Singer 20U31 Manuale utente

Service

Manual

SINGER*

20u31/33/35

MACHINES

THE

SINGER

COMPANY

From the library of Superior Sewing Machine & Supply LLC - www.supsew.com

CONTENTS

Description

Sewing

Defects

and

Adjustments

To·Set

Needle

Bar

at

Correct

Height

Relation

Between

Needle

and

Rotating

Hook

To

Adjust

Sidewise

Movement

of

Needle

while

in

the

Material

(Zigzag

Stitching)

To

Adjust

Needle

Location

in

Relation

to

Needle

Hole

in

Throat

Plate

.

To

Obtain

Uniform

Straight

Stitch

To

Set

Feed

Dog

at

Correct

Height

To

Centralize

Feed

Dog

in

Throat

Plate

Slots

To

Set

Presser

Bar

at

Correct

Height

Timing

the

Feed

Positioning

the

Feed

and

Feed

Lifting

Eccentric,

Feed

Forked

Connection,

Feed Rock

Shaft

Crank,

Feed

Lifting

Rock

Shaft

Crank

Connecting

Rod

and

Feed

Lifting

Rock

Shaft

Crank

Adjustment

of

Tension

.

Adjustment

of

Backlash

,.. A

Trod~marlr

of

THE SINGER

COMPANY

Copyri9ht

O

1980

THE

SINGER

COMPANY

All

Rights

Aes.rn,ed

Throughout

the

World

Page

1

2

3

4

5

6

14

15

17

18

20

22

From the library of Superior Sewing Machine & Supply LLC - www.supsew.com

DESCRIPTION

Model

20U

artisan

machine

produces

top

quality

straight

and

zigzag

stitches

in

fabrics

as

fine

as

ladies'

lingerie

or

as

heavy

as

overcoating.

GENERAL

FEATURES

*

Rotating

hook

*

Link

take-up

*

Stitch

length

controlled

by

feed

regulating

dial

*

Needle

position

selector

places

stitching

in

left,

center

or

right

needle

positions

*

Spring

biased

stitch

width

selector

which

can

also

be

set

at

desired

stitch

width

SPECIFICATIONS

* Maximum

stitch

width

*

Maximum

stitch

length

*

Needle

bar

stroke

*

Height

of

presser

foot

from

top

surface

of

throat

plate

*

Thread

take-up

lever

stroke

*

Needle

bar

height

(Distance

from

throat

plate

seat

to

needle

stop

in

needle

bar

at

its

lowest

position)

*

Speed

-

up

to

5

mm

stitch

width

over

5

mm

and

up

to

maximum

stitch

width

*

Diameter

of

machine

pulley

(for

motor

drive)

- 1 -

9mm

5

s.

p.

i.

(5

sti

tches/25

.4

nnn)

34.8

mm

6.35

mm

63.5

mm

25.07

mm

2,500

r.p.m.

2,000

r.p.m.

75

mm

(3

in.)

From the library of Superior Sewing Machine & Supply LLC - www.supsew.com

SEWING

DEFECTS

AND

ADJUSHIENTS

ects

Need

le

Thread

Skip

Looping, Improper Uneven

Breakage Brec1kage

Stitching

Stagger

&

Feeding

Puckering

Zigzag

Noise

Place

of

Adjustmen~

Hitch

Stitch

Stitches

1. Thread -

X

-X

2.

Need

1e

X X X

X -X

X

3. Needle Bar X X

X ----X

4.

Rotating

Hook

-X X

----X

s.

Bobbin Case -

X

-X -X

6. Needle

Thread

Tension

-X -X X X

X

N

7. Thread Take-up Lever -

X

---

--X

8.

Presser

Foot X

X X

-

X

9.

Feed ----

X

X -X

10,

Throat

Plate

X

X --X

11. St i t ch

\~

i

cl

th X

12. Needle

Position

X

13,

Material

X

--- - X

X

14. Gear

-

------

X

From the library of Superior Sewing Machine & Supply LLC - www.supsew.com

TO

SET

NEEDLE

BAR

AT

CORRECT

HEIGlIT

OlECK:

1.

Remove

face

plate.

2.

Set

needle

position

selector

on

"center"

and

stitch

width

regulator

for

straight

stitching.

3.

Turn

machine

pulley

over

toward

you

until

needle

descends

to

its

lowest

position.

4.

Check

whether

upper

timing

mark

on

needle

bar

is

level

with

underside

of

needle

bar

timing

indicator

plate.

CAUTION:

The

needle

bar

timing

indicator

plate

has

been

correctly

positioned

at

the

factory

and

it

SHOULD

NOT

BE

DISTURBED.

ADJUSTMENT

:

If

needle

bar

is

not

set

at

correct

height,

then

adjustment

should

be

made

as

instructed

belm,.

