FUNDAMENTALS OF CLOTHING CONSTRUCTION 3(1+2)

Lesson 3 : Sewing Machine

Selection of thread and needle, changing needle

1. Selection of thread: Sewing threads are available in various sizes and sizes are indicated through numbers. The higher the number the finer the thread. Threads are also made from different materials like polyester, cotton and their blends. Different fabrics require different sewing threads. Ex: For Denim, a cotton thread of 20-40 size or a mercerized cotton ‘heavy duty’ thread need to be sued. For poplin, a cotton thread (50 size) or spun polyester thread can be used. For delicate fabrics like Voile a cotton thread of 80-150 size can be used.

   For temporary hand stitches a contrast colored thread can be used. For permanent stitches, a thread that is a shade darker than the fabric can be used. A perfect stitch is formed only if the thread size matches with the fabric type and needle size.

2. Selection of Machine Needle: Machine Needles are available in various sizes ranging from 10-16. Selection of machine needle is dependent on

   • Type of Fabric: Heavier fabrics require thicker needles and fine fabrics require fine needles. If fine needles are used for heavier fabrics higher strain is placed on the needle which may eventually break the needle. Coarse needles when used on fine fabrics will split or puncture the fine yarns of the woven fabric, leading to puckering of the fabric.

   Relation between the needle and the thread: if a fine thread is used in a thicker needle, the stitching will be weak, as the bigger holes made by the needle are not completely filled by the fine thread. Similarly a coarse thread in a fine needle will frequently break because of the excessive friction of thread passing through the small eye of the needle.

   Table 1: Relationship of thread and needle sizes by weight of fabric

   Fabric and purposes	Machine needle size	Machine stitches per inch
   		For Seams
   Filmy Organdy , net , organza	9	18-20
   Sheer Voile, lawn, chiffon, silk and manmade sheers	9, 11	16-18
   Plastics	9-10	10
   Light weight Cotton chambray, gingham, taffeta, sheer wool , crepes	11, 14	14-16
   Medium-light Cotton prints, chintz, dress linen, lightweight wool fabrics, single knits, double knits	14	12-15
   Medium-heavy Heavy corduroy, slip-cover fabrics, khaki, heavy muslin	16-18	10
   Heavy Denim, awning materials, sailcloth, duck, heavy drapery fabrics	18	8
   Very heavy Heavy duck, canvas, upholstery fabrics, tarpaulin	19	6

   
   

3. Changing the needle: Setting the needle appropriately into the bar, avoids frequent breaking of upper thread. Following are the steps for changing the needle.

• Set the needle bar at its highest position by moving the fly wheel.
• Loosen the needle clamp to remove the old needle.
• Check to see if the needle is straight or not. Blunt, bent needles should never be used. Place the flat side of the needle into the groove of the needle bar, push it up until it stops at the end of the groove and tighten the needle clamp.

Improper threading of the needle results in frequent thread breakage at the eye of the needle. It will also cause the fabric to pucker and snag the threads of the fabric.