Tacking Machine, Semiautomatic

a semiautomatic sewing machine for producing straight or decorative thread tacking on footwear, headwear, and other types of sewn articles. The tacking is a short line made of stitches with shuttle or chain interweaving of the threads. The machine first lays out the lengthwise tacking threads and then winds a thick zigzag line around them. The stitches are arranged automatically by the machine according to a predetermined pattern by means of programming units, usually cams of the appropriate shape driven by a reduction gear with a preset gear ratio. The operations of mounting the semifinished product on the clamp holder, starting the machine, and removing the semifinished product (after the machine shuts down automatically and the ends of the threads are cut off) are performed manually. Semiautomatic tacking machines perform up to 5,000–6,000 operations in an eight-hour period. They may be equipped with additional programming devices for tacking other preset shapes.