Thread trimmer system for in-line chain stitch sewing machine

A method for severing the needle and looper threads of a chain stitch formed in a piece of material by a sewing machine having a needle plate, a needle carrying the needle thread through the material and the needle plate to form a needle loop of needle thread therebelow having a needle side running to the needle, a looper carrying the looper thread through the needle loop, and a spreader receiving the looper thread from the looper, said method comprising the steps of:

• positioning a stationary knife below the needle plate so that the edge thereof is oriented to sever the needle and looper threads;
• positioning a spring below the stationary knife so that is biased in a direction toward the stationary knife;
• slidably mounting a movable knife between the stationary knife and the spring which yieldingly urges the movable knife thereagainst, the movable knife having one penetrating end with a pair of axially offset barbs, a lagging barb and a leading barb closer to the penetrating end of the movable knife than the lagging barb;
• extending the movable knife through the needle loop so that said leading barb hooks and the needle side of the needle loop and the lagging barb hooks the looper thread;
• and
• retracting the penetrating end far enough beyond the edge of the stationary knife to sever the needle and looper threads carried by the barbs.

A method for severing the needle and looper threads of a chain stitch formed in a piece of material by a sewing machine having a needle plate, a needle carrying the needle thread through the material and the needle plate to form a needle loop of needle thread therebelow having a needle side running to the needle, an in-line looper system including a looper carrying the looper thread through the needle loop, and a spreader receiving the looper thread from the looper, said method comprising the steps of:

• severing the needle side of the needle loop below the needle plate;
• severing the looper thread below the needle plate leaving a severed supply end from the looper;
• and
• holding the severed supply end in place for a next stitch to prevent it from slipping through the looper.