Juki LBH-761, LBH-762, LBH-763 Instruction Manual

MODEL

LBH-761-762

763

HIGH

STRAIGHT

industrial

SPEED,

BUTTON

sewing

Instruction

SI*

-v;

HOLING

machines

Book

•

TOKYO

-

JUKI

INDUSTRIAL

CO.,lTD

CONTENTS

I.

GENERAL

1.

Main

DESCRIPTION

OF

THE

MACHINES

specifications 1

2. Stitching types 2

II.

INSTALLATION

FOR

RUNNING

OF

THE

MACHINE

AND

PREPARATION

1. Installing the motor and the idler pulley 3

2. Installing the machine

3.

Rotating

4.

Installing

5.

How

to put on &

III.

HOW

TO

1.

Cleaning the

OPERATE

direction of pulley 6

the

chain

machine

remove

THE

arm

and

the

endless

MACHINE

bed 5

belt 7

2. Sewing speed 10

3.

Lubrication

4. Oiling the worm gears 13

5. Oiling the bevel gears 13

6.

Hand

oiling of other parts 14

7.

How

to insert

8.

Threading

9. Winding the bobbin

10.

Drawing

11.

Inserting
Running

12.

13.

Howtoprevent

14.

Slow speed running and how to stop the machine in

emergency

15.

How

to use the

the

needle

the machine 15

thread

out

the

the

the

thread

bobbin

machine

the

from the

case 18

cutting

bobbin

case 17

motionofknife 19

handle

Page

1

3

6

9

9

10

14

17

18

19

20

IV.

ADJUSTING

THE

VARIOUS

1.

The

bobbin

2.

The

needle thread tension 23

thread

tension 22

PARTS

22

3. Adjusting the take-up spring 25

4. Timing of the needle and the hook 26

5. Adjusting the positions of seam and barring in relation to

the

button

hole

6. Adjusting the clamp carrying motion 29

7. Changing the number of stitches 30

8. Adjusting the

9. Adjusting the

10.

Adjusting the bobbin thread trimmer blade 35

11.

Adjusting the pressure of the work clamp check 36

12.

Adjusting the installing angle of the button hole length

regulating shaft bell crank 36

13.

Adjusting the device to prevent the knife from cutting when

the

needle

14.

How to change the number of stitches at barred ends 38

15.

Adjustment of the tension releasing movement 38

16.

Adjusting the cutting timing of the knife 42

17.

Adjusting the amount of the presser bar lift 42

18.

Adjusting the stop-motion components 44

19.

Adjusting the belt tension 45

20.

Adjusting the bobbin winder 45

thread

positions

needle

breaks

of the

knife

thread trimmer blades 32

27

32

37

V.

MALFUNCTIONS

1. Defective stitching conditions

2.

3. Reasons for malfunctions other

VI.

MAINTENANCE

VII.

THE

adjustment of

Malfunctions

measures

and

corrective

DIMENSION

AND

thread

other

measures

OF

GRAPH

CORRECTIVE

and

MEASURES

reasons due to mal

tensions 46

than

THE

tension:

MACHINE

OF

reasons

than

THE

and

corrective

stitching conditions

INSTALLING

TABLE

46

48

49

51

52

I.

GENERAL

1.

Main

speciHcations

DESCRIPTION

OF

THE

MACHINE

JUKI
holing industrial sewing machines with a maximum sewing speed of
s.p.m. (standard speed

Models LBH-761, 762

2,500

s.p.m.)

and

763 are high speed, straight button

3,000

LBH-761

garments

2.5-4

mm (3/32"-5/32") while the length of the button hole (width of

knife)is6.5

of up to

Model

LBH-762.

is designed to button hole men's shirts,

and all

mm-19

1"isrequired

other

garments

and the

mm (l/4"-3/4"). When,

for

This

gowns,

model's

pajamasorladies'

barred

ends

width

however,

widthis2.5-5

blouses,

of the

barred

button holelength

suits,

use

mm

under

ends

JUKI

(3/32"-

3/16") [one side is 1.2-2.5 mm (l/16"-3/32")] and the length of the button

hole

is 6

mm—25.4

When a large button hole is required such as

Model

LBH-762

1 >/4".

can be changed within the range of

for these machines, at an extra cost, by which by

LBH-763.

but the length of the button hole (width of

Besides

The

Furthermore, an automatic attachment known as AO-1 is available

the above models, many sub-class models are available.

feeding

mm

(1/4"

—1").

