Singer 20U-105C User manual

Zigzag Sewing Machine
Instruction Maqnual
and Parts List
SINGER and the Cameo "S" Design are exclusive trademarks of The Singer Company Limited S.à r.l. or its Af liates.
©2017 The Singer Company Limited S.à r.l. or its Afliates. All rights reserved.
20U105 / 105C
125 / 125C

Contents
1 Safety Instructions 1
1.1 Important Safety Instructions 1
1.2 For Safe Operation 2
2 Product Description and Machine Specification 3
2.1 Product Description 3
2.2 Machine Specification 4
2.3 Motor, Motor Pulley and V-Belt Specifications 4
2.4 Relationship between Zigzag Bight and Maximum Speed 4
5snoitcurtsnItnemtsujdAdnaputeS3
3.1 Table Cut-Out Drawing 5
3.2 6
3.3
Oil Reservoir Installation
7
3.4
Belt Cover Installation
8
3.5 9
3.6 9
3.7
Lubrication
10
3.8
Needle and Thread
11
3.9
Inserting the Needle
12
3.10
Bobbin Case Attachment
14
3.11
Bobbin Thread Winding
3.12
Bobbin Case Threading and Replacement
15
15
3.13
Machine Threading
16
3.14
Stitch Length Adjustment
16
3.15
Presser Foot Pressure Adjustment
17
3.16
Needle Thread Tension Adjustment
17
3.17
Thread Take-up Spring Adjustment
18
3.18
Bobbin Thread Tension Adjustment
18
3.19
Needle Position Selector
19
3.20
Stitch Width Regulator
20
3.21
Zigzag Stitch Width Control
21
3.22
Needle Bar Frame Clamp Device
22
3.23
Straight and Zigzag Stitch Fitting
22
3.24
Spool Cap Usage
25
3.25
Thread Anti-Spill Net Usage
25
3.26
Knee Lifter Installation
26
Fittings for Buttonhole Stitching
Fittings for Hem Sewing
Fittings for Zipper and Cord Sewing

Contents
4
5
6
Maintenance 27
4.1Machine Head Cleaning 27
4.2
4.3
Lubrication 27
Safety Inspection 27
Troubleshooting 28
Parts List 29
6.1
6.2
Face Plate, Arm Top Cover and Arm Side Cover Components 30
Thread Take-up, Arm Shaft and HandwheelComponents 32
6.3
Needle Bar, Presser Bar and Needle Plate Components 34
6.4 Zigzag Triangular Cam and Hook Advancing Crank Components 36
6.5 Bight Amplitude and Bight L-C-R Position Components
6.6 Arm Shaft (upright) and Rotating Hook Drive Shaft Components 40
6.7 Hook and Bobbin Case Components 42
6.8 Feed RegulatingDial and FeedReverse Lever Components 44
6.9 Feed Mechanism Components 46
Presser Bar Lifter and Thread Tension Components 48
Thread Stand Components 50
6.12 Accessories and Attachments 52
6.13
6.10
6.11
Belt Cover Components 54
38

1
Zigzag Sewing Machine |Instruction Manual and Parts List
Safety Instructions
1.1
Important Safety
Instructions
Important
• Before running the machine, make
sure all relevant safety specifica-
tions are adequate to specifica-
tions and technical standards in
your country.
• The machine should not be run
without its safety devices.
• The machine should only be oper-
ated by properly trained personnel.
• For your safety, goggles must be
used while running the machine.
• Turn off or unplug the machine
when the following situations arise:
• Passing the thread by the nee-
dle or replacing the bobbin or
looper.
• Replacing the needle, presser
foot, throat plate, feed dog and
sliding plate.
• When the machine is in mainte-
nance.
• When the operator is not run-
ning the machine.
• In case of lubricant oil contact
with the eyes or skin, washed the
surface with plenty of icy water
with a generous amount of cold
water. In case of ingestion, seek
medical help immediately.
• Repair, fitting or maintenance
should only be performed by
properly trained personnel.
• Maintenance and repair on elec-
tric equipment should only be
made by qualified personnel. If
any electric device is damaged,
the machine should be immedi-
ately stopped.
• Before starting the machine in full
running, a test must be conducted
to assure that machine and opera-
tor are able to perform the task.
• The machine should not be placed
next to a sound source as an ultra-
sonic welding machine and other
equipment.
• The machine should only be run
with the proper electric cable and
connectors, and also the adequate
grounding.
• The machine should only be used
to sew materials as indicated in
its instructions manual, and indi-
cations of use should be followed.
Singer will not be held responsible
for any damage caused by unau-
thorized changes in the product.
When using the
machine, basic safety
procedures must
be followed. Read
with attention all
instructions before
using the machine.
When using it,
understand that
all basic safety
instructions are
not limited to the
following items.
Read all instructions,
take care of this
manual, and use it
as reference when
necessary.

