Brother EF4-B956C User manual

INSTRUCTION MANUAL
FOR
BROTHER MODEL EF4-B956C
Ultra High Speed Overlock Sew ing Machine
BROTHER INDUSTRIES, LTD.
NAGOYA , JAPAN
From the library of: Superior Sewing Machine & Supply LLC

CONTENTS
1. Specifications ....................................................................................................... ·················· 1
2. Features ............................................................................................................................... .................. 2
3. Operation ........................... .
.. ········ .................... ············ ··············. "" .................. ·····........... ~
A) Se\\'in,L( speL'd ............. . . ........... 2
B) Motor, motor pulley and helt .......................................................................................................... '>
Ci Setting
U))
..
..... .. ...... ,,
D) Oiling. drnining and maintt•mmr:e....................................................................................
..
..... .. ...... ,,
E) Necdk• r:oolt•r dt'l"iLt' ....................................................................................................................... -1
F) ~lachi•w "P"·ating di•·cction ......... . .............................................................................................. :J
G) In~talling needlt• ................................................................................................................................ ;1
II) Thn•ading .............................................................................................................................
r;
I l Stitr:he~ ......................................................................................................................................
r;
.1)
ThrL'<td ten~i4>n .............................................. ............ 7
\. Adju~tnll'nl of thrL•ad take-up.................... ........................................................................ 7
'1 Adju~ting- thr<.'ad takl'·ltp and thre;td guide ..... ............................................... 7
:t Adju~ting- thrl'ad tl'nsion screw ....................... .. ..................................... 7
KJ Adjustnwnt on pre~~un· of presser foot: Installing and remo\"ing ft•ed dogs: and Height of feed dogs H
r-..
L) Adjusting ~!itch width................................................................................................................ H
·.
'
?\I) Adjusting stitch lt•ngth ........................................................................................................................ 9
?-;) Adju,Ling diffcrc.,tial feed .................................................................................................................. 9
4. Adjustment................................................... ..............................................,....................................... 10
Al llt•ight of lll'l'dlt• ................................................................................................................................. lf)
Bl Relation hl't\l'l'L'll llt't•dk• and llll<kr loopt•r ........................................................................................ Hl
Cl ln~talling nt•edil' guard rear........................ ............................................................................. 10
Dl ln~talling lll'l'dk guard front........................ ........................................................................... II
El Relation of needk• with under and on·r l11opt•r ................................................................................. 11
Fl ln~talling and nwinlt•mtncl' of lmin•s................................................................................................. 11
1
5. Trouble shooting............................................................. ....................................................................... 1~
Al Thn•ad break......,.............................................................................................................................. 1~
B) Skip ~!itching.......................................... ................................................................................. 1:!
C) :\"ecdlc brt•a\;; .................................................................................................................................... 12
D) ftnperfect chaining-off...................................................................................................................... 1:1
El Improper thn•ad tension................................................................................................................... 13
Fl l'ttor trinllning perfonnance............................................................................................................. 13
(;) Irregular ~\itches .............................................................................................................................. 1:1
Ill Em•"ice nT;ukb along >titchc~ ........ ............................. ......................................... .. ............. J.J
I) 1\"l'L'<llt• produces too large holes....................................................................................................... U ~
6. Parts list ..............................................................................................................................................Fi
From the library of: Superior Sewing Machine & Supply LLC

1. Specifica ti ons
Name
Dimensions
Type
Stitch from
Sewing speed
Stitch length
Stitch width
Height of presser foot
Main bearings and rods
Oil
Needle bar stro ke
Needle
Feed
regulator
D ifferential feed regulator
Knives
Installation
Ultra 11 igh Speed Overlock Sew in~ :V fachi nt•
355mm X 240mm X 270mm
Oust-proof,
totally enclosed type
El3, El 3A. El2A
6. 500 ~ !it c h es per minute
lmm - :l6 mm ( for sub-class ·0 1 & - 09)
1mm- 5mm (for sub-class - II )
~ - 5mm by changing the n eed le platr
5mm
i\11 important parts arc of plwsphcr bronze a ll oy also nilless nK•lal and ba ll bearings
Viscosity:
CS 20.62 at :{7.H( ·
Capacity: 800 - l,OOOcc.
