Patent GB-153186-A (GB)
Title: Improvements in etching machines
IPC: B44B3/00
Filed: 1919-12-03
Abstract: 153,186. Eaton, W. S. Dec. 3, 1919. Engraving.-A pantographic etching machine of the type adapted to reproduce a pattern in a resist on a printing surface by means of a pantograph mechanism capable of adjustments to extend, condense, or vary the inclination of the reproduction as compared with the pattern, comprises a tool - carrying arm adapted to be given universal relative movement with respect to a work bed, a member engaging the arm to raise the tool from the work or to allow it to descend under gravity, and a resistance device operating on the arm and controlling its descent whereby the tool is lowered gently on to the work. An arm 27, Fig. 3, to the end of which is fixed an etching- tool 28, is adjustably secured by a clamping-ring 39 and screw 40 to a frame 37 pivoted within a voke 36 and provided with a forked end 52 engaging an adjustable stop 51 on a rod 50 terminating in a plunger 49, Fig. 4, provided with a ball valve 54 and a screwactuated needle valve 58, and slidably mounted in a cylinder 48 containing a sealing fluid such as oil or mercury. A bar 41, Fig. 3, adjustably mounted in a sleeve 41<a> secured to a rod 44 connected to a treadle-operated crank 45, Fig. 1, is pressed upwards to raise the arm 27 by a torsion spring 46 on the crank and a spring 42 engaging a collar 43 on the sleeve 41<a>, and is released by the treadle. In dropping, the arm 27 raises the plunger 49, causing a vacuum within the plunger so as to resist the motion of the arm and lower it gently on to the work. The needle valve 58 may be regulated to vary the amount of air entering and therefore the speed at which the arm falls, and the ball valve 54 allows unrestricted upward motion of the arm 27. The work, such as a lithographic stone 26, is clamped between a plate 21 and an adjustable dog 22 on a bed 12, mounted so as to be adjustable in two directions at rignt angles by means of racks and pinions, on a table 10 fixed to the top of a column 4 extending upwardly from a table 2, Fig. 1, on which is a suitable holder 3 for the pattern. The yoke 36, Fig. 3, is adjustably carried in a sleeve 61 fixed to a carriage 29 supported by inverted ball cups 30, 31, 32 on balls 33, 34, 35 resting in ball-cups 6, 7, 8 carried by a head 5 fixed to the column 4. A stylus 65 for tracing out the pattern is slidably mounted in the end of a swinging arm 64 pivoted at its upper end to a ring 73 pivotally carried by the carriage 29, the axes of the pivots being at right angles. Shoes 67 engaging opposite angular parts of the arm 64 are pivoted in a ring 68 pivotally mounted, so that the axes of the pivots are at right angles, in a yoke 66 secured by a screw 74 to a split sleeve 70 sliding on the column 4, adjusted by a rack and pinion, and secured by a clamping screw 75. The reproduction may be extended or condensed in comparison with the pattern by adjustment of the sleeve 70, and in order to vary the breadth of the reproduction relatively to its length the ring 67 is provide with lugs 72 having a number of holes to engage pivots 69 in the yoke 66, whereby the height of one set of pivots may be altered relatively to the other. Also, in order to incline the reproduction, the yoke 66 may be angularly adjusted about the screw 74.