2
TABLE OF CONTENTS
Subject
Pages
Introduction
. . . . . . . . . . . . . . . . . 2
301
Stitch
Theory . . . . . . . . . . . . . . 7
Other Methods
of
Forming the
301
Stitch 17
Adjustments . . . . . . . . . 19
Technical Data . . . . . . . . . . . . . . 30
Skipped & I m proper Stitches . . . . . . 35
Needle Positioners & Thread Trimmers 37
Other
300
Class
Stitch
Types . . . . . . 38
INTRODUCTION
The
300
stitch
class
includes stitch types
that
interlock
a needle thread
with
a bobbin thread
by
the
use
of
a hook
or
shuttle mechanism.
Because
these threads
are
interlocked rather than interlooped, the
300
stitch
class
is
better
known
as
the LOCKSTITCH
class
of
stitches.
The most
popular stitch
formation
in the
300
stitch
class
is
the 301 stitch which
is
often referred
to
as
a
"plain
stitch",
"straight
stitch",
or
plain
"lockstitch".
Almost
half
of
all industrial sewing machines
in
use
today
produce stitch
type
301 which
is
the most popular stitch
used
in the industry. Some
reasons
for
this widespread
use
would
include:
the stitch
is
reversible and looks the
same
on both sides;
it
is
the tightest stitch
formation
which minimizes
seam
grinning;
it
consumes the least
amount
of
thread in its
formation;
it
has
a better
"hand",
or
feels smoother
to
the
touch;
lockstitch machines usually
have
a lower
initial
investment than machines
producing
other
stitches;
lockstitch machines
are
very versatile and
can
be
used
on a variety
of
operations.
The basic concept
of
carrying a needle loop around a bobbin may
seem
very simple,
but
when
you
consider:
that
the
rotary
hook
used
to
interlock
the threads rotates
at
speeds
up
to
12,000 revolutions per minute;
that
approximately
3"\6
inches
or
8.9 cm
of
needle thread
is
carried
below the material and around the bobbin during the
formation
of
each
stitch,
even
though
only
one stitch length
of
thread
is
consumed;
that
the stitch must appear the
same
on
both
sides
of
the
seam
which
sometimes
is
only
.020
of
an
inch
thick
...
You
may begin
to
question
how
simple the
formation
of
the 301 stitch really
is:
©Copyright
1980
UNION SPECIAL
CORPORATION-
Printed in U.S.A.
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