2-Thread Overcast Chain Stitch (Overlock) - Silvercrest SON 90 A1 Operating Instructions Manual

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.
Textiles
blue
light
2.0
material
medium-
2.5
weight
material
heavy
3.5
material
Textiles
blue
-
light material
medium-
-
weight
material
heavy
-
material
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.
Tensioning the thread
green red yellow
Inserting the
-
upper looper
element
Inserting the
-
upper looper
element
Inserting the
- 0.5
upper looper
element
Tensioning the thread
green red yellow
Inserting the
1.5 0.5
upper looper
element
Inserting the
1.5 0.5
upper looper
element
Inserting the
3.0 1.5
upper looper
element
Needle position
Seam width switch
Stitch length
Upper looper element
0
0
needle thread
Top
needle thread
Top
needle thread
Top
- 21 -
2 - 4
insert
Correct thread tension
Underside
Incorrect thread tension
lower looper thread
Underside
Incorrect thread tension
lower looper thread
Underside
S
lower looper thread
Fig. 53
Fig. 54
Fig. 55