| 摘要 |
1,202,086. Drills. BARWORTH FLOCKTON Ltd. 24 Sept., 1968 [10 Oct., 1967], No. 46236/67. Heading B3C. A drill 1 has a series of cutting diameters with an end skirt 21, the cutting edges 12 being formed by three flutes. A pilot drill 8, which may be a centre drill or a twist drill, is held by a grub screw 26. A set of such drills may be provided having cutting diameters of from 1<SP>15</SP>/ 32 inches up to 2<SP>37</SP>/ 6 4 inches, in steps of <SP>1</SP>/ 84 inch. A set of metric drills may be provided having cutting diameters from 35À5 mm. to 62 mm. in steps of 0À5 mm. |