This

model

has

the

same

and the driving are of gear

54—340

sweaters

barred

endsasthe

knife)

feed

type and the stitches

stitches.

just

stepping lightly

etc. use the

Model

is 1/4"—

on the treadle type switch, the work clamp check comes down automa

tically and the sewing can be started and as soon as the sewing is

completed, the

automatic

slightly altering the table.

work

attachment

clamp check automatically

can

be installed, on order, to the

goes

up. This special

LBH

table by

It is highly recommended that the high speed feature ot these models

be advantageously utilized together with the automatic attachment AO-1

to increase the button holing production of your plant.

is

2.

Stitching

1)

types

Namesofstitching

types

As in the case of zigzag lockstitch sewing by a zigzag machine,

these machines can do
appears only on the front surface of the sewing cloth
thread appears in a zigzag form on the back of the sewing garment.

"whip

stitching"

— 2 —

by which the needle

and

the bobbin

thread

Another

which

passes

the

bobbin

of

men's

2) Typesofstitching

Purl

With

these

stitchedtomake

ends can be purl stitched also.

"Whip

the

thread

II

typeofstitchingiscommonly

the

needle

straight

thread

through

tensionisstrengthened

the upper

threadisinterlocked,asin

shirts.

stitching"

machines,

is

eveninpurl

the

ends

appliedtogeneral

sturdier.

stitching"isgenerally

tension,

the

purl

stitching

INSTALLATIONOFTHE

called

"purl

and

the

center

However,ifyousodesire,

used

part of the

the

caseofbutton

stitching,

for

knit

fabric

the

goods

stitch

except

barred

but

canbeconvertedtowhip

MACHINE

stitching"

needle

hole

ends

by

thread

and to this

stitching

knit

goods.

are

the

barred

changing
stitching.

AND

by

whip

PREPARATION

1. Installing the motor and the idler pulley

As

shown

motor components ®. The head of the installing base bolt(Dshould come

out on the top surface of the table through the hole in the table.

Insertamotor

Install

the

motor

Appropriate

in

Fig.1,turn the table up side down and connect all

cushion(Dbetween

the

motorbyloosening

installing

bolt

power

(§)

for

from

this

FOR

the

the

motor

the

side

of the

machineisa

- 3 -

RUNNING

installing

adjusting

base

motor

300W,3-phase

and the

nut

base

(g)

and

(lower)

table.

pass

(5).

electric

Fig.

1

induction motor

phase

currentisavailable,

motor

(1,500

The

motor

long

hole

50"^,

the motor should be installed so that the installing bolt

nearly

the motor

by

Also,

50°o,

install so that the installing bolt

to the

pushingitfully

when

install the

When

The

reasons

tionsasexplained

(1,500

r.p.m./50oo,

r.p.m./50'^,

installing

but if the

1,800

hole

motor

centerofthe

pulleyof2,500

motor

motorbypushingitfully

2,800

r.p.m.

for installing the motor to the different,

toward

pulley

or

above

r.p.m.

the

of

3,000

are

1,800

r.p.m./60°o),

usea300

r.p.m./OO*^).

at the

W or

bottom

pulleyof2,500

long

hole

under

is to be

opposite

2,800

r.p.m.

comes

because

_ 4 —

usedat60°°,

direction

r.p.m.or3,000

pulley

to the center of the long

when

250Wsingle

of the

r.p.m.

the

from

toward

is to be

the

size

but

motor

speed

motor

r.p.m.isto be

the

of the

when

is to be

base

install

the

arrow

only

phase

base

(lower).

the motor

arrow

direction.

direction.

used

respective

motor

single

electric

(D

is a

used

comes

used

at

GO'H',

hole.

posi

pulley

at

If

at

is

changed,

motion

standard

accordingly.