1.

With

machine

set

for

straight

stitching

at

center

needle

pos1t1on,

turn

machine

pulley

until

ntedle

bar

is

at

its

lowest

position.

2.

Loosen

needle

bar

set

screw

so

that

only

the

needle

bar

will

move

up

and

down

freely.

3.

Move

needle

bar

up

or

down

as

required,

and

align

its

upper

t1m1ng mark

with

underside

of

needle

bar

timing

indicator

plate.

Then

securely

tighten

needle

bar

set

screw.

4.

Replace

face

plate.

Needle

Bar

Connecting

Stud

Fig.

1

- 3 -

Needle

Bar

Timing

Indicator

Plate

Needle

Bar

Set

Screw

Needle

BaT

From the library of Superior Sewing Machine & Supply LLC - www.supsew.com

RELATION

BETWEEN

NEEDLE

.AND

ROTATING

HOOK

A.

TO

TIME

TIIE

ROTATING

HOOK

CHECK:

1.

Set

needle

position

selector

on

"center"

and

stitch

width

regulator

for

straight

stitching.

2.

Turn

machine

pulley

over

toward

you

until

needle

rises

2.54

ma

from

its

lowest

position

and

the

lower

timing

mark

is

level

with

the

underside

of

needle

bar

timing

indicator

plate.

When

the

needle

bar

is

in

the

above

position,

the

point

of

rotating

hook

should

be

at

the

center

of

the

needle

as

shown

in

Fig.

2.

ADJUSTMEN1:

If

the

t1m1ng

of

rotating

hook

in

relation

to

the

needle

requires

correc-

tion,

make

adjustments

as

instructed

below.

1.

Set

machine

for

straight

stitching

at

center

needle

position.

2.

Remove

rotating

hook

shaft

bevel

gear

cover.

3.

Loosen

two

rotating

hook

set

screws

and

adjust

rotating

hook

as

required.

Retighten

set

screws.

'

Needle

'I

Hook

Point

;I

0.5

2.42

2.57

:

I:

I

4.25

:

I.

I

I '

I

2.54

r

'

' ' I

\j/

1.21

'I'

)'.

\I/

'j,c

'

Left

Needle

Position

Center

Needle

Position

Right

Needle

Position

Fig.

2

B.

~HECK

TIMING

OF

ROTATING

HOOK

AND

NEEDLE

(AT

LEFT,

CENTER

AND

RIGITT

NEEDLE

POSITIONS)

1.

Turn

machine

pulley

over

toward

you and make

sure

the

needle

is

free

from

any

interference

when

it

is

swung from minimum

to

maximum

bight

at

left,

center

and

right

needle

positions.

- 4 -

From the library of Superior Sewing Machine & Supply LLC - www.supsew.com

2.

Set

stitch

width

regulator

for

straight

stitching

and

check

(visually)

whether

the

relationship

between

needle

and

rotating

hook

is

as

shown

in

Fig.

2

(at

center

and

left

needle

positions)

just

when

needle

Tises

from

its

lowest

position.

3.

Be

sure

the

clearance

between

needle

and

hook

point

is

O -

0.05

mm

(Fig.

3)

regardless

of

left,

center,

or

right

needle

pasitions.

Excessive

clearance

may

result

in

skip

stitching.

Adjustment

should

be

made

in

the

same way

as

explained

in

paragraph

A,

"TO

TIME

THE

ROTATING

HOOK".

TO

ADJUST

SIDEWISE

MOVEMENT

OF

NEEDLE

WHILE

IN

TI-!E

MATERIAL

(ZIGZAG

STITCHING)

0 -

0.05

Hook

Point

Needle

Fig.

3

When

zigzag

stitching,

the

needle

must

not

move

sidewise

while

its

point

is

still

in

the

material,

or

in

the

needle

hole

in

throat

plate.

The-needle

should

make

its

upward

or

downward movement

only

after

completing

its

swing

to

the

left

or

right

as

shown

in

Fig.

4.

v v

l'

/ ' I '

✓'

/

";

'

.,

I ' ' /

I ' ,

~

'

--

'

/

' /

'

✓

' ,

I

\.

A I

\

,.

' I

I + " ~

,t

It-

I

I \

/ \

I '

A

, '

..

! '

I '

...

.,

• I

I '\ \ I

~~

Correct

Wrong Wrong

Fig.

4

Fig.

5-a

Fig.

5-b

If

the

needle

continues

its

swing

even

as

it

enters

the

needle

hole

in

throat

plate,

or

when

it

begins

to

rise

as

shown

in

Fig.

5-a

and

5-b,

such

condition

should

be

corrected

by

making

the

following

adjustments.

