JUKI AMS-221F-2516 Instruction Manual page 21

[Regarding H type thread clamp unit]
Change the set value of memory switch U069 in accordance with the thickness of needle thread.
The set value has been set to 1 : H type thin thread at the time of delivery. Commendable value is
Set value : 1 for thread count #50 to #8, Set value : 2 for thread count #20 to #5, and Set value : 3
for thread count #5 to #2. (The value will change in accordance with the kind and thickness of the
actual thread and the kinds of materials to be sewn.) Set the value by adjusting to the state of nee-
dle thread on the wrong side of materials.
In addition, it is possible to select the thread clamp position by means of memory switch U070.
When using thick thread of thread count #5 to #2, and rolling-in or tucking at the start of sewing
occurs, set the set value to 1 : Rear and use the machine. It is recommended to set U070 to "0:
Forward" if wrinkles are formed on the material and/or the material cannot be fed smoothly at the
beginning of sewing when a light-weight material or the like is used.
Use the set value of the memory switch which is adjusted to the thread clamp unit type.
(For S type thread clamp unit, the set value of U069 and U070 can use nothing but only "0".)
When the setting is wrong, the thread clamp fails to properly function. So, be careful.
(1) When with thread clamp (motion), use the sewing machine after adjusting the needle thread length
at the start of sewing to 40 to 50 mm. When the needle thread length is too long, the needle thread
end held with the needle thread clamp may be rolled in the seams.
When needle thread is excessively long at the time of using the thick thread, the end of
needle thread held with the needle thread clamp is rolled in the seams, and slip of posi-
tion of material may occur or needle breakage may be caused.
(2) When the thread clamp is used, and bobbin thread at the sewing start appears on the right side
of material, reduce thread tension at the sewing start (2 to 3 stitches) and bobbin thread becomes
less conspicuous.
[Example of setting]
Tension of 1 to 2 stitches at the sewing start is "20" when sewing tension setting is "35".
* For setting of tension at the start of sewing, refer to
1. Thread at the start of sewing may be rolled in case of some patterns. When thread is
rolled in even after performing adjustment of (1) or (2), use the sewing machine with
thread clamp OFF.
2. Thread clamp failure may occur in the state that thread waste is jammed in the thread
clamp device. Remove the thread waste referring to
device" p.89.
In case of with the needle thread clamp, the stan-
dard of the length of needle thread is 40 to 50 mm.
• To prevent the thread from slipping off from the
needle eyelet at the beginning of sewing or to
prevent stitch skipping from the first stitch
→ Adjust the length of needle thread longer
within the range.
• To prevent stitch skipping within the second to
tenth stitches from the beginning of sewing
→ Adjust the length of needle thread shorter
within the range
"II-2-6-2. Memory switch"
"III-1-7. Needle thread clamp
– 18 –
p.60.