• To avoid the risk of electric shock,
do not open the motor wiring box
and do not touch the components
assembled inside the wiring box.
• To avoid injuries do not run the
machine without the belt cover or
in case any other safety device is
removed.
• To avoid possible injuries keep fin-
gers, head and clothes far from
wheel, belt and motor when the ma-
chine is running. Nothing should be
placed near those parts.
• To avoid injuries never put your
fingers next to the rotating hook
and the thread take-up lever cover
when the machine is running.
• To avoid possible injuries be care-
ful when putting down or lifting
the machine head.
• To avoid accident in case of a sud-
den start of the machine always
turn it off when laying it down, or
remove the belt cover and the belt.
• If you machine is equipped with
a servomotor, it does not make
noises while being driven.To avoid
a possible accident caused by an
unexpected start, be sure the ma-
chine is turned off.
• To avoid electrical shock, do not
run the machine without proper
grounding.
• To minimize the risk of accidents
or damage in electric components
caused by electric discharge turn
the machine off before unplug-
ging it.
• Clean the machine periodically.
1.2
For Safe
Operation
2
Zigzag Sewing Machine |Instruction Manual and Parts List

Zigzag Sewing Machine 20U series
Product Description
and Machine Specification
2.1
Product
Description
3
Zigzag Sewing Machine |Instruction Manual and Parts List

4
2.2
Machine
Specification
Table 1 – Machine Specification
20U-105/ 105C
For sewing
Stitch type
Max. speed[1] 2,500 rpm
Max. stitch bight 9.0 mm
Max. stitch length
Needle bar stroke
Presser bar lift (manual)
Presser bar lift (knee lifter)
Needle catalog (needle system)
Oil
Cat. 1910-05 (135x9)
Singer Oil
3.0 mm
34.8 mm
6.35 mm
9.0 mm
Singer model
Light to medium
Plain zigzag (Straight stitch)
20U-125 / 125C
2,000 rpm
12.0 m
Maximum speed will vary depending on fabric, threads and sewing condition
2.3
Motor,
Motor Pulley
and V-Belt
Specifications
1/3 HP (250W) 4-pole (low speed) clutch motor
M type v-belt
Table 2 – Machine Speed vs. Motor Pulley Diameter
2,500 - 130 105
2,000 2,000 105 85
1,800 1,80090 75
1,500 1,50080 65
Motor Pulley Diameter
[mm]
Machine Speed
[spm]
2.4
Relationship
between
Zigzag Bight
and Maximum
Speed
Table 3 - Relationship between Zigzag Bight and Maximum Speed.
Machine Class
Zigzag bight
Max. speed2,500 rpm
20U-105 / 105C20U-125 / 125C
20U-105 /105C 20U-125/ 125C
50 Hz 60 Hz
1,800 rpm
2,000 rpm
2,000 rpm
5.0 ~ 12.0 mm
5.0 ~ 9.0 mm
0 ~ 5.0 mm 0 ~ 5.0 mm
Zigzag Sewing Machine |Instruction Manual and Parts List

5
Setup and Adjustment Instructions
3.1
Table Cut-Out
Drawing
Figure 1
Zigzag Sewing Machine |Instruction Manual and Parts List

6
3.2
Oil Reservoir
Installation
Figure 4
Figure 3
Figure 2
The oil reservoir should be fixed on the side of the machine table groove
by using four nails (Figure 2).
Two rubber seats and two rubber
corners for supporting the head
portion should be fixed on the
extended portion of the table by
25mm
using nails, and the other two
rubber cushion on the hinge side
should be fixed on grooves by
using nails too (Figure 3).
Two hinges ‘1’ fit into the hole in the
machine bed, and the machine head
fitted the table hinge’s rubber ‘2’ ,
before the machine head is placed to
the cushions on the four corners of
the table (Figures 3 and 4).
1
12
Zigzag Sewing Machine |Instruction Manual and Parts List

7
3.3
Belt Cover
Installation
Figure 5
The machine belt cover
Install the machine belt cover so
that the hand wheel and v-belt
move freely without interference,
and then tighten the screw at this
position (see Figure 5).
The motor belt cover
Install the motor belt cover so that
motor pulley and v-belt will rotate
freely without interference.
Caution
Switch off the
machine.
Set sewing head
upright again
using both hands.
Danger of crush-
ing between
sewing head and
table top.
For your safety,
do not run the
machine without
the belt cover.
Zigzag Sewing Machine|Instruction Manual and Parts List

