- 21 -
2-thread overcast chain stitch (overlock)
Figure 53 shows you the stitch pattern for this stitch.
This stitch with a needle and 2 threads is used for tidying the edges of
light or stretchy fabrics. By changing the needle position you can obtain a
narrow or a wide overcast seam.
Adjust the thread tension selectors
r t z u
to the appropriate values
(see table) then sew a test seam on the material being used.
For this type of stitch insert the upper looper element in the upper looper
o
.
Should the lower looper yarn appear to be too tight or the needle thread
too loose (Fig. 54) :
• turn the thread tension selector for the lower looper thread
u
(yellow)
to a lower number, or ...
• turn the thread tension selector for the needle (blue
r
or green
t
) to
a higher number.
Should the lower looper yarn appear to be too loose (Fig. 55), turn the
thread tension selector for the lower looper thread
u
(yellow) to a higher
number.
Needle position
Seam width switch
S
Stitch length
2 - 4
Upper looper element
insert
Textiles
Tensioning the thread
blue
green
red
yellow
light
material
2.0
-
Inserting the
upper looper
element
0
medium-
weight
material
2.5
-
Inserting the
upper looper
element
0
heavy
material
3.5
-
Inserting the
upper looper
element
0.5
Textiles
Tensioning the thread
blue
green
red
yellow
light material
-
1.5
Inserting the
upper looper
element
0.5
medium-
weight
material
-
1.5
Inserting the
upper looper
element
0.5
heavy
material
-
3.0
Inserting the
upper looper
element
1.5
Top
Underside
Correct thread tension
Incorrect thread tension
Incorrect thread tension
needle thread
Top
Underside
needle thread
lower looper thread
Top
Underside
needle thread
lower looper thread
lower looper thread
Fig. 53
Fig. 54
Fig. 55
