Singer 620 User manual
SINGER
CLASSES
620,
625,
626
AND
628
Supplement
to
Form
20732
.
Machines
620,
625,
626
and
628
'
(1066)
SINGER
SERVICE
MANUAL
MACHINES
OF
CLASSES
620,
625,
626
AND
628
Instructions
appearing
in
the
Service
Manual
for
Machines
of
Class
600
generally
apply
to
Machines
of
Classes
620,
625
and
626.
Instructions
for
Class
603
Machines
generally
apply
to
those
of
Class
628.
This
supplement
provides
instructions
which
apply
only
to
Class
620
625
626
and
628
Machi
nes.
THE
SINCER
COMPANY
*
A
Trademark
of
THE
SINGER
COMPANY
Insert
in
Form
20732,
Swing
Needle
Service
Manual
Printed
in
U.
S.
A,
INDEX
Bobbin
Driver
Adjustment....
Removal
and
Replacement..—.
Bobbin
Push-Button
Removal
and
Replacement__—.---
Chainstitch
Adjustments.........
Hinge
Assembly...-.
Hoolc,
Rotating
Positioning...-.
Removal.
Replacing...-.
Timing...
Inspection
and
Lubrication...—.....
Needle-Threader
Storage
and
Use...
Selector
Systems
Release
Mechanism..
.
....—-
The
Cam
Stack...-.-
Bight-Amplitude
and
Pattern
Selector.
Needle-Bar
Driving
Arm.
Tension,
Needle
Thread
Adjustment.
Removal
and
Disassembly.
Reassembly
and
Reolacement.
Throat-Plate
Position
Bracket
Remove
i
ana
R
ss
icc
oment.
Winding
Mechanism.
•Viring
Dicgram.
9
9
9
20
5
8
6
6
7
3
22
12
14
17
19
10
10
10
PROPERTY
OF
THE
SINGER
COMPANY
This
is
a
private
and
confidential
communication
to
and
for
the
use
only
of
the
employees
of
The
Singer
Company
and
its
affiliated
companies.
Reproduction,
sale,
distribution,
or
publication
thereof
to
the
public
is
forbidden.
2
INSPECTION
AND
LUBRICATION
Before
any
extensive
inspection
is
undertaken
to
find
causes
of
faulty
operation,
the
machine
should
be
thoroughly
cleaned
and
lubricated.
Remove
lint,
fluff,
dust
or
other
foreign
particles
from
the
hook,
feed
dog,
and
bobbin
case.
Remove
bobbin
case
and
clean
in
varsol.
Open
face
plate
and
clean
out
lint
or
waste
collected
around
needle
bar,
presser
bar,
and
pressure
regulator.
CLASS
620,
625
and
628
MACHINES
Remove
arm
too
cover
by
opening
stitch
chart,
re¬
moving
screw,
and
sliding
top
cover
toward
left
and
off
the
machine.
Remove
arm
top
cover
by
removing
the
two
screws
and
lifting
cover
from
machine.
Lay
machine
on
back,
loosen
screws
from
the
four
corners
of
the
machine-bed
cover,
and
remove
cover
from
underside
of
machine.
Wipe
out
any
oil
or
grease
accumulated
inside
arm-toD
and
bed
covers.
Oil
machine
as
indicated
below,
and
on
pages
3,
4
and
5
for
specific
class
of
machine.
Apply
one
drop
of
oil
between
the
casting
and
the
bobbin
push-button
release
lever.
CLASS
626
MACHINES:
This
class
of
machine,
supplied
only
for
use
with
the
standard
cam
stack,
does
not
require
the
access
means
provided
by
the
hinged
top
cover.
Ac¬
cordingly,
the
following
instructions
do
not
apply
to
Class
626
Machines.
Removal
Remove
top
cover
from
machine
as'described
on
page
3.
Remove
the
two
self-tapping
screws
on
underside
of
cover
holding
bracket
to
cover.
Remove
holding
ring
from
top
lid.
