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Maharashtra SSC Apparel Sewing Machine Operator Pre-Voc/NSQF study materials
Maharashtra SSC Apparel Sewing Machine Operator Pre-Voc/NSQF study resources

Maharashtra SSC Apparel Sewing Machine Operator Pre-Voc/NSQF practice questions

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Question 1Workplace safety, health and hygiene

On a single-needle lockstitch machine, what is the main job of the metal needle guard mounted close to the needle bar?

  1. It clamps the needle tightly inside the needle bar
  2. It stops the fabric plies from sliding apart
  3. It guides the upper thread down to the needle eye
  4. It keeps fingers away from the moving needle Correct answer.

Explanation

The needle guard is a fixed barrier set a few millimetres from the needle path, so a finger that slips towards the needle strikes metal instead of the point. It does not tension thread, hold the needle or control the fabric; those jobs belong to the tension discs, the needle clamp screw and the presser foot. A bent, loose or missing guard must be reported and replaced before the machine is run again.

Question 2Workplace safety, health and hygiene

Why should a sewing operator wash their hands with soap after using the toilet and before touching fabric again?

  1. To keep the machine oil from turning rancid
  2. To reduce static electricity on the fabric
  3. To remove germs and soil that stain the cloth Correct answer.
  4. To stop the feed dog from clogging with lint

Explanation

Hands carry germs and body oils that pass easily onto light-coloured fabric, leaving stains and creating a health risk for the next person who handles the garment. Washing with soap and running water and then drying the hands is a basic personal hygiene rule in every garment unit. Machine oil, lint build-up and static are not affected by washing the hands.

Question 3Workplace safety, health and hygiene

An operator uses compressed air to blow lint off a sewing machine. Which PPE is worn specifically to protect the eyes from flying particles?

  1. Cotton hand gloves
  2. Foam ear plugs
  3. Steel-toe safety shoes
  4. Impact-rated safety goggles Correct answer.

Explanation

Compressed air can lift lint, metal chips and broken needle fragments and drive them into the eye at speed, so impact-rated goggles that seal around the eye are needed. Gloves, ear plugs and safety shoes protect the hands, hearing and feet rather than the eyes. Air pressure should also be kept low and the jet directed away from the operator and other workers.

Question 4Workplace safety, health and hygiene

While oiling the machine, an operator finds the motor cable is frayed and the inner wires are visible. What is the correct action?

  1. Wrap the frayed part with insulation tape and finish the shift
  2. Ask a co-worker to stand guard over the cable till closing
  3. Switch off at the mains, tag the machine and report it Correct answer.
  4. Hold the cable away from the table and keep sewing slowly

Explanation

A frayed cable with exposed conductors can give a fatal shock, especially where the floor is damp or the operator's hands are oily. The machine must be isolated at the mains, tagged out of service and reported so a qualified person can fit a new cable. Tape is not a repair, and holding or guarding a live cable does not remove the danger.

Question 5Workplace safety, health and hygiene

A machinist complains of neck and shoulder pain after long shifts. Which workstation change is most likely to reduce the strain?

  1. Set the chair and table so the forearms stay level Correct answer.
  2. Bend forward over the needle so the stitch line stays in view
  3. Raise the chair until the feet hang clear of the floor
  4. Stand at the machine for the whole shift instead of sitting

Explanation

Neck and shoulder pain usually comes from a table that is too high or too far away, which forces the operator to hunch and reach forward. The chair should be set so the feet rest flat, the knees are about hip height and the elbows are near a right angle, keeping the shoulders relaxed and the work close to the body. Short stretch breaks during the shift also help.

Question 6Workplace safety, health and hygiene

Lint packed around a hot motor catches fire during a shift. What should the operator do first?

  1. Fan the flame with a cloth until it goes out
  2. Throw a bucket of water over the motor to cool it
  3. Finish the batch first and report at the end of the shift
  4. Cut power, raise the alarm, use CO2 Correct answer.

Explanation

An electrical fire needs the power cut first, otherwise the live circuit keeps feeding the flame; carbon dioxide or dry powder extinguishers are suitable because they do not conduct electricity. Water conducts electricity and can send a shock back to the operator, while fanning supplies more oxygen and spreads burning lint. The alarm must be raised immediately, and only trained staff should attempt to fight a small fire.

Question 7Workplace safety, health and hygiene

A puddle of machine oil has formed on the floor beneath a sewing table. What is the correct housekeeping response?

