Singer 20U31 User manual

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

Correct

Height

Relation

Between

Needle

and

Rotating

Hook

Adjust

Sidewise

Movement

Needle

while

the

Material

(Zigzag

Stitching)

Adjust

Needle

Location

Relation

Needle

Hole

Throat

Plate

Obtain

Uniform

Straight

Stitch

Set

Feed

Dog

Correct

Height

Centralize

Feed

Dog

Throat

Plate

Slots

Set

Presser

Bar

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

Tension

Adjustment

Backlash

,.. A

Trod~marlr

THE SINGER

COMPANY

Copyri9ht

1980

THE

SINGER

COMPANY

All

Rights

Aes.rn,ed

Throughout

the

World

Page

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

DESCRIPTION

Model

20U

artisan

machine

produces

top

quality

straight

and

zigzag

stitches

fabrics

fine

ladies'

lingerie

heavy

overcoating.

GENERAL

FEATURES

Rotating

hook

Link

take-up

Stitch

length

controlled

feed

regulating

dial

Needle

position

selector

places

stitching

left,

center

right

needle

positions

Spring

biased

stitch

width

selector

which

can

also

set

desired

stitch

width

SPECIFICATIONS

* Maximum

stitch

width

Maximum

stitch

length

Needle

bar

stroke

Height

presser

foot

from

top

surface

throat

plate

Thread

take-up

lever

stroke

Needle

bar

height

(Distance

from

throat

plate

seat

needle

stop

needle

bar

its

lowest

position)

Speed

stitch

width

over

and

maximum

stitch

width

Diameter

machine

pulley

(for

motor

drive)

- 1 -

9mm

sti

tches/25

nnn)

34.8

6.35

63.5

25.07

2,500

r.p.m.

2,000

r.p.m.

in.)

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

SEWING

DEFECTS

AND

ADJUSHIENTS

ects

Need

Thread

Skip

Looping, Improper Uneven

Breakage Brec1kage

Stitching

Stagger

Feeding

Puckering

Zigzag

Noise

Place

Adjustmen~

Hitch

Stitch

Stitches

1. Thread -

-X

Need

X X X

X -X

3. Needle Bar X X

X ----X

Rotating

Hook

-X X

----X

Bobbin Case -

-X -X

6. Needle

Thread

Tension

-X -X X X

7. Thread Take-up Lever -

---

--X

Presser

Foot X

X X

Feed ----

X -X

10,

Throat

Plate

X --X

11. St i t ch

th X

12. Needle

Position

13,

Material

--- - X

14. Gear

------

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

SET

NEEDLE

BAR

CORRECT

HEIGlIT

OlECK:

Remove

face

plate.

Set

needle

position

selector

"center"

and

stitch

width

regulator

for

straight

stitching.

Turn

machine

pulley

over

toward

you

until

needle

descends

its

lowest

position.

Check

whether

upper

timing

mark

needle

bar

level

with

underside

needle

bar

timing

indicator

plate.

CAUTION:

The

needle

bar

timing

indicator

plate

has

been

correctly

positioned

the

factory

and

SHOULD

NOT

DISTURBED.

ADJUSTMENT

needle

bar

not

set

correct

height,

then

adjustment

should

made

instructed

belm,.

With

machine

set

for

straight

stitching

center

needle

pos1t1on,

turn

machine

pulley

until

ntedle

bar

its

lowest

position.

Loosen

needle

bar

set

screw

that

only

the

needle

bar

will

move

and

down

freely.

Move

needle

bar

down

required,

and

align

its

upper

t1m1ng mark

with

underside

needle

bar

timing

indicator

plate.

Then

securely

tighten

needle

bar

set

screw.

Replace

face

plate.

Needle

Bar

Connecting

Stud

Fig.

- 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

TIME

TIIE

ROTATING

HOOK

CHECK:

Set

needle

position

selector

"center"

and

stitch

width

regulator

for

straight

stitching.

Turn

machine

pulley

over

toward

you

until

needle

rises

2.54

from

its

lowest

position

and

the

lower

timing

mark

level

with

the

underside

needle

bar

timing

indicator

plate.

When

the

needle

bar

the

above

position,

the

point

rotating

hook

should

the

center

the

needle

shown

Fig.

ADJUSTMEN1:

the

t1m1ng

rotating

hook

relation

the

needle

requires

correc-

tion,

make

adjustments

instructed

below.

Set

machine

for

straight

stitching

center

needle

position.

Remove

rotating

hook

shaft

bevel

gear

cover.

Loosen

two

rotating

hook

set

screws

and

adjust

rotating

hook

required.

Retighten

set

screws.

Needle

Hook

Point

0.5

2.42

2.57

4.25

I '

2.54

' ' I

\j/

1.21

'I'

)'.

\I/

'j,c

Left

Needle

Position

Center

Needle

Position

Right

Needle

Position

Fig.

~HECK

TIMING

ROTATING

HOOK

AND

NEEDLE

(AT

LEFT,

CENTER

AND

RIGITT

NEEDLE

POSITIONS)

Turn

machine

pulley

over

toward

you and make

sure

the

needle

free

from

any

interference

when

swung from minimum

maximum

bight

left,

center

and

right

needle

positions.

- 4 -

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

Set

stitch

width

regulator

for

straight

stitching

and

check

(visually)

whether

the

relationship

between

needle

and

rotating

hook

shown

Fig.

