Patent GB-704657-A (GB)
Title: Improvements in or relating to blind-stitch sewing machines
IPC: D05B85/06
Filed: 1952-12-19
Abstract: 704,657. Sewing-machines. FAIRWEATHER, W. C. (Singer Manufcaturing Co.). Dec. 19, 1952, No. 32173/52. Class 112 Blind-stitching machines. In a machine with a ridge-forming element to project a ridge of the work into the path of the needle and with means for moving the ridge-forming element periodically, so that the height of the ridge of work varies, anchorstitches (penetrating all layers of the work) and skip-stitches (missing one layer of the work) are produced, a control linkage is provided to render the skipstitch mechanism operative or inoperative; in the latter condition the ridge-forming element remains in its most projected position and all the stitches are anchor stitches. The machine described is similar to that of Specification 707,286, having a work-arm 22 oscillatably mounted on a spindle 25 so that it can be lowered, by a knee or treadle lever, to permit insertion or removal of the work; the spindle 35 on which the ridge-former is fixed, is, however, journalled in the work-arm and is oscillated by an eccentric 42 on the main shaft 17 through a pitman 41, rock-lever 40, 38, and link 37, attached to an arm on the spindle 35. The work-arm is urged upwardly about its spindle 25 by a spring 72 (see below), its uppermost position being determined by a cam 43, on a spindle 44 mounted in the arm, engaging a stop plunger 55 carried by the frame member 10; the spindle 44 is adjusted angularly, to adjust the position of the work-arm; by worm-gearing 48 from a finger-actuated spindle 51, and the plunger 55 is reciprocated, to raise and lower the work-arm and thus form skip-stitches and anchor-stitches, by a member 57 actuated by an eccentric 60 on a shaft 62 which is driven by belt or gearing from the shaft 17 at a speed-ratio selected to give the required number of skip-stitches between successive anchor-stitches. The member 57 is urged to the left, and the work-arm is urged upwards, by the spring 72 adjustably attached at 69 to the member 57 and attached at its other end to a plunger which is arranged parallel to the plunger 55 and which is connected to the skirt of the work-arm 22 through a link and a twoarmed lever and link similar to those described in Specification 707,286; this arrangement of the spring removes any load on the eccentric 60 due to the force of the spring. The member 57 has an aperture which pivotally receives a sleeve 81 formed on a link 80 pivotally connected at 79 to an arm on a spindle 77; this spindle passes with clearance through the sleeve 81, and carries a hand-lever with means for holding it in either the position shown, causing some longitudinal movement of the member 57 to take place when it is oscillated by the eccentric 60 thus reciprocating the plunger 55 and producing skip-stitches as described above, or a position wherein the link 80 lies along a line joining the eccentric 60 to the point of connection between the member 57 and the plunger 55, when no longitudinal movement of the member 57 is possible and the work-arm thus remains stationary so that all the stitches are anchor-stitches.