  1. Wash the floor with a bucket of water and leave it wet
  2. Wipe it up and bin oily rags in a covered tin Correct answer.
  3. Leave the puddle to dry because oil evaporates quickly
  4. Spread fabric scraps over the puddle and carry on sewing

Explanation

Oil on a smooth floor causes slips and falls, and oily rags left in the open add to the fire load of the section. The spill should be cleaned up at once with an absorbent, the used rags kept in a covered metal container, and the leak traced so it does not happen again. Water spreads oil instead of removing it, and machine oil does not evaporate quickly in a workshop.

Question 8Workplace safety, health and hygiene

A mechanic needs to remove the belt guard of a sewing machine to change the belt. What must be done before the guard is opened?

  1. Ask another operator to hold the guard open during the repair
  2. Isolate and lock the power, then prove the machine is dead Correct answer.
  3. Switch off only the machine lamp and begin the repair
  4. Slow the machine to its lowest speed and keep it running

Explanation

Guards are removed only under lockout and tagout: the supply is switched off, the isolator is locked and the machine is proved dead so nobody can restart it while hands are inside the belt area. A machine left running, even at low speed, or a guard held open by a helper, can start unexpectedly and cause serious injury. The lock key stays with the person carrying out the repair.

Question 9Workplace safety, health and hygiene

Why is local exhaust ventilation installed at fabric-cutting and sewing points that generate fine lint?

  1. To keep the fabric from stretching as it is stitched
  2. To press the creases out of fabric before cutting
  3. To cool the sewing machine motor on long shifts
  4. To trap airborne fibre dust before it is breathed in Correct answer.

Explanation

Fine fibre dust from cutting and high-speed sewing stays airborne for a long time and can reach deep into the lungs, so extraction hoods are placed close to the source to capture it before it enters the operator's breathing zone. The same dust settles on hot motors and adds to the fire risk, which is why regular cleaning of the section matters too. Ventilation does not control stitch quality, fabric stretch or creasing.

Question 10Workplace safety, health and hygiene

A needle pierces an operator's finger and the wound is bleeding. What is the correct first-aid sequence?

  1. Wash with solvent, apply cotton waste and keep sewing
  2. Suck the wound, apply grease and go back to the machine
  3. Bandage it tightly over the glove and finish the shift
  4. Let it bleed, wash with soap, cover and report Correct answer.

Explanation

A needle-stick is a puncture wound that can push oil, dye or blood into the tissue, so it should be allowed to bleed briefly, washed with clean running water and soap, dried and covered with a waterproof dressing. Every injury must be entered in the accident register so that tetanus cover and further treatment can be checked. Grease, solvent or cotton waste in the wound increases the risk of infection and is never first aid.

Question 11Workplace safety, health and hygiene

In the stitching section of a garment unit, a sign outside a cabinet is painted red. Under the standard safety colour code used in Indian workplaces, what does red identify?

  1. Red identifies mandatory signs such as 'wear eye protection'.
  2. Red identifies the edges of walkways and stair treads.
  3. Red identifies first-aid boxes and stretcher locations.
  4. Red identifies fire-fighting equipment and the place where it is kept. Correct answer.

Explanation

In the standard workplace safety colour code, red is reserved for fire protection: extinguishers, hose reels, alarms and the cabinets or points where they are kept. Green marks first aid and escape routes, blue marks mandatory instructions and yellow marks caution and walkway edges.

Question 12Workplace safety, health and hygiene

An operator keeps an open tiffin box on the sewing table and eats snacks while the machine is running. Why is this practice a health and safety problem in a garment unit?

  1. The tiffin box blocks light from reaching the needle plate.
  2. Food smells weaken the polyester thread spools stored on the rack.
  3. Food crumbs and spills attract pests and soil the fabric, and eating while stitching divides attention near a moving needle. Correct answer.
  4. Eating at the machine reduces the stitch speed and lowers daily output.

Explanation

Factory hygiene rules require eating only in the designated canteen or rest area, because food waste attracts insects and rodents that contaminate garments. Eating while operating a lockstitch machine is also unsafe, since the operator's hands and eyes are needed at the needle point.

Question 13Workplace safety, health and hygiene

Bundles of cut fabric have been stacked in front of the marked emergency exit of the stitching line. What is the correct response?