(at

center

and

left

needle

positions)

just

when

needle

Tises

from

its

lowest

position.

sure

the

clearance

between

needle

and

hook

point

O -

0.05

(Fig.

regardless

left,

center,

right

needle

pasitions.

Excessive

clearance

may

result

skip

stitching.

Adjustment

should

made

the

same way

explained

paragraph

"TO

TIME

THE

ROTATING

HOOK".

ADJUST

SIDEWISE

MOVEMENT

NEEDLE

WHILE

TI-!E

MATERIAL

(ZIGZAG

STITCHING)

0 -

0.05

Hook

Point

Needle

Fig.

When

zigzag

stitching,

the

needle

must

not

move

sidewise

while

its

point

still

the

material,

the

needle

hole

throat

plate.

The-needle

should

make

its

upward

downward movement

only

after

completing

its

swing

the

left

right

shown

Fig.

v v

/ ' I '

✓'

I ' ' /

I ' ,

' /

✓

' ,

A I

' I

I + " ~

It-

I \

/ \

I '

, '

! '

I '

...

• I

I '\ \ I

Correct

Wrong Wrong

Fig.

5-a

Fig.

5-b

the

needle

continues

its

swing

even

enters

the

needle

hole

throat

plate,

when

begins

rise

shown

Fig.

5-a

and

5-b,

such

condition

should

corrected

making

the

following

adjustments.

·-

5 -

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

ADJUSTMENT:

Turn

machine

pulley

over

toward

you

until

needle

bar

its

lowest

position.

Remove

screws

and

lift

off

arm

top

cover.

Loosen

the

zigzag

triangular

cam

shaft

collar

set

screw

and

slide

collar

toward

front

machine.

Check

whether

the

two

zigzag

triangular

cam

set

screws

(with

center

line

aligned)

are

located

parallel

the

bearing

face

the

zigzag

stitch

Tegulator

fork.

the

triangular

cam

set

screws

are

not

located

parallel

the

bearing

face

the

stitch

regulator

fork,

loosen

arm

shaft

(horizontal)

worm

gear

set

screws

and

turn

arm

shaft

worm

gear

required

until

the

triangular

cam

set

screws

are

either

one

the

two

positions

shown

Fig.

Then

securely

tighten

arm

shaft

worm

gear

set

screw.

Check

rith

dial

gage

(Fig.

11)

see

whether

the

needle

still

making

sidewise

movement

while

the

fabric

and

below

throat

plate,

and

necessary,

readjust

instructed

above.

CHECK:

Zigzag

Triangular

Cam

Set

Screw

Par

all

---\✓

---

Fig.

ADJUST

NEEDLE

LOCATION

RELATION

NEEDLE

HOLE

THROAT

PLATE

Parallel

--'{

---

Fit

needle

clamp.

(Make

sure

the

needle

not

bent.)

Set

needle

position

selector

"center"

and

stitch

width

regulator

for

straight

stitching.

- 6 -

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

Turn

iaachine

pulley

slowly

until

needle

descends

into

the.needle

hole

throat

plate

(for

zigzag

stitching)

and

check

whether

not

the

needle

properly

located

the

center

the

needle

hole

(Fig.

7).

s. Change

throat

plate

straight

stitching

throat

plate,

lower

needle

hole

and

check

whether

properly

centered

not.

plate

zigzag

stitching

throat

plate.

needle

into

Change

throat

Move

stitch

width

regulator

maximum

stitch

width

and

while

holding

regu-

lator

this

position,

turn

machine

pulley

and

check

left

and

right

needle

locations

relation

the

center

needle

hole

throat

plate.

Also

check

left

and

right

needle

locations

relation

the

needle

hole

with

need.le

position

set

left

and

right

center.

Center

Fig.

ADJUSTMENT:

the

needle

location

offset

the

left

the

right

center

and

the

clearance

between

needle

and

edge

hole

left

and

right

not

equal,

needle

continues

swing

even

when machine

set

for

straight

stitching,

and

for

any

reason

necessary

replace

and

adjust

parts,

then

adjust

instructed

below.

ELIMINATE SIDEWISE

MOVEMENT

NEEDLE

WHEN

MAO-HNE

SET

FOR

STRAIGITT

STITOiING

Fit

needle

plug

needle

clamp.

(Make

needle

plug

grinding

down

the

point

needle.)

Fig.

- 7 -

rr:2

i~=t

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

Loosen and Temove arm

side

cover.screws

..and.rernove

side

cover.

Remove

arm

top

cover

screws

and

lift

off

top

cayer.

Set

needle

position

selector

"center"

and

stitch

width

regulator

for

straight

stitching.

Turn

machine

pulley

over

toward

you and check

existence

sidewise

movement

needle.

(Fig.

11)

there

sidewise

movement

the

needle,

loosen

bight

amplitude

stop

plate

(left)

set

screw

and move

left

bight

amplitude

stop

plate

(marked with

asterisk)

the

left

right

required,

until

the

sidewise

movement

eliminated.

(Fig.

12)

Check,

using

dial

gage

lFig.

11),

and

make

sure

the

sidewise

movement

(if

any)

held

less

than

0.05

and

securely

tighten

set

screw.

Needle

Bar Frame

Fig.

- 8 -

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