This lab report describes an experiment conducted to study the threading process of an industrial single needle lock stitch sewing machine. The key parts of the machine are identified, including the bobbin winder, pressure foot control, take up lever, thread tension disc, throat plate, and hand wheel. The report outlines the steps to thread both the upper and lower threads, including routing the thread through thread guides and tension mechanisms. The experiment allowed students to learn about the components and threading of a single needle lockstitch machine commonly used in apparel manufacturing.

1. BGMEA UNIVERSITY of FASHION &
TECHONOLOGY
Course code: TEX3204
Course title : Apparel Manufacturing Engineering-
II (Lab)
Lab Report
Experiment no: 05
Experiment name: Study on threading process
of an industrial Single Needle Lock Stitch
(SNLS) (Plain) sewing m/c.
Group-05
Submitted to
Taslima Ahmed Tamanna
Lecturer
BUFT
Submitted by
191-187-801 (Marzia Tarannum)
191-194-801 (Maisha Farzana)
191-503-801 ( Md. Fahim Shakil)

2. 191-187-801
Introduction
The term “single needle stitching”, often found on dress shirt labels, refers to a lockstitch. ...
A lockstitch sewing machine uses two threads, one in the needle and the other in a bobbin.
The motion of the needle and the hook correctly timed, makes each stitch to be locked. A
single needle lock stitch machine is called a plain needle sewing machine. A single needle
lock stitch machine is mostly used as an industrial sewing machine. Modern single needle
lockstitch has a thread trimmer which operates at the highest speed of its kind. Lockstitch
machine is the most commonly used sewing machine in the apparel industry, especially in
woven garments. Sewing thread must possess desirable properties like strength and fineness
to produce neat seam which might enhance longevity of garment. Unmercerized cotton
thread used in sewing of cotton garments produces a solid dyed inconspicuous seam.
Polyester threads purposely enhance the effects in the seams due to their dye uptake
resistance and mercerized cotton threads increase the dye uptake, resulting in darker
appearance in shade. For cotton thread sewn garments meant for dyeing, it is not possible to
switch-off directly from conventional spun polyester or core-spun threads to 100% cotton
threads and retain the same seam characteristics. Equivalent seam strength can be obtained
using heavier cotton threads. Similar degrees of elasticity in seam can be obtained by
increasing stitch density but care must be taken to ensure damage of garment due to it. Seam
pucker resulting from thread shrinkage during garment dyeing can be avoided by slacker
stitches on lock stitch and chain stitch operations.
Objectives
❖ To Know about sewing thread path.
❖ To know about different parts of sewing machine.
❖ To know about threading process for upper and lower thread.
Apparatus
❖ Scissors
❖ Measure Tape
❖ Needles
❖ Pins and Pincushion
❖ Iron and Water Sprayer
❖ Thimble and Threader
❖ Threads
❖ Rulers

3. 191-194-801
Parts of thread path diagram
A single needle lock stitch machine is stitch by one needle of a machine by lock stitch.
1. Bobbin Winder: The bobbin winder is a separate unit screwed on to the
machine, adjacent to the balance wheel. Its function is to wind a reserve of cotton
evenly onto an empty bobbin and (in most cases) spring release when the bobbin
is full.

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2. Pressure Feet Control: It's the part of the machine that pulls the thread from the
spool to feed it through the machine and lifts the thread back up out of the cloth
after a stitch has been made. Simply put, it's the part that goes “up and down” as
anyone sew.
3. Take up Lever: Every sewing machine has a thread take-up lever. It is the arm
carrying the thread at the top of the machine that moves up and down in a narrow,
shaft like opening. The take-up lever is the metal lever (looks like a hook) that is
on top of your machine and moves up and down while you sew. This lever is
what pulls the thread off the spool and helps supply an even feed of thread to
your needle. Once you have rethreaded your machine, start sewing again.
4. Thread tension Disc: Tensions disks control the amount of pressure applied to
the thread for an even feed to the machine needle causing an evenly formed
stitch. Many newer sewing machines have the disks hidden inside the machine
casing. Be sure the machine is threaded correctly. Remember, most tension discs
close when the presser foot is down, so be sure to thread the machine with a
raised foot. A good habit is to put the spool on the machine, and pull out 18
inches of thread.

