Grinding machine

920,578. Grinding. HAMMOND MACHINERY BUILDERS Inc. Sept. 7, 1959, No. 30496/59. Class 60. A tool-grinding machine having a grinding wheel 15, Figs. 2 and 3, mounted for oscillatory movement comprises a plurality of supports 20 which are located within a trough 17 forming part of a hood surrounding the grinding wheel and have concave upper faces in each of which the convex underface of a member 104 depending from the lower face of a work-table 24 can rock as determined by a manually-operable shaft 109 co-operating with a rod 105 projecting from one of the members 104. The work-table 24 is thus supported for tilting about a horizontal axis in a plane adjacent the grinding surface of the wheel 15. The grinding wheel 15 is mounted to oscillate transversely of its axis by the means described in Specification 860,084. The structure comprising the table 24, members 104, supports 20, trough and hood are carried by a base 16, Fig. 9, which is mounted on rails 30, 31 for movement parallel with the axis of the wheel spindle 14, ball-bearings and inner and outer guide-ways 36, 37 and 44, 45 being recessed into the rails and the downwardly projecting flanges 26, 27 of the base. The central portion 73 of the base 16 is raised to accommodate a power cylinder 74, Fig. 4, having, one end pivotally attached to the machine frame 11 and a pistonrod 75 secured to a downwardly-extending arm 72 at the front edge of the base 16. Adjustable stops 61, 62 control the range of movement of the base and a locking screw 95 operable by a knob outside the machine may be used to hold the base relative to the frame 11. A switch 81 is connected to the source 79 of pressure fluid to control the direction of flow to the powercylinder 74, the switch being operated by a plunger 82 when contacted by an actuating rod 85 supported at its inner end by a split-nut type of back-lash eliminating device 88, 89 of the type disclosed in the Specification referred to above, the outer end having a bearing 87, an indicator 93, Fig. 2, and calibrated dial whereby the plunger 82 may be engaged by the rod 85 when the base reaches a precise, predetermined, position during its movement towards the wheel 11. In the fully manual operation of the machine the table 24 is positioned as desired with respect to the grinding wheel and is locked by the screw 95, the tool being hand-fed across the table in a conventional manner. When semi-automatic operation is required, the power-cylinder 74 is replaced by a spring-loaded