Singer 321C - User manual

High Speed
Overlock Machine
131M-04
132M-015
133M-04 / TF
134M-04
241M-24 / 25
243M-24 / TF
244M-24
251M-35
251M-55
251H-56
321C
Instruction Manual
and Parts List
® Singer is a registered trademark of The Singer Company Limited or its affiliated companies.
© 2009 Copyright The Singer Company Limited

Contents
1Safety Instructions 1
1.1 Important Safety Instructions 1
1.2 Safe Operation 2
2Product Description and Machine Specification 3
2.1 Product Description 3
2.2 Machine Specification 4
2.3 Motor, Motor Pulley and Belt 4
3Mounting and Adjustment Instructions 5
3.1 Table Cut-Out Diagram 5
3.2 Machine Installation 6
3.3 Lubrification and Oil Drainage 8
3.4 Needle Attachment (or Replacement) 9
3.5 MachineThreading 9
3.6 ThreadTension Adjustment 10
3.6.1 Tension Nut Adjustment 10
3.6.2 NeedleThread Control 10
3.6.3 LooperThread Control 11
3.6.4 Chain LooperThread Cam Control 11
3.7 Adjusting the Differential Feed Rate 12
3.8 Stitch Length Adjustment 12
3.9 Parts Relation andTiming 13
3.9.1 Needle and Needle Plate 13
3.9.2 Upper Looper (Spreader) and Needle 14
3.9.3 Lower Looper and Needle 14
3.9.4 Upper and Lower Loopers 15
3.9.5 Needle and Needle Guard 15
3.9.6 Chain Looper and Needle 15
4Maintenance 16
4.1 Machine Head Cleaning 16
4.2 Oil Change and Filter Cleaning 16
4.3 Safety Inspection 16
5Troubleshooting 17

6Parts List 19
6.1 Frame Components 20
6.2 Cloth Plate Components 22
6.3 Cover Components 24
6.4 Main Shaft Components 26
6.5 Needle Bar Components 28
6.6 Thread Guide Components 30
6.7 Upper Looper Components 32
6.8 Lower Looper Components 34
6.9 Front Looper Components 35
6.10 Cam Components 36
6.11 Differential Feed Components 38
6.12 Feed Dog Components 40
6.13 Trimming Components 42
6.14 Presser Foot Components 44
6.15 Lubrication Components 46
6.16 Feed Snap Components 48
6.17 Thread Spool Components 50
6.18 Plate Row Material Components 52
6.19 Accessories 53
7Gauge Parts List 54
Contents

1
High Speed Overlock Machine |Instructions 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in
thefollowingsituations:
•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main-
tenance.
•When the operator is not run-
ningthemachine.
•In case of lubricant oil contact
with the eyes or skin, wash the
surface with plenty of icy 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ad-
equate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.

2
High Speed Overlock Machine |Instructions Manual and Parts List
•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
fingers, head, and clothes far
fromwheel,beltandmotorwhen
the machine is running. Nothing
shouldbeplacednearthoseparts.
•To avoid injuries never put your
fingers next to the loopers when
themachineisrunning.
•The shuttle whirls at high speed
while the machine is running.To
avoid hand injuries, keep them
away from the shuttle while the
machine is running.Turn off the
machinetoreplacethebobbin.
•Toavoidpossibleinjuriesbecare-
ful when putting down or lifting
themachinehead.
•To avoid accidents in case of a
sudden start of the machine al-
ways turn it off when laying it
down, or remove the belt cover
andthebelt.
•If your machine is equipped with
a servomotor, it does not make
noiseswhilebeingdriven.Toavoid
a possible accident caused by an
unexpectedstart,bevsurethema-
chineisturnedoff.
•To avoid electric, do not run the
machinewithoutproperground-
ing.
•To minimize the risk of accidents
or damages in electric compo-
nentscausedbyelectricdischarge
turn the machine off before un-
pluggingit.
•Cleanthemachineperiodically.
1.2
Safe Operation

3
High Speed Overlock Machine |Instructions Manual and Parts List
High Speed Overlock Machine
Product Description
and Machine Specification
2.1
Product
Description