  1. Move them aside only after the fire alarm sounds.
  2. Leave them, because the exit is only needed during a fire drill.
  3. Shift the bundles immediately to the storage rack and keep the exit route clear at all times. Correct answer.
  4. Throw a tarpaulin over them so that the exit sign stays visible.

Explanation

Escape routes and exits must stay clear of obstruction at every moment, because smoke and panic during a real fire leave no time to clear a blocked doorway. Stacked fabric is also highly combustible, so storing it against an exit adds fuel next to the escape route.

Question 14Workplace safety, health and hygiene

A small fire starts inside the electric motor of a sewing machine that is still plugged into the mains. Which fire-fighting equipment is suitable for this fire?

  1. A water-type extinguisher, because water cools the burning motor quickly.
  2. A foam extinguisher, because the foam blanket smothers the flames.
  3. A carbon dioxide extinguisher, because the gas does not conduct electricity and leaves no residue. Correct answer.
  4. A bucket of water poured directly into the motor housing.

Explanation

Fires involving live electrical equipment are class E fires in Indian practice, and carbon dioxide is the standard choice because it is non-conductive and evaporates without damaging the motor. Water and foam both conduct electricity and expose the operator to shock, so they must never be used on energised equipment.

Question 15Workplace safety, health and hygiene

A 25 kg roll of fabric has to be moved from the floor onto the cutting table. Which technique protects the operator's back?

  1. Lift the roll with straight legs and a rounded back so the back muscles do the work.
  2. Twist the trunk while lifting so the roll lands on the table in one movement.
  3. Bend at the waist, hold the roll at arm's length and lift it quickly.
  4. Bend the knees, hold the roll close to the body and lift by straightening the legs while keeping the back straight. Correct answer.

Explanation

Heavy rolls should be lifted with the leg muscles, keeping the load close to the body and the back straight, because the further the load is from the spine the greater the strain on the lower back. Twisting or jerking during a lift sharply increases the risk of a disc or muscle injury.

Question 16Workplace safety, health and hygiene

Noise in the overlock section measures about 92 dB(A) and operators have to shout to be heard. What is the correct health response by the unit?

  1. Rotate operators to quieter sections only after they report hearing loss.
  2. Take no action, because 92 dB(A) is below the level at which hearing is affected.
  3. Ask operators to speak louder so that they become used to the noise.
  4. Provide hearing protection such as earplugs, train operators to fit and wear them correctly, and mark the area as a hearing-protection zone. Correct answer.

Explanation

Hearing damage begins at average exposure around 85 dB(A), so a measured 92 dB(A) requires action: hearing protection must be issued and worn correctly, and the area must be marked so that everyone entering uses protection. Noise should also be reduced at source or by enclosure wherever practical.

Question 17Workplace safety, health and hygiene

An operator is asked to remove an oil stain from a finished garment using a solvent-based spot remover. Which working practice protects the operator's health?

  1. Use bare hands but wash them with the solvent afterwards to remove the chemical.
  2. Decant the solvent into an unlabelled bottle so it is easy to carry to the table.
  3. Store the solvent in a soft-drink bottle beside the machine so it is within reach.
  4. Read the container label and the safety data sheet, wear the recommended gloves, and use the solvent only where ventilation is adequate. Correct answer.

Explanation

Solvent spot removers can damage skin, eyes and the respiratory tract, so the label and safety data sheet must be read before use and the specified gloves worn. The work must be done in a ventilated place, and chemicals must never be transferred into unlabelled or food-type containers where someone could drink them by mistake.

Question 18Workplace safety, health and hygiene

A helper in the stitching room is gripping a machine frame and cannot let go because of an electric shock. What should the operator do first?

  1. Wait for the helper to release the frame and then give first aid.
  2. Throw water on the machine to break the current.
  3. Pull the helper away by the arm as fast as possible.
  4. Switch off the main supply or pull the plug, and only then touch the helper. Correct answer.

Explanation

A person in contact with a live conductor becomes part of the circuit, so anyone who touches them is likely to be shocked as well. The supply must be isolated at the switch or plug first; only after the current is cut should the helper be moved and first aid or CPR started.

Question 19Workplace safety, health and hygiene

Why must the metal frame and motor body of a sewing machine be bonded to earth through the three-pin plug?

  1. If a live wire touches the metal body, the earth gives a low-resistance path so the current trips the circuit breaker instead of passing through the operator. Correct answer.
  2. The earth connection keeps the table free of static electricity from the fabric.
  3. The earth connection reduces the running noise of the motor.
  4. The earth connection keeps the stitch length steady when the machine runs at high speed.

