Patent GB-334544-A (GB)
Title: Improvements in cutting devices for surgical and other purposes
IPC: A61F15/02
Filed: 1929-04-29
Abstract: 334,544. Leech, C. B., (Assignee of Beatlie, E. J.). April 8, 1929, [Convention date]. Trephining and like appliances; cutting plaster bandages.-A portable cutting appliance, particularly applicable to cutting and removing plaster .bandages, but also utilizable in cutting bone or in trephining and in cutting other material, comprises a casing 33, Fig. 1, containing a shaft 38 driven at high speed, preferably 8,000-10,000 r.p.m., by an electric motor 31 through a flexible shaft 32 and helical gearing 36, 37. The shaft 38 is grooved at 39 to receive a pin 40 on a toolcarrying shaft 41 which is mounted in combined radial and thrust ball bearings 42, 43 and carries the tool 14 formed integral therewith or secured thereto by screwing. The shaft 41 is shouldered at 48 to prevent withdrawal during working. The lower end 45 of the casing 33 in the form of a boss, is covered by a sheath 44 rotatably secured by a screw 46 engaging an annular groove 46a in the boss and having a longitudinal groove engaged by a rib on a slide 59 carrying a tool guide 60. The slide 59 may be secured in any position in the groove by clamping screws in the sheath 44. The apparatus is cooled during working by a volatile liquid such as methyl chloride introduced through a flexible tube 56, the vapour of the liquid escaping through holes 57, 58 in the sheath 44 and a spacing member for the tool-shaft bearings respectively. The tool 14, Figs. 1 and 6, is a combined drill and side-cutting tool and is provided with a. number preferably four, of helical grooves 52 having cutting edges 55 facing in the same sense as that of the progression of the helices, the helical grooves shown in Fig. 6 for example being left-handed looking towards the front of the tool. The following faces 53 of the grooves are undercut, and the unwanted edges 54 are bevelled. Two diametrically opposite grooves 52 extend to the point of the tool and permit of its use as a drill; the other two grooves terminate short of the point. The guide 60, Fig. 1, comprises a bifurcated lever straddling the tool and pivoted about a point 61 on the slide 59. The guide may be set at any desired angle by a screw 64 engaging an arcuate guide 65. In use the material is first drilled and then cut by moving the tool laterally through it, the guide being pressed against the surface and the tool being therefore at an angle thereto. The Specification as open to inspection under Sect. 91 (3) (a) describes a small tool 14, Fig. 7 (Cancelled), about 1/16 in. in diameter provided with an additional foot 28 in the form of a disc mounted at an angle to the tool on a strut 29 secured to the sheath 44, the guide-foot 28 being held against the underside of the skull during a trephining operation thereby producing an undercut aperture as shown. For cutting and removing plaster bandages a rectangularly mounted guide foot is provided and the guide 60 if employed is set at right angles to the axis of the tool. This subject-matter does not appear in the Specification as accepted. Specification 334,527 is referred to.