Adjust the bobbin screw. Also, check if it is broken.
If your stitch is too loose, the fabric will not be joined tightly.
Lower parts of the lockstitch sewing machine are the feed dog.
Upper and ther lower part of machine
There are two tension adjustments on the home sewing machine. One is the top tension and the other is the bobbin tension. Both tension settings regulate the tension on the sewing thread. The top tension regulates the amount of tension on the thread that moves between the thread spool and the needle which produces the top stitches in your seam. The tighter the tension, the more taut the thread. The looser the tension, the more slack the thread. If tension is too high, the thread is strained, the stitches are tighter and the thread may break. If tension is too low, the thread is slack, and the stitches are loopy and loose. At ideal tension, the thread moves smoothly through the thread path and produces top stitches that are nice and even. The bobbin tension regulates the thread spinning in the bobbin and being pulled up into the bottom stitches. At ideal tension, the bottom stitches are nice and even, and cannot be seen from the top of your stitching. Refer to your sewing machine manual for the ideal tension setting on your particular sewing machine.
Upper and ther lower part of machine
Upper and ther lower part of machine
That entirely depends on the specific sewing machine. On some machines there is a button you push yet on others there is a lever you lower.
the presser foot the balance and the feed fog
To adjust the lower tension on an oscillating hook type machine you would turn a screw on the inside of the machine. You want to locate the bobbin tension screw and turn it 1/4 of a turn to the left.
The lower bobbin carries the lower thread and the upper bobbin carries the upper thread to use when the sewing machine is working (NOT SOWING Machine)!!! The needle carries the upper thread - NOT the lower thread - as the question asked!!
The first sewing machine was invented by a German named Charles Fredrick Wiesenthal. Wiesenthal invention of the first device for sewing are consist of a double pointed needle with a tiny hole on the lower part.
the two ajor types of the lockstitch are the upper and lower parts!