How does the bobbin mechanism work and how does the needle thread catch the thread from the bobbin?
A. RAGHUNATH
Musiri, Tamil Nadu
The sewing machine is a machine incorporating many intricate mechanisms that is used to produce the fine stitch.
Two thread rolls are used in order to finish the stitching. One of them is placed on the top of the machine and the end is passed through the eye of the needle.
The other roll is entwined around the bobbin which also rotates as the machine is under operation. This is placed just below the platform where the body of the machine is placed.
The hook ring is an integral part of the mechanism that is a half-ring and serves the purpose of forming the actual stitch, the mechanism which is described below.
Needle movement:
The rotating driveshaft in the arm of the machine connects to the needle bar through levers in the head to produce the up and down movement of the needle.
Stitch making:
The drive shaft has a vertical crank attached to it, going down under the base plate. Again, by a series of levers, this connects to a hook ring. The hook ring picks up the upper thread and guides it round the bobbin holding the lower thread.
Using the up and down movement of the needle and the rotation of the hook ring the two threads are looped together to form the stitch.
Working-How the thread catches the thread from the bobbin?
When the needle pierces the fabric on the down stroke, the thread on one side will lie in the groove.
When the needle starts to rise again, the thread in the groove rises with it, but on the other side, the thread is pinched between the cloth and the side of the needle. This friction against the fabric causes the thread to be retarded and a loop is formed just above the eye of the needle.
The upward stroke of the needle creates the crucial moment in the sewing cycle; the action takes place beneath the cloth.
T. VISHWARTH
NIT, Warangal
Andhra Pradesh