Remove
stitch
indicator
chart
from
lid.
Remove
self-tapping
screws
in
lid,
disengaging
hinge.
Replacement
Fasten
new
hinge
in
lid
with
self-tapping
screws.
Replace
stitch
indicator
in
top
lid
and
secure
it
with
the
holding
ring-
Replace
self-tapping
screws
through
bracket.
Do
NOT
tighten
securely.
Loosen
adjustment
screws
in
bracket.
Adjust
lid
so
that
it
is
flush
with
top
cover.
(This
is
done
by
raising
and
lowering
the
lid
on
the
slots
provided
in
the
bracket
while
the
adjustment
screws
are
loose,
and
by
adjusting
it
to
the
left
or
right
while
the
self-tapping
screws
are
loose
in
the
over-
sized
holes.)
When
lid
is
correctly
fitted,
tighten
the
self-tapoing
screws
and
the
adjustment
screws
in
the
bracket.
Replace
cover
and
secure
it
with
two
cover
screws.
THE
ROTATING
HOOK
VERTICAL
GEAR
Removal
CAUTION:
Hook-shaft
gears
and
hand-wheel
gea»
may
be
removed
to
facilitate
adjustments.
DO
NOT
DISTURB
THE
MESH
OF
ANY
OTHER
GEAR
IN
THIS
MACHINE.
All
other
gears
are
mated
and
cor¬
rectly
timed.
Replacements
should
be
made
only
at
the
factory.
Remove
needle,
presser
foot,
throat
plate,
bed
slide,
bobbin
case,
feed
dog,
cushion-spring
bracket,
and
position
finger.
Remove
bed
cover.
Remove
feed-1
iftinq
rock-shaft
and
feed
rock-
shaft
with
pull-off
finger
as
instructed
on
page
25,
Service
Manual
for
Classes
600
and
603
Machines.
Remove
actuating
lever
and
bobbin
driver
as
in¬
structed
on
page
9.
With
chalk
or
crayon,
mark
the
two
bevel
gears
as
illustrated.
(Mark
one
tooth
of
one
gear,
and
the
corresponding
space
for
that
tooth
in
the
other
gear.)
This
assures
proper
mesh
when
replacing.
Loosen
set
screw
in
vertical
bevel
gear,
and
re¬
move
gear
from
hook
shaft.
Lift
rotating
hook
assembly
from
machine.
Replacement
InstalI
rotating-hook
assembly
into
machine.
Using
the
guide
marks
previous
ly
made,
mesh
vertical
bevel
gear
with
horizontal
bevel
gear.
Turn
vertical
hook-
shaft
until
flat
side
of
shaft
is
under
set
screw
in
bevel
gear,
and
tighten
set
screw
securelv.
Replace
bobbin
driver
and
actuating
lever,
as
instructed
on
page
9.
Insert
pull-off
finger
into
machine
and
reoiace
feed
rock-shaft
and
feed-lifting
rock-shatt
as
in¬
structed
on
page
25,
Service
Manual
for
v-lasses
600
and
603
Machines
Check
and
adjust
hook
as
instructed
on
pages
7
and
3.
Replace
all
other
parts
previously
instructed
for
removal,
except
in
reverse
order.
6
To
Time
the
Hook
Sot
noodle
bar
at
correct
height,
and
time
the
needle-bar
vibrating
mechanism
as
instructed
on
pages
7
and
8,
Service
Manual
for
Classes
600
and
603
Machines.
Insert
a
Size
18
needle
up
into
the
needle
clamp.
Remove
throat
plate,
bed
slide,
bobbin
case,
and
bottom
cover.
It
is
not
necessary
to
remove
the
feed
dog
to
time
the
hook.
Adjust
machine
for
straight
stitching
in
center
needle
position.
Turn
hand
wheel
over
toward
operator
until
lower
timing
mark
is
aligned
with
lower
edge
of
needle-
bar
bushing
on
UPWARD
STROKE
of
needle
bar.