2- Imm
DC X l ( :: 7, :: 9. ::11. ::1 - 1. ::1 6)
Push-button type. scak on fact• plate l'l'pn•scnts stitch length
By lc•,·cr moving in \'
l'rlical direction: gathering and slrl'lrh ing can bt· obtain ed
even in sew ing operation.
11 ppcr knife: L- shapc·d car bicil' 1 ip1wd
Lo\\'er kn ife: flat shrqwd ske l
Semi-submergl•d
Qf this mach in e, there arc the following S llh -ciasSt'S ;1\'aiJabil'.
Ty pe
' 0\'credging Blind·hemmin!-! I St•rging
1---
'
S ub-cl~ ss
. -
09C
11C
. - OIC
~
-
:\.laximum se\\:fng speed 6.500spm 6.500spm 5.500spm
----
---+
1'\eedle cooie/ Equipped Equipped Equipped
1'\o. of needle L
l\o. of threads t
:l :~ 2
Sewing width (Bightl
:3. 4. 5mm
3. 4mm 5mm
Needle
-~
DCX I OCx l I
>C <I
Height of pres~er f not
5m m 5m m :1mm
Stitch length I
mm -3.6mm lm m - 3.6mm lmm 5mm
Differential feed ratio
1.5 - 0.7 L1 - 0.i 1.2
tl.i
(gat h e rin ~·stretching)
-1 -
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2. Features
* The extensive design of various components and lubrication system and also the addition of the needle
cooler device on this machine assure the normal operation of maximum high speed of
6,500 stitches per ~
minute, without any troubles.
A) Combined lubrication system of forced lubrication by geared pump, sprash lubrication and oil wick
lubrication.
B) Unique design of needle bar mech;mism has lessend its weight as well as assures forced lubrication
to its every working part.
C) Exclusively designed over looper mechanism has made the use of light alloy possible and also ensures
smooth lubrication to the end.
D) Holders are made of dur<1lmin to decrease the weight. Main rods and bushings are made of phospher
bronze alloy.
E) Major moving
parts are perfectly lubricated inside the totally enclosed main body, so they will never
be exposed to outside dusts.
* The upper knife is L·shapecl to make the threading and replacement of the needle easy. Besides, the
carbide tip promises long durability of the knife.
* Stitch can be easily regulated by push-button, with the scale on the face plate, thus it is unnecessary to
change the eccentrics when you would like to change the stitch length.
* Differential feed can be easily adjusted hy the lever for gathering nr stretching without soiling yollf hands.
This also applies for the instantanem1s differentit~l adjustment ohtt~inahle.
* Ample space on the cloth plate allows easy sewing operation.
* Oil level in the oil reservoir is shown on the special oil gauge on the front side of the machine.
* Lubrication can be easily checked through the oil window in the top co\'er.
* Optional needle cooler emmres perfect sewing operation even with synthetic materials and threads at the
high speed of
6,500 stitches per minute.
* Colour combination of TAN-BEIGE is in well harmony with your modern factory. and operator's fatigue ~
can be lessened.
* As differential ratio can be adjusted upto 2.!i. this is suitadle for sewing of cloth which is ease to spread
such
as knitted fabric.
3. Operation
A. Sewing speed
Maximum speed of this machine is 6.500 stitches per minute. For the first 100 actual working hours. however.
the new machine should be operated
at about 5,000 s.p.m. so that all the working parts are well run-in.
After this running-in period, you may operate the machine
at maximum of 6,500 stitches per minutaninute.
This is desirable for machine's long life.
B. Motor, motor pulley and belt.
ll Use a clutch motor. 1/2 Hp, 2 pole, single or three phase. Our motor available is Models MD-344 (single
phase) and MD·354 (three phase).
2) Use M-type V -belt._
3) Machine speed (s.p.m.), diameter of motor pulley and length of motor belt is related to the following table.
