Even when stitching delicate
fabr
ics, the machine must
produce
a seam which
does
not pucker.
All
of
the
above
tests, naturally, should
be
repeated
with
narrow
and
wide zigzag stitches. Also try
out
whether the machine works pro-
perly
when you overcast
an
edge,
and
check
to
see
that
it
does
not
skip stitches
when
the needle stitches
over
the
edge.
After switching back
to
straight stitching, check the performance
of
the
machine
with different needle positions.
Checking the Automatic Mechanism
If
the machine
in
question
is
equipped
with
an
automatic embroidery mecha-
nism (Pfaff
260-261
and
Pfaff 360-261), stitch various embroidery designs
to
check
the
performance
of
this mechanism. For best results, choose the follow-
ing settings:
D
3-
C
2-
B left - E 1
D
7-
C
3-
B
left-
E 1
D 4 - C
5-
B
left-
E 1
Run
the machine slowly
and
check whether the automatic embroidery mecha-
nism works properly
as
it
gradually
changes the stitch width from 0
to
4,
and
bock to 0
again.
The mechanism must not
get
stuck
in
the process,
nor
should
the
thread
break.
Before
an
Automatic is delivered
to
the
customer, it should
be
oiled thoroughly.
Do
not forget
to
put
a few
drops
of
oil
on
the oil
pad
which serves to provide
a constant
oil
film
on
the rims
of
the
individual pattern cams.
Regulating the Pressure
on
the
Material
The medium amount
of
pressure
for
which the presser
bar
has
been
set
at
the
factory
will
be
found
adequate
for
all
ordinary
sewing
operations
and
need
not
be
changed. If mostly sheer
and
delicate fabrics
are
to
be
sewn, however,
ease
the pressure exerted by
the
presser
bar
spring by turning
out
regulating
screw
V (Fig.
75).
To
increase the pressure
for
dense
and
thick materials, turn
screw
V inwardly.
Observe
these
general
rules:
Normal
pressure:
light
pressure:
Strong pressure:
Regulating screw
is
flush with
top
of
casting.
Regulating screw protrudes
about
'/s'
from
top
of
casting.
Do
not
turn
the
screw
out
too
far
as,
otherwise, it will
bear
against
the
top
cover.
Regulating screw is
about
3
h6• below
top
of
casting.
43
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