Please note also

3-phase or single phase motor, use a motor base

when a steel frame motor is to be used, use a motor base

When a National Brand

used, the motor installing position is different, so be careful.

The idler pulley components @ should be installed to the bottom

surface

installing

baseofthe

motor

each

other.

2.

Installing

ihe

bell

device.

in

For this

installing

of the table by

hole

is rather

head

part and the

pulley

@

the

should

machine

should

not

contact

reason,

the

motor

that

when cast frame

single

hexagonal

large,besure

positionsofthe

be so adjusted that

arm

and

either

the

head

partorthe

follow

and

phase electric motor of

bolts

the

foregone

adjust

the

motor

B-7101-761-AAO

(§)of15/64",

method

respective

is used with

B-7101-761-BAG.

250

W is to be

Fig.

1.

that the belt is not contacting the

idler

bed

they

pulley

will

® and the

not be

stop-

as the

positions

either

and

As

the

touching

Turn the table

(A),

place the felt pads ® in line with the

install the

machine

Hook up the

is

attached

chain and let it hang down.

As

base, insert the hinge arm

interlock

guard

Caution

After

screw in the following manner: (Fig. 2 B)

Verify

lever

to the back of the machine bed

showninFig.2(A),

this

with the hinge at the rear

the

that the

(J)

toward

over

in an upright

arm ® on top of it.

S-shaped

with

the

hinge

machine

arm is installed, adjust the starting

machineisin

the

rear.

position

latch on the starting lever

place

the

machine

(3)

to the hole on the left side of the bed and

shaft

bushing

endofthe machine bed.

stop

Then,

loosen

- 5 -

and, as

4~70

showninFig.

holes

of the table and

(Fig.5(A)(D)

and

to this connect the shorter

head on top of the head

®.

position,

nut ® and

Lastly,

then

install

push

adjust

which

the belt

lever

set

the starting

so

that

2

the clearance between the bushing

lever

3.

becomes

Rotating

0.5~lmm.

direction

of

pulley

(2)

and set screw(Dof the starling

As viewed from the operator's side, the rotating direction of the pulley

is

clock-wise.

4.

Installing

the

chain

See Fig. 2 (A) on how to put on the chain.

First, fix the height of the table so that the

easily.

Then adjust the length of the chain and set the angle of the

vvork

can be performed

pedal to make the sewing easier.

- 6 -

5. How to

We have changed the belt for LBH-760 Series machines from the conventional round leather

belt

to the conventional leather belt and the running sound and dirtyness are much

Place

wouldbeeasier

(3)

Liftupthe

pass

the latch B (J).

put

to that of

the

machine

the

belt

on & remove the endless

endless

round

belt.

This

head

on the

machine

if the belt is put on

latch

tripping

between

the

before

lever

(5)

latchA(D

round

endless

base

the motor

and

and

belt

belt is

far

superiorindurabilityascompared

minimized.

and

put

this

belt

on in the

pulleyisinstalled

1.

Remove

hinge screw ® and the stop motion lever

tension spring suspension (D

2. First,

follows:

(1) Insert the belt for low speed (3) to the

low speed part of the belt shifter

(2) Raise up the machine

and

(4) Pass the belt through the space between

the starting lever adjusting screw (8) and

the

the starting link

put

on the belt for low speed (3) as

tilt

the

machine

machine

base

(9).

following

to the

head.

motor)

head

driving

support

order:

rod set

®.

rod

(It

i

(5) Pass the belt through the space between

the

bottom

bearing

part of the starting lever

bracket

(0 and top of the

table

3.

Put

same

4. Pull

on the

manner

out

belt

for

high

speed

asthe beltfor lowspeed®.

the

belt

from

the table down-

© in

the

K

5. Raise up the machine head and install

back the starting link driving rod set hinge

screw ® and the stop motion lever ten

sion

spring

positions.

6.

