Types and parts of a sewing machine

22 min

Let's begin

Walk through the tailors' corner of almost any market in Rwanda and you hear a steady clatter. Some tailors rock a cast-iron treadle with their feet; others press the foot control of an electric machine; one may be finishing edges on a fast overlocker. A tailor can sew a straight seam on a machine many times faster than by hand, and the stitches are even, tight and strong. You have already learned to sew stitches and seams by hand. This lesson introduces the machine that does the same work at speed: its main types, its parts, and what each part does.

Definition

Sewing machine: a machine that joins fabric with stitches made by a needle and thread, moving the fabric forward between stitches.

Lockstitch: the stitch made by most sewing machines. A top thread from the needle and a lower thread from the bobbin lock together between the layers of fabric, so the stitch looks the same on both sides.

Overlocker (or serger): a machine that trims the raw edge of the fabric and wraps it in thread loops in one step, to stop fraying.

Types of sewing machine

Type	Driven by	Strengths	Limits
Hand machine	a handle turned by one hand	cheap, portable, no electricity	slow; only one hand is free to guide the fabric
Treadle machine	a foot plate rocked by both feet, turning a large wheel and a belt	no electricity; both hands guide the fabric; robust and easy to repair	heavy; the sewer must keep a steady rhythm
Electric machine	a motor controlled by a foot pedal	fast; speed set by the pedal; often has zigzag and other stitches	needs electricity; motor and wiring can fail
Computerised machine	a motor and a small computer	many stitch patterns, buttonholes and embroidery chosen on a screen	expensive; repairs need a technician
Industrial machine	a powerful motor under a table	very fast; sews heavy fabrics all day in factories	one job only (e.g. straight stitch); loud; costly

The parts and what they do

Part	Function
Spool pin	holds the reel of top thread
Thread guides	lead the thread along the correct path
Tension discs and dial	grip the top thread so that it is pulled with the right force; balance it with the bobbin thread
Take-up lever	rises after each stitch, pulling the stitch tight and drawing thread off the reel for the next one
Needle bar and needle clamp	hold the needle and move it up and down
Presser foot and lifter	the foot holds the fabric flat on the feed dogs; the lifter at the back raises and lowers it
Feed dogs	small metal teeth that move the fabric backwards under the needle, one stitch length at a time
Needle plate (throat plate)	the metal plate under the foot, with a hole for the needle and guide lines for seam allowances
Bobbin, bobbin case and hook	the bobbin holds the lower thread; the turning hook catches the loop of top thread and wraps it round the bobbin thread to form the lockstitch
Slide plate	covers the bobbin area
Bobbin winder	winds thread from the reel onto an empty bobbin
Hand wheel (balance wheel)	turns the machine by hand to raise or lower the needle; always turned towards you
Stitch length dial	sets the length of each stitch in millimetres
Stitch width or pattern selector	on zigzag machines, sets how wide the zigzag is, or chooses a stitch
Reverse lever	sews backwards for a few stitches to lock the start and end of a seam
Foot control or treadle	starts the machine and controls its speed

EREX FASHION TV: the main parts of a sewing machine and what each does. As you watch, find each part from Figure 1 on the machine in the video; on a different model the parts may sit in slightly different places.

Worked example

Worked example 1: following one stitch. Describe what the parts do while a machine makes a single lockstitch.

The needle goes down through the fabric, carrying the top thread.
As the needle starts to rise, the top thread forms a small loop under the needle plate. The turning hook catches the loop and carries it round the bobbin case, so the loop goes round the bobbin thread.
The take-up lever rises and pulls the loop up, locking the two threads together inside the fabric.
The feed dogs rise, grip the fabric under the presser foot and move it back by one stitch length; then the cycle repeats.

Worked example

Worked example 2: choosing a machine. A women's cooperative in a village without a steady electricity supply wants to start making school uniforms. Which type of machine should they buy, and why?

Electric and computerised machines need a steady electricity supply, so they would often stand idle.
A hand machine is cheap but slow, and leaves only one hand to guide the fabric: too slow for uniforms.
A treadle machine needs no electricity, leaves both hands free, sews uniforms' cotton and polyester-cotton well, and can be repaired locally.
Answer: treadle machines, with an overlocker added later if a generator or solar power becomes available, to neaten seams faster.

Warning

Common mistake. Turning the hand wheel away from you can tangle the thread round the hook and jam the machine. Always turn it towards you. Before threading, changing the needle or cleaning, switch off and unplug an electric machine, or take your feet off the treadle.

Tip

Memory hook: follow the thread. Learn the parts in the order the thread meets them: spool pin, guide, tension, take-up lever, guides, needle; then from below: bobbin, bobbin case, hook.

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Practice

Name four types of sewing machine and say how each is driven.
State the function of (a) the feed dogs, (b) the take-up lever, (c) the presser foot.
What is a lockstitch, and which two threads form it?
Why should the hand wheel always be turned towards you?
Give two advantages of a sewing machine over hand sewing.
A seam keeps coming undone at both ends. Which part of the machine should the sewer use, and how?
A tailor is choosing between a second-hand treadle machine and a new computerised one for a small shop in a town with frequent power cuts. Compare the two and recommend one.

Show answersHide answers

Hand machine (handle turned by hand); treadle machine (foot plate rocked by the feet); electric machine (motor and foot pedal); computerised machine (motor controlled by a computer); industrial machine (powerful motor under a table). Any four.
(a) Move the fabric under the needle one stitch length at a time. (b) Pulls each stitch tight and draws thread from the reel for the next stitch. (c) Holds the fabric flat against the feed dogs.
A stitch in which the top (needle) thread and the lower (bobbin) thread lock together between the layers of fabric.
Turning it away from you can tangle the thread round the hook and jam the machine.
It is much faster; the stitches are even, small and strong; it can make special stitches such as zigzag (any two).
The reverse lever: sew forward 3 or 4 stitches, hold the lever to sew back over them, then sew forward again; do the same at the end of the seam.
The treadle machine works during power cuts, is cheap and easy to repair, but offers only straight stitch (or limited stitches). The computerised machine is fast and offers buttonholes and many stitches, but stops when the power goes and is costly to repair. For a town with frequent power cuts, the treadle is the safer main machine; a computerised one could be added later for decorative work.

Sources and credits

Lesson text, Figure 1, tables, worked examples and practice: written by Ganzaa.
Photo: Atelier de couture en plein centre ville, Alex Epoh, Wikimedia Commons, CC BY-SA 4.0.
Photo: Neighbourhood seamstress, Ndiwulira, Wikimedia Commons, CC BY-SA 4.0.
Video: Sewing Machine Parts Explained for Beginners (Easy & Quick), EREX FASHION TV, embedded from YouTube.

1Types of sewing machine

2The parts and what they do

Types of sewing machine

The parts and what they do