Outside diameter of pulley and length of V-belt
Stitches per
50 "'
60 "'
minute Pulley V-belt Pulley V-belt
5,500
120mm 39 inch lOOmm
38
inch
6,000 130mm
39 inch llOmm 38 inch
6,500
140mm 39 inch 120mm
38
inch
2
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C. Setting up
This machine i ~ normally ~ct up as se mi -s ubmerged lyp e. Necessary parts and accessori es for set tin g up
lhis machi ne arc conta in ed together with the machine h ead.
If you have purchased this machine as head only. mak e table top as per attached table sheel. al so refer
to Fig. 1. which shows the parts necessary for sell in g up this machine and also the measurement to mounl
the bottom board lO the tab le as semi-submerged typ e.
With our Brother clutch motor. l\1oclels 1\ID-:~..t..t and MD-35-1. there is no anx ie ty lo se t the machine to the
bot tom board. ho\\'C\'Cr. if you would u se with other brand c lut ch motor. pl ease mak e s ur e to have prop er
holes
on the bottom board.
Jij , Center of V-belt
- 25 ; Screw for cushion b ase
"' I
:;;
I
~ I ::I
___ .....: r
* e, • .
d
-
2~7 -l
~
t "'
26i
Bolt hole for bottom board
l ...::-_
Collar for ~
I
Centre of bottom board
' machine pulley
I I
1 ~ Bottom board _
I
275 ~
(Fig. 1)
Figures are in
mitimeter
D. Oiling, draining and maintenanc e
(Fig. 2)
(Fig. 3)
Oil is drawn n ul of the machine pri or to it s shipment.
Before opera
tin g the mac hin e. therefore, remove the oil filt er cap
(shown in Fig. 21 and pour o il into lhe machinl' u si ng the funnel.
Oil lcn :l should he up to the upper lin e of the oil gauge sho "'n in
fig. 3.
Th e oil resen·oir consists of tw o tacks partilioned by a f ilt er so il
takes sometime before the o il levels of both lank match. Check if
o il is up to the required le\'el a littl e after the o il is poured. Add
o
il if o il le, ·el is below the upper li ne of the oil gauge. Be s ur e lo
check the oil gauge for oil level be for e opera tin g the machin e.
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(Fig . 4)
(Fig. 5)
( Fi g. 6)
E. Needle cool er dev i ce
When op era lin g- the machine for the
firsl ti me after un packing it ur after it
hm; been out of oil fo r a long period of
li me. add :> or 6 drops of oil into oi lin ~
point sho\\'11 in Fig. .] and Fi g. 5.
\" ou do not havc lo add oiI in to them
if tlw machim• is oper at ed d ail ~ · .
/\ l tlw L'nd cd' 100 al'lual hours operation. running- in period. change Llw
oil.
Tlwreaflcr.
dwnge it once in about Lhr Cl' mo n ths USl'. Th e quantity of
oil rcqu irL'd is about HOO- J.OOOcc. Hcmm·e the sere\\' sho\\·n in Fig. ti for
draining oi l.
The machine l'lnplnys a geared pump for l hL' forced lubrication to its
major mn,·i n).! parts. ll is recommend ed th at the oil rcscn ·oir be dis·
mmmled about 1 \\' i n• a YL'Hr for ck•an in g- of its imwr su rf ac<'s. pump. \\'in•
ga uzc. <'lc.
This is dt·si r:1 hi~· fqr lot i tg Ii fL· ui Ihe machiII<'.
\\ 'ith machinl' mock'! "·C". it is eq uipped with the needle cook r de,·i cc .
In order to get the good se\ring result on tlw r es in treated materials such as polyeste r. jersey. a nd tricot.
etc .. or \\'ith the sy nthetic threads. such as nylon <Jnd Dacron. it will be advantageous to usc the needle
cooler de,·ice.
1. Operati ng procedure
/T ank
I) i' <l Ur the siliwnc oil into the lank appro~imatelr -1 S 1 11 e<lp~ci tr
(:lOcc in capacity) then open th e cock sho\\'n in Fi g. 7.
2) If this machine is brand ne\\' or nftcr il has been oul of usc for long
time. it tak e~ about 10 -15 mmut es to sa tur ate the silicone o il into the
fe
ll on tl w needle guard. th en app ly several drips of si li co ne oi l on
the f c' lt so as to thoroughly sat urate before SC\\' ing operation.
