QUESTION
Skipped
stitches are prone to occur when sewing
wads waterproofed by urethane treatment
in the sewing of such things as sportswear.
What is the remedy?
*
Cause
In
this case, the cause of the skipped stitches
is as follows. As shown in Figure 1, when
the cloth has been set and the sewing
begins, a polyurethane film sticks to
the surface, causing bad penetration.
As shown in Figure 2, the cloth ends up
entering the needle hole in the throat
plate, preventing a loop from being formed
in the needle thread.
Remedy
: JUKI Corporation
1.
Needle to be used: Use a needle with as
fine a count as possible. Use a ‘slim
point’ needle or a synthetic fibre super-needle
for preventing sticking to the needle
point.
*
Examples:
DB
x 1S #A : For a lockstitch machine; DB
x 1KN #A : For a lockstitch machine; DB
x 1SF #A : For a lockstitch machine; DC
x 27SF #A : For serge
2.
Throat plate: Use a small diameter needle
hole in the throat plate.
*
Examples:
Product
number 110-28008 (1.9mm) :
For
a standard lockstitch machine
Product
number 110-74002 (1.6mm) :
For
a thin fabric lockstitch machine
Product
number D1109555D0W (1.3mm) :
For
a thin fabric lockstitch machine
3.
Hook timing
Lower
the needle bar 0.2 to 0.5 mm and in that
state adjust the hook timing versus the
standard timing (according to timing lines
on the needle bars) to increase the needle
thread loop. Then, adjust the gap between
the needle and the hock blade point so
that it is as small as possible.
QUESTION
Thread
breakage is prone to occur during continuous
reverse sewing (Figure 1) and concealed
stitching (Figure 2) with fine-yarn count
synthetic thread (#60 and #80), on a 1-needle
lockstitch machine with an automatic thread
trimmer. What is the remedy?
*
Cause
In
the case of reverse sewing and concealed
stitching, thread slipping out from the
horn section of the inside hook retainer
for the hook tends to produce sagging
and jumbling, adversely affecting the
formation of the needle thread loop and
causing breakage of the thread.
Remedy
: JUKI Corporation
1.
Thread take-up spring
Increase
the standard 7 to 8 mm stroke to 10 to
12 mm. The lower thread tension changes
due to the upper thread tension, adjusting
it to a very weak condition (10~15 g).
Use a spring for thin fabric.
2.
Needle installation angle
From
the present condition, turn the needle
just a little to the left.
Note
: Be careful, as turning the needle too
far will lead to
skipped stitches.
3.
Needle bar thread guide
Use
product No. 110-35409 (type T). |
 |
4.
Arm thread guide B (area mounting)
Use
product No. 113-80508. |
 |
*Of
these four methods, the most effective
are 1 and 3. When installing it, we recommend
that you investigate it from methods 1 and 3.