4
High Speed Overlock Machine |Instructions Manual and Parts List
2.2
2.3
Machine
Specification
Motor, Motor
Pulley and Belt
• Clutch motor 1/2 HP (400W) high
speed (2 poles)
• Belt type M
Model
321C
Needle Thread Gauge
[mm]
Stitch
width
[mm]
Stitch
Length
[mm]
Differential Presser
Height
[mm]
Needle
Singer Type
Speed
[spm]
Usage
131M-04
1 3 -
4.0
3.6 0.7~2.0 5.5
6120-06 75/11 6,000 Three-thread overlock machine
132M-015 1.5 6120-06 65/9 6,000 Three-thread handkerchief edging
(rolled hem) overlock machine
133M-04 / TF 4.0 6120-06 75/11 5,500 Three-thread elastic attaching
overlock machine
134M-04 4.0 6120-06 75/11 6,000 Three-thread back latch overlock
machine
241M-24
242
4.0
3.6 0.7~2.0 6.0
6120-06 75/11 6,000 Four-thread overlock machine
241M-25 5.0 6120-06 75/11 6,000 Four-thread overlock machine
243M-24 / TF 4.0 6120-06 75/11 5,500 Four-thread elastic attaching
overlock machine
244M-24 4.0 6120-06 75/11 6,000 Four-thread back latch overlock
machine
251M-35
35
3.0 5.0 3.6
0.7~2.0 6.0
6120-06 90/14 5,500 Five-thread overlock machine
251M-55 5.0 5.0 3.6 6120-06 90/14 5,500 Five-thread overlock machine
251H-56 5.0 6.0 5.0 6120-06 130/21 5,500 Five-thread heavy duty
overlock machine
Maximum Machine
Speed [spm]
Motor Pulley Diameter [mm]
60 Hz 50 Hz
4,500 70 90
4,750 75 95
5,000 80 100
5,250 85 105
5,500 90 110
6,000 95 115

5
High Speed Overlock Machine |Instructions Manual and Parts List
Mounting and Adjustment Instructions
3.1
Table Cut-Out
Diagram
Figure 1

6
High Speed Overlock Machine |Instructions Manual and Parts List
Machine
Installation
3.2 Installthemachinesupportcompo-
nentsandtheresiduescamasindi-
catedongure2.Incaseofsemi-in-
sertedassemblythedistance from
theneedlebedsurfacetothetable
topis100mm.Forinsertedassem-
blythedistanceisabout5.0mm.
Figure 2

7
High Speed Overlock Machine |Instructions Manual and Parts List
Machine
Installation
Set the machine head on the sup-
portbase.
Connectthemachinewheeltothe
motorwiththebelt.
Adjustthebelttensionsothatthere
isagapofabout20mmwhenthe
centerofbeltispressured.
Setthebeltcoveraccordingtog-
ure4.
Figure 3
Figure 4
Install the friction motor pedal at
therightsideandthepedalofthe
presserlifterattheleftside.
Besure the motor is clockwise di-
rected,referredtogure3.
3.2

8
High Speed Overlock Machine |Instructions Manual and Parts List
3.3
Lubrication
and Oil
Drainage
As this is a high
speed machine,
DO NOT run the
machine before
oiling and assuring
the direction of
motor rotation.
Important
Remove the oil ow sight win-
dow ‘A’ and ll with the lubricant
oil (Singer Oil), until the indicator
oftheoillevelisbetweenthetwo
linesoftheoillevel sightwindow
‘B’.Afterthat,putbacktheoilow
window‘A’andsqueezeit.
When using the machine for the
rst time, or a machine that has
not been used for some time, oil
theneedlebartop,theguidesand
loopersbeforerunningit.
A new machine should be run at
80% maximum speed on the rst
four weeks.After this initial cycle,
Figure 5
Figure 6
C
B
replace the oil and from then on
themachine can be used atmaxi-
mumspeed.
To preserve the machine, change
theoilafterfourweeksofuse.After
thattheoilmustbechangedevery
fourmonths.Tochangetheoilsim-
plyremovethescrew‘C’indicated
on gure 6. After draining the oil,
replacethescrewandcompletethe
machinewithnewoil.
This machine has an oil lter (g-
ure 6) that must be cleaned every
monthorchangedasneeded.
Oil
Oil
A