:l) Th e cock 1111 1st bl' closed \\'hen the machim' do not re quir e lhc s ili cone
oi l. nanwly on the slo\\' sp~cd operation on cotton thread. cotton ma·
It-rials applit •d ancl also \\'hen rou do not use th<• machine.
(Fig. 7)
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2. Sewing capabi lity wit h needle coo ler
When you would sew the synthetic materials, jersey, tricot, elc., il can be ensured to sew upt o 6 plies of
suc h materials at the high speed of 6,500 st itch es per minute.
·3. Silicone oil to be used
Silicone oil ...... Yisco:.ity: 500 cs
50cc silicone oil co uld be operated apprn:--:imately half a month of sC\\'ing opera ti on alth ough it d epe nds
on the sewi ng work.
4. Pr o per installation on the ma ch ine
(Ft!i 8)
C D
I I
I I
5. Rem oval of the top cove r
1)
In sta llation of fe lt s upport a nd tube guid e
Felt support is installed on n ee dle guard front D as shown in
Fig . 8.
Tub e guide B should be in stalled on needle plate support deck with
fully in se rting the tube into th t- hole of the needle guard D because
th e tube C is fixt>d.
2) Posi tion of tank
Tlw position of tank s hould be se t up at the positicni th at ~he \' ent
hole is
higher than tht• oil l ev c•l as sh own in Fig. 7.
\\'hen you pull tlw tube Point I\ tn the l eft as
shown in Fig. 9. the tank and felt portions will
he
separated . thus th e tank can be cletatchable
L ogt•tht• r with top covt.•r.
(Fig. 9)
F. M ac hine oper ating d irect i on
The proper operating direction of this machine is clockwise as viewed from the pull ey side.
G. I nsta lli ng needle
,. <"'
{
1\.
(Fig. 10 )
Turn the pulley until the needle bar is raised tn
its high es t position, l owe r the lifter l eve r A
shown in Fig. 10 pressing by the thumb finger
and moYc presser foot arm R to the dir ec tion
as inclicalPd with arrow mark.
- !j -
Hole
'Needle set screw
(Fig. 11)
New, loosen the needle set sc rew and holding
the nee dle with its grooved side facing toward
you, th en insert the need le into the needle clamp
hole a ll th e way up ch ecking the ho le in the
needle c lamp whether the needle is all the way
up. After this c he ck . tighten the sc rew.
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H. Threading
Pass the threads through the eyes of cotton stand then please do in the following order;
(1) Under looper (2) Over looper (3) Needle
Before passing these thread, open the front covN, cloth plate,
and thread take·up coYer, turn the puHer
until the needle is at the highest position, and the pr~ger fnot arm outward. Pass the threads as shown
in Fig. 12.
When you threads to the eres of thread I{Uidcs. loopers and need!t•. pleaSl' usc with \h(' tweezer in the
accessory box.
Draw out the thread approximall' :icm from the tip of loop('r.
(Fig. 12A) (Fig. 128)
Two tl1reads Three threads
l:SECare should be taken for threading of two threads and three threads because diffpn•nccs between both
cases are existed as in Figure A and B.
!.Stitches
El3 for B956-0l Three threads overeding tension (Figure 13)
El3A for 8956-09 Three threads blind-hemming tension (Figure 1.Jl
E12A for 8956-11 Two threads serging tension (Figure !;))
El3 or E13A can be obtained \\'ith with readjusting the adjusting scrt>w.
El3A
(Fig. 13)
~.EJ:!A
(Fig. 14)
~El2A
(Fig. 15)
In <:ltst' of EJ:J, the needil' thrL•ad tension is the strongest then tlw under
looper thread tension and o\·er looper
thread tension is the \\'eakest.
In case of El:lA. tlll(kr looper thread tension is till' strongest. tht'n m·er
looper thread tension
an<\ the net•dle thread tension is the weakest
In case of El~i\. the needle thread tension is tht' wcakt>st. then the under
looper thn•;1d tension.
-6-
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J . Th read tens i on
Thread _ t ~ns i o n may change dcpcncling on the type of thr ead and material s se wn. s titch width, stitc h length.
lhe pos1t1<>n of the thread take-up and thr ead guides. If it shoulcl change considerabl y. make adjustment in
the following manner.
