Thread tension device for sewing machines

867,694. Sewing machines. SINGER MANUFACTURING CO. Dec. 22, 1959 [Dec. 23, 1958], No. 43568/59. Class 112 [Also in Group XXII] In a sewing machine thread tensioner comprising a fixed stud 18, a thread-engaging wheel 40 rotatable on the stud, and adjustable friction means carried by the stud for resisting the rotation of the wheel, the latter is formed from a pair of concentric annular members 50, 51. The periphery of each of which is formed with an annular series of openings 58, 581 defining radial fingers 59, 591, each finger being disposed opposite an opening in the opposing member and being formed between its ends with an offset portion 60, 601 protruding through said opposite opening. A bush 11, secured to the sewing machine, houses the stud 18 secured thereto by a set screw 16. A check spring 23 has one end disposed in an axial groove 22 formed in an enlarged portion 21 of stud 18, the other end of spring 23 projects radially through a slot 14 in bush 11 and ends in a thread-engaging hook 25. Wheel 40 is disposed between two friction pads 41, the inner one abutting a fixed cup washer 26 and the outer one abutting a slidable pressure washer 28 biased inwardly by a spring 31 adjustable by a nut 32. A pin 62, axially disposed in stud 18, abuts a diameter bar 29 on washer 28, inward movement of pin 62 thereby serving to release the thread tension. Member 50 of wheel 40 is formed with a hub portion 52 journalled on stud 18 and with an annular groove 53 which initially produces an annular bead 54. Member 51 has a large central aperture 56. The members are clamped together and electrical current is passed to produce projection welding 541 therebetween along the bead 54. The fingers 59, 591 are inclined to one side to form the offsets 60, 601 of from 1/ 2 to 1 times the thickness of the members 50, 51, are flared outwardly to form a peripheral groove which provides a sinuous path for the thread wound therein, and end in continuous rims 57, 571. It is stated that, owing to this construction, the device, when once adjusted to impart the proper frictional resistance to one given thread, will impart without adjustment substantially the same frictional resistance to various threads having widely different characteristics.