22
(2) Adjusting the timing of hook edge and needle
center crossing
A. First, set the stitch length of (DIAL) KM-750, 750-7,
790, 790-7 types at 2.5mm and KM-750BL, 750Bl-
7, 790BL, 790BL-7 types at 3.5mm. Adjust the
hook gear fastening screw
①
so that like in figure 40,
the hook edge fall exactly at the center of the needle
center when the needle bar is raised 2.4mm from its
lowest position. When this is done, the hook edge
will be placed at about 1~1.5 mm above from the
upper shaft of the needle thread hole.
B. In case of the 790 series, if the height of the left and right needles is not
the same, or if the figure 33 situation-where the needle bar is raised 2.4
mm but the hook edge is not placed about 1~1.5 mm from the upper
shaft of the needle thread hole-is not true, loosen the fixing screw
②
of
figure 34, pull out the needle holder, and adjust the needle holder
position fixing screw
①
up and down to set the height of the needle.
C. Adjusting the distance between the needle and the hook edge
Raise the needle from its lowest point so that the hook center meets the needle center. Like in figure 35, when the
lower shaft of the needle meets the balance point of the hook
’
s needle guide plate
①
(adjust the needle guide form),
adjust the distance between the hook edge and the inner side of the needle groove to 0.05~0.1mm. Loosen
①②③④
of figure 36 and move the left and right
⑤
of the hook base for adjustment.
11) Clearance adjustment between the upper side of hook stopper and the upper side
of needle board groove
Like in figure 37, the normal distance between the hook stopper and the upper side of the needle plate groove is 1.3mm. This
distance is adjusted by the thickness of the space washer
②
that lies under the hook. When the hook gear fixing screw
①
is
removed for repair or replacement, make sure to put back the space washer that was used originally. (as the thickness of the
washer may differ by machine)
[Figure 33]
[Figure 34]
[Figure 36]
[Figure 35]
[Figure 37]
Hook
edge
Lower
Higher
Needle
holder
Hook edge
Needle
Adhering part
