522,164. Milling-machines. STEVENS, A. H. (Ingersoll Milling Machine Co.). Dec. 2, 1938, No. 35154. [Class 83 (iii)] A machine tool such as a milling-machine has work and tool supports movable relatively both longitudinally and transversely of the face of the cutter, the transverse movement being interrupted by means controlled by the engagement of a feeler with the surface of the work at a point where the cutter is correctly positioned for the removal of a layer of material from the work piece. In preparing a metal slab or ingot, particularly aluminium, for rolling, drawing or the like the work piece 10 is clamped to a table 11 moving over a bed 12 and is traversed past a large face-mill cutter 15 to remove a thin layer from one surface of the slab after which the work is turned and a layer removed from the opposite face. In order to determine the depth of cut, a feeler device 44 mounted parallel to the cutter spindle is adjusted at a predetermined distance behind the plane of the cutter face so that when the cutter and feeler assembly is moved towards the work until the feeler engages a point on the surface thereof, the cutter, which 'is then locked, will be in position to remove the required layer when the work is subsequently traversed. On completion of the operation the cutter is retracted, the carriage returned and the work reversed. The work carriage is driven by a worm 18 Fig. 8, engaging a rack 19 and operated by a feed motor 20 and a reversible rapid traverse motor 21 connected to the worm by differential gearing 22. A vertical wall of the carriage carries clamping heads 24 vertically adjusted by hydraulic cylinders 26 controlled from levers 28. The two pairs of hydraulically-actuated clamping-members 23 are controlled by levers 27. The slab is located by an end stop 29 and supported at 30, being finally secured against stops on the wall 25 by the clamping members. The cutter-spindle 31, driven from a motor 42 through belt-gearing 43. is journaled in a non-rotary quill 33. The feeler consists of a bar 44 splined in a hollow casing 45 mounted in guides in the tool head 14. A micrometer head 46 on the feeler bar coacts with a scale 52 to determine the setting, each quarter revolution of the head, determined by a spring-pressed ball, effecting an adjustment of 1/32''. The cutter and feeler are advanced simultaneously towards the work by a motor 59 driving through a clutch 73 and worm-gearing 61 a two-part shaft 62, 63, the former carrying a gear 65 actuating the quill 33 and the latter a gear 66 actuating a rack on the casing 45. When the feeler engages the work it is moved slightly backward whereupon a part 58 acts through a lever 54 to operate a switch S to stop the advance movement. The feeler may be separately retracted before the cutting traverse of the carriage by means of a hydraulic piston 69 secured to bar 44. In some cases the clutch 73 may be disengaged and the quill and feeler casing actuated manually by a crank operating gearing 80, 81 connected to the worm wheel 61. This manual train may be disengaged when not required. When the cutter has been axially positioned it is clamped against movement by a cap member 89 which is forced downwardly against the quill by a hydraulic, cylinder 96 acting through a lever 92. Electric controls are provided for securing an automatic machine cycle comprising rapid traverse of the carriage 11 from the Fig. 1 position to the gauging position and stop in this position, approach of the cutter and feeler till the feeler engages the work and stoppage and clamping of the cutter in this position, slow feed of the work past the cutter and stoppage at end of feed movement, unclamping of the cutter sleeve and return of cutter and feeler to starting position at which they are stopped ; and rapid return of the carriage to a stop in its initial position. The control circuit is shown in Fig. 8 and includes a starting switch 102, emergency stop switch 119 and traversing stop switch 111 all mounted on a control panel 14a. A series of other switches S1... S5 are automatically operated by moving parts of the machine. On closing the switch 102, the contactor C3 connects motor 21 to give rapid traverse of the carriage and also to energize solenoid 101 which moves valve 99 to admit fluid to cylinder 95 so as to unclamp the cutter quill, and to cylinder 70 so as to project the feeler 44. The contacts 107a form part of a hold-up circuit to keep the contactor C3 closed after the button 102 is released. This movement is stopped by actuating a switch S2 to break the hold-up circuit by an adjustable dog 122. Another dog releases switch S3. The closing of contacts S22 energizes contactor C4 to connect the motor 59 to advance the cutter and feeler to operative position and at the same time the switch S5 is operated to condition the circuit of the return contactor C5 of this motor. When the feeler touches the work the contacts S11 of switch S1 are broken thus breaking the circuit of C4 and stopping the motor 59. Simultaneously relay R4 is energized to complete the circuit of solenoid 100 which shifts valve 99a and admits fluid to retract the feeler bar and clamp the cutter quill. When clamping is completed, the build-up of hydraulic pressure closes a switch 120 to energize the feed motor contactor C1 for the operative movement which may be stopped by opening the switch 119. A dog 138 operates switch S4 to stop this motor at the required time. Simultaneously the contacts S41 are closed to cause energization of solenoid 101 so as to retract the cutter and feeler casing and project the bar 44 to its initial position. The backward cutter movement is stopped by actuation of switch S5 by the feeler casing part 45c. The closing of contacts S52 of this switch actuates return contactor C2 and produces the rapid return movement which is terminated by the dog 123 opening the switch S3. The stoppage of the feed or rapid traverse movements may be effected at any time by actuation of the switch 118 or 11 respectively.