Singer Centurion 121D User manual

SINGER

121D,121C

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

Form

21624

(Rev

977)

I UAL

I *

Sewing l\llachine

121D CLASS

121C CLASS

1976

The

Singer

Company

All

Rights

Reserved

Throughout

the

World

•A

Trademark

of THE SINGER

COMPANY

Printed

in U.S.A.

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

LUBRICATION

Moving

parts

have

either

permanently

sealed

pre-lubricated

ball

needle bearings

oil

impregnated

bushings

which

require

no manual

lubrication.

The

following

exceptions

are:

HOOK

An oil

reservoir

supplies

oil to the

sewing

hook race and is

filled

through the oil

cup

shown,

with

Singer

Type

"C"

oil,

until

the word

"MAX"

is seen in the

indicator

window.

Check

oil level at

indicator

window

daily

before

starting

machine. As oil level decreases,

red

arrow

will

appear

(Fig. A).

-------------------------------

FIG. A

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

TO TEST HOOK LUBRICATION

Thread

machine

and

sew

yards

scrap

material.

Pay

attention

stitch

quality

amount

oil

this

time.

Remove

material

and

bed

slide.

Run

machine

approximately

one

minute

establish

uniform

oil

flow.

Without

stopping

machine,

hold

piece

paper

place

under

hook

for

seconds.

Remove

paper

and

compare

oil

pattern

with

Fig. B

for

proper

oil

flow.

•,

·,'

....

...

. .

. . .

•

•-I,

FIG. B

there

trace

oil

excess,

adjustment

should

made

with

the oil

metering

screw.

order

gain

access

to oil

metering

screw,

the

hook

should

position

shown

in Fig.

Turn

oil

metering

screw

clockwise

for

oil

and

counterclockwise

for

less

(Fig. D).

Normal

setting

made

turning

the

metering

screw

all

the

way

and

then

backing

the

screw

turns

out.

less

turns

may

required

depending

the

operation

being

performed.

Oil

Metering

Screw

Oil

Metering

Screw

Oil Less Oil

FIG. C FIG. D

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

If oil flow is not satisfactory, remove hook

assembly

and oil filter.

Check

filter. Oil

wick

should

be replaced

whenever

it has

become

clogged with

lint

or dirt.

excess

of oil

sometimes

indicates

that the

filter

wick

has become

detached

from the

screw

or the

screw

is not

securely

tightened.

Inspect

all oil passages to see they have not become

clogged.

011

Filter~

...

:·/•/•'

---

Wick

Hook Assembly

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

l .

MACHINE

THREADING

Move

take-up

eyelet

its

highest

point.

Lead

thread

from

thread

stand

through

thread

post

atop

machine

arm

Through

eyelets

thread

guard

Units

with

U.T.T.,

through

pretensioner

Down

through

thread

retainer

Into

and

around

tension

assembly

Over

check

spring

and

under

slack

thread

regulator

and

through

thread

retainer

and

take-up

eyelet

Down

through

thread

retainers

(2)

10.

Through

needle

bar

thread

guide

11.

Through

needle

eye

from

left

right

ioner

For

Units

with

Underbed

Thread

Trimmer

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

STITCH

LENGTH

The

stitch

length

can

regulated

while

the

machine

is in

operation

obtain

the

desired

stitch

length

forward

feed,

turn

regulating

thumb

screw

on oil

pan

"in"

(coun-

terclockwise)

for

less

stitches

per

inch,

and

"out''

(clockwise)

for

more (Fig.

adjust

the

stitch

length

for

reverse

feed, it is

necessary

that

the

reverse

stopping

block

properly

positioned

This

done

loosening

the

lock

screw

in the

stopping

block

and

sliding

the

slide

block

down

to the

desired

stitch

length

The

locking

screw

must

then

retightened

(Fig.

Regulating

Thumb

Screw

--~'.

Less

FIG. A

Stitch

Length/

,,~'

~'t.-~

Regulating

Screw

IRB,,

i!tit•J

•I

FIG. B

FIG. C

PREVENTING

UNAUTHORIZED

CHANGES

STITCH

LENGTH

prevent

unauthorized

changes

stitch

length

remove

the

retainer

plate

screw

and

take

out

the

retainer

plate

spacer.

Replace

and

tighten

the

retainer

plate

screw

(without

spacer)

which

will

lock

the

retainer

plate

against

the

stitch

regulating

gears

(Fig. C)

ADJUSTABLE

STITCH

LENGTH

STOP

adjustable

stitch

length

stop

provided

prevent

the

machine

from

making

stitches

longer

than

pre-determined

maximum.

adjust

the

stop,

set

the

machine

desired

stitch

length

previously

instructed

and

turn

stop

screw

until

bottoms

against

the

stitch

length

regulating

screw

Lock

stop

screw

place

with

stop

screw

nut

(Fig.

Stitch

length

setting

should

NEVER

EXCEED

capacity

fittings

in use.

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

PRESSER

FOOT

PRESSURE

The

pressure

the

material

should

light

possible

while

still

sufficient

to.ensure

correct

feeding

There

are

two

regulating

screws

that

control

the

presser

foot

pressure

One

atop

the

arm

and

one

the

rear

the

machine

The

one

atop

the

arm

the

major

control,

normally

adjusted

prior

long

production

runs

new

applications

For

day-by-

day

casual

adjustments,

the

regulating

screw

the

rear

used.

screwing

for

less

pressure

and

unscrewing

for

pressure

When

this

rear

screw

unscrewed

all

the

way

out,

disengages,

only

then

can

the top

screw

applied.

and

serves

the

sole

control

until

the

rear

screw

again

turned

inward

(Fig

Regulating

Screw

B when

c.---c

Screw

Disengaged -

:::=::

Regulating

Screw

0 0

FIG. A

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

HOOK TIMING

Proper

clearance

between needle

and

hook point, re-

quires

that the point of the hook

should

pass the nee-

dle

closely

possible

without

striking

deflect-

ing it. There

should

.003"

.005"

clearance

bet-

ween the

two

(Fig. A).

adjust

clearance,

loosen

bushing

set

screw

(Fig.

B).

With

screwdriver

placed

shown

move

entire

hook

and

bushing

(Fig. C).

Tighten

bushing

set

screw.

Hook Bushing

Set Screw

FIG. B

Insure

that

the

needle

guard

prevents

the

needle from

contacting

the

hook

point

any

time. If large needles are to be

used

may be

necessary

string

the

needle

guard

back

allow

hook

point

closer

needle

(Fig.

D).

FIG. C

Needle Guard

FIG. D

.003

.005

Flat of

Hook Point

To Needle

FIG. A

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

HOOK

TIMING

CONT'D

Reset

position

finger

there

.018"

.022"

thread

clearance

between

finger

and

basket

(Fig. E).

FIG. E

For

200

Variety Machines

(.085"

Loop Rise)

Loosen

hook

set

screws.

Turn

hand

wheel

direction

rotation

until

needle

bar

is on

the

rise

stroke

and

the

lowest

mark

aligned

with

the

needle

bar

height

indicator

Set

hook

point

the

centerline

of the

needle

(Fig.

Tighten

hook

set

screws.

FIG. F

Hook

Point to

Centerline of Needle

For

300

Variety

Machines

(.100"

Loop Rise)

Loosen

hook

set

screws.

Turn

hand

wheel

direction

rotation

until

needle

bar

the

rise

stroke

and

the

center

mark

aligned

with

the

needle

bar

height

indicator.

Set

hook

point

the

centerline

of the

needle

(Fig.

Tighten

hook

set

screws

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