Improvements in or relating to lathe tools, boring-bars or the like

807,921. Boring-bars; tool-holders. BIRMINGHAM SMALL ARMS CO. Ltd. April 20, 1955 [April 20, 1954], No. 11316/54. Class 83(3). A boring-bar, lathe-tool, &c., comprises a holder 21, Fig. 1, having a groove 23 with an undercut-wall against which the cutting tip 25, of dovetail cross-section, is forced by a wedge 29 operated by a screw 39. The tip may also be tapered to provide a rake-angle, and the wedge 29, located in a recess 27 in the side of the groove, has a frusto-conical shoulder engaged by a similar shoulder on the screw head. In another construction, Fig. 3, both walls of the groove receiving the tip 45 are undercut, and the tip is secured as before, by a wedge 47. A back-stop 49, of dovetail cross-section, for the tip is lodged in the channel by a stud 53, which bears against the bottom of a recess 51 in the channel. In the construction of Fig. 6, the tip is secured in the shank by a wedge surface 69 on the side of a cylindrical member 67 drawn into a passage 65 by a screw beneath the member 67. An end stop 75, either end of which may present an adjusting screw 79 to the tip, is located by its spigot 77 in either of two recesses 73 formed in the bottom of the channel. As applied to boring-bars (not shown), the tip is secured in an undercut chordal groove in the end of the bar.