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5. Thread spring Tension: It comprises of two concave discs put together that
controls the tension of upper thread. By turning it to the right or left, the tension
of upper thread is can be tightened or loosened. The spring in the tension disc
regulates the pressure.
6. Throat plate: This metal plate, sometimes called a needle plate, sits below the
needle and presser foot. A small opening in the plate allows the bobbin thread to
come out and the needle to pass through to make stitches.
7. Stitch Dial: On most modern sewing machines, the stitch length control indicates
the length of a single stitch is in milli metres. So a length of 3.0 means each stitch
is 3mm long (or just under 1/8″). Stitch lengths typically range from 0 to 5, but
can be up to 7, depending on the machine.

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8. Thread Guide: To set up the upper thread for your machine, first place a spool
of thread on your machine's thread pin (also called a spool pin or spool holder).
Thread through the thread guide. Pull the thread to the left of your machine and
thread it through the thread guide. Pull the thread through the U-shaped guide.
9. Back Tack Lever: A backstitch, or backtack, is where you reverse the sewing
machine for a few stitches and sew back over an existing line of stitches.
Backstitching prevents the seam from unraveling and should be done at the start
and end of most seams.

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10. Hand Wheel: The balance wheel, or hand wheel, is the round wheel located at
the upper right of the sewing machine. The balance wheel manually advances the
sewing machine. The balance wheel should only be turned in the direction that
advances the sewing machine—never in the opposite direction.
Threading process for upper thread
1. Turn on the sewing machine.
2. Raise the presser foot lever.

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3. Press needle position button once or twice to raise the needle.
4. Remove the spool cap that is inserted onto the spool pin.
5. Place the spool of thread onto the spool pin. Slide the spool onto the pin so
that the spool is horizontal and the thread unwinds to the front at the bottom.
6. Slide the spool cap onto the spool pin. Slide the spool cap as far as
possible to the right, as shown, with the rounded side on the left.

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7. While holding the thread lightly with your right hand, pull the thread
with your left hand, and then pass the thread behind the thread guide
cover and to the front.
8. Pass the thread under the thread guide cover from the back to the front.
Hold the thread with your right hand so that there is no slack in the
thread that is pulled out, and then pass the thread under the thread guide
cover with your left hand.
9. Thread the machine by guiding the thread along the path indicated by
the number on the machine.

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10. Pass the thread into the thread take-up lever from the right to the left.
11. Pass the thread behind the needle bar thread guide.
The thread can easily be passed behind the needle bar thread guide by holding
the thread in your left hand, then feeding the thread with your right hand, as
shown.
12.Lower the presser foot lever to lower the presser foot.

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Threading process for lower thread
1. Remove the bobbin case by pulling on the bobbin case latch.
2. Remove the bobbin from the case and wind the thread.
3. Put the bobbin back to the bobbin case and pull the thread through the little slot at
least 4 inches.
4. Be sure that you hear the bobbin case inside the shuttle.
5. Start the mechanism by rolling the balance wheel forward to get the thread of the
bobbin through the needle. 6. Pull the upper and lower thread together by 4 inches.
Conclusion
The lock stitch which is used in most modern machine is formed from a single
thread by this experiment we able to know about the part if a single needle lock
stitch sewing machine will be useful for the future.
References
1. https://gltnhs-tle.weebly.com/lesson-
41.html?fbclid=IwAR1Ak67UPlVjIbjE0IBFfA_DDlScSJuhWZ6plBL33Pi
S8Ma5XWsPr10VdgY
2. https://industrialsewingmachine.global.brother/en-ap/lock/index.aspx
3. https://apparelresources.com/technology-news/manufacturing-tech/know-
single-needle-lockstitch-machine-easing-sewing-
operations/?fbclid=IwAR1MWLLwM9MAa1D9UStXx8OCfyBK2FK-
9w3rfFXmhR5Go_ISgY9RSJyihxw