Singer Safety 491D Manual

Singer 491D Sewing Machine
Operator's Guidebook
SINGER
INDUSTRIAL PRODUCTS

CONTENTS
Page
Introducing the new Singer model 491D machine 1
Machine Lubrication 2
Needles 3
Thread 3
Needle Setting 4
Threading the Machine 4
Removing the Bobbin 5
Winding the Bobbin 6
Threading of Bobbin Case 7
Replacement of Bobbin Case 7
Preparation for Sewing 8
Sewing 8
Needle Thread Tension Adjustment 9
Thread Tension Spring Adjustment 10
Thread Protector Adjustment 10
Presser Foot Pressure Adjustment 11
Stitch Length Adjustment 11
Tips for Perfect Operation 12
V.
Copyright (C) 1973 THE SINGER COMPANY
All rights reserved worldwide.
J

INTRODUCING THE NEW SINGER
MODEL 491D SEWING MACHINE!
This is the most reliable and lightest
running machine in its class. This fixed
needle machine produces a high
quality straight seam for both fine
fabrics such as lingerie and thick fabrics
such as denim jeans and those used for
overcoats and jackets.
The machine can reach speeds of up to
5,500 revolutions per minute.
With an oil tank, a pump and a minimum
of wicks, all parts that need oil are
constantly lubricated. Oil flow can be
easily checked by a sight glass located
on the arm top cover.
Quiet and smooth in operation, the
Model 491D machine is designed for
your comfort — making sewing
smoother, faster and more profitable.
1

LUBRICATING THE MACHINE
Oil your machine! For best results, Type "C" is mostly used when it is
always use SINGER* type "A" or type desired to minimize oil stains on the
"C" oil. fabric even after long machine storage.
Tip the machine backwards and fill the
oil tank as shown in fig. 2. When the
machine is new or has been idle for
long periods, it is advisable to remove
MUST SHOW STEADY OIL FLOW
/
the face plate and oil the needle bar and
the thread tensioner bearing.
PRECAUTIONS
Correct lubrication is idicated by a
continuous flow of oil through the sight
glass when the machine is running, as
shown in fig. 3.
If oil flow becomes uneven, STOP
machine and check the oil level in the
tank. Fill up as necessary.
At least twice a month, check the level
in the tank. Never allow the oil level to
drop below the "low add oil" mark
shown in fig. 2.
Fig. 3 Oil Flow Window

NEEDLES
The needles you use directly affect the
quality, strength and appearance of the
stitching produced by your machine.
That is why the use of SI NGER needles
is so important, according to the table
below:
NEEDLES
CATALOG No.
CLASS AND
VARIETY
SIZES
1901 135x7
8, 9, 10, 11, 12, 13, 14, 15, 16, 17,
18, 19, 20,21,22, 23 & 24
1955
A bent needle will cause stitch failures A needle with a damaged or burred tip
and sewing irregularity. results in poor work finish and may
damage the fabric.
THREAD
In the Class 491D, ONLY use left twist
thread in the needle. Either right or left
twist thread can be used in the bobbin.
To determine the thread twist, hold the
thread as shown below.
Then roll the thread over toward you
with your right hand. If the strands of the
thread wind tighter, the thread is left
twist; if the strands unwind or separate,
the thread is right twist.
HOLD THIS END.
Fig. 4 Determining Thread Twist

TO SET THE NEEDLE
MOVE TO
HIGHEST POINT.
LOOSEN SCREW.
( I N S E R T NEEDLE UP
AS FAR AS POSSIBLE.
LONG GROOVE.
Setting the Needle Fig. 5
Rotate the machine pulley over toward
you until the needle bar moves to its
highest point.
After loosening the needle set screw,
insert the needle up to the top as shown
in fig. 5.
The long groove of the needle should
face the left end of the machine, as
shown in fig. 5.
Then firmly tighten the needle set
screw.
Threading the Needle
Upper Threading
THREADING THE MACHINE
First rotate the machine pulley over
toward you until the needle reaches its
highest point, then pass the needle
thread from the unwinder through the
threading points in the order shown in
fig. 6. Pull about two inches of thread
through the eye of the needle.
Fig. 6

REMOVAL OF THE BOBBIN
Turn the machine pulley over toward
you until the thread take-up lever is at
its highest point.
Open the slide plate. Reach under the
machine base with your left hand and
remove the bobbin case as shown in
fig. 7.
Releasing the latch will free the bobbin
as shown in Fig. 8.

WINDING THE BOBBIN.
Place the bobbin on the shaft C of the
bobbin winder by pushing it on as far as
it will go and pass the thread through
the threading points as shown in fig. 9.
Wind end of thread around the bobbin a
few times.
Press down on the thumb latch,
pushing driving pulley over against belt.
Start the machine.
The bobbin winder stops automatically.
For more thread on the bobbin, turn
screw A clockwise; for less thread,
rotate it counterclockwise.
When winding a bobbin with fine
thread, light tension should be used.
Adjust knurled screw D, fig. 9, to
regulate the tension.
If the thread winds unevenly on the
bobbin, loosen screw B and move the
tension lever left or right as necessary.
Tighten screw B.
Bobbins can be wound while sewing at
the same time.
Lubricate the thread filler periodically.
Put a few drops of oil on the filler
lubrication point shown in fig. 9.