At
this
position,
point
of
hook
should
be
at
center
of
needle
as
illustrated.
To
adjust,
loosen
the
two
set
screws
in
horizontal
bevel
gear.
While
maintaining
position
of
needle
bar,
turn
vertical
bevel
gear
at
hook-end
of
shaft
until
point
of
hook
is
in
correct
position.
Then
tighten
the
two
bevel-gear
set
screws
securely,
making
cer¬
tain
that
gears
are
correctly
meshed
without
binding.
CAUTION:
Hub
of
horizontal
bevel
gear
should
not
contact
face
of
bushing.
Replace
throat
plate,
slide
plate,
bobbin
case,
and
bottom
cover.
VERTICAL
BEVEL
SETSCREWS
HCRIZONTAL
3
EV
EL
\
SEAR
GEAR
HUB
SHOULD
HOT
CONTACT
FACE
OF
BUSHING
7
To
Position
Hook
to
or
from
Needle
Set
needle
bar
at
correct
height,
and
time
the
hook
as
previously
instructed.
Turn
hand
wheel
until
point
of
hook
is
directly
behind
needle.
When
correctly
set,
the
distance
be¬
tween
the
needle
and
hook-point
should
be
approx¬
imately
0.004
inch,
as
illustrated.
HOOK
POINT
SETTING:
With
bobbin
push-button
in
winding
position,
remove
locator
nut
by
turning
in
a
CLOCK¬
WISE
direction.
Remove
bobbin
push-button
assembly
(see
instructions
on
poge
9),
and
remove
locator.
Careful
ly
mark
the
two
bevel
gears,
as
illustrated,
to
assure
proper
meshing
of
gears
when
replacing.
Then
loosen
set
screw
in
vertical
hook-shaft
bevel-
gear
and
remove
gear
from
shaft.
Loosen
set
screw
holding
the
eccentric
bushing.
Turn
the
eccentric
bushing
while
maintaining
posi¬
tion
of
hook,
until
correct
distance
between
needle
and
point
of
hook
is
attained.
Replace
bevel-gear
using
the
previously-made
guide
marks
to
assure
correct
meshing
of
gears.
Replace
all
other
parts
in
reverseorder
instructed
for
removal.
Set
winding
mechanism
as
instructed
on
page
9.
CAUTION:
Check
for
binding
or
end
play
in
hook
dri
ving-s
haft.
F
or
adjustment
and
removal,
see
page
24
of
Service
Manual
for
600
and
603
Machines,
and
page
6
of
this
supplement
for
removal
of
hook.
s
WINDING
MECHANISM
Bobbin
Push-Button
Assembly
Removal
and
Replacement
Open
slide
plate.
Place
push-button
irr
winding
position.
Lay
machine
on
back
and
remove
bed
cover
from
machine.
Remove
locator
nut
from
bobbin
driver
by
turning
in
a
CLOCKWISE
direction.
Then
remove
the
two
screws
fastening
the
push-button
assembly
to
the
underside
of
the
bed.
Slide
assembly
out
as
a
complete
unit,
being
careful
not
to
bend
the
push¬
button
release
lever.
To
replace,
follow
the
same
directions
as
for
removal,
except
in
reverse
order.
Bobbin
Driver
Removal
and
Replacement
Teen
slide
aiaTe.
Remove
‘hroat
plate,
bobbin
cose,
one
;ea
cover.
Per
stitch
enern
seiecrcr
ct
p
•r.'cnes
oer
nen,
one
-pm
non
a
-vneei
jnri:
eec
cog.
is
m
its
extreme
'ear
oosinon.
Remove
iocaror
nut,
pusn-button
assembly,
and
locator.
Then
slide
bobbin
driver
up,
rotate
until
apron
is
opposite
feed
dog,
and
lift
out
of
machine.
To
replace,
install
bobbin
driver
in
machine,
ro¬
tating
it
until
it
seats
firmly
into
place.
