Checking Of The Knife Unit - JUKI DDL-9000C-S Instruction Manual

7-3-3. Checking of the knife unit

WARNING :
Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the
sewing machine.
❶
Standby state of the knife
A
S type : 5.5 to 6.5 mm
H type : 5.0 to 6.0 mm
❶
❶
Aligning state of salient portion of loop spreading
knife and thread trimming knife
Far end of the hole in
loop spreading knife
❶ aligns with the tip of
thread trimming knife ❷
❶
2.5 to 3 mm
State of engagement of knife
❷
❷
❷
❶
❷
A
❷
A
– 71 –
1) Check to make sure that the power switch is in
the OFF state. Remove the gauge (presser foot,
throat plate and feed dog) from around the needle.
2) In the standby state of loop spreading knife ❶, the
distance from center of needle A to the tip of loop
spreading knife ❶ is 5.5 to 6.5 mm (H type : 5.0 to
6.0 mm).
Be aware that, if the distance between
loop spreading knife ❶ and center of
needle A is reduced, thread loop is likely
to interfere with loop spreading knife ❶.
"7-3-4. Adjustment of the knife unit" p.
* Refer to
72 for how to adjust it.
3) The purpose of adjustment of the aligning position
of loop spreading knife ❶ and thread trimming
knife ❷ (far end of the hole in loop spreading
knife ❶ and the tip of thread trimming knife ❷) is
to align the aforementioned aligning position with
center of needle A.
Be aware that, if the aligning position of
the loop spreading knife and the thread
trimming knife does not align with
center of needle A, the length of thread
remaining on the material after thread
trimming will be longer.
4) The amount of engagement between loop spread-
ing knife ❶ and thread trimming knife ❷ is 2.5 to
3 mm as measured from center of needle A.
Be aware that, if the amount of
engagement between them is
insufficient, faulty thread trimming can
occur.
"7-3-4. Adjustment of the knife unit" p.
* Refer to
72 for how to adjust it.
The needle thread may be trimmed
excessively short in the case thread
such as filament thread which is
likely to cause unstable thread loop
formation is used or thread trimming
is carried out at a position where there
is no material. If the aforementioned
phenomenon occurs, it should be
corrected by carrying out the below-
stated procedure.
• Make the thread take-up spring stroke
larger than the standard value.
• Make the pitch for thread trimming
during condensation stitch larger than
the standard pitch.
• Turn OFF the condensation stitch
operation when carrying out thread
trimming at a position where there is
no material.