THREADING THE BOBBIN CASE
Hold the bobbin so that the thread will
unwind in the direction shown in fig. 10.
Hold the bobbin case as shown in fig.
10, and place the bobbin inside as
shown in fig. 11.
BOBBIN CASE REPLACEMENT
After winding, hold the bobbin case by
the latch with your left hand and place it
on the center stud of the bobbin case
holder as shown in fig. 12. Release the
latch. Press the bobbin case back until
the latch catches the groove near the
stud. Leave about two inches of thread
to hang free.
Fig. 11
REPLACE BOBBIN

PREPARATION FOR SEWING
Hold the end of the needle thread
lightly. Then rotate the machine pulley
toward you until the needle moves
down and up. Then pull the needle
thread; and the bobbin thread exits
through the needle plate bore as shown
in fig. 13. Place both threads under the
presserfoot before starting sewing.
SEWING
Place the material under the presser
foot and lower it. Everything is now
ready for sewing - quickly, smoothly
and easily.
For easier material removal, stop the
machine when the needle bar begins its
downward stroke. Lift the presser foot,
draw the work back behind the presser
foot and cut the threads close to the
fabric.

NEEDLE THREAD TENSION
ADJUSTMENT
Normally, the tension of the needle and
bobbin threads should be balanced so
that if you were to look at a cross
section of a line of stitching, the needle
and bobbin threads would be locked in
the center of the thickness of the
material as shown in fig 14A. Incorrect
adjustments cause the conditions
shown in 14B and 14C.
Adjust the needle thread tension as
shown in fig 15. Make sure the presser
foot is down when making tension
adjustments.
The needle thread tension should be
just enough to form the correct stitch on
the material. See fig 14A.
For general sewing, the bobbin thread
tension should be very light. If
adjustment of the bobbin thread is
necessary, remove the bobbin case
and adjust as shown in fig 16.
PERFECT STITCHING
NEEDLE THREAD TENSION TOO TIGHT.
NEEDLE THREAD TENSION TOO LOOSE.
Fig. 14
MORE LESS
TENSION TENSION
Regulating Needle Thread Tension Fig. 15
LESS TENSION.
Regulating Bobbin Thread Tension Fig. 16

THREAD PROTECTOR
ADJUSTMENT
To achieve perfectly interlaced stitches,
taking into account material thickness
and stitch length, adjustments to the
thread protector D may be required,
which can be adjusted by moving left or
right as illustrated in fig. 18.
THREAD TENSION SPRING
ADJUSTMENT
The tension and stroke of spring
movement of the thread tensioner A
may require different adjustments
depending on the thread thickness and
the material used. Thicker threads and
thicker materials require higher
tension, while delicate materials
require lower tension. Also the
movement of the tensioner spring must
be increased to ensure correct thread
control.
Using a screwdriver on screw B, turn it
counterclockwise to decrease tension
or counterclockwise to increase
tension as shown in fig. 17.
To adjust the height of the tensioner
spring, loosen screw C (fig. 18) and turn
the entire tensioner assembly to the left
if you wish to lower it and shorten it, or
to the right to raise it and increase it.
Firmly tighten screw C.
For thick materials or long stitches,
move the thread protector to the right.
For thin materials or short stitches,
move the thread protector to the left.

TO REGULATE PRESSER FOOT
PRESSURE
Correct presser foot pressure helps
feed the work properly.
The pressure on the material should be
as light as possible, while still sufficient
to ensure properfeeding.
Adjust the presser foot as shown in fig.
19 and then firmly tighten the nut.
ADJUSTING THE STITCH
LENGTH
The stitch length adjustment scale A
controls the number of stitches per
inch. The numbers that appear on the
scale mean the number of stitches per
inch. To adjust the stitch length, rotate
scale Aas shown in fig. 20.
The machine produces a maximum of 6
stitches per inch (4 mm in length).
To change the feed direction for back
tacking, depress feed reverse lever B
quickly to its lowest position and hold it
until the back tack is complete.
11

TIPS FOR PERFECT OPERATION
• Always keep the oil level in the oil
reservoir at the "HIGH" mark.
• When turning the machine pulley,
always turn it over towards you.
• Always keep the bed slide plate
closed when the machine is in
operation.
• Clean out any lint or other waste
around the hook and between the
feed rows on the underside of the
throat plate.
• Do not try to 'help' the machine by
pulling the fabric.
• Never press the knee lifter while the
machine is running.
• Do not run the machine when
threaded unless there is material
under the presserfoot.

THE SAME!
BUY PARTS AND
NEEDLES MADE
BY SINGER.
TO BE DOUBLY SURE ...
of new machine performance, make sure that all
replacement parts and needles are exactly the
same as those in new SINGER machines.
A
LOOK FOR THE TRADEMARK
1. on every package or container.
2. on the needle or numbered part.
Needles in packaging marked "For Sinqer Machines" are
NOT made by SINGER.
TO ALL WHOM IT MAY CONCERN:
The improper placing of the "SINGER" trademark, or any
other trademark of The Singer Company (all of which are
duly registered trademarks) on any machine that has
been repaired, rebuilt, refurbished, or altered in anyway,
outside a SINGER factory or an authorized SINGER
agency is prohibited.
v
A registered trademark of THE SINGER COMPANY.
J

Translated from Portuguese edition
Available on www.archive.org