SYNCHRONIZING LOOPER AND NEEDLE
MOTIONS
Looper
dri
ve
belt
(A,
Fig.
6)
has
proper tension
if,
when
turning
handwheel
in operating
direction to position looper in the center of
its
(right
to
left)
travel -there
is
no
noticable
(right
to
left)
play
in
the looper
mechanism.
There
should
be
approximately 1/8 inch
(3.2mm)
deflection in looper drive
belt
when
pressing firmly with
thumb,
midway
between
sprockets (Band
C).
Adjustment
can
be
made
by
loosening
two
screws
(D)
and
turn looper
module
(E)
clockwise (as
viewed
from
handwheel
end
of
machine)
to tighten
belt
tension or counterclockwise to loosen
belt
tension.
It
is
easier
to turn looper
module
by
turning
cast-off
plate
mounting
bracket (F).
At
this
time, notch
{G)
on
end
of looper
module
should
be
facing mostly
in
the
upward
position
(between
9
and
3 o'clock).
Loosen
binder
screw
(H)
and
reposition
cast-off
plate
mounting
bracket
(F)
so
its
leading
edge
(J)
is
vertical to
and
parallel with
bed
casting.
Ret
ighten
screw
(H)
assurin9
that
right
side of
mounting
bracket
is
flush with
right
side of looper
module.
Tighten
screws
(OJ.
Turn
handwheel
in operating direction until point of looper,
moving
to the
left,
is
even
with
the
left
side of needle.
Note
the height
of
the
eye
of the needle with respect to the looper point;
now
turn
handwheel
in the reverse direction until point of looper, again
moving
to the
left,
is
even
with the
left
side of needle.
If
the height of the
eye
of the needle with respect to the looper
point are the
same,
looper
and
needle
motions
are synchronized- a variation of
.005
inch
(.127mm)
is
allowable.
If
machine
is
out of synchronization, proceed
as
follows :
Remove
right cloth
plate
covering the dry
chamber
.
Remove
presser foot, throat
plate,
feed
dog
and
looper.
Using
gauge
No.
21227
R,
place
gauge
plate
on
throat plate seat using throat plate
screws
for attaching.
With
looper holder
at
EXTREME
right
end
of
travel,
insert
pin (included with
gauge)
into looper holder.
Insert
shank
of indicator
gauge
into the hole
used
for needle thread take-up wire.
Turn
hand-
wheel
in
operating direction until pin
makes
contact with
edge
of
gauge
plate. Set the height
of
gauge
so
left
end
of pointer
rests
on
top of needle bar
and
right
end
of pointer aligns with "0",
lock
shank
of
gauge
in
this
position with
set
screw
used
for needle thread take-up wire.
Turn
hand-
wheel
in reverse direction until pin in looper holder again
makes
contact with
edge
of
gauge
plate,
note the reading
on
gauge.
Avariation of
one
graduation
on
the scale
is
permissable.
If
the reading
is
above
"0"
on
the gauge, 1
oosen
screws
(
K,
Fig,
6)
and
advance
1ooper drive
rear sprocket
(B)
(towards the operator);
if
the reading
is
below
"0"
on
the gauge, sprocket
(B)
should
be
retarded
slightly
(away
from
operator).
If
the variation
on
the scale of the
gauge
is
to
the
EXTREME
- a
STARTING
POINT
for adjustment
would
be
to position sprocket
(B)
so
that
when
needle
bar
is
at
bottom
of
its
stroke, the looper
is
at
right
end
of
its
travel.
To
obtain the
above
condition, loosen
screws
(K)
and
turn sprocket
{B)
so
that
looper
is
at
the
right
end
of
it
s
travel.
While
holding looper
shaft,
turn
handwheel
to bring needle bar to
bottom
of
its
stroke
and
s
nug
screws
(K).
Then
proceed to fine adjustment
as
required to
attain
"0"
plus or
minus
1
on
the
gauge
in
both
directions
and
tighten
screws
(K)
securely, assuring
belt
is
centered
on
sprockets.
Fig.
6
If
a synchronizing
gauge
is
not available -
and
the distance
from
the
eye
of the needle to the
bottom
side of the looper
was
greater
when
the
handwheel
was
turned in the operating direction, adjust s
am
e as
if
reading
wa
s
above
"0"
on
the
gauge
-reverse th
is
ad-
justment
if
distance
from
the
eye
of the needle to the
bottom
side of the looper
was
less.
Replace
all
parts
that
were
re
moved
for
this
adjustment.
8
From the library of: Superior Sewing Machine & Supply LLC