8
3.4
Lubrication
Figure 7
Figure 6
The rotating hook, and the area at
the under of the needle plate.
Turn handwheel over toward you
until oil hole in the rotating hook
appear in sight.
Regularly apply one or two drops of
oil to the oil hole at the rotating
hook (Oiling point at the Figure 6).
Remove the face plate and the top
cover.
Apply sufficient oil to all oil felt and
indicate with oiling points shown in
Figure 7
Apply a small amount of grease to
gear teeth indicated at the 'B'.
Keep the oil saturated with the oil
reservoir felt ‘A’ at the under of the
top cover.
Caution
Switch off the
machine.
Set sewing head
upright again
using both hands.
Danger of crush-
ing between
sewing head and
table top.
For your safety,
do not run the
machine without
the belt cover.
Important
When you first
operate your
machine after set
up or after an
extended period
of disuse, oil the
machine and run
your machine at
1,000 to 1,500
spm for about 10
minutes for the
purpose of
bread-in.
A
B
BB
Zigzag Sewing Machine |Instruction Manual and Parts List

9
3.5
Needle and
Thread
Figure 8
Selection of the proper needle
depends not only on the machine
model, but also on the material and
thread used. For selection of proper
needle and thread sizes to be used
on the various machine models
please refer to the table below.
Caution
The power
supply should
be cut off
before attach-
ing the needle.
3.6
Inserting
the Needle
Use needle Cat. No. 1910-05 needle
system (135x9) only.
Raise needle bar to its highest
position by turning handwheel
toward you.
Loosen needle set screw ‘1’ (see
Figure 8). Insert the needle in the
needle bar and push it up as far as it
will go.
Make sure its long groove faces
toward the front.Tighten needle set
screw ‘1’ securely.
Caution
Switch off the
machine.
Do not operate
the machine
without the
finger guard ‘2’
(see Figure 8)
1
2
* or an equivalent size of other types of thread
Table 4 - Needle andThread
Model
Application Light weight
materials
Medium weight
materials
Mid-heavy weight
materials
Max. thread size (Nm)-
Synthetic* 120 60 30
Needle size (1/100mm) 10 (60) 12 ~ 16 (80 ~ 100) 18 ~ 19 (110 ~ 120)
Needle catalog
(Needle system)
20U-105 / 105C / 125 / 125C
1910-05(135x9)
Zigzag Sewing Machine |Instruction Manual and Parts List

10
3.7
Bobbin Case
Attachment
Figure 9
Follow as shown in Figure 9
1. Open bed slide.
2. Raise latch ‘1’.
3. Lift out bobbin case ‘2’.
Caution
Switch off the
machine.
Do not operate
the machine
with throat
plate left open.
1
2
Zigzag Sewing Machine |Instruction Manual and Parts List

11
3.8
Bobbin
Thread
Winding
Threading the pre-tension for bobbin winding
Figure 10
Place bobbin on bobbin winder
spindle ‘3’ and pushing it on as far
as it will go.
‘1’ adjustment.
‘+’ direction: Increase tension
‘-‘ direction: Decrease tension
Push latch ‘2’ in the direction indi-
cated by arrow ‘A’, then start the
machine.
Bobbin winder spindle ‘3’ is rotate
in the direction indicated by arrow
‘B’.
To adjust the amount of thread on
bobbin, loosen screw ‘4’ on latch ‘2’
and swing the latch ‘2’ away from
you or toward you, as required.
For more thread on bobbin,
swing latch ‘2’ away from you.
For less thread on bobbin,
swing latch ‘2’ toward you.
If thread winds unevenly on bobbin,
loosen screw ‘5’ and move pre-
tension ‘1’ up or down, as required,
and tighten screw ‘5’.
2
A
B
1
5
4
3
Caution
Do not guide or
hold thread
when winding
the bobbin.
Zigzag Sewing Machine |Instruction Manual and Parts List

12
3.9
Bobbin Case
Threading and
Replacement
Figure 12
Figure 13Figure 14
Figure 11
Hold bobbin case so that bobbin
rotates in the direction of the arrow,
and put bobbin in the bobbin case.
(Figure 12)
Put thread into notch ’1’, and pull it
under tension spring ‘2’ (Figure 13)
Pull thread out from slot ‘2’ on end
of spring ‘1’, and pass it through
bobbin case thread guide ‘3’.
Leave thread approximately 4
inches longer from in the bobbin
case. (Figure 14 and 15)
2
2
3
1
1
Note
When straight
stitching, a
better result
can be obtained
if bobbin thread
is not threaded
through bobbin
case thread
guide ‘3’ of
Figure 15.
Zigzag Sewing Machine |Instruction Manual and Parts List