9
High Speed Overlock Machine |Instructions Manual and Parts List
3.5
Machine
Threading
Refer to the sewing
type you need for
correct threading. Any
incorrect threading
may cause thread
brake, uneven
stitches or skip
stitches.
Important
For five thread machine For three / four thread machine
3.4
Needle
Attachment
(or Replacement)
UseneedleSinger6120-06.
Release screw ‘1’ as indicated on
gure 7 and put (or withdraw the
oldneedle).
Inserttheneedlewiththeslotturned
tothebacksideandpushitupuntil
thebarend.Tightenscrew‘1’.
Figure 7
Figure 8 Figure 9

10
High Speed Overlock Machine |Instructions Manual and Parts List
3.6
Thread Tension
Adjustment
The thread tension should be adjusted according to the type and thickness of
cloth, thread, sewing width, stitch length and others. Therefore, the pressure on
theTension Buttons orThread Guides should be individually adjusted for each case.
Important
3.6.1
Tension Nut
Adjustment
The following adjustments are re-
latedtogure10.
Tension Nut 1: controlsthe needle
threadortheleftthreadincaseof
twoneedles.
Tension Nut 2: controls the thread
intherightneedle.
Tension Nut 3: controls the thread
intherightlooper
Tension Nut 4: controls the thread
intheleftlooper
Tension Nut 5: controls the thread
ofthesafetystitch.
Figure 10
3.6.2
Needle
Thread Control
Foralltypesofstitch504,512or514,
movedowntheguides‘1’ and‘2’.
Forthetypesofstitch503and505,
movethe guides‘1’ and ‘2’ tothe
highestpoint.
Figure 11
The signal (+)
increases the tension
in the thread. The
signal (-) reduces the
tension of the thread.
Note

11
High Speed Overlock Machine |Instructions Manual and Parts List
3.6.3
Looper
Thread Control
Forthetypeofstitch512,whenAd-
justguide ‘1’ and ‘2’ asfollowsthe
looperontherightisattheleftfar
end,adjust‘1’ and ‘2’inlevelwith
thedottedmark,asongure12.
Forthetypeofstitch503and505,
move the guides to the lowest
pointandadjust ‘1’ and ‘2’ inlevel
withthecontinuousline.
Adjust guide ‘3’ as follows:
•Position‘A’:forstretchythread
•Position‘B’:forseamingandblind
stitchhemming
•Position‘C’:stitchtype512
Adjust guide ‘4’ as follows:
•Position‘D’:forstretchythread
•Position‘E’:forseamingandblind
stitchhemming.
Figure 12
3.6.4
Chain Looper
Thread Cam
Control
When the needle is on high posi-
tion,mark ‘A’ mustbealignedwith
the thread guide bracket ‘1’, as
shownongure13.
Release screw ‘2’ and the thread
cam‘3’. Turnitclockwiseforquick
releaseofthreadthroughthecam.
Figure 13
The signal (+) means
more thread and (-)
means less thread.
Note

12
High Speed Overlock Machine |Instructions Manual and Parts List
3.7
Adjusting the
Differential
Feed Rate
Adjustmentofthedifferentialisthe
dragging proportion between the
mainfeeddoganddifferencialfeed
dog.Whenthemovementofmain
feed dog is less than that of the
differencialfeeddog,theclothwill
befrilledduringsewing.Otherwise,
theclothwillbestretched.
3.8
Stitch Length
Adjustment
The stitch length
adjustment is
made according to
the sewing fabric,
differential feed ratio
and other factors.
Important
Pressbuttontotheendandkeepit
pressedasshownongure15.
Turn the wheel until we have the
desiredstitchlength.Itisshownon
thewheelscale.
Figure 15
Figure 14
Releasenut‘1’ ongure14,andturn
screw‘2’ clockwisetostrechingthe
clothorcounterclockwisetoshrink
it.Retightendthenut‘1’.
Adjust
Differential
Scala
12345
1 : 3 - 1 : 0.7 1 : 0.9 1 : 1.1 1 : 1.3
1 : 2 1 : 0.7 1 : 1.0 1 : 1.4 1 : 1.7 1 : 2.0
1 : 3 1 : 1.0 1 : 1.5 1 : 2.0 1 : 2.5 1 : 3.0
1 : 4 1 : 1.1 1 : 1.6 1 : 2.3 1 : 2.8 1 : 3.3
When the surface of
level ‘3’ adjustment
is on scale 2, the
differential adjustment
is 1 : 1, and if it is
on the scale, its
proportion may be
adjusted up to 1 : 0.7.
Note
Dragging
Proportion
Type of
Machine
Wheel Scale
1234567
1 : 2.0 Seaming 1.0 1.5 2.0 2.5 3.0 3.5 3.8
1 : 3.0 Shirring 0.7 1.0 1.4 1.7 2.0 2.3 2.5
1 : 1.3 Serging 1.6 2.3 3.1 3.9 4.7 5.4 5.9
1 : 4.0 Special 0.6 0.9 1.2 1.5 1.8 2.1 1.0