Install

Be

frontofthe

the motor

certain

suspension

that

motor

the

(D in their

pulley

two

pulley.

m

(I|)

to the motor.

belts

cometothe

original

After putting the belt for low speed @

and the belt for high speed @ to the

motor

pulley and the idler pulley, adjust

the position of the motor @ to right or

leftsothat

the starting lever
the base

the

belt

will

bearing

(Q'

of Ihe idler pulley.

notbecontacting

bracket ® or

Following

For
For

are the part

low speed
high

speed

numbers

B-7119-761-A00

B-7U9-761-C00

of the

endless

belt:

For
For

low
high

speed

speed

B-7119-761-BOO

B-7119-761-DOO

TENSION

The

ideal

(urethane belt)

3-4%

stretched

To

adjust

OF

THE

tensionofthe

would

condition.

it to

this

condition,

ENDLESS

endless

be to

operateitwith

catch

round

the

ROUND

belt

belt

BELT

(shorter one) for low speed running to the

pulleyofthe

in the figure, when the

(without

pulled
pulley), determine the position

so

that

the

extreme

center

(7/8"-61/64").

Then,

put

pulley. In this condition, adjust the tension

machine

head

bottom

andasshown

end

catching the belt to the idler

of

the

distance

bottom

of

the

motor

between

endofthe

comesto22-24

the

the

center

belt

on the low speed and high speed

is lightly

motor

and

the

mm

of

belt

of

correctly to the

the high speed

motor

beltsothat

pulley

and

the idler

it will beofsame

tension as the low speed belt. The tensionofthe high speed belt is adjusted by changing the

positionofthe idler pulley.

When the machine does not run with high speed, strengthen the tension of the belt.
When the belt does

or at

stop

strong or if

motion

not

time,

the

positionofthe

move from the driving pulley to the idler pulley at either starting time

(or

in vice>versa case)

belt shifter is

inspect

conectornot.

and

seeifthe

tensionofthe

beltistoo

To remove the belts, first, remove the rear side

belt

toward

the

outsideofthe

motor

pulley,

then remove the inside belt from the idler pulley, pass it through the grooveofthe pulley

out

and take it

clockwise (as viewed

toward the rear. At this position, if the

from

tlie rear), the

belt

will

come

off.

motor

pulley is rotated

counter

To replace the belts to the pulley, reverse this procedure by turning the pulley clockwise.

1.

Ill HOW TO

Cleaninj;

the

machine

OPERATE

THE

MACHINE

When you run the machine for the first lime, be sure to wipe away

all dust

and

rust-proof oil from all parts.

To produce alractive stitching job, the sewing hook must always be

cleaned

sticking to it. Iwery day after the work is through, tilt the machine

and

should

be

dust-free.

Also

— 9 -

seetoit

that

no

lint

hards

are

and

take

out

the bobbin case

from

the

surface

Also, remove all dust

check

and

the

needle

of

the

hook.

thread

and

and

dirt

trimmer

with a

from in

pairoftweezers remove all

and

blades.

When tilting the machine, at first, remove the belt

head

ing the
tilt it to your left. Be sure to see

support block at the left side of the machine (Fig. 12 ®),

that

the machine

standing up straight.

2.

Sewing

speed

around

arm

dirt

the work clamp

and

by upright-

support rod is

For the first 4 months, sew with a speed of

2,500

s.p.m. When the

machine is properly adjusted and oiled and the sewing cloth is not too

thick, the machine can be run at

sory box is for

2,500

s.p.m.

3,000

s.p.m. The pulley in the acces

butifyou desire a pulley of

2,800or3,000

s.p.m., please order separately as they are all available.

3.

Lubrication

J)

Oiling

From the oiling hole (Fig. 4 ®) pour in new

No. 1 (low viscosity) up to the red line of the oil sight gauge (Fig. 4

the

sewing

hook

JUKI

NEW Defrix Oil

(D).

Do not use high viscosity oil for these machines under any circumstances.

When the oil level drops below this red line, fill it up again to the

red line. The amount of oil to the sewing hook is adjusted by the screw

(Fig.5 (A)

However, it will take about

proper amount of oil is supplied to the

(D).

When this screw is screwed in, the oil supply becomes less.

10-^20

minutes after adjusting before the

sewing

hook.

