Patent GB-296148-A (GB)
Title: Improvements in or relating to drilling and like jigs
IPC: B23B47/28
Filed: 1927-06-14
Abstract: 296,148. Bristol Aeroplane Co., Ltd., and Garrett, W. L. June 14, 1927. Drilling. - A drilling is made readily adjustable for receiving and holding differently shaped work-pieces, and comprises a base 20 having guides 21 in which is slidable a block 24 carrying a drill guide 30 and a workengaging member 35. The other end of the work 37 is supported by a centre 48 slidable in a head 47 adjustably clamped to the base, a, stirrup being pivoted at 51 on the head and carrying a screw 49 for engaging the centre. In the working position the stirrup rests on pins 52 but it may be rotated to release the centre and allow it to be withdrawn from the work. The block 24 is normally pressed towards the work by a spring 28, this movement being limited by nuts 27 on a rod 25 attached to the block. In one form of jig, jaws 40, Fig. 2, are pivoted to the sliding block at 41 and have projections 42 adapted to engage stops 43, 44 on the base to open and close the jaws relatively to the work when the block is moved in the respective direction, one or both of the stops 44 being adjustable. The operative faces of the jaws are provided with hardened steel rods 53, secured in recesses or forks, for engaging the stops and work. The member 35 is interchangeable to suit the work and is adjustable in guides on the block by means of a screw 38. The work rests on a second drill guide 32 or an adjustable anvil. In operation, the member 35 is adjusted to the correct position relatively to the guide 30 and the work piece 37 is mounted thereon. after which the centre 48 is pushed forwards by the screw 49, thereby seating the work accurately against the member 35 and then moving the block 24 against the spring 28 and causing the jaws 40 to grip the work laterally. In a modified construction the work is gripped laterally by jaws slidable transversely in the block 24 and actuated, through movement of the latter, by wedges secured to the base, one or both of the wedges being axially adjustable. In a further modification, for work which requires to be drilled from opposite sides, the member 35, Fig. 9, is axially adjustable by the screw 38 in a sleeve 70 which replaces the block 24 and is slidable and rotatable on a hollow shaft 69 fixed to the base. A hollow member 64, in which the sleeve 70 is slidable but not rotatable, is rotatably mounted by means of a ball bearing 63 and a lug on the fixed part 65 engaging a collar 68, and carries the adjustable stops 44 for the jaws 40 pivoted at 41 to.the sleeve 70. For indexing the work, lugs 78, 79, Fig. 10, on the sleeve 70 are adapted to engage between blochs 72, 73, adjustable by a right and left hand screw 74, and a fixed block 76. After a hole has been drilled in the position shown in Fig. 10, the blocks 72, 73 are separated, releasing the lug 79 and allowing the work to be rotated until the lug 78 engages the block 76, whereupon the block 72 is pressed against it to secure it. In a. still further modification, the upper part of the block 24 which carries the drill guide 30 is adjustable relatively to the lower part which carries the jaws 40 by means of screws passing through slotted holes. Slotting.-The jig may also be used for slotting nr broaching operations ,in which case the broaching &c. cutter has a body or shank which fits the bush 30.