Letter d hss s/s Jobber Drill - Sherwood

Sherwood: Lette D HSS S/S Jobbe Dill Letter 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