So, don't hurry,

give it a plenty of time. If it's properly adjusted once, further adjust

ments would not be necessary. The sewing hook components should be

oiled

at

least

onceaweek.

2) Oiling the needle bar

Every morning open the oiling hole (Fig.

the new

JUKI

Defrix

Oil

and

the thread take-up

4®)

and drop in

No.

1. This is a

2~3ccof

special

oil

—

10

—

for

needle

oil leakage. Be careful.

3) Oiling the needle throw components

Every

5~8ccolJUKI
leak, so donl'l worry.

bar

components

morning,

NEW Defrix Oil No. I, The oil in this hole does not

open

only,soif

the

oil

you

hole

oil

too

(Fig.4@)

much,itmight

and

pour in

%/

cause

about

Fig. 5 (B)

) ®

(HJ

(10

4.

Oiling

the

worm

gears

The

worm gear components are lubricated by an oil reservoir, so

just change the oil once a year. To change the oil, remove screw (Fig.

5 (B)

(§))•

and

if

the

machine

is

tilted,

the

oil will flow

out

from

this

hole. After the spent oil is completely drained out, pour in about 70cc

of

New Defrix Oil No. 3 oil

5.

Oiling

the

bevel

If

the top cover (Fig. 4

gears

and

retightcn

(D)

is removed, the bevel gear case (Fig. 6

this screw

(§).

®) will appear. Remove the oil plug screw (Fig. 6 d)) and pour in

The

grease into this hole.

onceayear.

To

remove the cover, first, remove the tension release lever hinge

screw (Fig. 12

(T))

and

the operator. Then, remove the top cover set screws (Fig. 5

also remove the spur gear bushings (one at Fig.5 (B)@

greasing of this hole should be done at least

tilt the tension release lever (Fig. 12

and

one at @ below

(§))

towards

and

the spur gear). Finally, insert a screw driver to the slit of Fig. 12
and @ of the top cover and if it's lifted up evenly, the cover will

come

off.

When installing the top cover, push back the bobbin winder trip

latch (Fig. 5

(g>)

to the rear then by taking out the oil wick which is

dangling at the bottom surface of the top cover (the wick which is oiling
the shaft bushing of the bobbin winder pulley, Fig. 5 (B)@) from the bot

tom sideofthe oil hole (Fig. 4

leveling the top cover, plug it into the worm wheel shaft (Fig. 6 d))

the

cam

driving shaft (Fig. 6

arm.

Then,

after pegging in

retighten the top cover set screws

of

the

2 set screwsofthe

the

level surfaceofthe

between

the

rear

shaft

oil reservoir felt (Fig. 6 (D).

(D)

spur

and

<D)tothe

and

the

and

gear

top surfaceofthe

put

it on the top of the machine

cover position

install the

bushing

spur

should

tightened. Finally, insert

cover

and

and

pin

(Fig. 5 (B) d) ®)»

gear bushing. Each

be

matched

the

with

oil wick

by

(§)

—

13

—

6.

Hand

oilingofother

parts

Oil all other parts not mentioned above with the hand

oiler.

The

oiling holes are all marked with red paint. The main holes are shown

by arrows in Fig. 4, Fig. 5, Fig.12and Fig.

hand-oiled at least once or twice a week, a little
with

JUKI

NEW

Defrix Oil No. 1.

21.

These holes should be

quantity

N

at a time,

7.

How

to

insert

the

needle

Use

DPx5

(135x5) needle. Normally, size #14 is used lor men's

shins but depending on the size of the thread and the kind of sewing
fabric, select the right size of needle. For tricot
better use

"Super

DPx5

J"

which is a special needle for synthetic

fabrics because it will not damage the fabric. Generally, size

for purl stitching but for whip stitching,

used.

—14—

sizes

and

jersies, however,

#11

is used

up to#9may be safely

To insert the needle, put the grooved side of the needle toward the

operator, insert the

bar hole until it stops and then tighten it with the set

face

the

grooveofthe

8.

Threading

the

needle

deep up the

needlealittletothe

machine

needle

bar through the

lefttoprevent

screw.

skip-stitching.

needle

Better

-15