13
High Speed Overlock Machine |Instructions Manual and Parts List
3.9
Parts Relation
and Timing
3.9.1
Needle and
Needle Plate
When needle at the highest posi-
tion, distance ‘A’ between needle
point (the left needle if there are
two needles) and needle plate is
9.5to9.7mmforstandardadjust-
ment, or 10.8 to 11.0 mm for spe-
ciccases. Each needleshould be
centralized over each hole in the
needleplate.Therightneedlemust
beabout0.2to0.3mmaheadthe
leftneedle.
Distancebetweenneedlepoint(the
right needle if there are two nee-
dles)andthefrontpartofthehole
intheneedleplateorpresserfoot
is1.2mm.
Releasescrew‘1’,asshownong-
ure16.
Turn the wheel to see if needle is
centralized at every hole of the
needle plate. Release screw ‘2’ to
adjustneedleholder.
Turn the wheelto moveneedle to
thehighestpositionandmovenee-
dlebaruntiltheheightiscorrectly
adjusted.
Tightenscrews‘1’ and‘2’.
Figure 16

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High Speed Overlock Machine |Instructions Manual and Parts List
Figure 18
Figure 19
3.9.2
Upper Looper
(Spreader)
and Needle
Whentherightloopermovestothe
farleftend,distance‘A’ betweenthe
looper point and the center line of
theneedleis4.5to5.0mmforone
needle. For two needles, the dis-
tance‘B’ is5.5to6.0mmfromthe
leftneedle,asshownongure17.
3.9.3
Lower Looper
and Needle
When the lower looper moves to
the extremly left, the distance ‘A’
between looper point and center
line of the needle (left needle, if
twoneedles)isfrom3.4to3.6mm,
forhighliftmachines,asshownon
gure18.
When the lower looper moves to
the center line of needle (left nee-
dle, if two needles), the gap be-
tweenneedleandlooperisfrom0
to0.05mm,asshownongure19.
Figure 17

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High Speed Overlock Machine |Instructions Manual and Parts List
3.9.4
Upper and
Lower Loopers
Whentheupperandlowerloopers
arecrossed,thedistanceis0.2mm
for‘A’ and0.5mmfor‘B’, accord-
inggure20.
Figure 20
3.9.5
Needle and
Needle Guard
When the looper point is on the
side opposite to the center line of
theneedle (left needleif thereare
two needles), space between nee-
dleandrear needleguardof ‘A’ is
0mm.When needlemovesto the
lowest position, space between
needle and front needle guard of
‘B’ isfrom0.15to0.20mm,accord-
ingtogure21.
Figure 21
3.9.6
Chain Looper
and Needle
Thesafetyloopershouldbexedin
apositionlowerthanthissupport.
And when it moves to the left far
end,thedistancebetweentheloop-
erpointandthecenterlineofneedle
is2.5mm,accordingtogure22.
Figure 22

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High Speed Overlock Machine |Instructions Manual and Parts List
Maintenance
4.1
Machine
Head Cleaning
Clean the machine head periodi-
callywithadrysoftclothtoremove
theexcessofdustinthehead. Do
notuseanykindofsolventmaterial
tocleanthesurface.
4.2
Oil Change and
Filter Cleaning
Ifthemachinehasnotbeenusedfor
a long time, lubricate the superior
part of the needle bar, guides and
loopers before returning to opera-
tion.
Oil should be changed every four
months.Whenchangingtheoilfol-
lowinstructionsonitem3.3.
Oil lter should be cleaned every
month or replaced for a new one
as necessary.To clean the lter or
changetheoil,followinstructionin
item3.3.
4.3
Safety
Inspection
Frequently check if all safety de-
vices are properly installed and
adjusted.
Checkallscrewsthatxandhold
the machine head that should be
properlytight.
Checkand be sure thebelt isnot
excessivelywornoutandseethat
ithasthepropertension.
Checkandbesurethereisnomo-
tor overheating and be sure that
the cable and electric connector
arenotdamaged.