(Fig 1 6)
1. Adjustment of th read take-up
'['., tiJ.!htcn the needle thr ea d, lower the n ee dl e thread tak e- up.
To
loo~en il. rai se the take-up.
Th e thread tak <: ·up in tlw middle position is the standard thread
tension. (Fi g. ]())
Not e:
Thr ea d t ak e- up will be u se d in such way that thr ee thr ea ds
typ<.· ( Fi g ur e Al is for B9 56·01 and B9 56 -09, and tw o threads
Iype (Figure B) is for B 956- ll.
B
2. Adjusting looper t hr ead take- up an d th read guide
(Fig. 17 )
(Fig. 1B)
3. Adjusting thread tension screws:
t [
As sh ow n in Fig . 1 7. <H the hi gh est
pos iti on of the n eed le. it is the
standard p os iti on of the lo oper
thr e ad take-up and thread guide,
for thr ee thr ea ds u se . In this case.
th e position of under looper thr ead
guide shows in 13 is for cotton
thr ead and J\ for synthetic thr ead.
As sho wn in Fig . 18. al the highest
po ~ ition of the n eed l e. it is the
standard position of the looper
thread take-up and thr ead guide,
for the two threads us e.
Aft er completion of the abo,·e-memionecl adjustment of th e thread guides, and thread take-up, turn the thread
tension sere\\' for fin e adjustment. Incorporate an approp riat e adjustment for the above "Stitches'' (Page 14 ).
Be careful not to turn the screw in or o ut excess i, ·e ly. becau se it may tighten the threads more than
n ece !'sary or cau se the thread tak e- up lo f ee d thr eads too ex cess iv ely.
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K. Adjustment on the pre ss ure of presser foot: Installing or removing feed dog s:
and Height of feed dogs:
(Fig 19)
D
~·· ,;. ~ l·:-.:-.o....: t-l.il, ,;
~ c --- ,•
_ 1~ 1 )~ '
E B A
(Fig. 20)
(Fig. 21)
l. Adjusting stitch windth ( bight)
A (Fig.
22)
Lower knife
(Fig.
23)
The pr~.·~~urc of tlw presser foot can be adju!'tcd by menn!' tl( the
presser foo t adjust in~ scrL'\\' shown in FiJ.!. 19.
To install llw diffcrl•ntial feed do g :\ . ti !-{hte n the sc r ew JL
To in stall the main feed cloJ.! C and chaininJ.!·nff feed dog 1 11 .
tighten the
SCJ'l'\\' 1-:. (Fig. 20)
The standard height of the f eed clogs is such that when the nccdlr.
point comes
to fit perfectly to the lop surface of the needle plate
in its upward tra\'clling, the top of the feed clogs is l e\'C~l with the
surfa
ce of the ncc•dk plate. (Fi g. 2 1)
St it ch wtidth is dependent on cloth trimming \\'idth and the tongue
of the ncccllc plate.
Adjust the
trimmin~ width as follows: (Pig. 22)
1) Hemm·e the upper knife.
2) TiJ.!htcn the set sc rew A temporarily so that the lower kni.fe
mar come to the point where desired trimming width may be
obtained.
;{) Loosen the screw B and adjust the contact of the upper and
lower kni\·cs as shown in Fig. 23 by mm·ing the upper knife
holding block to eit her l eft or right.
..J) Tighten the screw B and in stall the upper knife whil e pressing
it to the I<J\\'Cr knife.
5) Loosen the set screw A and please make sure that the lower
knife may contact \\'ith upper knife by the spring pressure.
Fix llw low<'r knif<' by tiJ.!htening the ~et scr <'\\' A.
- R
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M. Adjusting stitch length
(Fig. 25)
(Fig. 24 )
St it ch length can be adjusted to any point w ithin th e rang e from 1. 7m m to 3.6 mm for s ub ·c l as~ ·O IC.
·09C.
and fro m 1.7mm to 5.0 mm for s ub ·c l ass ·IIC. At firs t. ope n the n ee dl e thr ea d tak e· up co\·er
A. (Fig. 2-l) T he n. with the push·bu l ton B loca ted in front of th e ma chine kept depressed. t urn th e butt on
gl>i ng inwa rd as the pulle y is turned.