Then
replace
locator,
push-button
assembly,
locator
nut,
throat
piate,
and
bobbin
case.
Adjustment
To
adjust
the
height
of
the
bobbin
driver,
place
push-button
in
winding
position
and
loosen
adjustable
extension
screw
at
end
of
lifting
bracket.
Press
up¬
ward
on
bracket
until
bobbin
rises
slightly
above
top
of
bobbin
case.
Then
release
upward
pressure
slight¬
ly,
allowing
bobbin
to
seat
correctly
into
bobbin
case.
Without
disturbing
this
setting,
tighten
ex¬
tension
screw
securely
9
NEEDLE-THREAD
TENSION
ASSEMBLY
STUD
CHECK
SPRING
RELEASING
PIN
SET
SCREW
THREAD
GUARD
Removal
and
Disassembly
Open
face
plate,
loosen
stud
set-screw
and
re¬
move
entire
tension
assembly,
as
illustrated.
Loosen
set
screw
in
dial
and
remove
dial.
Turn
adaptor
to
left
until
it
is
free
from
the
stud.
Remove
indicator
stop,
spring,
cup,
and
tension
releasing-pin.
The
check
spring,
tension
discs,
and
thread
guard
should
be
removea
from
‘he
stud
as
a
unit.
Reassemoiv
and
Rsoiacement
Replace
releasing-pm
in
stud.
Place
tension
discs
on
the
thread
guard,
align
coil
of
check
spring
with
holes
in
tension
discs
and
thread
guard,
and
place
assembly
on
stud
with
tail
of
check
spring
entering
top
groove
of
sprocket
on
stud.
Replace
cup,
spring,
indicator
stop
(with
tab
at
bottom
position),
and
adaptor.
Replace
dial,
making
certain
that
stop
on
inside
of
dial
is
in
contact
with
left
side
of
in¬
dicator-stop
tab
when
dial
is
set
at
zero
(0)
tension.
Tiahten
set
screw
and
place
entire
assembly
onto
machine,
with
check
spring
resting
on
the
top
sur¬
face
of
the
check-spring
stop.
Adjustments
For
adjustments
of
the
needle-thread
tension,
check-spring
stroke,
check-spring
tension,
and
bob-
bin-case
latch
tension,
refer
to
pages
21
and
22
in
the
Service
Manual
for
C!asses600
and
603
Machines.
10
THROAT-PLATE
POSITION
BRACKET
y
Removal
and
Replacement
Remove
throat
plate,
and
set
throat-plate
posi¬
tion
lever
in
REGULAR
position.
Press
left
end
of
position
bracket
toward
underside
of
machine
bed
as
far
as
possible,
and
remove
adjusting
screw.
Swing
left
end
of
bracket
away
from
machine
bed
and
remove
the
two
throat-plate
clamps
with
brackets,
pins,
and
springs.
Set
position
lever
in
DARN
posi¬
tion
and
remove
screws
from
indicator
plate.
Lift
indicator
plate,
stop
plate,
and
stpp-plate
spring
from
machine
bed,
and
remove
position
bracket
from
underside
of
machine.
Replace
throat
plate
position
bracket
in
reverse
order
of
its
removal,
but
observe
the
following:
Stop
plate
spring
should
be
replaced
with
the
curved
portions
of
spring
under
cross-piece
of
lever.
Remainder
of
spring
should
extend
toward
left.
Position
bracket
must
be
inserted
in
grooves
under
machine
bed.
Adjusting
screw
should
be
turned
in
flush
with
bottom
of
casting
while
pressing
left
end
of
bracket
toward
underside
of
bed.
RemovaI
Remove
top
cover.
Remove
tension
stud.
Remove
two
screws
holding
front
stop,
and
selec¬
tor
mechanism
assembly.
Remove
the
front
stop.
Disengage
tension-arm
spring
from
selector
mech¬
anism.
Remove
selector
mechanism
assembly.
Replacement
Replace
selector
mechanism
assembly
in
the
machine,
fastening
it
in
place
with
the
left
screw.
