| 摘要 |
A pair of carriages are movable in mutually orthogonal directions and include guides which cross or intersect and which extend perpendicular to the directions of carriage movements. The guides overlie a table upon which a pattern is placed and a manually movable targeting member slidably engages the guides at their intersection and carries a window having a cross hair sight. In moving the targeting member so that the cross hairs align with a desired point on the pattern, the guides and carriages are moved. Another table is disposed below the pattern table and upon which the plate to be scribed is positioned. Tractors are provided, one of which is movable in the direction of one carriage and carries a track projecting perpendicular to such direction. The other tractor is movable along the track and carries a retractable stylus. A joy stick control switch is provided on the targeting device to cause either one of the tractors to move in one direction only and the tractors include switches which are operated according to the locations of the guides to stop tractor movement. xhe tractor switches effect reverse motion of the tractors if the guides overrun the tractors. Precise positioning of the tractors is effected by toothed latch bars which have a number of sets of teeth, each set having a different pitch.
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