St np the pu l le~· wht>n lhe poinler r eaches 1 he numb er re pr t·sent ing you r dl' sir ed s tit ch leng th. an d relea se
tlw push·button.
Th e numbers indicatL's tlw stitc h leng th. hm\ 'l'\'L·r. actual slill:h il •ngth may thange dependi ng 0 11 the l\ind of
lht' matt:ria ls. lhl'ir thick n l'ss and dificrc,ntial ft.'Pd in g.
N. Adjusting differential feed
(Fig. 26A )
Main feed link shaft
Main feed arm
(Fig.
269 )
Diff er ent ial feed m ay be acljust ecl to s tr etch be no rm a l or gathe r by l oose ning th e sc rew A sho wn in Fi g.
26A and moving the len~ r up or down as r eq uir ed. Normal feed is obta ined b ~ · setti ng th e le ver' s mark in
line ,, · ith th e ma rk on th e sca l e. If th e l eve r is lift ed up . nam ely to (- ) sign, you wi ll gel gat he rin g.
If cl own. lo (+ ) s ign. you "·ill gel st re tching. Afte r ad ju stment is co mplet ed. pl ease mak e s ur e to tight en the
sc rew sec ur e lr . In the case to r eq uir e la r ge r ga th e ring diff ere nti a l f ee d.
h~ e mo w clot h pl ate a nd feeding mechanism cove r. l oose n nut (f\ of main feed link s haft by an attach ed
\\Ten
ch. the n l owe r cl o wll\ntrd. (Figur e 26 B) Wh en th e main f ee d link s haft is lowered until bo tt o min g. the
diff ere ntial r at io \\'il1 become as fo 11ow s.
Di ffercnt ia 1 adj us ling lever . u ppe r e nd·········· · ···· Differentia 1 r al io. ~.5
Differe nti al adjusti ng lever. l owe r c nd····· ·········· Diff cre ntia l r at io. 1.: ~
\\'h en a m cd il l l11 differential ra tio is r equired . plac e and set t le th e mai n f ee d link s haft at an i nt e rm e diat e
p osititm in Iht• gr oovv of mai 11 fL't4d arm.
-9 -
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4. Adjustment
A. Height of needle (Fig. 27)
(Fig. 27)
For· needle replacement. please follow the chapter describing the
correct installation of the needle. When the needle is at the
highest position. the needle should be IOmm m·or the surface of
lhc needle plate.
B. Relation between needle and under looper
(Fig. 28A)
(Fig. 289)
(Fig. 28C)
EF4-B956-01 i 2mm
EF4-B956-09:
EF4-8956 ·-ll······t.Smm
(Fig. 280)
C. Installing needle guard rear
1/"'Nieedlllo guard rear
(Fig. 29A)
The tip of under looper and the center of needle will be aligned
where the needle is raised up 4 mm from the lo\\'er end.
(Figure 28A)
\Yhen the under looper is its left extremity, the distance hetm'en
the point of the under looper and the centre of the needle il-'
about 4 mm (Fig. 28B).
The under looper is determined itg height when it is inserted all
the way into the looper holder.
The relation between the point of the under looper ami the
IK'{'Clit• in its upward travelling is shown in Fig. 2HC.
Also <tt this time, installation will be made so as to provide nn
clem·ance between the needle scoop and the tip of under looper.
The under looper should be installed so as to he provided 2mm
nf inclination for B956-01 and 09, and 1.3mm of inclination fnr
B!-l.'lll-11 (Fig. :9-ID\.
I. Set the point of the under looper to the center axis of the
needle on its way up.
.
, In this condition, install the needle guard n•ar in such a way
that it mar lightly contact with the needle.
If there is too big space between the point of the under· looper
and the needle, there may be skip stitch caused, for which
please be careful enough not to bend
the needle by pushing it
with the needle guard.
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D. Installing needle guard front
(Fig. 298)
L Set the point of the under looper to the center axis of the
needle on its \\·a:-· up, same \\"a)' as in the case of the needle
~Lm rd n.•;u·.
