- 25 -
3-thread overcast chain stitch (overlock)
Figure 67 shows you the stitch pattern for this stitch.
This stitch with a needle and 3 threads is used for sewing, for example,
decorative edges.
By changing the needle position you can obtain a narrow or a wide overcast
chain 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.
Should the upper looper yarn be too loose (Fig. 68):
• turn the thread tension selector for the upper looper thread
z
(red) to a
higher number.
Should the lower looper yarn be too loose (Fig. 69):
• turn the thread tension selector for the lower looper thread
u
(yellow)
to a higher number, or ...
• turn the thread tension selector for the upper looper thread
z
(red) to a
lower number.
Should the needle yarn be too loose (Fig. 70):
• turn the thread tension selector for the needle (blue
r
or green
t
) to a
higher number.
• turn the thread tension selector for the upper looper thread
z
(red) to a
lower number.
Textiles
Tensioning the thread
blue
green
red
yellow
light
material
2.0
-
0
4.0
medium-
weight
material
3.0
-
0.5
6.5
heavy
material
4.0
-
0.5
7.5
Textiles
Tensioning the thread
blue
green
red
yellow
light
material
-
1.5
0
5.0
medium-
weight
material
-
2.5
1.0
7.0
heavy
material
-
3.0
1.5
8.0
Needle position
Seam width switch
S
Stitch length
2 - 4
Upper looper element
not necessary
Correct thread tension
Top
Underside
Incorrect thread tension
needle thread
lower looper thread
upper looper thread
needle thread
Top
Underside
needle thread
lower looper thread
upper looper thread
needle thread
Top
Underside
needle thread
lower looper thread
upper looper thread
needle thread
Fig. 68
Fig. 69
Fig. 70
Top
Underside
needle thread
lower looper thread
upper looper thread
needle thread
Fig. 67