Explanation

Earthing provides a low-resistance path back to the supply so that a fault current is large enough to operate the fuse or circuit breaker within a fraction of a second. Without it, a live metal frame stays energised and the operator's body becomes the path to earth.

Question 20Workplace safety, health and hygiene

A unit wants to cut down needle-prick injuries among operators who trim threads and handle needles by hand. Applying the hierarchy of controls, which measure gives the most reliable protection?

  1. Retrain all operators in careful needle handling once a year.
  2. Issue a box of disposable gloves to every operator.
  3. Display a warning poster about needle injuries beside every machine.
  4. Fit guarded mechanical thread trimmers so hands stay away from the needle point, and provide a lidded needle-disposal box at each workstation. Correct answer.

Explanation

The hierarchy of controls ranks elimination and engineering controls above administrative measures and PPE, because guards work without depending on human behaviour. A mechanical trimmer keeps hands away from the needle every cycle, whereas a poster, training or gloves rely on the operator remembering and complying.

Question 21Sewing machine parts, setup and basic maintenance

On a lockstitch sewing machine, the presser foot is mainly used to:

  1. pull the bobbin thread up through the needle plate
  2. hold the fabric firmly against the needle plate and feed dog Correct answer.
  3. cut the thread chain after the seam is finished
  4. control the tension of the upper thread

Explanation

The presser foot applies controlled downward pressure so the fabric stays in contact with the feed dog and moves evenly. Upper thread tension is set by the tension discs, and thread trimming is done by a separate cutter.

Question 22Sewing machine parts, setup and basic maintenance

Before removing lint and fabric dust from the feed dog area of a power-operated lockstitch machine, the operator should first:

  1. raise the presser foot and continue pedalling slowly
  2. apply oil to the bobbin case
  3. remove the needle plate with the machine running
  4. switch off the machine and disconnect it from the power supply Correct answer.

Explanation

Cleaning near the needle, feed dog and bobbin case puts the hands close to moving parts. The safe routine is to switch off and unplug the machine, then remove the needle plate and brush out lint. This prevents accidental starting.

Question 23Sewing machine parts, setup and basic maintenance

The stitch length regulator on a lockstitch machine controls:

  1. the clearance between the needle and the rotary hook
  2. the pressure of the presser foot on the fabric
  3. the amount of thread wound on the bobbin
  4. the distance the feed dog advances the fabric per stitch Correct answer.

Explanation

Stitch length is the distance the fabric is fed between two needle penetrations. Adjusting the regulator changes how far the feed dog moves per stitch, so a higher setting gives a longer stitch. Presser foot pressure and hook clearance are set separately.

Question 24Sewing machine parts, setup and basic maintenance

Upper thread looping and bunching on the underside of a seam usually indicates that:

  1. the upper thread tension is too loose Correct answer.
  2. the bobbin case has been removed
  3. the needle is too large for the fabric
  4. the bobbin tension is too loose

Explanation

When upper tension is too loose, the needle thread is not held back and lies on the underside of the fabric, forming loops. The remedy is to increase upper tension in small steps and check the balance on a scrap. Loose bobbin tension produces the opposite fault, with bobbin thread pulled to the top.

Question 25Sewing machine parts, setup and basic maintenance

On a lockstitch machine, the fabric does not move forward although the needle goes up and down and the feed dog is moving. Which adjustment is most likely to be the cause?

  1. upper thread tension is too high
  2. presser foot pressure is too light Correct answer.
  3. the bobbin is nearly empty
  4. stitch length is set too short

Explanation

The feed dog can only move fabric that is pressed against it. If presser foot pressure is too light, the fabric slips and stays in place while the feed dog moves underneath. Increasing the pressure slightly should restore feeding; stitch length and thread tension do not create this grip.

Question 26Sewing machine parts, setup and basic maintenance

For sewing heavy denim with a standard lockstitch machine, the most suitable needle choice is:

  1. a twin needle with a small needle distance
  2. a size 9/65 needle with a sharp point
  3. a size 16/100 or 18/110 needle with a sharp or light ball point Correct answer.
  4. a size 11/75 ball point needle of the kind normally used for light knit fabrics

Explanation

Heavy, tightly woven fabric such as denim needs a stronger needle that will not bend or break, so a larger size in the 16/100 to 18/110 range is used. A sharp point helps penetrate the dense weave. Small size 9/65 or 11/75 needles are for lightweight fabrics and may deflect or break.

