A thread inserting device includes a guide pin having a thread capture portion at its tip for capturing a thread; a holder that fixedly holds the guide pin; a main body (first and second main bodies) slidably mounting the holder; and a thread cutting portion provided to the main body for cutting the thread to a length equal to or smaller than the protrusion of the thread capture portion from a thread captured position on a thread tip 6a side after the thread is captured by the thread capture portion. By shifting the holder, the thread capture portion is protruded to a predetermined length from the main body, and the thread cut to a predetermined length by the thread cutting portion is inserted into the thread inserting hole.

A thread inserting device includes a guide pin having a thread capture portion at its tip for capturing a thread; a holder that fixedly holds the guide pin; a main body (first and second main bodies) slidably mounting the holder; and a thread cutting portion provided to the main body for cutting the thread to a length equal to or smaller than the protrusion of the thread capture portion from a thread captured position on a thread tip 6a side after the thread is captured by the thread capture portion. By shifting the holder, the thread capture portion is protruded to a predetermined length from the main body, and the thread cut to a predetermined length by the thread cutting portion is inserted into the thread inserting hole.

A method for preventing seam ravel of multi-thread chain stitches is provided. After normal sewing is terminated with a looper set in a forward movement state, a state in which a needle thread loop caught by the looper is subjected to position-holding at a position closer to a forward movement end of the looper than a descent position of a needle is maintained until the needle descends through the needle thread loop caught by the looper. Thereafter, the position-holding of the needle thread loop is released to permit a sewing action for at least one stitch, thereby allowing the needle thread loop to be self-looped with a needle thread held by the needle. This surely strongly prevents the seam ravel of multi-thread chain stitches formed by the single needle, irrespective of the dimension of tension applied to the needle thread and the looper thread.

A method for preventing seam ravel of multi-thread chain stitches is provided. After normal sewing is terminated with a looper set in a forward movement state, a state in which a needle thread loop caught by the looper is subjected to position-holding at a position closer to a forward movement end of the looper than a descent position of a needle is maintained until the needle descends through the needle thread loop caught by the looper. Thereafter, the position-holding of the needle thread loop is released to permit a sewing action for at least one stitch, thereby allowing the needle thread loop to be self-looped with a needle thread held by the needle. This surely strongly prevents the seam ravel of multi-thread chain stitches formed by the single needle, irrespective of the dimension of tension applied to the needle thread and the looper thread.

A thread inserting device includes a guide pin having a thread capture portion at its tip for capturing a thread; a holder that fixedly holds the guide pin; a main body (first and second main bodies) slidably mounting the holder; and a thread cutting portion provided to the main body for cutting the thread to a length equal to or smaller than the protrusion of the thread capture portion from a thread captured position on a thread tip 6a side after the thread is captured by the thread capture portion. By shifting the holder, the thread capture portion is protruded to a predetermined length from the main body, and the thread cut to a predetermined length by the thread cutting portion is inserted into the thread inserting hole.

A sewing machine with a threading and air supply selecting device includes a base with a main shaft for driving at least one thread wiper, and a guiding pipe is provided on the thread wiper. On the base is further disposed an air supply device driven by a drive force source. Between the air supply source and he guiding pipe is disposed a pipe-moving device for moving the connecting pipe to the guiding pipe. A swing arm of a connecting rod assembly serves to control ON and Off of the air supply source. A directional positioning device is used to stop the main shaft from rotation, when the air supply source is working.

A sewing machine with a threading and air supply selecting device includes a base with a main shaft for driving at least one thread wiper, and a guiding pipe is provided on the thread wiper. On the base is further disposed an air supply device driven by a drive force source. Between the air supply source and he guiding pipe is disposed a pipe-moving device for moving the connecting pipe to the guiding pipe. A swing arm of a connecting rod assembly serves to control ON and Off of the air supply source. A directional positioning device is used to stop the main shaft from rotation, when the air supply source is working.