Sewing machine bartack and chain stitch

Chain stitch:When sewing, the sewing machine puts the material to be sewed on the needle plate under the needle, and fixes it with the presser foot. When sewing starts, the needle will pass through the fabric, and then the needle will pull out a loop. A loop-making device catches the loop before the needle is pulled out. The device moves in sync with the needle, and the needle then goes through the fabric again, and then through the loop again, and the cycle continues. The lock stitch sewing speed is very fast, but it is easy to take off the thread. Once a certain position of the stitch is loosened, the entire sewing line will be all off the thread.

Lockstitch: Like the chainstitch, it also requires the needle to pass through the fabric and then pull out a loop, which rises again as the feed dog feeds forward, and another loop is inserted.

But instead of making the two coils two different coils, connect them with another piece of wire unwound from the spool. As the needles pull the thread into the loop, the rotating shuttle grabs the loop with the hook. As the shuttle rotates, it pulls a coil around the thread coming from the spool.

This stitch is very strong and does not come off as easily as a chain stitch.