Maintaining a sewing machine and correcting faults

24 min

Let's begin

A school's sewing room has a machine that "does not work": it runs heavily, skips stitches and snaps its thread. A technician opens the needle plate and pulls out a grey pad of fluff as thick as a finger, packed between the feed dogs. Under it the hook is dry, and the needle is bent. Twenty minutes of cleaning, a drop of oil and a new needle, and the machine sews perfectly again. Most sewing-machine "breakdowns" are really missed maintenance. This lesson shows the routine care a machine needs, and how to find and correct the common faults yourself.

Definition

Maintenance: the regular care that keeps a machine working well and makes it last: cleaning, oiling, replacing worn parts such as needles, and storing it properly.

Lint: the fine fluff of fibres that fabric and thread shed while sewing; it collects round the feed dogs and the hook.

Thread tension: how tightly each thread is held as the stitch forms. In a balanced stitch the two threads lock between the layers of fabric, and the stitch looks the same on both sides.

Routine care

When	What to do
Every time you finish	raise the needle, lower the presser foot onto a scrap of fabric, switch off and unplug; brush away lint; wipe the machine; put on the dust cover
After every 6–8 hours of sewing, or each new project	fit a new needle; a blunt or bent needle causes skipped stitches and broken thread
Weekly in a busy sewing room	remove the needle plate and bobbin case; brush the lint from the feed dogs, hook and bobbin area; oil the points shown in the manual
Treadle machines	also check the leather belt for wear and the right tightness; oil the joints of the treadle and the wheel
Once a year	a full service by a sewing-machine technician

Cleaning and oiling

Unplug the machine. Remove the needle, the presser foot and the needle plate (usually one or two screws).
Take out the bobbin and the bobbin case. Brush lint from the feed dogs, the hook and the case with a small, stiff brush. Do not blow into the machine: breath is damp and pushes lint further in.
Put one drop of sewing-machine oil on each point marked in the manual, often the hook race. Use only sewing-machine oil: cooking oil and engine oil turn sticky and attract dirt. Some modern machines must not be oiled at all; the manual says so.
Refit the parts, turn the hand wheel a few times to spread the oil, then sew on a scrap of fabric to soak up any extra oil before you sew a garment.

Changing the needle

Unplug the machine and turn the hand wheel to raise the needle to its highest point. Loosen the needle clamp screw and pull the old needle down. On most domestic machines the new needle goes in with its flat side to the back. Push it up as far as it will go and tighten the screw firmly. Put used needles in a closed container, never loose in the bin.

Gluetopia: basic sewing machine maintenance, cleaning out the lint and oiling the machine. Notice how much lint comes out from under the needle plate, and that only a drop of oil goes on each point. Always follow the manual for your own machine.

Finding and correcting faults

Fault	Likely causes	Remedy
Top thread breaks	threaded wrongly; top tension too tight; bent, blunt or wrong-size needle; poor thread	rethread with the foot up; loosen the tension a little; fit a new needle of the right size; use good thread
Bobbin thread breaks	bobbin wound unevenly or too full; bobbin in the case the wrong way; lint in the case	rewind it; reinsert as the manual shows; clean the case
Skipped stitches	bent or blunt needle; needle the wrong way round or not pushed fully up; wrong type of needle (e.g. an ordinary needle on jersey)	fit a new needle correctly; use a ballpoint needle for knits
Loops under the fabric	top thread not between the tension discs; top tension too loose	rethread with the presser foot up; tighten the top tension
Seam puckers	tension too tight; stitch too long for fine fabric; blunt needle; fabric pulled	loosen tension; shorten the stitch; new fine needle; guide, do not pull
Needle breaks	sewing over pins; pulling the fabric; needle too fine for thick fabric; loose needle clamp	remove pins before the foot; guide gently; use a thicker needle; tighten the clamp
Fabric does not move	presser foot not lowered; stitch length at 0; feed dogs lowered; lint packed in the feed dogs	lower the foot; set the stitch length; raise the feed dogs; clean
Machine runs heavily or noisily	lint and old oil; no oil; thread wound round the hook	clean, remove the thread, oil as the manual says

Worked example

Worked example 1: reading a tension sample. On a test seam, small blue dots of bobbin thread show on the top of the fabric, and the seam puckers slightly. What is wrong and what should be done?

The bobbin thread is being pulled up to the top surface, so the locks are forming on top (Figure 4, middle).
This means the top tension is too tight; the puckering agrees.
Check the threading first. Then turn the top tension dial to a lower number, one step at a time, testing on a scrap each time, until the locks sit between the layers.

Worked example

Worked example 2: planning needles for a term. A school has 10 machines. Each is used for 4 hours a week for a 12-week term, and a needle is changed after about 8 hours of sewing. How many needles are needed?

Hours per machine: $4 \times 12 = 48$ hours.
Needles per machine: $\frac{48}{8} = 6$ .
For 10 machines: $6 \times 10 = 60$ needles. Add spares for breakages, say 10 to 15 more.

Warning

Safety during maintenance. Always unplug an electric machine before cleaning, oiling, opening covers or changing the needle or bulb; a foot resting on the pedal can start it. Keep small screws in a dish so they are not lost or swallowed by small children. Wipe up spilt oil at once, and keep oil off fabric. Never open the motor or wiring yourself; that is a job for a qualified technician.

Tip

Memory hook for faults: "Thread, Needle, Tension, Lint". Check them in that order. Rethreading and a new needle cure most problems before you ever touch the tension dial.

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Practice

Give four things you should do every time you finish using a sewing machine.
Why should you never use cooking oil on a sewing machine?
Which way does the flat side of the needle face on most domestic machines?
What does it mean if the top thread lies in loops on the underside of the fabric?
Give two causes of skipped stitches and the remedy for each.
A sewing class of 8 machines sews 3 hours a week for 10 weeks, with a needle change every 6 hours. How many needles are needed, without spares?
A tailor oils her machine every day with a lot of oil "to keep it smooth", and her customers complain of dark spots on their clothes. Evaluate her practice and advise her.

Show answersHide answers

Raise the needle; lower the presser foot onto a scrap; switch off and unplug; brush away lint; wipe it; cover it (any four).
Cooking oil goes sticky as it dries, collects lint and dirt and clogs the moving parts; only sewing-machine oil should be used.
To the back.
The top tension is too loose, usually because the top thread is not between the tension discs: rethread with the presser foot up, then tighten the top tension if needed.
A bent or blunt needle (fit a new one); a needle inserted the wrong way or not pushed fully up (reinsert it correctly); the wrong needle for the fabric, e.g. on jersey (use a ballpoint needle). Any two.
Hours per machine: $3 \times 10 = 30$ ; needles per machine: $\frac{30}{6} = 5$ ; total $5 \times 8 = 40$ needles.
Too much oil, too often: the extra oil runs onto the fabric and makes dark spots, and it collects lint that clogs the machine. She should oil only the points in the manual, one drop each, after cleaning out lint, and as often as the manual says; then sew on a scrap to absorb extra oil before sewing customers' work.

1Routine care

2Cleaning and oiling

3Changing the needle

4Finding and correcting faults

Routine care

Cleaning and oiling

Changing the needle

Finding and correcting faults