~- In this condition. install the needle guard front in such a way
tlt;!l it \\"ill keep the space of apprux. O.lnun~0.2mm to the
nee£1\e.
E. Relation of needle with under looper and over looper (Fig. 30)
Over looper
After cletennining- the relative IJOsition of the needle and under
looper mentioned
in B. position the over looper properlr as
shown in FiR. :~o.
Needle must pass below bulge
on under
looper w!thout
contact {Clearance: About 0.1 mm)
Under looper·~/
4.5mm
-j
(Fig. 30)
(Fig. 31)
Fig-. :n shm\·s the nwasw·emt•nt of thC' o\'l'l" !nopC'r setting, fnr
y()ll\' refer£•nn•.
F. Installing and maintenance of knives (Fig:. :~21
//
,75" __
(Fig. 32)
--.- .
23'
Surface of
needle plate
1.4
-~~
I
'
\\
'90'-i-·~\
I
(Fig. 33)
:\lount the lo\\"er knife to the lower knife holder so that its edge
is len:>! with the needle plate. lnst;lll the upper l,:nife so that its
front edge
is O.:i-0.7mm bdow tlw L'dge of the lower knife \\'hen
it is at the lm\·est t'll<l of its stroke as shown in Fig. 32. The
upper knife is fii!L'd with ;1 tun).!:sten-carbide tip. which C<lll be
ground only \\'ith £1iamond \\·heL'I. It lasts its original sharpness
for a long period \\'ithout resharpening.
Sharpen the lower lmife
wlwn necessary. Fig. :n sho\\'S the sha11e of the lower knife.
- 11 -
From the library of: Superior Sewing Machine & Supply LLC

5. Trouble-shooting
A. Thread break
Cause
Poor thread quality.
Remedy: Use thread of good quality.
Cause
R,emedy:
Thread too thick for needle size.
Change needle or thread for the right one.
Cause Needle groove or needle eye poorly finished.
Remedy: Change needle for a good one.
Cause
Remedy:
Cause
Remedy:
Cause
Remedy:
Cause
Remedy:
Cause
Excessive pressure of tension disc.
Adjust to proper pressure.
Needle improperly fitted.
Refer to instruction for "Installing needle." (l'agt' :i)
Needle, looper, needle plate, or thread passage has flaws.
Smooth surface with oil stone or buff.
Relation of needle with looper and thread take-up not right.
Refer to
"Thread tension." !l'agt• /)
Wrong threading.
Remedy: Refer to "Threading."
!l'agl' lil
Cause Needle gt•ts hot.
Remedy: Use with needle cook•r
or u~ smaller sizt• m•edlt•.
B. Skip stitching
Cause
Remedy:
Cause
Remedy:
Cause
Remedy:
Cause
Remedy:
Cause
Remedy:
Cause
\~hong threading.
Refer to "Threading." (l'agc 6)
Point of looper out of shape.
Resharp with oil stone
or replace.
Needle point blunt
or bent.
Replace.
Needle improperly fitted.
Refer to "Installing needle." (Page 5)
Needle and needle guard out of proper relation.
Refer to "Installing needle guard." (!'age 10)
Needle gets hot.
Remedy: Use with needle cooler or use smaller size needle.
Cause
Remedy: Pressure of tension disc too small. Adjust to proper pressure.
C. Needle break
Cause
Remedy:
Cause
Remedy:
Cause
Remedy:
Needle and needle guard out of proper relation.
Refer to "Inst<J.lling needle guard." (i'age
\0)
Needle and looper out of proper relation.
Refer
to "Relation between needle and under looper" and "Helation of nee{1\e with under looper
and over looper." (\'age
10 & 11)
Needle bent.
Replace.
Cause Needle improperly fitted.
Remedy: Refer
to "Installing needle." (l'ag-e O'i)
- 12-
From the library of: Superior Sewing Machine & Supply LLC

D. Imperfect chaining-off
Cause : Wrong threading.
Remedy: Refer to "Threading." (Page 6)
Cause : Stitch tongue on needle plate has flaw.
Remedy: Smooth with emery paper and polish with buff.
Cause : Looper thread take-up and thread guide out of position.