Place
the
front
stop
on
top
of
the
mounting
brack¬
et,
and
fasten
it
with
the
right
screw.
Place
tension
arm
over
stud
hole,
being
sure
that
the
arm
is
behind
the
arm
plate.
In
sert
tens
ion
stud.
Loosen
the
left
and
right
screws
(which
were
tightened
previously
on
selector
assembly
and
front
stop),
and
set
the
bracket
parallel
with
the
cross
shaft
until
the
right
edge
of
the
bracket
is
approxi¬
mately
L
16”
to
3/32”
from
the
cast
boss
for
the
cross-shaft
bearing.
Then
re-tignten
screws.
Engage
driving
spring,
being
sure
that
tail
of
spring
is
up
when
put
into
place
on
release
lever.
Again,
loosen
right
screw
of
mounting
bracket
and
set
stop
to
limit
travel
of
selector
arm
(This
is
done
to
prevent
disengagement
of
the
selector
arm
and
the
follower,
and
yet
give
free
movement
to
the
selector
arm
when
selecting
patterns.)
Replace
top
cover.
12
THE
RELEASE
MECHANISM
(Cont'd)
Adjustments
Setting
the
Release
Mechanism
Remove
arm
top
cover.
Be
sure
stitch
pattern
selectors
are
properly
en¬
gaged.
Otherwise,
machine
will
not
engage
when
in
operation.
If
machine
does
not
engage
after
selectors
are
engaged,
the
releasing
mechanism
requires
ad¬
justment
as
follows:
Loosen
bracket
screw
in
adjustable
bracket
and
engage
release
mechanism
by
swinging
the
bracket
to
the
right
by
hand
until
it
engages.
Tighten
screw.
Front
Stop
and
Selector
Mechanism
Assembly
REAR
RETURN
SPRING
FRONT
RETURN
SPRING
E3
jmm
rear
stop
BUSHING
(SPLIT)
M3
FRONT
RETURN
SPRING
CAM
SELECTOR
ARM
SHAFT
FOR
626
MACHINE
Loosen
screw
on
adjustable
lever
ana
move
the
lever
until
it
mcKes
contact
with
the
plastic
sieeves.
—
.rn
-ana
.vheei
to
ns
are
enaacsment
or
•eieasmc
ever.
Rs-
r
:
a
n
t
sn
screw
sec’jrsiv.
Setting
the
Loading
Cam
The
Loading
Cam
should
be
pre-set
to
within
1/32
to
1/16
inch
from
cross-shaft
boss,
as
shown.
13
CAM
STACK
SPRING
SCREW
STUD
CAM
STACK
CLASS
626
MACHIN
ES:
This
class
of
machine
is
designed
for
use
only
with
the
factory-installed
standard
cam
stack,
and
is
provided
only
with
a
Front
Cam
Selector
Arm.
Ac¬
cordingly,
removal
and
replacement
of
cams
in
this
ma¬
chine
should
be
performed
only
by
authorized
servicemen
during
regular
maintenance
periods,
and
those
instructions
referring
to
Rear
Com
Selector
Arm
do
not
apply
to
Class
626
Machines.
CLASS
628
MACHINES:
This
class
of
machine
is
designed
for
use
only
with
one
replaceable
Fashion
Disc
stitch-
pattern
cam
during
any
one
sewing
operation,
and
is
pro¬
vided
only
with
a
Front
Cam
Follower.
Accordingly,
those
instructions
referring
to
Cam
Stack
Removal
and
Replace¬
ment,
Adjustments,
and
Stops
do
not
apply
to
Class
628
Mach
ines.
Removal
and
Replacement
Set
stitch
pattern
selector
at
“A
—
K”.
Remove
arm
top
cover
and
removable
Fashion
Disc
fstitch-oattern
cam).
Remove
large
screw-stud
with
its
spring.
Remove
cam
stack.
Replace
cam
stack,
meshing
worm
wheel
of
cam
stack
with
worm
of
arm
shaft.
