Types of machines and their characteristics

Sewing is a creative and interesting skill. The knowledge of sewing give a confident feeling when it is applied to the construction of garments. The earlier method of sewing by hand is not applicable for all stages of garment making. Therefore, considerable emphasis is given to machine sewing. There are several machines in the market today, each with its own desirable features and advantages. Sewing machines range from most basic having only simple lock stitch to the electronic machines that use advanced computer technology having various functions for example piping, binding, ruffling, pleating, darning, hemming and even making buttonholes and attaching fasteners. A good sewing machine is required to obtain quality products. One has to be familiar with the characteristics of different types of machines for selecting appropriate machine, depending upon the ability and requirements of the person.

TYPES OF SEWING MACHINES:

Sewing machines are now available in various models such as domestic model, tailor model, industrial model, portable and cabinet models. They may be operated by hand, treadle or electric motor.

Hand – Operated Sewing Machine:

This is the simplest form of sewing machine which is operated by hand. A detachable handle provided to the flywheel is used to operate the machine. This machine is generally suitable for domestic purpose because it does not help in speeding up the work.

Treadle Sewing Machine:

This machine is exactly like the hand sewing machine but it is operated by foot using an additional stand. In this type the balance wheel is operated by a belt with the help of lower stand, which is driven by feet. This machine operates faster than that of the hand-operated machine. This machine is suitable where there is no power supply. When handling

this machine both the hands are free to handle the fabric, speeding up the work. Even some of the heavy-duty machines are operated by this method.

Electric Sewing Machine:

This is the fastest sewing machine. One needs practice to handle it. In an electric machine the balance wheel comes to motion by a belt, which is attached to an electric motor.

PARTS OF A SEWING MACHINE AND THEIR FUNCTIONS:

The basic structure of sewing machine is the same whether it is hand-operated sewing, treadle sewing machine or electric sewing machine. The basic parts of a sewing are listed below and seen in Fig.

1. Spool pin: It is fitted on top of the arm to hold the reel.
2. Thread guide: It holds the thread in position from the spool to the needle.
3. Tension disc: The two concave discs put together with the convex sides facing each other. The thread passes between the two. The tension of the thread is adjusted by a spring and nut which increases or decreases pressure
4. Take up lever: It is a lever fitted to the body of the arm. Its up and down motion feeds the thread to the needle and tightens the loop formed by the shuttle.
5. Needle bar: This is a steel rod to hold the needle at one end with the help of a clamp. Its main function is to give motion to the needle.
6. Bobbin case: This moves into position to catch the top thread and form the stitch as the needle is lowered into the bobbin chamber.
7. Presser foot: It is fixed to the presser bar to hold the cloth firmly in position when lowered.
8. Presser foot lifter: A lever attached to the presser bar for raising and lowering the presser foot.
9. Stitch regulator: This controls the length of the stitch.
10. Bobbin winder: A simple mechanism used for winding thread on the bobbin.
11. Fly Wheel: When this is made to revolve, it works the mechanism of the motion
12. Clutch or Thumb Screw: This is in the center of the fly wheel and it engages and disengages the stitching mechanism.
13. Slide Plate: A rectangular plate, which facilitates the removal of the bobbin case without lifting the machine.
14. Needle Plate or Throat Plate: A semi-circular disc with a hole to allow the needle to pass through it.
15. Feed dog: This consists of a set of teeth fitted below the needle plate. It helps to move the cloth forward while sewing.
16. Face plate: A cover which on removal gives access to the oiling points on the needle bar, presser bar and take-up lever.
17. Spool pin for bobbin winding: Spool of thread is placed on this at the time of bobbin winding.

PREPARATION FOR STITCHING

Before starting actual machining, you should check that the needle of the machine is of correct size, is sharp and correctly set. The bobbin should be evenly set. Briefly, the various steps of prepreparation are:
• Winding the bobbin
• Upper Threading
• Drawing the bobbin thread
• Tension adjustments
• Pressure and feed adjustments
• Selection of thread and needle

A perfect stitch can be obtained only when the thread selected is suitable to the material to be stitched and the needle is of the correct size. For stitching on delicate thin fabrics, use fine thread and fine needle. For heavy fabrics, needles and thread size should be larger. The following Table 1 will be a guide to help selection of appropriate needle and thread sizes.

Types of Threads

The natural fibre threads available in the market are cotton and silk. Synthetic threads are usually made from polyester and terylene. Threads whether natural or synthetic are produced in various thickness: higher the number, finer is the thread and smaller the number, coarser is the thread. It is important to remember that the same thread should be used for the bobbin and top spool.

Selection of needles

Machine needles are selected according to the weight and other characteristics of the fabric, as well as the thread type being used for construction. Generally, a needle should be fine enough to penetrate the fabric without damaging it and yet have an eye, which is big enough so that the thread does not fray or break. Needles come in various sizes, from very fine (size 9) for light weight fabrics to thick (size 18) for very heavy weight and dense fabrics.

COMMON MACHINE TROUBLES

The sewing like any other machine, gives troubles of stitching like thread breaking, uneven stitching, puckering, bending and breaking of needle, looping of threads, skipping of stitches, etc. Little problems with the sewing machine can be very irritating and time consuming. They can happen to even the most experienced seamstress. A person operating the machine should be able to rectify these and solve the problems. Some of the common machine problems are listed below:

1.  breaking needles
2.  looping of stitches
3.  skipping stitches
4.  variation in stitch length
5.  puckered seams
6.  upper thread breaking
7.  lower thread breaking
8.  machine not feeding properly
9.  machine working heavily
10.  layers feed unevenly
11.  fabric does not feed in straight line
12.  cause damage to fabric
13.  Puckering on both layers of fabric
14.  Puckering on under layer only
15.  Shows feed marks on the under side
16.  Fabric is damaged or holes around the stitches

CARE AND USE OF SEWING MACHINES

A sewing machine needs care for its smooth running. It should be cleaned and oiled regularly to ensure satisfactory sewing and long life. When not in use, your machine should be covered to prevent dust accumulation on it. Use a small dry brush or old toothbrush and soft cloth to remove dust and lint. You should always remove lint deposits, dust and thread bits before oiling any part of the machine. Use a pointed instrument like a needle to pick out the bits of thread and lint that cannot be brushed out.

It is necessary to oil and lubricate the machine periodically. If the machine is used everyday, oil it once a week. After oiling, wipe off the surplus oil and place a piece of folded fabric under the presser foot to absorb any excess oil. To oil thoroughly, remove the upper thread, needle plate, slide plate, face plate, bobbin case, needle and presser foot. Oil the holes on the underside first, after cleaning and then proceed to the upper side. Use only few drops of oil in each hole. Never use coconut oil. Machine oil of different brands may be used for different models of sewing machine, but should be used as recommended in the instruction book.

If the machine becomes gummed with oil, put a drop of kerosene or petrol in each oil hole and joints and run it rapidly for several minutes. Wipe off and re-oil it with machine oil. The motor of electric sewing machine should be greased periodically.

Summary

The knowledge of sewing give a confident feeling when it is applied to the construction of garments. The various parts of a sewing machine and their functions helps one  to understand the working of a sewing machine. A brief up on the common machine problems help us to understand and rectify the problems. Above all the care of sewing machine is rather important for a long service of the machine.