JUKI LBH-772NV-1 Manual De Instrucciones página 71

Troubles
7. The gimp fails to be neatly
enclosed in the stitches.
A. The gimp fails to be
neatly enclosed in the
stitches at the parallel
part of a buttonhole.
B. The gimp slips off the
stitches at the bartacked
part of a buttonhole.
8. Stitch skipping
9. The gimp guide finger fails
to shift the stitch base line.
10. The needle bar comes in
contact with the gimp
guide finger.
11. The pull-in plate breaks.
12. The work clamp check
s l i p s o f f t h e c o r r e c t
position at the start of
sewing.
13. The top end of the cloth
cutting knife is tipped.
(This side of the knife)
Causes
1 The top end of the gimp guide finger is
improperly positioned or positioned too
high.
2 The gimp used is too thick, or the needle
throwing width is to small.
1 Timing to shift the stitch base line for the
gimp between the right and left stitch base
lines is incorrect.
2 Neither the lateral position of the gimp guide
finger nor the leftmost end of the finger are
correct.
1 The needle-to-hook timing is defective.
2 The blade point of the hook has scratches
or burrs.
3 The material flops (particularly when sewing
an overlapped part of the material).
1 The gimp guide shaft actuating rod plate is
positioned too low.
1 The longitudinal position of the gimp guide
finger is improperly adjusted.
1 When the pull-in plate opens, it comes in
contact with the needle.
2 When the pull-in plate closes, the top end
of the plate appears on the slot side to
cause it to come in contact with the needle.
1 The traveling amount of the guide plate
locking pin from its stroke end to the locking
position is too large.
2 The gimp used is too thick, preventing the
pull-in plate from opening with a small
pressure.
1 At the end of a buttonholing, the gimp guide
fingers shifts the stitch base line earlier than
the knife drops.
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™Adjust so that the top end of the gimp guide
finger guides the gimp at the exact center
of the needle throwing width, or lower the
position of the top end of the gimp guide
finger. (Page 25)
™Replace the gimp with a thinner thread, or
increase the needle throwing width.
™Adjust the shifting timing while checking how
the gimp comes off the bartacked portion of
a buttonhole. (Page 30)
™Adjust the position of the gimp guide finger
in accordance with the number of gimps and
the type of gimp to be used. (Page 25)
™Properly adjust the needle-to-hook timing.
(Page 17)
™Buff up the blade point of the hook.
™Decrease the sewing speed.
™Loosen the screw in the gimp guide shaft
actuating rod plate. Then, raise the position
of the gimp guide shaft actuating rod plate.
(Page 23)
™Properly adjust the longitudinal position of
the gimp guide finger. (Page 25)
™Check that the sewing machine stops at the
correct stop-motion position. Then, adjust
so that the locking plate and the guide plate
locking pin are locked when the knife
actuates. (Page 18)
™Adjust the position of the thread trimming
yoke so that the pull-in plate does not
appear on the slot side when the pull-in plate
closes. (Page 19)
™Adjust the mesh between the guide plate
locking pin and the locking plate. (Page 18)
™Replace the gimp with a thinner thread.
™Advance the timing of the knife tripping cam,
or retard the timing of the gimp shift cam
No. 4. (Page 30)
39
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Corrective measures