·-

5 -

From the library of Superior Sewing Machine & Supply LLC - www.supsew.com

ADJUSTMENT:

1.

Turn

machine

pulley

over

toward

you

until

needle

bar

is

at

its

lowest

position.

2.

Remove

screws

and

lift

off

arm

top

cover.

Loosen

the

zigzag

triangular

cam

shaft

collar

set

screw

and

slide

collar

toward

front

of

machine.

Check

whether

the

two

zigzag

triangular

cam

set

screws

(with

center

line

aligned)

are

located

parallel

to

the

bearing

face

of

the

zigzag

stitch

Tegulator

fork.

3.

If

the

triangular

cam

set

screws

are

not

located

parallel

to

the

bearing

face

of

the

stitch

regulator

fork,

loosen

arm

shaft

(horizontal)

worm

gear

set

screws

and

turn

arm

shaft

worm

gear

as

required

until

the

triangular

cam

set

screws

are

in

either

one

of

the

two

positions

shown

in

Fig.

6.

Then

securely

tighten

arm

shaft

worm

gear

set

screw.

4.

Check

rith

a

dial

gage

(Fig.

11)

to

see

whether

the

needle

is

still

making

sidewise

movement

while

in

the

fabric

and

below

throat

plate,

and

if

necessary,

readjust

as

instructed

above.

CHECK:

Zigzag

Triangular

Cam

Set

Screw

To

Be

Par

all

el

---\✓

---

Fig.

6

TO

ADJUST

NEEDLE

LOCATION

IN

RELATION

TO

NEEDLE

HOLE

IN

THROAT

PLATE

To

Be

Parallel

--'{

---

1.

Fit

needle

to

needle

clamp.

(Make

sure

the

needle

is

not

bent.)

2.

Set

needle

position

selector

on

"center"

and

stitch

width

regulator

for

straight

stitching.

- 6 -

From the library of Superior Sewing Machine & Supply LLC - www.supsew.com

4.

Turn

iaachine

pulley

slowly

until

needle

descends

into

the.needle

hole

in

throat

plate

(for

zigzag

stitching)

and

check

whether

or

not

the

needle

is

properly

located

in

the

center

of

the

needle

hole

(Fig.

7).

s. Change

throat

plate

to

straight

stitching

throat

plate,

lower

needle

hole

and

check

whether

it

is

properly

centered

or

not.

plate

to

zigzag

stitching

throat

plate.

needle

into

Change

throat

6.

Move

stitch

width

regulator

to

maximum

stitch

width

and

while

holding

regu-

lator

in

this

position,

turn

machine

pulley

and

check

left

and

right

needle

locations

in

relation

to

the

center

of

needle

hole

in

throat

plate.

Also

check

left

and

right

needle

locations

in

relation

Lo

the

needle

hole

with

need.le

position

set

at

left

and

right

of

center.

-

Center

~

l~

Fig.

7

Fig.

8

Fig.

9

ADJUSTMENT:

If

the

needle

location

is

offset

to

the

left

or

to

the

right

of

center

and

the

clearance

between

needle

and

edge

of

hole

at

left

and

right

is

not

equal,

or

if

needle

continues

to

swing

even

when machine

is

set

for

straight

stitching,

and

if

for

any

reason

it

is

necessary

to

replace

and

adjust

then

adjust

as

instructed

below.

A.

TO

ELIMINATE SIDEWISE

MOVEMENT

OF

NEEDLE

WHEN

MAO-HNE

IS

SET

FOR

STRAIGITT

STITOiING

1.

Fit

needle

plug

to

needle

clamp.

(Make

needle

plug

by

grinding

down

the

point

of

a

needle.)

Fig.

10

- 7 -

rr:2

i~=t

20

mm

From the library of Superior Sewing Machine & Supply LLC - www.supsew.com

2.

Loosen and Temove arm

side

cover.screws

..and.rernove

side

cover.

Remove

arm

top

cover

screws

and

lift

off

top

cayer.

3.

Set

needle

position

selector

on

"center"

and

stitch

width

regulator

for

straight

stitching.

4.

Turn

machine

pulley

over

toward

you and check

existence

of

sidewise

movement

of

needle.

(Fig.

11)

5.

If

there

is

a

sidewise

movement

in

the

needle,

loosen

bight

amplitude

stop

plate

(left)

set

screw

and move

left

bight

amplitude

stop

plate

(marked with

asterisk)

to

the

left

or

right

as

required,

until

the

sidewise

movement

is

eliminated.

(Fig.

12)

Check,

using

a

dial

gage

lFig.

11),

and

make

sure

the

sidewise

movement

(if

any)

is

held

to

less

than

0.05

and

securely

tighten

set

screw.

Needle

Bar Frame

Fig.

11

- 8 -

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