Reolace
screw-stua
with
its
SDring.
Replace
Fashion
Disc
ana
arm
rop
cover.
Aai
u
srmenrs
i
iming
the
Cam
Stack
Remove
arm
top
cover
and
Fashion
Disc,
and
large
screw-stud
with
its
spring.
Using
stitch-pattern
selector,
bring
rear
follower
in
contact
with
edge
of
top
cam
of
cam
stack.
Turn
hand
wheel
over
toward
operator
until
timing
mark
is
at
point
of
contact
with
rear
follower,
as
shown.
At
this
setting,
the
needle
bar
should
be
at
its
lowest
position.
Loosen
each
of
the
three
clamping
screws
on
top
of
cam
stack.
While
holding
needle
bar
at
its
lowest
position,,
manually
rotate
entire
cam
stack
clockwise
until
timing
mark
reaches
point
of
contact
with
rear
follow¬
er,
as
shown.
Tighten
the
three
clamping
screws.
Replace
stud
with
its
spring.
Tighten
stud.
Replace
Fashion
Disc
and
arm
top
cover.
14
THE
CAM
STACK
(Cont’d)
Removal
and
Replacement
Remove
arm
top
cover
and
control
panel.
Remove
cam
stack
as
previously
instructed
on
page
14.
Loosen
the
clamping
screw
in
lower
selector
arm
by
inserting
screwdriver
through
hole
in
upper
arm.
Remove
locating
screw
from
plastic
cam.
Remove
the
screw
in
rear
follower
arm.
Loosen
the
rear-stop-bushing
set-screw.
Withdraw
selector-arm
shaft
from
rear
of
machine
arm,
releasing
front
selector-arm
and
return-spring,
plastic
cam,
spring,
rear
selector-arm,
and
rear
se¬
lector-arm
return-spring.
Remove
selector
arms
from
machine.
Remove
two
followers
from
index
pins.
Replace
two
followers,
and
replace
selector
arms
with
cam
and
return-springs
in
position,
making
cer¬
tain
that
hinged
brackets
fit
into
slots
in
followers.
Replace
selector-arm
shaft
through
follower
arms.
Replace
rear
follower-arm
screw
making
certain
that
it
clamps
down
on
flat
part
of
shaft.
Tighten
rear-stop-bushing
set-screw
securely.
Tighten
the
damning
screw
in
lower
selector-arm.
Rsdiccs
ram
stack.
Cneck
one
aajust
the
release
mechcmsm
as
;
n
-
Aa
i
u
stmen
r
s
Setting
the
Index
Pins
Set
stitch
selectors
at
“J”
and
"R”.
Remove
arm
top
cover
and
control
panel.
At
this
setting,
top
surface
of
two
arm
followers
should
be
approximately
1/64
inch
below
top
surface
of
c
am
stack.
NOTE:
Position
of
two
arm
followers
is
determined
by
height
or
index
pins.
Loosen
rear
index-pin
set-screw.
Raise
or
lower
rear
index-pin
as
required,
to
bring
top
surface
of
rear
follower
1/64
inch
below
top
sur¬
face
of
cam
stack,
then
tighten
set
screw
securely.
Loosen
front
index-pin
set-screw
at
front
of
ma¬
chine
arm.
Raise
or
lower
front
index-pin
as
required,
then
tighten
set
screw
securely.
15
CAM
STACK
(Cont’d.)
Setting
Cam-Selector-Arm
Stops
Remove
arm
top
cover.
Check
adjustment
of
worm
wheel
shaft
(see
in¬
struction
on
page
17).
Set
selector
at
“D"
and
“L
1
*
.
Turn
hand
wheel
over
toward
operator
until
arm-
bracket
followers
rest
upon
high
points
of
bottom
(zigzag)
cam
of
cam
stack.
At
this
setting,
when
stitch
pattern
selectors
are
depressed
as
far
as
possible,
clearance
between
both
followers
and
high
point
of
bottom
cam
should
be
0.010
and
0.012
inch.