Remedy: Refer to "Thread tension." (Page 7)
Cause : Chain feed dog improperly installed.
Remedy: Refer to "Adjustment on the pressure of presser foot: Installing or removing feed dogs: and Height
of feed dogs." (Page 8)
Cause : Thread too tight.
Remedy: Adjust to proper tension.
E. Improper thread tension
Cause : Relation of needle with looper and thread l<tke-up not right. ·
Remedy: Refer to "Adjustment" and "Thread tension." (Page 10 & 7)
Cause : Tension disc will not work properly.
Remedr: Clean tension disc of foreign particles to allow smooth operation.
Cause : Thread too thick for needle.
Remedy: Use needle or thread uf the right size.
Cause : \\'rong thre<tding.
Remedy: Refer to "Threading." Wag:e 6l
F. Poor trimming performance
Cause : Lower knife worn out.
Remedy: Re-sharpen. (Refer to "Fig. 33, Page II")
Cause : Upper and lower knives installed improperly.
Remedy: Refer to "Installing and maintenance of knives." /Page 11)
Cause : Spring pressure on lower knife not right for materials to be trimmed.
Remedy: Refer to "Installing and maintenance of knh•es." (Page II)
G. Irregular stitches
Cause : Wrong threading.
Remedy: Refer to "Threading."O'age 6)
Cause : Thread irregular in thickness.
Remedy: Use thread of good qualit~·.
Cause : Thread passages rough.
Remedy: Smoothly polish.
Cause Thread take-up and thread guide out of position.
Remedy: Refer to "Thread tension." ll'age 7)
Cause : Knives blunt.
Hemedy: Refer to "Installing and maintenance of knives." (l'age 11)
Cause : Lower knife installed improperly.
Remedy: Refer to "Installing and maintenance of knives." (Page II)
- 13-
From the library of: Superior Sewing Machine & Supply LLC

H. Excessive wrinkles along stitc;hes
Cause : Differential feed adjustment not right.
Remedy: H.efer to "AdjUsting differential feed.'-'(Pagc 9)
Cause : Pres.c;ure of presser foot not right.
Remedy: Adjust to proper pressure.
Cause : Thread tension tdo strong.
Remedy: Adjust properly.
Cause : Feed dogs installed improperly.
Remedy: Refer to "Adjustment on pressure of presser foot: Installing and removing feet: dogs: and Height
of feed dogs." (Page 8)
Cause : Knives blunt.
Remedy: Refer to "Installing and maintenance of knives." (Page 11)
Cause : Cloth trimming width and stitch tongue of needle plate out of proportion.
Remedy: Adjust trimming width to needle plate or replace needle plate.
Cause : Needle too thick.
Remedy: Use proper needle for materials and threa<l.
I. Needle produces to large hole
Cause : Needle point blunt.
Remedy: Replace needle.
Cause : Needle too large for material!'\.
Remedy: Use smaller size needle.
Cause : Needle gets hot.
Remedy: Use needle cooler.
- 14-
~-- J
From the library of: Superior Sewing Machine & Supply LLC

_,,
_,,
A--lK-
(;.4:1
i\:!11
il-?-1
•\-24
A~-
{;.;
(;.[1
A·.\.1!
PARTS LIST for EF4-B956C
INDEX
A_~;
•'...:!'
·':.:!:'
A M7
' •
fl-41
,,
" i\:"4K
,,.,c
11-"50>
-·'·'>;'
11-!;1
·'-"'
IH:'•
,,
"'
F.-67 1_1
''
c_~
1!-E;
C -:G 1!-11
' " IH~
''"
1!-7
I>· !II
'
2:1
E-:_19
_,,
E-:1.'<
' "
From the library of: Superior Sewing Machine & Supply LLC

- 9[-
._;
-._;
._;
'
lT
'
"
.,
"
')
,.
From the library of: Superior Sewing Machine & Supply LLC

A
11 12
95 l2
"
'
94
~ '~.;_,
m A,.,
85~ IJ
e>-a& ·-u
~,
PARTS LIST for
EF4~B956-01 C
-17-
From the library of: Superior Sewing Machine & Supply LLC

B
- 18-
From the library of: Superior Sewing Machine & Supply LLC