Question 27Sewing machine parts, setup and basic maintenance

While winding a bobbin, the thread should be guided:

  1. around the hand wheel twice to increase tension before winding
  2. through the bobbin winder tension guide and evenly across the bobbin Correct answer.
  3. loosely by hand so that it crosses itself on the bobbin
  4. through the eye of the needle before winding

Explanation

The bobbin winder has a tension guide and a level-winding mechanism. The thread must pass through the guide and wind evenly from side to side so the bobbin is firm and level; an uneven or loose bobbin causes poor lower tension. The needle is not threaded during bobbin winding, and thread is never wrapped around the hand wheel.

Question 28Sewing machine parts, setup and basic maintenance

Which of these is the correct routine for lubricating a lockstitch machine?

  1. oil only the needle and the fabric contact area
  2. use any available automotive oil on all moving parts and bearings of the machine
  3. apply a few drops of recommended sewing machine oil to the oil points, then run the machine briefly Correct answer.
  4. fill the oil reservoir to the top before every shift so that no oiling is needed during work

Explanation

The manufacturer marks oil holes and reservoirs for the machine; a few drops of the specified sewing machine oil at those points is enough. Running the machine briefly spreads the oil. Overfilling, using the wrong oil, or oiling the needle and fabric path can stain fabric and attract lint.

Question 29Sewing machine parts, setup and basic maintenance

The rotary hook of a lockstitch machine is correctly timed when:

  1. the hook point reaches the needle scarf just as the needle starts to rise from its lowest position Correct answer.
  2. the hook point passes the needle when the needle is at its highest point
  3. the needle eye is below the needle plate when the hook point passes the scarf
  4. the hook point touches the needle at the top of the stroke and pushes it slightly sideways during every revolution

Explanation

Correct hook timing means the point meets the needle scarf slightly after bottom dead centre, when the needle has begun to rise and a small loop of needle thread has formed. If the hook is too early or too late, it misses the loop and stitches skip. Hook clearance should be about 0.05 to 0.1 mm without touching the needle.

Question 30Sewing machine parts, setup and basic maintenance

A lockstitch machine produces skipped stitches on a medium cotton fabric. The needle is new and the correct size, threading is correct, and the bobbin is wound evenly. Which combination of causes should be checked first?

  1. bobbin case latch broken, bobbin case removed, and feed dog set too high above the plate
  2. needle inserted the wrong way, bent needle, or incorrect needle bar height Correct answer.
  3. presser foot pressure too heavy and stitch length too short
  4. stitch length too long and reverse lever engaged

Explanation

Once threading and bobbin winding are ruled out, skipped stitches most often come from the needle-to-hook relationship. A needle set back to front, a slightly bent needle, or a needle bar set too high or too low can make the hook miss the loop. These should be checked with the machine switched off.

Question 31Sewing machine parts, setup and basic maintenance

On a lockstitch machine, the needle plate (throat plate) mainly:

  1. holds the bobbin inside the machine and controls the lower thread tension
  2. pulls the upper thread tight after every stitch
  3. supports the fabric around the needle and has a needle hole Correct answer.
  4. sets the stitch length by moving the feed dog

Explanation

The needle plate is the flat metal plate under the needle. It supports the fabric as the needle enters and has a small hole through which the needle and thread pass.

Question 32Sewing machine parts, setup and basic maintenance

Which part of a lockstitch machine lifts the upper thread and pulls it tight to lock each stitch?

  1. the feed dog
  2. the presser foot
  3. the take-up lever Correct answer.
  4. the bobbin winder

Explanation

The take-up lever moves up and down with the needle bar. It pulls the upper thread from the spool and tightens the interlaced stitch.

Question 33Sewing machine parts, setup and basic maintenance

A sewing machine needle is found to be bent. The correct action is to:

  1. oil it and continue sewing
  2. use it only on thin fabric for light work
  3. straighten it carefully with pliers and continue using it
  4. replace it with a new needle of the same size Correct answer.

Explanation

A bent needle cannot be straightened reliably. It can hit the needle plate or hook, causing skipped stitches or damage, so it should be replaced with a new needle of the same size.

Question 34Sewing machine parts, setup and basic maintenance

On a lockstitch machine, the pressure of the presser foot on the fabric is set by:

  1. the upper thread tension dial
  2. the bobbin case tension screw
  3. the stitch length dial located on the machine front
  4. the presser foot pressure regulating screw Correct answer.

