.940 62 0.038 0.965 61 0.039 0.991 60 0.040 1.016 59 0.041 1.041 58 0.042 1.067 57 0.043 1.092 56 0.046 1.181 55 0.052 1.321 54 0.055 1.397 53 0.059 1.511 52 0.064 1.613 51 0.067 1.702 50 0.070 1.778 49 0.073 1.854 48 0.076 1.930 47 0.079 1.994 46 0.081 2.057 45 0.082 2.083 44 0.086 2.184 43 0.089 2.261 42 0.094 2.375 41 0.096 2.438 40 0.098 2.489 39 0.099 2.527 38 0.101 2.578 37 0.104 2.642 36 0.106 2.705 35 0.110 2.794 34 0.111 2.819 33 0.113 2.870 32 0.116 2.946 31 0.120 3.048 30 0.129 3.264 29 0.136 3.454 28 0.141 3.569 27 0.144 3.658 26 0.147 3.734 25 0.149 3.797 24 0.152 3.861 23 0.154 3.912 22 0.157 3.988 21 0.159 4.039 20 0.161 4.089 19 0.166 4.216 18 0.169 4.305 17 0.173 4.394 16 0.177 4.496 15 0.180 4.572 14 0.182 4.623 13 0.185 4.699 12 0.189 4.801 11 0.191 4.851 10 0.194 4.915 9 0.196 4.978 8 0.199 5.055 7 0.201 5.105 6 0.204 5.182 5 0.206 5.220 4 0.209 5.309 3 0.213 5.410 2 0.221 5.613 1 0.228 5.791 A 0.234 5.944 B 0.238 6.045 C 0.242 6.147 D 0.246 6.248 E 0.250 6.350 F 0.257 6.528 G 0.261 6.629 H 0.266 6.756 I 0.272 6.909 J 0.277 7.036 K 0.281 7.137 L 0.290 7.366 M 0.295 7.493 N 0.302 7.671 O 0.316 8.026 P 0.323 8.204 Q 0.332 8.433 R 0.339 8.611 S 0.348 8.839 T 0.358 9.093 U 0.368 9.347 V 0.377 9.576 W 0.386 9.804 X 0.397 10.08 Y 0.404 10.26 Z 0.413 10.49