Knives - Baby Lock BL4-428 Instruction Booklet

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7
KNIVES
Two
blades located at the right
of
the
needle
plate trim
the fabric
edge
just
ahead
of
the stitching.
Unlike household
knives,
they
are
approximately
1116" (1.5mm)
thick
and pose no danger in handl-
ing. Their cutting power
is derived
not from
sharpness,
but from
the
angle
of the precision-ground
edges.
Make
sure
you
are alwayes sewing
with
clean, sharp
knife
blades. The feeding action
of
the machine
is
dependent
on the
knives being
in
good
condition.
Never sew over
pins
with
your
serger. Doing
so
would
damage
both
blades and make replacement necessary.
The upper knife
is
made
of
an
especially hard steel and should remain sharp
for
a
long time,
probably
many years. The lower knife is
made
of
a softer
steel and
will
require
periodic
replacement. The
frequency
of
replacement is determined
by how often you
sew,
how
clean
you
keep
your
serger and
the types
of fabric you
sew.
Synthetic, metallic and hard-finish fibers
cause more wear
to
the knife
blades than do softer natural fibers.
Upper
Needle
plate
knife
Lower
knife
Figure 19
When
you
notice the
fabric
not feeding
readily or the
edges
of
the
fabric
not cleanly
cut,
replace
the lower knife (See page 38).
The upper knife
can be moved
out
of cutting
position
when
trimming
is
not
required.
The lower knife
is
in
a
fixed position
and remains
that way.
even
when
cutting
is
not
desired.
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