Explanation

Presser foot pressure is adjusted with the pressure regulating screw or knob on the machine head. It controls how firmly the foot holds the fabric against the feed dog.

Question 35Sewing machine parts, setup and basic maintenance

A lockstitch machine motor runs, but the needle bar does not move and a knocking sound is heard. The most likely cause is:

  1. an empty bobbin
  2. a tight upper thread
  3. a blunt needle
  4. a loose or broken drive belt Correct answer.

Explanation

If the motor turns but the needle bar stays still and a knocking noise is heard, the drive belt may be loose, slipping, or broken. The belt should be checked and adjusted or replaced.

Question 36Sewing machine parts, setup and basic maintenance

Which oil is suitable for routine lubrication of a lockstitch machine?

  1. any lubricant available in the workshop
  2. cooking oil from the kitchen
  3. thick engine grease
  4. light clear sewing machine oil Correct answer.

Explanation

A lockstitch machine should be oiled with light clear sewing machine oil. It lubricates moving parts without gumming them, and only a few drops are needed at the marked oil points.

Question 37Sewing machine parts, setup and basic maintenance

To increase the tension on the bobbin thread, the small tension screw on the bobbin case is turned:

  1. half a turn anticlockwise
  2. clockwise in small steps Correct answer.
  3. with the machine running at full speed
  4. fully out of the case

Explanation

The small screw on the bobbin case adjusts the spring that presses on the bobbin thread. Turning it clockwise increases the tension; turn it in small steps and test the stitch.

Question 38Sewing machine parts, setup and basic maintenance

When the feed dog drop lever is used to lower the feed dogs, the machine is being set up for:

  1. automatic bobbin winding
  2. darning or free-motion embroidery Correct answer.
  3. normal straight stitching on cotton
  4. heavy denim seams with long stitches

Explanation

Lowering the feed dogs stops the machine from moving the fabric forward. The operator then guides the fabric freely, which is needed for darning and free-motion embroidery.

Question 39Sewing machine parts, setup and basic maintenance

After refitting the bobbin case, the operator finds that the bobbin case falls out when the thread is pulled. The most likely reason is:

  1. the bobbin case is not seated correctly Correct answer.
  2. the feed dog height is set too low
  3. the upper thread tension is too loose
  4. the needle is too fine for the fabric

Explanation

The bobbin case must click into its seat so the latch holds it in place. If it is not fully seated, the case can fall out when the thread is pulled or the machine starts.

Question 40Sewing machine parts, setup and basic maintenance

A motor belt on a lockstitch machine is adjusted much too tight. The most likely result is:

  1. the motor and bearings overheat and wear faster Correct answer.
  2. the needle plate works loose on the bed
  3. the stitch length becomes longer than set
  4. the bobbin winds with uneven thread

Explanation

A belt that is too tight puts extra load on the motor and shaft bearings. This causes overheating, noise, and faster wear, so the belt should have the recommended slack.

Question 41Sewing machine parts, setup and basic maintenance

On a sewing machine needle marked 80/12, the figure 80 indicates the needle's:

  1. point style that suits the fabric being sewn
  2. overall length of the needle measured in millimetres
  3. size of the thread that the machine has been set for
  4. blade diameter in hundredths of a millimetre Correct answer.

Explanation

Metric needle sizes give the blade diameter in hundredths of a millimetre, so a size 80 needle measures 0.80 mm across the blade. The second figure, 12, is the equivalent older Singer size. Heavier fabric and thicker thread call for a larger metric number.

Question 42Sewing machine parts, setup and basic maintenance

The small finger projecting from a lockstitch bobbin case sits in a notch in the shuttle race body. Its function is to:

  1. guide the needle thread into the tension discs
  2. keep the feed dog timing constant
  3. stop the bobbin case from turning with the hook Correct answer.
  4. hold the bobbin against the winder wheel

Explanation

The positioning finger locates the bobbin case in the shuttle race and prevents it rotating while the hook turns around it. If the finger is not seated in its notch, the case can spin, the thread jams and the case may even be thrown out.