Front
Selector-Arm
Stop
Disengage
release
mechanism
by
pushing
in
on
upper
selector
button.
Loosen
screw
in
front
selector-arm
stop
and
de¬
press
top
selector
button
until
there
is
approximately
0.010
inch
clearance
between
front
follower
and
cam.
Maintain
this
clearance
while
moving
stop
toward
front
of
machine
until
it
makes
contact
with
front
selector-arm.
Then
tighten
screw
securely.
Rear
Selector
Arm
Stop
Loosen
stop-bushing
set-screw
at
rear
of
cam-
selector
arm-shaft.
?-ess
lower
selector
button
until
there
is
ccDroximateiv
0.010
inch
clearance
between
■
e
ar
'
0
!
lower
one
ram.
rlcintcin
this
set-
ng
vn:
!e
moving
stoo
ousning
•award
'"rant
at
macrvne
_nr;
t
maxes
contact
witn
rear
-
o
l
.ewer-arm,
men
rignten
set
screw
securely.
Aligning
Indicator
with
Selector
Letters
Indicators
“A”
to
“J”
Loosen
set
screw
through
hole
in
upper
selector
arm.
Align
indicator
mark
with
“A”
position
on
front
panel,
making
sure
that
rear
follower
is
in
contact
with
aluminum
bight-control
ring
(lowest
ring
with
largest
diameter
under
the
cam
stack).
Tighten
set
screw
securely.
Indicator
“K”
to
“Special”
Loosen
hex
head
screw
in
front
follower
arm.
Align
indicator
mark
with
”K”
position
on
front
panel,
making
sure
that
front
follower
is
in
contact
with
aluminum
bight-control
ring
(third
ring
from
bot¬
tom
under
the
cam
stack).
Then
tighten
hex
head
screw
CAM
STACK
(Cont’d.)
Cam-Selector-Arm
Shaft
Return-Spring
Removal
and
Replacement
CLASS
620,
625
and
628
MACHINES:
To
remove
front
selector-arm
return-spring,
follow
procedure
described
above
for
removal
of
cam-selec¬
tor-arm
shaft
down
to
withdrawal
of
shaft
from
rear
of
machine.
As
shaft
is
withdrawn,
the
tension-type
return¬
spring
can
be
lifted
from
between
front
and
rear
disc-
selector-arm
brackets.
To
replace,
insert
new
return-spring
between
front
and
rear
disc-selector-arm
brackets,
slide
shaft
for¬
ward
to
engage
spring,
and
reassemble
cam-selector-
arm
shaft
and
follower
as
described.
To
remove
rear
selector-arm
return-spring,
follow
procedure
described
above
for
removal
of
cam-seiee-
tor-arm
shaft
down
to
removal
of
selector
arms
from
machine.
This
procedure
releases
coil-type
rear
re¬
turn-spring.
To
replace,
fit
new
return-spring
on
shaft
and
reassemble
cam-selector-arm
shaft
and
followers
as
described
above.
Check
ana
adiust
*he
-eiecse
mechanism
as
de¬
ar
cec
on
cage
'4.
CLASS
626
MACHINES
To
remove
selector-arm
return-spring,
follow
pro¬
cedure
described
above
for
removal
of
cam-selector-
arm
shaft
down
to
withdrawal
of
shaft
from
rear
of
machine,
As
shaft
is
withdrawn,
the
tension-type
return
soring
can
be
lifted
from
the
shaft
between
the
legs
of
the
selector-arm
bracket.
To
replace,
fit
new
return-spring
on
shaft
and
reassemble
cam-selector-arm
shaft
and
follower
as
described
above,
Check
and
adjust
the
release
mechanism
as
in¬
structed
on
page
14.
PRONT
RETURN
SPRING
620,
625
:na
623
Mac
nines
REAR
STOP
BUSHING
(SPLIT)
626
Machines
17
NOTE:
The
following
instructions
apply
goneraily'to
Class
620,
625,
626
and
628
Machines.