13
Figure 15
Hold bobbin case by latch ‘1’ and
place it on spindle of bobbin case
holder ‘2’ so that position finger ‘3’
enters notch ‘4’ at right of bobbin
case holder (see Figure 12).
Release latch and press bobbin case
firmly in place to assure proper
position. Close bed slide.
Caution
Switch off the
machine.
Do not run
machine with-
out closing bed
side. Danger of
injury!
1
3
4
2
Zigzag Sewing Machine |Instruction Manual and Parts List

14
3.10
Machine
Threading
Figure 16
When threading the machine head,
the needle bar should be at the
highest point of its stroke.
Caution
Switch off the
machine.
Do not operate
the machine
without thread
take-up guard.
Do not operate
the machine
without finger
guard.
Threading the machine in the order
shown in the Figure 19.
Leave thread approximately 4 cm
longer in the needle.
1
2
3
4
7
8
5
6
Zigzag Sewing Machine |Instruction Manual and Parts List

15
3.11
Stitch Length
Adjustment
Figure 17
Adjusting the stitch length:
Turn stitch length dial ‘1’ in the
direction of the arrow, and align the
desire number to marker dot ‘A’ on
the machine (Figure 20).
The indication of the stitch length
dial ‘1’ is in millimeters.
Adjusting the reverse stitch length:
Push feed reverse lever ‘2’ down for
reverse feed, and release it for
forward feed.
To adjust the reverse stitch length
turn thumb screw '3' in direction of
the marker ‘+’or‘-' as requested for
the stitch length.
‘+’ direction:To lengthen
‘-‘ direction:To shorten
3.12
Presser Foot
Pressure
Adjustment
Figure 18
Loosen the nut ‘2’ and turn the
presser spring regulator ‘1’ clock-
wise (in direction of the marker ‘+’),
the pressure of the presser foot will
be increased.
Turn the regulator ‘1’ counter clock-
wise (in direction of the marker ‘-‘ ),
the pressure of the presser foot will
be decreased.
Tighten the nut ‘2’.
1
2
2
A
13
Zigzag Sewing Machine |Instruction Manual and Parts List

16
3.13
Needle
Thread
Tension
Adjustment
Figure 19
Adjusting the tension of needle
thread using tension adjusting nut
‘1’ according to different sewing
condition. (Figure 20)
Turn the nut ‘1’ clockwise (in direc-
tion of the marker ‘+’), the tension
will increase.
Turn the nut ‘1’ counterclockwise (in
direction of the market ‘-‘), the
tension will decrease.
3.14
Thread
Take-up
Spring
Adjustment
Figure 20
The adjusting of the pressure of the
thread take-up spring ‘4’ (Figure
21).
Turn the thread tension post ‘1’
clockwise (in direction of the marker
‘+’), the pressure will be increased.
Turn the thread tension post ‘1’
counterclockwise (in direction of
the marker ‘-’), the pressure will be
decreased.
The adjusting of the stroke of the
thread take-up spring ‘4’. (Figure 21)
Loosen setting screw ‘2’.
Turn the thread tension ‘3’ clock-
wise (in direction of the marker ‘+’),
the stroke of the thread take-up
spring will be increased.
Turn the thread tension ‘3’ counter-
clockwise (in direction of the marker
‘-’), the stroke of the thread take-up
spring will be decreased.
1
1
2
3
4
Zigzag Sewing Machine |Instruction Manual and Parts List

17
3.15
Bobbin
Thread
Tension
Adjustment
Figure 21
Turn the tension adjusting screw ‘1’
clockwise (in direction of the marker
‘+’), the bobbin thread tension will
increase.
Turn the tension adjusting screw ‘1’
counterclockwise (in direction of
the marker ‘-’), the bobbin thread
tension will decrease.
3.16
Needle
Position
Selector
Figure 22
Left, Center and Right needle posi-
tion settings are available for place-
ment of both straight and zigzag
stitching (see Figure25).
To position, push lever in and move
to desired setting.
Center setting:
Normal sewing.
Left/Right setting:
Only used when special place-
ment of stitching is desired.
Caution
Do not make any
needle position
adjustment while
the needle is in
the fabric.
Switch off the
machine.
1
Zigzag Sewing Machine |Instruction Manual and Parts List