Question 43Sewing machine parts, setup and basic maintenance

Before winding a bobbin with the built-in bobbin winder of a lockstitch machine, the operator must release the:

  1. upper thread tension discs
  2. feed dog drop lever
  3. handwheel clutch Correct answer.
  4. presser foot pressure screw

Explanation

Releasing the handwheel clutch separates the wheel from the main shaft, so the bobbin winder turns while the needle bar and feed remain still. If the clutch stays engaged, the needle keeps stitching while the bobbin is being wound, which is unsafe and gives an uneven wind.

Question 44Sewing machine parts, setup and basic maintenance

When threading the upper thread on a lockstitch machine, the presser foot should be kept raised because:

  1. the tension discs open so the thread seats between them Correct answer.
  2. the feed dogs then drop below the needle plate surface
  3. the needle thread can then pass behind the needle bar
  4. the take-up lever then rests at its lowest point of travel

Explanation

Raising the presser foot removes the spring load from the tension discs, so they open and the thread can drop fully between them. If the foot is down, the discs stay closed and the thread may sit on top of them, giving loose stitches and poor loop formation.

Question 45Sewing machine parts, setup and basic maintenance

At its highest point, the feed dog of a correctly set lockstitch machine should:

  1. stand about 5 mm clear above the needle plate
  2. rise just above the needle plate surface Correct answer.
  3. stay completely below the top of the needle plate
  4. sit level with the bottom edge of the bobbin case

Explanation

The teeth should come just above the plate, roughly 0.8 to 1 mm at the highest point, so they grip the fabric without lifting it. Set too high, the feed dog puckers the seam and can damage the needle; set too low, the fabric slips and does not advance.

Question 46Sewing machine parts, setup and basic maintenance

After oiling the hook and other oiling points of a lockstitch machine, the operator should, before starting production:

  1. fill the bobbin case with oil to keep the hook lubricated
  2. loosen the needle clamp screw to let the oil drain out
  3. wipe the machine with a wet cloth and start sewing at once
  4. stitch on scrap fabric to flush out surplus oil Correct answer.

Explanation

Fresh oil and loosened dirt work out of the oiling points during the first few stitches. Stitching a scrap first carries this surplus away instead of staining the garment. Oil is applied sparingly at the specified points, not poured into the bobbin case.

Question 47Sewing machine parts, setup and basic maintenance

On an industrial lockstitch machine, the knee lifter is mainly used to:

  1. raise the presser foot with both hands free Correct answer.
  2. stop the machine instantly in an emergency
  3. lower the feed dogs for free-motion sewing
  4. change the stitch length while the machine is running

Explanation

The knee lifter is a lever pushed by the knee that raises the presser foot, so the operator can position, turn or remove the work while both hands stay on the fabric. It has no connection with stitch length, braking or the feed dog drop mechanism.

Question 48Sewing machine parts, setup and basic maintenance

The presser foot pressure on a lockstitch machine is set far too high for a light georgette fabric. The most likely result is:

  1. the feed dog cannot grip and the fabric does not move
  2. the stitch length becomes longer than the setting
  3. the fabric is marked, puckered and dragged unevenly Correct answer.
  4. the bobbin thread is pulled up to the fabric face

Explanation

Excessive pressure flattens the fabric, leaves feed-dog marks and makes the plies feed unevenly, so light fabric should be sewn with reduced pressure. With too little pressure the fabric would slip and fail to move forward, which is the opposite fault.

Question 49Sewing machine parts, setup and basic maintenance

A needle plate whose needle hole is much larger than the needle is left on the machine while light cotton is sewn. The most likely problem is:

  1. the stitch length changes as soon as the plate is fitted
  2. fabric is pushed into the hole and the stitch jams Correct answer.
  3. the bobbin thread tension becomes much too tight
  4. the seam wanders away from the seam guide line

Explanation

The needle hole should be only slightly larger than the needle in use. With an oversized hole the needle pushes soft fabric down into it, causing jams, skipped stitches and bent or broken needles, so the plate is matched to the needle and fabric.

Question 50Sewing machine parts, setup and basic maintenance

While sewing at high speed, the stitch length on a lockstitch machine gradually changes although the regulator lever has not been touched. The most likely cause is:

  1. the stitch regulator lever is loose and creeps Correct answer.
  2. the bobbin has been wound with too much thread
  3. the tension discs are worn and release the thread early
  4. the needle is too fine for the fabric being sewn

Explanation

The stitch length regulator is held by friction and a locking arrangement, so a loose lever or worn linkage can creep under vibration at speed and alter the setting. The lever and its connection should be checked and tightened before production continues.