As
indicated
on
page
13,
however.
Class
628
Machines
must
use
the
Sight-Amplitude
Selector
in
lieu
of
a
Release
Mechanism
in
order
to
neu¬
tralize
the
particular
zig-zag
stitch
pattern
provided
by
the
replaceable
Fashion
Disc
utilized.
Accordingly,
the
section
on
page
20
dealing
with
Bight-Amplitude
Adjust¬
ments
will
be
particularly
applicable
to
users
of
Class
628
Machines.
Removal
and
Replacement
Remove
arm
top
cover,
face
plate,
and
control
panel.
Set
stitch-pattern
selectors
at
“A”
—
“K”.
Remove
driving-arm
spring.
Remove
bight-lever
screw
from
bracket,
and
re¬
move
bight
lever.
Loosen
bight-amplitude
set-screw
and
remove
entire
cam
stack
assembly.
Remove
bight-amplitude
and
pattern
selector.
Replace
pattern
selector
in
the
reverse
order
of
its
removal.
Observe
the
following:
Assemble
cam
stack
as
a
complete
unit.
Upper
eccentric
half
of
worm
wheel
shaft
should
be
turned
toward
hand-wheel-end
of
machine,
as
shown.
Make
certain
that
driving-arm
ball-pivot
is
en¬
gaged
with
pattern
selector.
Set
mesh
between
worm
of
arm
shaft
and
worm
wheel
of
pattern-selector
by
turning
bight-amplitude
shaft
clockwise
so
that
there
is
no
binding
and
a
minimum
amount
of
backlash.
Tighten
bight-amplitude
set
screw.
Replace
driving-arm
spring
Replace
bight
lever
and
fasten
with
set
screw.
Adjust
machine
as
instructed
below
and
on
fol¬
lowing
page.
18
Adjustments
Setting
the
Bight-Amplitude
Stop-Plates
Set
index
pins
at
correct
height
and
time
the
cam
stack.
CHECK:
(At
No.
1
Position)
With
stitch
controls
set
at
"A
—
L
—
3”,
operate
machine
at
slow
speed
and,
at
same
time,
move
stitch
width
(bight)
lever
to
No.
1
position.
Movement
of
driving
arm
and
vibrating
bracket
should
stop
at
same
time
that
movement
of
bight
lever
stops
at
No.
1
posi¬
tion.
Loosen
clamping
screw
in
left
stop-plate.
Move
bight
lever
to
No.
3
position.
Run
machine
at
moderate
speed
and
move
bight
lever
toward
left,
to
point
where
there
is
no
movement
of
vibrating
bracket
or
driving
arm.
DO
NOT
PASS
THIS
POINT.
Maintain
this
position
of
bight
lever,
and
move
left
stop-plate
forward
(toward
operator)
against
bight-amplitude
bracket
beneath
cam
stack.
Hold
stop-plate
at
this
setting
and
tighten
clamp¬
ing
screw
securely.
CHECK:
At
Mo.
5
Position:
sf.tcn-widtn
bignt.
.ever
to
.No.
5
position.
Move¬
ment
of
arivmg
arm
and
vibrating
bracket
should
stop
at
same
time
that
movement
of
bight
lever
stops
at
No.
5
position.
Loosen
clamping
screw
in
right
stop-plate.
Move
bight
lever
to
No.
3
position.
Run
machine
at
moderate
speed
and
move
bignt
lever
toward
right
to
point
where
there
is
no
move¬
ment
of
vibrating
bracket
or
driving
arm.
DO
NOT
PASS
THIS
POINT.
Maintain
this
position
of
bight
lever
and
move
right
stop-plate
forward
(toward
operator)
against
bight-amplitude
bracket
beneath
cam
stack.
Hold
stop
plate
at
this
setting
and
tighten
clamp¬
ing
screw
securely.
19
Other manuals for 620
1
This manual suits for next models
3
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